Can anyone describe a method for cutting a key-way on a prop driver for a non-tapered shaft? I would appreciate any comments/ideas you may have. Thanks

near the end of this thread: http://www.rcuniverse.com/forum/m_3217516/tm.htm i posted my simple method that doesn't require any special tools. if it's not clear then feel free to ask for a better explanation...



dave

Thanks Dave, but I would prefer not to permanently alter the engine in any way. I have a lathe and mill so if you know a method using either of these that would be cool. I just can't find any square drills.

i guess a mill would get you part of the way there and then do a lot of filing....

or a keyway broach in a press. if you can't get access to this then rigging up a piece of rectangular tool steel in the drill press will work for an aluminium hub. do a google image search for "broaching" and you'll get tons of ideas.



dave

Maybe a couple of jig saw blades welded together, to achieve something like this pic. I could hold the cutter in the mill and run it up an down by hand, I would have to put a taper on the back of the blades and make a couple of inserts with progressively shallower slots for deeper cuts.

.

Hi Rupurt,
I have done a couple of flywheels, because I needed to relocate the coil. This required a new keyway to restore correct timing. I clamped the flywheel in a vise and cut a new keway with a small rectangular swiss file. Marki first of course and carefully cut it nice and streight. I even did it to a cast in steel insert.

Dave

use lapping compound on the fly wheel and lap it on the shaft and you dont have to use a keyit worked for years on my briggs &stratton go-kart engines (12000rpm"s)[X(] good luck

I use the lathe as a broach. Even works on tapered holes. Grind a toolbit so it looks like a cutoff tool. put it on it's side in the tool holder and shim it up so it's centred with the chuck. Lock the chuck. run it in and out of the hole, backing out the crossfeed a few thou. at a time. Grind the toolbit so it's the same width as the woodruff key your going to use. Takes a while but does a nice job.

Flypaper, thanks that sounds like less work.

"use lapping compound on the fly wheel and lap it on the shaft and you dont have to use a keyit worked for years on my briggs &stratton go-kart engines (12000rpm"s) good luck " the shaft is not tapered so this is not likely to work for me, thanks anyway.

Dave, A swiss file, is that like a needle file?

I agree with FLYPAPER, that is a good cheap method and works really well in aluminium.
Making sure the tool is at the correct centre height ( centre of the bore ) is important, also make sure the chuck can't move at all!

The same thing can be done on a mill by moving the quill up and down and feeding the table slowly.

Bruce

Bruce I was thinking the same thing, it would be a little easier to setup.

Rupurt: Is this non tapered shaft a part of the crank or what? What kind of engine are you working on? Can you post a photo...I am wondering just what you got there? Thanks Capt,n

Hey Captin, The engine is a ASP 160twin. The shaft is not tapered and I am going to make a prop hub to convert to CDI. Here is a pic of the part I am drawing inspiration from. And a pic of the crank both are from global hobby's site

One more vote for flypapers method, I use a similiar method for grooving prop driver faces, though its gonna take a bit of time getting the depth for a keyway with this method, its a good accurate technique

Thanks I think that seems like the best way to go, I may use the mill though it just seems like it would be easier to set up. I was thinking of grinding an old endmill for the job, do you guys think a collet will hold it tight enough, the one I have in mind has a 16mm shank, would it be safe to put a piece of aluminium behind it in the collet to stop it sliding back

Crusty should I use a twin turbo setup or should I put both exhaust through one turbo

I tried it out on the mill works great only takes a couple of minutes to cut a slot, I now need to come up with a plan to lock the spindle. The collet had no problem holding the tool. Thanks for your help guys, I will post a pic sometime soon[8D]

Is a hand broach very expensive?

Bill

Well it's not pretty but here it is. The practice runs where promising with some refinement I think This could produce some professional looking key-ways.

Bill, Here they aren't cheap.

Rupurt....why don,t you use the prop hub that came with the engine. Just install a tiny magnet in a small hole drilled in the hub. Then position sensor to pick up timing.