Beginner trying to ‘thin out’ a flywheel

This topic has 16 replies, 8 voices, and was last updated 23 June 2015 at 17:24 by Gas_mantle..

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21 June 2015 at 16:33 #194328
Gas_mantle.
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@gas_mantle
Hi all,

I am trying to make a small flywheel (more as a learning exercise than anything), it's just over 50mm dia and 13 mm thick at the moment and is made of mild steel.

I'd now like to thin out the 'spoked' area leaving a thicker hub and circumference, can anyone please offer a few tips of how best to go about it ?

I don't have access to a milling machine

My 8×16 lathe seems to cope ok dealing with intermittent cuts past the 'spokes' but I only take very small cuts

(I realise the holes are a little bit uneven but it's about my skill level at the mo !)

Thanks

Peter

Edited By Peter Nichols on 21/06/2015 16:34:39
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21 June 2015 at 16:33 #7675
Gas_mantle.
Participant
@gas_mantle
21 June 2015 at 17:22 #194336
Thor 🇳🇴
Participant
@thor
Hi Peter,

You may need a socalled trepanning tool, here are a few links that you may find useful:

***Link***

***Link***

Thor
22 June 2015 at 08:26 #194407
john carruthers
Participant
@johncarruthers46255
Snap! almost exactly what I shall be doing later.
I shall reverse the jaws in the 4 jaw chuck, pop the wheel in and centre it up, then take a few slow cuts.
22 June 2015 at 09:20 #194411
Eric Cox
Participant
@ericcox50497
What I did was to use a boring bar. Have a minimum of over hang and cut from the holes towards the rim. Wind the cross slide to put the boring bar past the centre of the fly wheel. Put your lathe in reverse and cut from the holes to the hub.
22 June 2015 at 09:43 #194416
Gas_mantle.
Participant
@gas_mantle
Thanks guys,

I'd never even heard of a trepanning tool, I'll read up a bit more about them

It looks like I'm attempting a similar engine John. The way you mentioned is how I got to this stage.

To get the side faces done I just used an ordinary tool taking very small facing cuts but thought that could be difficult when I try to recess the cuts. The banging the tool makes is a bit disconcerting for a novice but it doesn't seem to bother the machine if I take very light cuts.

I did wonder about a boring bar, I bought one a few days ago and it's not even been out the box yet. I'll try it on a few simple boring tasks to get the hang of using it before trying anything a bit more adventurous.

Peter.
22 June 2015 at 09:56 #194418
john carruthers
Participant
@johncarruthers46255
Slow it down for any interupted cut, minimum tool overhang (without fouling the chuck).
To get a feel for it try facing off a bit of rectangular scrap, you'll soon find a comfortable speed/feed. You soon get used to the "chonk – chonk- chonk " noises.
22 June 2015 at 10:04 #194421
jason udall
Participant
@jasonudall57142
I don’t know about a boring bar , specifically, but, with in effect a facing operation over interruptions ..the risk is from the tool “falling” down the hole..any sping.backlash.slop.etc that allows the tool to move to take a big bite during the interruption will be fun

So .sharp sharp sharp.
Light cuts.
Lock slide
Low over hang ( think about a “special “tool with say only mm of projection)

Now to the question of finish.
The interrupt will show in the finish adjacent to the hole. .and all of the above will help reduce this.
…
22 June 2015 at 12:05 #194442
Neil Wyatt
Moderator
@neilwyatt
I used a v-pointed tool with quite steep angles to do this on rail;way wheels. You can mount it aligned along the length of the lathe plunge it into the work and put on cuts either towards or away from the centre. This leaves an angled bevel to the hub and rim of the wheel and works best with a fairly shallow recess.

Neil
22 June 2015 at 12:19 #194446
Gas_mantle.
Participant
@gas_mantle
Thanks for all the replies,

I guess really I should have cut the recesses before drilling the holes but at the time it seem to make sense to drill the holes first, I need to plan ahead !

I wanted to reduce the thickness by cutting the recess about 2.5mm deep each side (it's currently 13mm thick) just to give it a more decorative effect, so the dimensions aren't critical.

I think I might be a bit optimistic at my skill level to reduce it that much so may just have to make do with a light decorative cut.

Peter.
22 June 2015 at 13:27 #194455
Ian S C
Participant
@iansc
This is a little flywheel on a wee hot air engine, its around 50 mm dia, and made of stainless steel, after thing the spoke area, the holes between the spokes were chain drilled and the spokwe formed by hand with a file. the bulk of the metal in the spoke reagion was removed with a normal lathe tool(HSS), then the inside of the rim was squared up with a boring bar(HSS), the hub was turned with the same boring bar, with the lathe in reverse, and the tool on the far side of the hub(a bit risky, the lathe has a screw on chuck, light cuts on a small dia, not to muc torque). Ian S C
22 June 2015 at 14:52 #194472
Gas_mantle.
Participant
@gas_mantle
Hi,

I'm glad you mentioned making a spoked wheel with a file, I have limited tooling as I'm just starting out in this hobby and did consider trying to make spokes by hand. In the end I decided the drilled holes were a compromise between ease of build and looks. As it is I've made a mess of it now :-

I found using a 'V' pointed tool point straight at the work was working great, it was cutting a nice chamfer on the rim and hub (I like how the hub turned out) but when the chamfer on the rim was getting too deep I angled the tool to cut the remaining recess parallel and found I couldn't cut the rim side and hub side without realigning the tool. From there on it went downhill rapidly

I'll have rest from it today and try again tomorrow, as it is the diameter of the recess needs increasing anyway at the moment the rim chamfers are too close to the spoke holes.

Peter.
22 June 2015 at 15:29 #194478
Gordon W
Participant
@gordonw
Don't worry, that will clean up ok. I use a V tool but with a decent radius on the tip for that sort of thing.
23 June 2015 at 11:46 #194585
Eric Cox
Participant
@ericcox50497
To reduce the "banging" as you are cutting the recess, drill the holes 2mm and then open them up full size after you have finished machining the flywheel
23 June 2015 at 14:22 #194605
Ian S C
Participant
@iansc
When you enlarge the (above)2 mm holes, clamp the flywheel down so that it is ridgid as the larger drill will try and chatter, also you might be tempted to hand hold it, it's best not to, if it catches it will be a bit hard on fingers, and being off centre it will do it's best to break the drill.

Ian S C
23 June 2015 at 15:29 #194611
Neil Wyatt
Moderator
@neilwyatt
Easily salvaged, angle the tool so it 'points' into the corner between rim and 'spokes' then turn the inside of the rim flat. Leave a little metal so you can clean up the spoke face at the end, blending into the existing surface.

If the tool is banging (alarmingly) when you cut past the holes you are feeding it too deep, but I don't get the impression this has caused you any problems?

Neil
23 June 2015 at 17:24 #194621
Gas_mantle.
Participant
@gas_mantle
Hi all,

The banging of the tool isn't a problem, I'm now beginning to get the feel of the machine and can to some extent sense when it's struggling. I only take very small cuts also.

I had a go at the reverse side today and made a right mess of it, It's only really a learning exercise so to be honest I'd be happy if I can get it to look ok rather than for it to be super accurate.

I'll post a couple of photos shortly and you can see how I've butchered the reverse, it looks like I turned it using a plough !

I probably should have put this in the work in progress section then you can see how I hack the rest of it to bits over the coming weeks !
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