Sorry Bud but you better go read a book on chambering real quick unless you really like the sound of broken reamers. Wear you safety glasses and stand way way back. This really ain't the way to go!-Rob
Posts: 6314 | Location: Las Vegas,NV | Registered: 10 January 2001
quote:Originally posted by Robgunbuilder: Sorry Bud but you better go read a book on chambering real quick unless you really like the sound of broken reamers. Wear you safety glasses and stand way way back. This really ain't the way to go!-Rob
Why? You've tried it and broke a reamer?
Wally
Posts: 472 | Location: Oregon | Registered: 08 March 2002
I will second Rob's reply, you need absolute rigidity and perfection in alignment for proper chambering. If you do not ruin a reamer the chamber will likely be over size and non-concentric if you use the compound, and it likely will not be straight with the barrel bore. Make up a test bar about a foot long, and use it in conjunction with a dial indicator to get that tailstock recentered. Once you get the hang of it, recentering the tailstock can be done in less than 5 minutes. I have the luxury of three lathes in the shop, one is set up and precision aligned for chambering, one is used for any barrel turning where tailstock offsetting is required, and the third is used for the other general purpose work like truing bolts and actions, making pillars, screws,etc.
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Posts: 8351 | Location: Jennings Louisiana, Arkansas by way of Alabama by way of South Carloina by way of County Antrim Irland by way of Lanarkshire Scotland. | Registered: 02 November 2001
Wallyw- Not trying to insult you, but if you do what you have described, you WILL probably break your Reamer and possibly injure yourself. Frankly, I've never even thought about chambering the way you described. Center your tailstock as John has described, zero your center-rest set your lathe at a speed of between 70 &300 RPM (depending on your Reamer) and Ream by using cuts of NMT .050 from the tailstock with your reamer held in a tap-holder( BY Hand unless you have a floating Reamer holder), such that it can spin without breaking your fingers off if it catches. Use lots of good Quality cutting oil and CLEAN your reamer Thoroughly and the chamber after each .050 pass. I use Acetone and compressed air. It takes a long long time this way,but you will produce a Concentric Chamber free of gouges, wrinkles and blood. Good Luck-Rob.
Posts: 6314 | Location: Las Vegas,NV | Registered: 10 January 2001
Wallyw I wasn't either. Quality Chambering requires the utmost attention to details & NO SHORTCUTS! It takes time so don't try to rush the job. Take the phone off the hook, lock the door, what ever it takes to bring yourself to to your highest level of concetration. Proceed slowly, follow these fellas advice & you'll do fine. You wouldn't want a surgeon to take shortcuts & do a rush job on you during surgury would you.
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Posts: 8351 | Location: Jennings Louisiana, Arkansas by way of Alabama by way of South Carloina by way of County Antrim Irland by way of Lanarkshire Scotland. | Registered: 02 November 2001
DeeBee- Books give you an idea of what it takes, but there is no substitute for experience. I was lucky enough to have an excellent older gunsmith as a guide who first let me watch how he did it, then trained me to do it myself. I'd strongly consider paying a pro to let you watch a few times. If you have basic Machine tool knowledge and common sense you can learn an enormous amount in a very short time. Alot of proper chambering is learned by FEEL and as BEARCLAW says requires dedication and experience. I don't know what you mean by chambering on a smaller lathe between centers. The lathe has to be big enough to hold the barrel, a center-rest and the reamer between a solid or rotating 60 degree center. The other option often used on smaller Lathes (but with a big enough spindle bore)is to support the barrel in the headstock between a 4 Jaw chuck and a Spider on the back of the spindle. This method REQUIRES PRECISION CENTERING WITH TWO OR MORE DIAL INDICATORS and RANGE RODS. You then again chamber with the tailstock never the compound. John Ricks and BEARCLAW are EXPERTS and the rest of us can learn alot from them. Hope this helps.-Rob
Posts: 6314 | Location: Las Vegas,NV | Registered: 10 January 2001
I'm reluctant to post, I don't want it to look like were ganging up on you.
However I would not recomend using the carriage or compound rest either. Even if you could attain perfect alignment you still would be lacking on rigidity which is paramount on chambering.
There is another way to avoid setting your tailstock over.............you can get a small boring head (designed for a mill) with a morse taper to compliment your tailstock taper, then machine an adaptor to use a live center instead of the boring tool. Then just dial your set over with your boring tool holder.
Posts: 1551 | Location: North Texas | Registered: 11 February 2001
WalleyW I assume that the reason you would want to do this would be so that you could easily center the reamer using the crosslide or the compound. The only flaw in the idea that I can see is ensuring that your MT tool holder is sitting at the same height as the axis of the machine. If the height is right I see no problem with the system of feeding with the carriage though I doubt that I would have guts enough to power feed! Feeding with the compound would also be an option. I don't really see any advantage to this though. Set up would likely be no faster than realigning your tailstock. Ultimately though any system that allows you to achieve precise alignment with the bore can give good results. An option you may want to consider is to make yourself an adjustable center to mount on your tailstock barrel. This way you can do your offsetting with the attachment and leave the tailstock centered. These attachments were sold by the Atlas co. but I don't know if such is still available. Fairly easy to make though. I have used a system of holding the reamer in the headstock and holding the barrel in a milling attachment. This was for an over/under barrel that I couldn't chamber conventionally. Not an original idea by the way. Worked OK but a little awkward. Regards, Bill.
