Re: [CAD_CAM_EDM_DRO] fastener thread pitch choice

Dennis,
 
Really a screw is just a wedge so smaller pitch means greater mechanical advantage.   I think either 10-24 or 10-32 would be more than strong enough for most NEMA 23 stepper motor applications.  A wild guess is that the strength of 4 screws holding on a stepper would easily exceed 1000# in aluminum so isn't an issue.  I think the reason the mfg provide the holes they do is to accomodate proper screw size.
 
My router is only 42" X 16" X 6" work envelope and probably over built using mostly 1/2" and 3/4" cast aluminum tooling plate.  I'm using 4 269oz steppers with ball screws and linear bearings.   I'm making model boat hull patterns and mold plugs. 
 
What do you plan on making with your router?
 
Jack

--- On Sun, 7/12/09, Denis Casserly <denisc1@...> wrote:


From: Denis Casserly <denisc1@...>
Subject: Re: [CAD_CAM_EDM_DRO] fastener thread pitch choice
To: CAD_CAM_EDM_DRO@yahoogroups.com
Date: Sunday, July 12, 2009, 3:38 PM








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

On July 12, 2009 09:19:25 am Jack McKie wrote:
> Hi Dennis,
>
> I used 10-32 in 6061T6 aluminum and tooling plate on both my router and
> mill retro w/o problems. Hope that helps. What are you building?
> Jack
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> --- On Sun, 7/12/09, dcassyc1 <denisc1@telus. net> wrote:
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> From: dcassyc1 <denisc1@telus. net>
> Subject: [CAD_CAM_EDM_ DRO] fastener thread pitch choice
> To: CAD_CAM_EDM_ DRO@yahoogroups. com
> Date: Sunday, July 12, 2009, 12:12 PM
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> Hi Everyone,
> are fine thread 10-32 screws better than 10-24 screws for fasteneing step
> motors on to aluminum machine frame or aluminum gearheads? Can the 10-32
> screw be torqued to the same value as a 10-24 thread? Will the screws hold
> the joint together as tightly? If a steel screw threads into an aluminum
> thread should the threads be coated with an anti sieze compound? I hope
> everyone has a great summer. thanks,
> Denis
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