Main > Project Announcements
CNC-2116 - Up and running, sort of (2015-03-21)
Yvan256:
While designing the new CNC machine, I had to find a way to hold those LM8UU linear bearings for the Z-axis. The most compact way to mount them is parallel to the sheet material (MDF or otherwise) so I had to create something simple, compact and easy to mill. Easy for my current little CNC anyway. People with 3D printers make clamp-style holders but with flat sheet material you need to think differently.
I made a rectangular hole, 4mm deep, with four holes for cable ties. The bone-shaped rectangle is to make sure the inside corners are actually square without the diameter of the cutting tool.
The more I move the small plate by hand, the more I think those linear bearings are worthless. Instead of a smooth glide I feel some resistance. The skate bearings assembly feels a hundred times better by comparison. The size and weight difference between the two assemblies, however, is far from negligible. Using the LM8UU will allow me to build a very compact and lightweight Z-axis.
And since I'm starting with the Z-axis assembly anyway, I'll be able to decide if it's good enough once I have it working with a stepper motor and the RTX. Maybe with the stepper motor and the screw moving the plate it won't make much of a difference compared to the skate bearings. So many people use the LM8UU linear bearings with their 3D printers that they can't be that bad.
Yvan256:
Since I can only cut panels 140x90mm with the MDX-3 (150x100mm minus the diameter of the tool all around the perimeter), the design of the bigger machine has to be made from a lot of small panels.
This is what I've come up with for the sides, to fit within the 140x90mm limits and to still get something bigger and yet sturdy enough for the bigger CNC. Twelve panels, 20 bolts, 20 nuts and 40 washers are required for each side. The material used will be 3/8" MDF since the MDX-3 seems to have no trouble cutting it, albeit slowly.
Am I the only one who thinks it kind of looks like a building with windows, from the game Rampage?
nemesismachine:
If the cable ties ever start to loosen or eat into the MDF, you could always go with pillow block bearings. You can order them online, or a lot of tractor supply stores carry them. I used a few for a wheel polisher I made.
TopJimmyCooks:
Wow - you're going to cut 10 pieces of MDF and ~20 bolts. I can't help but think that four full sized pieces would give better, cheaper, more rigid results. Do you have a friend with a tablesaw?
It does look like a good solution to cutting pieces only with the smaller CNC. I don't want to be super negative, but if you're working MDF, you have to have a way to cut larger pieces. It comes 48 or 49" x 96 or 97".
CoryBee:
Love this build!
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