MYFORD SUPER 7 HEADSTOCK

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MYFORD SUPER 7 HEADSTOCK

This topic has 10 replies, 6 voices, and was last updated 29 September 2011 at 00:14 by ady.

Viewing 11 posts - 1 through 11 (of 11 total)

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28 September 2011 at 12:16 #75505
neil mackay
Participant
@neilmackay21172
I am rebuilding a myford super 7 circa 1976. The bed has been

reground and I am refitting the headstock. Does anyone

on the forum have data on the correct torque setting for

tightening the four M8 x1.25 x 25mm socket cap screws which

close the headstock onto the cast iron bed?

Any information would be most appreciated.

Many thanks

Edited By David Clark 1 on 28/09/2011 12:31:27
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28 September 2011 at 12:16 #21939
neil mackay
Participant
@neilmackay21172
TORQUE DOWN SETTING
28 September 2011 at 15:46 #75510
KWIL
Participant
@kwil
I have never needed to torque them down when rebuilding but my fingers tell me when, I could measure one I suppose.

Another point, was the saddle ground as well? If not you will need to be very particular when setting up the leadscrew etc.
28 September 2011 at 16:36 #75511
neil mackay
Participant
@neilmackay21172
Thank you very much Kwil for your prompt reply. Yes the saddle was reground and fitted by a Myford fitter one of the last ones to be done before Myford sadly went out of business!

Ive re- fitted the apron and lead screw with no problems. I dont want to strip the threads

in the cast iron but would like them to be as tight as possible so if you could give me

a test figure without too much trouble this would be most helpfull. My fingers are not

as good as they used to be as I suffer from arthritis!

Best Regards, Neil
28 September 2011 at 16:45 #75512
Richard Parsons
Participant
@richardparsons61721
Neil,

First of all I would use a very thin smear of engineer’s blue (not marking out blue) and do a trial fit to the lathe bed. If the fit is less than 85% get the Headstock base reground as well.

Second get a nice straight bar just pinch up the headstock and with a sensitive DTI check that the bar is parallel to the bed OK if not well think about the use of a scraper.

Torque the bolts up by hand slowly in a star pattern leaving about 15 minutes between each tightening for the stresses to come out. Use a thin smear of oil on the bed when you do it.

There are no values in my Super 7 hand book (am I allowed to mention this by the new owners?)
RGDS

Dick
28 September 2011 at 17:17 #75514
neil mackay
Participant
@neilmackay21172
Dear Dick,

Thanks for your reply. I have checked with a dial indicator with the head bolts

pinched down and I am getting a reading of 0.0002″ over 4″ on a test bar parallel to

the bedways so I hope this will be OK!

Best Wishes, Neil
28 September 2011 at 17:26 #75515
Clive Hartland
Participant
@clivehartland94829
Neil, nip the bolts to about 5ft lb and then tighten to 12ft lb and then finally 20 – 22ft lb.

Criss cross between the bolts to even the load as you tighten.

There is no need to wait between tightening sequences, do not lubricate the bolts but put thin grease or oil on bed beneath the headstock. This will stop cutting fluids migrating under the head.

These are nominal figures for 8M x 1.25

Clive
28 September 2011 at 17:43 #75516
Tony Pratt 1
Participant
@tonypratt1
Hi Neil, .0002″ over 4″ is I would think very very good and completely acceptable!

Tony
28 September 2011 at 19:28 #75520
KWIL
Participant
@kwil
Neil,

By my fingers and then tested with a torque wrench 12 lbs. ft / 15 Nm.

Looking at the torque wrench charts for 5/16″ BSF (8mm approx) they give 11.7 Lbs. ft. for a 20 ton tensile bolt, which I would use as OK.

Regards

K
28 September 2011 at 20:03 #75523
neil mackay
Participant
@neilmackay21172
The information and advice is all very much appreciated. Thanks for all the new

contributions from Kwil, Clive and Tony.

Cheers, Neil
29 September 2011 at 00:14 #75531
ady
Participant
@ady
I wouldn’t get too hung up on the setup until I started chopping metal up.

Tie it down and then see what you can do with it.
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