Longer Machine Screw 1

[Tofflemire]

Hi All,

Do any you know if and where I can purchase some 6-32 stainless Steel 3.5" screws long. From my inquiries it appears that 3.0" is the longest you can buy in that thread size.

My next question, does anyone know how to stretch 6-32 screws about .040". My problem is that I have purchased 3 batches of 6-32 SS x 3.0" but the tolerance is +/- .09 on 3" screws. When I measure these screws most of the screws are .07 short but still in spec. This .07" works out to be about 2-3 threads that I must have. I can not change my parts that I made because it is for a military group, and to do so would take a long time and larger amounts of money.

Just to give you all heads up if you do not already know this, from my experience screws that are over 1.5" long the manufacturer makes the length on the short side of nominal but still in tolerance.

Tofflemire

 

[Screwman]

Toffle,
If you contact any major manufacturer they will gladly make you those parts in the lenght that you need. You will likely have to pay a lot charge to have them made to your requirements, but then you will be able to specify the exact length tolerance tht you need for the parts.

The only way to 'stretch' those screws will be to load them up past the yeild point. This will cause the thread pitch length to change and you will likely end up with parts that will no logner pass thread gaging requirements. Don't try to stretch them...Bad Idea.

 

[MintJulep]

Nor will your customer appreciate "special" standard screws.

 

[unclesyd]

You maybe in luck very similar fasteners are being supplied routinely.

You might contact Mike Jones at:

http://www.ameribolt.com/

 

[MikeHalloran]

Getting 'short' parts that are still within tolerance is not unique to screw lengths.

The practice is also commonplace in metals and plastics; when you buy to a stock size/thickness, the stock is always on the low side of the commercial tolerance. Of course they always charge you for the full thickness.

Re stretching the screws, if they have a plain shank, you might be able to roll it to a smaller diameter. It's got to be much easier to just buy exactly what you want.




Mike Halloran
Pembroke Pines, FL, USA

 

[Tofflemire]

Hi All,

Thank you all for your input. I agree with all of you. We made a decision to change from 3" ss to 3.5 steel and cut to our required length. This is the only way to ensure we get what we want, like MjintJulep states "Nor will your customer appreciate "special" standard screws". We did find out from our customer that we could still change without causing to much paper work.

Tofflemire

 

[MikeHalloran]

Were I your customer, I'd probably prefer that you get rid of such a long skinny screw, the middle 90 pct of which does nothing. And I'd greatly prefer you to use _any_ thread other than 6-32, which is notoriously weak in any alloy.



Mike Halloran
Pembroke Pines, FL, USA

 

[Tofflemire]

Hi Mike,

Once again, I agree with your statement. In my case, were were machining 2 pieces (out sourced) to bolt together, if we were to machine a deeper pocket the cost to due so would be higher. The other factor to consider is there is not much forces acting on my 2 parts, it was more a precaution, similar to a remote control that snaps together, but there is still the odd screw to prevent it from popping apart if dropped.

Tofflemire

 

[Sparweb]

This may do; from ASSIST:

http://assist.daps.dla.mil/eAccess/...689EBD&s_key=D8EFC3CD292C011253FD93D9763EBC02

Click on the "Revision H" version.



Steven Fahey, CET