Hi all. Any one have any information on the fixturing necessary for threading a Hepburn receiver in a lathe, for a barrel?
Printable View
Hi all. Any one have any information on the fixturing necessary for threading a Hepburn receiver in a lathe, for a barrel?
.
The Upper Missouri Trading Co. in Nebraska makes both raw & machined Hepburn receivers, and might be able to help you out (tel: 402-388-4844)
http://www.uppermotradingco.com/
.
thanks Pietro, called them this morning, waiting for an answer.
I'm not a gunsmith, but I am a graduate of the USAF machinist's course and have been a lifelong hobbyist. My lathe is an English Myford, very well equipped, but also pretty small.
Rather than try to swing that Hepburn receiver on a fixtured faceplate, I would put the action on a milling attachment on the cross slide. Cutting would be with a single point tool in a boring head in the headstock and finished with a tap, if you can get one. I have not done this, but this sort of setup is what the steam engine guys do for cylinder boring.
Thank You Nueces, I had not though of that. Did think about the boring head approach but on the mill not the Lathe.
Yessir, the lathe offers power feed and screw pitch feed.
So I think you are wanting to cut new threads into the Hepburn...Quote:
Originally Posted by Steelpounder
or fit a barrel to an existing Hepburn? which I thought at first but based on your response to now - not.
Hepburn's have square threads. If you have a repo raw action, you can cut what every you want in it, but .... that does not address your question.
It is something of an arduous setup to lathe cut them but with a big lathe (well stuck down to the floor) and a 90 degree angle plate and about an afternoon setup (for me) you will get a great job. I also have taps and dies for some of the older "v" threads for clean up of finishing BUT I know nothing of a tap for square Remington threads.
Brownells has the correct square threading tool cutter if you do not want to grind your own.
Thank you Chill,
Yes I am wanting to cut the barrel threads into a reproduction receiver. So if I am understanding you, you bolt an angle plate to a face plate and then clamp the receiver to the angle plate and center it up?
I know there are acme thread taps available and believe there are square taps but these are normally a longer tap with a straight portion at the front and finish at the rear While the hole is thru the back of the receiver would limit how far the starting portion can go thru and you may not get to the finish portion. It could be done on a cnc mill but set up will still be a pain on an angle plate with strap clamps. Getting it square and true is going to take some patience tapping it around. Maybe backwards in a 4 jaw but this will require a pretty long boring bar to reach past the tang and thru the receiver.
Yes. Nothing to it. :roll: :mrgreen:Quote:
Originally Posted by Steelpounder
I shoot with a few Honest to Goodness real gunsmiths that work metal everyday can make a great job of this. For a shade tree guy like me, it would take a long time dialing it in and then I would be sweating cast bullets cutting it. Still, life is short and the way I see it. I have to try. That is the only way to learn. right now I am working up the courage to do this with a Win Highwall cast action. Just want to get it right the first time.
I see by your handle - for what it is worth... there is a fellow BPCR rifleman I shoot with in Southeastern Wyoming who makes knifes full time by the name of Jim Rodebaugh. I have seen his shop. Wow - big fun!
The angle plate method can be fine if it uses the size of fixtures suited to a really large lathe. For a smaller one (and mine is a Myford too) I would rather clamp a flat-sided receiver down on the cross-slide, with a spacing block and shims to get the right height. With a micrometer boring head, which needn't be a big size and will be useful for other jobs, you can take cuts as fine as you like.Quote:
Originally Posted by Steelpounder
A large Acme tap is likely to be very expensive, and a square tap, if you can find it, very very expensive. But they shouldn't be necessary. I've never understood the argument that the square thread is peculiarly difficult to cut on the lathe. A cylindrical surface (root or crest, either will do) is easier to cut to true diameter than an angled one. The lathe tool, to have the most metal backing up the edge, needs to be slanted to match the angle of the groove you are cutting. So a ready-made one for a different diameter or pitch may need to be modified.
I would tailor the barrel to match what you have achieved in the receiver, rather than the other way about. If things go wrong, you can't cut an inch off a receiver and start again.
Doc in Upper Missouri 402-388-4844 is now semi retired but is usually in on Wed thru Saturday and can help as he has all the fixtures for finishing his Hepburn castings.
thanks Chill,
I know Jim pretty well he is a great guy. We get together a few times a year at knife shows etc.
I want to try this myself just because I think I can. if I mess it up it will suck but I wont be out too much as I got all this stuff really pretty cheap and hopefully I will learn at least what not to do.
Ballistics,
I have a 13x40 import lathe with a DRO setup. do you think this is large enough. I am thinking that the boring head in the chuck and the receiver on the cross slide sounds like the way to do this for me. this way I can face the receiver then dial in and bore the miner diameter then cut the threads with out changing the setup helping to insure alignment.
Sounds like you have a plan. Pictures during the process would be great if you can, for us in the peanut gallery.Quote:
Originally Posted by Steelpounder
I bored and threaded a Ballard receiver casting (for barrel and tang) using the faceplate and angle plate method. The casting had pilot holes cast into it, so I turned pieces of scrap round stock on centers to as good a fit as I could get in the rough-cast holes.
I put the stub in the receiver, loosely clamped the receiver to the angle plate, put the center hole on the tail stock center, and by dint of tapping, tightening, adjusting the angle plate and the receiver, indicating the stub along its length, loosening, tapping and repeating, got the stub running true. Removing it allowed the facing, boring and threading of the receiver hole, with the hole as centered and accurate as the casting would allow. The tang hole was done the same way.
As I recall, it took a couple evenings in the Shop Class to finally get it trued in. I've seen real machinists tap, tighten, indicate and get these things "zero-zero" in a couple minutes, but the beginner, if he is careful and patient, can "get there just the same," like the song says.
