Model Engine Maker

Engines => From Plans => Topic started by: gbritnell on July 03, 2018, 01:20:10 AM

Title: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 03, 2018, 01:20:10 AM
Since the MEM Corliss drawings were posted quite some time back I had mentioned that it would be on my to-do list. Well I got started on it this morning but not in the usual fashion. I took the smallest screw size on the drawings, 0-80, and scaled it to M1.0 x .25. The scale factor came out to a little less than .40 but I rounded it off and went with that number.
The majority of the screws on the full sized model are 1/8 (5-40) these work out to M1.2 x .25. The cylinder is made from 12L14 steel. I trued it to size then drilled and bored the bore, .45 inch.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 03, 2018, 01:30:05 AM
The porting from the valve chamber on the full sized model is drilled with a 1/16th drill. With my scale factor this came out to .025. I laid out the drawing to see exactly how the porting looked. Not having a center drill long enough or small enough I went with my only option. I drilled out a piece of 3/16 brass rod for the .025 diameter drill. I turned a 15 degree taper on the nose to match the port angle. The drill was cleaned up and Loctited into the brass. I left only enough sticking out to break through into the cylinder. Before using it I pushed on it with my fingernail and it seemed quite rigid.
My mill only goes up to 2600 rpm so that's the best I can do for this small drill. I set the cylinder on 15 degrees and picked up the center of the valve hole. I cranked up the spindle and very lightly touched the drill to the bottom of the valve hole. Once I felt that it had centered itself I felt my way through the metal into the cylinder. There are 5 holes spaced .037 apart. When I got done the holes looked quite uniform and in line. Whew!!!! I would hate to have put 8 hours into this cylinder only to have the small drill wander or break.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: b.lindsey on July 03, 2018, 01:35:23 AM
Another tiny project to look forward to. The penny shows how small that cylinder is....wow. I'm hooked already George!!

Bill
Title: Re: Another MEM Corliss (in .40 scale)
Post by: crueby on July 03, 2018, 01:40:51 AM
Oh my!!  What a wonderful project!  As usual, will be watching this one with a prop under my chin to limit the drooling.


 :popcorn: :popcorn: :popcorn: :popcorn:


Any chance I can get you to do a teensy Marion shovel to fit in the bucket on mine?   :Lol:


 :cheers:
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Craig DeShong on July 03, 2018, 02:35:04 AM
The start of another amazing project.  Can't wait to see the future installments.  :popcorn:
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Larry on July 03, 2018, 04:13:36 AM
Have thought about giving the MEM Corliss a try but not to this scale. Like the Wheat Penny ! Will follow with interest.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: kvom on July 03, 2018, 11:49:19 AM
Scaling 0-80 screws down by half?  Oh my!   :ShakeHead:

I'll look forward to seeing it at NAMES.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: steamer on July 03, 2018, 03:11:20 PM
I love it George!

Dave
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Dave Otto on July 03, 2018, 03:34:10 PM
Nice start George, looking forward to following along with this one.


Dave
Title: Re: Another MEM Corliss (in .40 scale)
Post by: 10KPete on July 03, 2018, 05:42:21 PM
This is nuts! Making things sooo tiny on purpose!!

George, I envy your ability to work with such small bits. You must have been a watch maker in a previous life!

 :lolb:

 :popcorn: :cheers:

Pete
Title: Re: Another MEM Corliss (in .40 scale)
Post by: scc on July 03, 2018, 07:32:20 PM
I'm hooked :popcorn:
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 06, 2018, 02:32:39 PM
I have the heads finished, front and rear with packing nut. I finished the crosshead guide although the bore didn't come out too nicely. I think the reamer was dull and it must have rubbed the chips as it went. Yesterday I finished the main frame. There were options to make it in two pieces but with the small size it didn't use up much metal so for simplicity sake I went with the one piece. This morning I finished the two pedestals that the cylinder mounts onto.
I haven't decided on how I'm going to make the flywheel. The drawings show it fabricated with hub, spokes inner outer rim and outer covering rim. I suspect it was made that way to simplify machining the larger wheel.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: steamer on July 06, 2018, 02:39:25 PM
I believe that was the original intent George, to make building the wheel easier and less expensive.  Bob ( maryak)  will be along shortly I'm sure.

