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Thread: DIY CNC machine on the cheap!

  1. #25
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    Default Re: DIY CNC machine on the cheap!

    Hello guys!

    Hope you've all been good!

    I apologise for the delayed response, work and family got in the way the last few days.

    Quote Originally Posted by wizard View Post
    It looks like you are well on your way to a nice machine.
    Glad to hear that! I'm looking forward to finishing it!

    Quote Originally Posted by wizard View Post
    About that mention of getting materials cut to size, I wasn’t thinking about the factories but rather your local lumber yard. Around here anyways most lumber yards have some sort of panel saw to cut sheet goods. Just a thought.
    We do have those, but it's too much of a hustle getting the parts over there, having them cut up and finally ferrying them back to the workshop! Most of the time, there's long queue!

    Quote Originally Posted by wizard View Post
    As for wood warping that can be a big issue if you live in an area where the humidity varies drastically.
    Incidentally, that's exactly where I live, which is why I decided to totally avoid that path!

    Quote Originally Posted by wizard View Post
    I need to add that die grinders or more specifically Dremel like tools, don’t last long on CNC machines. That brand might be better but I really don’t believe it is that much better. The grinder will get you started but expect a need to upgrade rather soon afterward.
    Understood. I'm really not sure whether or not it's better than a dremel. At the time I bought it, the cheapest I could get a dremel around here was $140 and this only cost me $40!!! I know for sure a dremel is better, but I can't tell by how much. This particular brand does feel sturdy and reasonably well built though. Runs smooth, not too loud. It should work during the CNC familiarisation phase, after which I'll upgrade to a bigger router.

    Isaac



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    Default Re: DIY CNC machine on the cheap!

    Quote Originally Posted by routalot View Post
    This is a very rough outline of the way in which I believe you could triangulate your gantry.The lower end could be held by a through bolt,similar to the other intersections and at the top of the diagonal brace you can saw a couple of straps from a piece of the box section and through bolt them.All you would need to do is extend the upper rail,but of course you could also extend the lower rail too.
    That's exactly how I had done it. Only, I extended the lower rail! Here's where I had problems! I failed to come up with a simple means of connecting this joint, but after considerable thought, I figured whatever method I came up with would beat using the piece of wood, so here's how I did it.

    Attached Thumbnails Attached Thumbnails DIY CNC machine on the cheap!-problem-joint-jpg  


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    Default Re: DIY CNC machine on the cheap!

    Quote Originally Posted by skrubol View Post
    The blue Z rails hang below the rest of the carriage that rides on the gantry. I think this will be the limitation of your part height. I would raise it to be at the same height as the bottom of the carriage. The Z plate will need to be extended downward for your spindle to reach low enough. Alternately, you may be better off with the rails attached to the Z plate and the bearings on the gantry carriage. That seems to be the arrangement most routers with a lot of Z clearance use.
    Hello skrubol,

    I observed that a while ago but it didn't bother me much at the time because I was constantly distracted by other parts of the machine. It wasn't until I measured the clearance after your mention of it (a little less than 50mm (~2")) that I thought something had to be done! I intend to have a 75mm (~3") Z travel, so if I were working on a surface that was say 65mm above the table surface, the Z-rails would definitely hit the work piece if it got in the way. I did some last minute revisions and managed to raise the rails 85mm above the table surface. Thanks.

    Isaac.



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    Default Re: DIY CNC machine on the cheap!

    Alright,

    So here's Rev 3! I was a little concerned about the X-axis rails sagging under the weight of the gantry, so i added some 1mm x 50mm (cross section) metal strips (green) along them. I hope this is good enough to allow extension of the X- axis if the need arises. These metal strips are impossible to bend in that orientation, which should guarantee rigidity along the X-axis rails. They also serve a second purpose of shielding the X-axis against debris from cutting so the linear assembly doesn't jam up. I shifted the wooden table away from the frame in one of the pictures so the attachment is easier seen.

    Attached Thumbnails Attached Thumbnails DIY CNC machine on the cheap!-cross-member-jpg   DIY CNC machine on the cheap!-iso-1-rev-3-jpg   DIY CNC machine on the cheap!-rear-view-cross-member-jpg   DIY CNC machine on the cheap!-x-axis-support-jpg  



  5. #29
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    Default Re: DIY CNC machine on the cheap!

    Quote Originally Posted by imbaine13 View Post
    That's exactly how I had done it. Only, I extended the lower rail! Here's where I had problems! I failed to come up with a simple means of connecting this joint, but after considerable thought, I figured whatever method I came up with would beat using the piece of wood, so here's how I did it.
    Put simply,your proposal will prevent the upper portion of the gantry lozenging.Mine will prevent the whole upper assembly moving.Combining the elements of both could be a good way to go.



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    Default Re: DIY CNC machine on the cheap!

    Quote Originally Posted by routalot View Post
    Put simply,your proposal will prevent the upper portion of the gantry lozenging.Mine will prevent the whole upper assembly moving.Combining the elements of both could be a good way to go.
    I see and understand what you mean, but I think for such a small machine, the 4 upright pieces of steel onto which the Y-axis and whole gantry assembly are attached should be more than enough to resist any tendency to bend sideways. But just in case, I attached a few images of what you mean. After looking through this guy's blog (https://homofaciens.de/technics-machines-cnc-v0-5_en.htm), I'm pretty sure either design would work. This guy has made several CNC machines, starting out with a simple one and evolving his design until he made a relatively decent one out of steel box section! I was impressed when he demonstrated that even machines made of particle board could cut aluminium (not very accurately, but with acceptable results), using the most primitive linear slide designs you could think of!!! And to top it all off, he ONLY uses hand tools (with the inevitability of a drill press). He also does some tests to check how accurate the machines turn out. I think he actually tried making one out of cardboard, but it was probably just a proof of concept for his final design. Watch his videos, you will most definitely enjoy them.

