Author Topic: Making a flywheel from scratch - revisited  (Read 5777 times)

Offline gunna

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Making a flywheel from scratch - revisited
« on: April 05, 2014, 09:13:32 AM »
      A couple of years ago, John, aka Bogstandard, wrote an excellent post on this subject, see http://www.modelenginemaker.com/index.php?topic=1150.0 . I was especially intrigued by the taper lock hub he detailed and decided that I had to try it. However, there were a couple of major changes to be made to his methods.

     Firstly, for no particular reason, I wanted a flywheel made from cast iron. This raises a few problems with the supply of raw material, as it meant finding something which could be turned into a flywheel with, hopefully, not too much work.

     Secondly, after reading through most of the active posts here, I have to admit that I appear to be the only member of this forum without a milling machine.  :'(

     So the search for raw material became an ongoing thing, when, one day I was idly scanning through the junk mail and came across a brochure from a sports store. What caught my eye was the barbells. Here are a range of weights which are probably cast iron, already round in shape, and generally quite cheap. A bit of research showed that the smallest is about 160mm or a bit over 6 inches in diameter and was going to cost me the princely sum of $4!
     A possible drawback is the fact that they have a hole of about 28mm through the centre and the actual material may be absolute crap. Since John's taper lock mechanism used an inserted hub anyway, I thought the big hole would not be too much of a problem. The material quality was an unknown. Anyway, a quick trip down the street produced this:


     To save a lot of intermittent cutting, I took off all the lumps and bumps with an angle grinder:


     I then mounted the weight in the reversed jaws of the 3 jaw chuck and checked where the centre hole decided to run. Even though the outer rim was only the cast surface, the hole ran reasonably true, so I bored it out enough to clean up, and then faced the whole side, reducing the diameter of the central hub while I was at it. It was flipped over and the other side faced as well:


     A paper template of the desired result had been drawn up with all the important corner holes marked:


     This was cut out and attached with double sided tape so that the holes could all be centre punched. This also allowed me to locate some "waste ground" where I drilled three holes to attach the blank to the faceplate. With a backing of MDF I was able to turn the outer rim after the centre hole was set to run true:


     After all the reference holes were drilled, I marked out the spokes using the edges of the holes as markers. To remove the unwanted material, I chain-drilled around the perimeter and knocked out the waste:


     A couple of hours later, after the use of some coarse and fine files, and some coarse words, I had this:


     It was now time to make the hub assembly which would be of steel. The outer part was to be about 20mm long but was being turned on the end of a longer piece of stock which would be kept in the lathe until both the inner taper and outer diameter were finished to ensure concentricity. This meant boring a blind tapered hole which was smallest at the outer end. A hole 2mm larger than the intended shaft size was drilled in for about 30mm. The topslide (compound slide?) was set over to about 3 degrees and a small boring tool was inserted into the hole to a depth of 25mm. The scale was zeroed at this point as this depth would allow cutting the piece off later. All the boring had to be done by ear alone so the tool was slowly moved towards me until it started cutting. By moving the tool back and forth with the topslide while increasing the cut each pass, I reached the point where the tool was just cutting at the entrance of the hole. This was considered to be the end point of this operation. The outer diameter was simply turned to be a neat sliding fit in the wheel as it would be Loctited later. The inner piece was drilled and reamed to the shaft size while the outer was turned to the same taper as the topslide had not been moved, then slit with a junior hacksaw which leaves a very narrow cut. Here are the pieces:


     After assembling the hub, I fitted it to a piece of shaft and used this to get the wheel running true in the lathe again. A very thin shave was taken off the outer faces in order to true up the slight wobble that had appeared. This is how it looks now:


     While all this was going on, I thought that a flywheel like this needs a flywheel governor. I gathered up the waste pieces and found two that could be made into suitable shapes:


     My proposal for the governor is something like this when I work out where the springs go:


     So that's all folks, thanks for looking in.

Ian.

