Billysgoat
The ANTI-BLING!
- Joined
- Apr 21, 2006
- Messages
- 10,694
A flat head screw is not as strong as a hex head is what I've always been told.
The shaft of the bolt is just as strong, yes, the head can be sheared off, but is less likely to shear off than a hex head of the same diameter.
With the stresses on those 3 bolts, I would like to see as much strength as physically possible. + the fact that they are a royal pain in the a$$ if you ever have to remove them. I work on industrial scales, and some scales were spec'd with flathead bolts in certain locations, my experience shows that A. they do not hold their torque as well. B. They tend to gall in their mounting.
Both A and B come down to operator error, if you are using a flat head that you think will need to come out, use never seize or 241 grade loctite.
C. They strip out easily when trying to remove them.
I will agree 100% with this, the allen head used is always one step down from a socket head of the same size, add a little galling and the extra surface contact of the head and you have a problem.
At our shop we have retrofitted every one we have come across to counterbored holes with good old fashioned grade 8 hex head bolts.
The standard for allen head bolts is equal to or above that for grade 8, so you are putting in a weaker fastener, if you have an MSC supply book, look up their info on bolts, good reading.
Current vocation is industrial maintenance, before that was aircraft maintenance, used the stew out of both flat head bolts and rivets. In this application it will actually work better than a hex head, couple of reasons.
1. Greater head contact area, spreads the load out a bit more. Also means the cast plate can be that much stronger by having that much more material around it.
2. You will not be as likely to get the box "Off Square" as easy, the stock box uses threaded holes in the frame for a reason, there is a certain geometry the engineers are looking for and they want the box at angle XY, not angle XZ. Use of the flatheads will ensure proper linup. As to the possibility of the head being unsquare in the recess? Not likely if Justin has done his measuring correctly and the mount holes are on the exact same pattern as the 3rd Gen steering box.
Long story short, Justin has used the proper fastener here, in the correct manner, in my honest opinion. If he should make a production run of them, and you buy one, by all means remove enough cast material to counterbore for a thin head 9/16 bolt to replace the flat head. In a years time when it breaks out, or the head brakes off, don't point a finger at Justin, the other three will be pointing at the one to blame.