Author Topic: MEM Corliss build Flywheel  (Read 3212 times)

Offline JasonP

  • Full Member
  • ****
  • Posts: 25
MEM Corliss build Flywheel
« on: January 02, 2023, 10:18:01 PM »
My build of the Mem Corliss is very slowly progressing. While I had some time over the holidays I thought I would start thinking about the flywheel. I have a problem. The OD of the flywheel is 7.25" and I've only got a Mini-lathe with a 7" swing. Being a Mini-lathe, that's not even usable swing as I can't get tooling onto the outer rim at anything like that diameter.

So I'm trying to think about alternatives. The planes show a fabricated flywheel, which I guess is a possibility, except the outer rim and inner rim are a press fit together. Where can I source those parts ready made? I can drill the spoke holes, just can't turn the inner rim to a press fit diameter.

Anyone in the US made one of these on a Mini-lathe? Any suggestions?

Thanks,

Jason

Offline wagnmkr

  • Full Member
  • ****
  • Posts: 915
  • Lindsay, Ontario, Canada
Re: MEM Corliss build Flywheel
« Reply #1 on: January 02, 2023, 10:38:47 PM »
What mini lathe are you using, and can you get / make a set of risers for it?
I was cut out to be rich ... but ... I was sewn up all wrong!

Offline crueby

  • Full Member
  • *****
  • Posts: 18559
  • Rochester NY
Re: MEM Corliss build Flywheel
« Reply #2 on: January 02, 2023, 10:55:04 PM »
To make it fit the lathe you have, reducing the diameter of the flywheel to 7 or just under is always an option.

Online steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: MEM Corliss build Flywheel
« Reply #3 on: January 02, 2023, 11:08:34 PM »
Got a picture?

Here's a common way around maximum swing.     Using a boring bar that's been reversed and reach around the OD...  ( I know this is NOT a 7" lathe, but it illustrates the method)

That way you can reach without having to run the saddle under the part.    Rigidity will suffer, but it's a way forward.    Did I mention we need pictures? 8)

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline RReid

  • Full Member
  • ****
  • Posts: 1668
  • Northern California
Re: MEM Corliss build Flywheel
« Reply #4 on: January 03, 2023, 01:03:41 AM »
I've used the basic technique mentioned by Steamer several times to turn flywheels on my Taig lathe which were just barely clearing the bed. You needn't worry about reducing the diameter of the flywheel a bit to fit on your lathe either, the difference between 7" and 7.25" is trivial.
Regards,
Ron

Offline Jasonb

  • Full Member
  • *****
  • Posts: 9467
  • Surrey, UK
Re: MEM Corliss build Flywheel
« Reply #5 on: January 03, 2023, 07:07:00 AM »
If you do use a standard right hand boring bar don't forget to run the lathe backwards when using it  ;)

If it's an insert boring bar then stick an insert intended for aluminium in it which will cut better at those diameters as they are sharper than the standard ferrous inserts.

<a href="https://www.youtube.com/watch?v=3YZ0mKAzMgE" target="_blank">http://www.youtube.com/watch?v=3YZ0mKAzMgE</a>

Offline pgp001

  • Full Member
  • ****
  • Posts: 812
  • West Yorkshire - UK
Re: MEM Corliss build Flywheel
« Reply #6 on: January 03, 2023, 07:55:35 AM »
Here's what I did.

Note the use of lead weights to dampen out any vibration.




Offline JasonP

  • Full Member
  • ****
  • Posts: 25
Re: MEM Corliss build Flywheel
« Reply #7 on: January 03, 2023, 07:19:34 PM »
Look at all you chaps with your big lathes!

When I said it's a 7" swing, I meant 7" swing over the bed, so 3 1/2" radius. I cannot physically fit a 7" round piece of stock. I can (and have) used the boring bar method on large diameter parts and yes, rigidity sucks.

The biggest I can turn would be 6.9", but in reality it's 6.5" as that's the size of stock I can get, which is getting a little small for the scale of the engine (I may be over thinking that).

Option A is to machine the flywheel out of a single piece with a max OD of 6.5"
Option B is to fabricate a 7.25" flywheel, but I don't have a source for the stock and machining the inner rim to a press fit could be out of my capabilities. The inner rim is 6.875" and getting it to press fit dimension  :thinking:



Offline Jasonb

  • Full Member
  • *****
  • Posts: 9467
  • Surrey, UK
Re: MEM Corliss build Flywheel
« Reply #8 on: January 03, 2023, 07:34:11 PM »
We are also all showing proportionally larger flywheels. These were to illustrate the method of turning not to show off teh size of our machines, the method applies to any lathe being pushed to it's limits. We were showing you that you can get tooling onto the rim which you said you can't

Someone in the US would be best pointing you to materials but over here we can get 168mm OD thick wall tube which would be about right for a minilathe version if you want to machine the "Tee" from solid.


