Wooden Gears

My son is building a wooden traction engine. I have already warned him of the difficulties of raising steam in a pine boiler but he is pursuing the project and as he is a glutton for punishment wishes to make a full gear chain in wood. What sort of wood would the forum advise that he uses?

Mick

Ironwood

Watermills and windmills used fruitwood such as apple for gear teeth, although this was running against cast iron. This website has a list of the properties of different timbers for making wooden clock gears, so it might be relevant.

Brian G

Hornbeam was what they used for the inserted teeth in things like water wheels. **LINK**

https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/british-trees/a-z-of-british-trees/hornbeam/

He might also find this interesting : **LINK**

https://quillandpad.com/2019/02/16/rick-hale-wooden-clocks-designed-and-built-as-if-by-john-harrison-except-today-and-in-the-usa-beautiful-photos-video/

MichaelG.

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Oops ... no conflict intended Brian [our posts crossed in the æther]

Edited By Michael Gilligan on 14/06/2020 14:12:38

It all depends on whether it will just be a static model or one when pushed the gears will turn or even to the point of running it on air.

For a static model, any close-grained wood will do.

Woods that would be suitable for moving gears I would suggest Lignum Vitae very close grain and takes detail well, beech is another that is suitable, also a cabinet grade plywood as that will give strength in all directions.

Those that make wooden clocks tend to go the plywood route.

Lignum vitae is hard to come by and I can't remember if it is now on cites list. If the gears are small and you want the LV wood then look for old Bowls balls before they started using composite materials.

I was very fortunate in that I was able to get 18 LV balls and I know they are not cheap to buy. Also worth noting is that LV was used as bearing material because of its oily nature which can also be a downfall if you want to glue anything to it a wipe over with thinners and glueing immediately seems to work.

I forgot boxwood which in woodturning circles takes a screw thread very well

Edited By Derek Lane on 14/06/2020 14:17:19

Just as an alternative - one can get ‘wood’ filament for 3-D printers. I don’t know how realistic it might look.🙂. Some have wood fibres rather than powder.

For different toys I have made for young relatives I cut the gears from good quality aircraft 5 ply plywood. This effectively solved the grain issue with the gears, which were very lightly loaded. The glue used in the plywood was very good, no delamination during cutting or in use occurred. Just food for thought.

Although a wooden boiler would be difficult for steam it might be possible for say CO2.
Don't forget some unlikely materials have been used in the past like granite for Cornish tin mine engines.

Another vote for Hornbeam and Fruit woods. Lignum Vitae would be a good choice, although a little expensive and not that easy to get hold of except as Woodturning blanks. The "self lubricating" properties of LV could be useful, but as a consequence, make it difficult to glue.

Interesting project, keep us posted on progress.

I'm with Jeff on a good quality birch ply, no problem with short grain causing half the teeth to break off or the gear going oval if its not well seasoned when brought inside a Centrally heated enviroment

oak was also used a a bearing along with a dolop of tallow........

pretty sure LV is a restricted wood now.......

A poor relation is Almond wood......very heavy and quite hard, def dence........

Lucky for me it grows wild on my plot.......biggest trunk I've found was 4-6"......

In his delightful book, The Village Carpenter, Walter Rose describes the process of re-cogging a mill wheel for which "hard dry beech" was used. The wooden cogs ran against cast iron gear teeth and the mesh of the finished job was checked by ear.

PS Palo Santo is similar to LV.

Edited By ega on 14/06/2020 16:27:31

Agree in spades. No natural wood of any species can have strong teeth on all four points of the compass. If the teeth at 12 o'clock are parallel with the grain, those at 3 o'clock will be perpendicular to it.

For a really well engineered wooden gear, maybe plies at 30 or 45 degree increments made from birch veneer would provide a good solution. Epoxy resin to glue the plies and a good squeeze in a cider press while it is curing.

Presumably he knows of Mattius Wandel and the woodgears.ca site.

Edited By DC31k on 14/06/2020 16:26:33

Wow great project! Well when he returns to school see the Design Technology technician; most likely the school should have a laser cutter or possibly cnc router... if so explain your project and take a drawing to get them interested! As laser cutter will cut lite ply to 5mm , if you draw your gears ( search the web for a gear catalogue) and use their line cad drawing of suitable gear( thanks Jason))... it should be possible to enlarge or reduce the dxf drawing on school Techsoft software or the laser cam software : then laminate together after cutting and preferably do the central bore for the shafts to the centre and perhaps a small hole offset for a dowel pin so that the gears sandwich together and teeth arrange in rows! Which helps on assembly

The whole gear assembly could be given a coat of cellulose dope to toughen the fibres!

No need for lignum or hornbeam ( I have used it; too hard to work) and feel it would be to hard to use for a young person unless supervised and access to equipment.

Incidentally I have seen 3d printed gears which may work... but think wood best. Same for Flywheel!

It depends upon what scale the model is being made at? But the thread suggestion above is possible ie air running! Or electric motor...

Great Project.

Regards

vic

Purpleheart is quite attractive and close-grained.

But the missus thinks it smells of sick...

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True ...That’s why I referenced inserted teeth

MichaelG.

I guess it depends upon what size / scale it will be ? If its a model, I would go for Beech Jabroc - after all it is wood.

Will he paint it or rentokill it ?

I knew a chap who built a wooden engine, it wooden go.

Mike

Robbibs Timber supply marine ply to BS standards from 1.5 mm up. 5 mm up is available in five or more ply. Varnishing with epoxy resin should give good strength. They can supply full sheets or cut to size. I've had excellent service including delivery to France.

Russell

I agree that birch ply is probably the best choice. However, if the look is not acceptable then Pear is pretty isotropic, has no obvious grain and machines well with engineering tools. This will be the bridge of my Baroque guitar, the slot was milled with a 4mm 4 flute cutter.

This is one of the "Moustaches" that will be glued to the soundboard on the ends of the bridge. This is also in Pear but has been dyed black. Cut on the CNC mill with a 1mm 2 flute carbide endmill.

HTH,

Rod