Dave
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 06, 2018, 02:47:13 PM
Here's a couple of close up pictures of the frame. For some reason my good camera decided not to take good pictures any longer so I had been using my backup everyday point and shoot camera. This morning I 'rebooted' my good camera and went back to the original settings and all of a sudden the pictures are coming out better. Gotta love these electronic instruments.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: steamer on July 06, 2018, 02:48:53 PM
When I grow up I wanna make parts just like you George!    :ThumbsUp:


Sweet!...
Title: Re: Another MEM Corliss (in .40 scale)
Post by: vcutajar 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
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Ramon 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
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell 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.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Dan Rowe 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
Title: Re: Another MEM Corliss (in .40 scale)
Post by: crueby 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:
Title: Re: Another MEM Corliss (in .40 scale)
Post by: b.lindsey 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
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell 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.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell 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.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell 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.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell 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.

Title: Re: Another MEM Corliss (in .40 scale)
Post by: b.lindsey 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
Title: Re: Another MEM Corliss (in .40 scale)
Post by: crueby on July 09, 2018, 07:26:18 PM
Holy Micron, thats small!
Wow just doesn't cover it....
 :popcornsmall:
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Admiral_dk 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.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: jeff l on July 10, 2018, 12:54:31 AM
Happy to see that you are building a Corliss , great job !
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Tennessee Whiskey on July 10, 2018, 07:35:14 PM
Iím sitting here trying to figure out something to say and all I can think about is: ďhe just threaded a paper clip, OMGĒ . I canít wait to tell some of my buddies that. A freaking paper clip. George, have you ever considered watchmaking? Iím still babbling: a paper clip.

Cletus
Title: Re: Another MEM Corliss (in .40 scale)
Post by: kvom on July 10, 2018, 11:49:46 PM
I'd have had to buy a pack of 3/64" dowel pins from McMaster as there's no way I'd ever get a paper clip straight.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: crueby on July 11, 2018, 12:00:29 AM
Now we have to get him to make us all paperclips with tiny nuts threaded on the ends, back in the shape of a paperclip of course!
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Craig DeShong on July 11, 2018, 02:22:38 AM
Your work is just amazing George  :ThumbsUp: :ThumbsUp: :ThumbsUp:
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 11, 2018, 04:38:30 AM
First of all thanks everyone for the gracious comments.
The flywheel scales down to 2.90 inches diameter. The spoke cross section is .100. The full sized flywheel is a fabrication of the hub, spokes, inside outer rim that the spokes mount to then a finish ring on the outside.
To fabricate the flywheel would have meant silver soldering .094 spokes into the hub and rim. Even with careful fixturing there is a possibility of warping. On the larger wheel that wouldn't be too much of a problem because the flywheel would be rigid enough to chuck and cut true but with this little one there is no good way to correct any out of true condition.
With that in mind I decided to make it from solid steel. I increased the spoke cross section from .100 to .135. With larger wheels I start with the blank in the chuck and cut the recesses in the part but with the radius in the corners of the hub and rim it takes several tools changes to finish it. One tool is needed to rough to depth (trepanning) then the other tools for finishing the inside and outside radii.
I decided to mill the whole wheel. I chucked it in the lathe and faced both sides to size. I also drilled and reamed the center hole. (.156 diameter) I set up the rotary table and indicated it true. I then clamped an old aluminum fixture plate to the rotary table. I milled a center hole into the plate and drilled and tapped for some small clamps. I turned up a plug for the center hole that would locate the wheel blank perfectly on center.
I left extra material on the outside edge of the rim to clamp to. I milled to depth leaving stock for finishing the fillets in the corners.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 11, 2018, 04:46:30 AM
The part was then turned over and the same machining completed. The next step was to center drill and drill out the inside corners. I stayed away from the tangent point so this could be finished with a .187 end mill. With the pilot holes complete I started roughing the spokes staying about .006 away from the finished dimensions. Once the material was roughed out I went to my finish dimensions. The hardest part of this process is cutting the inside of the rim. If you leave even .001-.0015 stock then it's really a lot of work filing and finishing to blend it in. If you go the other way by the same amount it leaves a step in the part.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: crueby on July 11, 2018, 04:50:48 AM
More stunning work...


