Hello, I've been designing a custom CNC for milling aluminium over the last month. I want it to mill aluminium. I have a 3D printer and so some parts are custom-made, mostly spacers and drill guides. I have some questions, though: 1. Will this machine be rigid enough? Do you have places you can easily see a need to improve? 2. Is there any part of the machine you think could be made more efficiently? 3. Is there a good existing design for a mill that can mill aluminium? I can't go over about $750 in projected costs. Thanks for taking the time to read and answer!
Not with 2040 profiles. Compare it to a known working machine build that use C-Beams (40x80 beams) like the LEAD1010: LEAD CNC 1010 (40" x 40") Also see the Deflection Calculator: https://openbuilds.com/projectresources/how-to-calculate-v-slot®-deflection.175/ Replace the uprights with something more substantial, and fix the Z axis (2040 on Z will probably not work either) Also, moving bed vs moving gantry: Moving Gantry is much simpler and more rigid The Z axis is too high: Longer Z makes for a nice long lever that the cutting forces will use to twist you X rails. This ones going to have a hard time machine acrylic, nevermind Alu. For a little over $750 you can get a MiniMill with motors, and a BlackBox controller. Just add router as seperate buy View attachment 42235 And that can do Aluminum really well (smaller size means more rigidity which you need for Alu)
Hi @ofek256, welcome to the forum - you have come to the right place for advice. I am sorry to say that I think your design is not rigid enough to mill aluminium. Your extrusions are rather light and the vertical members are rather tall and not well supported. Have a look at the C-beam design (C-Beam® Machine - Plate Maker) and you will see it uses more substantial frames and rigid plates to join things together. The US price for the C-beam from Openbuilds is I believe around 590 dollars (plus delivery of course) so it might be worth having a close look at that. Alex
When cutting harder materials it's best to keep a system as lean and tight as possible. Drop your X-axis down at least 80mm. Having it so high up in the air and then having to reach all the way back down to the cutting surface has a serious negative impact on the rigidity of the system and subsequently a negative impact on the ability to cut harder materials. I would also recommend some side plates on the outside faces where the uprights connect to the base frame. Something similar to a T Joining Plate just far more substantial, maybe in the 120x120 mm range. Finally as far as printed parts go, don't go there. If you want to cut metal, use metal.
I've went over my design and decided to try a different setup. All axis are using a C-Beam mechanism. Cut area is about 370x420x105mm assuming 16mm wasteboard. I think the weak point is probably the Z axis mechanism, as it is currently just a flipped C-Beam. Is this any better than my other design? Will it work for aluminium? I think I might give the C-Beam machine a try, but I still want to try to build my own machine. Things like corner brackets have not yet been modeled as of this moment.
Much better! A few things you might look at: Mount the X-axis on the back edge of the uprights. This balances the system better and it also provides more usable area as it pulls the router back into the work surface (ie. hangs off the edge less.) Use larger plates at the X-Z interface. The ones you have will wobble way too much to be useful. Move the router mount down on the router. Gripping it near the base of the spindle is a much more stable connection.
OK - I've added your changes (Massive thanks!) and some of the smaller details into the design. I have high hopes for it! Another question: What motors should I get? Will 3Nm (424Oz-in) for the X and Z axis and 2x 1.3Nm (184Oz-in) for the Y axis work well at decent speeds? Thank you for all your help! ?
424s are too big. Great for snapping bits if that's your goal but not much else. See if you can find some 270s in your part of the world. They are pretty much the sweet spot for this type of system. And use the same size for the both the Y axes that you are using on the X axis. The Y axis is not a 50/50 split on the way the force is distributed. How much force goes to each side is related to where the bit is along the X axis.
I found some 270Ozin motors. I'll use that type on all axis. Regarding stepper drivers, I don't know whether to use TB6600 DM542 or DM556. I heard the chinese TB6600 use a different type of chip which is garbage, so I am not leaning towards them. The DM542 costs the same as a DM556 driver but is rated for less current. I think i'll go for DM556 drivers.
