Belt Drive Conversion for Grizzly G0704

I'm curious how this worked out. Are you cutting steel with it using the factory motor? I'm planning to do this conversion as well, but I was worried that at low rpms, the motor may not have enough torque, even considering the vfd.

Thanks!
 
I went ahead and did this mod yesterday, I'd post pictures, but it's pretty much identical to what the OP did. To answer my question, the machine has no problem cutting mild steel down to 600 rpm, the VFD does a great job of maintaining the rpm. As an added bonus, my cuts are looking much cleaner than when it was gear driven. I'd imagine that's because there's no backlash now between the motor and the spindle, where the gears would obviously have a bit of play.

I'd recommend this project!

Thanks for taking the time to post your work, you've saved me a bunch of time.
 
C'mon zaaephod, please post pics, there always something new to see :))

Thanks-
 
Tell ya what, I'll post pics when I'm done with my pneumatic draw bar project, hopefully this weekend.
 
That would be awesome thank you, might as well start your own thread then, but looking forward to both projects!

Thanks again-
Dave
 
As I promised I would post a pic when I did the new motor. I still have allot to do .Sorry for the crappy pic I will try to post a better one if any one wants to see it.
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I'm thinking of doing this to my g0704. My plastic gear just bit the dust.

How do you figure which belt you need? And how long it needs to be.

I see you used the 25 and 36 tooth pulleys so I will go with them.

Ron

With the extreme cold weather, i have not had a chance to use the machine much since the conversion - as for how to figure the belt, I took center to center distance between the pulleys and added half the circumference of each pulley to come up with the belt length. Or, since you can see the part number on the belt I used in one of the photos, if you use the same pulleys, you should be able to use the same belt. I chose the 36 and 25 tooth pulleys to get a slight speed increase without going too far - one article I read about the conversion used two 36 tooth pulleys, I believe, and the author warned that the result was faster than the stock bearings were rated for, so I deliberately kept it on the low side. I'm hoping to spend more time in the shop now that the weather is starting to warm up a little. Glad my tinkering helped some of you out with your machines! Nice to hear positive reports from those of you that had good luck with this method. Interesting to hear the comment about smoother cuts, too.
 
Hello,
New to the site and just in the middle of my own belt drive conversion albeit on an Optimum BF20.

I had been wondering how to fix the Drive pulley onto the spindle carrier and see now how its done on the G0704. The 5mm flange that sticks up has no screw holes in it on the Optimum as the RPM's are measured with a sensor and magnets.

Can I ask you the diameter of the screw you used and the thickness of the 5mm flange? In other words how much meat was left on the flange around the threaded holes. I am a little worried about making the hole too large and the walls too thin, but at the same time want enough thread bite to hold the pulley.

Thanks!
Phil.
 
If I examined your previous photos and description correctly, you opted to not reinstall a key on the motor shaft and instead just used a set screw? Please correct me if I am mistaken on my observation, but this will only serve to destroy your keyway as the screw digs into the sidewall due to the cutting forces on the spindle. It didn't look like Grizzly gave you a very pretty motor shaft keyway from the start either, so it may not be any worse with your method.

Do you have plans to build a better stand? I find the sheet metal stands are too flimsy for the feed rate possible with higher spindle speeds on these machines and only serve to add vibration.

Others may want pics... I expect YouTube video of high speed material removal! :)
 
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