BG-272 Belt Release Lever

For some folks, reaching over the grinder to push down with 30 lbs force in the tensioning pillar can be a pain. After taking a look at what Mike Lang did with his build, I thought I would put something together that is adjustable, doesn't require any welding and can be easily retrofitted to existing BG-272 style builds. 

Before I painted. This is the prototype. It should give you an idea of how the lever operates.


16" of  1/4" x 1" flat bar
4" of 1/4" NC threaded rod
2 ea  1/4" x 2-1/2" NC hex head capscrew (bolt)
1 ea  1/4" x 1/2" NC hex head capscrew
1 ea 1/4" NC nylon locknut
5 ea 1/4" NC hex nut
7 ea 1/4" flat washer
Thread lock (locktite)


Permanent marker
Punch & Hammer
1/4" Drill bit
13/64" Drill bit
1/4" -20 (NC) tap
Cutting fluid
Hacksaw or metal cutting band saw
7/16" wrenches (2)

NOTE: The holes shown in red are tapped to 1/4" NC. 

Scribe a center line down the 1/4" x 1" bar stock.

Mark and cut items A, B, C and  D from the 1/4" x 1" bar stock as squarely as possible.

Mark and punch holes as shown in figure below.

Drill 1/4" holes (5) as shown.

Drill 13/64" holes (3) as shown in red.

Tap four 13/64" holes to 1/4" -20 with tap and cutting fluid.

Clean and paint.


Cut 1/4" NC threaded rod to 4", finish cut ends for ease of threading. Thread on two hex nuts and jam (lock) them together.

It is highly recommended that you use 0.25" wall HSS for your tensioning and tracking pillar. This is because the bolt that connects the lever to the pillar will need enough wall thickness to make a solid threaded connection.

If you used thinner wall HSS, you can drill straight through and use a longer bolt.

Here we have part A and B loosely assembled with the 2-1/2" capscrew and the threaded rod.
Part D and part C are setup. Use some locktite in the tapped hole. Lock the two nuts together to make snugly fitting, but still movable bolt. Add a drop of assembly lube. The two pieces should move freely, but not be sloppy loose.
Again parts D and C, side view.

For the handle I drilled out a 2-1/8" section of 3/4" wooden dowel and used the second 2-1/2" capscrew with two flat washers to secure the handle to the handle arm. This threads into handle arm with a drop of locktite and is tightened.

For assembly reference, this image shows how the release lever is built up before installing it on the grinder. I mocked it up on the bench for illustration.

Stand off the handle arm with one nut and one flat washer. Add a drop of lube. Now attach the handle arm assembly and secure with a washer, nut and nylon lock nut.

Thread the bolt into tapped hole on pillar. Add a drop of locktite, tighten. Tighten the clamp on to the grinder frame.

If you have any questions, kindly let me know.

Here's a belt tuning video I did that shows how the release lever can be used to quickly apply different belt tensions.

Happy grinding!



Unknown said...


D. Comeau said...

Thanks Mike!

Unknown said...

Hello Dan,
You do not remember me, I've written you some months ago about making the wheals and the drive wheal on a 2/72 belt grinder out of hard wood. Just by chance my father has not thrown out my old roller-blades so I got my hands on 10 still decent ball bearings.
I'll use some hard skateboard wheals for the grinder.
The motor is a washing machine 2 poles 50Hz 220V motor good for 400W or 0.71 HP, back in 1973. It spins at 2980 RPM maximum and I am thinking of using the motor without a drive wheal. What is your opinion on this?
The stand for the grinder is all welded up from 30/30 millimeters square tubing on a 4 mill base plate. Will have to do a lot of cleaning on it.
Please tell me what you think of using the motor shaft to drive the belt and what is better for the tension arm: a spring or a cabinet piston?

D. Comeau said...

Hi Bogdan,

I am not certain of what you will use to drive the belt if you do not have a wheel. Can you elaborate? The motor shaft being small diameter will not have sufficient surface area for traction. I would recommend at minimum a wheel diameter 75 mm. I was able to run a belt okay on a 70 mm (2.75") skateboard wheel.


Unknown said...

I'll be taken up the option of the 1/8 scheduled 40 pipe. The problem a ran into I couldn't find pipe that size, so I'll be using a piece of DOM so I can run the 1/4 bolt at the pivot point and fabricate the handle as you did. There are no indications where to weld (measurements)