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OpenBuilds LEAD CNC

Discussion in 'CNC Mills/Routers' started by MaryD, Nov 20, 2018.

  1. Trooper11040

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    If you order from cnc4newbies, make sure you tell them you want the lead pattern to fit the XL gantry plate.
     
  2. wojak

    wojak New
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    I am in Poland, it will be cheaper/easier for me to create it from scratch. All taxes, transport etc may be problematic.
     
  3. Rob Mitchell

    Rob Mitchell Well-Known
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    Any chance you can show a few pictures of the u channel attached to C-beam.
     
  4. wojak

    wojak New
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    sure, ASAP when I will be in the workshop

    But the idea is like in attachment, I've used 8 low profile screws (5mm I think) per profile, squished profiles a little to get nice heavy fit, and them pressed it into c-beam like in pictures in previous posts.

    Profile is 2 mm x 20 mm x 40 mm x 20 mm (20x40x20 cold rolled U profile) and fits perfectly with lead screw nuts and holding screws. Tricky part is to place t-nuts after placing u profile.

    2019-03-18_1125.png

    There are two more tricks I've used in this machine.
    First, I added 0.1 mm precision shims between plates and ACME nut blocks. In CAD and manual measure it was lacking this distance, like nut is 4.1 mm away from plate and we are using 4mm distance (1mm shim + 3mm distance), this 0.1mm seems to play a role at least in noise levels.
    Second, on all plates distances between regular and eccentric wheels are smaller, for example 100mm instead of OpenBuilds 100.6mm, that way I am getting perfect fit with easy movement and I can adjust it a little when needed.
     

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    #364 wojak, Mar 18, 2019
    Last edited: Mar 18, 2019
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  5. gregers05

    gregers05 Well-Known
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    do you have a link to which one? I see the 7" one but it says its for the Xcarve. Is it also compatible with the Lead? Anything else need to be done to do the conversion? I just ordered my Lead and can see myself doing this upgrade after I get the hang of things.
     
  6. Trooper11040

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    It’s the same one as the xcarve but you let them know during the ordering process that you want the lead hole patterns so it can mount to the XL gantry plate. Nothing else needs to be done when you get it. It even comes installed with a limit switch.
     
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  7. gregers05

    gregers05 Well-Known
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    awesome thanks. good to know
     
  8. Trooper11040

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    It’s well worth it...gives you much more clearance than the stock axis. I think the biggest letdown was the z axis on the stock machine
     
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  9. sharmstr

    sharmstr Master
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    Which holes on the Z axis plate does this mount to?
     
  10. Chillimonster

    Chillimonster Well-Known
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    I’ve never been a fan of the moving z axis on the LEAD so I use the z configuration from the Sphinx with a double c beam plate with mind wheels on the inside of the c beam.
     

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  11. Trooper11040

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    The top and bottom of the XL gantry plate. I’ve included photos of the top part to show which ones
     

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  12. sharmstr

    sharmstr Master
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    Thank you!
     
  13. gregers05

    gregers05 Well-Known
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    Well I am still waiting on my Lead order to ship, however I went ahead and bit the bullet and bought this cnc4newbies z axis. The Z axis on the lead is really disappointing. Not even 2" of working height. Thought about it and figured I might as well do this upgrade when I build up the machine from the get go instead of building it and then tearing down the z axis again in a few months. With what I am wanting to do, the 1.88" or whatever it is, is going to make it tough. That height may not even get the bit around work piece clamps.
     
  14. Trooper11040

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    You did make sure to let them know you wanted the lead pattern right?

    Have fun with it! I love my new Z axis!!
     
  15. gregers05

    gregers05 Well-Known
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    Yeah I emailed their customer service and also made the note when I placed the order. It was also on sale for $50 off, so pretty much made the decision easier
     
  16. ljvb

    ljvb Well-Known
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    How much is the upgrade...
     
  17. wojak

    wojak New
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    First alu cut on my Modified Lead CNC. But yeah I have a lot of trouble with Z axis, mostly with spindle mount.

    feed: 1200mm/min
    depth per pass: 0,5mm
    RPM: 20000-24000
    3 flutes VHM bit

     
    #377 wojak, Mar 21, 2019
    Last edited: Mar 21, 2019
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  18. gregers05

    gregers05 Well-Known
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    On sale for $244 with free shipping right now.
     
