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Thread: Broaches

  1. #1
    METALARCHER Guest

    Default Broaches

    Can some one explain the nomenclature of keyway broaches? I see the dimensions and understand that as well the width but what are the "a", "B" or "C" designations?. How long a stroke do they require from a press.

    Since I am just stocking up for future "maybe" needs after retirement, what would be agood set? Been looking at some from Grizzly or Enco.

    Thanks

  2. #2
    Join Date
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    Default

    I am not an experienced user, but will soon be one as I have just ordered a keyway broach and bushing for one particular size. It is a bit confusing and definitive information is hard to come by. One thing is clear, the A, B, C, etc. designation of the broach and the bushing must match or it will not work properly.

    What I have discovered is that the width of the key a broach will cut and the width of the broach itself are not necessairly the same. The part of the broach that rides in the bushing can be wider. This can have several advantages and I am not sure which of these is the real reason for this idea. The first one that comes to me is that a wider body on the broach would make it harder to break. It is also possible that a single bushing of a given diameter could be used for several different sizes of keyways, thereby saving some money by reducing the number of bushings needed.

    As for the stroke needed, different broaches will need different strokes. Some suppliers list these dimensions better than others. There is a pilot area at the start end and another area at the large end so the stroke is somewhat less than the overall length. Some listings do give the length of the cutting area, but I would think you would need a bit more than this on your press. But I don't know exactly how much. There are some extended height arbor presses and the floor presses have a lot of adjustment range. If the stroke of the cylinder is limited, you could use spacers to extend it in a larger press.

    I hope someone can further clarify this with some specifics and recomendations from experience. I should have some limited experience in a few weeks or so.

    As far as buying them, you may want to look at MSC. I found they presently have some good prices and they seem to have a "special of the day" thing going on presently. I just got about 30% off and free shipping on my order.

    Also do an internet search on "broach". I got some good hits but didn't have time to read all of them.
    Paul A.

    Make it fit.
    You can't win and there is a penalty for trying!

  3. #3
    METALARCHER Guest

    Default

    thanks, will do more research.

  4. #4
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    what press do you have? the A/B/C/D/E irrc are like a form factor that determines the length of the broach and slot width of the bush, ie a bushing for an A series will work with any A series. by the time you are getting to C, they're 12" long and dont fit many arbor presses

    oh yeah, the other thought is buy quality ones. standard advice for any cutting tool and broaches are particularly delicate
    Last edited by Mcgyver; 10-11-2009 at 02:27 PM.

  5. #5
    Join Date
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    Default

    I vote for DuMont Minute Man broaches. Enco part number: 422-1484.

    It's a little pricey, but it handles a wide range and will last a long time. Like McGyver says, the A,B,C, etc designations pertains to the size of the broach. The idea is: you don't need a complete set of bushings for each size broach. Instead, you get a set of bushings that handle several different diameters, but each bushing can generally handle 3 or so different sized broaches.

    I'm not sure I explained that very well...in any case, it's not horribly important. They are somewhat standard - i.e. the small sizes, .125 and less are A. .125 to .1875 are usually B, etc

  6. #6
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    Smile

    One thing that I have found is. You will need a press with at least 18 inches of stroke . The wider broaches 5/16 and up 3/8 ,1/2 are 12inches long and to have working room getting broach in to part and part under press about the min. is an 18 inch stroke press. I use a Drake 1 1/2 B, 1 1/2 ton .

  7. #7
    METALARCHER Guest

    Default

    Thanks for all the replys! I have a hyd press with an adjustable bed so I can use various blocks to give a long stroke.

    Some where I saw a homemade setup that pulls the broach through the part. Might be fun to fool with.

    Like i said, this is a retirement type hobby fro me. Just trying to get as fully equiped as I can now while I'm still on a payroll.

  8. #8
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    Along with what Lane said -- even the small set/s like this one I got from ENCO ......
    http://www.use-enco.com/CGI/INSRIT?P...&PARTPG=INLMK3

    wont even fit in one of the common 1 ton Chinese presses you see every where (at least the one I got) The throat depth is 5" and the length of the broach is 5" --- In fact I havent found much that that little press will do - I still use my big old bench vise mostly for those type things. A good press like Lane talks about is on my wish list.
    If everything seems to be going well, you have obviously overlooked something........

  9. #9
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    I second Fasttrack's recommendation. I have the #10-10A combination set and although I haven't used it much, for what I did do, it performed well. I wish I had the #20 set which includes the 5/16 broach. It takes a lot of pressure to push a broach through a thick hub (more teeth on the broach cutting) and I found I had to do it in steps since all I have is a 10 ton portapower ram on my press. I made up spacers and such to use a much smaller broach first so I wouldn't be removing as much metal. PITA. Broach sets are nice toys!

  10. #10
    Join Date
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    The A, B, C & D nomenclature refers to the broach's physical dimensions, more specifically, the width of the broach itself. An A broach is 1/8" wide, B is 3/16", C is 3/8" and D is 1/2" .

    Each style includes several different broaches of different widths, producing different width keyways. The length, number of passes and shims required depends on the width and depth of the keway being cut.

    http://www.dumont.com/prod2c.html
    Jim H.

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