 :popcorn: :popcorn: :popcorn: :popcorn:
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 11, 2018, 04:52:16 AM
I was more than happy with the way everything blended so the part was then mounted in my 3 jaw chuck and the extra material that I had left for clamping was reduced leaving about .005. The chuck isn't accurate enough to take the part to the finished size so I put it back on the fixture plate that was still set up on the rotary table. Using an end mill I cut the remaining material off the wheel.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 11, 2018, 04:53:43 AM
All that remains is to put a radius on the edges of the spokes and drill and tap for a set screw.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Ramon on July 11, 2018, 05:28:14 AM
Just caught up George but all very much worth waiting for  :ThumbsUp:

Thanks for the heads up on the tap. That type is new to me. Though never used I have a couple of fluteless forming taps from work days which require a larger hole and power feed which look similar -  I guess these ones are designed mainly for through holes in thin material - do you need to keep withdrawing to clear any swarf ?

Super machining on the flywheel - at sub 3" those spokes would have need a delicate touch for sure, a lovely result indeed.

Love the use of the paper clip too  :praise2:- I've used wire coat hanger material to make 8BA studs in the past but this takes it all to a new level  :o.

Yep, it's going to be a little 'Gem' for certain  :ThumbsUp:

Regards - Tug
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 11, 2018, 12:41:53 PM
HI Tug,
Thanks for the reply. Usually with any small tap, fluted or otherwise, I back them out repeatedly to clear the chips. As most builders have found the taps go in very nicely, it's when you're backing them out that they start binding up. I use my headband magnifier when using the small taps. It gives me better control at keeping the tap square.
gbritnell
Title: Re: Another MEM Corliss (in .40 scale)
Post by: b.lindsey on July 11, 2018, 12:52:38 PM
Lovely work as always George on the flywheel !!

Bill
Title: Re: Another MEM Corliss (in .40 scale)
Post by: steamer on July 11, 2018, 01:09:53 PM
 :popcorn:
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 11, 2018, 07:42:03 PM
Corners radiused and polished. Just the set screw remains.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: zeeprogrammer on July 11, 2018, 07:58:07 PM
I've been  :popcorn: from the beginning. I just don't know what to say.

Amazing work!
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Craig DeShong on July 16, 2018, 12:57:55 AM
Lovely George, just lovely.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: toolznthings on July 16, 2018, 01:09:25 AM
Hi George,

Was not paying attention till you mentioned your new project when we talked today. Great work as always !
Will follow along as you go.

Brian
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 16, 2018, 05:22:56 PM
Bolts, bolts and more bolts. I have most of the large parts made so I'm starting to bolt things together to see if everything lines up. On the full sized model the majority of fasteners and threaded holes are just spelled out as 1/8 to allow metrification of the build. In my world 1/8 translates to 5-40 and when multiplied by .40 becomes .05 which the closest thread size is M1.2 (.047) so all of the bolts that you see are that size with .078 hexes. I had to make up an open end wrench to tighten the bolts on the inside of the cylinder mounts.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Kim on July 16, 2018, 05:54:12 PM
Wow, George,
Just, wow...

Kim
Title: Re: Another MEM Corliss (in .40 scale)
Post by: crueby on July 16, 2018, 06:02:42 PM
Excellent!!
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 16, 2018, 06:46:08 PM
Some pictures of the major parts assembled. I had counterbored the mounting holes on the base plate leaving .100 of material. I then made some special M1.2 screws to go up through the base and into the engine. These are topped off with M1.2 nuts. The full sized version has the base tapped and then the bolts go through from the top. I didn't want to chance tapping the aluminum with the small tap.
Everything lines up nicely so I can start making the crank pin and the wrist pin for the crosshead.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: crueby on July 16, 2018, 07:03:38 PM
Wow, really coming together wonderfully!
You could call this one your Pocket Corliss.
 :popcorn: :popcorn: :popcorn:
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Ye-Ole Steam Dude on July 16, 2018, 07:15:17 PM
That flywheel really looks good with the other parts. Love all your work.

Have a great day,
Thomas
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 20, 2018, 12:36:08 AM
Starting on the tiniest of bits now. This is the eccentric, hub, spindle and a M1.2 nut. I thought I'd throw the penny in for a comparison. The square on the spindle is .050 across the flats. I drilled the hole in the eccentric plate then filed it out square.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: b.lindsey on July 20, 2018, 12:53:02 AM
Beautiful George. Thank for the penny too. That really helps with seeing how small these parts are.

