What’s this officially called?

[Graham RounceParticipant @grahamrounce14492]

Michael – Of course I would! I’m not superstitious!

[TerrydParticipant @terryd72465]

Hi Graham,

You are truly optimistic if you think that 6" diameter tube of those dimensions will be anywhere approximating round, good luck,

Regards

T

[Graham RounceParticipant @grahamrounce14492]

Hi – I was thinking that the tubes would be made to fit together with standard fittings, elbows etc, so would have to be pretty round. Well, one can only try – they may not sell it in 6mm lengths anyway !

[Ian S CParticipant @iansc]

The 7" ring will be approximately round, but you should be able to average it so it balances. I built a flywheel of a similar size, and you could too. Around the rim I drilled six holes to match the diameter of the spokes (I used old bike spokes). For a hub use a hex nut, with a bore that can be drilled to suit the shaft, drill six holes around the nut, but not into the center hole. Fix the nut to a board, and mark a circle for the rim. Using loctite, glue the spokes to the hub by poking them through the rim, let it cure, center it and put loctite on the spokes at the rim, and after it cures, trim the spokes to length. Ian S C

[Graham RounceParticipant @grahamrounce14492]

Ian – thanks for all that. I think I’ll be using the hopefully precision-drilled-to-3.18mm Meccano bush wheel for the hub – I haven’t heard back from him/them yet.

Any tips for balancing it? I was thinking of “hanging” it with the shaft horizontal, and adding weights or removing metal until it showed no preference for taking up any particular position, but that would be approximate at best…?

[AndyfParticipant @andyf]

One way would be to put it on a longish and hopefully straight bar between bearings of some sort, then rev it up slowly (perhaps using an electric drill). If it's out of balance, the bar will flex towards the heavy side, and a felt-tipped pen mounted close to the wheel when static will mark it to show where weight should be removed. This would need a number of iterations at gradually increasing speeds, and a supply of different coloured felt tips so you can tell new marks from old.

Andy

[Graham RounceParticipant @grahamrounce14492]

Hi Andy – Past a certain speed the bar is going to bow anyway, but it sounds worth a try – hopefully it won’t need to go up to that speed.. Now I wish I had a continuous speed control on the drill press! (Or a less heavy duty one of those amazing machines that garages use for car wheel balancing.)

Latest: The metal pipe supplier doesn’t want to cut thin slices, unfortunately.

[TerrydParticipant @terryd72465]

Posted by Graham Rounce on 12/11/2012 14:19:58:
Ian – thanks for all that. I think I'll be using the hopefully precision-drilled-to-3.18mm Meccano bush wheel for the hub – I haven't heard back from him/them yet.

Any tips for balancing it? I was thinking of "hanging" it with the shaft horizontal, and adding weights or removing metal until it showed no preference for taking up any particular position, but that would be approximate at best…?

Hi Graham,

The standard way to balance is to insert a short close fitting bar into the hub and let it roll naturally on 'two razor' parallel edge supports, add small weights or drill out material from the rim to balance. If you drill out too much add lead shot into your drilled hole. I had two tyres fitted today on to my car and the balance machine was amazing – you could use one of those

Regards

Terry

Edited By Terryd on 12/11/2012 21:50:23

[Les Jones 1Participant @lesjones1]

Hi Terry,
Here is a design for a tool to balance model turbine rotors that probably uses the same principal as the car wheel balancing machine.

Les.

[Graham RounceParticipant @grahamrounce14492]

Terry – Yup, that must be the way to go. Thanks.
Les – That’s fantastic. I wish I was as well-directed, quick, single-minded or whatever as him! Most people would count their lives well spent if they successfully completed EITHER of those projects!

[Author]

Posts