I’m testing out my cleat wall generator. These are also some of the first real cuts I’ve done on my LR4.
The quality is not very good. The lines are crude and a little irregular. Here are some pictures:
Here are my settings and cut setup:
I also cut one full length finishing pass with 0.32mm stepover (10% of the tool head.)
Any tips for what to try changing first?
There might be some rocking in my core. I tried tightening the bolts that ‘clamp’ it onto the X-beam, and will do another cut.
No dice. Second cut has the same issues.
Try some different plywood or a new endmill. I used to have the same problems:
When I had this before it were the belts being too loose so it would not change the direction immediately but wobble a little.
Are the issues mostly around holding tabs? Make sure your bit and Z are perpendicular to the bed.
Check the grub screws. Obligatory. If those slip, the pulleys can rock on the motor shafts.
You could try a finishing pass. Leaving 0.1mm and them coming back for a no-load pass should give you very accurate cuts.
Is that the same as tramming the router?
I had checked the grub screws but will do again when I’m back at the machine in a few days. Is there something more to do than just tighten and visually check that one is engaged on the flat side?
I am doing a 0.32mm finishing pass. Is that too large?
That should be ok.
Do you have any of that purple HD foam? If you see the errors in that, then something is misaligned. If not. Then it is load dependent.
Oh, good idea. I’ll run that first before taking things apart to check grub screws.
If your core is rocking that can for sure cause what you are seeing. Make very small adjustments until you get all the rocking out of the core. You want all the bearings touching the pipe.
Noticed you have nice Alu cut struts, did that gum up, or damage the bit? Or are you still seeing these cut quality issues with a fresh new carbide single flute upcut bit running on your Makita at a relatively low RPM? Am still learning, observed folks here seem to do ply finish pass of 5-10% of bit’s cut diameter.
Struts are just painted 1/4” hardboard, and it’s a different bit, but I could try a totally new one.
I was initially at a 6 on the Makita but dialed it way down (I think to 2/3?) and increased feed rate because I could smell the wood burning and see the edges darkening. The second test cut I did was not discolored on the sides, but still misshapen.
If you are still using the same bit that you smelled the burning wood with then that one is toast most likely. Time for a new one.
OK, so things look mostly right in purple foam. Nowhere near the errors I saw in plywood. So I think this has to do with load.
What should I look at here? Just smaller depth of cut? How can I improve the machine’s behavior under load?
I’ll second the bit swap if the mill is cooked because you could smell it. Does it appear discolored on the cutting end? It looks like you are cutting maple ply. That is hard. Id slow to 7 mm/s and run the makita router at 3, but that might still be high. Less aggression may help you if your bit is sharp, but you should be in the ballpark as it is.
7 mm/s? That seems way, way too slow with the router at 3. Doesn’t that mess with the chip load?
Since i dont have the same material you have, it is an estimate. If it is too far off of your intuitive spidy sense it may not be good advice and your experience here should be the better gauge. The router probably needs to be slowed. The intent was to minimize cutting deflection, if that was the issue, by slowing down, however it sounds more like the mill needs to be replaced.
I don’t have evidence to back this up, but I think there is a sweet spot where things work well and you have sharp bits and you’ve got the router speed right. But there is also a very conservative speed where you are making dust and heat, but going slow and deep enough that the bit stays good for longer and you can still get something accurate and good.
We used to make a lot of projects in what I’ll call the “dust zone” around 8mm/s and that works but isn’t optimal. But halfway between the ideal and the dust zone is a zone where you get a lot of heat and destroy bits.
That’s my guess. But I haven’t really done any tests to confirm that.
I decreased my depth of cut and tightened my Y belts a bit. I also switched to drilling the holes with a boring bit before swapping for a endmill to profile. That really seems to have helped!
Still the holes look a little off kilter. Not sure what I’m doing wrong there, but if they were lined up the rectangle holes would be way too big. So… who knows!
Why are you drilling holes instead of doing dog bones in the CAM?
I am doing dog bones in the original sketch. The issue is that they are 1 bit width in diameter, which means that they are mostly cut by the full-depth finishing pass. This was causing deflection.
But, now that I’ve written that, maybe I can just up the diameter to like 1.25 bit width. I’ll try it tomorrow.
