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Newbie - Which CNC router to chose ? - build or buy ?

Discussion in 'CNC Mills/Routers' started by cncmystic, Aug 2, 2018.

  1. cncmystic

    cncmystic Well-Known
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    Hi everyone.
    I am totally new here and this is my first post.
    I am just about to embark into the world of CNC routers.
    I have done a lot of reading, googling, pouring through the posts on OpenBuilds, etc...
    I feel somewhat overwhelmed and not able to easily chose which route I should go down with.
    I do not mind spending money as need (within reason as I am retired) but I want to make sure that I buy the right kit so as to avoid finding out a fem months down the road that I should have bought something else.
    Some of the things that spring to mind that will affect my decision include.
    ==> Should be robust enough to route aluminum (I understand that smaller passes will be needed to achieve this compared to a proper mill and that it will take much longer to mill a piece of aluminum)
    ==> I also plan to do wood, acrylic, etc...
    ==> I am guessing that somewhere around 1 meter by 1 meter , plus or minus, should give me enough work area for what I want to do, and space in my workshop.
    ==> I understand that lead screw systems are better than belts (I am happy to be told that this is not the case)
    As I live in the UK, I am sort of drawn towards the WorkBee 1 meter by 1 meter lead screw driven CNC router from Ooznest, but that is based on googling and researching and very limited knowledge of CNC routers (but learning quickly hopefully).
    I also note that you can order the same kit from Aliexpress for a lot less money
    I am also confused as to wheter I should go for GRBL or Mach3/4
    I am also a bit confused about 2.5D and 3D and whether that is all down to the software or if the hardware chosen affects that ability (It would be nice to have 3D as I plan to do carving.
    I do already have a metal Lathe and CNC mill ( the Warco ones) so I am able to turn and create straight forward milled items if needed for the CNC router.
    I would really appreciate it if those much more experienced people could help to guide me a bit so as to enable me to buy the right CNC router so that I can hopefully avoid all the newbie pitfalls of buying / building the wrong CNC router and then having to revisit the whole thing a short while later
    Thanks a million guys. Your help is really appreciated.
    ps. I love this forum. There is so much good and helpful information here.
     
  2. GrayUK

    GrayUK Openbuilds Team
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    cncmystic.
    Welcome to the Forum.
    You don't know how refreshing it is to find someone who has done loads of Research, and pretty much come to a decision on what to buy and build, even before they sign up. :D
    Because you have done loads of reading, you know what we would ask of you, and you have more or less answered all your own questions. :rolleyes:
    Being based in England, Ooznest is the next place you need to go for the final decisions. The guys there are great at helping people to make that final choice. :)
    Personally I favour the fixed gantry / moving bed machines. Mainly because I feel the gantry is the weak point on a machine, and you can really beef it up when it isn't going anywhere. :thumbsup: However, it demands more base space because of the backwards and forwards movement on the platten.
    GRBL is not my area of expertise, and I normally go for the likes of USBCNC,
    CNC USB controller Mk3/4 (4 axis)
    and Mach3/4. Simply because I have found them to be more rugged, more tolerant and more or less plug and play.
    In simple terms, 2.5D and 3D. :rolleyes:
    Well if you go to 2D to start with, this is when you use a laser, or engraver, etcher, or plasma, to cut just one level.
    2.5D is what you would commonly use to cut House names and signs requiring just a straight forward multi-level cut using the Z axis.
    3D is when you require the cuts to be curved or rounded as the cutter cuts into and out of the material.
    Did that make sense? :rolleyes:
    If you have any more questions, which we may be able to help you with, please don't hesitate to ask. :D
    Gray
     
  3. cncmystic

    cncmystic Well-Known
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    Hi GrayUK
    Many thanks for your prompt and helpful reply.
    Interesting that you mentioned fixed gantry / moving bed machines, as that is my view as well since the gantry can be so much more robust from what I can see and I did look around a bit on that , but could not find any such machines/kits around.
    It also means that you could have a very long platten quite easily. One of the things in the back of my mind on the wish list of things I would like to make is wooden kayak oars which would need a working space length of about 2.5 meters so that it can be made in one piece.
    Yes, it does require more space but I could live with that if it gave me that length of working space
    Is that what you have ? If so what is it and where did you get it ?
    I had a look at the USBCNC you referred and it says that you do not need Mach3. Your comment suggests that you are using Mach3/4 with the USBCNC. Could you expand on that please ? I will have a look at the user manual a bit later as well
    Thank you for the description of 2D/2.5D/3D which does make it clearer.
    What I was also asking is whether the hardware has any bearing on whether you would use 2D, 2.5D or 3D from a technical point of view, or does it not matter and it is just down to the software ?
     