  19. sharmstr

    sharmstr Master
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    The lock collar and nut block sizes tell you all you need to know :)
     
  20. Batcrave

    Batcrave Journeyman
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    The leadscrew diameter problem has already been covered, but it sounds like you're asking about deflection from spindle weight - and yes, the longer beams will absolutely suffer more from the same load - and even more than you might expect. I'm sure there's a mechanical engineer or two in the thread who can give you the equation, but if I remember right (and I almost certainly don't) the deflection goes up as the cube of the beam length - meaning that adding 1.5x to the beam length will deflect more than 3x as much.

    Theoretically I think this would be an issue with both of the extended versions, as both axes are essentially beams supported only at the ends, but I'd be particularly concerned about the long gantry on the 1500x1500. I haven't seen much discussion of Y beam deflection - presumably because with twice the rails it's twice as well supported so the X is twice as likely to likely to get intolerable before you give half a thought to the Y.

    If you're using a trim router or other light spindle then it might not be a problem - assuming you were able to address the leadscrew whip - but if you're looking at a big beefy water cooled spindle, you'll want to either keep the gantry (at least) as short as you can tolerate, or start taking lessons from Wojak on machine reinforcement (which might not be a bad idea anyhow - while I can't laser-cut my own stainless, I'm definitely considering the pressed in steel profiles).


    -Bats
    ( of course, I could've just looked up the formula in Machinery's Handbook... but then you'd still need the ME to explain what it meant, how to use it, and why it wasn't the right formula in the first place )
     
  21. sn4k3

    sn4k3 New
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    Then that would be a problem. My objective a good working area + able to cut metal, so a bulky spindle with WC is on my list.
    The 1000x1000 version already fit to my purpose, but i asked because the 1500x1500 version is only +50€, was worthy if not drawbacks...
    If i replace the vwhells by linear rails or smooth rods will be more robust or it's more about the frame?

    Is a bundle kit, so i can't remove parts to choose others. But in other way is possible to discard some parts in the box and buy separate parts to reinforce.
     
  22. Batcrave

    Batcrave Journeyman
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    I had a similar thought (although the leadscrew is only half the problem), but unless the vendor's offering it as an upgrade, it's not quite a drop-in replacement.

    Off the top of my head, sized up leadscrews will also need:
    • Larger locking collars. These should be easy to source.
    • Different flexible couplings that fit the motor shaft & leadscrew - these look readily available too (6.35*12mm, right?)
    • Are there some washers or precision shims in there? Those should be easy, too.
    • The C-beam endcaps won't accept the larger screws without drilling the holes out larger. This is low-precision work - a hand drill (or dremel, hand file, chisel, hacksaw, jigsaw, hammer drill, tiny jackhammer) would do.
    • They'll presumably also need new, larger, counterbores to fit the new bearings. This requires some precision, since you need both endcaps and the lead nut all in alignment - probably some careful drill press work, unless you can CNC it (using a center finder for your setup)
    • New bearings - 12mm ID, with an OD to fit that counterbore (except you'll probably want to find your 12mm * x bearings and then size the bore to fit. it's really tricky to change the dimensions of a bearing. err... not that I've tried)
    • New lead nuts. I can't find anyone offering a 12mm version of the Openbuilds design, so the alternative would be making & tapping some delrin nutblocks (Acme taps are obscenely overpriced, so probably making a DIY tap from a spare bit of leadscrew, and/or using the hot leadscrew approach). This should probably also be done in a drill press, since you'll need the hole drilled & tapped perfectly parallel to the mounting side of the block and located to align with the counterbores in the endcaps - otherwise you'll have to shim or trim (make that "shim" - delrin's no fun to trim).
    It's a much less intimidating upgrade than, say, Wojak's BFLead, but there's definitely more to it than "just get larger screws". The alignment's likely to be the biggest headache, though - otherwise you'll be binding whenever you get close to the ends (and potentially damaging the screws/nuts/extrusions in the process).


    -Bats
    ( it's something I would've been willing to tackle when I was just starting out with little more than a hand drill and some screwdrivers... and it's something I would've made a complete and utter mess of )
     
  23. Batcrave

    Batcrave Journeyman
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    Well, if you've got a good (and square) chopsaw, you could add up the cost of the extra length & see if it's worth it just to have some spare bits left around after you cut all the beams back down to 1000mm.

