Author Topic: JC attempts the MEM Corliss (Read 3130 times)

JCvdW · « **on:** October 29, 2020, 09:47:59 AM »

Being inspired by the MEM Corliss steam engine build threads of Arnold (http://www.modelenginemaker.com/index.php/topic,1333.0.html), Vince (http://www.modelenginemaker.com/index.php/topic,1526.0.html), and others, I decided to give it a go.

I will be using the 24mm to 1 inch metric plans, found here: http://www.modelenginemaker.com/index.php/topic,1285.60.html

Thanks to everyone for all the relevant information available on this forum.

Being a novice, and this my first steam engine, this may end up being a bridge too far ...

I decided to start with the flywheel, and to construct it from separate parts for the rim, spokes and hub.
I ordered some hollow bar for the outer and inner rim. The closest sizes I could find were 180 x 150 mm and 170 x 140 mm.

The Myford Super 7 has a capacity of 178 mm, so I had the outer rim machined down to 176 mm by a local engineering shop. The outside had a very good finish, which I hoped I could use as is. I clocked it in as best I could on the four yaw chuck and started boring out all the excess material.

As the rim got closer to size, I noticed that the material had warped and that the outside was not running true anymore. By now the rim could fit over the chuck, so I remounted it and turned the outside to be circular again, removing 50 micron at a time. The tool just reaching the width of the rim.

Now to bore the inside to final dimension. I tried to grip the rim on the outside, but found that gripping on the inside results in less distortion of the rim. The best I could clock it to was about 100 micron, with as light a grip as possible. I bored out the inside from both sides taking off 50 micron at a time. I left the inside diameter on one side about 100 micron smaller to create a reference edge for the inner rim to fit against, as suggested by Arnold.

So after many more hours than I expected at the start, the outside rim is complete. Quite pleased with the final result.

Now for the hub and the inner rim. I already made an indexing plate that fits on the outside of the lathe spindle, to use when drilling the spoke holes.

Ramon · « **Reply #1 on:** October 29, 2020, 11:15:54 AM »

Hi JC,
as someone just coming to the end of a Corliss build here's to wishing you well with yours. The MEM design is a nice project and a fine runner - Good luck with your endeavors

Regards - Ramon aka 'Tug'

JCvdW · « **Reply #2 on:** October 30, 2020, 08:21:12 AM »

Quote from: Ramon on October 29, 2020, 11:15:54 AM

Hi JC,
as someone just coming to the end of a Corliss build here's to wishing you well with yours. The MEM design is a nice project and a fine runner - Good luck with your endeavors

Regards - Ramon aka 'Tug'

Hi Tug

Thank you very much. I had a quick look at the video of your tandem Corliss. Beautiful! Well done! Workmanship that I can only aspire to!

vcutajar · « **Reply #3 on:** October 30, 2020, 08:33:47 AM »

Good luck JC. I am sure you will enjoy the build. Pulling up a chair and some popcorn.

Vince

JCvdW · « **Reply #4 on:** October 30, 2020, 08:59:38 AM »

Started on the hub. Mounted my hand drill on the cross slide to drill the spoke holes. Clocked it in to be perpendicular to the hub.

Setting the height of the drill, using an old drill bit with tip ground to a point.

Tapping the eight M6 spoke holes with a spring loaded tap holder in the chuck.

All spoke holes done. I took Arnold's idea and also drilled and tapped M4 holes for two grub screws to secure the flywheel to the crankshaft. Shaft hole drilled 1mm undersize, to be accurately bored later once the flywheel is assembled.

Hub complete.

JCvdW · « **Reply #5 on:** October 30, 2020, 09:01:36 AM »

Quote from: vcutajar on October 30, 2020, 08:33:47 AM

Good luck JC. I am sure you will enjoy the build. Pulling up a chair and some popcorn.

Vince

Thank you Vince. You are one of the reasons why I decided to give this a go.

Kim · « **Reply #6 on:** October 30, 2020, 08:01:36 PM »

Hmm... JC, for some reason I'm not seeing your pictures. Is anyone else having this problem? Or is it something specific on my end?

Kim

crueby · « **Reply #7 on:** October 30, 2020, 08:22:49 PM »

Quote from: Kim on October 30, 2020, 08:01:36 PM

Hmm... JC, for some reason I'm not seeing your pictures. Is anyone else having this problem? Or is it something specific on my end?

Kim

Not seeing the pictures here either.

vcutajar · « **Reply #8 on:** October 30, 2020, 09:16:24 PM »

The photos were visible this morning but not now.

Vince

Ramon · « **Reply #9 on:** October 30, 2020, 10:06:46 PM »

Haven't seen any images so far - logged in or out

Tug

Kim · « **Reply #10 on:** October 30, 2020, 11:00:03 PM »

Hi JC,
Sorry about the photo problems

I'm betting that it's a permissions issue with wherever you have them hosted. When you upload the pictures, you're logged in, so you can access them and see them in your posts. But nobody else is logged into your account, so we can't see them.