  4. GrayUK

    GrayUK Openbuilds Team
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    Check out:-
    C-Beam Machine XL Mechanical Kit – Hobby CNC Mill
    Fixed gantry, moving bed. :thumbsup:
    We have someone else here who makes oars, I think he was from Canada.
    You have to keep in mind that the longer the bed, the larger, in diameter, the screw will need to be, to eliminate whip. These machines come with 8mm screws, which limits you to about 1000mm, before whip sets in. :(
    I am in between machines at the moment, but I'm designing one with a fixed, double gantry for strength, but only about 1000 x 1000mm.
    I'm sorry I didn't explain the USBCNC and/or Mach3. :banghead:
    Do check out Estlcam. It's free to start, and not very expensive to buy. Just do a search on YouTube, there are loads of videos. Especially Trochoidal milling. :D
    Obviously, if you intend to cut hardwoods or aluminium, then you will be making greater demands on your machine. The ones we have mentioned are very capable of dealing with these type of materials, if done sensibly. Indeed, the Trochoidal milling will enable an easier path for milling than the usual method. :thumbsup: So it is both the machine and the programs used, which will determine the performance you achieve. You haven't mentioned whether you intend to go with a router or a spindle? :rolleyes:
    Hope that has made things a little clearer. :D
     
  5. cncmystic

    cncmystic Well-Known
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    Thank you for that Craig.
    In your opinion, would you say that this is the "sturdiest/most rigid" CNC machine that one can buy/build currently (and with easy access to parts. aka openbuilds store, etc...in the UK
    In other words, the best suited CNC machine for doing aluminum and similar harder materials work ? (quite important for me as a fair amount of my work might be with aluminium, though a lot of the work will also be to cut out routing guides/template out of acrylic for manual free routing with a standard router) Though I understand that it will be much slower than using a commercial mill with sky high prices
    I note that it is labeled as CNC mill as opposed as CNC router, which I assume is intentional to reflect the rigidity of the machine and hence suitability for harder materials.
    I note that that machine says max cutting size 750mm x 330mm. Is that 750mm on the Y axis ? ( that is my impression looking at the picture)
    I might be able to work with that, but perhaps a tad too small for quite a few of the projects I have in mind
    If so, it sounds like increasing the x-axis length should not create any reduced rigidity apart from the whipping issue you mentioned beyond 1000mm x axis travel ?
    You mentioned that you are designing one with a fixed, double gantry for strength, but only about 1000 x 1000mm. Does your decision for the double gantry for strength indicate that the one in the kit is still not quite adequate ?
    Are you keeping your design to 1000mm x 1000mm due to workshop space constraints or because of the lead screw whip issue ? If the latter, would it take much to increase the lead screw to a larger diameter to address that ? My thinking is that if I could push it close to 1500mm z-axis work area then I could do an oar half and half at a time, keeping the center of the oar as a reference point to keep things level when doing the second half, then finish the center bit by hand as that is less critical.
    I did not mention spindle or router as I had not yet done sufficient research on this, but whilst we are on the topic, I would be grateful for your recommendations on this. Whilst researching a bit on this, I noted that some members had to build some electronics to control their router/spindle down to about 3000 rpm for acrylics otherwise they were just melting the material on higher speeds. I note that the obvious Makita/Dewalt routers suggested do not go much below 12000 rpm.
    Is that a fundamental difference between spindles and routers ?
    For the varied work I would like to use the machine for, what would you think would be best ?,Spindle or router ? ,and which model would you think would be most up to the job I am after and "matched up" the rigidity of the CNC mill you referred to above, or perhaps more to the point, to the more robust one you are currently designing as I might like to piggy back on that new more robust design if that would be OK for you ?
    Also on the same vein, what power nema motors would be best to match the new design framework you are working on ?
    Would it be best to use the more powerful ones so that there is plenty of power in reserve in case one wants to mod the setup later and require more power without having to upgrade the motors later ?
    I will lookup USBCNC / Mach3 / Estlcam and Trochoidal milling on youtube, etc.. to understand those a bit more.
    Sorry about all the questions I am sending your way, but I am now inspired by the higher rigidity of the CNC mill you referred to or more to the point, to the more robust one you are currently designing.
    I was originally thinking of just going for a straight kit to make life easier, but to gain the additional rigidity,I am considering going down your new design route if that is acceptable with you.
    Fortunately, I do have a reasonable selection of tools, power tools, a lathe and mill. I am also familiar with arduino and general electronics, so that should all help in building a CNC mill, though a bit of a daunting process as it is totally new to me !
    Many thanks
     
  6. GrayUK

    GrayUK Openbuilds Team
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    Hi cncmystic
    Please remember these are my Personal ideas and experience. Maybe just the ramblings of an old man! :D
    "Sturdiest/most rigid"? No. I could never say that. Why? Because you can simply keep adding more and more rigidity to a machine, probably at some cost, both financially and performance wise. Best of the bunch? Probably. You can only apply logic to reach this conclusion.
    You can see why I favour the fixed gantry, but this is still the place for all the stress to become apparent. :(
    FLEX, is the CNC's greatest enemy!! :banghead::banghead::banghead::banghead::banghead:
    We have discussed length, and the X axis is where you really must consider this weakness. I would not go greater than 1 metre without considerable beefing up. I feel that at 1metre the small modifications I make are adequate to enhance rigidity without involving great expense.
    Again, logic says, that the tip of the cutting bit, being the furthest from the point of support, would cause a pivot point on the X axis, when pressure is applied forwards and backwards. (Noticeable on deeper cuts and aluminium/hardwoods) :rolleyes:
    My modification is to simply, double the height of the gantry supports, and place another, secondary C-Beam X axis about 6" above the normal one. By strapping the Z axis to both "X" cross members, you must eliminate that point of pivot. I would use a Linear Rail for ease of fitting and because the purpose of the secondary axis is to eliminate the pivot and the weight is on the lower rail.
    More to follow
    GRAY
     
