Thanks to the help from many in the Advice Forum, my MPCNC is finally 99% done and making chips!
Specs:
Rails are 1" Stainless tubing
Steppers are 84 oz/in NEMA 17
RAMPS 1.4 w/Display and Controller w/DRV8825 drivers
Spindle is 500w Chinese with dedicated power supply and speed control
Other power requirements supplied by a converted 300w ATX
X motion: 550mm
Y motion: 630mm
Z motion: 100mm
The primary difference/innovation road that I went down was to avoid the legs, since I wanted to get as much rigidity as possible. I did this by building, what may be best described as a Foosball Table design, in that the printed corner stacks that hold the rails are mounted directly to the table perimeter without the legs/bases. This design offers a bonus of a chip/dust containment aided by an elevated (1") spoilboard and a dust collection port centered underneath it. I know that I can’t expect that setup to evacuate all the chips but it contains and extracts the fine dust. I then just vacuum out the chips manually as required.
I designed and printed my own drag chain and belt anchors/tensioners using 10mm belts. I designed and printed the enclosure for the electronics, and am planning an arduino-based constant-speed controller for the 500watt Chinese spindle.
Yes, I will post more pictures and if anyone wants STL’s or drawings of what I have done, I’d be happy to share.
I’m interested in your dust collection…I’m just starting my build, and I was thinking about a downdraft sanding box as the basis of my table. My idea was plywood top and bottom with holes drilled in the top, with the vac port in the side. Is that the same as what you built?
My dust collection is in the center of the bottom of my table, the spoilboard is elevated on 1" aluminum risers and there is 2" open on all 4 edges. of course since I am just using a shop vac, it doesn’t pull the chips, but I was primarily interested in containing the fine dust, which it seems to do fairly well. I may, in the future, put a chip collection hood/brush on the router in the future, but for now, I am hesitant to obscure my clear view of what is happening at the cut.
As it happens, I’m building a box-like design similar in spirit to yours, but with 2x4’s as the sides.
For me the purpose is to leave the bottom open so I can swap out different sub-floors depending what I’m doing. Maybe one sub-floor has fixtures for mounting panels upright to mill the ends. Maybe another has a light duty vacuum table to hold paper for drawing. Or who knows. And for a small-ish carve on a large workpiece I could take the machine to the workpiece instead of the other way around.
Wow, @jamiek, Those sound like great options. I will be interested to see what methods you come up with to keep your planar alignment. Maybe you can come up with a system similar to the 3D print bed however I don’t think handwheels and springs will mount your work solid enough, so yeah, I am eager to see your ideas for tramming. Now that I have my spoilboard securely mounted, I will surface the whole work area to ensure accurate depth of cut.
I am finding that any opportunity for movement is an invite for tool chatter. I think I will fab up several shim packs to elevate the workpiece into that Z-axis sweet spot. the further down the tool is extended, the slower the feedrate has to be to avoid the dreaded oscillation that flexes the tubes and plastic parts and gouges uglies into your part, or breaks your bit, or both. Slow feedrates are not always optimum feedrates and can result in turning your router into a wood burning kit like you had when you were a kid.
Nice progress on your build. Looks like you’ve used aluminum angle as a bridge to carry your drag chain. I just used a piece of 1/8" x 1" aluminum flatbar and printed some mounting clips that hold it on just on top of the steppers. It looks like you have designed up similar belt tensioners to the ones that I did. I just couldn’t see the 6mm belts being robust enough to do the job so I opted for 10 mm and just doubled up the idler bearings. Since my steppers came with the 1 m wires, and I didn’t feel like crimping a bunch of tiny pins, I just soldered on extensions and used shrink tubing. Then I drilled holes in my tubing adjacent to where the wires come out of the motors and fed them directly into the tubes. It makes a nice neat wiring job I think.