There's probably a way to change the permissions on the photos to allow other people access. I don't know what service you're using, so I can't give you more specific info. But I'm guessing if you poke around in permissions you'll come up with something.

Good luck!
Kim

JCvdW · « **Reply #11 on:** October 31, 2020, 08:39:55 AM »

Kim & Tug, thanks for the feedback re the photos.

Turns out that the photo links I used were not permanent, and as far as I can tell, permanent links are not available for ICloud images. I am now using Imgur to host the images, and direct permanent links to the images are immediately shown.

Ramon · « **Reply #12 on:** October 31, 2020, 10:40:38 AM »

That's much better JC - good photos too. Looks like you've made a good start

Tug

Kim · « **Reply #13 on:** October 31, 2020, 04:32:55 PM »

Thanks JC,

Yes, I see your pictures now! Thanks for taking the time to re-post them.

Looks like you're making good progress on your flywheel!
Kim

Johnmcc69 · « **Reply #14 on:** November 01, 2020, 01:32:40 AM »

Nice job! I especially like the cross-drilling set up.

John

crueby · « **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!

JCvdW · « **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.

Ramon · « **Reply #17 on:** November 09, 2020, 01:14:41 PM »

That's a good start JC, looks very promising

Keep it coming

Tug

JCvdW · « **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.

crueby · « **Reply #19 on:** November 09, 2020, 08:57:57 PM »

That is looking great - nice save on the spokes too!

JCvdW · « **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

crueby · « **Reply #21 on:** November 16, 2020, 01:57:11 PM »

Terrific job on the flywheel, looking forward to seeing the cylinder shaping.

vcutajar · « **Reply #22 on:** November 16, 2020, 03:41:50 PM »

It will end up looking like Swiss cheese - full of holes.

Vince

astroud · « **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

JCvdW · « **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.

JCvdW · « **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.

Admiral_dk · « **Reply #26 on:** December 05, 2020, 07:04:10 PM »

Looks like you got it to run very true

Dave Otto · « **Reply #27 on:** December 05, 2020, 07:23:44 PM »

Nice work on the flywheel!

Dave

vcutajar · « **Reply #28 on:** December 05, 2020, 09:37:58 PM »

Vince

JCvdW · « **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 ...

crueby · « **Reply #30 on:** December 09, 2020, 11:44:30 PM »

Got an excellent finish with the fly cutter!

JCvdW · « **Reply #31 on:** January 03, 2021, 08:39:43 AM »

After a bout of Covid 19, it was time to do something in the workshop again. I decided to bore the cylinder. Up till now I had better results on the lathe with HSS tool bits compared to carbide inserts. So I had to make a HSS boring bar. I like the boring bars made by Stefan Gotteswinter (https://youtu.be/O9d_I0A4kzg), so I first had to make a tool to make a tool - a slitting saw arbour (also according to a design by Stefan) to cut a slit for the boring bar.

Unfortunately I only had 10mm round stock for the bar, and all the suppliers are closed for the summer break. Would have preferred it a bit thicker.

After facing the cylinder block on the lathe, I drilled out the cylinder to the maximum diameter drill I have, and then started boring with a carbide insert (lots of chatter) until the hole was big enough to accept my brand new boring bar with its freshly ground 4mm HHS bit.

Roughing out went smoothly, my boring bar is working! No chatter. As I approached the final dimension, I rounded the tool bit a little bit with a stone, reduced the depth of cut, and decreased the feed rate, expecting a very smooth surface finish as the result. Big mistake! Steep learning curve! The tool immediately started to chatter. Being close to final dimension, I had to stop boring. Should have started experimenting earlier! Due to the small depth of cut, the chatter marks are relative small though. I am now curious to see if lapping will remove the chatter marks and leave a smooth finish. As soon as I can find a 3mm sheet of copper I will attempt lapping by following Tug's thread http://www.modelenginemaker.com/index.php/topic,1908.0.html.

But before lapping, I first have to drill the inlet and exhaust holes.

JCvdW · « **Reply #32 on:** January 03, 2021, 09:24:43 AM »

I decided to follow Vince's approach to drill the port holes. But first another tool had to be made - a lathe stop. I followed Joe Pieczynski's design (https://youtu.be/LrCS_-3Gh0Y). I also made a 15 deg reference plate for the vice, and then proceeded to mill 3mm flats for the drill bit to start on.

Then it was time for the first 1.5mm hole. I spot drilled with a 90deg spot drill, held my breath and started drilling. At about 8mm depth, the drill broke.

This is not going to work. The maximum speed of my mill (Rong Fu 45 clone) is only 1600 RPM, the total runout is about 30 micron, and of course there is no feel for what the drill bit is doing. And the required depth of a hole is more than 12 mm.