  7. GrayUK

    GrayUK Openbuilds Team
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    An Experienced Note. Whilst we all have hopes to carve or cut really big pieces with our new CNC, unless built for just a specific need, we usually only use more than a quarter of the available bed perhaps 5% of the time. Better to accept that we really need such big cutting areas because of the "just in case factor!!!" :D:D
    "I note that that machine says max cutting size 750mm x 330mm. Is that 750mm on the Y axis ?"
    Just to clarify, and so we don't start talking at cross purposes; "X" Axis is across, (X) left to right. "Y" axis is forwards and backwards, and "Z" is up and down.
    So the picture shows the X being the 750mm, and the Y being330mm. It is a way to keep the footprint to a reasonable size, with just a little "just in case factor". I'm sure if you were to ask Ryan to modify it to a 1metre Y axis, he would be happy to. Likewise, he could supply longer Gantry supports and the extra C-Beam if you ask him. You would of course need to discuss the additional costs involved, but I'm sure he could do you a great deal.
    So, it is the "Y" axis you need to increase if any. Remember, ideally the Bed will need to traverse forwards and backwards as much as possible to gain the benefit. Due to the actual cutter being projected forward from the "X" axis, the gantry will need to be placed at an optimum position along the "y" axis, to save waste, and use the optimal amount of the bed. (Does that make sense?)
    Obviously, to completely move a 1 metre bed, below the cutting blade, from one edge to the other, would require a "Y" axis of almost 2 metres.
    It is feasable, there is no extra stress involved in increasing the "Y" axis, but, as mentioned before, propulsion is the problem!
    Screws would be out of the question, financially, for such a small gain. Belts would be feasible and cost effective. using dual belts, one on top of the other, gives a system that is cheap, fast and very accurate over the distance.
    The other choice would be Rack & Pinion. (R&P) Now this is the choice, and in many cases, the necessity, for a machine with big footprints. It is very good, but not cheap!!
    So, all in all, a 1000mm x 1000mm bed is probably the target to aim for, using the step process for longer items. (I believe Estlcam and other programs have a method of utilising this process)
    Gray
     
  8. GrayUK

    GrayUK Openbuilds Team
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    Spindle or Router?
    Now there's a choice, but that's life.
    I favour Water Cooled Spindles, because of Speed control, and much much quieter, (important because I use mine in an adjoining basement)
    Water cooled because I tend to use mine at lower speeds, and air cooled Spindles, and Routers, suffer without the internal fan spinning at a higher speed.
    Water cooled Spindles can perform at low speeds all day long.
    Size? These are generally powerful units, and the need for huge KWs is not really a neccesity. My next spindle will probably be, at most, 1.5Kw, and I know that will be more than adequate for my future needs. Weight is a potential problem if you decide to go huge!!! They are heavy units.
    You will need a VFM unit to control the Spindle. Maybe a Spindle and VFM like this:
    CNC 0.8KW WATER COOLED SPINDLE MOTOR ER11 MACH3 PWM WATER COOLING 220V~250V 283961320749 | eBay
    Would be ideal.
     
  9. cncmystic

    cncmystic Well-Known
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    Hi GrayUk

    Thanks again for all the time you are taking to answer my queries. It is really appreciated.

    As you say these are your personal ideas and experience, but I think we are both on the same page on everything we have discussed so far, so that is very encouraging for me as it reinforces my thoughts on all this and it is great to be able to discuss these sort of things with like minded people.

    I should have said "best of the bunch" of what is out there. Ie What is the best result I can achieve with what is out there including any mods that makes it even better.

    I agree that the gantry is the weakest point where most of the leverage occurs due to the distance from the cutting point to the gantry attachment point causing torsion in the gantry which will be worst when the router is is midway on the Gantry. At least with the fixed gantry, some of the issues of leverage and torsion have already been eliminated.

    I follow what you are saying about the X and Y axis sizes and issues.

    I agree with your definition of what the X, Y and Z axis are. I was bit thrown off as in the Ooznest description of the XL CNC mill, it says ..."cutting area - (X x Y mm) 330 x 750" which I suspect is the wrong way around as the X-axis seems to be the longest one based on the photos and bed dimensions. You have just confirmed that my suspicion was right and that their description is incorrect.

    Have you already had experience with the XL kit ? or is your current CNC something else ?

    Are you basing your new 1000mm x 1000mm CNC on the XL kit ?

    In the 1000mm x 1000mm machine you are designing, Am I right in assuming that this is the bed size you are talking about as opposed to the XL kit which is 1000mm x 500mm and you are leaving the x-axis size as is but doubling the Y axis.

    Am I right in estimating that this would give you a cutting area of (X x Y mm) 750mm x 830mm with the moving Y-table protruding out 170 mm at full travel, front and back.(same as the XL model).

    I can see where you are going with the dual gantry C-beam and cross bracing with a linear rail as that would reduce torsion by a very large factor on the main gantry beam and would be very effective.

    For added strength and reducing stress on the "junctions" of the gantry supports and gantries, would it be an idea to also have some additional linear bracings between gantries at 45 degrees to make that double gantry rock solid (a bit like flat roof steel trusses are made) ?

    With the longer y-axis, would anything need to be beefed up in the moving bed axis rails or table movement mechanism so as to prevent deflection when cutting in the x-axis as a bigger leverage will occur when the table is at mid-point of it's travel than with the standard XL kit. I guess we have two deflections to address, Vertical downward deflection and x-axis deflection. I can't see how we could beef this up easily as the table gantries wrap fully around the table rails, other than using bigger rail cross sections. Maybe I am worrying about something that is not an issue for a 1000mm x 1000mm bed ?

