What's new
What's new

B&S 618 Spindle Motor Spacing and Oriflex Oring Belts

BugRobotics

Stainless
Joined
Jun 22, 2015
Location
Denver, CO
Hi all,
I've noticed on my new (to me) B&S 618 that the spindle will slow considerably during a relatively heavier cut. I pulled the back cover off and noticed the motor mounting was a bit suspect (photo below). Maybe the original owner used some longer belts or attempted to accommodate for worn belts? Does anyone know of a different spacing used in the drive mounting setup other than what is shown in the manual (photo below as well)? I know it wouldn't look like this but want to confirm that I'm not missing a spacer between the motor clamp bracket and the motor mount plate.

B&S 618 Motor Spacer Issue.jpg

B&S 618 Motor Mounting Pic.jpg

I've ordered new #431 o-rings for the drive (please correct me here but I pulled this size info from another PM post: http://www.practicalmachinist.com/v...wn-sharpe-618-micromaster-useful-info-317978/). To replace the o-ring belts is the recommended procedure to remove the spindle or the motor (I will probably have to remove the motor anyway to fix the spacer issue but good info for others)? Spindle seems a bit less fussy just due to weight but wanted to hear from others who have done the swap. Thanks!
 
Those spacers should not be there. Some hero tried to get some more tension on the belts.

Those o-ring drive belts are pretty cheesy. You just cannot take a heavy cut with these grinders. They did make a direct drive version, but they seem to be rare.
 
Actually, the manual does show a spacer. It looks like the spacer should be equal in thickness to the steel strip that is bent up on the ends to hold the motor.
 
Actually, the manual does show a spacer. It looks like the spacer should be equal in thickness to the steel strip that is bent up on the ends to hold the motor.

Yea, I have those. My manual shows an isolation pad (long gone on mine)in the space created by the spacers. I'm assuming you are referring to the round spacers around each screw mounting the motor shown in the two pics in the first post?
 
Installed the #431 o-rings today and they fit nicely. I also removed the two improper rectangular spacers shown in the first post.

Replacing the o-rings was straightforward:
1. Remove the back cover from the upright
2. Remove the two screws directly below the spindle housing that attach the Z axis guards to the spindle housing and slide the guard down
3. Loosen the four cap head screws that attach the motor to allow the pulleys to pivot a bit
4. Now the old o-rings can be removed and replaced
 








 
Back
Top