Bolt Question

Is what you really want a shoulder screw?

In the larger sizes, it is called a _structural bolt_. They are used in buildings to hold steel together. In smaller sizes bolts like that are used as pivots, like shock mounts on motorcycles. If you just need a few, I'd just get long bolts and saw off most of the threads.

Most 1/4-20 bolts are made with all threads up to about 1 1/2" long, then there is an unthreaded portion with about 1 1/2" of threads as they get longer. Depending on the ammount of unthreaded shank you want, it would be cheaper to buy a bolt with the correct ammount of unthreaded shank and cut off the un-needed threaded part. Cut with a nut on the part you want to keep, running the nut off will help to straighten up the cut threads. This presumes the Home Depot type of hex headed bolt is what you want, and you don't need too many. If you need thousands, then contact a specialty bolt maker and have them made to order. Steve

SteveB wrote in article ...

There are at least two options that come to mind.....

First is a shoulder bolt.

The shoulder bolt is often used as an axle in items such as lawn mowers.

The only problem is that the shank and the threads are usually two different sizes....IOW, a 1/4" shoulder bolt will not have a 1/4" threaded portion, so you may have to go up in shank size - such as 5/16" or 3/8" - if you need a 1/4" threaded portion.

The other option would be to go with a Military specification, AN fastener. These fasteners generally are all shank with a small amount of thread at the end - usually just long enough to mount a locking or castellated nut with a few threads sticking out on the other side.

Your local airport that services virtually any sized plane from Piper Cubs on up to 747s should have an assortment, and might be willing to sell you the size you need.

If they don't have what you need, the local A&P-licensed tech might be able to give you a standardized AN number with which you can order exactly what you need.

An added advantage to AN, MIL-spec fasteners is that - depending upon exactly which series is stocked by your local fixed-base operator - they are likely to be pre-drilled for safety wire.

Bob Paulin - R.A.C.E. Race Car Chassis Analysis & Setup Services

If you get AN bolts (for aircraft), they come in, IIRC, 1/8" increments in length and threaded for only 1/2". If that is still too much thread, you should be able to get the unthreaded length you need. I prefer to cut bolts in the lathe rather than a saw - much cleaner ends.

What are these for? 1/4" threaded length is marginal for a washer and nut.

Ted

The first thing I thought of was shoulder bolts like someone else pointed out but their threaded portion is a different diameter from the rest of the bolt. I knew this had come up before but I couldn't remember the answer until I came back to the question a few hours later and it finally hit me.

Caster bolts. Or caster axles. If you go to

and search for caster axles, then scroll about halfway down the page you'll see them. They don't quite go down to only 1/4" of threads though.

Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com

"Even if you are on the right track, you'll get run over if you just sit there." - Will Rogers (1879-1935).

Hey Steve,

Look up aircraft suppliers. The bolts designated "ANxx" have what I think you want. B-U-T---- they only come 1/4-28. In any event, the terminology is "length" and "grip length", where length is the overall or as you would measure any bolt/screw, and where grip is the unthreaded part. None of this to be confused with a "shoulder bolt", which has a different main shaft size versus the threaded portion size.

Take care.

Brian Laws>SteveB wrote:

No, what he really wants is a screw with a grip. It may be possible to buy the proper length of grip, then remove the excessive threaded portion.

Harold