Assembly alignment problem

12bolts

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I am making a muller for my casting sand. I am trying to use a rear axle for the drive mechanism. I sourced a solid axle housing from a RWD car and cut the outer ends off the housing, (discarding the center), leaving them about 200 mm long each. I plan on welding them together to make a short solid tube with a wheel bearing in each end to support the shortened axles. I cut 1 axle close to the outer bearing, leaving a short stub to weld a female spline to. The other ½ axle, (not yet cut) I planned on cutting similarly and then welding a male spline to it. This will then give me the ability to assemble the two ½ axles easily.
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I wanted to use the spline connection to provide some ridgidity to the axle connection as there is no longer any centre bearings for support. I think a flexible drive coupling will allow the axles to move too much laterally within the housing. The assembly runs vertically inside a drum with the (now) lower axle flange having the drive connected to it, and the (now) upper flange carrying the mulling assembly.
In use the axle will rotate at a speed in the range of 10-20 RPM so I am not (too) concerned about marginal errors of alignment, but obviously I would like to get it as good as can be.
I mounted the shortened axle in my lathe and running true but I am having trouble getting the female spline positioned concentric and co-axial to weld it on. I also forsee this being a problem when it comes to shorten the other axle. So looking for suggestions/ideas.
This is (not mine) a muller in action. This one uses a rotating drum rather than a rotating muller mechanism, but the theory is the same.

Cheers Phil
 
For the male spline I would drill and ream each piece for a dowel pin. You are most likely going to have to straighten them after welding. For the female spline I would bore the splines out about an inch and turn the axel to a press fit. And then weld.
 
I am making a muller for my casting sand. I am trying to use a rear axle for the drive mechanism. I sourced a solid axle housing from a RWD car and cut the outer ends off the housing, (discarding the center), leaving them about 200 mm long each. I plan on welding them together to make a short solid tube with a wheel bearing in each end to support the shortened axles. I cut 1 axle close to the outer bearing, leaving a short stub to weld a female spline to. The other ½ axle, (not yet cut) I planned on cutting similarly and then welding a male spline to it. This will then give me the ability to assemble the two ½ axles easily.
In use the axle will rotate at a speed in the range of 10-20 RPM so I am not (too) concerned about marginal errors of alignment, but obviously I would like to get it as good as can be.
If it were my task, I'd whittle one shaft to a taper, and bore a cone in the other, instead of using a spline.
Then, with the axle fitted together, maybe use the lathe to make the tube whole, either by welding on flanges
and turning the flanges with the axle as mandrel, or maybe by just making a good outer cylinder fit
to a collar (press both housing stubs into a coupling collar, and weld that).

Instead of taking up loose axial play in a spline, that'd be the collar sliding before weldup.
 
I wish you had asked for design concepts rather than how to achieve the one described.
Obviously, I don't know all your constraints but, the described concept strikes me as unnecessarily troublesome.

Is there an advantage of having two short axles joined by splines vs one longer shaft?

Would one of the stock (not shortened) axles be long enough (it can always be shortened) to pass through your intended axle housing assembly?

What drive system do you intend (chain, V belt, flat belt, gear, other)?
 
Perhaps I'm missing something but it seems to me that the rollers have to spin in opposite directions.
Looking at other units, they seem to have offset shafts each with their own bearings.
 
I take it the OP is turning the tub not the rollers.
 
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