Offline vtsteam

  • Full Member
  • ****
  • Posts: 753
Re: MEM Corliss build Flywheel
« Reply #9 on: January 03, 2023, 07:36:11 PM »
What material is the flywheel going to be made from?
Steve

Offline vtsteam

  • Full Member
  • ****
  • Posts: 753
Re: MEM Corliss build Flywheel
« Reply #10 on: January 03, 2023, 08:05:30 PM »
If cast iron, grab a tape measure, and pay a visit to your local friendly auto mechanic, explain your situation, and ask if you can have a discarded brake disk rotor, assuming it's the right size. The hubs are generally in the range of 6" - 7-1/2", though the rims are larger. Cut off the rim with a hand grinder cutoff disk.

I think wagnmkr's suggestion of making a temporary 1/2" riser block for your headstock is a good one if you can't find a rotor hub under 7" and above 6.5".
Steve

Offline TerryWerm

  • Full Member
  • ****
  • Posts: 126
  • Jordan, MN - 6147 nice folks and one grouch!
Re: MEM Corliss build Flywheel
« Reply #11 on: January 03, 2023, 08:54:20 PM »
Maybe this idea is wacko, but what would be wrong with making a flywheel of a workable diameter (6.5") but redesigning it a bit to give it a heavier rim? Might even have to make it a bit wider as well as thicker so that it looks proper, but I would think that it would work.
----------------------------
Terry
Making chips when I can!

Offline pgp001

  • Full Member
  • ****
  • Posts: 812
  • West Yorkshire - UK
Re: MEM Corliss build Flywheel
« Reply #12 on: January 03, 2023, 10:27:51 PM »
If you have a milling machine with enough capacity, that can be pressed into service to machine the outside of a flywheel using a rotary table.
You will not get the same finish as on a lathe, but when needs must..........

Phil

Offline MJM460

  • Full Member
  • ****
  • Posts: 1647
  • Melbourne, Australia
Re: MEM Corliss build Flywheel
« Reply #13 on: January 03, 2023, 10:58:40 PM »
Hi Terry, not a wacko idea at all.  You are on the right track by suggesting a heavier rim on a smaller OD, as it’s the moment of inertia of the fly wheel, not it’s mass that is important.  Mass located at a larger radius from the axis of rotation has a greater effect than mass close to the axis.  The calculations are relatively simple and I can help with the formulae if required.

Hi Jason, the other thing to remember is that for a double acting engine like the Corliss, the flywheel only has to get it past the dead centres without stopping.  Once this is achieved, further increase in flywheel inertia simply reduces the speed variation.  Of course this is more important when slow rotation is required, most model engine flywheels are much larger than the minimum required.

If you do not feel up to the solutions already suggested to get around your lathe size limitations, make the flywheel from the largest practical diameter, based on your tooling and available materials.  Your engine will run fine with that, providing all the other more critical issues are correct.

I suspect that most flywheels on models are sized on “looks about right” basis, which of course becomes a self fulfilling expectation of what looks right.  And of course, for a scale prototype the proportions of the original are more important.

MJM460

The more I learn, the more I find that I still have to learn!

Offline Jasonb

  • Full Member
  • *****
  • Posts: 9467
  • Surrey, UK
Re: MEM Corliss build Flywheel
« Reply #14 on: January 04, 2023, 07:05:52 AM »
As the OP mentions going down to 6.5" will affect the look of the engine. These engines typically had a fairly thin but wide flywheel rim section and at 1.5" wide already would start to look wrong if made much wider or too thick. If you look at the MEM logo at the top of the page that is the sort of thing that looks right.