So what to do? At this point I think it will be better to first drill the valve holes, mill the steam pockets, and only then drill the small holes, which then only has a depth of about 2mm. I am also contemplating to buy or make a micro drill adapter which allows feeding the drill by hand while still being driven by the mill, as demonstrated here (https://youtu.be/PqU5wS0J4MU). Another alternative would be to use my home made CNC router (which has so far only been used for milling wood). It has a variable spindle speed from 5000 to 20000 RPM.

I do not think it will be possible to remove the broken drill bit. On the bright side - at least now I have a cylinder block to try out different drilling strategies, and also practise lapping.

Any advice will be much appreciated.

Ramon · « **Reply #33 on:** January 03, 2021, 09:54:38 AM »

Hi JC,

Commiserations on that broken drill - not the best place to be at any time. Still it looks recoverable.

My thoughts would be to forget the broken drill and use a slightly larger drill to do the remaining holes within the limits of the slot - 2 -2.2mm maybe and drill slowly (feed) at your max revs. 1600 rpm may not be text book but should be more than sufficient. Lots of small pecks and withdrawal to clear the swarf is needed on this situation. It doesn't take much swarf to jam a small drill and that's a deep hole relevant to diameter. Keeping the swarf clear is something to keep in mind at all times here

You could use a carbide drill to try to remove the broken one but given where it is and the little effect it will have on the final running personally I wouldn't bother - you could end up making things worse which is always a risk. Increasing the diameter of the holes will easily make up for any loss of flow. Annoying to think it's there though but once covered - 'out of sight out of mind' soon makes it forgotten about

Your mill looks very similar to my Amadeal so I assume you have a drill spindle function. It has to be said that mine is 'heavy' in feel compared to my drill which does affect feel on using small drills but with care this op should be manageable as set up.

Hope that's not teaching granny etc -

Good luck with it - and that lapping

Tug

astroud · « **Reply #34 on:** January 03, 2021, 11:22:25 AM »

I drilled out the valve holes and milled the valve chambers before drilling the valve passages. However it was still a fraught operation as the drill then starts on the curved surface of the valve hole and starts to dance unless extreme care is taken. A very light touch is needed to allow the drill to centre.

JCvdW · « **Reply #35 on:** January 07, 2021, 09:03:19 AM »

Tug:
Thanks for the feedback. It made me realise that the cylinder block is not lost, and I should be able to recover from the broken drill bit. I also realised that it should still be possible to dislodge the broken bit when machining the steam pocket.

astroud:
Thanks for the info. I will never have a light touch with my milling machine. I therefor decided to order a sensitive drill attachment from LittleMachineShop in the USA, which allows one to feed the drill by hand. Hope this will solve my problem. It is just frustrating that none of these more specialised tools are available in South Africa.

In the mean time I found some 2mm copper sheet at the local scrap yard, and made a cylinder lapping tool. Thanks again for your info Tug! I am not familiar with silver soldering, so I glued the copper tube to the leading edge of the D-section using two part epoxy. This is working well.

I could not resist trying out the lapping tool even before for the steam ports have been drilled. I used some fine automative grinding paste, and the chatter marks quickly disappeared. I followed this with some polishing compound that I happen to have in the workshop. The cylinder is not perfect yet, but much better than before. As far as I can tell with my telescoping inside micrometer, the bore is as parallel as I can measure.

Ramon · « **Reply #36 on:** January 08, 2021, 09:53:22 PM »

Nice work on the lapping JC

good to note that epoxy did the trick too. Silver soldering is always a bit fraught in case it runs to far.

Keep it coming

Tug

JCvdW · « **Reply #37 on:** January 19, 2021, 07:29:53 PM »

Thanks for the encouragement Tug!

While waiting for the sensitive drill attachment to arrive, I made the outrigger bearing pedestal. I treated myself to a rotary table for Christmas and thought the round corners of the pedestal base to be a good opportunity to try out my new toy. I mounted the four yaw chuck on the rotary table to hold the part.

Unfortunately, the corner radii came out too large, so I will have to remake the part. It never the less turned out to be a good practice run with the rotary table and also to practice some filing and sanding to remove machining marks from a milled part. Next time I will machine the corners first, while the part is much more sturdy to clamp in the rotary table. I will also use some shim stock packing to prevent clamping marks.

JCvdW · « **Reply #38 on:** January 19, 2021, 07:46:05 PM »

The sensitive drill attachment arrived today. Made in China, imported from the USA... There is quite a bit of play in the sliding mechanism, so I was a bit sceptical at first. After successfully drilling ten 1.5mm holes through a 10mm piece of scrap mild steel, I however feel much more confident to drill the cylinder block. One directly feels what the drill is doing. If the drill bit gets stuck as it breaks through, it simply spins in the small chuck, without breaking.

