Expected IPM

[drafterman]

Good morning. I have built my first router table and I am a little unhappy with my rapid speeds (a picture of the unit before the motors were added is attached). It may just be me, but I can only get about 160 to 170 inch per minute rapids. Does this seem normal for 425 oz-in steppers driving 1/2-10 ACME with 1 start? The table has a 4' x 5' bed and everthing is made of 10 ga. steel. I am thinking about stepping up to 2 start thread since I think I have enough motor torque, but I don't know that the motors will handle it since they start to break up around 180 ipm. I would appreciate any thoughts.

Please advise,
drafterman

[Coogrrr]

is that 160ipm combined like 80for x and 80 for y? or is that 160 per axis?

If your using Mach3 and your Feed Rate is 160 then your total combined IPM is more like 320...

What is making you unhappy? is it the speed at which something comes out of the machine (a finished part) or the speed in which the router moves around?

I wonder if you could even put a 1/4 bit through pine at 160IPM and a .25 depth without snapping the bit off?

Just want more info and maybe before you go spend more money or by a double start screw, well maybe we can get you there!

Coog

[drafterman]

Thanks Coog,

I think the main thing is my perception of the G0 movement...it seems slow to me. I guess I seem some higher dollar commercial units and mine seems very slow compared to that. You are right, I will never cut at the combined 320 ipm. My real question is, if I choose to use the 2 start screws, will my motors be able to make use of the higher speed since they are already on the edge at this speed?

Also, I want to thank you for your posts. I have read many of your comments over the past few months and I appreciate everything I have learned from you.

drafterman

[ger21]

You didn't mention what drives you're using and what voltage your running at, which may have a bearing on what you should do.

However, going to a 2 start screw will cut the motor rpm in half at the same speed, which actually may give you more power at the same speed, and should get you moving faster. 160ipm is very, very fast for 1/2-10 acme.

[ger21]

I wonder if you could even put a 1/4 bit through pine at 160IPM and a .25 depth without snapping the bit off?

If you break a 1/4" bit at 160ipm, it's probably from going too slow and overheating the bit with too much rpm, or overloading your spindle.

I recently spoke to someone cutting hardwoods with 1/4" bits at 600ipm. And I know of cabinet shops cutting 3/4" partical board and mdf in one pass, with 1/4" bits, at over 900ipm.

[oeffner]

I don't understand why people are so hung up on rapids. I've worked a 5'x20' $80,000 router and my only concern was the actual accurate cutting speed and tool path. The only time rapids came into play was going to the material location on the table and returning to 0,0,0 when done.
I haven't built a machine yet but the least of my concerns will be the rapid. If the cuts are true to the tool path and done with the desired finish than everything else is gravy

[Coogrrr]

Thanks Ger for the info on those cut speeds you always rock!! I am assuming that the RPM should be set fairly high? The hitachi does 8-24k and if I am going to cut hardwood what rpm for a 1/4" would you think I should use, and does HDPE plastic count as hard or softwood?

Oeffner O agree rapids are not important to me at least not as much as how much IPM in wood/plastic I can do and maintain accuracy.

Am I out of line thinking I can do 200ipm in hardwood with a 1/4" or 1/2" bit and maintain accuracy with that aluminum and stell beast I built?

Coog

Thanks for the brain share guys!

[ger21]

if I am going to cut hardwood what rpm for a 1/4" would you think I should use, and does HDPE plastic count as hard or softwood?

The bit manufacturer should recommend a chip load, which is how much material each flute should remove per revolution. You use the chip load to calculate rpm's for a given feedrate, or feedrate from a given rpm.

Check out this info:
https://www.onsrud.com/xdoc/FeedSpeeds