Bill
Title: Re: Another MEM Corliss (in .40 scale)
Post by: zeeprogrammer on July 20, 2018, 01:13:08 AM
Starting on the tiniest of bits now.

 :lolb: :lolb: :lolb:

Sorry. It's just that we need another word for tiny when it comes to you.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: crueby on July 20, 2018, 01:35:03 AM
Wow. Again.  I usually call bits that small 'swarf'.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: propforward on July 20, 2018, 02:30:34 AM
Stunning and inspirational!
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 21, 2018, 04:07:52 PM
The valve bits and pieces are made. The valves I made from brass because the block is steel. The links were drilled and profiled on the end of a piece of round stock standing up in my mill vise. They were then sawn off with a small slitting saw. I have a small home-made hand vise that I clamped them in to file the radius on the center shaft area. All this was done with my Optivisor headband magnifier.
The small levers were made in multiple steps. I started by drilling the center hole, .047 diameter, into the end of a piece of .312 round steel in the lathe.
The levers required another hole (tapped M1. x.25) .125 from the center hole. On the first link I waited until the milling was done but the part was so small that I couldn't see to center the drilled hole so I used plan B. I took the piece of stock and stood it up in my mill vise, indicated it true then drilled the hole (.031 diameter). The stock was then transferred to my dividing head but now I needed a way to position the stock so that the two holes would be on a true horizontal line. The difference in the diameters of the two holes is .016 so I placed the drills used to make the holes into the drilled holes and indicated across the shanks until I got the required .008 difference. The dividing head was locked at -0- degrees so to orient the stock while indicating I left the chuck just slightly loose so that I could turn the stock with pliers.
The stock was then milled down until the .090 width was achieved. While at this setting the stock was rotated 8 degrees to cut the taper. The dividing head was then rotated 90 degrees and the flat on the top of the lever was milled.
A drilled and tapped hole is needed for the clamp screw so the end of the part was picked up and the table moved to the proper location.
The stock was then put back in the lathe to part off the piece. A little bit of filing was done to break the edges and put a small radius on the corners where the link attaches to.
The part was then clamped in the mill vise and using a .013 slitting saw I cut the slot across the end.
The valves were turned and the center area was milled halfway down (.050) While at this setting a small witness was cut in the end (.015 deep) so that the valves can be set after assembly. The witness will show the orientation of the relief in the valve.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: cfellows on July 21, 2018, 05:01:21 PM
Lovely work, George.  The MEM Corliss is such a pretty engine and your touch and attention to detail makes it even better.  I especially like your flywheel.

Chuck
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 21, 2018, 06:29:09 PM
Here's a shot of the valves and levers on the engine. All the bolts to hook the levers to the links will have to be made by hand because they need unthreaded area that go through the links. Presently I'm using M1 x .25 stainless bolts that I got from Model Motorcars. They're 3mm long and are fully threaded.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: b.lindsey on July 21, 2018, 06:37:53 PM
What a great picture George!! Really coming together.

Bill
Title: Re: Another MEM Corliss (in .40 scale)
Post by: crueby on July 21, 2018, 07:43:16 PM
More stunning work!
Title: Re: Another MEM Corliss (in .40 scale)
Post by: cfellows on July 22, 2018, 04:09:29 AM
Hey George, love what your doing here.  Just curious why you didn't make the cylinder assembly out of brass?

Chuck
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 26, 2018, 02:47:05 PM
Hi Chuck,
My thought was if I made any one of the major parts from brass I would have had to make all of them from brass, crosshead guide, flywheel etc. so I went with steel and then made the moving parts, piston, crosshead etc. from brass.
I have all the valve linkage for the cylinder made so I assembled it to see what it looks like.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: cfellows on July 26, 2018, 04:13:07 PM
The steel looks good.  Iíve been contemplating some additional steel parts on my Maudslay to match the flywheel... maybe the base.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: zeeprogrammer on July 26, 2018, 04:15:36 PM
That second picture says it all. Wow.  :o
Title: Re: Another MEM Corliss (in .40 scale)
Post by: crueby on July 26, 2018, 08:06:07 PM
Oh. My.


