Need Help!- 4th axis build

[contactirfu]

Hi folks - I am planning to add a 4 th axis to my router, for that I want to use the harmonic drive gearbox which I already have, my intention is to hav a shaft coming out of the gearbox and connect it to a timing belt pulley and that will be a direct 1:3 drive from motor to the gearbox,

so eventually I will have a final reduction of 300 times

now the question is how to get a shaft out of the drive, if anyone has used this already pls help me-

I am attaching pics of the drive I have. kindly do help me.

[awerby]

Is there some particular reason you're doing that? My main problem with 4th-axis cutting has generally been insufficient speed, and I'm only using 1/72 reduction. At 1/300, that thing's barely going to crawl, unless you're running it with a super-speedy servo. Is your plan to cut big steel diameters verrrry slooooowly?

Andrew Werby
www.computersculpture.com

[contactirfu]

yup I have a sanyodenki servo motor that can go upto 3k rpm, i have a 250 ppr usdigital encoder which I need to add to it and probably will go 1:1 drive with a gecko 320 which I have already too.- I will be doing mostly wood columns.

RGDS
Irfan

[jeffery71]

Sorry can't help you with the shaft.

I would question the reduction also though. How large of diameter colums are you planning on doing?

Mechanicaly you will get about 10 revolutions per minute from a 3000 rpm servo with a 300 reduction. BUT... If you are using software like Mach. and running at say 45,000... You will only be able to get about 3 revolutions per minute if I have calculated it right. If you can run Mach at the max of 100,000 you will be able to get about 6.66 rpms

Will that be fast enough for you? if they are large diameter colums it may be.

(I don't know of anyone who is running Mach at 100,000 But I'm sure someone is)

Jeff Tice

http://3dcarvestudion.com

[contactirfu]

So I bummed with my calcs - will go with the hundred then 3000/100=30rpm

probably I will just use a stepper with 1:9 reductions.

I have not fixed the diameters for machining but expect all to be within 6 inch dia

RGDS
Irfan