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Old 12-04-2019, 11:25 PM
klipsch klipsch is offline
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Default baltic birch feed and speed

Maybe some advice can be shared to help ...

I am still learning with this new to me Stinger III machine with the upgraded 3.0 KW (4.2 HP) spindle.

I will be working with 4'x8' 13 ply 18mm baltic birch for the first time. I was planning to use the amana 46170-K compression 1/4" bit for the work.

After reading other experiences and utilizing some of the chipload calculators, it seemed like a chipload of 0.011, feed rate of 275 IPM, at 12,500 RPM with a depth of .25" per pass might be good starting point?

The amana tool details recommends a chipload of .0031" and rate of 110 IPM at 18,000 RPM:

That is quite a difference from the calculators. I must be doing something wrong.
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Old 12-05-2019, 10:18 AM
Logan Y Logan Y is offline
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The chipload numbers are just a guide to start with. Most people start at half the recommended chip load and work up from there. If it is something you cut a lot of and want to maximize efficiency continually increase your speed until it gets to a point where you either break a bit or the cut quality becomes unacceptable. Then back down your speed a little bit.
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Old 12-05-2019, 11:24 AM
Kyle Stapleton Kyle Stapleton is offline
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We cut at 4ips (240ipm) @ 13000 rpm's
Two passes, pass one is a skin pass down to .05" in climb and pass two is into the table .02" conventional.
Works well for us but not the same cnc (you have more HP).
Kyle Stapleton
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Old 12-05-2019, 12:59 PM
guitarwes guitarwes is offline
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I usually do the same as Kyle with 3/4" Baltic Birth. 1/4" compression bit at 240ipm at 12000-13000rpm. First pass is .71 deep climb cut. Second pass is .758 deep conventional cut. (.75" material thickness is setup in Vcarve if you're doing all profile cuts. Zzero is off the spoilboard. If you keep it at .75" thickness, you have to do a little math if you're cutting exact depth dados or just go ahead and enter .708 material thickness which is 18mm in Vcarve and adjust depths accordingly.)
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Last edited by guitarwes; 12-05-2019 at 01:04 PM.
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Old 12-05-2019, 05:29 PM
Jim Becker Jim Becker is offline
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I do similar on my Stinger II with nominal .75" material...three passes with a .25" compression bit; the first two with a slight allowance and the last at dimension and full depth, not including the tabs I use since I don't have vacuum. (And I don't cut a lot of sheet stock, either) I do allow the speeds to be a bit faster including the RPM and get good results with my 1.7kw spindle. I don't have chatter in plywood, but have to play around with this on MDF if I notice the edges not being as smooth as I prefer off the machine.
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Old 12-05-2019, 08:33 PM
klipsch klipsch is offline
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Thank you all for your suggestions and experiences.

Running at close to full depth and in the 200 IPM range will be a dramatic difference in runtime vs the 110 IPM with .25 depths.

I will find some 3/4 or 18mm plywood "scrap" pieces and experiment with 12k to 13k RPM and ~240IPM at different depths on these pieces and see what happens.

Thank you all again.
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Old 12-06-2019, 06:28 PM
rcrawford rcrawford is offline
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It also depends on the size of the pieces you are cutting and the type of hold down. The reason everyone is suggesting a 0.71" first pass is probably because they have vacuum hold down, and with the full sheet being held by vacuum, you can cut very aggressively and not have the sheet move. As you get less surface area you will need to cut less aggressively.

If you want to cut more aggressively, go up to a 3/8" compression bit. If your vacuum will handle it, you should be able to cut in a single pass at 400ipm and get a nice clean cut. To help with hold down, start your cut in the middle of a long straight area adjacent to the largest remaining bulk of uncut plywood. Ramp your cut. The rest of the sheet will hold your piece in place until the very end, but since the end of the cut is the ramped portion, your pressure will decrease to almost nothing as you reach the end of the cut, so the piece shouldn't move. You just need to be careful if you are cutting smaller pieces - cut them first, and leave your largest piece for last so it has the most surface area for hold down.
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Old Yesterday, 04:13 PM
klipsch klipsch is offline
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I just wanted to thank everyone again for the help and sound advice and share back in case any other newbie searches for this topic in the future.

I ran some tests on 18mm 20" circular ply scrap pieces with the following slot/grooves/profiles/cutouts with a 46170-K by amana.

What seemed to work well was what was recommended here:
12500 RPM
feedrate of 240 ipm

The slot/groove cuts are .25" and were done in one pass at full depths via climb. The cutout and profile cuts were both done the same way with 2 passes: climb with .04 stock left on the axial pass followed by a conventional full depth pass.


This was done with about 4hg vacuum on the stock while cutting.

Thanks again and happy holidays!

edit: specs on 46170-k in inches
compression bit
Shoulder length: .876
Flute length: .875
Diameter: .25
Body length: 1.376
overall length: 2.5
shaft diameter: .25
# of flutes: 2
Attached Images
File Type: jpg testIPM.jpg (10.0 KB, 32 views)
File Type: jpg testIPMtoolpath.jpg (13.0 KB, 32 views)

Last edited by klipsch; Yesterday at 04:16 PM.
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