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How to machine a flywheel ?

Correct positioning on the face plate.

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Brian John03/10/2015 07:23:57
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I have been machining flywheels using my newly made steel mandrels. Everything was okay on the smaller flywheels (50/60mm) but then I had a go at some of the larger flywheels and struck a problem. The 75mm diameter flywheel cannot be held in my lathe chuck ; my lathe is too small. I have tried both internal and external jaws and I cannot get a good safe grip. I only need to face off the hub and drill a hole for the mandrel/axle. I can then fit the mandrel and do the outer rims and the outer surface.

There is a 10mm diameter hub with 5mm sticking out. is it safe to grab the flywheel as per the photos ? I cannot see any other way to do it. The flywheels are aluminium and brass so they are easily machined.

Some of my other flywheels do not even have a hub sticking out so I think a face plate is the only option with those.

flywheel 1.jpg

flywheel 2.jpg

Edited By Brian John on 03/10/2015 07:26:06

JasonB03/10/2015 07:42:41
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Have you tried the jaws that you have fitted at the moment but opening them outwards so the step on them grips the inside of teh flywheel?

Brian John03/10/2015 08:21:46
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Yes, I tried that but by the time the step has reached the rim of the flywheel then the jaws are out of the chuck thread.

JasonB03/10/2015 08:25:57
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Looks a lot closer in the photo, use the step nearest the chuck body

David Clark 103/10/2015 08:25:57
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Faceplate would be best and machine bore and outside diameter at the same time.

Brian John03/10/2015 08:33:28
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Jason, no it will not work like that. I have fiddled with it many times. it cannot be gripped on that first step (nearest the chuck body) as the second steps (closer to the centre) will not pass through the spokes. With a different spoke configuration it may have been possible.

David : yes, I think a faceplate is the only answer but there is no face plate for this model so one will have to be made. I am having problems getting the chuck off to see what fittings are required as the nuts are on VERY tight ! I will have another look tomorrow.

Bob Brown 103/10/2015 08:47:56
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Why not get a piece of material and machine it such that held in the chuck it acts like a face plate you can then drill and tap some holes in it to clamp the flywheel to it bit like a jig. To ensure the face is square just take a skim off it before clamping the flywheel on.

Bob

Engine Builder03/10/2015 08:48:31
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Here is a video of a flywheel being machined.

Michael Gilligan03/10/2015 08:51:17
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Brian,

My advice: Buy a small faceplate [any suitable size] and make a spigot to fit it.

Clamp the spigot firmly in your chuck and away you go.

... it probably won't run perfectly true, but you will be levelling the Flywheel blank anyway and I think it's the safest option.

MichaelG.

 

Edit: Bob beat me to it.

Edited By Michael Gilligan on 03/10/2015 08:52:22

Hopper03/10/2015 09:10:08
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In the absence of a faceplate, you might be able to undo the three or four nuts that hold the chuck to the flange on the spindle. Then use the flange as a faceplate by holding the flywheel to it with some nuts, bolts and washers. Or get a disc of ally from Norweld and bolt it to the flange then face it off and drill bolt holes wherever you need them. Tonkins also often have steel discs on the offcut bench -- "holes" from larger jobs on the CNC laser cutter.

Your lathe will take a much larger chuck than the one it came with. I would recommend a four-jaw independent chuck. You are going to need one sooner or later for holding castings and other non-round items for machining. A 125mm four jaw is a very handy thing to have, if it will fit your lathe. If not, a 100mm is pretty handy too.

For the flywheel in your picture, you might get away with holding by the hub like that. Take light cuts and drill gently. You may have to rap on the rim of the flywheel with a soft hammer (aka handle of a screwdriver) to get it running reasonably true before starting to machine the hub.

Or at a pinch, you might be able to make a simple face plate out of a piece of 20mm thick wood with a hole bored thruogh the centre, say 50mm diameter, that you can grip with the chuck jaws from the inside.  Does the tai tai have a cutting board and do you have the skill to explain how a 50mm hole appeared in it?

Edited By Hopper on 03/10/2015 09:15:03

Michael Gilligan03/10/2015 09:33:10
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Brian,

An alternative would be to make a 'Bell Chuck' ... have a look at the Wade items on this page, and then think bout what you could make by adapting locally available items.

You have already seen the possibilities of various pipe-fittings, so I'm sure you can find something useful.

MichaelG.

Ady103/10/2015 10:22:56
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Would a long fixed centre help? I made mine out of a bar of silver steel.