    His experimental machines given me plenty of confidence in my design! I learnt a lot from his experiences and I highly recommend his videos.

    Parts should be arriving soon! Eagerly waiting.

    Isaac.

    Attached Thumbnails Attached Thumbnails DIY CNC machine on the cheap!-alt-gantry-brace-jpg   DIY CNC machine on the cheap!-alt-gantry-brace_2-jpg   DIY CNC machine on the cheap!-alt-gantry-brace_3-jpg  


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    Default Re: DIY CNC machine on the cheap!

    The latest evolution of your machine looks very promising.Thanks for the link to another home builder,it was illuminating to see what he achieved.I would advise caution about going the same way with threaded rod,it will work reasonably well while the wear on the threads is minimal,but is doomed to become less accurate as wear sets in.After all,the threaded rod is usually intended as a fastener and in that situation a nut is only run over the surface once.In the early days of home CNC there were several solutions involving jamming two nuts together to minimise backlash and some used plastic threaded blocks to spread the load.I suggest keeping a stock of threaded rod on hand.



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    Default Re: DIY CNC machine on the cheap!

    Quote Originally Posted by routalot View Post
    The latest evolution of your machine looks very promising.
    I'm glad. I have you guys to thank for that. The guy at the Post Office told me to check this week for the parts I'm expecting. I'm hoping to get most of them before the week ends so I start building during the weekend.

    Quote Originally Posted by routalot View Post
    I would advise caution about going the same way with threaded rod,it will work reasonably well while the wear on the threads is minimal,but is doomed to become less accurate as wear sets in.
    I came across some promising threaded rod early last year at the hardware store whose threads were very deep and well cut. If they still stock it, I'll give it a try although the pitch was low, so the machine will be a bit slow at the start. I was planning to use HDPE for the lead screws but I will upgrade to ACME screws and nuts eventually. I will experiment with the machine as much as I can before I start with the improvements.

    Out of curiosity, have you logged any machine builds on the site? I'd love to take a look. Even if it's just pictures of the finished machines.

    Isaac.



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    Default Re: DIY CNC machine on the cheap!

    I've been following this thread and admire your determination.
    Those green gussets could be used several other places in the design.
    What ties the main frame and cross members together ? It's not obvious in the drawings but maybe you mentioned it elsewhere.

    Anyone who says "It only goes together one way" has no imagination.


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    Default Re: DIY CNC machine on the cheap!

    Hello cyclestart,

    Quote Originally Posted by cyclestart View Post
    I've been following this thread and admire your determination.
    Thanks, easier to correct problems now than much later during construction! I wanted to make sure everything would fit together. With the help of the community, I think I've arrived at the final design for the components I'll use.

    Quote Originally Posted by cyclestart View Post
    Those green gussets could be used several other places in the design.
    This could probably be done as a final step to strengthen areas that would require reinforcement.

    Quote Originally Posted by cyclestart View Post
    What ties the main frame and cross members together ? It's not obvious in the drawings but maybe you mentioned it elsewhere.
    I actually hadn't mentioned it. I will use these corner brackets. Btw, they are also great as guides for a hacksaw blade when cutting the steel by hand. I hadn't included them in the drawing because I was sure they would work.

    Isaac.



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    Default Re: DIY CNC machine on the cheap!

    Doesn't seem like the photo uploaded!
    Here it is.

    Attached Thumbnails Attached Thumbnails DIY CNC machine on the cheap!-20190113_232605-jpg  


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    Default Re: DIY CNC machine on the cheap!

    Quote Originally Posted by imbaine13 View Post
    I'm glad. I have you guys to thank for that. The guy at the Post Office told me to check this week for the parts I'm expecting. I'm hoping to get most of them before the week ends so I start building during the weekend.



    I came across some promising threaded rod early last year at the hardware store whose threads were very deep and well cut. If they still stock it, I'll give it a try although the pitch was low, so the machine will be a bit slow at the start. I was planning to use HDPE for the lead screws but I will upgrade to ACME screws and nuts eventually. I will experiment with the machine as much as I can before I start with the improvements.

    Out of curiosity, have you logged any machine builds on the site? I'd love to take a look. Even if it's just pictures of the finished machines.

    Isaac.
    I have only built one machine from scratch and it is mentioned in this thread https://www.cnczone.com/forums/diy-c...-software.html .It was a learning tool for me as I have programmed and operated four commercial machines,a couple of them 5 axis,and liked the idea of having some of the same capability for my hobby workshop.I didn't intend to build a huge and rugged machine until I was satisfied that i had the ability to make a machine move correctly.Now I have a working tiny machine, I have to admit to a hankering for something a bit bigger.

    If I do build another it will probably have supported round rail and a proper spindle,rather than a router for reasons of noise and power.I would stick with Chinese ballscrews and would prefer my steppers to have a larger shaft than the current version's 1/4 inch although they have ample torque.



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