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Thread: DIY CNC machine on the cheap!

  1. #13
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    Default Re: DIY CNC machine on the cheap!

    Quote Originally Posted by wizard View Post
    I’m not sure what suppliers can do for you in your country, but many around here they can rip sheet goods to size. If you know the width of the boards you need you can have the MDF or plywood pre cut.

    Not having tools can be a huge problem which is where kits come in so handy. The problem with kits. Ring the big jump in parts costs over raw materials and shipping charges. It might not be effective to ship a kit that distance but you might want to look for shops near you with the ability to cut materials to size. Even a wood working shop with a table saw can help with wood or aluminum products.

    It is completely possible to get straight cuts with hand power tools simply by using guides for a saw or router. It is a bit harder to get them parallel. For a guide the edge of factory fresh plywood may do the trick. Parallel cuts require a lot more work on the builders part to align the straight edge.

    I have to agree with others here the gantry will likely be a problem. Gantry are in fact a weak link in many DIY builds. What you want to do here is define the capabilities you need and then design and build to suit.

    Running short on time - hope this helps.
    Hello Wizard,

    Getting factory cut parts around here is a rarity and if you insist, it's waaaayy to expensive. I guess the only people that order them are those really meaning to do business with them. It also doesn't help if you only order a few parts. This is why I'm insisting on a build that can easily be replicated by anyone else interested in building a cheap CNC machine with easy-to-find parts. I know it won't be easy, but I'm aiming to design something which anyone with basic machining skills and a few tools can build. I have visited most of the local hardware stores and to my shock, couldn't find majority of the most common parts most DIY builders use to build their machines!! This has kind of reinforced my insistence on using locally sourced standardized parts. If the prototype turns out great, I believe I'll probably experiment with cutting aluminum (after all, the machine's made of steel), see how well it performs. Should anything break, easy.... just walk up to ANY hardware store and buy what I need. I might have to cut a little and drill a few holes out, but it sure beats the hell out of ordering ridiculously expensive custom parts or ordering a new component off the internet and having to wait! That's my strategy.

    Thanks for your suggestion though, unfortunately, not possible.



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    Default Re: DIY CNC machine on the cheap!

    Quote Originally Posted by routalot View Post
    Well actually I can't see.Its good that you have been visualising the loads on the machine and the additional information suggests to me that a 90mm Z axis travel would do what you need.Which would allow you to reduce the gantry height significantly and by doing so you would reduce the leverage exerted by pushing the tool through the work.The other thing that you might want to consider is that the forces applied to the gantry will tend to twist it and the two lengths of box section in your initial design are sub-optimal.I don't have an easy answer,but you description of how limited the facilities are should be seen as a challenge and not a limitation;a determined man will get the job done.
    You are right about the height of the gantry, I will make it lower. Anything to cut down on costs. I might have to add that to the model later as I have run out of time for now. I have to say, it will definitely be a challenge and I'm looking forward to it. Wouldn't it be nice if all that was needed to build a CNC machine was just a drill press and a table saw (aside from the obvious wrenches, screw drivers and the like)?

    Thank you all and Goodnight! Your ideas were all very helpful!



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    Default Re: DIY CNC machine on the cheap!

    Quote Originally Posted by imbaine13 View Post
    You are right about the height of the gantry, I will make it lower. Anything to cut down on costs. I might have to add that to the model later as I have run out of time for now.
    .
    That gantry is very high.
    I have to say, it will definitely be a challenge and I'm looking forward to it.
    Building things can be a lot of fun. It can be a struggle to balance low cost against the performance you need. Wood products can actually help with cost control.
    Wouldn't it be nice if all that was needed to build a CNC machine was just a drill press and a table saw (aside from the obvious wrenches, screw drivers and the like)?
    I still break down plywood sheets with a handheld circular saw.
    Thank you all and Goodnight! Your ideas were all very helpful!
    Due to the lack of local machinery you might want to build this machine with the intent to make parts for a better machine. There are all sorts of ways to go about this. One consideration is cast aluminum parts. A man named Gingery published a series of books outlining how to build a machine shop out of scrap metal (mostly aluminum) that might be of interest. This might sound extreme but the methods are perfectly valid though not focused on router sized machines. Even if you only use the methods for small parts it might be of benefit for an improved router.



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    Default Re: DIY CNC machine on the cheap!

    Having now seen the gantry in it's revised state it appears to me that you could leave out the wooden brace and drop the rails significantly.Then if you left one of the rails a bit longer you could add a triangulating brace on the outside of the gantry.It would get the forces applied to a shorter lever and retain the stiffness.Looking further ahead,what type of motor will you use and what software to run the machine?



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    Default Re: DIY CNC machine on the cheap!

    Hello guys!

    Just done with another major revision! You think you're done and only after putting the model back together do you realise more areas that might require close attention! Anyway, here are some pictures of Rev 2!

    Attached Thumbnails Attached Thumbnails DIY CNC machine on the cheap!-backside-detail-jpg   DIY CNC machine on the cheap!-cnc-isaac-rev-2-jpg   DIY CNC machine on the cheap!-gantry-close-jpg   DIY CNC machine on the cheap!-top-view-jpg  

    DIY CNC machine on the cheap!-underside-jpg  


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    Default Re: DIY CNC machine on the cheap!

    Quote Originally Posted by wizard View Post
    .
    That gantry is very high.