If the 6.5" option were used then the best place to increase the weight without spoiling the look would be to have a thicker leg to the "T" where the spokes join. You can buy 6.5" OD DOM Tube with suitable wall thickness

Looking at Speedy metals I can't see much in the way of thin walled tube that could be slipped over a 6.5" centre section but if anyone in the US knows of a source of short lengths of 7" OD x 1/4" wall DOM type tube then that could be bonded to a ring of 6.5OD material to form a "T" section

Online steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: MEM Corliss build Flywheel
« Reply #15 on: January 04, 2023, 12:31:04 PM »
I'm over here in the US.  I'm waiting for the OP to get back to us about the suggestions so far.
When Maryak laid that design down   He intended it to be a starting point for a new Model Engineer.   I dare say many things could be modified including the diameter of the flywheel.    In this case that person needs to decide for themselves but I'm glad to support them with that decision making process.    Bob would have wanted the forum to help

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 7863
  • Portland, Oregon, USA
Re: MEM Corliss build Flywheel
« Reply #16 on: January 04, 2023, 06:40:45 PM »
I just found some 7", 1/4" wall DOM tube at Speedy Metals for $26.40 per inch (on sale now for $21.12 per inch).

https://www.speedymetals.com/p-3619-7-od-x-250-wall-dom-steel-tube.aspx

Don't know if this is a reasonable price.  Certainly not what I'd call cheap, but I haven't been pricing 7" DOM tube lately.

Kim

Offline TerryWerm

  • Full Member
  • ****
  • Posts: 126
  • Jordan, MN - 6147 nice folks and one grouch!
Re: MEM Corliss build Flywheel
« Reply #17 on: January 07, 2023, 08:56:55 PM »
Hi Terry, not a wacko idea at all.  You are on the right track by suggesting a heavier rim on a smaller OD, as it’s the moment of inertia of the fly wheel, not it’s mass that is important.  Mass located at a larger radius from the axis of rotation has a greater effect than mass close to the axis.  The calculations are relatively simple and I can help with the formulae if required.

An overview of the formula and process to select the proper dimensions would be an interesting thread subject in general and would not have to be specific to any particular flywheel or engine. It would make a great reference thread! I have no idea what the formula would be, but it would be an interesting subject.
----------------------------
Terry
Making chips when I can!

Offline MJM460

  • Full Member
  • ****
  • Posts: 1647
  • Melbourne, Australia
Re: MEM Corliss build Flywheel
« Reply #18 on: January 08, 2023, 01:19:05 AM »
Thanks Terry,

I will assume others will be thinking along similar lines and will put something together.  I will start a thread as you suggest in the next week or two.

The calculations are not hard with the right formula, and the principle of looking at moment of inertia for rotational motion compared with mass for linear motion that is important.  I will try and make it clear.

MJM460

The more I learn, the more I find that I still have to learn!

Offline TerryWerm

  • Full Member
  • ****
  • Posts: 126
  • Jordan, MN - 6147 nice folks and one grouch!
Re: MEM Corliss build Flywheel
« Reply #19 on: January 08, 2023, 03:11:09 AM »
Thank you MJM!!  I will be looking forward to it. Gotta learn new stuff all the time!
----------------------------
Terry
Making chips when I can!

Offline JasonP

  • Full Member
  • ****
  • Posts: 25
Re: MEM Corliss build Flywheel
« Reply #20 on: January 08, 2023, 04:30:57 PM »
Some very helpful hints and tip, thanks guys. I didn't think of adding a standoff to my headstock, which is an option that I'll keep in the file for later.
I did try mounting the stock on my 4" rotary table, and milling the OD down, but I couldn't get it rigid enough. I persevered until I trashed my favourite 1/2" end mill  :censored:

My new solution was to phone a friend. He has a fab shop and could let me have a an offcut of 7.5" steel 1018 (I think) bar, about 3" thick. He also has an old LeBlond lathe that I can use to rough out the stock. I chucked it up in the 4 jaw, hogged it down to 6.9" and 1.5" wide, cutting a boss in one face so I can hold it on my mini-lathe. On the other side I left a 3/4 stem.
Pain in ass to do it with the big 4 jaw. My buddy has very few tools and only uses this lathe for one operation in his shop. No dial test indicators or any way to dial the 4 jaw in, so I knew this was going to be really rough. He has some carbide tooling, but the power cross feed wasn't working on his lathe and it was stuck at one speed that was too slow for carbide. The results was really rough and I'm not proud, but it got the job done.
 
I got the part on my lathe and turned the stem to 1/2". I also cleaned up the really nasty face and turned the O.D. down to 6.75" I got a really nice finish on the OD after I mounted the stem in a collet chuck. The flywheel is nicely balanced now and runs smooth in the lathe with no vibration.

I still have a lot of work to do, but the plan is to shape the flywheel on the lathe, then mill out the spokes. The final dimensions should be 6.75 x 1.375, so a bit smaller and wider than the plans, but it should work out. There will be a lot of lathe hours in this flywheel by the time it's done, and I'll probably go though a lot of carbide inserts. It's just too big to try my larger cutters, so I'll be nibbling away with 15-20 thou depth of cut with smaller tooling and lots of passes. Given the size of the flywheel, I have to reposition the QCTP to be able to get to the entire face so I can't even machine it in one pass. The joys of a mini-lathe.

