Model Hex Head screws

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cfellows

cfellows

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One of the things I would like to do on my Fairbanks model engine is use Hex Head screws to improve the authenticity. I'm probably not the first to think of this, but it ocurred to me that I could just mill the round heads of socket head cap screws into a hex shape and have what I need without a lot of work. This is what I wound up with starting with a 4-40 screw...

IMG_2533.JPG


IMG_2534.JPG


I used an end mill to cut the facets, but a file and file rest or a grinder would probably give a better looking finish.

Chuck
 
I like the idea. Anybody got any ideas on how to plug the hex hole?
cheepo45
 
cheepo45 said:
I like the idea. Anybody got any ideas on how to plug the hex hole?
cheepo45
Click to expand...

You could fill it with solder, or even turn it down to the bottom of the hole if the the head does't get to thin.

Kel

P.S. I like the idea Chuck, sure beats making one out of small hex stock.
 
Chuck- I make them all the time from 303 stainless steel hex stock. A 5C collet chuck and hex collets makes it much easier. I simply turn down the shank to the correct thread OD and thread them with a threading die. 303 stainless machines really nice and a six foot piece of say 5/16 from MSC will set you back about 32 bucks and change. It makes a LOT of bolts. If you use the tail stock to push against the die holder, it keeps the threads nice and straight. I set the chuck for 40 rpm, and grab the handle with one hand, and apply tail stock pressure (just pushing it in the ways) with the other. As for threading fluid, I use Anchorlube or tap magic. It takes me about 10 mins to make a 10-32 x 3/4 long bolt with a 5/16 head. Anything smaller than a 1/4 inch gets threaded using the die and holder. I made a form tool for cutting the curved surface on the head. One of those hard de-blurring wheels really shines them up nice. Over the years, I have made hundreds of the silly things. Be warned, once you travel down this path, it is difficult to use anything else.....
 
I order my model scale bolts and nuts from American Model Engineering. Life is too short for me to try to make them myself.
 
Chuck
I did a similar thing and put them in the vibratory tumbler. I was worried about the threads so I put shrink tubing on them. About an hour with green pyramids and the looked great. Tool marks gone. The sharing tubing threaded right off. I've also drilled and tapped some aluminum scrap (thicker than the thread depth and again to protect the threads) and glass bead blasted the heads. After those screw making marathons, I've moved into Kvom's camp. Buy them.
 
Chuck,

I wonder if your Arduino controlled rotary table could be reprogrammed to thread these with a die? Just turn it the required number of revolutions (with a delay between steps to slow it down if necessary) and back it out at full speed.

If your stepper had the grunt, I would envisage there would be two procedures - Thread() and UnThread() that were called one after the other when a button was pressed and you would set the number of revolutions required as you do for divisions now. If you could do this, you could then add a menu to select between dividing and threading on startup so you never had to reprogram it.

If you were really clever, you would get it to swap from threading to dividing and have it stop after threading at the right location to mill your flats.

You've got the technology!
 
Thanks, all, for the comments and suggestions. Rod, my dividing head doesn't have enough power to turn make threads.

I'm going to try using my tool and cutter grinder to grind the hex heads. I think that will give me a better finish. Also, I probably won't fill the sockets since I would like to continue to use allen wrenches with them.

I would buy the hex bolts, but they don't have the sizes I need. For the head bolts, I need 4-40, 1.25" long. I would also need a hex head of 5/32 across the flats. The smallest that I've found available are 3/16".

If I made them out of hex stock, again, can't find any 5/32" hex available. I can get 1/8" or 3/16" in 12L14 and nothing smaller than 3/16" in 303 stainless.

I was really just looking for a quick and easy way to make the SHCS's less obvious.

Chuck
 
If you are bound to a manual lathe, there is still a quite fast way to make them:
Buy hex stock.
Grind a rose bit. A rose bit looks like a face mill with a bore in the center. With that, you can "turn" the right diameter (supposed the bore is of the right diameter) in one cut, without the work bending away.
Thread with a die and part off. With a turret tailstock or some DIY quick-change toolholder in the tailstock, it won't take too long to make one or ten. Hundred will get quite boring.


Nick
 
Where can you buy hex steel stock for 10 , 12 and 14BA ?
 
For 10 and 12 BA its likely you would have to buy nearest metric which would be 3.0mm and 2.5mm which are a few thou oversize.

J
 
One of the things I would like to do on my Fairbanks model engine is use Hex Head screws to improve the authenticity. I'm probably not the first to think of this, but it ocurred to me that I could just mill the round heads of socket head cap screws into a hex shape and have what I need without a lot of work.
Click to expand...

I must be missing something here. We have large machines which do this at high speed, in most any size you could want. Why bother making your own nuts and bolts?

Puzzled.
Cheers
 
I am not in the screw making business (except when I screw up) but the rose bit is a great idea for turning to size skinny parts.
If the hole needed is too deep, is easy to make a tubular carrier for a drilled through rose bit. The carrier may be reused.
 
It is a bit unfair, and I haven't tried it yet. But I would shape them in the CNC-lathe with spindle orientation.
The shaping works, I have tried that (with the background of making small hex head bolts in any size).

Nick
 
Don't expect them to be true BA size heads, if you are lucky they will be 3mm, I have known even 12BA's to turn up with 3mm heads. As a consequence I now machine all my own bolts.

You also need to consider what size you "BA" spanners are. If you have old spanners the 10BA will be too small to fit modern 10BA heads, but if you have metric "equivelents" you will be ok. For 12BA spanners it is worth looking out an allen key headed screw as 2.4mm A/F is a standard size.

Jo
 
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