What's new
What's new

Internal spline, how to do it?

Theo

Plastic
Joined
Sep 30, 2009
Location
Achaia, Greece
Hello everybody. I have a project here. The part is an adaptor to connect a bike engine's gearbox output shaft to a propshaft. The material of the adaptor have to be a strong alloy steel, like 4130.
I attach a couple of images of the adaptor. The part is fairly easy to machine, but the hard thing is the internal spline at the center which needs to slide over the splined output shaft of the engine.
What's the most economical way to do this internal spline? Wire-EDM perhaps? And how to design the exact shape of the spline? I need to replicate this internal spline exactly!
$(KGrHqZ,!o!E-z8oTSwWBQB9T7Wrqw~~60_35.JPG

Any reccomendations? Thanks! :)
 

Attachments

  • 1.jpg
    1.jpg
    83.3 KB · Views: 1,266
  • 2.jpg
    2.jpg
    81.5 KB · Views: 1,239
Hi Theo,

EDM should work, I think, but possibly expensive for a single part. Otherwise you'll need to find someone with the right broach (unlikely) or someone with a shaper. I'm sure there are a number of folks on the board that would quote it for you if you'd like someone else to make the part or put in the spline on a shaper. PM me if you'd like to discuss it.

If you really want to do it yourself and you have a lathe, you can use your lathe as an indexer and shaper. This is a pretty rough way to go, but I'm sure you can find threads about that here or on other boards.

Ryan
 
I guess it depends a lot on what machines etc you have at your disposal, if you give us an idea what you are working with or what your possibilities are we could answer more comprehensively
 
If i ship the sprocket to someone who knows what to do, do you think it's possible to make the broach for me? And what would be the cost?

edit: I certainly cannot do it myself.
 
For a one off I'd be sorely tempted to use the existing sprocket and weld or bolt this to the new hub.
A broach would cost probably $1500 to $2000 for a one off, another way would be to have it gear cut on a fellows or maxicut with an internal cutter.
Less spendy but you need someone who has both the machine and cutter
 
For a one off I'd be sorely tempted to use the existing sprocket and weld or bolt this to the new hub.
A broach would cost probably $1500 to $2000 for a one off, another way would be to have it gear cut on a fellows or maxicut with an internal cutter.
Less spendy but you need someone who has both the machine and cutter

The most tempting is to weld the internal spline section of the sprocket on to the adaptor!
But i don't know the exact alloy type of the sprocket. How can i find it?
 
The simple solution is to check with some job machine shops in the area and see what they can do. You aren't in production with this part,you just need one. If the job shop has a shaper, and they have a machinist who knows how to use it, that would probably be the cheapest route.

There is a job shop near me that I go to when I run into a wierd problem - they have many years of experience, they run into challenges every day, and they know all the local specialty shops. They are kind of a machinist's rescue squad
 
Don't worry about getting it done until you know about and can exactly document the male spline. Everyone that can do it will need that information before they ever think about how much it will cost or if they can actually do it.
 
Hub City Inc -
companies like that make splined blanks, which are readily welded to whatever you want. but will be hard to find the right one in motorcycle sizes.

welding the sprocket you show is also doable. but it's heat treated and you may crack it off, or certianly ruin the heat treat at the splines.

HOW ABOUT THIS: see all those holes in the sprocket? use them to BOLT and/or PIN the sprocket to the side of your part.
 
The most tempting is to weld the internal spline section of the sprocket on to the adaptor!
But i don't know the exact alloy type of the sprocket. How can i find it?

Doesn't really matter what the steel alloys are as you can weld dissimilar alloys with 308ss rod or even better Hastelloy W rod.

Looks like you are putting a bike engine in a shaft drive minibuggy. If so, I HIGHLY recommend you check out this website. These guys have tons of experience with this:

MiniBuggy.Net: The Ultimate Off-Road Buggy Community
 
why weld, you've got 8 holes and an internal taper to locate. Bolt the parts together.
With welding, you always have to worry about cracks if the part was heat treated.,
JR
 
why weld, you've got 8 holes and an internal taper to locate. Bolt the parts together.
With welding, you always have to worry about cracks if the part was heat treated.,
JR

+1

Another way would be a chain coupling. That means put another sprocket next to that one and wrap a short piece of double row chain around both sprockets, and connect your shaft to the second sprocket. This is commonly done to allow for minor misalignment where a cushioned coupler is too bulky or undesirable for other reasons.
 
....to a propshaft

Looks like you are putting a bike engine in a shaft drive minibuggy.

Drat, "propshaft" from a poster in Greece had me confused. I was thinking we were talking with Daedalus or Icarus....

:D

bolts & dowels with loctite sound good to me for one time low$$ assembly. If the bolts fail by fretting, Johns idea of the flex coupling is excellent. Works even better if it can be kept in a grease tite housing.

smt
 
Don't worry about getting it done until you know about and can exactly document the male spline. Everyone that can do it will need that information before they ever think about how much it will cost or if they can actually do it.

We've cut a lot of involute splines over the years without knowing anything about them :D Provided the customer has a good sample to go with, we can imitate it by grinding a flycutter and either mill with it or put it in the slotting attachment and slot cut with it. We'd sometimes have to cast a reverse image (using plaster of paris or body filler) to make grinding the tool a bit easier to gage.
 
There's probably a nut or bolt in the center holding the sprocket to the output shaft, as well as holding the endplay in the transmssion, which would have to be tightened when installing the sprocket/hub on the shaft. He'd have to have access to the nut/bolt, which makes attaching a shaft more difficult.
 
Last edited:
If you have a CAD file of the spline geometry, this is a 1 hour job for wire EDM. If you just have paramaters and need to develop the geometry it's 1 1/2 hour wire EDM job for someone with spline software. Either way, it's not that difficult.
 
Hi,
My friends do this everyday on their slotters. Every kind of serration and key way out there. As mentioned OD spec or sample would be needed.

Brian
 
Been running a homemade vehicle that uses a sprocket welding to a drive shaft, almost identical to what you are doing. Anyways it has held up now for a few years... Tig'ed with ER70S2...
 








 
Back
Top