Threaded Woodruff key

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pbiYoung

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I need to build a replacement axle for this amusement park train ride, and it’s pretty straightforward, except for the method which was used to key the wheel to the axle.
I have a couple of ideas on how to pull this off, but wondering if anyone here has done this before ? or has similar experience and thoughts on how to achieve this.

The issue lies in, utilizing the existing tapped hole, or more specifically (half of a tapped hole), in the existing train wheel. I need to construct a new axle so that the end of the shaft has half of a tapped hole to line up with the other (existing) half in the wheel and be able to insert a 6 mm set screw to lock it in place.
 

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pbiYoung said:
I need to build a replacement axle for this amusement park train ride, and it’s pretty straightforward, except for the method which was used to key the wheel to the axle.
I have a couple of ideas on how to pull this off, but wondering if anyone here has done this before ? or has similar experience and thoughts on how to achieve this.

The issue lies in, utilizing the existing tapped hole, or more specifically (half of a tapped hole), in the existing train wheel. I need to construct a new axle so that the end of the shaft has half of a tapped hole to line up with the other (existing) half in the wheel and be able to insert a 6 mm set screw to lock it in place.
Click to expand...
The drill and tap keyway is something you do in field repair.

Dave
 
pbiYoung said:
I need to build a replacement axle for this amusement park train ride, and it’s pretty straightforward, except for the method which was used to key the wheel to the axle.
I have a couple of ideas on how to pull this off, but wondering if anyone here has done this before ? or has similar experience and thoughts on how to achieve this.

The issue lies in, utilizing the existing tapped hole, or more specifically (half of a tapped hole), in the existing train wheel. I need to construct a new axle so that the end of the shaft has half of a tapped hole to line up with the other (existing) half in the wheel and be able to insert a 6 mm set screw to lock it in place.
Click to expand...
Note for keyway it depends on the equipment and tooling you have.
You can weld and machine a flange and bolt to wheel.
So what do have ?

Dave
 
I have done this... I had to machine a new gear for a Hendey lathe...

20200904_144836.jpg

The gear on the left has a square key and a threaded key. I machined the gear, then had to re-establish both keys. It isn't too difficult IF the existing threaded hole is centered directly on the joint. (Mine wasn't).

I would machine a 'collar' to fit around your axle... just a sacrificial piece that presses on the axle, flush with the end. Locate the joint line and drill and tap the axle and collar together, then remove the collar and discard it. Line up the half hole in the wheel with the half hole in the axle and install the wheel.

The trick is to have enough tolerance on the axial positioning of the wheel to be able to carefully line up the threads on the two half-holes...

I hope that makes sense...

-Bear
 
Make the axle.
Make a sleeve for the axle out of the same material.
Fit the sleeve on the axle.
Drill a hole on the seam.
Tap the hole.
Remove the sleeve.
Hope it lines up enough with the old hole.
Chase tap the axle and hole together.
 
Just start at a new location and drill & tap both parts at once. Fill the old threaded hole with liquid steel - epoxy. Way easier. Or if you really think it needs to be filled with steel, drill it out and stick a dowel of steel in with Loctite.
 
Why does it have to be threaded. Is there a particular reason you can't just use a round pin?
 
th62 said:
Why does it have to be threaded. Is there a particular reason you can't just use a round pin?
Click to expand...
A threaded key serves two functions... it acts as a conventional key to prevent the wheel from turning on the axle, and also keeps the wheel from walking off the end of the axle. The threads keep it from moving axially...

-Bear
 
Nothing a central threaded hole in the middle of the axle over come. I've never used a threaded key, but I'd imagine trying to line up the axle thread with the wheel thread would be pain.
 
th62 said:
Nothing a central threaded hole in the middle of the axle over come. I've never used a threaded key, but I'd imagine trying to line up the axle thread with the wheel thread would be pain.
Click to expand...
It some you typically do in field or lacking the equipment to a keyway.
The problem is replacing a part you fill the old keyway with weld and re-drill for tap hole.
I have use this type when in field using a alen set screw.

Dave
 
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