Flywheel Economics

[Brian Rupnow]

While building the Philip Duclos "Odds and Ends" engine, I have been researching flywheel costs. The flywheels finished size is 5" dia, x .875" thick. Two slices of mild steel (hotrolled) 5" dia. x 1" thick would cost $16 each. Two slices of 12L14 leaded steel the same size would be $36 each. Two slices of grey cast iron would be $30 each. I didn't even price brass, because although it is beautiful stuff to machine the price is way beyond my budget. Aluminum is too light to make good flywheels for this engine, so I didn't price it. Rough sandcast flywheels in the correct size range can be had for about $40 each, but due to the rather special configuration of the flywheel which holds the centrifugal governor weights, I don't think I can use the purchased flywheels, and again, at $40 each that stretches the budget. I have read about people buying small barbell weights and machining them to size, but that seems a bit Hokey, and they are said to be full of sand inclusions and gas bubbles anyways. My 10 x 18 BusyBee lathe will turn mild steel, but its not crazy about turning stuff in the 5" diameter range. I think I will go to a solid type flywheel on this engine, ---no spokes, no drilled holes, simply a dished area on each side and adequate slots for the governor arms and mechanism. I also think that I will paint the flywheels this time. (ignore the fact that the model shows the flywheels with drilled holes) ---any thoughts, suggestions, or commiserations?---Brian

 

[Jasonb]

Brian you could also consider making it up from plate. One disc in the middle that you cut the spokes out of and two rings either side to build up the rim.

I've just done it with a 10" flywheel so a 5" should be easy enough, and if you trepan out the rings you get to use the middle for something else. Only finished it last night so no photos yet but this is what I started with together with part done.

 

[mygrizzly1022]

Hi Brian
Could you find and adapt cast iron wheels from industrial castors? See link. A visit to a recycler may yield a suitable candidate.

Regards …..bert

http://www.grainger.com/Grainger/ecatalog/N-1z0dwvb

 

[rythmnbls]

Brian,

Have you considered a composite wheel, like this one ... [ame]http://www.youtube.com/watch?v=m_-iPpEuWRA[/ame] .

A five inch wheel could probably be made from aluminium bar stock with the iron/lead tires.

Regards.

Steve.

 

[Goldflash]

how about going to the car wreckers and getting some timing gears of belt driven overhead cam engines. They clean up nicely after machining of the belt teeth and its easy to insert a bush to get a fit for your crankshaft axles. Most are in the 4-6 inch diameter range

 

[Brian Rupnow]

Goldflash----Thats an interesting concept--

 

[Brian Rupnow]

This morning I found what may well be the perfect solution to my flywheel quest. Down at my local steel supplier I found a 7" length of mechanical tubing, 5" outside diameter x 3.5" inside diameter. They agreed to cut off two 1" slices for $27.00. This is the best price by far, and the good part is that I can build the centers from 1" aluminum flatbar. All of the detail work is in the central portion of the flywheels, so the only real machining on the steel rims will be a cleanup on the o.d. and i.d. and facing the sides to the finished dimension of .875". I will Loctite the steel rims to the aluminum centers. I know some cost will be incurred buying aluminum flatbar to make the centers from, but the ease with which the aluminum can be machined more than makes up for any added price differential. Also seen in the picture is a length of 1 1/2" x 1/2" hotrolled flatbar which will hopefully become the new crankshaft.

 

[Brian Rupnow]

This will be almost the last post on the "economy" of model flywheels. I went to see my metal supplier today, and picked up two 1" long discs of 6061 aluminum cut from a round length of 4" diameter.---For the admirable price of $10 total. That brings my total flywheel cost to $37.00, and lets me do all the complex machining on the aluminum centers, which is MUCH easier on my 10 x 18 Chinese lathe. I am happy with this price. I will post a picture of the finished flywheels when they are done.---Brian