router table

[planescott]

Hi, I need help on deciding what motors i need for my router table. I have thk rails for all 3 axis , I am going to use rack and pinion setup 12p 12t spur on the x and y I have a ballscrew for the z axis 5 tpi 4" of travel.
My table will cut 24x60" and use up to 3hp router for cutting hardwoods and plywood. My gantry will weigh approx. 50 pounds. I will be using geckos 202s and mach3. I was told that mach3 needs 1600 pulses per inch min. so I am assuming I need a 24:1 gear reduction because the spur gear at 1 revolution is 3" approx. on the rack.
I dont know what I need here. How would I figure out what I need for this setup.
Thank you Scott

[ger21]

I was told that mach3 needs 1600 pulses per inch min. so I am assuming I need a 24:1 gear reduction because the spur gear at 1 revolution is 3" approx. on the rack.

Mach3 doesn't "need" anything. Mach3 can output 45,000 steps per second max. With a G202, you'll need 2000 steps per motor rev. You'll probably want to choose a target speed and gear accordingly without exceding Mach's limit, while still maintaining adequate resolution. Motor torque can also be a factor, especially athigher rpm's.

[planescott]

1/10 micro stepping is 2000 per rev , if i am right i need 3:1 reduction.
am i getting closer?

[planescott]

ok I am assuming that 300rpm on my steppers is a good top speed. If I use a 2.2:1 reduction at 300rpm is 7.13 in per sec , so then that is 14,272 pulses for mach3 a second and well within the range I guess.
Does this make any sense Please help!

[planescott]

ok nevermind the last reply.

I am know figuring 1000 rpm top speed for my steppers x & y axis
I am using a rack and pinion 12t 12p which is 3.14" per revolution. so I
think I need at least a 6:1 gear ratio which would be 523 ipm at 1000rpm
and 8.72" ips mach3 would be putting out 33,333 pulses per sec.
Does this sound like a reasonable setup.
Thanks Scott

[High Seas]

more speed = less power (torque) and its a heavy router I bet - plus the gantry. Sounds like it will be quite a machine though. Looking forward to pictures as it gets built!
Jim

[ViperTX]

I would not use a ballscrew on the z-axis unless you already have a way to keep the ballnut from turning after loss of power....

[planescott]

I guess I will have to play with the gear ratios a little bit. I should have some pictures by next week I will put them on here.

How would I stop the ballscrew from dropping if I lost power?