Offline PStechPaul

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Re: Making a flywheel from scratch - revisited
« Reply #1 on: April 05, 2014, 09:22:13 AM »
Nice looking flywheel! I've learned to look everywhere for materials that might be repurposed like this. I would probably not have bothered making the spokes, as more material just provides more inertia, but it does look good with spokes.  :ThumbsUp:

Offline peatoluser

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Re: Making a flywheel from scratch - revisited
« Reply #2 on: April 05, 2014, 10:48:10 AM »
 "after the use of some coarse and fine files, and some coarse words, "  :lolb:
as a lathe only workshop  I know what you mean!
I'm glad you didn't find any chilled spots in the C.I.
A very elegant flywheel by the way. I particularly like the tapered spokes

peter

Offline Roger B

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Re: Making a flywheel from scratch - revisited
« Reply #3 on: April 05, 2014, 11:05:21 AM »
Nicely done  :praise2:

I was also milling machine free until last month and I think there are a few others on here still using a vertical slide on the lathe when they have to mill.
Best regards

Roger

Offline zeeprogrammer

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Re: Making a flywheel from scratch - revisited
« Reply #4 on: April 05, 2014, 01:10:29 PM »
Cool idea. Thanks for posting that.
Added to my tips and ideas jar.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline smfr

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Re: Making a flywheel from scratch - revisited
« Reply #5 on: April 05, 2014, 07:10:19 PM »
That's a very nice-looking flywheel. Looks like the material cut quite nicely too!  :ThumbsUp:

Simon

Offline gerritv

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Re: Making a flywheel from scratch - revisited
« Reply #6 on: April 05, 2014, 09:38:02 PM »
Quote
Secondly, after reading through most of the active posts here, I have to admit that I appear to be the only member of this forum without a milling machine.  :'(
All my planned and actual efforts are filtered through the 'will it fit the Taig milling attachment/lathe'. Sometimes requires creative workholding but it gets done.

Gerrit
Don't confuse activity with progress

Offline Heffalump

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Re: Making a flywheel from scratch - revisited
« Reply #7 on: April 05, 2014, 10:15:14 PM »
I love this idea - I will be finding myself some cheap bar weights!

Offline Johnb

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Re: Making a flywheel from scratch - revisited
« Reply #8 on: April 05, 2014, 10:44:07 PM »
No milling machine for me either. Nice job!
John Browning. Member of Ickenham and District SME

Offline ttrikalin

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Re: Making a flywheel from scratch - revisited
« Reply #9 on: April 06, 2014, 12:26:54 AM »
ingenious  :praise2:
hats off

take care,

tom in MA

Offline fumopuc

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Re: Making a flywheel from scratch - revisited
« Reply #10 on: April 06, 2014, 05:55:51 AM »
Hi Ian, thanks for posting. Giving me some inspiration.
Kind Regards
Achim

Offline gunna

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Re: Making a flywheel from scratch - revisited
« Reply #11 on: April 06, 2014, 07:03:20 AM »
Thanks to everyone for your kind words.

Another hint I have discovered for anyone wanting to try this - some of these weights, probably the larger ones, are not cast iron but plastic coated concrete!!! Now I am no expert, but I doubt that any of you could do this with one of those.  :hellno:

Ian.

Offline burnit0017

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Re: Making a flywheel from scratch - revisited
« Reply #12 on: May 11, 2014, 12:33:19 AM »
Hi, super job. Thanks for posting. I tried to machine a 10 pounder with HSS and it just removed the paint. What did you use to machine yours????

Offline gunna

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Re: Making a flywheel from scratch - revisited
« Reply #13 on: May 11, 2014, 07:31:05 AM »
Hi Burnit, I used one of those tipped tools with the triangular inserts, carbide? I suppose. From memory, it took at least two points off the insert. Towards the end, it became a case of 'stuff it' I will keep going, knowing that the final clean up could be done with a HSS tool. That cast iron skin can be pretty tough. Sometimes a light 'lick' all over with an angle grinder will help.

Ian.

