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.DXF Files for Meccano Chain Wheels

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Steve Withnell24/10/2020 18:11:16
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Where can I get hold of meccano chain wheel drawings in .dxf format ?

I have an old radio that using rubber drive belts for part of the tuning mechanism and they perish very quickly, as they get cooked by the valves.

Meccano chain drives would look neat and be a long lasting solution.

TIA

Steve

Steviegtr24/10/2020 18:18:33
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Dad used to use elastic bands. Usually worked.

Steve.

not done it yet24/10/2020 18:20:39
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Use nitrile instead?

JasonB24/10/2020 18:26:56
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If you have CAD then you could draw them up from this

Jeff Dayman24/10/2020 18:46:04
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Seems to me I have seen some radio tuners on old radio equipment (maybe ex Canadian Army from ww2 era) using a thin wire rope like a bicycle brake cable. The wire rope was fixed with a clip to each rotating drum, and each drum had a few turns. The wire rope ends were terminated with eyes which held an extension spring to keep rope tight on drums and take up any play from heat expansion, rope relaxation, bushing wear, etc.

Meccano chain as you suggested would probably work great too. if the items to be coupled make the chain move less than the span between them plus the length of an extension spring, you might be able to use an extension spring to take up any slack in the chain and keep the chain snug on the sprockets. Just food for thought.

Michael Gilligan24/10/2020 18:46:58
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Posted by JasonB on 24/10/2020 18:26:56:

If you have CAD then you could draw them up from this

.

Nicely drawn, that yes

Lessons could should be learned

MichaelG.

Grindstone Cowboy24/10/2020 19:00:40
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Posted by Jeff Dayman on 24/10/2020 18:46:04:

Seems to me I have seen some radio tuners on old radio equipment (maybe ex Canadian Army from ww2 era) using a thin wire rope like a bicycle brake cable.

Radio dial cord, like this - used to be available from such suppliers as Maplins.

Rob

JasonB24/10/2020 19:02:45
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I just learnt thiswink 2

mec gear.jpg

Bazyle24/10/2020 19:15:00
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Just for general interest. Meccano did not design the chain and sprockets for themselves. They just used ones that were in mass production already for the drive in player pianos.

Martin Cargill24/10/2020 19:16:18
148 forum posts

What about using Mammod style spring drive belts? or if smaller ones are required the springs from the back of shaft oil seals.

Martin

Bazyle24/10/2020 22:11:06
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That link to the Meccano drawings is realy interesting. In looking at some of the gears and wheels I see they use the word 'pummel' as a noun for the boss. This is not mentioned in the online dictionaries I checked, most not even acknowledging a noun and only wanting to recognise 'pommel'.

Michael Gilligan24/10/2020 22:25:32
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Posted by JasonB on 24/10/2020 19:02:45:

I just learnt thiswink 2

.

I didn’t mean you, Jason ... I was thinking more of a recent ‘reworking’ fiasco

The Meccano drawing is a model of clarity, and remains useable

MichaelG.

JasonB25/10/2020 06:28:26
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Yes everything is on the drawing *, the only thing I had to make a call on was whether the 0.015" was a straight line between where the two arcs meet the OD or if it were the length of the small arc, though it would not make much difference on such a small dimension. I did learn a little as it made me think how best to draw it and did use one option that I don't use often. I'm just waiting for Dave's pencil drawn on nowsmile p

* :Looking again I see it was steel and I coloured it for brassblush

SillyOldDuffer25/10/2020 11:49:48
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Posted by JasonB on 25/10/2020 06:28:26:

Yes everything is on the drawing *, the only thing I had to make a call on was whether the 0.015" was a straight line between where the two arcs meet the OD or if it were the length of the small arc, though it would not make much difference on such a small dimension. I did learn a little as it made me think how best to draw it and did use one option that I don't use often. I'm just waiting for Dave's pencil drawn on nowsmile p

...

I learned from this one too. My attempt in Qcad:

wrongmeccano.jpg

It's wrong! Right at the beginning I misplaced the tooth valley by centring its radius on the pitch radius circle, which is not what Meccano Ltd drew.

I looked 'Pummel' up in my big dictionary. Must have been old-fashioned in 1944 because it's an archaic spelling of 'Pommel', which includes the meaning 'boss'. Pommel and pummel are interesting. To pummel is to beat, and the pommel of a medieval sword (the round ball on the end of the handle),  is used to balance the blade and hammer people.

Dave

Edited By SillyOldDuffer on 25/10/2020 12:10:07

JasonB25/10/2020 12:23:59
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Was the boss fixed to the sprocket by expanding the end Pummel "beat" may be appropriate

blowlamp25/10/2020 12:36:51
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Here's mine in MoI.

Martin.

meccanoline.jpg

Steve Withnell26/10/2020 16:58:02
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Posted by JasonB on 24/10/2020 18:26:56:

If you have CAD then you could draw them up from this

Thanks Jason, helpful as ever.

Much appreciated.

Steve

Engine Builder26/10/2020 17:59:54
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This site has all the Meccano original part drawings. I have made some parts using them.

Meccano Drawings

Steve Withnell27/10/2020 12:10:31
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Started drawing my version - thing I can't work out is how to establish the centre for the 0.125inch radius? The valley and 'flat' on the tooth I can work out, but finding the centre is defeating me!

Regards

Steve

JasonB27/10/2020 12:17:12
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I did not find it but could measure from my drawing. I drew a 0.250dia circle and made it tangental to the 0.046" one for the valley and then also made it pass through (coincident) one end of the 0.015" arc.

Edited By JasonB on 27/10/2020 12:21:12

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