Talk about a head scratcher! I finally asked one of the engineers why and they said per thousand the 10-24 were about $.20 cents cheaper verses the 10-32. Millions of fasteners and not a single 10-24 stocked, SHCS, FHCS, SSS, RHMS, etc and notta single 24TPI in anything unless special ordered and then it had to be case quantity.įast forward to now and we've been doing the finishing machine work on the facial recognition camera housings for Walmart and some genius decided the 4 holes that close the camera housings are 10-24 x 3/4 SHCS yet the mounting pads for the electronic boards are 4mm. My industrial supply in Tennessee had around 10,000 SF dedicated to fastener warehousing for Rockford®, Unbrako®, Allen® and a hand full of the cheaper brands. I never really could figure out why 10-24 just wasn't that popular. Even those mounting rails that I mentioned above are normally made from sheet metal, rolled to shape. Thicker castings are quite rare in this type of equipment. It is desirable to have more than one full thread in a hole and many of the professional style, electronic devices were constructed with sheet metal. One possible reason for the use of fine threads is the predominance of sheet metal over thicker castings. I do not think this was the original reason for 10-32s, but it is interesting.

However, they would not fit through a 10-24 hole if the standard #25 (0.1495') tap drill was used. The M4s had a nominal OD of 0.1575' and would fit through a 10-32 hole if a #21 (0.159') tap drill was used. One curious thing that I have seen is some equipment from other countries (metric countries) came with M4 screws and nut plates that fit behind a set of three 10-32 holes in the rails. And you could order non-standard mounting rails with the 10-24 threads, but almost no one ever did. I am not aware of how this usage started in professional electronics. There are many other examples of fine threads being used in professional, electronic equipment. Those mounting screws are usually a combination of an oval head with an integral imitation of a countersunk washer to provide a wider head to better grip the usually slotted holes in the equipment being mounted. We would buy the mounting screws by boxes of 1000. Only one example is the mounting rails in standard electronic racks almost always have 10-32 holes. But 10-32s are used all over in electronics. I come from a professional electronics/radio/TV background and I almost never saw a 10-24 in use there.

T slot bolts 1032