Chambering with the compound rest sort of makes a reamer obsolete. IF you know what you are doing. I know of at least one "smith" that can chamber with a boring tool...given the proper dimensions to start with. But it's not something you could do on a production type basis, but for a one off type of job, when cost per hour is not a real issue, it CAN be done.
Posts: 211 | Location: Little Rock, AR. USA | Registered: 23 May 2002
Wally, my lathe has a taper attachment so I don't have the difficulty you do. But a pair of center buttons from Brownells makes it very easy to perfectly align your centers. If I didn't have a taper attachment I'd give a long look to Craftsman's suggestion of the boring head. Talk about a cheap taper attachment. I may try that with my boring head anyway just to see how it works. George
quote:Originally posted by George Stringer: Wally, my lathe has a taper attachment so I don't have the difficulty you do. But a pair of center buttons from Brownells makes it very easy to perfectly align your centers. George
Thanks George,
I used Brownell's Center Buttons for years. A year ago I bought a VHS tape on Tailstock Alignment.
Until viewing that tape I was always satisfied that miking those buttons fore and aft, top to bottom would insure I was set up to cut an accurate chamber.
Not so sure now. Anyone have thoughts on using Brownell's buttons?
Wally
Posts: 472 | Location: Oregon | Registered: 08 March 2002
I have never used the buttons but the system seems quite valid to me. I don't know what the tape you saw showed but I assume it dealt with the method of mounting a dial on the spindle then dialing around a dead center. then moving the quill out and relocating the tailstock to check for angular misalignment etc etc. Anyway I would think that the buttons would be an effective device as long as you were sure to check them in both directions and if you extended the quill and checked again. The problems that arise with tailstock alignment and wear are one of the reasons I really prefer to chamber in the steady rest. Many disagree with this and are of course welcome to do so. Regards, Bill
Still use the old method of a bar about 15 inches long between centers. Turn two bosses,one at each end and mike them. If there is any difference you can set a dial indicator against the live center in the tail stock and move the tail stock exactly half of the difference and all is centered. Take another test cut before going ahead with the chambering.
Posts: 239 | Location: North Smithfield, RI USA | Registered: 09 March 2002
On a related subject: Gunsmithing Tips book from Wolfe Publishing (Prescott, AZ) has an article on chamber boring. Using a boring bar to cut a chamber. Then use a throating reamer for the rest of the chamber (unless you have a boring bar that will reach that far into the bore). It all depends on what chamber your boring. It would be easier doing a 6PPC vs a 300H&H. I will have to try it on my CNC toolroom lathe at work. Of course proper centering and ALIGNMENT of the barrel is the first consideration. Then program the lathe to bore the chamber dims. Verify the dims with dial bore gages (.0001"). I'm sure glad I don't use that crude manual lathe anymore.
Bob G. The method you describe is the best method to set up to turn a true shaft but may not be the best if you are going to chamber in the headstock. The reason is that it won't show any variations in height between the tailstock and the headstock. Mounting a dial indicator on the carriage and checking the bottom of your test piece is valid only if the ways on which the carriage runs are absolutely true and level in relation to the headstock. The alignment of the head stock with the axis of the lathe is also important and again best done by turning a test piece and checking with a dial. By a little careful thought you can also check the tailstock for angular misalignment both vertically and horizontally at the same time. At some point you must accept what your lathe is capable of doing then work in ways to minimize the error and maximize the precision capabilities of the machine. Regards, Bill.
Frankly, since it only takes 15-20 minutes to chamber a barrel in a properly set-up Lathe using a thru-the barrel coolant system and a good Floating reamer holder, I don't see the advantage of programming a CNC Lathe to use boring bars and then have to throat the chamber. It might be fun to see what it would take to do this, but not on a routine basis. I read that same article a while ago and always wondered how good the chambers really were. I'd love to see some pictures. On a more interesting note, I have run into some very experienced gunsmiths who are using a geometric die head to cut the threads on their rifles using a turret lathe. I note that geometric die heads are often available on the used tool market pretty cheap ( dies are something else again) and I have heard of a guy who claims that he has done it successfully on a standard Lathe by adapting the compound. Someday,I'm going to buy a Turret Lathe and see how this works. -Rob
Posts: 6314 | Location: Las Vegas,NV | Registered: 10 January 2001
Bill I was going to mention about the trueness of the lathe bed in relation to the tail stock center height but failed to do so. I use a Clymer Floating Reamer Holder to eliminate any errors when chambering. I always use a steady rest. Have to be sure to turn a step true to the bore for the steady rest. Some people fail to realize that if you use a 3 Jaw or 4 Jaw chuck to hold the blank up near the chamber that the pressure from the jaws can and probably will cause an out of round chamber to be cut. I hope this helps out some Budding Gunsmiths.
Posts: 239 | Location: North Smithfield, RI USA | Registered: 09 March 2002
