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  1. #1
    Join Date
    Feb 2013
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    Default Machining clutch friction material

    I need to cut out one of these clutch plates (7.5"OD x 4.5"ID x 5/16") from a square of friction facing material, its for a Howard cultivator, a low tech low speed application.

    Ideally I would like to do it all on the rotary table with slot drills but I suspect the material will be very hard on the cutting edges.

    Next best option is to use a scroll saw, it won't be as neat a job but scroll saw blades are very cheap.

    Any thoughts?


  2. #2
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    Looks like it could be made on a lathe, except for the 6 small holes.

    Jordan

  3. #3
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    However you end up doing it, I would think that serious thought needs to be given to dust collection, I may be wrong but I suspect that while friction material may no longer contain asbestos, the fibre reinforcement is probably still quite nasty and hazardous to health. A scroll saw would seem to be less of a dust producer and easier to set up with a shop vacuum than a mill with slot drills to do the machining, and also a lot easier to clean after the job was completed. You could even take the operation outside on a good day, and any dust missed by the shop-vac would be less of a problem than if it was in your workshop being recycled as you moved about. I agree that the material is likely to be hard on tooling, although the holes will probably need to be drilled - I imagine any attempt to punch them would likely shatter the material. A high pressure water jet may do it all, someone hopefully will chime in with the good oil. Regards,
    Rob

  4. #4
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    Hi Bob,
    Probably too late now but I had to make some plates for the line shafting clutch for the Jones and Shipman camelback drill at work.
    Needless to say, plates weren't available so I got some tractor PTO clutch plates from Bareco and as they were 'in the ballpark' in size, they needed very little machining. This cut down on a lot of tool wear etc.
    I used HSS (it's all I had) and wore a path to the grinder during subsequent re-sharpenings.
    I attached them to a steel plate with a piece of pipe welded to the back for the 3 jaw chuck, and used a parting off tool to plunge cut towards the chuck to get the right diameters. Worked a treat.

    Phil

  5. #5
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    Have cut down brake pads quite a few times with carbide. Dust, yeah, there's a bit, but I just use a paper mask and do a good clean up afterwards. Suppose a worry with something that appears to have no backing - like a pad - is how to prevent it fracturing, materials I have experience with are usually hard and brittle and you get the odd cut where you'll get a flake detaching instead of a clean one.

  6. #6
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    Quote Originally Posted by Hunch View Post
    Have cut down brake pads quite a few times with carbide. Dust, yeah, there's a bit, but I just use a paper mask and do a good clean up afterwards. Suppose a worry with something that appears to have no backing - like a pad - is how to prevent it fracturing, materials I have experience with are usually hard and brittle and you get the odd cut where you'll get a flake detaching instead of a clean one.
    If as I suspect, the material is to be bonded to the metal backing plate shown in the photo, do that first, then machine away the excess in the lathe with carbide.

    Certainly won't wear carbide to any significant degree.

    Wear a dust mask.

    Rob
    The worst that can happen is you will fail.
    But at least you tried.



  7. #7
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    I've used angle grinders attached to lathe toolposts to machine clutch plate faces.
    A vacuum cleaner nozzle placed close to the tool catches a lot of the dust.

    Jordan

  8. #8
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    Thanks for the thoughts guys.

    Tried the scroll saw but the clutch facing is way too hard for it.

    Rotary table it will have to be, I have some cheap carbide slot mills coming that I won't mourn over if they get ruined.

    I'll heed the dust control suggestions.

  9. #9
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    Thought there might have been an immediate need to do it. I know it might be less DIY and satisfying, the mobs who do this on a more regular basis water-jet the material, if there's some place nearby with the equipment, that's certainly one of the easier jobs.

  10. #10
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    Quote Originally Posted by bob ward View Post
    Rotary table it will have to be, I have some cheap carbide slot mills coming that I won't mourn over if they get ruined.
    Finally got back to this project. The good news is that cheap carbide slot drills - at least for the amount of cutting I did (1 circle at 110 dia and 1 at 190 dia) - cut clutch friction material without noticeably losing their sharpness.

    I drilled the 6 x 7/16" holes with a HSS drill which lost its edge very quickly. It still kept cutting the soft ply and friction material OK, but the drill will need to be resharpened before it goes near metal again.

    I sandwiched the clutch friction material between plywood to reduce the risk of it flaking or spalling, but now that I've done the job I don't know that I would worry about doing that next time.


  11. #11
    BobL is offline Member: Blue and white apron brigade
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    Just a word about those who want to machine stuff like this and think that a vacuum cleaner and face mask will make it safer.
    If there is any chance that it has asbestos in it you need to know that asbestos fibres will pass straight through most vacuum cleaner filters and many masks.
    Vacuum cleaners can make things worse because they make more fine dust out of bigger particles and they can quickly fill a shed up with fine dust that hangs around in the air for days and is almost impossible to clean up.
    Even vacuum cleaners with the right sorts of filters often have leaks around damaged seals and cracks in the body of the cleaner and will continue to contaminate a shed very quickly.
    If you have a vacuum cleaner that has been used to collect asbestos dust seriously consider disposing of it as it will continue to contaminate your shed for years, yes the whole vacuum cleaner and not just the filter. The motors become badly contaminated and cannot be cleaned all that easily
    Vacuum cleaners and dust collectors that are located outside a shed are the way to go for this sort of work - and seriously consider disposing of the filters after you do the work as the filter will be forever contaminated and cleanup can not be assured.
    Please also check the face mask is actually rated for asbestos (that's a P3 mask)

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