I am in the midst of fixing some farm machinery with new sheetmetal. The metal I am using is 14 gauge, and the proximity to moving parts requires carriage head bolts. The previous metal used 1/4" carriage head bolts, and I would like to do the same. I don't have any idea how to create the square holes. Each piece of metal is roughly 3 feet by 2 feet, and the holes will be within 2 inches of one side of the metal.
Any help would be appreciated.
I guess it could be done with a broach and a press, if all the holes are within 2" of the edge. If you have access to both sides when it's installed it might be easier to use some type of round head bolt with a recessed Torx or allen head so that it can be held while tightening.
Jim,
If it's equipment that needs to be in the field tomorrow, and will spend the rest of its days in the barn, then a slightly oversized hole will become squared when you cinch the bolt tight. Of course, you may have considered and rejected this method, also.
If it's a restoration project, or has to be "just so" you could try a Greenlee chassis punch, a nibbler (Google it) or a square file and a cool refreshing beverage.
If clearance is really tight, you might look at garage door bolts, which are like carriage bolts without the dome on the head. Home centers have 'em in the garage door section, not nuts and bolts.
Good luck! "Chip" in Columbus
How many, to what tolerance? What's the budget like?
1) Prick punch, center punch, pilot drill then 17/64 drill. Create corners with 3 corner file. 2) CNC Plasma torch3) Water jet
4) Laser5) Plunge EDM
6) Machine and harden a 0.27" square punch and matching die shoe. Load into your arbor press and pop them out. Use lubricant and wear eye protection.7) Drill and square broach
--Winston
These would have been punched originally. It is certainly possible to get one of those Whitney hand punches about the size of bolt cutters, and order a 1/4" square punch and die set from Cleveland Steel Tool or the like.
I'd punch the holes anyway (drilling sheet is a real bummer) even if you only have a round punch, punch 'em a little big and just pull the bolts through.
GWE
How about a bolt like a lugbolt on a car? A short splined section up near the flat head that is pressed into a round hole.
Drill a 1/4" hole, heat the area around the hole to red with a torch, drive a carriage bolt or a tapered square punch into the hole. You could probably do it cold with the punch, but I think you'll get less distortion with the heat, if that's important to you.
Ned Simmons
For a few holes in 14 ga. material just drill the holes & pull the bolts in with a wrench. The hole will be stronger when cold formed by the bolt square. Be prepared to break a couple of 1/4" bolts. No big deal! Cheapest & quickest way out. I've done this on repaired lawnmower decks. Bugs
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