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Wheel out of true

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Paul M09/07/2020 15:43:25
44 forum posts

I am building a 31/2" Lifford Hall loco. I fear I have somehow managed to get one of the driving wheels running out of true. I machined the axles between centres and used loctite to secure the wheel. There now appears to be about 14thou sideways (lateral) movement on wheel at the outer edge. The tread is concentric to the axle. I fear I may have not gone through square with the reamer as I did suspect a bit of lateral movement before loctiting but assumed it was the clearance between the wheel and axle prior to fixing.

What puzzles me is that I used a jig set in lathe to machine each wheel.

I really don't want to start another wheel so am looking for suggestions/advice on the way forward. My initial thought was to drill out the axle and somehow set the wheel up and bore out a few thou remake the axle and hope.

Things were going well up to this point!!

JasonB09/07/2020 16:10:23
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19166 forum posts
2105 photos
1 articles

For an accurate fit I always prefer to bore as you can size the hole to whatever needs to fit with a loctite joint having a smaller hole than say one in a bearing.

Drilling then reaming particularly into a casting is also prone to problems as any hard spots, voids, etc in the casting will cause the drill to wander and then the reamer will just follow the path of the drilled hole.

You could possibly bore out the wheel and loctite in a piece of bar and then bore that out to fit your existing axle.

Paul M09/07/2020 16:15:11
44 forum posts

I appreciate your advice. I have realised too late the possible problems with drilling and reaming especially into cast iron.

Phil H109/07/2020 17:07:46
317 forum posts
32 photos

Paul,

Unfortunately, It feels like deja vu. I had almost exactly the same snag with one of my Rob Roy wheels. I ended up cutting the axle and reboring on a face plate. I also had to make a wheel quartering fixture because I fouled up the quartering on the lathe.

As Jason has explained, I suspect reamers can sometimes follow the drill and produce a wobble on locomotive wheels and other similar parts.

Phil Hwheel rebore - copy.jpg

Baz09/07/2020 17:22:44
494 forum posts

A reamer will always follow a drilled hole, best way for things that matter is to drill, bore and then ream.

Steve Richardson 221/10/2020 11:28:39
14 forum posts
1 photos

you do see many people on youtube videos drilling and reaming to size, but as said, you are best drilling under size then boring

J Hancock21/10/2020 12:43:27
480 forum posts

Worst case is +0'010" dia on new axle and bore wheel to suit.

Mick Henshall21/10/2020 13:42:31
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541 forum posts
34 photos

Gentle heat applied the axle wheel hub should release the loctite so you can pull wheel off

Mick 🇫🇴

Howard Lewis21/10/2020 14:28:52
3807 forum posts
3 photos

I would feel tempted to recover the situation by boring out the wheel, and Loctite in a bushing which can then be bored to correct size for the axle.

If you start making things to odd sizes, you will end up like an ex LPTB bus, with almost every part to some non standard size. Reassembly, after a strip will be a nightmare to mate the correct parts together.

Howard

duncan webster21/10/2020 17:09:02
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2858 forum posts
32 photos

This is model engineering, things are made to fit each other, how many times do you take the wheel off its axle? Number stamps keep track of which bit goes where.

old mart21/10/2020 18:36:28
2245 forum posts
165 photos

Boring out and bushing, as Howard says, will be the best solution. The only drilled holes I would trust would require a solid carbide drill.

Nigel McBurney 121/10/2020 19:09:27
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763 forum posts
3 photos

Looking at the photo of a wheel on a myford faceplate,my method is to rough machine the wheel,and leave the width of the flange oversize , then grip the wheel flange with soft jaws in the 3 jaw chuck,then machine to size the wheel tread ,the inner side of the flange ,face off the front of the wheel rim and boss and then drill,bore, and ream the axle hole,only leave about 5 thou on diameter for reaming, I know that leaving small amounts to be removed by reaming is supposed to cause the reamer to rub and wear,but I have found that it produces good results,and only a few holes are being machined,its not production .Better to loose a reamer than expensive wheel castings. the wheel can then have the back faced off and the rad on the outer rim machined ,the important bit of this method is that the the critcal machining is done at one setting,with good concentricity and no wobble.

not done it yet21/10/2020 19:29:01
5154 forum posts
20 photos

I’ve never checked for straightness afterwards, but if I want to avoid a wandering drill, I drill a pilot first then finish to size with an end mill.

Any comments on how much better than just using an ordinary drill? Or less good than boring. Only relevant for smaller holes, of course.

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