    How strong are these wheels and v-groove mechanisms ? At what point do they become an issue once we have beefed up the Z axis, and anything else that can be beefed up ?

    I am still pondering over how to handle the larger projects like carving 2500 mm oars. Yes, I can see how using the step process would work, but on a fixed gantry system, a long piece of approx 2500 mm would need to be fixed to the moving deck and canter levered out into space, causing uneven loading on the table. I guess this could be offset with canter levering a similar weight on the opposite side, which is a possibility, but somehow does not feel quite right.

    I may try this first to see how well it works in practice, but I suspect that longer term, I might land up with the "beefy" plate cutter we have been discussing and then a second larger custom CNC to handle larger wood projects and as you say possibly with belts to handle the length of travel, etc...

    I can see where you are going with the water cooled spindle. I generally get the impression that people eventually move to a water cooled spindle sooner or later for more serious work, so your comments also confirm that. I had a look at the one you provided a link for and the price is not bad. Do these really give you 0 to 24000 rpm or is there a "sweet spot" range that they realistically work best in. Can those also be controlled from the software (ie on/off and speed). I am probably leaning towards going down that route from the start as it seems a far more superior way to go.

    Another "mod" that I am pondering over is as follows... I sometimes have a need to mill the end of a piece of brass, say 100mm x 25mm x 25mm, for use as the "burning bit" for a branding iron. ie milling a logo in the 25mm x 25mm end of that piece of brass. I have done this crudely in the past on my manual mill, but it is very cumbersome to do this like that manually, but the result is a bit crude. This is what sparked me off initially to look at CNC mills. It is possibly feasible to convert a normal mill into a CNC mill but there are a lot of drawbacks to that as well so I decided not to go down that route.

    The issue will be how to do that as there is not enough z clearance to stand a 100mm piece upright.

    I guess the gantry could be raised to provide the required clearance, but you then introduce more issues with deflection. I was pondering in making a hole in the moving bed just big enough for that sort of size material in a part of the bed where it would not interfere with the travel of the bed and that should enable me to "sink" that piece of brass into the bed, but still clear the underlying table. A small vice could be attached to the moving table over the hole to grip the piece of brass during milling.

    I note that some people have used an aluminum plate for the main bed to provide a more solid bed, then add the MDF board(S) on top of that, which gives you a bit more clearance for working Z travel


    If you had to build that new 1000mm x 1000mm bed CNC mill that you are working on from scratch, I would be interested to hear your thoughts on your make/model choices for the motors, electronics, software, router/spindle, etc...ie everything you would chose to build that new machine. As you clearly are way ahead of the curve compared to where I am on this, your experience and thoughts on this (very valuable to me) plus my google research should hopefully enable me to get the right kit from day one rather than revisiting this later and buying more kit later (better to spend a little more money now than lots more over time because of poor choices now)


    Out of interest, where are you based ? I am near Petersfield in East Hampshire (UK)


    Sorry about the load more questions, but this is now getting very interesting as it looks like we are both heading for a very similar build and have very similar views on this !

    It should be real fun to work on this project in collaboration and sharing our experiences !
     
  10. GrayUK

    GrayUK Openbuilds Team
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    Okay, first time I've tried to upload pictures, so it may work or not. This is just a first sketch of what I plan to build next. It is mainly built with C-Beam for strength, and you'll notice there is an absence of wheels anywhere. I call it the One By One simply because the X and Y are 1000 screws. It doesn't refer to the actual bed. However, if I can get a 1500mm "Y" screw from the likes of this Guy:-
    SFU1605-1500mm Ball screw & BK12/BF12 End Support CNC 190459141437 | eBay
    Then there is a strong chance I may have a 1500mm "Y" axis.

    STAGE 4 OF BUILD 2D (1).jpg STAGE 4 OF BUILD 2D (2).jpg STAGE 4 OF BUILD (3).jpg STAGE 4 OF BUILD (4).jpg STAGE 4 OF BUILD (5).jpg STAGE 4 OF BUILD 2D (6).jpg
     
    Rick 2.0 likes this.
  11. GrayUK

    GrayUK Openbuilds Team
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    By the way, I and I'm sure cncmystic, have no problem should anybody else want to jump in and comment. The more the merrier. :D
    I live in a village called Tolpuddle in Dorset.
    As I said, I am in between machines at the moment, and I am having to make my Workshop in the basement a little more habitable, to reduce damp and corrosion of my tools. :(
    Yes it could well end up with corner bracing as well. All connecting plates will initially be made of Acetal from this place:-
    Acetal Plastic Sales Ltd Then cut in aluminium.
    There will be a self-retracting window blind at each end of the table, to expand and contract as the table moves, and protect the screw from rubbish. :rolleyes:
    There could well be another, lighter cross member, above those showing, to cater for the Vacuum pipe, keeping it poised over the Spindle, and removing any drag from the front of the spindle. :)
    Stepper Motors. There is very little need to go Extreme with your Stepper Motors. The Nema 23s sold By Openbuild are really quite adequate for what you have planned. Each stepper has its Sweet Spot as far as torque goes, and many who buy the heavy duty massive torque motors don't do themselves any favors. They never really reach their sweet spot on the curve and probably run with wasted heat and potential. :banghead:
    I don't think there is a sweet spot on a Water Cooled Spindle in truth, but on a fan cooled spindle, there very likely is. :jawdrop:
    Now the "Hole In the Bed" thing. This is the one thing which is soo much easier with a fixed bed! Usually this is located at the leading edge of the bed, and the Router/Spindle overhang, is allowed to exceed the bed limitations to perform the cuts, Dove tailing and the likes. The moving bed obviously comes with problems, but are not insurmountable.
    A lot of CNC tables are strong, as they have to be, but quite often hollow. I guess you could have a removable panel in your bed, and beneath it a vice like clamp to hold your material. Yes it is quite feasible, providing you build your table with this in mind, but would negate an aluminium bed, but that is no great loss in this day and age of non-warping materials. :)
     
