Author Topic: Another MEM Corliss (in .40 scale)  (Read 3218 times)

Offline vcutajar

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Re: Another MEM Corliss (in .40 scale)
« Reply #15 on: July 06, 2018, 03:00:04 PM »
Wow George.  You are going to have it finished very soon.  So what's the diameter of the flywheel?  3.5" ?

Vince

Offline Ramon

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Re: Another MEM Corliss (in .40 scale)
« Reply #16 on: July 06, 2018, 03:07:43 PM »
Lovely work George, some real nice machining there  :ThumbsUp: but hmmmm? - not quite so sure about the size  :o

That's going to be another little 'Gem' for certain but I sure don't envy you having to tap all those small holes  ::)

Looking forwards to seeing this progress

Regards - Tug
"I ain't here for the long time but I am here for a good time"
(a very apt phrase - thanks to a well meaning MEM friend)

Offline gbritnell

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Re: Another MEM Corliss (in .40 scale)
« Reply #17 on: July 06, 2018, 04:22:34 PM »
Hi Vince,
The flywheel will be 2.90 inches. (73.66mm)
Actually Tug the holes haven't been too bad. I figured somewhere along the build I would hear that 'crack' and then have to bin the part and start over. It's easier to remake the part then to have to buy another tap. In those small sizes you're looking at about $28.00.
I got a mm1 x .25 high speed steel tap from ebay. I haven't seen one ground like this one before. It's the full diameter of threads and just the tip is ground to create the cutting edge. It's pretty rigid compared to one with flutes the whole length of the tap.
Talent unshared is talent wasted.

Offline Dan Rowe

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Re: Another MEM Corliss (in .40 scale)
« Reply #18 on: July 06, 2018, 04:35:32 PM »
George,
I have been using form taps for the very small sizes. The price on ebay is about $15-$17 for a M1x.25 tap.

Dan
ShaylocoDan

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Re: Another MEM Corliss (in .40 scale)
« Reply #19 on: July 06, 2018, 04:48:40 PM »
Hi George,


Have you ever been to the Mariners Museum in Virginia? With your passion for miniature models, you would love the Crabtree Collection of ship models, so much small detail that the display cases have magnifying glasses built in.


 :popcorn:

Online b.lindsey

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Re: Another MEM Corliss (in .40 scale)
« Reply #20 on: July 06, 2018, 05:45:23 PM »
Rapid progress George and things look amazing. After making that statement about not hearing the "crack" of a broken tap, I hope you had some wood nearby to knock on :)

Bill

Offline gbritnell

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Re: Another MEM Corliss (in .40 scale)
« Reply #21 on: July 09, 2018, 05:30:36 PM »
A progress report.
Piston, piston shaft and crosshead finished. The piston and crosshead are both made from brass. The piston shaft is made from stainless steel. The piston shaft is threaded on both ends and screwed into the piston and crosshead. The thread is 2-56.
Talent unshared is talent wasted.

Offline gbritnell

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Re: Another MEM Corliss (in .40 scale)
« Reply #22 on: July 09, 2018, 05:36:19 PM »
The next pieces were the cylinder supports. I machined the length and width onto a piece of longer stock. This was so I could clamp it in the vise, machine the recesses, drill the holes then cut them off without having to hold the small pieces individually. The recess under the flange was cut with a Woodruff key cutter. After machining the two parts were cut off the bar and then set into the vise. The flanges that the cylinder mounts to is narrower than the bottom flange so I put the parts in the vise and rested the bottom flange against the vise jaw. Both parts were cut to the identical height.
Talent unshared is talent wasted.

Offline gbritnell

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Re: Another MEM Corliss (in .40 scale)
« Reply #23 on: July 09, 2018, 05:43:25 PM »
Up next were the connecting rod and crankshaft. The connecting rod started from a piece of round stock. I put it in my dividing head then slotted, milled to size and drilled the wrist pin hole. From there it went into the lathe and had the tapered center shaft machined. I only stuck the piece of stock out far enough to do half of the taper because the large part of the taper is only .125 diameter. I then pulled out the stock and cut the second half of the shaft.
From the lathe it went back into the dividing head. I put the drill through the wrist pin hole and indicated it flat. I then cut and drilled the crank end of the shaft. The part was then cut from the bar and the radius and taper on the wrist pin end was cleaned up.
Talent unshared is talent wasted.

Offline gbritnell

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Re: Another MEM Corliss (in .40 scale)
« Reply #24 on: July 09, 2018, 06:03:44 PM »
I had some time yesterday so I started on the eccentric and strap. The strap on the larger model has the big end made in two pieces so that it can be clamped over the eccentric, which is slotted to locate the strap. Reducing the size prevented the same construction. I made the eccentric with one flange.
When I turned up the part I left enough stock so that once the eccentric was parted off I could then face the remaining material and cut the outer flange (. 025 thick) The eccentric and outer flange were mounted on the crankshaft then drilled and countersunk for a 0-80 flat head screw. Upon assembly I can leave the flange loose until the timing is set and the 1-72 set screw is tightened then the flange can be secured.
The link rods from the eccentric strap and from the rocker arm to the valve bell crank plate needed to be around .050 (.125 x .40). The drawings call for threaded ends, both into the eccentric strap and the clevis which mounts to the rocker arm. The closest thread to .050 is M1.2 x .25 (.047) The problem is the shafts couldn't be turned 1.80 and 1.20 long respectively so I had to find some material around the proper diameter. Measuring parts and pieces I had on my workbench and scrap bin turned up an unlikely source for the stock, a larger paper clip. It happened to be .0455 diameter. Just the size that's recommended for threading. I straightened the clip as well as I could then clamped it in my mill vise until it the bumps were almost gone. I then lightly tapped on it with a hammer until almost perfectly straight and true. I then made a split collet to hold the material so that I could die cut the threads on the ends.
The clevises were then machined on the end of a bar, parted off then drilled and tapped M1.2. This also required a split collet for holding in the lathe to drill for the tap.

Talent unshared is talent wasted.

Online b.lindsey

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Re: Another MEM Corliss (in .40 scale)
« Reply #25 on: July 09, 2018, 06:20:01 PM »
Amazing George!! It's even smaller that I had originally thought. Paperclips for rod material, that may be a first  :noidea:

Bill

Online crueby

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Re: Another MEM Corliss (in .40 scale)
« Reply #26 on: July 09, 2018, 07:26:18 PM »
Holy Micron, thats small!
Wow just doesn't cover it....
 :popcornsmall:

Offline Admiral_dk

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Re: Another MEM Corliss (in .40 scale)
« Reply #27 on: July 09, 2018, 09:17:52 PM »
Quote
Wow just doesn't cover it....

I'm not so sure that Wow doesn't cover several pieces here this small easily  ;)

Sorry George but I couldn't help myself teasing Chris in the middle of yet another fantastic build from you - but I do understand why they have problems with finding new applausive words to describe your work ..... just look at the small Phillips headed screw and it looks way to big here  :o

You certainly raised the bar again.

Offline jeff l

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Re: Another MEM Corliss (in .40 scale)
« Reply #28 on: July 10, 2018, 12:54:31 AM »
Happy to see that you are building a Corliss , great job !

Online Tennessee Whiskey

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Re: Another MEM Corliss (in .40 scale)
« Reply #29 on: July 10, 2018, 07:35:14 PM »
Im sitting here trying to figure out something to say and all I can think about is: he just threaded a paper clip, OMG . I cant wait to tell some of my buddies that. A freaking paper clip. George, have you ever considered watchmaking? Im still babbling: a paper clip.

Cletus