 :praise2:
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Ye-Ole Steam Dude on July 26, 2018, 08:40:56 PM
Hello George,

Your work is beyond comprehension. Tell you what I did, I went and took a penny out of my change bowl and brought it back to the computer and tried to get a sense of what you have created. Just wonderful to see, thank you.

Have a great day,
Thomas
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Kim on July 26, 2018, 08:51:47 PM
Truly amazing, George!
Kim
Title: Re: Another MEM Corliss (in .40 scale)
Post by: vcutajar on July 26, 2018, 09:34:02 PM
OMG   :praise2: :praise2:

Vince
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Ramon on July 26, 2018, 10:48:28 PM
I've been wondering George if I should try to make the linkage on my Corliss build more scale like - now I know I have to  :o

Absolutely superb workmanship :praise2: :praise2: and truly wonderful miniaturisation.

Can't wait to see that working for sure  :ThumbsUp: :ThumbsUp:

Tug
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Craig DeShong on July 28, 2018, 09:32:37 PM
Words fail me.   :popcorn: :popcorn: :popcorn:
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on July 30, 2018, 02:48:14 PM
Thank you one and all for the gracious comments. I enjoy presenting my work to my peers. Our community is shrinking so it's great to share and discuss on forums like this.
Attached is a picture of the throttling valve I just made. The body was turned with the neck and hexes machined toward the valve handle. The center hole was drilled for a M1.2 shaft. The barrel is .156 diameter was machined as part of the stem. The input tube was machined with the hex to simulate part of the valve body. The tube and flange going to the engine was machined the same way with the hex. I put counterbores in the body to accept these pieces by soft soldering them together. When ready I put a dab of flux and a small sliver of solder at the joint then heated the assembly up until I saw the solder wet. The problem is it wicked down to the valve and when it cooled the valve stem was soldered solid. I then heated it back up to release the valve stem. I polished all the solder from the bore and the valve head then coated it with a light film of oil upon assembly. I then heated the part again counting on the solder that had already flowed onto the valve body to fuse the pieces together, which it did.
I cleaned up the excess solder with an Exacto knife then polished the valve and handle.
The black mark on the valve handle is the wide open position. The valve handle is .375 diameter.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on August 01, 2018, 02:58:00 PM
I'm continuing with the build of the Corliss. I completed the Walnut base and mounted the engine to it. I put fluting on the stanchions to add a little character. 
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on August 01, 2018, 03:02:51 PM
Next up will be a governor. It won't control the valve linkage like the larger versions but I thought it would look neat spinning away while the engine was running.
I drew something up that looked somewhat to scale and the miter gears came out to 72 D.P. I had a cutter made up for a project years ago and it was close enough to the proper width for the small end of the tooth. The gears have 16 teeth and are .243 O.D.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: crueby on August 01, 2018, 03:08:52 PM
 :popcorn:

Title: Re: Another MEM Corliss (in .40 scale)
Post by: zeeprogrammer on August 01, 2018, 03:36:15 PM
Then a throttling valve, beautiful base and stands, and now a governor. Just wow.  :popcorn:
Title: Re: Another MEM Corliss (in .40 scale)
Post by: vcutajar on August 01, 2018, 08:36:41 PM
That is a real gem George.  Looking forward to see it with the governor.  I chickened out on mine and did not do it.

Vince
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on August 02, 2018, 03:46:20 PM
I started on the governor parts, first the gears and then the column. What you see is two pieces. I turned, drilled and reamed the lower piece then put it on the mill to cut the square area for the gears. It then went back to the lathe to cut the taper and flange. The top was threaded 6-40 to receive the upper part of the column. Assembling the gears I found the lengths needed to be tweaked to get a proper mesh.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: b.lindsey on August 02, 2018, 03:56:13 PM
That will add another nice focal point for the engine, not that it is lacking for "wow" features as it is :) Very nice George.

