Screw Sizes

[Incubus]

My Quadraverb GT uses screws to hold the top and bottom covers which are the same thread as the ones normally used to hold the covers on computer cases.

From what I can see on the net, the thread size is something called 6-32. My reference for that is here:

http://www.maplin.co.uk/Module.aspx?ModuleNo=32094&doy=16m1&C=SO&U=strat15

The thing is, I'm in Australia and I don't understand what that means....is it a number 6 screw that has 32 threads per inch ?

The diamater of the screws is about 3.5mm.

I figure there is no metric equivalent, so does anyone know where I can find this size ?

I went to bunnings and bought 6G screws that I needed for something else (self tappers) and I thought that if the diameter is the same, the thread must be the same, but they aren't.

Any help much appreciated.

[grapefruit]

Howdy,

It's annoying to those of us in the metric world that most american audio equip manufacturers still use imperial machine thread screws. I doubt that the thread would be the same as PC case screws. I've tried them before for various US built audio gear.

Your best bet would be to take one of the screws to a dedicated fastener (bolt) supplier. They can use vernier calipers to measure the diameter and should be able to work out the screw diameter and thread size. You may have to go to a couple of places.

The other option is try and find a written off piece of gear from the US that you can "steal" screws from. From your description it sounds like the same size screw used in DBX gear. Come to think of it, we used to modify DBX266KL compressors so that the front panel controls were moved to the inside, and we had one screw left over for each unit. If you don't have any joy getting them locally I could see if we still have some. I'm in Brisbane...

Cheers,
Stew.

[Paul Perry (Frostwave)]

On the other hand, we are relatively lucky in Australia, because there is a lot of metric AND imperial stuff here.
Places that supply model rail, air and car stuff are a likely source of parts.
For example, in Perth, http://www.mashobbies.com.au/mashobbies/content/products/category_sub.aspx?intProductCategoryID=148

[George Giblet]

It will make more sense if you read the section "Unified Thread Standard" on wiki,

http://en.wikipedia.org/wiki/Screw

#6 implies a thread diameter of 6 * 0.013" + 0.06"  = 0.138" = 3.5052mm which agrees with your measurement
32 = 32 threads per inch.

Then there's the question whether it's a coarse or fine thread.  I think this table has both,

http://www.engineersedge.com/screw_threads_chart.htm

I doubt a metric sub going to work.

[R.G.]

A metric sub will NOT work well.

It's annoying to those of us in the metric world that most american audio equip manufacturers still use imperial machine thread screws.

You don't say! Gosh, think how annoying it would be to have to change from the metric system you use now to Imperial... yep, that's right, keep thinking...   

[Incubus]

I found that my Vox wah also uses the same screws as the Quadraverb, and also the aluminium cases I get from Jaycar uses that size too.

With my aluminium cases and the wah, I've re-tapped the holes to 5/32 size and was able to get screws from Bunnings, although the ones they had were longer than I needed. Cutting screws and trying to clean them up correctly with a file is an adventure.

I'm doing this because I want to mount my pedals to a pedal board and I dont want to just stick velcro to the bottom.

I might just leave the Quadraverb alone for now with it's mix of original screws and computer case screws.

[rikkards]

I too am building a pedal board (got a router for Xmas and had to find a project to work on it) and went through the whole "How do I get them on there without looking like crap". I was thinking of using a large sheet of velcro loops which there is a place on the web that sells a yard for $20 that is 52" long but a guy I work with had a great idea. Use rare earth magnets and a piece of metal that mounts to the board. The problem is the enclosures are not magnetic as they are aluminum but I found that the screws in your typical Hammond 1590BB are. I got rare earth magnets from Lee Valley tools that are about the same size as the screws and it looks like it will work.
The only thing to be concerned about is socketed components as these things are extremely strong. So you would want to ensure that you don't get too strong of ones.
I have yet to really try it out as the board isn't finished. I suspect there may be a bit of movement of a quarter inch or so and I may have to use a bigger magnet and possibly use a magnetic paint but it looks like it might do the job as long as I don't get carried away. Anyways I got my magnets here:
http://www.leevalley.com/hardware/page.aspx?c=1&p=42348&cat=3,42363

warning severe woodworking porn at this link I could spend a lot of money there.

I found that my Vox wah also uses the same screws as the Quadraverb, and also the aluminium cases I get from Jaycar uses that size too.

With my aluminium cases and the wah, I've re-tapped the holes to 5/32 size and was able to get screws from Bunnings, although the ones they had were longer than I needed. Cutting screws and trying to clean them up correctly with a file is an adventure.

I'm doing this because I want to mount my pedals to a pedal board and I dont want to just stick velcro to the bottom.

I might just leave the Quadraverb alone for now with it's mix of original screws and computer case screws.