Key way broaches and sizes

[Jasonb]

MB I've done plenty of keyways using the lathe carrage, your biggest problem will be the small size of the bore as the absolute max tool holder you could use is going to be 9/32" to allow 1/32 tool projection. This will tend to flex alay from teh cut quite a lot but with patience and 0.001 depth of cut you can do it

Your 9x20 will be upto it I did most of mine on an 8x24 Emco which the imports are copied from, this is a steel gear centre, four 3/16" keyways 1" long and I don't have spindle lock.

The shaft keyway is easily done with an endmill or slotdrill, this is the matching shaft with keysteel soldered in to form a splined shaft.

For a small 1/16" keyway you could well be able to press it in using a bench drill though I would not use it on anything over 1/8 as it could strain the rack. I have seen larger ones done by puting the flywheel over the edge of a bridgeport table and raising teh table onto the broach pressing under the arm.

Another option that would work is to bore the flywheel oversize by 1/16, turn up a sleeve to fit the flywheel and shaft then cut a 1/16 slot down the sleeve. This can now be silver brazed into the bronze flywheels or locktite into the iron ones. The Minnie traction engine in my avitar uses this method on 9/32" shafts.

J

 

[arnoldb]

Just a thought...

Could you pre-drill the area where you want to broach the keyway in the flywheel with a 1/16th (or slightly smaller) drill ? - That will leave less material to remove while broaching.

Regards, Arnold

 

[Maryak]

To expand on Arnold's comment-Why not use a round key and drill/endmill/ream the shaft and flywheel together. ???

Hope this helps

Best Regards
Bob

 

[Metal Butcher]

Thanks Jason,Arnold, and Bob for even more good ideas of ways to secure my flywheels.

Plan A: I was trying to get the winning bid on a set of Dunmor broaches that the E-bay seller claimed was new, but based on the pictures shown, and looking them over, and over, I started to have some reservations, and stopped my biding way short of the $110. winning bid.

http://cgi.ebay.com/ws/eBayISAPI.dl...2F6QLjw%3D&viewitem=&sspagename=STRK:MEWAX:IT

Plan B: After wards I made the decision and purchased the same Dunmor Minute Man KSB-08, #00 size boxed set of broaches and bushings from Amazon, new w/warranty for $20 more. There were 2-left when I made the purchase, and when I refreshed the page it showed only one left and the price went up by $22. What was that all about?

I was thinking of getting the lower priced import set (about $90 w/ship) that I'm sure would have been more than adequate, but "Honey" got involved and insisted by saying, "I don't want to hear about how you would fire the person responsible at the factory that made them!" With the current economic situation this country is in, I feel that I just made a small donation towards our economic recovery.

Honey knows that I can be critical at times, so what could I say? ;D

-MB

 

[Metal Butcher]

I forgot to ask you to take a good hard look at the pictures in the E-bay link I provided.

On the out side of the box it looks like half the factory label has been cut away. There are two added pieces of tape with some sort of numbering or lettering that doesn't belong. And it looks like all that's left of the latch is the pin. I know the outside doesn't really matte,r but the listing says "brand new".

On the inside the bushings don't have a new consistent look about them. Only one of the broaches, the one in the middle is in a red capped container. There also some pieces that appears to be key stock in the upper part of the box. Both pictures are out of focus, with over 600 feed back you would think this seller would have learned how to take a focused picture. For something that's claimed to be "brand new" and never been used, this all looks a little fishy to me.

http://cgi.ebay.com/ws/eBayISAPI.dl...2F6QLjw%3D&viewitem=&sspagename=STRK:MEWAX:IT

Maybe I'm wrong. What's your opinion?

-MB

 

[MachineTom]

I've a set of Dumont broaches but the smallest A size broach I have is 1/8 keyway. It is very simple to make a bushing to fit the broach and with 10 to do don't fool around with the lathe, or mill, buy a broach. (I'll lend you the 1/8 if you would like). An A broach needs a groove milled into the bushing of .205"d x .128"w regardless of the keyway width, The bushing should be the lenght of the keyway to be cut or more. The max lenght of cut is 1.125 you can stretch this some with cast iron, 25% of so.

The broach will fit about 1/2-3/4" into the flywheel before the cutting, it begins to get stiff at around 1" in depth. A trick to avoid bending a broach, is to push 1/2" in, then release pressure, press another 1/2" repeat, this will take care of slight alignment issues as you push the broach.

 

[Metal Butcher]

I've a set of Dumont broaches but the smallest A size broach I have is 1/8 keyway. It is very simple to make a bushing to fit the broach and with 10 to do don't fool around with the lathe, or mill, buy a broach. (I'll lend you the 1/8 if you would like). An A broach needs a groove milled into the bushing of .205"d x .128"w regardless of the keyway width, The bushing should be the lenght of the keyway to be cut or more. The max lenght of cut is 1.125 you can stretch this some with cast iron, 25% of so.

Hi Tom. Thank you for your generous offer to lend me your broach. Yesterday I ordered a #00 Dumont set . Its the small precision set that cut's 1/16", 3/32", and 1/8" key ways. This set will cover my immediate needs, and hopefully all my future needs for building small engines.

-MB