Thank's for the interest Geoff, not sure how many issues it will get spread over but maybe 8-9 if Martin continues to give it 3 pages per issue, there are 15 drawings and two are in the first instalment but there is not so much text associated with those parts

Yes the pedestals are a bit easier to make that way and I also left them square sided rather than having to turn them, though with the basic mechanicals set out on my drawings the model could be embelished if the builder wanted.

Yes 1/32" = 1mm as it's a more manageable size and more beginners are likely to be brought up with the metric system and using metric tools and machines. It could also be enlarged working at 1mm=1/16" or reduced back to the original.

J

There will be a link in the installment with the flywheel but this e-bay seller usually has them but sods law he does not have one listed at the moment. He used to do the casting for College Engineering before they changed hands.

For display when the engine is not running under any load you don't need much pressure and if it has been made well with minimum friction will not require much force to turn it over.

As soon as you put a load onto it you will need up up the pressure as you can't get effort out if you don't put effort in.

As this is his "simple" design it is a lot easier to make a crank with just one web on the end of the shaft and a pin into that than would be needed if say the cylinder were set centrally between the columns. On the full size it probably kept the costs down and made erection on site a lot easier.

If I write up a few more of the similar sized Series 24mm bore engines than construction will become a little more complicated with each as cylinders become fabricated and the cranks sit between bearings. And maybe move on to ones that need more exacting fits such as hot air and IC engines.

Edited By JasonB on 30/07/2019 19:02:49

You might be a bit tight on the Y-axis as it is 115mm OD but if starting with a circular blank about 100mm on the Y-axis may be enough using a 6mm cutter.

I suppose the spokes could be cut from plate and set into a rim in which case assuming you start with a turned disc then with a 6mm dia cutter you would only need 90mm movement.

A Minnie flywheel would be about the same size though does not have the curved spokes which are quite nice.

Another option may be to set up the blank so it can be indexed 6 times and just run code so that it cuts one spoke and half of each space either side, then index around an run the code again.

I'll sort you out the STEP file tomorrow if you want to play with the CAM

Will explain it later if what I said in the article was not clear but the engine was made before I had the CNC.

Edited By JasonB on 31/07/2019 07:14:31

Looking at the drawing at the bottom left of the base is a dimension of 22mm in from the edge to the ctr of the internal corner radius which I have marked in red which gives a distance from the cylinder Ctr datum point of 28mm (half base width less 22mm) in the X-axis and zero in the Y-axis. As the front edge of the base is 4mm from this point an 8mm cutter can be used as per the text.

First thing to do is set the rotary table up on the mill with it's axis directly below that of the mill and zero your handwheel dials or DRO. Then turn the table until the scale reads zero and clamp the work to the table with some packing between and make sure it is square to the lathes axis and the ctr of the cylinder is lined up to the mill spindle.

Pop an 8mm cutter in your holder of choice, lock the Y-axis at zero and then cut in from each edge to 28mm from the cylinder ctr. Assuming a bench top mill then something like 1mm deep per pass will do or more if you have sawn away most of the waste before milling. You should then end up with two slots like this.

Reposition the clamps to the sides and you can now also lock the X axis at -28, 0 and bring the cutter back down to take your first cut around the curve which will start from zero degrees and end at 180deg, repeat this until you have cut ring through and hopefully have a shape like this. before rushing to admire your work run the decorative moulding around the curve and front edges while the work is correctly located.