# Minnie 1" Scale Traction Engine - 1 year into build!



## Inky Engines (Jan 14, 2015)

Its been a while since Inky Engines posted a new build.  After building a third of Elmer Verburg's 48 engines over 2 years I made the decision to try my hand at the 1" scale 'Minnie' traction engine as described by L C Mason.

Progress has been slow for a  number of reasons, not least the enormity of the project in comparison with most of Elmer's engines.  To date the engine has been built from sheet and bar stock with the exception of some of the shaft bearings that were machined from castings.

Unusually perhaps, I chose to start the build with a rear wheel spending many hours machining and fitting spokes and strakes!  I then progressed to the rear axle and its winding drum, final drive gear and brake drum. Hooked, then I built the second rear wheel!  Only then did I move on to the boiler (typically the starting point). With the boiler complete with the exception of the steam block and foundation ring (and pressure test!) I ran short of silver solder and propane - not wanting to find myself out of these essentials for the foundation ring I temporarily shifted my attention to connecting the boiler to the rear wheels!  This became the obsession, and because each shaft is marked off from its predecessor this involves machining and fitting not only the horn plates but all the remaining shafts, gears and bearings!

And that, with the exception of a little work on the fire hole door and the front end is the state of play at the end of the first year.

The build is largely typical of others previously described. I got hold of steel tube just right for the rear rims but didn't fancy cutting the internal recess - the rims were therefore machined with the outer recesses, cut in two and silver soldered back together with the outer recess now inside.  I form cut the gears from a combination of cast iron and mild steel, but used only 2 of the 6 involute gear cutters suggested to cover the range of gears in this project - the gears seem to run fine and a substantial cost saving is made.  Also of note are the internal keyways that Mason describes as a two part silver soldered unit that avoids having to plane or broach on the lath or otherwise - I also used the method with success on the flywheel.

I've attached a You Tube video with a compilation of still and video images showing the build - as always I would appreciate any comment or advice.

In conclusion I would like to thank all those who have previously built and shared this fine model.  In particular, I would thank 'my mentor' JasonB - I have never met or corresponded in any way with Jason, but his help and advice to others has proved invaluable. 

Kind regards

Geoff at Inky Engines


http://youtu.be/TslohHDgs3k


[ame]http://www.youtube.com/watch?v=TslohHDgs3k[/ame]








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## Herbiev (Jan 14, 2015)

A great video indeed. Looking forward to next instalment.


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## mikemott (Jan 15, 2015)

Geoff, I enjoyed your video , I have had the Minnie book by L Mason for 30 years at least, it is still one of those models on my bucket list.

Mike


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## pkastagehand (Jan 15, 2015)

Good start!  Nice work.  

I have the Rudy Kouhoupt book for his traction engine which is waiting till other projects are done.

Paul


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## Tomcat (Aug 25, 2015)

Hi,
Can you share some information on the type of silver solder you used, and on the stay bolt design? Great build so far! Looking forward to the next video.


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## Inky Engines (Aug 27, 2015)

Tomcat

Thanks for the interest.

I used Cupalloys 424 (24% silver - melting point 740/800 C) for the firebox, and 455 (55% silver - melting point 630/650 C) for just about everything else.

In terms of the stay design this one is the belt and braces version.  I used threaded bronze stay bolts and nuts, and then silver soldered them outside and inside - I had been unsure of my ability to silver solder the stays inside the firebox and decided to make provision for soft solder caulking the threaded stays if necessary.  As it was, with the aid of a cyclone burner for my Sievert blowtorch the stays were easily silver soldered inside the firebox.  Only 5 of the 9 stays each side are used to secure the horn plates, and these are of greater diameter to accept the horn plate bolts.  

I've attached a few images that may help - please let me know if you need any further explanation.

Kind regards 

Geoff at Inky Engines






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## Tomcat (Aug 27, 2015)

Thanks Geoff,
I started my build about 6 months ago and have just had to restart the boiler due to too many leaks after trying to fix one small one! Thanks for the tip on the silver solder (higher temp for the firebox). My stay design was very similar to yours and worked very well. I had to manufacture my own bronze bolts and nuts since I could not source any, but they came out great. New boiler nearly complete...
One more question regarding soft solder - is it permissible to use soft solder to fix leaks if the strength of the joint is already taken care of by the silver solder?
Last question - did you use spacers on the stays between the firebox and the wrapper?


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## Inky Engines (Aug 29, 2015)

Tomcat

Sounds familiar, I managed to scrap my first attempt at this boiler for similar reasons, fortunately at an early stage.  My solution was more heat (Sievert 2942 burner or cyclone as appropriate) and insulation of the areas where heat was not required with vermiculite board. 

I turned bronze stays, but used commercial brass nuts inside the firebox.

You ask if it is permissible to use soft solder to seal leaks if the structural strength of the joint is taken care of by silver soldering.  I think the stock answer is talk to your boiler inspector!  Personally, I don't have ready access to a boiler inspector and do not intend to have the boiler examined - my intention is to build, hopefully run in the workshop and then paint, polish and display the model.  I have of course tested the boiler at pressure, with no evidence of leaks or deformation at 120 psi.  As a last resort I seen no reason why you should not caulk with soft solder, L C Mason envisaged that all the threaded stays would be soft, not silver soldered. You would of course not be able to do any subsequent silver soldering on the boiler. 

There is no need to fit spacers between the firebox and wrapper.  It is however useful to slip rings of silver solder around the stay between the firebox and wrapper - for this reason I fitted the stays before completing the foundation ring.

Good luck with the rest of your build.  Should you wish to discuss anything further please do not hesitate to send me a personal message, but bear in mind there are others on this forum who have far more experience than I of building this traction engine.

Kind regards

Geoff at Inky Engines


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## gus (Aug 29, 2015)

Would love to see this tractor engine running.


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## Tomcat (Sep 24, 2015)

Hello Geoff,
Just to let you know that I have completed my boiler and pressure tested it successfully! Thanks for the tip on the solder types - this helped a LOT! I made my boiler stays out of bronze as a 4mm thread (5mm long), with a 1.3mm thick, 6mm diameter flange, then continued with a 12mm long 4mm threaded part to go through the wrapper and firebox. On the inside I used brass nuts, and the outside used the flange. In this way, I had no chance of water leaking out through the threads (at least on the outside).
I can now continue with the back wheels and rear end (front section was completed some time ago). Will post some pictures at a later date.

Regards Tomcat.


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