Super 7 motor pulley

[mike mcdermidParticipant @mikemcdermid41977]

I have one further question

It seems the new older super 7 has an incorrect pulley,For those not having read my previous post on the clutch its the early super 7 with the cast in oil reservoir in the headstock

The motor shaft is half inch not 5/8" as on the later one and the odd thing is one of the dual speed pulleys seems to be correct ,the small diameter not the larger will keep the belt tensioned but the larger is nearly 3-1/2" diameter and the belt is basically flapping in the wind by a long long way,the countershaft pulley is correct though judging from photos,

I dont think this is correct motor pulley and the other myford i have has a different set of pulleys all together so im unable to reference

Does anyone have an idea what pulley i need Myford /RDG only have 5/8 pulleys so cannot supply one to be honest

i like this old machine its got character and a headtock spindle which is indicates at 0.0002 so im thinking its not bad for a 62 year old machine

Once again thanks for the help

[mike mcdermidParticipant @mikemcdermid41977]

[sparky mikeParticipant @sparkymike]

I too have a very early super 7, around 1952/3, but my motor shaft is 5/8" diameter. Could it be possible that the motor has been changed for whatever was on hand and likewise the pulley. Incidently, I have to replace the motor pulley before I can finish the rebuild on my lathe, but this seems to be a little different to the one currently on offer by RDG. It is also made in alloy. Looking at the new one, that looks like cast iron ?

The overal diameters of the pulleys are 4 5/16" and 1 7/8". How are pulleys normally measured? Bottom of groove, or over the top?

Mike.

[sparky mikeParticipant @sparkymike]

Continuing on the same subject, I find that the countershaft to headstock drive belt is an "A" section but the motor to countershaft belt would seem to be smaller, ie. a "Z" section.

Is this correct?

Mike.

[DMRParticipant @dmr]

Mike Mc,
I have the 710th production S7 and a more modern one. To my certain knowledge Myford never fitted motors with 1/2" shafts.
I would have to agree with Mike that it has been changed along with the pulley. What does the motor plate say as to manufacturer? Might give you a clue.

Sparky Mike,
The belt sections are different. Countershaft to spindle is A29 1/2 (A29 and a half). Motor to Countershaft is M32 1/2.

FYI early motor pulleys were alloy but at some point an iron one was made available as a spare. The small (inner-slow speed) tended to wear out rapidly.
At some other point or maybe the same time, Myford began fitting iron motor pulleys as standard.
Later still, probably when stocks of alloy pulleys ran out, Myford announced that they would no longer supply the (cheaper) alloy pulley. At a guess, that was before the year 2000.

Dennis

[RobboParticipant @robbo]

I have an older S7, from 1954, which has the original aluminium pulleys. As Dennis says, Myford have always used motors with a 5/8" shaft, so it has been changed at some time – not surprisingly- I also have a more modern motor fitted, but still with a 5/8" shaft, as this is the bore size of the original pulley.

My later S7, from 1967, still has the aluminium pulley.

The diameters of the original motor pulley are 45/16" (four and five sixteenths),so yours is a bit small, and 17/8" (one and seven eighths), as I said the bore is 5/8".

If you can get pulleys the right size you can always sleeve the bore to fit your motor – or fill it up and re-bore.

Also as Dennis says, the belt sections are different, the motor to countershaft being slimmer than the countershaft to headstock.

Hope this helps

Phil

 

Edited By Robbo on 08/09/2012 22:29:56

[sparky mikeParticipant @sparkymike]

My motor has the 5/8" shaft and is a Gryphon make. I don't know if this is original or not as it is not resiliently mounted , which I understnd all Myford motors were, or perhaps early models like mine just had whatever was available at that time, and the quieter motors were phased in at a later date.

On the motor nameplate in the "Type" box, are the letters PROT. … Prototype ?? I can't think what else this could stand for.

Mike.

[RobboParticipant @robbo]

Forgot to mention in previous post that pulleysare measured across the outside diameter, not in the groove.

Phil

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