Dazed and confused on feed/speed suggestions?

[standles]

All:

I have a machine up and running 3HP water cooled spindle

I am trying to get a handle on feed/speeds and avoid learning via broken bits and empty wallet. Rather than ask an open ended question I will limit it to an example.

I have Amana tools
#46316 2 flute spiral upcut carbide 1/4"
#46416 2 flute spiral Dwncut carbide 1/4"
#46322 1 flute Compression carbide 1/4"

In looking at Amana recommendations it comes out to ~175 IPM @ 20K for first two and 130 IPM for compression. These are 1/4" depth of cut pocketing a 1" x 2" pocket in hardwood (poplar)
Using Gwizard it comes in at 70 IPM rough finish and 50 IPM fine finish for first two and 97 IPM / 24 IPM for compression

Much bigger difference than I suspected and gwizard wanted compression faster than 2fl spirals which is opposite Amana.

Looking for guidance or I am just gonna cut a series of test pockets starting at 50 IPM and work up in 20% increments to 150 IPM praying I don't break 30.00 bits

HELP

Thanks, Steven

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[ger21]

Your more likely to break them by going to slow than going too fast.

The 175ipm is probably a decent number, but you can go much faster in poplar. However, faster feedrates can reduce cut quality. I often cut poplar at 300-350ipm @ 18,000 rpm, with about 1/8" depth/pass. I cut shallower to get better cut quality.

Make sure the wood is mounted securely, as a loose workpiece is the quickest way to break a bit.

[standles]

Thx for the reply. Hearing someone experienced say it is not outside realm of believability helps my confidence. I am going to be doing some test cuts this weekend and hopefully not add more entries into the broken bit memorial.

Steven

[standles]

Well I did some test cutting on a pc of 12 x 7 x 3/4 inch poplar. Below is a picture of how it was supposed to look. The numbers under each block are the IPM it was cut at and the legend numbers are the amana tool number.



This was the cut quality before a little cleanup. I was very disappointed



Some time with a razor knife got better but not the quality I was expecting from new cutters.




Any suggestions would be appreciated I know you said you cut at 300IPM but faster would suffer on quality. I might try it again at higher IPM


Steven

[standles]

Went up to 300IPM today with basically the same results.

sigh....

[ger21]

Your results are what I'd expect from an upcut and compression bit. Not the right bits for shallow pockets in hardwood, unless you make a pass with a downcut first.

However, it appears that your downcut is not really a downcut bit, as it should have clean edges, regardless of feedrate. Got a picture of it?

Generally, as feedrates increase, quality will decrease.

On pockets that small, you won't see much difference in feedrate changes, because there's not enough room for the machine to reach full speed. On small operations, I tend to use a low feedrate to minimize machine flex from the direction changes.

[standles]

Gerry:

Here is a quick pic I took headed out the door to work.. Hope it shows what you were looking for. The helix direction between the upcut and downcut look to be opposite to me which is right I am guessing.

[awerby]

Poplar is stringy; those results don't seem too surprising to me. Try maple, cherry or walnut - they cut a lot cleaner.

[bhurts]

If the back wall of those pockets is uneven and humped like it appears to be in the pictures then you have bigger issues then bit choice.

Ben

[standles]

Andrew.. Yeah I am about to come to that conclusion as well. I am about to put Poplar on my hate list

Ben.. The back walls were vertical and not humped. I think it is an artifact of the camera angle I was taking pics at. If you were looking at the cleaned up Pic then that could have been an artifact of me being overly angry with the razor

[ger21]

With the downcut bit, make sure you cut the pocket from the center out, and use conventional cutting, not climb cutting.
A pocket with the downcut bit should be very clean.

[standles]

Thx Gerry

I will give that a try. It was cut raster with a ramp in but was conventional. I will try the offset and trial conventional and climb. I really appreciate all of everyones help in getting me started down right path