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Thread: My CNC Build

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    Default My CNC Build

    Hi all, I was recently motivated by a friend of mine(Vaughan) to build a CNC, I am an IT tech, but have always been in to my woodworking so thought it would be a nice project.

    I am so glad that I found a couple of us SA peeps here. Well thought Ii would share my experiences, up's and down so that the next person can learn from my mistakes and may be help me along the way.

    So where do I start ??

    1. Design:
    Well this was the hard part to make an commitment to the design, I read a lot of forums and spoke to everyone that would listen.
    CNC Cookbook help me a lot
    I finally settled on a moving gantry as I was more in to woodworking then machining. I also tried to skip part of the learning curve by going bigger so that I would not need to purchase upgrade later in live, not sure this was the best idea , but I am committed now
    Part of design questions was size of motors, drive system, and the size of the CNC table. I will supple a list of sources of all the items I eventually bought, with photos of my build to date.

    If you see anything I can improve on please let me know, if you have questions fire away, I am not sure I have any answers for you , but will try.
    Here is my first design, table dimensions are 1600mm x 2200mm. I will post updates and changes I made along the way, but just wanted you to see what I was aiming for.

    My CNC Build-cnc-v1-jpg

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    Default Re: My CNC Build

    Hi where do you stay in South Africa? Interested to build one myself. Stepper motor size? Estimate Cost? Are you using ardiono for driver?



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    Default Re: My CNC Build

    Hi Hennies, I am in East London, probably the worst place in SA from product availability, but the hard part is over. My stepper motor size? I went a bit bigger then most with Nema 34 (12Nm) Hi torque motors, they might be an overkill, but I did not have the appetite to buy small steppers and then upgrade to larger ones later. I do believe Nema 23 would do the job as well. I was advised by my friend to buy it in a kit as it is easier and I would recommend the same. Here is the kit I went with: https://www.aliexpress.com/item/Best-Selling-Wantai-4-Axis-Nema-34-Stepper-Motor-Dual-Shaft-85BYGH450C-012B-1600oz-in-Driver/714368268.html?spm=a2g0s.9042311.0.0.yXFsyB What size table are you planning on ? I would also say if you plan to put reduction gear in play that would affect the size of motor as well, Mine will go straight on to the ball-screw's, if I went with a rack and pinion, and did a 5:1 or 10:1 reduction then Nema 34 would be serious overkill. I am using a USB Breakout Board for the Marc3 or similar G Code processor (USB CNC Controller). You will see that the kit comes with a breakout board, but i do not like the parallel port type. If I had the cash i would go for the Ethernet Smooth Stepper, but that is not an option for now. The cost for my build is a bit high, but then I do have a couple of luxury items in it, I am sure I could cut the cost in some areas by a large margin if I chose to build /weld. How much are you planing / hoping to spend ?



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    Default Re: My CNC Build

    Hi

    How long did it take to order and delivery of the cnc kit. Where did you buy the rack and pinion? How will you reduse backlash on rack and pinion?

    Hennie


    Quote Originally Posted by Earthaddict View Post
    Hi Hennies, I am in East London, probably the worst place in SA from product availability, but the hard part is over. My stepper motor size? I went a bit bigger then most with Nema 34 (12Nm) Hi torque motors, they might be an overkill, but I did not have the appetite to buy small steppers and then upgrade to larger ones later. I do believe Nema 23 would do the job as well. I was advised by my friend to buy it in a kit as it is easier and I would recommend the same. Here is the kit I went with: https://www.aliexpress.com/item/Best-Selling-Wantai-4-Axis-Nema-34-Stepper-Motor-Dual-Shaft-85BYGH450C-012B-1600oz-in-Driver/714368268.html?spm=a2g0s.9042311.0.0.yXFsyB What size table are you planning on ? I would also say if you plan to put reduction gear in play that would affect the size of motor as well, Mine will go straight on to the ball-screw's, if I went with a rack and pinion, and did a 5:1 or 10:1 reduction then Nema 34 would be serious overkill. I am using a USB Breakout Board for the Marc3 or similar G Code processor (USB CNC Controller). You will see that the kit comes with a breakout board, but i do not like the parallel port type. If I had the cash i would go for the Ethernet Smooth Stepper, but that is not an option for now. The cost for my build is a bit high, but then I do have a couple of luxury items in it, I am sure I could cut the cost in some areas by a large margin if I chose to build /weld. How much are you planing / hoping to spend ?




