Broaching Question

I'm hoping that my limited understanding off how the broaching process works will help me find an answer. I'm lookin gfor an inexpensive way to create a
gear shift lever. My thoughts are to have a broach (if that's the right name) made up and then utilize a press at work. People I have talked to have suggested that using a milling machine would be the better way to go, but that's not something I have access to. My quantities will be very low, so the cost of having a broach made up may not be worth it. Now, here's my application, I want to make motorcycle hand shift levers similar to the one in the pictures below:
http://tinyurl.com/639ur
This one was made by cutting a stock foot lever and welding on the additional peice that the extension screws into. Unfortunately this method proved to be a little too weak, the last picture is the bike on the side of the road with the broken lever. What I'd like to be able to do is to make the small peice that attaches to the spline and I thought that the center part could be made using a broach.
I guess my question, aside from wondering if this is doable, is whether or not there's a company around that would be able to make such a broach, or am I totally off base on how the whole process might work? I located in Canada if that makes a difference as to what companies to recommend.
Thanks, Tony
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Tud wrote:

I couldn't see the number and size of the splines in the part in your photo, but I'd say that broaching is the way to go, particularly if they are rather shallow cuts. Probably best to leave cutting the clamping slot until after you do the broaching.
Are you planning on making these for just one make and model of bike? Are the shifter shafts the same size on other bikes?
Just Googling up "broach" will get you plenty of manufacturers who will give you a quote for what you need, once you send them a drawing of your part and tell them what the material is. Be aware that you will probably suffer sticker shock when you get the price.
Frankly, I'm a bit dubious about your being able to come up with anything along the lines of what your photos show which will take the strain of a few unintended hard pulls, pushes or knocks without failing somehow. I think you putting just too much leverage on a small splined shaft, but YMMV.
Good luck,
Jeff
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Jeffry Wisnia

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Jeff Wisnia wrote...

I don't have the number on hand, but they're definately not cut very deep.

I was planning on making just one size, fortunately it will fit serveral makes and model years of older Triumphs, and possibly other British bikes.

Yeah, I'm guessing the price may stop me dead in my tracks.

You're likely right, my plan is to use aluminum to limit the weight on the spline and make the end around the spline beefier than the one in the picture.

Thanks, I'll google for some manufacturers.
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Tud wrote:

For a low-volume application, I'd look for a heavier lever on another make of bike that has the same splines and enough material to cut, drill and thread for the handle. Then buy new levers to modify. I bet that would be cheapest.
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Rex B wrote...

Thanks for the suggestion, I'll do some searching to see if I can find a compatible shifter as an alternative.
Tony
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Perhaps another tack would be to have the pieces cut by the wire EDM method. A CNC wire EDM machine should be able to crank this part out, including the clamping slot in short order.
This suggestion came to mind because at the last Meeting of the New England Model Engineering Society our speaker was Bob Bouley ,an application engineer at Methodes Machine Tool Co. in Sudbury MA. They specialize in Wire EDM and have, as I recall him saying, about 80 machines on the shop floor.
A big advantage of this method is that there is no tooling cost for you. You would just have to provide a drawing and they could take it from there.
Errol Groff
Instructor, Machine Tool Department
H.H. Ellis Technical High School 643 Upper Maple Street Dantieson, CT 06239
New England Model Engineering Society www.neme-s.org Pleasse note our new URL
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Errol Groff wrote...

I'm no machinist, so I'll admit that this is the first time I've ever heard of that, so you've given me something new to look into, thanks for the info.
Tony
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To be blunt, I really didn't see anything in your photographs that would lend itself to broaching. Perhaps you can explain.
Do you understand what broaching is, and some of the applications where it is typically employed?
Were I you, I'd stick close to someone with a milling machine.
Harry C.
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Harry wrote......

Not entirely, I'm green when it comes to metal work. I was thinking that broaching would be the process of pushing a tool through the part of the shifter that would fit over the splines of the shifter spindle in order to cut the corresponding splines. I could very well be mistaken.

Thanks, I've been given some areas to research that may be an alternative to broaching that I'll follow up on.
Tony
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snipped-for-privacy@yahoo.com wrote:

He's looking to broach the splines in the hole that mounts to the shift lever. Broaching is appropriate there. Forging over a mandrel would work too.
Cheers Trevor Jones
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Tud wrote:

Make part , heat red hot , slip over spline die , squeeze with a mold using hydraulic jacks for pressure , cool off part and clean it up ? Forging seems ideal for this . Luck Ken Cutt
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I've done something like this to make some about 12 adapters to fit non standard knobs to water taps. I made a one pass push broach from silver steel. The tap spindle had what I think is commonly termed a serration like what you probably have on the bike spindle, on examination the angle between the teeth was 90 so I turned up a blank to the OD and set it in a indexer on a BP. Using a sharp end mill I cut the broach, checking it dimensions with wires and comparing to the one on the tap, I left it maybe .002" over initially. I left the set-up on the BP until I tested the resulting broached result. After hardening and tempering I placed the broach in a flypress with the adapter being held underneath in a 3 jaw. Use of appropriate cutting fluid helps quite a bit. The first result was slightly large so I made another maybe 0.001" smaller which I was happy with, this was easy as I had left the set-up alone on the last setting. Making the whole broach probably took about an hour and this method may work well for the limited numbers you require.
Tud wrote:

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