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TRX
11-06-2012, 08:48 AM
I need to make what are basically some really long, skinny bolts. 6" long, .187" diameter, .250" head at one end, 10-24x5/8" threads at the other. Material will be O-1 or 4140. Diameter of the .187" shank is +/- .002".

I need about a dozen of them, though I might make more later. I can do it by the "ghetto" method of pulling a bit at a time out of the collet in the headstock, machining it in sections, and finishing off any steps with sandpaper, but what would be the "right" way to do these?

A) box tool. I've never used one. Once, when working in a production shop, I found one under the bench and was trying to set it up when the supervisor stopped me, "those things never work" and had me continue making long screws the same way I described above.

B) centerless grinding. I don't have one, I don't know any shop around here that has one. Probably couldn't afford one, and one cheap enough to buy would probably take more TLC than I can budget for it. I have other occasional projects that could sure use one, though.

C) center grinding. I don't have a toolpost grinder, but I have a 3-ton Storm-Vulcan crankshaft grinder that will hold .0005" repeatably. I could rough the rods on the lathe, then grind and let the rods "spark out" on the grinder for each position of the wheel.

D) start with .187" rod, make a clamp to hold one end while I heat it red hot and beat it into a lump with a hammer. Then machine the lump as needed.

E) start with .187" rod, weld lump onto end.

The head forms a slide stop and has a broached hex, so I'm not considering solutions that involve sleeving the .187" shaft up to .250".

Comments?

alanganes
11-06-2012, 08:56 AM
Here is one way designed for precisely what you are doing. While it requires you to make a tool, who doesn't want to do that!? Then if you need to make more, you are set up, and you have a neat gadget for other projects. Not my idea, this from the fertile mind of Frank Ford:

http://www.frets.com/HomeShopTech/Tooling/MiniFollower/minifollower.html

Loads of other cool stuff on his web site.

TRX
11-06-2012, 09:25 AM
I'd forgotten about Frank's cute little cutter rig! And I've admired the pictures several times...

Optics Curmudgeon
11-06-2012, 09:40 AM
Once, when working in a production shop, I found one under the bench and was trying to set it up when the supervisor stopped me, "those things never work" and had me continue making long screws the same way I described above.


Now you know how they got to be a supervisor, they weren't working out running the machines . A box tool is just a cutter and follower in one piece. Properly set up (not difficult) they do a fine job.

wierdscience
11-06-2012, 10:41 AM
For the heading operation make yourself an upsetting die.This one could be easily modified to include a recess for the size head you need-

https://www.youtube.com/watch?v=qDRjYu4BZLE

Toolguy
11-06-2012, 01:08 PM
Another informative video available from the same link is "Using the Blacksmith's third hand for riveting".:)

Paul Alciatore
11-06-2012, 01:23 PM
You could buy the rod, thread both ends and then silver solder a nut on one end.

bborr01
11-06-2012, 04:40 PM
Use 1/4" rod, thread one end and silver solder the head on. Easy and quick.

Brian

HWooldridge
11-06-2012, 05:00 PM
Here is one way designed for precisely what you are doing. While it requires you to make a tool, who doesn't want to do that!? Then if you need to make more, you are set up, and you have a neat gadget for other projects. Not my idea, this from the fertile mind of Frank Ford:

http://www.frets.com/HomeShopTech/Tooling/MiniFollower/minifollower.html

Loads of other cool stuff on his web site.

That's basically a Swiss screw machining solution - keep a guide bushing next to the cutting tool.

Mcgyver
11-06-2012, 05:37 PM
I would go with the silver solder solution.....just for interest you could google and find a swiss lathe operation and get a quote. Shipping costs would be negligible

krutch
11-06-2012, 06:12 PM
Hope I can explain this without pics or drawings.
A drill bushing held in barstock to keep small diameter rod from pushing away and the cutter just pass the bushing where the work exits the bushing. Works well for small runs. I haven't threaded this way yet because the cutter was not easily adjustable. Lathe bit clamped and adjusted by loosening clamp screws then turning set screw to move bit into work. No dial to verify cutter infeed and set-up too "thrown together" to easily use dial indicator. I don't even have the "quick set-up" to photo anymore.
Started a drawing to make tool for this and lost drawing with 'puter crash and haven't gotten back to it. Was going to make so cutter had its' own crossfeed and bushing exchangable for universal use.

Barrington
11-07-2012, 06:23 AM
Since sleeving is not an option because of broached head, how about silver soldering something like this ? :-

http://i564.photobucket.com/albums/ss82/MrBarrington/BoltHead.png
Or even use a Loctite if the temperature/stress conditions allow ?

Cheers


.

TRX
11-07-2012, 05:08 PM
It's the slide stop part that disinclines me from a two-piece solution.

bborr01
11-07-2012, 09:08 PM
TRX,

I missed the part in the OP about not considering a 2 piece solution. If you were going to need a lot of them I would recommend cold forming. You could start with a .187 shaft and cold form the hex, slot and most anything else. The price would likely be prohibitive for a small run though.

Brian

TRX
11-09-2012, 12:50 AM
Is there some design information anywhere that would tell me how much pressure would be needed to cold form a head on a .187" 4140 shaft?

Being a hobby project I don't mind making some dies to hold the part. Is this something that has to be struck, or would a big hydraulic press work?

Jaakko Fagerlund
11-09-2012, 04:00 AM
Is there some design information anywhere that would tell me how much pressure would be needed to cold form a head on a .187" 4140 shaft?

Being a hobby project I don't mind making some dies to hold the part. Is this something that has to be struck, or would a big hydraulic press work?
I would guestimate around 20 tons to form it, but this is just a WAG based on some things and interpolating from them. I would definately look at striking it with something, much more force in a smaller package than in a hydraulic press.

bborr01
11-10-2012, 10:08 AM
Is there some design information anywhere that would tell me how much pressure would be needed to cold form a head on a .187" 4140 shaft?

Being a hobby project I don't mind making some dies to hold the part. Is this something that has to be struck, or would a big hydraulic press work?

TRX,

I don't know how many tons it would take to cold form the head. I just worked on the dies for the cold formers and the engineers calculated the tonnage. We did sometimes use a hydraulic press to for prototype parts and it worked fine. It was an electric/hydraulic press so it kept the metal "flowing" once it started to form. Not sure if that would be an issue if using a hand pump press. Possible that with the right tooling that even a well placed blow from a sledge hammer might work. Just a thought. It also strengthens the head as it is being forged so to speak.

Brian

Duffy
11-10-2012, 10:21 AM
You know, I have come late to this thread, but it occurred to me that what he wants are standard electric motor frame bolts-the ones that clamp the feild core between the bell ends.
All of the solutions ARE ingenious, but slight modification to off-the -shelf bolts would be a LOT simpler.

TRX
11-11-2012, 07:50 AM
No, they need to be 4140 or O-1. I don't know what some generic motor bolts might be made from. They aren't really bolts, they're actually spring guides in a highly stressed application, which is why I described them as "basically" bolts. Your suggestion was pretty slick, though.

I have a 60-ton air-over-hydraulic jack and a small press frame that are practically begging for an experiment, though...