Bill
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Tennessee Whiskey on August 02, 2018, 07:21:18 PM
Iím just blown away by the whole thing George. Gee, youíre stepping up to a 6-40 thread size; kinda big for you isnít it? 8)

Whiskey
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on August 04, 2018, 12:43:59 AM
I got some more parts made. The main shaft is .062 stainless steel. It's threaded M1.2 x .25 on the top to hold the upper weight arm bracket. The lower bracket was made in one piece, incorporating the weight. I ground a forming tool bit to shape the radius next to the bracket. The remainder was filed to shape. The tiny decorative nut at the top has a .078 hex and holds the upper bracket to the main shaft.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: crueby on August 04, 2018, 01:03:36 AM
I need to order a new box of "Wow"'s.


 :popcorn:
Title: Re: Another MEM Corliss (in .40 scale)
Post by: zeeprogrammer on August 04, 2018, 03:45:46 AM
I need to order a new box of "Wow"'s.

Well put. And get me a case too.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Craig DeShong on August 04, 2018, 04:15:00 AM
I need to order a new box of "Wow"'s.

Well put. And get me a case too.

Me too !
Title: Re: Another MEM Corliss (in .40 scale)
Post by: 10KPete on August 04, 2018, 05:18:09 AM
And three!  Just amazing especially when we all know just what that kind of work takes.
Bravo!!

Pete
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on August 07, 2018, 11:50:28 PM
With the flathead work out of the way I got back on the Corliss. I had reservations about making the ball arms with the hinge pad in the middle.
I first turned the long end, .046 diameter x .347 long, then transferred the collet chuck to the mill. I milled a flat at 0 and 360 but only enough to drill the hinge holes, .040 diameter. I then slowly worked the stock down until I had a section .075 square. The collet was then screwed back onto the lathe spindle and the short area of round between the hinge point and upper joint was turned. It was here I expected the tool to grab and twist the whole thing like a pretzel, but it didn't. Once the shaft was turned I put the collet back in the mill and indicated across the flat of the hinge joint. Using a sharp .125 end mill I cut the upper pivot joint to thickness, .026 wide. I left a couple of thou. to file and fit it to the upper bracket.
The collet chuck was once again put on the lathe and the piece was parted off. I then filed the radius on the upper end and fitted the flat area to the bracket.
The balls are .187 diameter bronze that I have had for years when I used to do more steam stuff. I sorted through my split collets to find a 3/16ths one and clamped the ball in the 3 jaw chuck. I drilled about halfway through with a .046 drill. The ball was fixed to the shaft with Loctite.
One more to go.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Admiral_dk on August 08, 2018, 12:45:36 AM
Oh man, the potential for failure in this size is immensely  :o and while I gotten used to have the CNC router at work do hole diameters down to 0.6 mm. in PCB material without any problems, I do remember the swearword ratio before when doing it by hand  :cussing:

I really like your approach with drilling when you have a bit more material, but it is still not easy.

How "fast" is your mill ? - I'm sure one of the major reason the CNC do a much better job than I can do manually is the extreme high RPM's it is running (20-30K) as this prevents much of the tendency these tiny drill bits has to wander compared to the old manual drill (2-3K) + high feed rate.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on August 08, 2018, 03:35:45 AM
Top speed on my mill is 2500. I have learned to drill down to .025 with it without breaking drills. For milling with really small end mills I have a speeder head that was designed by Jerry Howell. It consists of a high speed spindle that fits into a .875 R-8 collet and is driven by a 24 volt DC motor mounted on a bracket off to the side. The way I have it set up I can get 7500 rpm out of it. It works good for .062 and .032 end mills. It takes a lot of feel but my mill is small enough and sensitive enough that I can feel the cutter working.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on August 08, 2018, 06:40:18 PM
All is finished on the governor except the pulley. All the joints are nice and free but it still doesn't have enough weight to return the balls so I'll add a tiny spring above the weight on the shaft. Now I need to disassemble the crankshaft so that I can trim down the eccentric. The rods will need to be moved in also. This will give me enough room between the eccentric and the flywheel to put the other pulley.
Title: Re: Another MEM Corliss (in .40 scale)
Post by: Ye-Ole Steam Dude on August 08, 2018, 07:33:44 PM
Another WOW and a "that's cool".

Have a great day,
Thomas
Title: Re: Another MEM Corliss (in .40 scale)
Post by: gbritnell on August 10, 2018, 04:42:34 PM
Ok the engine is finished. I gave a short synopsis in the finished engine section. Here's the final glamour shots of the engine with governor.
Thanks everyone for watching and commenting.
gbritnell