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Whats inside a Brake Dresser?

Peter Neill

Stainless
Joined
Apr 30, 2006
Location
Suffolk, England
The ones used for truing a diamond wheel?
Obviously something to limit speed, so is it just a shaft with a couple of bearings and some sort of adjustable friction brake?
 
A number of tear-downs on YouTube.

Basically a spring governor. As the rotation speed increases, pushes a set of bronze wear-rings against the circular housing (like a drum brake on a car).
 
Three bronze brake shoes running inside the back cup.
Spring loaded, you adjust speed by tightening or loosening the screw changing the spring preload
Eventually the shoes wear far enough to no longer sit in their retaining square and spin sideways locking the whole thing up.
Units that have not been used for a long while need to have the shoes removed and the sliding section and hole cleaned or the don't fly out as the should.
Sometimes you also need to resurface the inside of the cup like a worn brake drum.
Bob
 

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As stated its a pair of Bronze shoes, with springs in the center that are adjustable. Shaft spins Wheel oln one end, shoes on the other.

Recently came upon a site that sold Grinding wheels, as well as the dresser and repair parts. Of course I can't find it again, It was maybe Nortons site.

Norton Brake Controlled Truing Device is exact name
 
Norton sells a kit of new shoes, springs and bolts.
Most off brands are clones so the parts fit but if you have a older Agathon grinder they do not.
You can only cut the cup lightly or it gets too big and the shoes rotate so be careful here and go for partial cleanup. I have never seen replacements for the cup.

If you are looking to build one from scratch I'd build a motorized one rather than a brake device.
Works much better but does eat up more real-estate.
Bob
 
Thank you, for the explanations, and the pictures.
I do need to build one, but it will a fairly infrequent use item so may skip the motor.

One more question if I may - what is the approximate clearance at rest, between the bronze shoes and the housing?
 
Peter-

Not surprised you can't find it. I had a devil of a time remembering where I saw it even looking through my history.

The channel is Cape Cod CNC. The video is titled Precision Toolroom Stones. The brake grinder tear-down is late in the video (around 35:00). 629 views and only 113 subscribers. YouTube is a beautiful thing.

Cheers...
 
OK, so the brake truer causes the truing wheel to rotate at some speed less than the wheel being trued, but not zero.

But which way does a motor turn? The same way? The opposite way?
 
The same direction just as a brake device does.
I do have reversing switches on many of mine but you only run "against" the wheel in special cases and then normally finish up going with the wheel.
Bob
 
Here's a video from "The Grinding Doc" giving some insight into powered diamond wheel dressing (including "with" and "anti" directional).

YouTube

Replying to myself to correct one aspect - this is for using a diamond dressing wheel on a powered dresser to profile or surface a "normal" abrasive wheel, not the same application as using a brake dresser on a diamond grinding wheel.
 
Here's a video from "The Grinding Doc" giving some insight into powered diamond wheel dressing (including "with" and "anti" directional).

YouTube

As much as I like Jeff as you noted this does not apply here in any shape or form.
This video is using a diamond dressing roll on a standard white, blue, pink, steel grinding wheels. Apples and oranges.
You will not fracture the grains in a diamond wheel.

Truing or dressing a diamond wheel is about ripping entire grains out to get your shape and then leaving the correct "open" bond tail to support the new diamonds.
Sometimes after the dress you will want to "dull" the diamonds to achieve a higher surface finish or reduce edge chippage while giving up cutting speed. This is an added step.
We use hand held moly sticks, CBN and PCD to do this.
Bob
 
I'm rebuilding a brake controlled truing device (norton copy) that is barely worn, but was made with open bearings that were totally locked up with grit. I've done a lot of searching and can find no maintenance information online. I cleaned out what looked to be grease from the brake drum. Does anyone know if the brake rotor, shoes or drum should be lubricated? I think not, but the presence of lube in the unit makes me wonder.

I've more or less gotten everything else figured out. Will be installing new sealed bearings.

Can anybody offer wisdom or maintenance advice for the brake?

Many thanks,

Don
 
Nobody with any thoughts regarding post above? I've really looked and can find nothing. Mostly I'm just curious if the brake is meant to be lubricated, and if so, with what?
 
No lube, dry.
Don't let water get in, gums it up.
When used wet we seal the drum and attachment screws with silicone.
Maintenance is just clean it from any dust/dirt build up.
Speed is controlled by seating the shoe screws and then backing them off from a bit to a bunch.
Yes, the screws are not seated tight, floating out there providing the correct spring force on the shoe.
Bob
 








 
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