I’m a beginner in both CNCing and 3D printing, and I’ve built a MPCNC for 75% wood cutting and 25% 3d printing
I’ve bought all parts on the v1engineering shop, and my workspace is about 600x400x145mm.
After a bit of learning, I can now 3d print parts without issues, so I’ve tackled wood cutting, but it’s not going so well. I have an import 500W spindle, and when I cut wood, the spindle seems to “stutter” : it’s cutting a bit of wood, get stuck for a bit, cut a bit of wood, get stuck for a bit, etc. This is not all the time (only on some moves).
It’s working, but it’s making awful noises, and the precision is not good. For example, I’ve cut a 3 cm, 5mm deep square, and you’ll find the video of the cutting and the end result.
(At the beginning, I was a max RPM but smoke appeared so I cranked it down) (And sorry for the video frame, I’m not a good multitasker )
Youtube video : watch?v=jS3Mh70UHFo
(fun starts at around 1 minute)
Some complementary information :
I use a 3mm 4 flutes bit HSS (I didn’t find a better one easily in europe, if someone knows a good supplier I’m interested)
The machine is not on a heavy platform, it’s just on a sheet of wood (for easy transportation)
I didn’t take time to square the machine at is point, I wanted to get good cuts before
If I use higher RPM, smoke happens, and lower RPM doesn’t help.
Finding the correct bits and the correct feed rate is 99% of what CNC machining is all about.
As Barry mentioned, our machines do not move fast enough for 4-fluted bits. You’ll want to try to find a source for either 2 flute or 1 flute bits.
The reason you’re getting smoke is because your cutting surfaces are moving to fast to ‘cut’ the wood and it’s rubbing against the wood… probably producing a really fine dust. That fine dust and the bit rubbing against the wood is causing the bit to heat up.
A bit with less flutes will take less cuts per rotation. So as the machine moves slower, it’s making deeper cuts per rotation (not deeper depth, but deeper sideways… hope that makes sense)… cutting ‘chips’ instead of just scraping and rubbing. The chips coming away from the bit help to pull heat away from the bit.
The other problem with producing dust instead of chips is that it tends to stick in the groove on the material. The heat from the bit starts to heat the dust and it starts to smolder. Great way to start a fire if you’re a pyromaniac…
I wasn’t worried about the smoke since I just needed to lower the RPMs to avoid it.
If the problem is the tooth count, why can’t I solve it by lowering the RPMs to have the same amount of mm/tooth? Is it because the spindle doesn’t have enough torque at this RPM range? (just trying to understand)
You can, but you need to go 4x slower, Most router loose substantial power in the slow range, but then you also have a much smaller flute to evacuate the chips with. high flute count is for small metal chips very slow rpm super rigid machines. Get a single flute, it will be much easier to learn with.
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