# Flywheels from plate revisited.



## Bogstandard (Apr 15, 2008)

I did a post about how to make flywheels out of plate last year, and just before christmas I lost all my pics on bucket, with no backup. So the post is now effectively dead.
So what I have done, because I have got to make some flywheels for the finger engines I am building, I have made a basic post to show you how to end up with a disc, ready for making a flywheel out of. It might be old hat for more experienced members, but it just might help a newbie out of a jam.

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I need three thick ali flywheels, 2.75" diameter. Not having any round stock in at that size or larger, I make them out of plate material, It takes a little longer but it is a lot cheaper if you can get the plate like I do, old jigs being thrown out of factories.

This is a piece a friend rescued for me, about 18" long, 3" wide and 1" thick. A major problem with using this type of rescued material, is that after you have stripped all the bits off it, it will be covered in holes, all usually in the wrong place for what you want to do with it. On this piece there were holes along each edge, but at different spacing each side. So I had to find a position where I could get my flywheels out of it. As you can see, I have marked out the positions, with a pop mark in the centre of the scribed circle.








The hard bit now is getting that disc out of the material, you don't have to cut out a circle as I have done, it can be a square if you are hacking it out with a hacksaw. I use my little vertical bandsaw, and half an hour later I have my rough blanks. If you look at the upper left one, that was the first one cut, upper right, second one and the third is the one at the bottom. Notice as they get much neater the more you cut. This is because the material is getting smaller after each one, and so is easier to handle. The pop mark in each one was centre drilled to a depth to give a diameter on the outside no larger than the spindle you are going to be using.







On the back side of the plate, other side to your centre drilling, position some strips of masking tape, super accurately, just as I have done. This is going to be your friction drive.







Put a bit of bar stock into the chuck jaws as shown, in a bit from the front and tighten up. The size of the barstock should be so that when the jaws are tightened, the outside diameter of the jaws are slightly smaller than the finished diameter of the disc.







The next bit looks a bit awkwards, but it is easy to do. Set your tailstock as near to the chuck as possible, without stopping the saddle movement giving you a full cut across the outer face of the material. A rotating (live) centre has to be used, a solid centre will not work. Wind out the tailstock with the job positioned with the centre hole on the rotating centre, and gently wind forwards until the job is trapped between the centre and the chuck jaws, do not tighten it up too much at this stage. Turn the lathe chuck to see if there is any wobbling on the tailstock ram, if it does show, back the centre off and come in again, repeat until no wobble shows, then tighten the centre into the job and lock the tailstock ram.
I run the machine at the same speed as if the job was in the chuck, it is a totally safe method of turning.







Because you are working in areas that you don't normally go with a lathe tool, ie further than the front of the chuck jaws, make sure that you have your tooling set so that nothing will hit the chuck while cutting metal. You will have fairly large interupted cuts to begin with, just take it steady and it will soon get down to size. If you try taking too heavy a cut, the job will just stop and the chuck will continue spinning, just take off the heavy cut and carry out a slightly shallower one. I can take 0.025" cuts each way, I have a profile tool that allows it to be done, so mine gets down to size twice as fast.







Here are the three bits that I require. The whole job took less than an hour. The machining part only takes minutes, it is the rough cutting that takes the time. It doesn't have to be ali as I have used, this will work with almost anything (rubber goes a bit wobbly).






Thats it.

If you want to see any further progress on these discs, you will have to chirp up pretty quick, so I can take piccies of the next stage.

John


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## J. Tranter (Apr 15, 2008)

Please keep going.


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## hitandmissman (Apr 15, 2008)

By all means keep going. I along with a lot of others would like to see more on this. Thanks Bogs for the great postings.


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## snowman (Apr 16, 2008)

You are NUTS! 

My tailstock doesn't hold well enough to do that, but it's a great idea. 

Never thought of using masking tape as dogs.


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## Bogstandard (Apr 16, 2008)

Snowman,

It is not an idea, it is fact. Been using this method for more years than I care to remember, and on bits a lot larger than this.

Shame your tailstock isn't up to it.

