Steel brake drum 'turning'

RockHillWill

RockHillWill

Well-known member
I have been advised that I should consider have the ID of steel drums 'ground' as opposed to having them turned in the contemporary manner. What is the necessity of this and where would I go to get this done.

I am building an axle/drive assembly that will allow both machining of the hub flange and the ability to turn it around in a lathe after the drum has been assembled to the hub to perform the turning/grinding.

Any suggestions? Thanks.
 
I saw your first post on this subject. What exactly was the reason for grinding? I can see some special caution required for the first cut on standard drums as the surface is very hard from the rolling process. I'd really like to know the theory behind that recommendation.
 
I can see the grinder being better and more accurate, but I would think a good cutter with the proper depth cut would do fine also. When I worked at the dealership cutting drums I'd run into hard spots on some of the cast iron drums and would have them ground. I wonder if flex of the steel drums enters into the reasoning.
 
Marco Tahtaras said:
I saw your first post on this subject. What exactly was the reason for grinding? I can see some special caution required for the first cut on standard drums as the surface is very hard from the rolling process. I'd really like to know the theory behind that recommendation.
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I didn't have an opportunity to do any steel drums when I had my brake lathe, but based on my experience with cast drums and as a machinist, my take is that grinding will offer the best chance of removing the minimum amount of metal. In addition to the normal work-hardening of the drums during manufacture, there will also be even harder spots caused by friction heating. My brake lathe had a toolpost grinder to use on cast drums with bad hard spots, and I imagine steel drums with hard spots would be even worse.

The alternative is to try to get under the work-hardened surface, and even harder spots, but this requires the removal of quite a bit of metal. I would guess that grinding a steel drum rather than turning it might save as much as 0.010"-0.015" of drum wall thickness, maybe more. That can easily make the difference between a salvageable drum and junk.

Joe
 
I was told that one of the reasons was that the 'machined' surface of the drums would tear at the lining, and that the ground surface would be less abrasive to the lining. Since I posted this morning, a contemporary brake service man thought that with the newer machines and better quality cutters, 'machining' the drums would not be an issue.
 
In the 50's I watched a brake job done on an A at a machine shop. The mechanic was a former Ford dealer mechanic. He used a grinder to turn the A steel drums but did not use it on cast drums. I noticed what he did but didn't ask why the difference. I assumed because of the hardened surface.

I have never turned steel drums and if not good enough to use without turning I find others. Since they will fade at full thickness they can only get worse if thinner. I suspect this is one of several conditions that contribute to the poor brake complaints.
 
Will,
We tried turning one along time ago, even with the rubber band on it, it was
a "singer". I was thinking that a Dumor grinder on the lath would be better.
FWIW
 
Will,

I have turned 100's of steel drums on the brake lathe without a problem. The problems really arise when the carbide insert on the cutting tool becomes chipped or dull. You must use a rubber silencer also. Any experienced brake mechanic should be able to help you
 
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