  12. cncmystic

    cncmystic Well-Known
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    Nice sketches ! What did you use to create that ? It is great to be able to rotate that in 3D so that you can inspect it from all angles.
    You did a great job of that !
    Hmm! I like it lots !!! No wheels in sight. Yipee !!
    Again, it seems we are thinking along the same lines in that the wheel system is a weakness from my point of view as per the concerns in my last post to you.
    I like the use of linear bearings in that they can be secured all the way along as needed to a very rigid structure, so you could virtually achieve a zero deflection in all axes at right angle to the direction of travel.
    If I may add a few comments ( that is me being OCD about the rigidity). I would be inclined to make the following mods and would be interested in hearing your thoughts on this.
    ==) underneath the moving table --- a few more braces to support the linear bearings so that they cannot flex in the vertical or horizontal direction (ie at right angles to the direction of travel of the linear bearings. Some of these braces to be parallel to the one you have shown in the middle and some X cross braces at 45 degrees to prevent the Y-rails from deflecting, especially as we near the 1500mm length (I like that x-axis length, very useful !! and with your overall design, I think it can be achieved !) Again, just like those flat roof steel trusses
    ==) On the side of the two vertical gantries --- brace them on the front and back at about 45 degrees to the horizontal Y- axis rails to stiffen up the vertical gantries and prevent any high stress on that gantry to Y-axis junction causing possible deflection ( I guess the higher the better)
    ==) On the back of the double Gantry. brace in a similar way to the underneath of the table with parallel and 45 degree braces.
    ==) The one thing I would like to also brace, but I can't see any obvious way of doing this , is to brace the top of the gantries so that x-axis cutting forces do not try and push out on those gantries and cause some deflection. Perhaps this would need some outriggers on the base that such brace could be attached to at 45 degrees to the gantries. Hmmm needs more thought.
    Is there a reason why you have chosen to only have one motor for the X and for the Y axis rather than two per axis ? I ask as I have read a lot about people having issues with jamming or snagging with only one per axis. Perhaps two motors is unnecessary with your design as you have two sliding bearings per sliding rail a good fair distance apart. I do wonder if that would cause some issues when you are cutting quite heavily in say aluminum very close to one Y-axis rail whilst the table is moving. Would that perhaps cause uneven rotational forces on the table, causing premature wear on the linear bearing / slides ? (Again, I am probably being OCD about this with my engineering head on and no practical experience on this yet, though that flag went off in my head based on comments I have seen whilst researching).

    Whatever we do, I think this will be the most robust and rigid hobbyist CNC mill around !!
    I don't mind forking out a bit more money to get that extra rigidity.

    Would you be cutting and tapping all your C-beams and plates yourself ? or would you get someone to manufacture those for you so as to ensure that they 100% accurate

    You have come up with a great design !
    I love where this is going, and I have virtually all but decided to go that route rather than the OpenBuilds wheel based XL kit.
     
  13. cncmystic

    cncmystic Well-Known
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    Yes, It would be great for people to jump in and comment as the more views and comments we have, the more likely this will succeed !

    Tolpuddle is only about 2.5 hours drive from where I live.

    My workshop is quite small too (an outbuilding) and I already have a mill, lathe, drill press, and quite a few other things in there, so I am scratching my head as to where I would fit this 1500mm monster as I guess I would need about a 3000mm x 1200 area with some space to get around it. Some serious reorganising of my outbuilding is needed. I do have quite a large greenhouse that I use as a "work area" now, so it might have to go there !

    What do you plan to use as a table / bench to sit that on top ?

    I like the self retracting window blind idea to protect the screws.

    I had not heard of Acetal before. Sounds quite useful as a material.

    I take on board what you said about the stepper motors and power. The Nema 23s sold By Openbuild come in three power ratings, 175, 265 and 345 Oz. Are you suggesting the 175 Oz ones or one of the more powerful ones for a build such as ours.

    I will have to think about that hole in the moving bed. I would think that a hole in a aluminum bed ( about 50mm by 50mm ) probably should not degrade the strength of that bed at all.

    May I ask why you think that this would negate an aluminium bed ?

    I will go out and re measure my workshop to see how I can reshuffle things !!
     