John


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## kellswaterri (Apr 16, 2008)

Hi john, I have not tried this method of friction turning flywheels with DBL sided tape yet...looks like a useful tool to me, only thing I note as you say ...if too heavy a cut is taken, job stops and chuck spins...surely that would damage and destroy the friction bond of the tape thus needing a renewal of the tape??
                                         John.


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## John S (Apr 16, 2008)

So don't take such a big cut :big:

As an aside The old MES Services kit for the Dore Westbury miller that had built up flat slides, advocated a layer of PVA wood glue, a strip of news paper, more glue and the next piece of the slide, clamped and left to dry.

Then all the machining, thru drilling etc was carried out and put in a bowl of hot water to part.

If you substituted newspaper of drawing paper it was immensely strong.

John S., the third.


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## cfellows (Apr 16, 2008)

I've used this method of turning disks & wheels for years. It works very well as long as you don't try to take heavy cuts. You can also remove the work piece for inspection and return it to the lathe without re-centering. It's a very convenient way to turn disks.

Chuck


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## Cedge (Apr 16, 2008)

John
I tried this technique the first time you posted it. Admittedly, I was dubious of the safety aspect, but after doing it a couple of times, it is a quick and easy way to get the job done. Keep the tips coming. I'm steadily absorbing them into my own arsenal.

Steve


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## Alphawolf45 (Apr 16, 2008)

Good trick..I never seen that masking tape trick done before and I wouldnt have thought of it on my own.... I like it, thanks Bogstandard


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## Bogstandard (Apr 16, 2008)

John K,
It isn't double sided tape, but masking tape. So you will find it will carry on driving even though crunched up. If it doesn't, just a tiny bit more tailstock pressure will restore full grip again.

I must tell you that this method doesn't always give a perfect thickness all over, usually within a thou or so. I always true up afterwards.

Mass demand has called on me to carry on with the post (one would have been enough), so hopefully this evening I will drag myself out to the shop and show how to true them up, not by using the equipment that I have at my disposal, but with what almost everyone on here should have.

Bogs (this is to keep the names problem under sane control, too many of us Johns about)


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## kellswaterri (Apr 16, 2008)

Hi Bogs, another ''Senior'' moment... the penny has finally dropped.
                                            John.


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## Bogstandard (Apr 16, 2008)

This might seem to be a long post by the time it is finished, you will only get a little bit every time. The reason being is that I am having to make three, even though I will be showing just one, I have to do all three one after another, so it does take a bit more time.
I will just explain what I will be doing. Normally I would have just put the bits into a custom bored soft jaw, and that would have been it. Because not all people have soft jaws, I will be showing how to do it using what everyone has available, outside jaws. They won't be as accurate as I normally do it, but will be acceptable to 99.9% of the members. If the other 0.1% want them more accurate, I'm sorry, you are on your own with this one.

Before I start cutting metal, I want to see what will be needed, it is called forwards planning. A thing I do all the time, just so no unexpected surprises occur.
From my previous post about building finger engines, I came to the conclusion I wanted the same retro three spoke, heavyweight looking design, With 1/4" square spokes. This design of flywheel definitely worked a lot better than the skinny one.

http://www.homemodelenginemachinist.com/index.php?topic=862.0

So I did a quick layout, just to see what was needed, and to get a few basic measurements.







This looks like a design for a new mousetrap, but I will explain on the next pic. The previously drilled centre was put towards the chuck, I did not want to use that because it just might be slightly off centre. Of course, you have noticed that I am using my outside jaws on my three jaw self centreing chuck.







Here is another view of the setup, and why I had to do it this way. I needed to be able to machine about 2/3rds of the outside face, you will see this later. The parallels are resting between the jaw faces and the back face of the job. The jaws were tweaked up and the job tapped back until all three paras were gripped. A bit more pressure on the jaws and the paras were taken out.







Faced off, a new centre drilled and the job was drilled and reamed. If you fancy a bit of fine boring to get your middle hole, do that at this stage. I will be mounting the flywheels in a rather unconventional way, so reaming suits what I am going to do.







The outside face was skimmed down to finished size (only about 5 thou) as far as I dared go before hitting the chuck with the cutting tool.
What I am doing most probably looks stupid, but now when I explain, you will realise my madness. By doing it this way, all from one side, I have the front face, the bored hole and two thirds of the outside face all perfectly square to each other. Forwards planning pays off again.







