Jerry Sharrett, Indicator question

K

Kirk Ethridge

Guest
Jerry,

I ordered one of the indicators (interapd) with the 2.5 inch long stylus today,(that you have promoted, bragged on on numerous posts in the past for indicating a barrel for chambering/fitting to action)

I beleive i understood the instrument comes with a carbide contact point. is this ok.? I think when you indicate in , this point on the barrel will be cut away with the reamer anyway, i was just wondering if i sholud get one of the teflon or nylon contacts for the instrument? ie is the hard carbide contact point prone to score the barrel during indication.... i think the pressure would really be to low to do this, but figured i would ask any way..... also, are you guys zeroing off the lands or groove? (i know this is debateable ,,,just wanted to know what you did)

if you don't mind, e mail me how you are indicating in, I read 2 point indication. (mine will have to be off of steady as both my lathes are much to large to chamber at the headstock). ie what 2 points are important on the chamber end. my muzzle end is on center with Greg tannels high pressure muzzle flush system). and i would have to have a barrel about 40 inches long if i wanted to use a spider to indicate the muzzel this way, it really is dead on anyways since it is on center anyway on the muzzle.

thanks!

Kirk

kirktink@earthlink.net
 
If you are chambering through a steady how do you plan on indicating in the barrel at the point where the throat is located? Not saying it can’t be done but this is why people are chambering through the headstock with an independent 4 jaw or spider at the chamber end of the barrel. When chambering with a steady you typically cut the tenon end of the barrel to length, cut a new center with a piloted center reamer, run a center in the tailstock into the new cut center on the barrel and re-cut the OD of the barrel. Now your barrel in the steady is running true to the bore but at the very end of the chamber and the throat may or may not be centered with no easy way to offset it in the steady. You could use a bell chuck running in the steady and indicate the barrel in with it and solve the problem but that is possibly more work than chambering through the headstock. You could search for solutions that have been posted for long headstock lathes and chamber through the headstock. Jackie Schmidt, Jim Borden, Joel Pendergraft and others have posted many solutions to this.
 
indicating throat

indicating on a steady is probably easier than on 3 or 4 jaw chuck... that is no problem at all. (at least on my 14/40 and 15/50 2-3000lb lathes) I've not worked with the small lathes. maybe they don't utilize the same type steady rest?

My bet is more of the high volume rifle smiths chamber this way (off steady) than through the head stock of the light weight lathes.

My main question involved the contact point on the indicator i ordered, that Jerry has mentioned many times. I was just interested in how Jerry did it with his small lathe. (for reference)

I know Jackie and Jim chamber off steady, unless they've changed something since i've talked with them about chambering. I don't know Mr. pendergraft.

the steady rest is adjustable from each contact point. and is very simple to indicate in dead nuts for the throat. I have one friend that made a 4 point contact steady rest, but i don't think it's any better than a 3 point one. one cannot get a barrel indicated in any better than between centers. and chambering off steady,,, I'd say a good tool and die maker, and a bunch of top rifle smiths would tell you this method is the most accurate method of the 2. (there is no doubt plenty of good barrels are fitted on the little lathes a lot of the home work shop guys own besides, one has to use the equipment he owns or has access to.)

Kirk
 
Kirk

Jackie chambers through the head stock on a big lathe, a Pratt and Whitney if I remember correctly. He come up with a device to hold the end of the barrel captive in the spindle. I believe Jim Borden chambers through the headstock too. I don't know what he does on the outboard end, though.

I have chambered both ways, and prefer through the headstock. It's a single set-up operation, and there are less variables (tailstock, steadyrest) to contend with. I have a big lathe, so I use a sliding center to hold the barrel in the spindle. Works like a charm.

My opinion? Either way, done properly, will produce rifles that will shoot.

Justin
 
All I'm saying is if you have an ID (throat) that is not concentric with the OD (barrel shank) and you are running it in a steady at that particular point you can move the steady around wherever you want and it won't change the fact that the ID is not running true to the OD that is spinning in the steady.

Steady's big or small, they work about the same.

I am not arguing the fact that good and succesful work is done by both methods and lots of smiths chamber in the steady.

Jackie has written many times about his headstock chambering method he uses, Jim Borden has posted pictures of his tooling for chambering in the headstock with a long headstock lathe as has Joel Pendergraft. Jackie's is really simple, Jim's a little less so and Joel's is more complicated but very nice. I was just trying to point you to long headstock solutions and was not trying to change your methods.

I have the same Interapid indicator and it has not caused any damage to the bore. I have Mitutoyo's and Bestest (Brown & Sharp) as well and they don't do any damage either as far as I can tell.
 
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Mr. Snyder, you are correct. If the OD of the barrel is not concentric to the bore, you will never be able to indicate the bore properly. I have both the Interapid and Mitutoyo like Jackie uses. I prefer the Mitutoyo as it has a short probe and you can put the whole barrel of the indicator in the bore and not worry about the flex in the probe.
Butch
 
I don't think you could ever expect the OD of the barrel to be perfectly concentric with the bore. The odds of that are quite low.
 
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