    It depends... I think proper linear rails (round or square) have a lot of advantages over V-wheels, but unless you're going dramatically oversized, I don't think I'd look to them as a solution to rigidity you're giving up elsewhere. If you go for really big rails or really large diameter ground rods it definitely could be more rigid than the base model - but then, bolting some big steel bars and/or rods to the frame would also have a stiffening effect. I think that largely comes down to a question of whether the frame is supporting your rails, or your rails are supporting the frame. This is where the trickier bits of that deflection equation come in - the modulus of elasticity of the two materials and probably the section modulus with has something to do cross sections and numbers and mathy stuff that makes my poor batty brain hurt.

    Unless, of course, you start looking at supported rails. Then you've got all the awesomeness of round rails with the all the rigidity of steel highway bridge I-beams... but it might be cheaper to just buy the bridge (unless you DIY it - I used a hackier version of this on my last machine - but then you're probably looking at a substantial redesign that won't look much like the Lead anymore).

    I've never gotten around to doing an exhaustive search of the forums for reinforcement ideas, but out of the ones I have seen, I think I like Wojak's solution the best for C-beams. That said, I suspect the squishing operation isn't quite as easy as he makes it look, and that it'll also depend on being able to source cold rolled U-profile of the right dimensions (likely easier if you're in a metric country).


    -Bats
    ( "If you're in a metric country" - like, for instance, absolutely everywhere else except here )
     
  24. sn4k3

    sn4k3 New
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    Well that's much to do, but i think i will jump into the adventure...
    I found a shop selling U profiles, but made from aluminium, they must be from steel? Rectangular U
    They don't have the size but maybe they can do it on request.
    Ali sell what we need and with pre holes on all sides or just bottom but require a ton or two to send
     
  25. Batcrave

    Batcrave Journeyman
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    You're trying to stiffen up an aluminum extrusion. Sticking another 1mm layer of extruded aluminum inside it probably won't be quite as effective as you might hope.

    I suspect most places willing to make custom extrusions are, rather like Ali, going to want minimum orders so large that you stop worrying about "I can't afford that" and start thinking "I couldn't store that much if they paid me" - it's not quite like 3D printing (or even milling) where you just plug in the desired dimensions & hit "Go". This mostly goes for metal - you may find exceptions when you get into plastics .

    If you're looking at paying for custom work, though, you might be able to track down some oversized profile (with sufficiently thick walls) and get a local machine shop to mill the sides to fit.

    Or, this video (which I'd forgotten about until I was reading up on reinforcing machines with epoxy granite today... despite the video having absolutely nothing to do with epoxy granite) takes a 40mm square steel tube and slices it in half on a table saw. As is mentioned, that should probably have been reconsidered - although it might not cause a horrendous flesh-tearing disaster to do it the same way (fun fact: "might not cause a horrendous flesh-tearing disaster" is a phrase that comes up with disturbing frequency in my workshop).

    Looking at Wojak's post, I think what he did (and I hope he'll correct me and/or fill in any details I miss, because I'm probably going to have to try it myself at some point) was to get some steel extrusion that was slightly narrower (I don't know how slightly, but probably not much) than the gap inside the C-beam, and then press it until it squishes out to be very slightly larger than the gap, at which point it's then press-fit into the beam.

    The press fit should be easy enough if the U profile is uniform and just the right size... but that "if" is important, and it's entirely dependent on that first squishing operation. That's the part I'm worried might be trickier than it looks. A couple 2x4s and one or more 8" iron C-clamps certainly could do the job as shown (I don't know whether those were a literal part of the process, or just representative of a press), but I suspect it's going to take a lot of care, a lot of cautious twisting, and a whooole lotta really careful measuring to uniformly deform 1.5m of steel like that (three times, too) to fairly close tolerances. I don't know exactly what the margin is between "loose fit" and "hey, my C-beam isn't square anymore!", but it's not particularly large (and it will be the C-beam that deforms, not the steel profile) - and while the eccentrics on the wheels should be able to correct for a certain amount of stretching, that's only if it's perfectly even the whole length.

