Hi,
I have a Makita. 6mm collet. So I ordered a 3mm collet, and fitted it. Inserted my nice shiny 3mm bit. Tightened the heck out of the nut. 3 minutes later the bit worked loose!
Bugger. This time I tightened the nut to within an inch of its life, and gave it another go. 45 minutes in, out came the bit. I don’t know what to do now.
Any advice?
Duncan
I’m going to guess metric vs imperial and one isn’t actually 3mm.
Too deep a cut at too high a speed will also cause this. Are you using trochoidal milling or are you just bulldozing your way through the material? How deep is your cut and what is your feed rate?
Bulldozing. 3mm DOC 10mm/sec
I gathered that this was a reasonable config?
Both bit and collet are 3.175mm
I need to cut 18mm ply (6 passes) but experimenting with 9mm ply at the moment. I will need to find a 6mm shank, 18mm (minimum) cut length 3mm bit. If not I’ll change my drawings and go 6mm bit. Probably a good idea anyway. 12hr jobs is quite a lot for a 3mm bit I imagine.
Duncan
Bulldozing is OK at shallower/slower cuts based on my experience with my LR2 but chip clearing is a thing to be concerned about. At a certain point it either breaks the bit or the bit slowly pulls out of the collet because of the additional friction from rubbing instead of cutting, build up, etc.
How well are chips being cleared from the cut?
Hi. Very poorly on the first pass. Each additional pass clears the cut channel more, till on pass #4, the cut is almost perfectly clear.
Switch to an upcut bit?
Duncan
Yeah, I’d use an upcut bit, and add a finish pass with your downcut bit if you have a TFT/Screen with a push button to resume the tool path after a M0 machine pause for the change.
Or, stay on top of the path with a vacuum and remove chips as they get packed into the cut. You’re dragging the bit through a lot of friction, which is causing heat. I bet the bit is likely blackened at the end/tip from this. I had the same issue and broke close to 10 bits over two weeks just experimenting.
Got me some 3.175 upcut bits. First run was great - but my machine is completely erratic. This is driving me NUTS!
First, I can’t trust my Z-stepper motors. My spoilboard levelling was an eye-opener. After checking that both ends of the Y-axis were perfect (ie same height) I ran the levelling cut. By the end of the cut, the far end of the tubes as a full 4mm lower than the near end. I tried it again, same result. So I wedged equal height spacers under both XY plates, and ran it again. Voila! Next run (now I had to remove the twist in the table) I used the adjustment on the Makita router itself to drop the spindle 1mm. I had to do this four times to get the bed flat.
With a flat spoilboard, I decided to cut myself two new Y-plates out of 18mm ply (mine are slightly warped). Everything was set up as perfectly as I could get it. Estlcam instructed that the DOC was to be 3mm. 3mm upcut bit. 10k rpm. Feedrate = 8mm/sec. I don’t have a touch plate, so I used the 3D printer trick of sliding a piece of paper under the spindle till I felt the drag of the bit. I then zero’d all axes, and hit print!
The router immediately began ploughing a 10mm deep cut. WTF? I verified that the gcode stipulated Z-3. Those bloody Z-steppers!
I’ve already placed an order for two 92in/lbs Nema17’s, and two closed loop circuits. https://www.aliexpress.com/item/4000580356407.html?src=google&albch=shopping&acnt=494-037-6276&isdl=y&slnk=&plac=&mtctp=&albbt=Google_7_shopping&aff_platform=google&aff_short_key=UneMJZVf&&albagn=888888&albcp=9437580887&albag=98363632680&trgt=296904914040&crea=en4000580356407&netw=u&device=c&albpg=296904914040&albpd=en4000580356407&gclid=CjwKCAjw4_H6BRALEiwAvgfzq0rfxFayeQ1SOhpQdyme7Tgw0mu9eLyRPfo3EXoVp3VqzFruMpG5jBoCRMMQAvD_BwE&gclsrc=aw.ds
I’m sitting here at the laptop, having given up for the day, and scratching my head. I don’t know where to go from here. The plywood sheets for the plane cost $330 each. I can’t afford to waste that sort of money because my machine has a mind of its own!
Anyone have any idea what i can check?
Regards,
Duncan
Grub screws. My money is on those little things causing the problem.
Just finished my second LowRider and had a problem similar to what you describe (almost exactly in fact) and as I was running the program I got lucky to be right by the Z motor and acme screw that slipped. I was in shock because I torqued all those grubs until the allen key nearly broke…
I agree that you should run down the issue before attempting additional cuts in your prime stock. I’m sure others here will chime in on things to check.
Any chance the program didn’t start with a g92? Or that somehow you are working in inches with the dxf? Or something like that?
Weird first moves especially with plunging seem to often be origin related.
Hi,
I’m continuously amazed by how many mistakes one person can make! Ha ha. Yes, I’ve added G92 to my start script, just in case I forget.
Duncan
Grub screws:
I’ve ordered some new ones (the ones which fasten with bolts, not grub screws) so I hope to address this potential issue. As you say, the grub screws can only be tightened so much and no more. Any yet that sometimes is still not enough…
Duncan
Think how much help you’ll be to the next person. Plus, if it makes you feel any better, most of us know this stuff from going through it all ourselves first anyways 
.
Hi. Good to know.
From your handle (banjopete) do I assume you are a fellow banjo player?
Duncan