Can make awkward jobs safer and more secure and still let the toolpost in to work

long-fixed-centre.jpg

 

 

Edited By Ady1 on 03/10/2015 10:29:56

Brian John03/10/2015 12:28:50
1455 forum posts
579 photos

The slightly larger flywheels that I have CAN be gripped by the inner rim. I think that this is just an awkward example which will require the use of a face plate or by carefully gripping the hub. I think I can see how a ''face plate'' can be made to fit this chuck ie. the ''face plate'' held in the jaws and the flywheel then attached to it.

I have to go to work now but I will think about this tonight and look at the problem again tomorrow.

A four jaw chuck and a fixed steady for this lathe has been ordered from China but the Australian company does not know how much it will cost or how long it will take to get here.

I will leave the cutting boards alone for the moment as there are other options to explore. I just thought I might be missing a simple solution with the internal or external jaws. I was surprised to find that I could not grip this flywheel with either.

 

Edited By Brian John on 03/10/2015 12:31:16

David Clark 103/10/2015 13:03:46
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Hi addy1 it might be hard to bore the hole with a long centre in the way!

Brian John04/10/2015 15:07:43
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Woops, I realised that I have posted in my other thread about the lathe ! I meant to post here.

The aluminium flywheel was completed today by holding the hub in the chuck to take a facing cut on the hub and drill out to 6mm. Once this was done I fitted a steel mandrel and machined the outer rims and the main outer surface. It has worked out okay because there was enough hub to grip with the chuck. A smaller/shorter hub and a face plate would have been necessary.

The video above was interesting but he did not use an etch primer before painting the flywheel. I would not expect the paint to stay on very long without an etch primer ? I always use two coats of etch primer before painting.

 

 

Edited By Brian John on 04/10/2015 15:08:01

Brian John05/10/2015 06:33:09
1455 forum posts
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I have been digging into my box of flywheels to see what I could do with them now that I have steel mandrels to work with. The smaller wheels can be gripped from the outside of the rim, the larger wheels can be gripped from the inside of the rim and some of the wheels can be gripped by the hub if nothing else will work. I am getting a very good finish using the mandrels.The photo bellows shows four wheels that have been machined (top row), two wheels which can be machined (middle row) and one wheel (bottom row) which will need a face plate as there is no hub to grip.

But I have one aluminium flywheel (last photo) mounted in my lathe now which is giving me some unexpected problems. There was a large hub to grip so after getting it to run true in the chuck, I faced off the hub and drilled out to 6mm. But when the mandrel was fitted to begin machining the outer edges I am getting a ''fish scales'' pattern accompanied by a bell-like ringing sound. I have not come across this sound before. I have adjusted the speed higher and lower and I have changed tools. I have also tried different angles for the tool but nothing seems to work. Any suggestions ?

UPDATE : the wheel makes that ringing sound even when I strike it lightly with a wooden paint brush. Perhaps this wheel is the perfect size for vibrating which is making it awkward to machine using a mandrel ?

flywheel 3.jpg

flywheel 4.jpg

flywheel 5.jpg

 

Edited By Brian John on 05/10/2015 06:35:47

Edited By Brian John on 05/10/2015 06:38:09

Edited By Brian John on 05/10/2015 06:47:05

Edited By Brian John on 05/10/2015 06:47:52

JasonB05/10/2015 07:39:23
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The tool is chattering at a high frequency which is the ringing you can hear and the cause of the patterned surface. Basically the flywheel being larger than the others is not supported enough and is flexing away from the cutting tool.

Try slowest speed, very fine cut, very sharp tool.Use the tailstocj ctr to support the mandrel

Edited By JasonB on 05/10/2015 07:56:53

Brian John05/10/2015 08:03:26
1455 forum posts
579 photos

I have tried everything except the tailstock centre (I should have thought of that...thank you ) . I have to take my wife somewhere now but I will give it a go tomorrow.  I really think that this one will need the face plate.

Edited By Brian John on 05/10/2015 08:04:20

MichaelR05/10/2015 09:05:10
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You could make a Plywood/Chipboard faceplate to fit your mandrel and back your flywheel onto the wood faceplate by lightly clamping the flywheel by the spokes, this should stop the chatter as mentioned by Jason.

I used this method when I did the flywheels for my Wyvern and Centaur gas engines.

Mike.

Michael Gilligan05/10/2015 10:06:45
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Brian,

I think Jason's advice will see you through the immediate problem; but I would just like to say that "fish scales" was probably the best graphic description I have seen for chatter marks.

MichaelG.

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