Author Topic: JC attempts the MEM Corliss  (Read 3133 times)

Offline crueby

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Re: JC attempts the MEM Corliss
« Reply #15 on: November 01, 2020, 01:46:02 AM »
Great start, always nice to see another build of this engine.  Will be watching along!
 :popcorn: :popcorn: :popcorn:

Online JCvdW

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Re: JC attempts the MEM Corliss
« Reply #16 on: November 09, 2020, 09:52:52 AM »
Thinking ahead on how to assemble the flywheel, I decided to also hold the hub in the lathe end stock using a Jacobs chuck, the way Arnold did it. So far the axle hole in the hub is only drilled, and not perfectly straight. I therefor mounted the hub in the four yaw chuck and bored the hole to be straight and concentric, but still slightly under size.

The runout of the Jacobs chuck is about 100 micron, so I decided to turn a temporary concentric arbour for the hub by mounting a piece of scrap in the Jacobs chuck. The MT2 taper of the chuck does not take a drawbar, so I supported the work with a dead centre in the end stock, and turned down the arbour for a snug fit of the hub.



With all the preparation work out of the way, it was time to turn the inner rim of the flywheel. Quite a lot of material to remove! After the warping I saw on the outer rim during bulk material removal, I decided to first turn and bore the inner rim to about 1 mm from final dimensions, before aiming for the final dimensions.




Many hours and lots of swarf later, the inner rim has the correct inside diameter and thickness, ready for the spoke holes to be cross drilled. The outside diameter is still oversize, to be turned down once the spokes are in place.





Cross drilling the spoke holes, using the same indexing plate used for the drilling the spoke holes in the hub.





Test fit of the spokes and hub before glueing with Loctite retaining compound. So far so good.



Offline Ramon

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Re: JC attempts the MEM Corliss
« Reply #17 on: November 09, 2020, 01:14:41 PM »
That's a good start JC, looks very promising  :ThumbsUp:

Keep it coming  ;)

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)

Online JCvdW

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Re: JC attempts the MEM Corliss
« Reply #18 on: November 09, 2020, 07:03:21 PM »
Thanks for the feedback Tug!

Before glueing the spokes, I checked the concentricity of the hub by running the assembly on the lathe, and everything looked perfect. So I disassembled the lot, and cleaned it for glueing. Great was my disappointment after glueing the spokes, that the hub was quite a bit off centre!.

By then the Locktite was rock solid, and I had to use a blow torch to get the spokes out. I realised that I needed finer control to position the hub, and decided to thread the ends of the spokes. With nuts on the ends of the spokes I could then accurately dial in the hub to run true.





I could then glue the spokes by removing one at a time, glueing and then locking it back into place with one eye on the dial indicator. The end result is a hub that runs true within 20 micron on the one side of the wheel. I eyeballed the hub on the head stock side of the wheel while running the lathe at moderate speed, and it looks ok as well. Final boring of the axle hole should take care of any residual skewness of the hub. Once the glue has cured, I can proceed to saw off the spoke ends and machine the outside diameter of the inner rim to fit the outer rim.



Offline crueby

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Re: JC attempts the MEM Corliss
« Reply #19 on: November 09, 2020, 08:57:57 PM »
That is looking great - nice save on the spokes too!

Online JCvdW

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Re: JC attempts the MEM Corliss
« Reply #20 on: November 16, 2020, 12:46:21 PM »
With the Loctite set, I sawed off the spoke ends and then carefully turned the inner rim down until the outer rim could just slide on, up to the slight ridge left on the inside of the outer rim. I decided to use JB Weld slow setting epoxy to join the two rims. This allowed me ample time to carefully position the outer rim to run as true as possible with the inner in the four jaw chuck. I am quite pleased with the final result.