The job was flipped around in the chuck, but no parallels this time, just tapped back until firmly against the chuck jaws. The front face was then machined to bring the blank to correct width of 3/4".







The outside face was then machined down to blend with the previous outside edge machining. It is at this time you will find out just how far you chuck is out of wack. Mine blended in to within about 1 thou, which can easily be blended in with a bit of emery later.
The variation of thickness between the flywheel faces was 0.0005", which as far as I am concerned is close enough.







Two more done and this is the result.
They don't look much different to the previous post, but they are now accurate in their dimensions.







Next will be getting the recesses in to a depth of 1/4" each side.

John


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## BobWarfield (Apr 16, 2008)

John, I like your method for holding the blanks. Once the live center is snugged up, whatever you're doing would have to take out that tip (bent or broken) before things get too crazy. Should be fine for model flywheels, if perhaps not ideal for a big heavy piece.

I am also intrigued by your little round insert turning tool. Seems really nifty to be able to approach from so many points on the compass. Who makes it and where did you get it?

Best,

BW


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## Bogstandard (Apr 16, 2008)

Bob,

I have turned the faces of lapping plates up to 2ft diameter, 2.5" thick cast iron and weighing a lot, using the friction method, but at that size, you don't need the masking tape. Not on the machine I have, but on a large Triumph. So I think these weeny little things have a good chance of not causing any problems.

About the turning tool, I have just been asked that question, here is the post

http://www.homemodelenginemachinist.com/index.php?topic=1813.0

John


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## Bogstandard (Apr 17, 2008)

Here we go again, more boring pictures of circular lumps of ali, at least you are the ones that asked for them this time.


What I have done here is to take one of the trued up blanks and marked on it the rough positions of the finished sizes, allowing about 25 thou under and over size for final clean up.
This will be the one that I will use to get my lathe dial settings for cutting all the other recesses.







The part was mounted into the chuck in a position where I could scribe a line with a tool of known spot on centre height, I can lock my chuck in position, but if you are careful you can get away with it on a non lockable chuck.







If you go to this post, it shows how I ground up the tool for cutting flywheel recesses, there is also a vid showing how I cut one. 
http://www.homemodelenginemachinist.com/index.php?topic=844.0
This pic shows how I set the tool to height using the scribed mark, and also making sure that the full face is in contact with the job.







If you have a saddle stop it makes plunge cutting a piece of cake, if you need to make something for your lathe, a saddle stop should be high on your list of priorities. If you haven't got one, then you need to touch the tool on the face, lock the saddle and plunge in using the compound to about 5 thou short of final depth, wind out, move across about half tool width and plunge in again.
The first plunge in is where you are liable to break the tool, there is little area for the swarf to be cleared away, so you might have to peck down to depth to keep the cutting tool clean. This process is almost exactly the same as parting off, if you hate doing that, you will be the same with this. No one will be able to show you the right or wrong way, they will show you 'maybe' cures that work for them, but it all boils down to experience and be willing to hack thru it and find something that works for you.







Once the initial groove is cut, the tool is retracted and then moved across about half the cutter width and plunged in again, This time it will be a lot easier, but the tool does tend to chatter, mainly at the bottom of the cut.







The recess was cut until I touched on the inner mark. Notice all the chatter marks at the bottom, no worries, they will be cleaned off later. It looks like I have not come out far enough with the recess, but that is just a swarf scratch mark on the bluing. The other five recesses were done in the same way and to the same settings, which I wrote down, so I knew where to cut to without any markings.







Three lumps of round ali, with rough as old boots recesses. But again, no worries.
If you see the vid in the 'recess' post it shows how the recesses are cleaned up.







Brought to wanted size, and cleaned up with a bit of emery. Now they are starting to look something like flywheels.






The bit that I really enjoy comes next, working out where to stick the cutter in. Then putting them on the RT and see if my calculations are right or not.

John


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## BobWarfield (Apr 17, 2008)

Doggone!

Just makes we want to go out into the shop and make a flywheel. Looks like fun!

That darned button tool winks at me every time I see it. And how did I miss your trepanning article? Just had to make such a tool, couldn't find a decent pick, and what I botched together chattered way too much. I'll try yours next time. Thanks for these series, they're good fun!

