Securing threaded backplate

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John Stevenson on 24/02/2017 21:45:03:

…

(a) I presume that is the sarky bit but if you read it it makes perfect sense on an engineering forum unlike a milking stool.

…

(b) All I was pointing out in reply to whoever posted the picture of the Hemingway kit back plate, was that 4 is easier than 3.

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< letters added for ease of reference >

(a) … Yes it makes sense IF you are talking about clamping forces, but it was irrelevant to the adjusters on the GripTru … [whereas the milking stool is relevant, for the reasons I have explained]

(b) … and all I was pointing out was that although 4 is easier than 3, it is also less reliably accurate.

MichaelG.

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P.S. … for anyone who might actually be interested in reading a little about kinematics

https://dspace.mit.edu/openaccess-disseminate/1721.1/69013

 

Edited By Michael Gilligan on 24/02/2017 22:19:01

[John Stevenson 1Participant @johnstevenson1]

Posted by Michael Gilligan on 24/02/2017 22:12:12:

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(b) … and all I was pointing out was that although 4 is easier than 3, it is also less reliably accurate.

MichaelG.

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Utter Tosh.

 

How can an adjustable back plate with three screws adjusted to 0.0001" run out be more "reliably accurate"  that one with 4 screws also adjusted to 0.0001"

 

End result is the same, all that differs is most PRACTICAL people will get on with 4 screws better than 3.

Edited By John Stevenson on 24/02/2017 22:16:59

Edited By John Stevenson on 24/02/2017 22:30:15

[Michael GilliganParticipant @michaelgilligan61133]

< no further comment on this >

Edited By Michael Gilligan on 24/02/2017 22:29:27

[Howard LewisParticipant @howardlewis46836]

Milking maids, or their 3 legged stools, are barred from my shop! (says he sheepishly)

But to be serious for a few seconds.

My oriental lathe with screw fitted chucks uses two clamps fixed to the back of the chuck to hook behind a chamfered flange on the mandrel, to prevent the chuck going AWOL when running in reverse..

Suggestion for the brave and innovative.

IF you could make up a split ring, with a chamfer on the back face, and clamp it to the plain dia behind the register, maybe a couple of "hooks" could be attached to the back of the chuck, to prevent the chuck unscrewing on the odd occasions when you run in reverse.

Drill/tap two largish dia shouldered "studs" into the backplate, on a diameter, and tap the outer end of the shoulder, radially, to take the screw fixing the "hooks"?

When I had a ML7, it lacked this feature, but by GENTLY tightening the belt, and taking light cuts, (never tried screwcutting – where the cuts are likely to be heavier) it was possible to run in reverse without the chuck coming loose. Maybe I was just lucky.

Howard

[Martin KyteParticipant @martinkyte99762]

What is all this 3 legged nonsense anyway.

In a griptru chuck you cannot adjust anything unless all the adjusters are backed off. One is then turned to shove the chuck body along the adjustment axis. The chuck is still held on the flange by the loosened clamping screws. As far as the adjusters are concerned only one is in play so I guess that makes it a one legged stool.

The basic point is that the chuck is held by pressure from the mounting bolts creating contact points on the flange. It makes no difference how many bolts you fit, in fact you could put just one through the middle and it would still be stable.

regards Martin

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 24/02/2017 22:19:48:

< no further comment on this >

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