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First CNC help and advice please

Discussion in 'CNC Mills/Routers' started by Beemsquar, Dec 8, 2016.

  1. Beemsquar

    Beemsquar New
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    Hello all ,

    I am looking to purchase my first CNC machine and am looking for some advice.
    I have no experience of CNC machines, but I have used cutters and plotters for my printing business, I am also used to using Illustrator and have been learning sketchup fairly recently, so am semi-comfortable with design software.

    I have been loitering around on this forum and and other sites researching for months, but I feel i need your expert help and advice in choosing the right machine.

    I am a carpenter and am used to using routers and jigs, but want to step my production up a notch.

    I have a few jobs coming up shortly that will require a CNC machine so I am looking for the best options for my situation.
    I will mostly using the machine to make custom made benches and trail signs out of Oak and other hardwoods, logos of companies, maps and plaque recesses will need to be routed into these boards.

    One example I can give you for the size of the materials are the back of the bench is a 1500mm x 500mm x 85mm slab of green Oak, that needs a map routed into the back along with "you are here" markers. I have around 8 of these to make, to start with. I have done this in the past with a handheld router, but it takes too much time.

    The maximum material hard wood thickness I would envisage using would be around 150mm thick and around 2000mm long.

    I will also need to be able to cut full sheets of 2240mm x 1220mm birch ply on the same machine, possibly also brass and maybe alluminium, with the ability to engrave fine detail.

    The main priority is accuracy in the cut, but speed is equally as important.

    I would love to build my own machine, but feel it is a step too far at this point and my time scale, but maybe when I have learnt more I will be able to modify or build one myself.

    I am looking for advice on machines and where to buy, a complete kit supplied with everything including software would be ideal, I am happy to assemble and tune, but don't fancy doing any wiring, but connecting plugs and running cables is fine. I will need it to run from the USB port on my laptop as I have no serial port. I have my own design software, but assume I will need some kind of cutting software.
    I have a budget of around £3500 top end to include everything. Is this doable?

    I have been looking at the Robocutters Rhino CNC with various upgrades, such as the 4Nm nema stepper motors and a Rhino router spindle. can anyone comment on the machine and if it would be suitable for my needs or can you suggest an alternative machine?

    A lot of questions I know, lets hope Ive posted this in the right part of the forum!!

    Thank you in advance!
     
  2. GrayUK

    GrayUK Master
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    I think, considering the sizes you are quoting, as well as the type of materials you intend you use, that you should consider a rack and pinion set-up.
    A belt system, which could meet your size demands would possibly struggle with the oak and similar hardwoods.
    The CBeam could well deal with the demands of the materials, but the size would be a possible problem there.
    However, a Rack and Pinion machine based on Openbuilds Linear Rails and fittings, could give you the size and the strength you would need.
    With large sized CNC's comes the extra consideration of stress and twist it would incur. Strengthening the Axis to deal with the stress means a lot of extra weight, which is why I don't recommend a belt driven system.
    The CBeam will no doubt be able to cope with the material, but CBeam doesn't come in 2000mtr lengths. Plus you will need very long screws, which would need to be at least 15mm diameter to avoid flex.
    Rack comes in many lengths and sizes, and has a different stress area which is spread along the whole Axis,
    Although Openbuilds don't supply R & P materials, have a look at the various R & P systems available, then come back and see how it can be adapted to suit the Openbuild system, giving you the best of both worlds.
    Gray
     
  3. Beemsquar

    Beemsquar New
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    Thanks for getting back to me Gray, I appreciate you giving me your time.
    As far as I'm aware the system in the link above is a rack and ball screw, the pictures are out of date apparently. The website states
    "This model has Twin RACKS on the Y long AXES and 1605 Ballscrew to drive the X and Z axis"

    I dont know if this is better than the belt drive you mention for rigidity, but not quite as good as full rack and pinion and if so could this be upgraded to rack and pinion on the X and Z axis in the future?

    I have found a comparable system that is rack and pinion, but it blows my budget out the water!
    8' x 4' 2015 HD Rack and Pinion Desktop CNC Router Package | www.WorldOfCNC.com

    I could compromise and buy/build a smaller machine if it would be stronger/more accurate, say 1500mm x 1500mm, as I only hope to cut full sheets in the future, (I have work I can quote on for this already though) I just felt it was false economy to buy a smaller machine if I plan on needing a bigger one in the future, although I understand that it would false economy to buy something thats not fit for my purpose!

    A lot of my work at the moment, and the main reason I think I need a CNC machine is custom milled artwork on 2000mm x 150mm x150mm trail posts, is there any reason why for example I couldn't use a smaller machine and just move the workpiece on the bed using a jig and keep resetting the origin to rout each section of art individually? None of the artwork itself is 2000mm long, just the workpiece, but some of the artwork is at the top end of the post and some further down, the maximum artwork length is only 800mm then a gap and then another at 300mm for example.

    I have been reading a bit more and watching some videos on the electrical side of things and I feel that with the right advice on compatible components and some wiring instructions, I could probably go the build it myself route, if it would mean I could get a better machine for the money? time is a factor though as I have a job coming up in the new year. The mechanical side of things i'm fine with, again I would need advise on compatible components, but I feel it is doable.

    I downloaded the bill of material and cost calculator to work this out, but again I can only do this for a smaller machine.

    I have read and will continue to read many build threads on here, but am still a bit lost.

    Again any advice would be welcome!
     
  4. DaleK Morgan

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    By ensuring you get a good amount of vitamins and
     
  5. GrayUK

    GrayUK Master
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    Did you check out these people with regard to R & P? :thumbsup:
    Rack & Pinion
    Likewise for the Electrics have a look at:

    I do seem to promote this company, but their product is good and it is a great explanatory video.
    I know there are other products just as good, but I like this one. :thumbsup:
    Gray
     
  6. Beemsquar

    Beemsquar New
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    Thank you Gray, I did check out CNC4YOU and looked at the rack and pinions, I believe the system I was looking at uses the same R&P system? Unfortunately no complete CNC kits available to buy.

    Thats one of the videos I watched last night, which actually put my mind at rest with the electronics as that all seems pretty straight forward.
    Im starting to get the impression that a full sheet size CNC system might not be possible for my needs and budget?

    Can anyone else offer any advice on this?

    As I said I could use a 1500mm x 1500mm system if there was a way to either raise the Z axis to accommodate materials up to 150mm thick without losing quality of cut or lower the cutting table to allow larger material? I am not proficient enough with CAD software to even start drawing models like this, but has anyone come across this dilemma before and how has it been resolved?

    Again any comment on the system I posted in my first post from Robocutters?
    RoboCutters.co.uk
    The guy seems to think it will do the job well, just thought I would get some advice from people who know more about this than me.
     

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