Engines > From Kits/Castings
Mery Explosive Engine
Jasonb:
It would be interesting to know what method they used to cut it, if a gear planer or shaper then the force against the gear would be more than hobbing or as we do it with involute cutters. A bit of MDF would be enough to support the casting for small 32DP Involute cutters Or just back up the far edge with a solid stop which I have done in the past.
PS Only one backing support Jo.
Chipmaster:
Thanks for your comments folks.
Yes Crueby the castings are excellent and Dave, I would gratefully receive any advice your friend Max can give, photos and videos most welcome. There seems to be some gaps in the set of drawings or items I don't understand :ThumbsUp:.
My early efforts at making model engines made me wary of fabricating crankshafts because a couple of my fabricated cranks failed, one when the engine backfired and the other went banana shape due to the heat of silver soldering. I then switched to carving crankshafts from solid flamecut profiles but that's a slow process. However, in recent years I have used silver solder to assemble a few crankshafts that have survived.
Jo & Jason - I think Redditch Gears said they used a gear shaping machine (not a single point shaper) I'll ask them what method and machine they used when I next drive by.
Andy
Chipmaster:
This is the engine's cast iron base or body, it's just like the trunk guide of a steam engine.
IMG_8436 by Andy, on Flickr
To bore the trunk guide using my Chipmaster lathe I had to mount the casting on its side as other Mery builders had pictured in their builds on the Internet. Standing upright the casting's centreline was too high for the lathe. At last I had found a use for a piece of 1/2" thick steel plate that had been leaning against the wall in my garage for twenty years. If I removed the topslide and attached the steel plate to the cross slide I could mount the casting sideways on two angle plates.
Tabs by Andy, on Flickr
To start the feet were milled flat. Relying on the the 3 machined stubs (white arrows) projecting above the casting as sold by Marti Models which were parallel to the horizontal centreline of the trunk guide.
IMG_8482 by Andy, on Flickr
IMG_8479 by Andy, on Flickr
Four 1/4" clearance holes.
IMG_8516 by Andy, on Flickr
The casting was bolted on to a piece of gauge plate 3/8 x 4 x 18" (expensive) that would be essential for holding the casting for various machining sessions.
8518 by Andy, on Flickr
Steel plate bolted to the cross slide.
IMG_8529 by Andy, on Flickr
IMG_8530 by Andy, on Flickr
I spent a long time measuring and marking up the casting, I found some of the measurements in the drawings for the engine body to be either impossible or my casting was the wrong shape. Nothing insurmountable just perplexing. Anyway the casting is pictured below, securely held / rigid ready for boring the trunk guide section.
IMG_8533 by Andy, on Flickr
IMG_8534 by Andy, on Flickr
Jo:
You are moving along really fast when we think about how long you have had these castings.
I see you have a taper turner on the back of your Chipmaster :-X I couldn't see a DRO read head :headscratch:
Jo
john mills:
methods of cutting gears what the cutting process is used what the cutting forces are .the fallows type shaper shaving the teeth or hobbing
John
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