MJM - Would love to see the calcs on this. I've ballparked the flywheel size and it's certainly going to have enough inertia!

Steamer - I appreciate the support. I think an awful lot of newcomers to this world will start with the 7" Chinese mini-lathe. The Corliss is pushing my 7" x 12" to the limit, but it's fun figuring it out. The s50 and 10v I built before were easy compared to this  :)


Offline Admiral_dk

  • Full Member
  • *****
  • Posts: 3752
  • Søften - Denmark
Re: MEM Corliss build Flywheel
« Reply #21 on: January 08, 2023, 07:33:28 PM »
Looks a lot better after cleaning up on your own Lathe  :ThumbsUp:

Per

Online steamer

  • Global Moderator
  • Full Member
  • *****
  • Posts: 12697
  • Central Massachusetts, USA
Re: MEM Corliss build Flywheel
« Reply #22 on: January 08, 2023, 07:41:01 PM »
Looks a lot better after cleaning up on your own Lathe  :ThumbsUp:

Per

Nah    Chips are sexy!  8)

Keep at it Jason....it's getting there
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Admiral_dk

  • Full Member
  • *****
  • Posts: 3752
  • Søften - Denmark
Re: MEM Corliss build Flywheel
« Reply #23 on: January 08, 2023, 07:55:46 PM »
I meant the Flywheel ..... anything else I missed  :headscratch:

Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 7863
  • Portland, Oregon, USA
Re: MEM Corliss build Flywheel
« Reply #24 on: January 08, 2023, 08:40:12 PM »
Boy, you weren't kidding that it was rough!  But it cleaned up nicely on your mini-lathe for sure.  :ThumbsUp: :popcorn:

Kim

Offline JasonP

  • Full Member
  • ****
  • Posts: 25
Re: MEM Corliss build Flywheel
« Reply #25 on: April 02, 2023, 09:59:57 PM »
Finally finished turning this sucker! It was a beast on my little lathe. Final OD 6 11/16"  width 1 3/8". Smaller than I intended, but after killing a lot of carbide and blowing a controller this is what I've taken off the lathe. It runs concentric to the crankshaft, which is no mean feat when using a lathe as rigid as chocolate pudding.


Next step is to mill out the spokes. Someone had an excel spreadsheet to assist with that, I need to hunt it down.


Offline crueby

  • Full Member
  • *****
  • Posts: 18559
  • Rochester NY
Re: MEM Corliss build Flywheel
« Reply #26 on: April 02, 2023, 10:07:19 PM »
Pretty sure that was Don1966 that posted the spreadsheet about spokes, search on his threads...

Offline JasonP

  • Full Member
  • ****
  • Posts: 25
Re: MEM Corliss build Flywheel
« Reply #27 on: April 02, 2023, 10:54:14 PM »
Yep, I  found his, also Todds software. Has anyone used the software? I put numbers in and got odd results, probably because I'm not familiar with the nomenclature.



Offline JasonP

  • Full Member
  • ****
  • Posts: 25
Re: MEM Corliss build Flywheel
« Reply #28 on: April 22, 2023, 07:24:56 PM »
In the end i used Todds software and the Excell sheet in combination to model the flywheel in Alibre, then printed those drawings and used Todds order of operations to mill it out.
Got the flywheel mounted on the rotary table, centered and securely fixtured. Then worked my way around milling it all out with 1/4" 3 flute endmill that worked well, although the surface finish is a bit rough.
The final result needs fettling with files and I'm thinking of trying to round the edges of the spokes with a rounding endmill, but it's mostly there. It should paint up nicely.

Offline vcutajar

  • Full Member
  • *****
  • Posts: 2555
  • Marsascala, MALTA
Re: MEM Corliss build Flywheel
« Reply #29 on: April 22, 2023, 09:11:40 PM »
Been there and done that.
Lots of work on the flywheel but very satisfying seeing the end result.

Vince

Online Kim

  • Global Moderator
  • Full Member
  • *****
  • Posts: 7863
  • Portland, Oregon, USA
Re: MEM Corliss build Flywheel
« Reply #30 on: April 23, 2023, 12:45:09 AM »
Beautiful flywheel!   :ThumbsUp: :popcorn:

That is a LOT of work milling out the flywheel spokes like that.  You did a great job of it!
Kim

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal