Spanner Head Hole Dimensions? 2

[balloon]

Hello!

I am designing a fastener that I'd like to use a #4 spanner head screw drive on, but cannot find any documentation around what diameter to make the holes.

I found this document from Fastenal that lists all the dimensions and tolerances I need except for the diameter:

https://www.fastenal.com/content/product_specifications/MS.PSPAN.SS.pdf

It just lists "Drive Size" as "4," does this relate to a standard dimension that I should know?

I looked up the normal width of #4 slotted and Phillips and it looks like they are .031" - .039" wide. I also am ordering a some spanner head screws from McMaster to measure myself, but would feel better if I could find a reference or standard to back that up.

Thank you!

 

[drawoh]

balloon,

Are those security drive based on a standard, or are they proprietary? Can you contact the manufacturer of the driver?

--
JHG

 

[berkshire]

This is an area where the screw manufactures are a bit cagey, and do not like to give out this info for security reasons. In fact some makers will custom manufacture snake eye screws to your specs.
It may be better to work backwards and buy a driver bit first and reverse engineer it.
On the link I provided, scroll down to Bits Only and select one there ( Even there you will notice there are no given dimensions.)

B.E.

You are judged not by what you know, but by what you can do.

 

[Artisi]

Did you ask the manufacturer?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[balloon]

Hi everyone, thank you for the quick replies!

I know there is a proprietary "snake eyes" brand (by "Tamper Proof," the company berkshire linked to), but there are also lots of generic "spanner head" drives on the market. I was hoping these generics were standardized and I was just missing the documentation.

I've avoided contacting the manufacturer thus far because I suspect, like berkshire mentioned, they'd get a bit cagey.

I have ordered a "#4" driver bit and a set of "#4 spanner head" machine screws to measure. My only concern with this route was coming up with the proper tolerances given the small sample size. For my application, the smaller the holes, the better, but I'd also like to ensure the driver fits the screw the vast majority of the time.

Thank you all for your help! I think the reverse engineering route is the way to go, and I'll also get in touch with a couple manufacturers. It can't hurt to ask!

 

[Screwman1]

Just put on the drawing #4 spanner head and let the fastener maker do his thing- you'll get correct parts. You are right; we don't like to publish the exact dimensions to keep at least a modicum of security to the screws. The worst prints that we see are where customers have tried to self define fastener recesses- they put down what they think are the tolerances from their reverse engineering job and that is all dependent on how their basis parts were made. A good portion of the time we have to go back and gently tell them that their part can't be made to the print because it has a non-standard recess.
We have all the standard and specs for the various drives- in this case I would just call up our punch manufactures and order #4 spanner drive punches and they would just send them out- no need for any dimensions at all. Just like you don't need to dimension a #2 Phillips- just tell us what drive size you want.

 

[balloon]

Hi Screwman1,

Thank you very much for the reply! It's great to hear from someone specifically in the industry.

I totally agree, I'd much rather leave it up to the supplier and not get involved in the details. Unfortunately, the component I'm designing is non-standard for numerous other reasons, so we're working with a machine shop that doesn't normally produce these sort of things and, I believe, wants specific dimensions for every feature. This might be a an invalid assumption on my part, however. They very well may be able to order a punch like you suggest and I'm just overthinking it. I'll look into that route!

Thanks again to everyone for all the assistance!

 

[KENAT]

So Screwman1, how do you customers verify the parts came in correct?

From an IP point of view I get what you're saying, from an inspection point of view seems to leave a gap.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[Screwman1]

They would use a drive bit as a functional gage. Similar to how a Torx recess is gaged, not measured.

 

[KENAT]

Well it's questionable to use any old bit as as an inspection gage, but I guess somewhere probably sells something suitable.

http://greensladeandcompany.com/fas.../recess-head-gaging/recess-penetration-gages/

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[Screwman1]

Greenslade, Universal Punch, Wrentham, etc., they all make drive bit elements for gaging use.