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Splined Bore (Novice Question)

Captain_Chaos

Plastic
Joined
Dec 5, 2006
Location
Philadelphia
I'm much more a mechanic than a machinist, but I'm interested in making custom aluminum shift levers for motorcycles. I've figured out how to do all of it except for machining a bore that will match the splined shaft coming out of the transmission.

Anyone here know how to do this?
 
<Where would I get one to match the spec that I need? >

Industrial supply houses like MSC, McMaster-Carr are a good place to start. Check out their online catalogs.
 
I got some prices a while back for spline broaches for a similar application. The cutter for a rotary broach was about $600 each, and the push thru broach was close to $1000. I figured out another way to make the internal spline with good results and minimal time (about 30 seconds), but its not a process I'm willing to share with anyone.
 
You are not likely to find a splined broach for a low price in a catalog of standard tools, or from a custom grinder. You can get comparatively low-priced hex and square broaches from places like MSC. Keyway broaches in inch and metric sizes are similarly easy to get and not very expensive.

So one approach would be to get a cheap part with the correct splined hole and cut away all but the area surrounding the splined hole. Then insert that splined hole adapter into your lever. You could do that in several ways. For instance, you could mill the O. D. of the splined part to a hex shape and hex broach your lever hole.

Another possibility is to measure your spline and see if one spline groove in your lever bore could be made with a keyway broach. That will be true of square splines, but will not work with involute splines. Then devise a way to index the broach so that all the splines can be done, one at a time.

Larry
 
I have on occasion needed to do the same for a square-cut multi-spline.
How I did it:

I first started with a standard broach bushing. I was lucky for my particular need as the single broach I used was of standard width and size.
Next, I took the bushing, stuck it in my index and sawcut on the mill 1 more slot in the position of the next spline.

After this was done, I inserted the bushing into my workpiece and using the broach cut the first slot.
I then turned the bushing until the second slot lined up with the one I cut and inserted a key and went on to broach the next slot with the broach in the first slot of the bushing. Each time one is cut, rotate the bushing for the next cut and have a key in the last one you cut.

Now, If you cannot find a standard broach and bushing to fit exactly what you need. MAKE ONE.
Start with a billit and cut it to what size on a lathe.
If your spline is metric or of non standard broach width, simply put it on your surface grinder and finish grind to correct width or, take it to a mill shop and let them grind to width.
Next with your new billited bushing, set it up in your mill, or who's ever mill, index and saw cut to proper width. Cut the first slot, index and cut the second slot.

There you go.


This method may take a few extra minutes but it it will not be near as costly as a multi splined broach and bushing you would need buy. Let alone the size of the arbor or press to work one.

I've got pretty good doing it this way.

Patch
 
Maybe you could make your own broach since your punching aluminum (the softer the better). If the male splined part is a decent grade steel (or you can get one made in a steel that can be heat treated), grind stepped rings around the OD to make the broaching teeth. Use it in a press. Or course, there's details in this (make sure your broach is long enough to go through the female, it will a tight final fit, etc.) but it's a possibility.
 
hey Lca078,

I wondered about the approach you're suggesting. The only drawback is that I'd have to ruin an antique shaft to make it happen. I'm going to see if I can get a Tai repro. Thanks
 
Might want to see if MSC, McMaster or others sell the same style splined shaft as stock. Sometimes it's readily available and you can make decent broaches.

Making homemade taps, dies, broaches, etc. is a highly effective but hardly used approach for one-off or low-volume pieces. For instance, the other day, I had to tap 1-1/8 5tpi acme left hand in a 3" brass rod to make a backlash nut. Instead of buying a tap, I was going to just make a tap out of a piece of the hardened all-thread acme rod the nut would fit on, ensuring a tight but effective fit. In the end, I didn't do it because I happen to run across a cost effective source for the nut. But I've seen similiar taps made with grade 8 bolts for emergency tapping aluminum plates. Just as long as the material your tapping, broaching, etc. is much softer than your home-made tap, broach, etc., you should be fine.
 