    Building things can be a lot of fun. It can be a struggle to balance low cost against the performance you need. Wood products can actually help with cost control.

    I still break down plywood sheets with a handheld circular saw.


    Due to the lack of local machinery you might want to build this machine with the intent to make parts for a better machine. There are all sorts of ways to go about this. One consideration is cast aluminum parts. A man named Gingery published a series of books outlining how to build a machine shop out of scrap metal (mostly aluminum) that might be of interest. This might sound extreme but the methods are perfectly valid though not focused on router sized machines. Even if you only use the methods for small parts it might be of benefit for an improved router.
    I agree with you about how much cheaper machines get if wood is involved, but it's a little more challenging for me to use compared to steel box section. Transporting the steel is far easier from the store to my "workshop", i wouldn't have to worry about timber warping or bending when I have to pause working on the machine for significant periods. None of that stress with steel. That's my excuse and I'm sticking to it!

    I did have the intention of using this first build to modify itself if the need arises. I wouldn't mind a steel/wood mix for the structure, but I kind of find it counter-intuitive to use a machine made of steel to make a machine made of wood! I don't see myself cutting any metal with this machine, so I'm assuming that's what you meant. I would only consider building a second machine if the first got too busy. We'll see how things turn out.

    I'd love to take a look at Gingery's book, but only just to see what principles he applies. I don't have to resources to cast any metal parts just yet. Perhaps in the near future, still not sure. Thanks for the reference.



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    Default Re: DIY CNC machine on the cheap!

    So, what modifications did I make?

    1) First and most importantly, I caved and lowered the gantry from the original 450mm. It now stands at 350mm from the same references.
    2) Because of the now limited space underneath the Y-axis rails, I shifted the wooden brace to between the Y-axis rails. This has replaced the vertical supports I had between the rails to keep them parallel under the compression of the bearing running up and down them. The brace also helps prevent flex when cutting along the Y-axis.



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    Default Re: DIY CNC machine on the cheap!

    Quote Originally Posted by routalot View Post
    if you left one of the rails a bit longer you could add a triangulating brace on the outside of the gantry.It would get the forces applied to a shorter lever and retain the stiffness.
    GREAT IDEA!!! Hadn't thought of that! That's actually a lot easier than looking for a 1" thick piece of wood to cut to size and jam in there. The clearances between the bolts holding that brace and those attaching the Y-axis motor are painfully tight! My original intention was to build a machine that didn't require precision drilling, but I was starting to worry that that might get thrown out the window from this point on. Fortunately, with this idea, we can still proceed with my original objectives! I'll try that into the model tomorrow and see how best I can implement it. That would probably be that best this design could get. Thanks again.

    Quote Originally Posted by routalot View Post
    Looking further ahead,what type of motor will you use and what software to run the machine?
    I really hadn't thought that far ahead yet. I was taking it one step at a time, but being a beginner, I'll probably start with freeware just to wrap my head around the mechanics of computer aided manufacturing. It's a steep learning curve, so 'll do my best to worry about one thing at a time. I'd be glad to hear your recommendation. If you're referring to the stepper motors, I'll probably go with NEMA 23. I need relatively high cutting speeds. I'm aware there are many factors that determine this, but I don't want the stepper motors to be the weakest link in that chain! As far as the spindle goes, I have a small Chinese made (brand name: DCA) die grinder in storage that I bought a few years back but have never used. 3mm collet (probably 1/8" for the imperial guys). 16,000 - 30,000 RPM at 220VAC I suppose. I'll start with what I've got on hand and work my way up.

    Boy!...... To think back how confident I was with the first design, if I had only known! Just glad I hadn't even started to build all those weakness into the machine!

    I appreciate everyone's advice! It was very helpful. Still waiting for the parts to arrive. I'll get started as soon as i get the first items!

    Goodnight for today!



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    Default Re: DIY CNC machine on the cheap!

    Quote Originally Posted by routalot View Post
    what type of motor will you use?
    Here it is. It has been gathering dust as you can imagine! Tiny, I know, but I'll upgrade to a bigger one later.

    By the way, I couldn't come up with a way of triangulating the gantry from the outside using one of the Y-axis rails, so I decided I'd continue with the piece of timber between the rails as the final design. I hope it works. I'm glad all those issues were ironed out before I started construction though.

    Thanks for all you input, guys.

    Looking forward to start building.

    Attached Thumbnails Attached Thumbnails DIY CNC machine on the cheap!-20190106_211604-jpg   DIY CNC machine on the cheap!-20190106_211334-jpg   DIY CNC machine on the cheap!-20190106_211419-jpg   DIY CNC machine on the cheap!-20190106_211609-jpg  



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    Default Re: DIY CNC machine on the cheap!

    It looks like you are well on your way to a nice machine.

    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.

    As for wood warping that can be a big issue if you live in an area where the humidity varies drastically. Sheet goods like plywood will minimize the distortion but even sheet goods can be impacted. Honestly I’m a big fan of steel in machine construction so I’m on your side there. Generally though we are talking about steel with larger cross sections. Even with that consideration it looks like your current design is closer to workable.

    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.



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    Default Re: DIY CNC machine on the cheap!

    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.

    Attached Thumbnails Attached Thumbnails DIY CNC machine on the cheap!-tri-gantry-jpg  


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    Default Re: DIY CNC machine on the cheap!

    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.



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