  14. cncmystic

    cncmystic Well-Known
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    Hi GrayUk
    I had a good measure up in my workshop and I think with a reshuffle I should be able to fit it in there.
    I would need to reduce my "walkway" width a bit, but it would still give me about 700mm to walk between the lathe mill (these are back to back) and where the CNC mill would go.
    I was trying to estimate the overall space needed.
    Assuming the design in terms of overlap of the moving bed is similar to the overlap of the Openbuild XL kit at 170mm, and that one is using a 500mm lead screw, ours at 1500 ball screw with a moving bed overlap of 170mm at each end would give us a maximum working y-axis length of 1090mm (750mm + 170mm + 170mm ).
    I guess the working x-axis length would be as per the XL kit at around 750mm, so overall max working area of x-y 1090mm x 750mm.
    Without overlap of the bed, it would be x-y 750mm by 750mm.
    I think I have got all that correct ? unless you had different thoughts regarding overlaps, etc...
    So workshop space for the unit including overlap would be minimum 1840 mm (1500mm + 170mm + 170mm) by 1000mm
    Say allowing for some space between the unit lengthwise along the wall of say 100mm and 600mm access space at both end, I reckon I would need a floor area of 2700mm x 1100.
    I guess I would need to have some form of lockable wheels on the table where the CNC mill would go so I can pull it away from the wall to access the side facing the wall for maintenance !
    Now to look for a suitable rigid table for this, minimum 1600mm by 1100mm to allow 50mm all the way round the base.
    Ok, space sorted out but a few things will need to find a new home out of my workshop. Small price to pay for acquiring a very useful CNC mill. Lol !!
     
  15. GrayUK

    GrayUK Openbuilds Team
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    Wow! I can never work all that out! I'll pinch those measurements. I will make my bench out of 4 x 2 timber. Loads to copy from YouTube. Some have great storage under as well. :D
    Will you use an old computer or a laptop? I've got loads of Computers knocking around so I'll probably use one of those. It just needs to be pretty basic.
    The design was made in SketchUp. You will need to learn to use a program like this. A lot of people use Fusion360, it has a steep learning curve but is much more versatile than SketchUp. The idea is that you design your project in one of the above programs, convert it to GCode, and then feed it to your machine. A guy on this site created an add-on program called Sketchucam to do just this. :thumbsup::thumbsup:
    Again loads of videos on YouTube to watch. The two I have mentioned are free, providing it is for one machine, and Hobby use. (Nudge Nudge Wink Wink) :rolleyes:
    I think we have a Section on SketchUp and similar programs.
    Download a copy and design your new bench on it. It will make you pull your hair out, but once you have it, you'll be happy. Plus, I can then dump all the drawings onto you to pay with. :ROFL::ROFL:
    I didn't think aluminium would be any good if you need to have a removable panel. I'd use MDF or similar to start with and move on from there. :)
    I do like the 345ozs but I don't know for sure. I will have to look at the power curve to see if it is within the demand. Probably would be okay, or Openbuilds wouldn't sell them!
    Okay that's it for today. :sleepy::sleepy:
    As a thought, can you put a number in front of your questions, :) or even do them a different colour. That way I won't keep losing them and have to keep looking for them again. As well as not answering them :jawdrop:

    See, you've got loads to do yet!! :D
    Cheers
    Gray
     
  16. cncmystic

    cncmystic Well-Known
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    Hi Gray

    1) I have a spare laptop with Windows 10 on it that I can use for that, The way I see it, I can take it indoors to work on designs, etc... then just take it to the workshop and plug it to do the cutting.

    I need to do a bit of research as to whether to use Linux or Windows. I suspect Linux might be better as it is more reliable for control environments as Windows has a habit of doing it's own thing from time to time and possibly halting the process, which might not be an issue for this type of process as the process would just stop cutting and then resume. I will go with Linux if Windows gives me any issues.

    A raspberry Pi would also be a good "computer" to use for a permanent processor with the CNC. It is small, quite powerful and runs a port of Linux Debian. I use them for my automation controllers running as a server. Only about £35.00 or so

    2) Loads of learning to do now and preparation of the workshop area

    3) As building this new rigid monster will take quite a while, measured in many months I am sure, taking into account all other commitments, learning, sourcing all the parts and then making/remaking any brackets and fittings accurately and I do not currently have access to a CNC, I am still considering purchasing one of their C-beam kits to use to manufacture all the components needed for the new big beast as doing this by hand will take forever and not be so accurate so that will save me a lot of time better spent of the new build. It will also allow me to start straight away with the learning curve of machining with a CNC and getting things made.

    This way, I do not have to rush the new build and can start manufacturing bits and pieces straight away and ensure that the new build is a really robust and rigid CNC for the future.
     
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  17. cncmystic

    cncmystic Well-Known
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    Hi Gray
    I have been a bit quiet, busy googling and getting to try and get to understand all that CNC stuff !!
    Yes, I agree that a water cooled spindle seems to be the way to go ...
    Would that spindle you suggest (0.8 kw) be powerful enough for aluminum work ? or would it be better to go for the 1.5 kw one.
    I like that it has a huge range of RPM, especially low RPM for plastics, etc...
    What would be the most practical method for circulating the water cooling ?
    I have seen some Heath Robinson ideas of a bucket of water and a fish tank water pump, but I guess it does seem simple and effective ?
    Thanks Gray
     
  18. GrayUK

    GrayUK Openbuilds Team
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    Morning cncmystic.
    To be honest, I have never heard anyone say that their Spindle has not been powerful enough for what they use it for. Is it because they always judge it right, or is it because they are so versatile, speed wise, I don't know for sure. I know 2Kw is much too powerful, and would be very heavy to use, for myself, .8Kw may be a little too weak, so I like the look of the 1.5Kw. This is not based on any scientific wisdom, just a gut feeling at the moment. I too, will need to research this, before I go for the buy. Mostly, people go for the fishpond pump and a bucket of water. Others utilise water cooling computer parts like radiators and fans to do the job. I've even seen fridge cooler-units used in the hotter climes. Lots of vids on YouTube I think.
     
