Shopsmith Forums

Here's the direct excerpt from mark V manual:

"Note the base lock is slightly off center to the countersink found in the bench base, as shown in Figure B-48. This offset allows the base lock to more firmly hold the base in place."

Just out of curiosity, how in the world "This offset allows the base lock to more firmly hold the base in place".

I do not want to bring a basic science intuition, but what am I missing here?

It keeps constant pressure on the threads to prevent the bolt from loosening.
Bill V

Thanks for the quick answer.
If that's the case, why wouldn't they align the slope of bolt tip to the slope of the tapered hole to maximize the contact surface? I guess it may be the old trade secret in the industry???

wa2crk wrote:It keeps constant pressure on the threads to prevent the bolt from loosening.
Bill V

Now how long will it take you to notice that the upright position is not at 90 degrees to the base?

As the seconds tick by....................

Ed

jjj240 wrote:Thanks for the quick answer.
If that's the case, why wouldn't they align the slope of bolt tip to the slope of the tapered hole to maximize the contact surface? I guess it may be the old trade secret in the industry???

wa2crk wrote:It keeps constant pressure on the threads to prevent the bolt from loosening.
Bill V

It is not the friction of the bolt tip to the base casting. It is that the offset puts lateral pressure on the bolt which puts pressure on the threads. Having said that, I don't know why having the bolt centered and putting inline pressure on the threads would not do the same thing.

Might be a case of that is the way Magna originally designed it, it's not broke so why fix it.

Ohh... I did NOT know that...
learning is good, always

reible wrote:Now how long will it take you to notice that the upright position is not at 90 degrees to the base?

As the seconds tick by....................

Ed

jsburger wrote:

jjj240 wrote:Thanks for the quick answer.
If that's the case, why wouldn't they align the slope of bolt tip to the slope of the tapered hole to maximize the contact surface? I guess it may be the old trade secret in the industry???

wa2crk wrote:It keeps constant pressure on the threads to prevent the bolt from loosening.
Bill V

It is not the friction of the bolt tip to the base casting. It is that the offset puts lateral pressure on the bolt which puts pressure on the threads. Having said that, I don't know why having the bolt centered and putting inline pressure on the threads would not do the same thing.

Might be a case of that is the way Magna originally designed it, it's not broke so why fix it.

OK. Now, I start to understand better.
Thanks!!!

It is very basic mechanics. Look at the bolt and the hole. Both of them are tapered. Centering it would allow it to wobble unless both of them were exactly the same size and shape. Any wear on either one would allow it to wobble even if they were originally made the same size.
By offsetting it a bit, the tapered bolt locks securely against one side of the taper of the hole allowing no movement.

This is why some people score high in mechanical aptitude tests and others don't. The guy who designed it is one of those high scorers.

garys wrote:It is very basic mechanics. Look at the bolt and the hole. Both of them are tapered. Centering it would allow it to wobble unless both of them were exactly the same size and shape. Any wear on either one would allow it to wobble even if they were originally made the same size.
By offsetting it a bit, the tapered bolt locks securely against one side of the taper of the hole allowing no movement.

This is why some people score high in mechanical aptitude tests and others don't. The guy who designed it is one of those high scorers.

Well said

A common point of thinking it is a 'defect'.(the hole is not centered......)

The design is a very 'simple'(effective) way to prevent accidental falling of the headstock etc. back to horizontal. It is also simply manufactured.




The only problem with it is we dinosaurs can forget to loosen it when intending to lower it back down(as evidenced by some pictures posted within this forum).

If you're familiar with a drawbore joint, it's the same principle.