I was at my local nuts and bolts store yesterday here in Manila. I was looking for thread rod to run a cheap plywood frame 3040 CNC. I had had issues with whipping of the previous machine builds that used m8 rod with a 1.25mm pitch. So I picked up some m12 with a 1.75mm pitch.
they also have up to 30mm thread rod in stock.
I am thinking of going up to 16mm thread rod with a 2mm pitch for a future build.
has anyone messed with the larger thread rod for CNC machines here?
For the Z axis? There should be very little friction, no where near enough to cause and sort of whipping.
For x and y you’ll get whipping even with the bigger threaded rod. None of it is perfectly straight, so you’ll induce some centripetal forces when you spin them. That’s why pretty much all of them will use lead screws, which are ground straight, or belts, chains or a rack and pinion gear assembly.
Bigger rod is higher pitch which is less turns for same movement which equals a lower turn speed of the rod and less whipping along with the added stiffness…
Yes I am very familiar with ball screws and acme screws. I buy them all the time from China.
I build and service CNC routers, 3D printers and co2 lasers full time. This however is my search for a very low cost machine that does not need the China imports.
As far as the z axis goes, I had a m8 thread rod wear out in less than a hour of use with a 1.5kw spindle on a open builds style machine recently.
That reminds me, I need to look at my threaded rod after that last project…
Another thing that occurred to me. With m8 I was essentially limited to 600mm per minute speed.
Going up to m16 should get me 1200 mm per minute with the bigger pitch and added stiffness…
Btw, have you ever seen the lumen labs CNC router? It is machined delrin and acme screws, but it looks printable…
Didn’t Lumen Labs go under 5-6 years ago? I don’t think they ever open sourced their designs…
The ~600mm/m max on Z is due to the 1/32 stepping on the drivers and the Arduino running out of puff generating the signals needed. I’ve set mine to 1/8 stepping and can get ~840mm/m, it’s not 4 times original-speed because of the mechanics, but the CPU seems happier with cycles seemingly spare now and it’s a nice speed upgrade. With larger thread, expect more friction, and I guess don’t expect twice the speed.
I’m planning on running 265 oz steppers for my bigger machines. The entire kit of motors, drivers, power supply and control board is only $150
No lumen labs never open sourced their design. Apparently the creator had health issues.
If I had more budget, I could reverse engineer it and send tp a CNC shop here…
The design was/is quite ingenious.
I posted a set of cad files for a printed variation on thingiverse a year ago.
Thingiverse link to the lumen labs style machine