While waiting for the glue to set, I started thinking about the cylinder block, and read through Arnold's and Vince's build threads. Quite a lot of new challenges ahead. First of all getting the chunk of 60 x 60 mm mild steel down to 50 x 50 mm, then getting familiar with terms such as fly cutting, honing and/or lapping of the cylinder. And drilling and tapping lots of M2 and M3 holes. In anticipation of the latter, and seeing that the raw material is oversize, I carefully drilled a shallow 1mm hole with the milling machine to get a feel for what is possible.





Any general advice on any of the above will be much appreciated. I do have a spare block of raw material, just in case :LickLips:
« Last Edit: November 16, 2020, 12:49:59 PM by JCvdW »

Offline crueby

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Re: JC attempts the MEM Corliss
« Reply #21 on: November 16, 2020, 01:57:11 PM »
Terrific job on the flywheel, looking forward to seeing the cylinder shaping.

Offline vcutajar

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Re: JC attempts the MEM Corliss
« Reply #22 on: November 16, 2020, 03:41:50 PM »
It will end up looking like Swiss cheese - full of holes.  :D :D

Vince

Offline astroud

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Re: JC attempts the MEM Corliss
« Reply #23 on: November 16, 2020, 05:18:59 PM »
I cheated on my Corliss by boring out the block to just oversize then pushing in a thin brass tube liner. The finished bore was slightly undersize to drawing but it meant I did not have to worry too much about the surface finish during boring or having to hone it. The brass tube had a polished id quite acceptable for use with a piston using an O ring without any further work.
Of course you might be relishing the boring and honing challenge...

Andrew

Online JCvdW

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Re: JC attempts the MEM Corliss
« Reply #24 on: November 16, 2020, 07:31:59 PM »
Thanks for the encouragement crueby!

Andrew, the liner idea is interesting. Will keep it in mind as plan B. Would like to learn a bit about lapping though. I read Tug's thread on lapping today (http://www.modelenginemaker.com/index.php/topic,1908.0.html), and would like to try some of his techniques. Thanks Tug!

My power hacksaw, which I built as my first metal work project earlier this year during the lockdown, earned its keep today. It is based on plans I purchased online from myfordboy (https://myfordboy.blogspot.com/p/compact-power-hacksaw.html). Within 90 minutes, it reduced the 60 x 60 mm cylinder stock to 51 x51 mm. I was not sure if it will be up to the task. And I am really impressed with the bimetal hacksaw blade. It would easily cut another mild steel block down to size.



« Last Edit: November 16, 2020, 07:36:52 PM by JCvdW »

Online JCvdW

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Re: JC attempts the MEM Corliss
« Reply #25 on: December 05, 2020, 04:52:42 PM »
After some distractions I finally managed to complete the flywheel by boring out the axle hole to 9mm using one tip of a 5mm end mill.




I also turned the shaft, and with the flywheel off the four yaw chuck for the first time in a long while, I am quite pleased with the final result.


Offline Admiral_dk

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Re: JC attempts the MEM Corliss
« Reply #26 on: December 05, 2020, 07:04:10 PM »
Looks like you got it to run very true  :ThumbsUp:

Offline Dave Otto

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Re: JC attempts the MEM Corliss
« Reply #27 on: December 05, 2020, 07:23:44 PM »
Nice work on the flywheel!

Dave

Offline vcutajar

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Re: JC attempts the MEM Corliss
« Reply #28 on: December 05, 2020, 09:37:58 PM »
 :ThumbsUp: :ThumbsUp:

Vince

Online JCvdW

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Re: JC attempts the MEM Corliss
« Reply #29 on: December 09, 2020, 08:51:12 PM »
The 8mm HSS tool bit for the fly cutter arrived a few days ago. I watched the Youtube video 'Use of the fly cutter on the milling machine' by Tom's Techniques and studied his drawings on how to grind a tool bit for fly cutting. With my newly ground fly cutter, I squared up the cylinder block and brought width and height to final dimension. I left the length 2 mm too long, to be faced off later when boring the cylinder on the lathe. Quite happy with the result.



My newly acquired 2mm and 3mm taps and related drill bits are now waiting to turn this block of steel into a Swiss cheese ...