Froment Engine Build Diary

This is a photo diary recording the build of a model of a Froment Engine built from a kit manufactured by the Old Model Company of Chichester, England. I intend to take my time with this project and, hopefully, at the end of it I will have an engine to be proud of.

26th August 2007

I ordered the kit via their website and it arrived safely two days later. Every thing was beautifully packed and there were no parts missing.

30th August

A handy template for marking out is included with the instructions and this was fixed to the base and the position of the various holes marked. The holes were then drilled and the base sanded and varnished.

Marking the base

2nd September

Once the varnish had fully hardened the two solenoid coils were fixed to the base and wired to a connecting strip on the underside.

Coils fixed to base

24th September

Progress again after being away on holiday! The break contacts and timing adjuster were assembled and then the completed unit was mounted on the chrome plated platform.

Contact breaker

6th October

The first job today was polishing a number of the turned brass components, thank goodness for my trusty tube of Simichrome. Simichrome by the way is the best metal polish that I have ever found. I was introduced to it by one of my steam toy collecting friends in the USA. Apparently it is very popular in the States with the biker community and I can recommend it highly. Itís not easy to get in Britain but I found it by searching on ebay.

Assembly of the all important bearings is made easier as the kit contains a slightly oversize axle, which is used to position the vertical bearing pillars. This ensures that the real axle, when fitted, will run freely.

Basic engine assembly

9th October

This morning the platform assembly was fixed to the base. The two brass terminals were also polished and fitted, now the engine is beginning to take shape!

Basic engine assembly

14th October

Nothing very photogenic today, I wired up the terminals, contact breakers and the coils. Not a particularly difficult job, but one that is made a great deal easier by the ingenious design of the box in which the kit is supplied. The box converts into an assembly jig that allows the engine to be securely held upside down. A spark quench diode is included in the electrical circuit. This suppresses any arcing that would otherwise occur at the contacts and prolongs their life.

17th October

The next item to consider is the flywheel, and whether it should be painted or left polished brass. I decided to go for a painted wheel with a polished brass rim. Brass does not take paint very well so the wheel was first primed with an etch primer specially formulated for the job.

Primed flywheel

24th October

Today was the turn of the interrupter assembly. The temporary, oversize, axle was removed and replaced by the real one. The drive pulley and the interrupter cam were also fitted. The interrupter contacts need to break the circuit each time one of the armatures, mounted on the flywheel, passes the magnets.

The photograph also shows the screw that is provided for fine adjustment of the interrupter contacts. This has been installed but will be set up once the engine has been fully assembled.


6th November

The flywheel was given its final coat of gloss black and allowed a week to thoroughly dry. When the paint was hard the brass rim was polished and the steel armatures were fitted.

Finished flywheel

7th November

Finished at last! The flywheel was mounted on the axle and the assembly of the engine was complete. All that now remains to do is any final adjustments to optimise the performance. I have thoroughly enjoyed this project and am very pleased with the finished result

Finished engine

Perhaps I ought to add a disclaimer that I have no connection whatsoever with the Old Model Company, the makers of this kit, other than as a highly satisfied customer. That said, I can highly recommend their model kits to anyone looking for an interesting and very enjoyable construction project.