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| My CNC Router |
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| vtsteam:
That's a great idea, Bill! I bet 90% of what I want to do in future will be small parts. I could make up some bracing clamps that are removable. Also good idea about asymmetry! :beer: :beer: Thanks Country Bubba! :beer: :beer: I have to think about this part. I thought I'd done calculations that showed chip load around .001 but after playing with Little Machine Shop's calculator I see I was still thinking single flute, rather than the change to two flute, and my speed of 8 IPM is wrong by half for 8000 RPM. [ You are not allowed to view attachments ] All I did there was limit artificially the speed of the machine to 8000 RPM. The chipload at 16 IPM will be the recommended .001" then. I'll try doubling the speed. The mfr also gives a max depth of cut in slotting of 1/2D, which is .062" I'm presently at .020" but I'll try .032" next. I wonder about the Little Machine Shop's calculator's results for the very high speeds you found for an 1/8" milling cutter. While it may be theoretically correct for optimal cutting, I wonder if a 1/8" mill shaft would snap under the kind of side force that would generate when slotting. The depth of cut at that speed must be very low. I could probably snap a 1/8" dia carbide milling cutter held in a vise with my hand. Not that I would try! But thanks for that calculator, if the other adjustments go well, I might eventually bump the router speed up a notch and the IPS to suit. GREAT! very appreciative of any and all advice! |
| Country Bubba:
On my cnc mill (RF31 conversion) which is limited to 4000 rpm, IIRC routinely would run ~10IPM with a DOC ~.100" (Trying to boot up my old win7 machine to find my info, but looks like microstooopid had done me in again:{( It won't boot:{( I also ran flood coolant and that makes a difference. OK, took half an hour, but win 7 finally booted and I was able to find my toolset for the 1/8" endmill and I was running at 4000 rpm, feed of 6IPM and as I remember, played around with the DOC (Been a while since I did anything on that machine and even longer on the router for aluminum! |
| vtsteam:
Thanks for that Art. :beer: :beer: That's helpful to compare to. I decided to try another part in the same piece of aluminum, but this time at 16 IPM instead of 8. It cut perfectly fine except for the fact that in redrawing the part I forgot to put in tabs. :wack: Luckily I noticed it at the very last pass, and was able to stop and withdraw the spindle before the part came loose. It's still a usable part, with just a thin skrim of aluminum on part of the bottom. So since that worked out, I added tabs to the drawing, rewrote the g-code, this time with a .032" depth of cut instead of .020". The machine got a few passes down, but got wonky at one point, so I hit e-stop, and withdrew the spindle. I'm not sure exactly what happened. I checked the flutes and didn't see any aluminum welded onto the bit. I checked the router in the mount because I thought I might have seen it rise slightly. Seemed solid. I took it out of the mount and checked shaft play. It clicked when pushed sideways, so I'm thinking maybe the bearings have had it. Could be. It's ten years old at least, and humidity in the shop is high, plus cutting aluminum is going to be hard on router bearings. Not sure what to do now, try to repair, or think about a better spindle. I know I said at the outset I didn't want to buy a new spindle, but now I might have to. I do have one of those little 500 watt 100VDC fan cooled motorized spindles which I use for milling on my lathe. But they seem even lighter weight than the Bosch Colt router. I wonder if they can cut the mustard for milling up to 1/4" in aluminum? They don't look too rugged. [ You are not allowed to view attachments ] |
| vtsteam:
Then there's just replacing the bearings per: https://www.forums.woodnet.net/showthread.php?tid=7355275 Unfortunately he doesn't say what bearings it takes. Wonder if they can be upgraded? |
| RussellT:
Hi Steve I think most Bosch stuff is pretty well made - so I'd be surprised if the bearings could be upgraded. Russell |
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