Machining the smokebox saddle on a Myford lathe

This topic has 10 replies, 6 voices, and was last updated 3 March 2026 at 20:57 by Greensands.

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24 February 2026 at 14:37 #839180
Greensands
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@greensands
I have a job coming up to machine the smokebox saddle of a 3.5ins locomotive and am looking for photos or illustrations showing typical set-ups for machining both the radius and the side cheeks on a Myford lathe. It would appear that the two common approaches to the problem involve using either the faceplate or the vertical slide mounted onto the cross slide but there is nothing like a picture to show how it is done. A search through my collection of Martin Evans books has not proved successful. All ideas and suggestions most welcomed.
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24 February 2026 at 17:19 #839196
Brian Baker 2
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@brianbaker2
Greetings, with the smaller gauge locos such as you are building, I had quite a lot of success wrapping a sheet of course emery paper round the smoke box and using that to cut the radius on the saddle, plus a biggish curved file for the crusty bits. The sides I hand filed.

Hench the rush to buy a mill!

Try it, it might work.

regards

Brian B
24 February 2026 at 20:24 #839218
Rick Hann
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@rickhann79631
Is the smokebox saddle bronze or non-ferrous metal? If so, Brian’s method is very doable. When I built my Rob Roy several years back, I took a piece of wood and turned it into a cylinder of what I calculated to be the required radius, wrapped a piece of sandpaper around it and after a few minutes of sanding., the job was finished. No need for a complicated machining operation which would most likely need interrupted cuts which I do not like! No need to complicate your life. Regards, Rick
24 February 2026 at 21:07 #839221
Charles Lamont
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@charleslamont71117
I Googled for you. Here is a video: https://www.facebook.com/groups/714729802615009/posts/799517497469572/ and a photo:
24 February 2026 at 22:05 #839233
Greensands
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@greensands
Close inspection of the above photo indicates that the saddle casting has been soft soldered to a temporary base plate to enable it to be bolted through to the vertical slide, an arrangement which I think answers my question.
24 February 2026 at 22:32 #839235
Nigel Graham 2
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@nigelgraham2
I assume the abrasive techique means the casting is already close to size, but I would fear that cleaning every last grain of abrasive from the machine afterwards could be something of a challenge.

Looking at the photograph I wonder if the saddle casting, on its temporary base-plate, could be bolted to the cross-slide instead of the vertical slide, with a base of appropriate height. It would be a more rigid set-up.
25 February 2026 at 07:00 #839248
JasonB
Moderator
@jasonb
You don’t use any machines if just rubbing the part on abrasive wrapped round the smokebos so how will it get on your machines

I do feel that when most of the books and articles about machining parts like this they were mased on most home workshops only haveing a lathe. Now I don’t make Locos but I often have the need to machine a concave surface and my machine of choice is the MILL. Simple to then mill the ends.

Set a boring head to the required radius though a flycutter could also be used with a suitable cutter. Then hold your work vertically either in the vice or fixed to an angle plate and us eX axis to put on a Cut and Z axis to feed. Initial roughing cuts with the quill by hand final pass lowering the head or raising the knee.

Lathe method is really no different to boring a hole except you are only doing part of it. I prefer to set the work on the cross slide as it is mor erigid, using packing to get it to height. Then just use a between ctrs bar. If you slip your smokebox tube over the tailstock ctr before you start then easy to stop the lathe and test the fit. Edges can be done with a side cutting tool in the between ctrs bar or a flycutter.
25 February 2026 at 10:04 #839259
Greensands
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@greensands
With a job such as machining a smokebox saddle the main problem is finding the best way to hold the work piece to suit your own particular set up and not so much use of lathe or mill. If it becomes possible to soft solder/super glue the job to some sort of sacrificial support the problem becomes a lot easier to hold and therefore machine.
3 March 2026 at 20:41 #840091
Greensands
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@greensands
I have attached a couple of pics showing my final solution to machining the smokebox saddle after making a false start using the vertical slide mounted on the Myford. Depth of cut had to be limited to 5thou but I was quite happy with the end result.
3 March 2026 at 20:43 #840093
Greensands
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@greensands
3 March 2026 at 20:57 #840095
Greensands
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@greensands
The issue with using the vertical slide on the lathe turned out to be insufficient travel available on the cross slide for the required radius of cut owing to the space taken up by the vertical slide.
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