Varispeed VFD conversion

[DSE]

I have boss 5 CNC with a noisy head (the spindle is ok). Since I have a VFD to control the spindle speed, I'd like to replace the vari-speed with a V-pulley set up. Does anyone of recommendations or lessons learned on doing this? Pictures are always good.

Thanks

[mactec54]

Hi DSE

Yes this works great I have done many of these 1to1 & 1-1/2 to1 I have also removed
the low gear on some I will try & do some Photos of my setups I have cut up to
5" out of the top of the machine & it can run it at 6,000 rpms

[Al_The_Man]

I replaced the vari-speed on my two Excello's with timing belt/pulleys, They have a gear box with 1:1 & 6:1 speed, which is useful for the low rpm needs, I went 1:1 on the motor to spindle shaft and run the existing 4 pole motor at 120Hz for x2 rpm.
Al.

[Dennis Storzek]

I just did likewise on an old BOSS 6 that had a clapped out Vari-drive that had eaten the motor shaft. The BOSS machines have a very squat motor with an eight inch long shaft, not one that was going to be cheap and easy to find. Anyway, I wanted to increase the top speed to 5k.

I picked up a 3HP Reliance motor new in box on e-bay for less than new vari-speed disks would have cost. I went 3HP because I'm running a 1:1.5 pulley ratio to increase the spindle speed, so I don't have to drive the motor more than 120hz to get my 5k. If it lacks torque on the low end I can always change to a 1:1 drive (pulley centers will be the same) but then I'll have to drive the motor to 5k also. The new motor was too tall to fit under the belt housing like the original, so it's mounted on top like on a manual 2J head. This way, the stock shaft length wasn't a problem. Works great, but if it had to go in a basement shop I'd be in trouble with mama; I'd have to cut a hole in the first floor and cover it with a drum table. The darned thing is now 8'-8" over the top of the motor and barely fits under the ceiling in the shop at work.

"L" series timing belts are rated 6HP per inch of width; I had room for a 1" wide belt, so used that. A 24 tooth pulley was the smallest that would fit the spindle shaft, so I used a 36 on the motor, and an 80 tooth belt put the motor back in about the same location it was, the aluminum adapter plate has slotted holes for fine tuning. If I want to go to a 1:1 ratio, two 36 tooth pulleys and an 84 tooth belt will put the motor in within .020" of the same place. So far I haven't felt the need, but haven't done much work down around 500 – 600 RPM, so time will tell.

Dennis

[mactec54]

Hi DSE
I do not use the timinig belts as they use more power to drive them
I use a polyVbelt as you can see in the photo all my parts I custom
designed & make it has many changes to the head from the Boss 5 it
was. It has about 4'' out of the top of this Mill

[DSE]

I was thinking of using pulleys like this except with v-belt like mactec54.

mactec54,
Very impressive work. I guess that must be an electrically operated brake?

[jacampb2]

Originally Posted by mactec54 Hi DSE I do not use the timinig belts as they use more power to drive them I use a polyVbelt as you can see in the photo all my parts I custom designed & make it has many changes to the head from the Boss 5 it was. It has about 4'' out of the top of this Mill

That is sweet, and just at the right time. I am converting my b'port series 1 cnc boss4 to vfd and mach 3. Just broke one of the varispeed sheeve halves and was looking at doing a 1:1 conversion...

How is the belt tensioned in your setup?

Later,
Jason

[mactec54]

Hi all
How to tension the belt I sloted the motor housing were it mounts on both lugs
the pulleys are then made to size so the belt will just fit on & with the slots
in the motor mount you can ajust the belt

The brake is air operated double acting & has return springs to keep the pads free
of the disc this is operated by the software or a manual switch on the side of the head

[alex 850]

I have a series one boss 5 .I am going to do the same thing you guys have done. I am sick of the noise and the bearings are geting loose again after the last build. Good to know that it can be done.
alex

[alex 850]

I am getting ready for the convesion on my series 1 boss 5, it is an 80s model.If some one can tell me what pulleys,belts,and a tensioner i need for this model would be most helpful ,and apreciated,and where to get it.
thanks alex