Engines > From Kits/Castings
Mery Explosive Engine
Chipmaster:
I saw a part built Mery Explosive model engine at a Model Engineer Exhibition possibly 20 years ago then more recently YouTube videos of completed engines running. The way the engines ran fascinated me so when a set of castings were for sale on eBay UK a couple of months ago I read all of the build articles I could find on the internet and took the plunge despite knowing there would be difficulties carrying out some aspects of the machining with my machine tools.
Here is the set of castings.
The set of castings. by Andy, on Flickr
My first consideration was the 150 and 50 tooth gears. I reckoned it would be advisable to determine the position of the crank and countershafts after I had the two gears meshed together. I have no experience of cutting gears, the B&S type dividing head that was given to me is a bit doubtful and I would have to buy the appropriate gear cutters. Fortunately a local firm Redditch Gears quoted a reasonable price to cut the 150 teeth on the pre machined to 4.75" diameter iron casting and I was able to buy a 50 tooth 32 diametrical pitch, 20 degree pressure angle steel gear off the shelf from HPC Gears. Therefore Redditch Gears cut the 150 tooth 32 dp gear with matching 20 degree pressure angle.
The iron casting for the 150 tooth gear.
Blank cast iron gear wheel. by Andy, on Flickr
Machining.
Machining the gear casting by Andy, on Flickr
Videos, click on the picture to open the Flickr website.
Machining the gear casting by Andy, on Flickr
Machining the gear casting by Andy, on Flickr
Ready for the teeth to be cut. The bore is 9/32".
Gear casting ready to have the teeth cut by a local gear cutting firm. by Andy, on Flickr
I was asked to provide a steel disc to support the delicate cast iron gear blank.
Steel disc to support the iron gear wheel by Andy, on Flickr
The steel disc was machined to be just a few thousandths below the root circle diameter of the iron gear wheel as can be seen with the edge of the casting projecting beneath the steel disc.
Steel disc to support the iron gear wheel by Andy, on Flickr
I dropped the casting and supporting steel disc in on a Monday and the gear was ready for me to collect two days later.
150 tooth gear cut by Redditch Gears. by Andy, on Flickr
Andy
crueby:
Great start! The castings look to be very good quality. Watching along... :popcorn:
Dave Otto:
Cool project Andy! Looking forward to following along.
My good friend Max built one of these a number of years back and it has always been a good runner. He added heavy counter weights to the crankshaft which really smoothes out the rocking motion when running. If I remember correctly he originally made a built up crank shaft with taper pins and loctite, the crank failed in short order. So after that he made a one piece crank for it. Some claim that a two into one exhaust is required for proper running but my friend's engine seems to run just fine with two individual stacks. It is also important to adjust the piston for equal compression on each end of the cylinder. If there is any interest I could get photos and maybe a video of his engine.
Dave
Jasonb:
Will follow along as I too have always liked the Mery
Jo:
8)
Nice to see your set of Mery Castings seeing the light of day Andy :pinkelephant:
They did a good job on that gear :ThumbsUp: I will be practising on a blank before I cut mine. There is nothing worse than getting a gear with a half tooth :toilet_claw: I like their request for the two steel supports I will try to remember that :)
Jo
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