    Of course, in the interest of expediency (and/or impatience) it might also be possible to bypass all of that by ignoring the close tolerance & press fit stuff completely, getting a profile that fits just-well-enough-not-to-get-in-the-way, and only attaching it with T-nuts. It'll definitely sacrifice some rigidity relative to the pressed-in version, but it should still be a substantial improvement over the unmodified C-beam. Whether it'll be enough... well... discovering that is the exciting part.


    -Bats
    (fun fact: my experience with extrusions goes back many, many years. In the 70s I did a lot of small-batch work for bit of a mom & pop, kitchen table sort of shop, operating a profile extrusion press like this one )
     
  26. ljvb

    ljvb Well-Known
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    Shipping is ridiculous on some of the extruded parts from Ali, some of that has to do with tariffs in the US/China.. but lets not get into the politics of things here. I still have not finished the table for my Lead (my planer/thicknesser belt broke), so mine is sitting unassembled. I'm looking for a larger thickness for my cuts, so I might just get the one linked above.
     
  27. Batcrave

    Batcrave Journeyman
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    Politics aside (not that I disagree), some of it probably also comes from the fact that a lot of those extruded parts are, well, really long. Ten years ago I remember seeing prices of $90 or more just to ship a ~3-4ft long antique... err... thing-that-China-historically-had-lots-of. I don't think I'd even have considered buying 1.5m lengths of anything (at least in "personal use" quantities) as realistic, so the fact that we're even having this discussion could be seen as progress.

    Of course, that still doesn't mean I want to pay the current rates.:p

    Does it make you feel any better if I tell you mine is currently sitting (assembled & running) across a pair of sawhorses?


    -Bats
    (building a table requires more space, which requires reassembling the mill, which requires replacing the spindle bearings, which requires remachining the spindle, which requires outside assistance, which was delayed due to surgery, which worried the cat, which killed the rat, which ate the cheese that lay in the shop that Jack Bats built)
     
  28. ljvb

    ljvb Well-Known
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    Lol, post a picture of the saw horses.. I'm about to just do the same. The table top was built from 42 2x4 cut to 5' Lengths, then milled to 1.5 by 3.5 and face glued to each other. The final thickness of the top was supposed to be 3". I glued them into sections of 8 each, then ran them through my thickness planer to get them to 3", then I would glue the final 8 piece sets to make the top. on the last one, which has the mortises for the legs, the belt melted and it jammed, cause the planer to carve out a giant chunk.. now I am waiting on a new belt, but since a few sets are already glued together I can no longer run them through my planer because they are too large. so I start over.. or just use something else.. saw horses sound good lol.
     
  29. wojak

    wojak New
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    That's exactly what I have done.

    U (or C) profile with 20mmx40mmx20mm dimensions had a nice fit into C-Beam, you can move it with hand, that's why I squished it, thanks to that (I hope) you can have bigger tolerances if U (or C) profile isn't super straight. When pressing Y or X axis when machine is working you can still hear that it is bending, but much less than previously. I showed clamps on picture but you can press it into C-Beam with hand with enough force, it is simply easier to do with clamps. Machine is square, less bending and I can use heavier spindle.

    It was experiment, because I want to make another but much bigger machine, with steel frame that will be connected with U (or C) profiles, so V-slot extrusions will be used only as rail system, not as support.

    About laser cutting plates, it isn't expensive (at least here), or here in Poland even cheaper than buying original plates, only problem is that you have to wait 14-21 days for it.

    Next week I will buy some precise measure tool, and if there will be time I will test bending with and without steel profiles.

    Meanwhile I am testing Igus bearings and rails to create Z axis ;) So in next 2 weeks it should be assembled, then I will attach 1.5k spindle and we will see how steel profiles are performing.

    If you want it to be seriously stiff you may consider supporting C-Beam profile on whole length, instead of having wheels and plates on both sides of profile.
     

    Attached Files:

    #389 wojak, Mar 28, 2019
    Last edited: Mar 28, 2019
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  30. jamin35008

    jamin35008 Well-Known
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    I have the LEAD in my garage and I'm getting ready to assemble. I looked at the 7" z a while ago but didn't get it. Figured I would try out the stock first and see how I like it. Now I'm thinking it might be better to get the newbie 7" now and install while building instead of building and then taking a part again and reinstalling? Thoughts?

    I see that cnc4newbies now has the Lead1010 option for purchace. No need to order the xcarve and request the Lead bolt holes.
     

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