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    Default Re: My CNC Build

    That is a strange size for a wood working router, sheets of ply and MDF are only 1220 wide. The Nema 34 motors are way overkill, you can only run a ball screw up to 1000rpm but with cheap drivers the speed is more like 400rpm before mid band resonance stalls the motors, regardless of how much power they have.The Nema 34 motors would only be of advantage on a rack and pinion or timing belt setup. Also, those motors weigh 5 kilos each and and with that much power you need a ball screw on each side of the "y" axis to control racking. I bought 1600inch ounce Nema34s for my first build, I have them still in my storage box but I will find a project to use them one day.

    A gantry that long would need a massive amount of reinforcing to stop it twisting when cutting in the middle of the table and that 8020 extrusion costs an arm and leg and the shipping will likely cost the other leg.

    Good luck with your project and keep us posted.



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    Default Re: My CNC Build

    Hi, old Capetonian here from way back in '68.........is this your actual build plan?

    It will be a nightmare to build that base to that plan......too many gussets etc.......and BOLTED???

    Do you have access to supplies of square steel tubing.....welding is a much simpler and cheaper way to build......in my opinion........ and you can do a creditable job with a welder after an hour even with a cheap Mig welder.

    BTW, the bigger you make it the harder it is to set up square and align the 3 axes to one another.
    Ian..



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    Default Re: My CNC Build

    I think that Z is going to be far too weak for anything serious. Also the gantry looks too simple and not rigid enough. You need rigidity and stability even if you only plan working with wood. Don't underestimate the forces, it is better to make the machine stronger than needed than larger than needed. Your machine looks far too large and far too weak. Consider major changes and make it stronger before you start building it. NEMA23 motors are all you need, they are strong enough. Avoid USB, go for Ethernet drivers. USB will cause you trouble and Ethernet is not that much more expensive. I am using UCCNC and UC300ETH, but there are other alternatives as well.

    https://adapting-camera.blogspot.com
    https://www.youtube.com/channel/UC_vrAWOz5YGX6_e3qtXg3YA


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    Default Re: My CNC Build

    Hi, a more serious design fault is the spread of the bearing blocks along the Y axis rails.....they need to be at least 3 times the shown length to prevent wracking of the gantry......missed steps.......in one motor...... can happen.

    My preferred CNC router type is a moving table design as the bridge (X axis) and uprights can be made very strong......even if the Y axis is longer.

    To compensate for increased Y axis length, I would make the biggest board dimension the X axis.

    Moving table designs with a single central ball screw do not have wracking problems with the gantry or bridge.
    Ian.



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    Default Re: My CNC Build

    Quote Originally Posted by handlewanker View Post

    Do you have access to supplies of square steel tubing.....welding is a much simpler and cheaper way to build......in my opinion........ and you can do a creditable job with a welder after an hour even with a cheap Mig welder.

    BTW, the bigger you make it the harder it is to set up square and align the 3 axes to one another.
    Ian..
    You are right there, I built a table for my router from welded steel 50X50X3mm. The trick was to bolt on the two "Y" axis support rails at the ends only and then ensure they are level with an epoxy gravity pour and using round supported linear rails also means that any deflection. The table was top was a 36mm sheet of MDF attached to the crossmembers and leveled with the router when it was finished.

    My working area is 620X605 and I am quite surprised that it works as good as it does. Steppers are Nema 23 465inch/ounce, 1605 ballscrews and 16mm linear rails and I use a Makita trimmer for a spindle. I had to get a 6mm and 3mm collet for it from the US but it works well, have had it running for over three hours with no sign of over heating at all.



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    Default Re: My CNC Build

    Quote Originally Posted by handlewanker View Post
    Hi, a more serious design fault is the spread of the bearing blocks along the Y axis rails.....they need to be at least 3 times the shown length to prevent wracking of the gantry......missed steps.......in one motor...... can happen.

    My preferred CNC router type is a moving table design as the bridge (X axis) and uprights can be made very strong......even if the Y axis is longer.

    Ian.
    I did think about building a moving table machine but I just don't have the room in my shed for it. In the OP photo he has two "Y" axis ball screws so racking shouldn't be a problem with the close spacing of the linear bearings but they will have trouble controlling twist from the gantry and the "X" axis carriage is also way to narrow and the linear bearing are too close together, in fact, I doubt there is even enough room for the "Z" axis ballscrew bearing support and ball nut to fit in there.



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