RE: [CAD_CAM_EDM_DRO] fastener thread pitch choice

It is true that a fine thread fastener is stronger, because the root diameter is larger.

It is also true that you get more mechanical advantage using fine threads-they will be "tighter" with the same amount of torque used on the screwdriver or wrench.

It is also true that fine threads will more easily pull out of softer materials-that's why studs used in engines commonly have 2 different threads-a coarse one that screws into the casting, whether it is cast iron or aluminum-and a fine thread for the nut at the other end.

______________________________________
Andy Wander

-----Original Message-----
From: CAD_CAM_EDM_DRO@yahoogroups.com [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of H & J Johnson
Sent: Sunday, July 12, 2009 7:28 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] fastener thread pitch choice

I would think that in the smaller size screws the more important aspect would be to make sure they are all the same.. having different thread pitches in the same machine for the same size screw is just a receipe for disaster..

Fwiw

J. Johnson

> Thsnks Jack,
> I'm building a 4 by 8 foot router, I've got a mix of fine thread
> and coarse
> thread fasteners so far. Are there definite advantages of using
> the fine thread
> over the coarse? I think the fine thread won't tend to loosen.
> Also, perhaps
> the fine threads and are stronger because less material is removed
> when cutting
> the thread and the root diameter of the external thread is larger
> than coarse
> thread fasteners. What's your opinion on these 2 points?
> cheers,
> Denis

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