Ramon · « **Reply #39 on:** January 19, 2021, 08:45:51 PM »

Hi JC,

Something that did occur to me and perhaps worth mentioning before you have another go at drilling the cylinder.

Did you just centre drill on an angled surface with cylinder set at the angle or did you create a flat bottom square to the drill before centre drilling. If the surface was at an angle, despite being centre drilled that can kick a drill off - it would be best to plunge a small cutter in to bring the surface level to the drilling direction before centre drilling.

Good luck with it

Tug

crueby · « **Reply #40 on:** January 19, 2021, 09:44:08 PM »

JC, how does the sensitive drill attachment work - is there a clutch in it, or are you adding pressure with that ring?

JCvdW · « **Reply #41 on:** January 20, 2021, 10:18:51 AM »

Quote from: crueby on January 19, 2021, 09:44:08 PM

JC, how does the sensitive drill attachment work - is there a clutch in it, or are you adding pressure with that ring?

The attachment has a spring loaded telescopic shaft to drive the chuck from the mill. The external ring is attached to the movable shaft with a bearing. One holds the external ring by hand to apply down force on drill bit. Total available downward movement is about 24 mm.

JCvdW · « **Reply #42 on:** February 08, 2021, 08:40:32 PM »

Tug, thanks for the suggestion. I did mill a flat surface in the cylinder block with a 3mm end mill before drilling.

Working on the bearing pedestal made me realise that I need more practice on the mill before taking on the more complex parts. So I postponed further work on the cylinder block for a while.

I had another go at the bearing pedestal, with a much more satisfying end result. A coat of primer, and it is ready for storage. I never expected making these parts will take so long, so it will probably remain in storage for quite a while ...

JCvdW · « **Reply #43 on:** February 08, 2021, 08:57:12 PM »

I decided to make the cylinder feet next. Relatively simple parts to gain more experience with the mill. I have realised by now that starting out with correctly dimensioned and squared stock, makes life much easier further down the line. It also became apparent that I can do with a set of parallels for the vice, rather than the piece of steel ruler that I am currently using.

I went for the split design of the feet, for easier assembly later.

A coat of primer will hide any minor remaining machining marks, so I am happy with the feet so far.

JCvdW · « **Reply #44 on:** February 26, 2021, 03:24:56 PM »

I finally finished the two cylinder feet. I keep on surprising myself with how easy it is to make a silly mistake. I drilled one of the feet mounting holes too big. Rather than remaking the part (for the third time!) I made a plug and Loctite it into the oversize hole.

A coat of primer to keep the rust away, and the feet are ready for future assembly.

JCvdW · « **Reply #45 on:** February 26, 2021, 03:37:40 PM »

Started on the two bearing blocks for the flywheel. I decided to machine both bearings together from a single block of bronze which I had cut from a piece of round bar. I will later separate the two bearings with a slitting saw.

I bored the axle hole on the lathe using a long 5mm end mill as boring bar. I also faced it off to have one side of the block perpendicular to the hole. The axle in the hole then served as reference to machine the base of the bearings parallel to the axle.

I now have to create the curved top of the bearing...

JCvdW · « **Reply #46 on:** February 27, 2021, 06:28:05 PM »

I shimmed the top edges of the milling chuck with the blade of a feeler gauge and then milled the curved top of the bearings by rolling the bearing block on the axle.

Using a Magnifying Glass application on my mobile phone, I could accurately position the cutter to mill right into the corners of the curve.

After some further sanding with home made sanding sticks, I am quite happy with the result so far.

crueby · « **Reply #47 on:** February 27, 2021, 06:31:24 PM »

great work!

Johnmcc69 · « **Reply #48 on:** February 28, 2021, 04:37:05 PM »

That did turn out nice!
Cool idea about the "Magnifying Glass"!

John

JCvdW · « **Reply #49 on:** March 05, 2021, 02:26:58 PM »

Thanks John en crueby for the kind remarks!

After drilling the mounting holes, I split the two bearings with a slitting saw, and machined to size.

Now for the Crankshaft Support to mount the second bearing ...

JCvdW · « **Reply #50 on:** March 05, 2021, 02:36:04 PM »

I started making the Crankshaft Support by machining the rounded corner. Not having a cutter for this, I used a ball nose cutter the same way a CNC machine would do. I calculated the incremental X and Z coordinates that will result in a rounded corner. It certainly worked better than trying to round the corner with a file.

JCvdW · « **Reply #51 on:** March 06, 2021, 04:44:49 PM »

Finished machining the Crankshaft support today. Motivating to see the first bit of a subassembly!

vcutajar · « **Reply #52 on:** March 06, 2021, 04:48:51 PM »

Nice.
Starting to take shape.

Vince

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Author Topic: JC attempts the MEM Corliss (Read 3130 times)