  19. cncmystic

    cncmystic Well-Known
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    Thanks Gray.
    1.5kw is also the "gut" feeling I have. I will research further on this.
    I think I will definitely go down this water cooled spindle route as I have read quite a lot of issues with standard routers ion that their run outs are bigger and they are not designed for continuous use as in a CNC environment.
    Thanks for pointing those water cooled spindles out to me. Also, they go down right low in RPM with a very good range of RPM
     
  20. Scotty Orr

    Scotty Orr Master
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    I've been looking at these lately as well. I currently use a Makita RT0701C rated at 1.25 HP. It's a bit noisy, but it works OK and has relatively wide speed range (for a router). That 1.25 hp equates to 932 watts, so I would hate to drop down in power (to 800 watts) just for quieter operation. On the other hand, being able to lower the speed below 10000 rpm would be nice (and doing it through software). The only thing that concerns me about the 1.5kW spindles is the weight. So, I am undecided too. Why no 1kW spindles?
     
  21. cncmystic

    cncmystic Well-Known
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    I was looking at the weight of the Dewalt d26200 that seems to be the norm shipped with kits (or Makita). It weighs1.9 kg.
    An .8 Kw water cooled spindle seems to weigh in at 2.6 Kg (65mm x 210mm) and virtually the same weight for a 1.5kw.
    Once you jump to 2.2kw, the weight almost doubles to 5kg.
    So from a standard d26200 to a 1.5kw water cooled spindle, there is approximately 0.7 kg more weight.
    What is the overall weight of the whole moving Gantry including spindle, Nema motors, hardware, etc .. I am guessing at 25 kgs (stab in the dark as I can't seem to find those figures at the moment).
    so the percentage more weight would be about 2.8% more weight ? Would one even notice that ? I doubt it.
    I suspect the weigh issue is probably not the actual weight itself of the whole gantry (unless we place an elephant on that), but rather the inertial weight (ie acceleration / deceleration). I would think that making sure we use powerful enough stepper motors, we can "swallow" all those differences. I think there are tables for the nema motors that provide all that kind of information, but pragmatically, when you see the low power nema steppers used on most machines, if you just fator in to get a slightly more powerful one, I would think we should not need to worry about any such minimal additional weight.
    For me, I am happy to go for the 1.5kw spindle as there is virtuall no weight difference to teh 0.8kw spindle
    These are my opinions based on my thought process, so please do research this further to make sure you are happy with the thoughts.
    What we must not forget is what power outlet you will be using for your CNC setup.
    4 x Nema motors(about 40w), spindle (1500w), driver electronics + power supply (guess 250w), laptop guess (150W), vacuum cleaner(average 1000W) , water pump for cooler (guess 100w), lights for your CNC surface. All these mount up quickly.
    As a quick count,I make this at around the 3000w mark. A 15 amp socket at 240v will give you 3600w, so it should just about do it , (unless my guesses above have been undercooked) but you will not run much else on that socket (bear in mind that a 32amp ring main in a house is the total for all sockets on that ring main and there are often close to a dozen of these around, so you need to also watch what else you have plugged in and running on those socket !
     
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  22. GrayUK

    GrayUK Openbuilds Team
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    Whilst re-building my cellar workshop, I have factored this into the electrical system. I shall split the demands for power across two sockets, each having, independent supplies / MCBs. :p
    I didn't realise the Spindles were so close in weight? :jawdrop: Just made another right decision then! :D
     
  23. Scotty Orr

    Scotty Orr Master
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    I'm having trouble finding/believing the .8 and 1.5 are similar weights. The .8 is 65mm diameter where the 1.5 is 80mm diameter. The 80mm would also require larger mount (and hold more volume water, no?). Seems it should be significantly more weight.
     
  24. cncmystic

    cncmystic Well-Known
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    ScottyOar
    There seem to be different adverts with different figures.(Maybe different makes and models) This one on ebay shows the 0.8 and the 1.5 as being 65mm diameters and the 1.5 as 8mm longer than the 0.8
    I guess they are using the same armature with a few more coils, so if that is true I can believe they are similar in weight. With the same armature, the cooling path would probably be the same as well
    Having said that, I will want to confirm those details before ordering just in case they have messed up the specs !