As to a saddle stop, maybe there I have an idea:






The Kant-Twist is a miraculous invention for machinists. I can't get enough of them large or small. I got a set of 8 of these little ones and use them constantly. They wind up clamped all over the shop waiting until I need them. Their little jaws are soft and don't mar things. I like them better than machinist's clamps for most things and haven't touched a C-clamp since I got them.

Cheers,

BW


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## Bogstandard (Apr 18, 2008)

Good tip on the saddle stop Bob. 

The final part.


What I have done here is done a rough mark up on one of the blanks and done a little procedure writeup for me to follow while I cut the bits out on the flywheel.
Half way thru, I noticed a bit of broken test tube on my benchtop. So duly went to pick it up, and the damned thing bit me, causing a big gash on my finger, so the finger was wrapped up in an oily rag (standard procedure, unless the digit has actually come away from the hand), and then I carried on, blood everywhere. A spot on each part ensures the engines will work perfectly.







Part was popped into the RT, and because it had a centre hole, a bit of rod was used to get it very close to central. The RT was set to zero.








Out came the trusty DTI and the part was centred spot on.
It was at this time I did a check of my machining procedure, and noticed I had made a small mistake on one of the measurements, plus one arm was now empty of blood, so I went to seek medical assistance from her indoors.
While she was stitching my arm back on, I had a brainwave (a very rare occurrence nowadays). Why not use Marvs 'Flywheel' prog, instead of recalculating mine. I had used Marvs program before, but not with so few spokes and the hub and outer rim so close together. But if it didn't look any good, I could always use my figures to modify it. So nothing lost.







After I inputted the figures, this is what it came up with.
It was then I noticed the better half had put the arm on the wrong side, isn't it great, having two right arms means I can get twice as much done.







Armed (pun not intended) with the figures from the printout, I followed the procedure and drilled the holes where it told me to. So far so good.







Joined up the outer holes, did all the offsets and machined between the inner and outer holes. Still looking rather promising.
When all the holes were joined up it didn't look at all too bad. Normally you have to do a fair amount of hand blending to get it looking something like. This was no exception. But a little less than normal.
A bit of bling, a quick runover with some emery and the flywheel was almost finished.







Nice one Marv, this will do me just fine. Now if you can rewrite the program for giving straight spokes................Not really needed, they are easy to do anyway.
The other two will be given the same going over. Then they will be sent away to get the spokes shot blasted before giving the rest a bit of a polish.






A bit different to the crappy lump of plate it all started off with.


Hope you have enjoyed this little series.

Have really, really, got to get back to work now rather than playing about. Got lots of engines to make.

Awe, blow it, I'll start tomorrow. It will give time for all the injuries to heal.

John


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## alan2525 (Apr 18, 2008)

Thanks for taking the time to post this little tutorial!

All the step by step photographs are really appreciated! Although some with the blood soaked paper were a little graphic! Hope the injury heals up ok!

Using a lathe with rags wrapped around injured fingers, is this ok with current health and safety practice?

One of the kids where I work, powered up a lathe and in the fraction of a second it took for my words "SWITCH THAT OFF!!!!!" to travel across the room to them - immediately put their hand straight onto the chuck which was running about 500 rpm!

I've never felt like trying to grab a 6" self centering 3 jaw on a big old colchester lathe! Luckily the previous job was only small diameter and the jaws weren't projecting from the chuck body...otherwise could have been a real knuckle cruncher. It's never nice to ask kids how many fingers they had at the start of the lesson....


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## BobWarfield (Apr 18, 2008)

Nice stuff!

RE the notebooks everywhere--one of the most useful purchases I ever made for my shop was 3 things at the office supply:

- A package of 10 steno pads. There's always one available to jot stuff down on. 

- A full box of Sharpie markers. Again, there's always one nearby, and more in the bin I keep them in if I need a fresh one.

- An HP calculator with trig functions.

Nice flywheels again. Good sense of the aesthetic!

Thanks,

BW


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## Bogstandard (Apr 18, 2008)

Alan,

After a while you will realise there is usually a little bit of weird humour sometimes in my posts, so don't take them too seriously. Just take them for what they are, a bit of light relief.

