Hinges

[Vinny]

A buddy of mine is rebuilding an old Model T Truck.  Then a Model T car is next.  The windshield is attached with two hinges and when he got these two projects he was only able to find 2 halves of a hinge.  Both in bad shape.  The only place that sells replacements wants $100 for them.  So I told him we'll just make them.  Looks easy enuf as you can see in the pics below.  

Before I get started, tho, I have a few questions.  I figure I'll just use angle stock.  My choices seem to be hot rolled or aluminum.  There's only a couple bucks difference in price at Speedy so is there any reason I shouldn't use aluminum for these?

As you can see in the pics, there are 12 indents for balls to go in.  The originals were done on a press.  I'll be doing these on a mill.  The holes the balls go into are 0.200" at 0.050" deep.  0.200" is about a #7 drill, or should I use a ball end mill instead?  If I do the mill I'll probably go for 1/4" since it'll be cheaper and I can source it locally.  Would I use a 1/4" ball or is there some formula that's supposed to tell me what size?  Never worked with individual ball bearings before (can ya tell?).

Without further ado, here are the pix.





and my scraggly drawing.  Couldn't find the clipboard.


if you want a larger drawing, do a View Image on the drawing and change the location to be hinge4.jpg.

Thanks for reading!!

[PixMan]

Nice project! I'd LOVE to make something like that.

How are you going to make the "male" part of the ball detent indexing? I might attempt doing it the hard way with a concave "corner rounding" type of cutter. Of course it would be easier to spot the locations on the back side and make a punch and die to press them in.

OTOH, does the mechanism actually use the male side or just the female side where it's so easy to just make the pattern with an appropriate ball end mill. Nothing would appear on the other side that way though, of course.

I wouldn't use aluminum, too weak for the forces it will see. I'd use 316SS or (at least) 304SS, or a regular steel and chrome plate it.

You should be able to get a close enough measurement of the ball sockets with a simple radius gauge, no?

[f350ca]

Neat project. I'd also go steel for strength, durability and authenticity. Rather than angle I'd be tempted to cut them out of a suitable piece of square tubing to get the rounded corner, or have a piece of plate bent. The dimples on the back would be hard to duplicate.

[PixMan]

If you have a hydraulic press you could make a fixture to press the ball shapes...with a ball. Make a female pattern by dimpling a bottom die plate with a ball end mill. To determine what size ball mill you'd use, first figure out what the ball socket radius is on the top side, add the material thickness and get a ball mill of about the equivalent radius of 1/2 the diameter of the mating ball plus material thickness. Spot the top side pattern, press the ball into the die you made.

[Vinny]

The male side does nothing. The two female sides hold the balls. (that almost sounds dirty) There's a bolt that goes thru the center. I have a piece of 1/8" steel angle which is about the thickness of the original, so I may just use that and index the 12 ball locations and press (I do have a press) the ball into place as Ken suggests.

I don't have a radius gage but as close as I can tell the ball socket dia is 0.200" and is 0.050" deep, which it seems I could use the 1/8" angle I have and rather than press I could just use a ball end mill. The original balls are long gone so I figure 1/4" might be a less expensive route although maybe the originals were 1/4" since they only go in 0.050".

He's not trying to do an original restore and isn't worried about the hinge not looking 100% like the original. So if the dimples aren't there it's no big deal. The originals are black but chrome would look nice. I wonder if I have any chrome shops around here.

[TomG]

Are you sure the originals use loose balls? All of the hinges like that I've seen use a male/female stamped disc, clamped together with a threaded shaft and knob. I would suspect that the missing halves have raised dimples to mate with the parts you have, not loose balls.

Tom

[Vinny]

The pics I've seen of the replacements have outside dimples on the outside of both halves. If I can find the link to it, I'll post it here.

[PixMan]

Sounds like you should simply get 5mm (.1968") and use those. It wouldn't be out of the norm for a Ford of that era to use them, as American industry hadn't yet perfected the manufacture of the balls for ball bearings and they were (and most still are) imported from Europe.

http://www.mcmaster.com/#standard-steel-balls/=wggb20

$7.89 plus shipping for 100 of them sounds cheap enough. You're going to drop and lose about as many as you actually use when you assemble.

Use one (or a couple) for pressing the shape. Making the "die" would require a ball mill of about 0.3218", so just get an 8mm one and call it good.

[Brian]

I think If I had to make that part and originality was not required. Steel angle would be my choice of material , the dimples put in with the end of a drill. and for the mating part simply drill and tap then screw in dome headed screws with Loctite. after painting no one will know .
But I always am simple minded. Brian.

[Vinny]

I was thinking about this a little while ago and Tom may be onto something. What if those dimples are actually detents? Now I really want to find that pic of the replacements.