| Subject: Re: Machine Screws (update, and SUCCESS) |
Author:
Mike
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Date Posted: 20:01:53 12/18/15 Fri
In reply to:
Jon
's message, "Machine Screws" on 19:45:48 12/13/15 Sun
I'd be willing to bet that the drawer pulls/knobs you have were manufactured in England and have British Whitworth thread metal inserts.
The US #8 screw diameter is either 0.160 or 0.162 inch depending on which book you read. The Whitworth 3/16" size is based on a body diameter of 0.1608 at 24 threads per inch. The Whitworth 7/32" size is based on a diameter of 0.1654 inch also at 24 TPI, but that's a little large for 0.160......
A good start would be to call British Tools & Fasteners supply at 315-946-9400, or check out their web site at
http://britishfasteners.com (but the web site doesn't have everything, call them).
A quick look at their web site using a search for 3/16
(http://britishfasteners.com/catalogsearch/result/?q=3%2F16)
finds a variety of 3/16-24 Whitworth screws in a number of heads, lengths and materials.
I'd buy one each of a 3/16-24 screw and a 7/32-24 screw and see which is a better fit for your drawer pulls.
None of the screws I found on the web site have shoulders, you may need to add a washer under the screw head as a substitute.
Note that Whitworth sizes are different than US sizes. In the US system the number stamped on the wrench or socket is the measurement across the flats of the hexagonal bolt head or nut. Whitworth wrench sizes indicate the diameter of the threaded part of the bolt, i.e., a wrench required for a 1/4 Whitworth bolt will have "1/4W" stamped on it.
Another note - some of the screws that British Fasteners sells have "Posidrive" heads. These look like Phillips heads, but from experience I can say that a Phillips screwdriver will work in a Posidrive head, but with any amount of torque it will twist out and damage the head.
If you purchase Posidrive screws PLEASE acquire a Posidrive screwdriver to go with them.
I've run into a lot of Posidrive damage in my volunteer work with Red Cross two way radios - Posidrive was used extensively in the manufacturers automated assembly (that's what it was developed for), and during the service life the local radio techs use Phillips head tools in their bench repair - the fasteners look like Phillips, a Phillips screwdriver fits, so they use it.
Then 10 to 15 to 20 years later the Red Cross inherits the decommissioned radios and our group gets to bring them back to life for Red Cross volunteers to use, and I get to replace a lot of damaged fasteners.
As far as finding actual US size 8 fasteners at 24 threads per inch....
I called the local "big three" industrial suppliers in the USA (Grainger, McMaster Carr and MSC Supply - also known as MSC Industrial or MSC Direct) and also a couple of local specialty suppliers... a gunsmiths supply, and a aircraft supply. No luck anywhere for 8-24 screws or bolts (any head style), or threaded rod (all-thread).
If you can't find the actual screw you need, there is another option, but it will require a bit of work...
I did find 8-24 taps and dies however... Ababa Bolt in El Cajon (south of Can Diego, California) at 619-440-1781 (ask for Yon Rasmussen) claims to have both taps and dies available in US size 8-24...
The tap is part number A1S-121-00824 at $17.83 each, and the die is part number A1S-100-00824 at $28.33 each.
So if you get a die and some rod stock then you can make your own allthread, then cut it to length, weld a 1/4 inch piece of hex stock and a washer to one end of each piece, insert the thread area in the hole from the back side, then screw the knob onto it. The piece of hex stock is your bolt head.
Yes, making your own is a lot of work, and I think your best bet is to pursue purchasing some Whitworth screws.
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