    1.5KW WATER COOLED SPINDLE MOTOR 1.5KW VFD INVERTER HIGH SPEED MILLING WELL MADE 283961322354 | eBay
     
  25. cncmystic

    cncmystic Well-Known
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    Out of interest, doing more research, I am still wondering about getting a 2.2kw water cooled spindle rather than the 1.5kw one even though it is probably twice the weight of the smaller ones
    A thing to consider is that at the higher RPMs, yes, you seem to get getting most of the power out of the spindle so a 1.5 kw is probably more than enough, but when machining aluminum, slower RPMs are a lot better but that is where the spindle will have least power/torque. I have read in a few places that at those low speeds, the smaller spindles can easily stall, which is a bit pointless if what you want to do is to machine aluminum.
    Yes,some people seem to be machining aluminum at 8000 RPM or higher, but in their comments, they say that you need to go for a deeper cut to create bigger chips so that you do not melt the aluminum, which is fine, but I am fairly sure that you will then be generating more deflection and hence introduce more inaccuracy in your cuts as a result.
    The post below makes interesting reading ... Also I note that he is using the Hitachi X200 inverter , which I have read in a few places as being much better than the Chinese ones.
    I still think that this 2.2kw water cooled spindle should be fine on a standard gantry of a kit like the WorkBee ( same C-beam profiles as the Sphinx or C-Beam machine) which seems quite beefy compared to other and older hobby CNCs, so the extra 2 or 3 kgs of static weight is probably minimal in impact overall compared to the sideways forces of milling which could be hundreds of pounds (I am guessing at these forces but I have seen comments in that ball park)
    So, my current point of view is that I might very well go for a 2.2 kw water cooled spindle and see how I get on.
    I probably will be buying the WorkBee 1000mm x 1000mm as a generic CNC for average tasks as I will need to make a new set of kitchen cupboard doors and this will be big enough to do that job ( and thus pay for itself) and uses screws throughout rather than belts. Also being a moving gantry, I can use "pinning" to make longer pieces such as kayak oars, etc... and milling ends of branding irons. This WorkBee also seems quite capable of aluminum milling as per the following YouTube video so that will enable me to make the plates, etc... for a second CNC that will be purpose built for milling aluminum and perhaps a little steel from time to time.
    That will take that heavier load off the WorkBee so as to reduce wear and tear on that. The new custom CNC will be made just big enough to make what I need in aluminum but no bigger so as to keep rigidity to a maximum (probably a similar size to the small C-Beam plate maker kit, (but wayyyyy tougher and ridid)
    If I find that the 2.2kw spindle is "too big" for the WorkBee, I will use it on the new custom CNC build as that will definitely be built to handle that or even bigger spindles!
    I hope this helps you guys a little.
    It is good to share our research so that we can all benefit from that !!
    ==================================================================================
    "Chinese" spindle minimum speed
    Hi Hirudin,
    Sorry for the late response.
    I've just received my new 2.2KW water cooled spindle.
    Before purchasing I had exactly the same dilemma, as many times when machining steel, or even aluminum with large diameter HSS tools you need rather low RPM.
    Now I have this spindle, and a Hitachi X200 inverter.
    The very first tests that I did was seeing at what lowest RPM I can run it.
    To my amazement, it was no problem at all running even it as low as 200RPM.
    At first it had very little torque at this speed. After playing with some parameters of the inverter, I managed to throw the full 10Amps while turning 200RPM.
    Of coarse it will start to heat up rather quickly, but this is the advantage of water cooling. If you have sufficient pump and radiator, there is no problem.
    I have about 1 liter water reservoir, and a small radiator with a fan.
    I can run it at 200RPM, 10Amps for more than half an hour. It becomes pretty warm to touch, and the reservoir temperature climbs to about 45 centigrade, but that's the hottest it gets. I can continue to run it, and it won't get any hotter. I think that putting a bigger radiator would reduce the temperature even further.

    I tried to mill steel (low carbon) with 3/8 carbide endmill, 0.1mm DOC at 800RPM. It ate it without any difficulty.
    Aluminum is even better.
     
  26. GrayUK

    GrayUK Openbuilds Team
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  27. GrayUK

    GrayUK Openbuilds Team
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  28. cncmystic

    cncmystic Well-Known
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    I called Ooznet about their WorkBee CNC and they recommended not going above 3Kg for the router spindle, which seems odd to me considering all the other huge milling force, but .. that is what they recommend, so better to stick with that for now.
    I asked them about milling aluminum and they said they use the Dewalt 26200 at it's low speed (I think this is 16000 RPM) using an 1/8" or 1/4" carbide bit with a 0.4mm cutting depth and a cut width of the size of the bit and a cutting speed of 600 mm per minute.
    He said they have also done mild steel at 0.1mm depth at 180mm per minute quite successfully.
    Catch 22 for a water cooled spindle right now in that I would need to fabricate a collar to fit the spindle onto the WorkBee before I can use it on that. (I guess I could do a crude wooden one to get going, but I may just start off with the D26200 and work like that whilst fabricating the new dedicated aluminum milling CNC machine and then chose as powerful a spindle as possible for that then and keep the D26200 permanently on the WorkBee, so as not to have to keep switching them around and having to do all the realignment everytime.
    At the moment I am looking into spare parts for the D26200 and those chinese water cooled spindles, specifically for the wearing parts especially bearings so that I can service these myself as the bearings will wear out, and quicker when milling aluminium.
    I am guessing that getting spare for the Chinese spindles may be very difficult, and if so, it means a new spindle when the bearings wear out.
    I have found a site that sells spares for the Dewalt router and the two bearing are about £4.67 and £7.83, which is not too bad, so we know that router can be maintained by ourselves. Their link is
    Dewalt D26200K Type 1 Router Attach Spare Parts | Miles Tool & Machinery Centre
    I also plan to investigate a separate robust spindle shaft and motor with a selection of reduction gears so that I can keep the motor spinning at optimum speeds and control milling range with the gearing or belt pulleys, a bit like it is done on real mills.
    I will keep you posted as I find out more
     
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  29. cncmystic

    cncmystic Well-Known
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    Gray
    Thanks for that .
    I will have a look at that book
     
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  30. Stephen Cain

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    Hi Guys just wanted to say thanks for a most helpful discussion. Having just retired I am keeping busy by making interface panels for a flight sim cockpit (switches etc) that I am building, I have never touched a CNC machine but like cncmystic I am trying to do my research on the best route to start with and this discussion has been most useful. Sadly my workshop would not fit a workbee so looking at the CBeam as my start up option not sure as to the basic or the XL as all my plates will be no more than 200mm by 200mm.

    Again thanks most informative.
     

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