Offline Camm-1

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Re: Making a flywheel from scratch - revisited
« Reply #14 on: May 11, 2014, 01:12:37 PM »
I tryed to one day.
Have some weights laying and put one up in the chuck but all that happens was sparks flying around
The tip :shrug:

Offline NickG

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Re: Making a flywheel from scratch - revisited
« Reply #15 on: May 11, 2014, 02:52:47 PM »
Looks great that, often see the weights in tesco and wonder whether it's doable - now I know it is! Thanks.

Offline Baron

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Re: Making a flywheel from scratch - revisited
« Reply #16 on: May 11, 2014, 08:20:12 PM »
Thanks to everyone for your kind words.

Another hint I have discovered for anyone wanting to try this - some of these weights, probably the larger ones, are not cast iron but plastic coated concrete!!! Now I am no expert, but I doubt that any of you could do this with one of those.  :hellno:

Ian.

Hi Ian,

You need to carry a magnet when you go to buy one !

I used a 10" diameter weight for my tapping stand base.

Best Regards:  Baron.

I donít regret the things Iíve done, I regret the things I didnít do when I had the chance.

Offline gunna

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Re: Making a flywheel from scratch - revisited
« Reply #17 on: May 12, 2014, 09:50:52 AM »
I may be wrong in this, and someone will correct me if so, but I think the trick to machining cast iron is to make the initial cut as deep as the lathe will permit (within limits of course) and go right in under the hard skin in one pass. It sounds brutal but I think that is the way. Maybe grinding a little from an edge to give somewhere for the tool to enter first.

Ian.

ps Nice stand, Baron.

Offline steamer

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Re: Making a flywheel from scratch - revisited
« Reply #18 on: May 12, 2014, 10:55:28 AM »
Wot gunna said!....

I still like carbide for stuff like that though....but I hate cheap iron....with hard spots.... >:( it's dirty enough as it is without being a PITA to cut also!


Dave
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Damned ijjit!

Offline NickG

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Re: Making a flywheel from scratch - revisited
« Reply #19 on: May 12, 2014, 01:01:35 PM »
Dave you make a good point - it would be easier to machine this from a nice piece of free cutting mild steel that is round to start with and probably not much more expensive (if at all) to get a blank that width.

Offline Ian S C

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Re: Making a flywheel from scratch - revisited
« Reply #20 on: May 12, 2014, 02:15:22 PM »
Some of the weights that I'v seen appear to be slices off a bar of hot rolled mild steel.
                                              Ian S C

Offline Baron

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Re: Making a flywheel from scratch - revisited
« Reply #21 on: May 14, 2014, 05:39:40 PM »
I may be wrong in this, and someone will correct me if so, but I think the trick to machining cast iron is to make the initial cut as deep as the lathe will permit (within limits of course) and go right in under the hard skin in one pass. It sounds brutal but I think that is the way. Maybe grinding a little from an edge to give somewhere for the tool to enter first.

Ian.

ps Nice stand, Baron.

Thanks Gunna,
You beat me to it !  I was going to say exactly what you said.

Quite a few years ago I was mentored by a very experienced turner.  He let me into the secret of turning castings.  Actually he was very scathing when I said that I was going to buy a Myford lathe.  He said something to the effect that I should get a lathe that you could put a real cut on.  At that time he was using a Ward 7A to turn V belt pulleys from castings.  He often made the point by taking an initial 1/4" cut on a 12 or 14" pulley.  At 60 rpm or so material would come flying off like a red hot shower.  I've seen him drill 2.5" diameter holes in one go for taper lock bushes.

Best Regards:  Baron.

I donít regret the things Iíve done, I regret the things I didnít do when I had the chance.

Offline gunna

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Re: Making a flywheel from scratch - revisited
« Reply #22 on: May 15, 2014, 10:04:06 AM »
Yes, I had a similar teacher at tech school, He was ex GM car manufacturing and seemed to think that any lathe under about 24 inch swing was just a toy. A bit hard to make some of our little parts in a 20 inch 4-jaw though.

Ian.