3" allchin trunk guide casting

Hi there, I know this is a long shot, but I've taken over the building of a 3" allchin traction engine, I've hit a big obstacle though where as the chap who built the engine machined the trunk guide out of square, where as the valve spindle isn't square to the wayshaft for the valve gear. I just wondered if anyone would know where I could get hold of another trunk guide casting, or someone who may be 'sitting' on one. I have been in contact with John Rex, who supplies castings for the engine, but only a split casting (valve spindle guide bracket bolted on the side) where said much prefer a single piece one for strength and looks. I've taken the project on due to ill health of the original builder and am frantically looking to get the engine running before he passes on, therefore I'm asking everyone who may be able to give me a glimmer of hope as to finding one. Thank you reading this and I hope you may be able to help.

How out of square is the valve guide? could you not bore it out true and fit a sleeve or plug it and bore afresh?

Whats your one made from iron or GM? if GM was it a one piece or has the bracket been silver soldered on like the 1.5" but out of square.

Hi, yes that's not a problem with the valve guide, but I haven't got the material to do that with the wayshaft, it's almost a whole hole out (roughly) so it's right on the edge of the casting at one end, but central the other! It is possible, just it would be soo much easier if I had a clean slate so to say!!!

No, it's a single piece casting, done in cast iron, defiantly not GM.

Thanks

Hi, yes that's not a problem with the valve guide, but I haven't got the material to do that with the wayshaft, it's almost a whole hole out (roughly) so it's right on the edge of the casting at one end, but central the other! It is possible, just it would be soo much easier if I had a clean slate so to say!!!

No, it's a single piece casting, done in cast iron, defiantly not GM.

Thanks

Aaron,

I think you will find that John Rex Model Engineers on 01977 699669 or [email protected] produce the drawings and castings for the 3" Alchin.

Hope this information is of use.

Trevor.

Hi Aaron

I am also building a 3" scale Allchin, I very much doubt you will get a one piece casting, the 2 are riveted or silver soldered together.

A friend is also building a 3" scale and waited several months for castings, I fabricated both from solid.

If I understand you correctly, everything is OK apart from the bore for the slide valve spindle not being square to the weigh shaft spindle bore, in which case could you silver solder a plug into the bore and re-machine?

Is the bore for the weigh shaft spindle square to the trunk guide?

Nigel

Edited By tractionengine42 on 19/01/2014 07:34:15

Hi Nigel,

No, the wayshaft spindle bore is out against the trunk guide too! What they've done to try and compromise is turn the casting slightly on the face of the cylinder to make the wayshaft run level, but it's also out on the other axis. Therefore when they rotated it round, it put the valve spindle off centre in the casting and the holes in the bolting flange at the front which all need to be moved if I were to repair the old one.

Hi Aaron

Not straight forward then.

Perhaps the bracket that houses the weigh shaft and slide valve spindle was out of alignment when attached to the truck guide. Maybe it's possible that the bracket can be detached from the trunk guide then re aligned/rotated and re-attached using a jig to hold the parts correctly, a tricky job I know.

My friend made a jig to align the parts and silver soldered them together, I also made a jig and riveted mine.

Nigel

Edit- just re-read you post and realised that what I said won't work, with the weigh shaft levelled the slide valve spindle will be out of alignment. So the relationship between the weigh shaft spindle and the slide valve spindle that's in correct, when either one is correctly aligned relative to the trunk guide etc. then the other will be out of alignment.

At the moment, other than removing some sections and silver soldering on new sections to re-machine I am not sure what you can do to rectify. Unless new castings are ex-stock you can expect to wait along time for delivery.

Nigel

Edited By tractionengine42 on 19/01/2014 10:33:38

Given that John Rex's castings are two part and the likelyhood of finding someone who wants to part with a one piece if any others exist is slim you really only have a few options

1-Fabricate from steel with a silver soldered bracket

2-Cut off the bracket from your iron casting and bolt on a new fabricated one

3-Machine from iron bar with a bolted on fabricated steel bracket

4- Use the two piece casting from JR

5- Make a pattern and have a one piece cast

I'd probably go with option 3 and hide the bolts and fillet the joints with JB Weld

Hi Nigel,

Yes that's correct, when the valve spindles lined up with the relative hole in the block, the wayshafts out, but the wayshaft is also not square to the main bore of the trunk guide, if you understand what I mean.

Thanks jason, I was actually looking at getting another one cast from the old one, coating it in wax or car body filler to allow for shrinkage and making my own cores etc. a lot if work I know, but it doesn't look like I'm going to find another!! Will probably get 5 or 6 done, for anyone else who wants one or just in case of a blow hole etc.