John


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## alan2525 (Apr 18, 2008)

Bogstandard  said:
			
		

> Alan,
> 
> After a while you will realise there is usually a little bit of weird humour sometimes in my posts, so don't take them too seriously. Just take them for what they are, a bit of light relief.
> 
> John



The humour is appreciated!


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## applescotty (Apr 18, 2008)

John,

Great writeup. I really appreciate all the time you put into these posts.

I can't quite tell from the photo, but the 'spots' around the edge look somewhat like a recessed rivet. Nice look. What did you use to make these marks?

Scott


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## mklotz (Apr 18, 2008)

John,

The FLYWHEEL program will do straight spokes very nicely, thank you very much. I've used it numerous times in that mode. Simply specify d1 = d2 or theta1 = theta2.

The only rewriting it needs is an option for locating the recesses in the spokes for the rhinestones.


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## Bogstandard (Apr 19, 2008)

Scott,

This is a 5/16", No 8, 60 deg end mill. Because the recess is very shallow in the centre, it will only penetrate about 50 thou, but I only go about 30 thou deep.








Marv,

In words of two syllables or less, can you tell me what input I should be putting to get straight sides, this is the input to obtain what my wheels were done at. I must be doing something wrong somewhere.







John


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## Bogstandard (Apr 19, 2008)

Marv,

Just had a play about with your prog, and got it to make straight sides, but they end up too wide (over 1") for my needs.
I will have to go back to my own method of drilling four holes for the cutouts. Its easy enough for me to do.

But your program does make real classy tapered spokes, and I have used it before and got great results.

John


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## mklotz (Apr 19, 2008)

John,

Referring to the diagram that's included with the FLYWHEEL.ZIP archive.

d2 = offset of inner hole from central axis of spoke

d2 = r2 * sin(theta2)

r2 = radius of inner holes [0.5 in your case]
theta2 = 180/N where N = number of spokes [180/3 = 60 in your case]

Therefore:

d2 = 0.5 * sin(60) = 0.433"

When the program asks for d1 (prompt says "offset from spoke CL to outer hole center"), simply enter 0.433.

Now, when you examine the output, you'll see that the inner and outer spoke widths are both equal at 0.616", i.e., non-tapered spokes.


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## Bogstandard (Apr 19, 2008)

Thanks Marv,

I have been waiting for your answer.
I went a slightly different route, but it does show because of the single inner hole, the spokes do get rather wide unless you make the inner hole larger.

At least I have the choice, my way and yours, and the one that I have just done has a very 'Mercedes' look. So I will be doing that with the others.

Many thanks

John


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## mklotz (Apr 19, 2008)

If you think about it, you'll see that the spoke width has to be related to the diameter of the inner holes. Those holes "span"* the space between two adjacent spokes so, for the spokes to become smaller, the holes must grow larger.

In my earlier post, I mistakenly typed cosine for sine in two places. I've gone back and corrected that now. Sorry for any temporary confusion I may have caused.

---
* "Span" is used here in a decidedly non-mathematical sense. For the proper mathematical relationships, refer to the diagram.


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## cfellows (Apr 19, 2008)

mklotz  said:
			
		

> If you think about it, you'll see that the spoke width has to be related to the diameter of the inner holes. Those holes "span"* the space between two adjacent spokes so, for the spokes to become smaller, the holes must grow larger.



Or, you can drill the same size inner holes on a smaller radius...


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## Bogstandard (Apr 20, 2008)

Too late now, they are done and dusted.

Worked out at about 4 hours total from recessed blanks to having these done.
So it does pay to have the paperwork ready.






John


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## Brian Rupnow (Dec 17, 2008)

I just tried Bogstandards "masking tape method"--I have to say, it works most excellently. Thank you, Bogstandard.---Brian


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## T70MkIII (Dec 18, 2008)

I really like the 60* endmill treatment - it provides a nice touch of Victorian Steam-Punk. Very nice work, and thanks for the lessons.


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## tmuir (Dec 18, 2008)

I recently tried it too and I'm pleased with the results even though I haven't finished yet as I have to make a tapping tool before I make the boss.















AFter this photo was taken the lathe jaws were opened up to make it more steady .











Not finished yet but pleased with it so far for my first try at something like this.


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