Unless you have an original barrel you absolutely have to use, I would advise against anything except standard V threads. If this is your first receiver casting, you have enough to occupy your mind already. Set a carriage stop so your single point tool is as deep inside the receiver as you want the threads to go, and use the trick of running it upside down on the far side with the motor reversed and the carriage feed going out.
I didn't bother bolting junk on the faceplate to balance it. Everything was done as slowly as I could run it. I sweated bullets anyway, even though the classroom was nicely air-conditioned.
Thanks Bent. Standard threads are something to consider had not really thought of that.Quote:
Originally Posted by Bent Ramrod
Quote:
Originally Posted by Chill Wills
Yes, that was what I was trying to say but didn't well. With a raw casting, a you can see how much meat you have to work with and put a more conventional sixty degree vee thread in it. And then too, you have only a vee thread to cut when you barrel it. And really, who cares if it is not a square thread.
Bent Ramrod - that is a good post. My lathe is an old Southbend 9 and somewhat small for these kinds of projects. The one casting I have done, I really did not do alone. It was a group effort. I took it to a friends who has a much larger lathe and it went a lot like you described. We did not try to counter balance it either. Just turned it slow.
Cutting on the back side takes me twice to think about each move but it does works and it great for starting the thread - and no crashes.
I would love to have a cast 8620 Ballard action to build up. How did yours turn out? Sorry-OT
I hope Steelpounder doesn't mind this. But being this is a query on machining a cast receiver for a Hepburn, and since nobody has come forward with a Hepburn casting set, maybe this example can at least provide some general information, anyway.
It took about three months of three evenings a week to do all the "big" machining jobs on the casting set, and I've probably put two months' worth of similar time on the handwork for finishing. Other things compete for my time, so I have a ways to go yet. The breechblock and extractor work with the lever in the receiver, but are still a little tight. I'm still spotting and filing, as you see.
Attachment 203173
Here's a blurry photo of the facing and threading on the receiver. Sorry it's out of focus; my camera skills are right in there with my machining skills. By the way, the pilot hole for the forend locator was out of line. Not my fault, but I didn't want to do a lot of extra work to correct it. I enlarged it some, so it's a little closer to the centerline, anyway. It'll be covered with wood when the rifle is done.
Attachment 203174
With the receiver threaded, I made a threaded rod to fit, with a block bolted along it, so I could mount the receiver in a dividing head, with a tailstock center, on the milling machine. Then I could do all my subsequent measuring and cutting off the barrel centerline and get the sides to an even thickness. I also used it to do the octagoning on the receiver top, the rebate along the sides, and the cool faceting on the octagon points (like the example in the picture) by turning and tilting the dividing head. A dividing head is a pretty useful little thing all right. Don't know how many pages of scratch paper I filled with calculations, but they were considerable.
Attachment 203175
Finally, here's the "sophisticated" fixturing and tooling I made to do all this. Looks like junk (hey, it is junk) but it did the job. The threaded piece screws into the barrel threads and the aluminum block bolts into the breechblock slot so nothing can unscrew under the cutting side pressure. That aluminum collet was for holding the tang casting in the lathe chuck for threading on both ends. Talk about hard to grab onto; that thing took longer to fixture than it did to thread.
Attachment 203176
Chill Wills, yes; the lathe was a big one; must have had a 20" swing anyway. I would guess at least 14" would be needed for one of these jobs to get the barrel hole in the center. All the dimples in the castings for locating crosspins and screws were close enough. I made them out of drill rod, in standard sizes, with standard threads that can be done with taps and dies. There was plenty enough work to do without being "authentic." I have to thank Gene, our instructor, a master machinist and amateur gunsmith himself, who was fully in sympathy with my aspirations, and always interested and there to help. That night class was the only one to my knowledge that the instructor had to throw the students out at 10 PM so he could go home and get some sleep.
When Bison Manufacturing (later Tools International) offered these casting sets, I figured this was the only way I'd ever be able to afford a four-finger loop, pistol-grip Ballard, the prettiest rifle ever made. After threading and turning, I set a .40 caliber Shilen barrel blank up in the dividing head and made Rigby Flats on it, just to be different. They still need some hand work before they are finished. Chambering, heat treating, bluing and stocking are yet to be done. I sure hope I can shoot it by the time I'm 80. :mrgreen: Even so, the work itself is very interesting. You really get a sense of what a genius somebody is who can set up a factory for the mass production of these things. Or anything at all.
Rodney Storie posts on the ASSRA Website occasionally and has mentioned that he's going to retire soon and may have time to revive the casting set business. One hopes. Steelpounder, please keep us apprised of your progress on your Hepburn project.
don't mind the switch at all. seeing one receiver threaded is pretty much the same as seeing another. at least in principle isn't it?
I take it that 13in. is diameter of swing over the bed? My Myford is more usually termed a 3½x31, aka 7in. (long bed and previously owned by one careful bassoon repairer.) I'd do it on that, taking progressive light cuts, so yours should be ample. You might get a little more rigidity, and thus smoothness of cut by holding the boring head in a headstock collet rather than the chuck, although being an eccentric tool you don't need the extreme concentricity collets are usually used for.Quote:
Originally Posted by Steelpounder
If you do use a tap, it can be aligned by the centre hole in its rear end, in a 60 degree headstock centre, and turned with a wrench. But the amount of force necessary to turn a large tap is brutal treatment of the cross-slide. With a some actions I would have a steel bar and brass shims to hold it against the turning force of the tap. With a long, thin-sided receiver like the Martini I would make sure it is clamped at both ends, and instead of that bar, a handle integral with one of the spacer blocks which raise it to the right height.
thanks Ballistics.