Compression bit selection

[woodshop]

We cut 3/4" plywood with 1/2" straight fluted bits from Lowes ($17 each).
We ramp with 5 passes at 60 ipm and 16k rpm.
Great results!
We are not creating edges which require superior finished cuts. More like rough cutting.

[Kyle Stapleton]

Not to get off topic but what cnc are you running because you numbers sound way off.
We run cheap cmt 1/4" downcuts (kids brake them to often to buy anything better) @ 4 ips with 2 passes 12000 rpms, and get nice edges.
So 1/2" straight fluted bits for 5 passes at 60 ipm and 16k rpm seems really odd.

[woodshop]

ipm (inches per minute)

Pretty darn fast (IMHO).
Shopbot Desktop with router.

We go through 10 sheets of 3/4" ply every month.

[Kyle Stapleton]

Desktop... that is still a little off.
Try a down cut 1/4" 2ips (180 ipm) @ 12000 rmps 3 or 4 passes. (This is what we use on our desktop)

[woodshop]

180 ipm is too fast for our comfort level.
Don't want to tear up a $6k machine.
Anything we cut in our shop ranges between 60-75 ipm's.
We bid our jobs at 60 ipm's.

[EricSchimel]

I agree with Kyle, that's far too slow. You're leaving time on the table. 2-2.5ips is fine for a Desktop. You won't tear up that machine at all. If you cut too fast (which 2ips isn't even close to too fast) at worst you'll just stall the steppers. No damage will happen to the machine.

[robtown]

I agree with Kyle, that's far too slow. You're leaving time on the table. 2-2.5ips is fine for a Desktop. You won't tear up that machine at all. If you cut too fast (which 2ips isn't even close to too fast) at worst you'll just stall the steppers. No damage will happen to the machine.

60ipm = 1 inch per second x 5 passes
That's a glacial pace.
You should easily be able to cut at 160-180ipm at 3-4 passes with those big box straight flute cutters. I do it on my older PRT with a PC router with no issues.
I'd at least consider going to 100-120ipm (approx 1.7-2 inches per second) and cut it 4 passes.
You will not tear up your machine, and you'll double your output (or better)

[woodshop]

We get paid well at 60 ipm. (We see no economic benefit to going any faster than that.)

We are cutting hard wood layered together with exterior grade glues using a half-inch cutter. (Hard wood, hard glue, big swath.)

We hate those hidden surprises in today's sheet goods... knots!

We don't need unsafe speeds in our shop or with our expensive equipment.

In all honesty, we have learned that we don't need those higher feed rates to make money and being SAFE is extremely ECONOMICAL.

[EricSchimel]

You can go faster safely, and if you do your bits will likely last longer so there's your economic benefit! . I often bid my production jobs at lower speeds and then as I get more experienced with the job/material I'm able to push feeds and speeds. That allows for a cushion of down time, and also has allowed me to re-invest in my shop and equipment.

[woodshop]

ok, we'll give it a shot. Maybe try 100 ipm today. Thanks.