If your lathe is equipped with a spindle lock, and you have a degree wheel to index the part, you can cut the splines using the carriage travel to push a suitably shaped cutting tool through the hole. It's a tedious process, but doable. Using a mill or drill press and rotary table to lay out the pattern, and then drilling out most of the material will speed up the final op on the lathe.

Some people have shown pics of lever-operated keyway broaches for use on their lathes. You might try searching for that, too.

Roger
 
here is me single pointing them by abusing my quill as an arbor press. (brake locked on)

grind up a crude cutter (I ground most of the head off of a bolt) and use a rotary table or indexer to turn the part and stroke-turn-stroke-turn-stroke-turn... your heart out. you can index out after each full revolution if you cant take the full depth in one shot.

broaching.jpg
 
If you're not going to share information, why did you post?
First, because I ain't the damn Red Cross or the Welfare Office, and I don't owe you a friggin thing.

Second, I told you the price on 2 commonly available types of broaches, and for anyone with no creativity or knowledge, either of those will get you to making splined holes right away. All it takes is money.

You'll find, if you participate here for a while, that most anyone here who makes a living in the machining business has processes and procedures they wouldn't share with their best friend, because those are the things that help them maintain their competitive edge and continue to put food on the table.

Any more questions Dickhead? If so, ask someone else because I have nothing further to share with you or any other know-nothing with an attitude like yours.
 
That's a little harsh there metlmunchr. It does seem a little perverse to say you've got a process that you won't share. If you've got proprietary processes then keep 'em under your hat. Don't go teasing folks with them. You're right that you don't owe him anything, but why bring it up if you aren't going to share?

-Justin
 
What's perverse about it Justin? The information would be useless to anyone who doesn't know how splines are normally cut, but probably somewhat useful to more than a few of our Asian friends who monitor this board regularly.

Putting on my "Don hat" now, and telling it like it is with no regard to who I may offend, one of the problems on this board, and most others, is failure to read EXACTLY what was asked, combined with questions that don't ask what the poster really wants to know. Case in point...."interested in making custom aluminum shift leverS". Note the plural form of lever, implying the person wants to make multiples of the product. Now, go back and read every post in this thread and tell me exactly how many replies have the remotest applicability to production parts. As the thread progresses, it becomes obvious the poster wasn't interested in how do this on a production basis anyway. What he wants is the $1.98 solution, so the posts that would appear to not address the original question, do in fact address the real question he was asking. If he had clearly stated what information he was really looking for, I wouldn't have wasted time posting anything at all. What I did post was the most direct response so far to the question he asked. Specifically, the 2 most common types of tooling used for low to medium volume spline broaching, along with fairly current cost estimates for each type tooling in the size range needed.

Unfortunately, I don't have a compendium of politically correct responses to use when I give a direct and correct response to a question and get some smart-assed remark in return. So, lacking these social skills, I find it simpler to just take whatever insult they want to spout off, raise it to about the 5th power, and send it right back to them. If you can't take it, then its best to not pass it out in the first place.
 
To metlchr;

First, I totaly agree with you that most of the posters to a thread do not understand or have not really read the question of the first post. Many times the answer is not relavant to the question asked.

Second, I think you are reading into this post an alterior motive that is not there. He plainly stated that he wanted to do many of them, not one. He also said he is a mechanic not a machinist. Many machinists don't know how to cut a spline and don't need to depending on their job requirements.

Third, I have heard people say they have discoverd a way to do something and will not share it. My response is I don't believe them and I really don't care if they do have a way or not. It is foolish, arrogant, and arguementive to make a statement like that. If you know a personal trade secret then keep it to yourself. I think we all have secret ways to do things we don't share.

Lastly, I don't know you and from your smart aleck attitude I don't want to know you.
 








 
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