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Thread: Grizzly Vs Clibre specific indicator rods

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    JBCGUNS is offline Aluminum
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    Default Grizzly Vs Clibre specific indicator rods

    Just about to put in an order with PTG.
    Any opinions on which way to go in regards to setting up with either PTG calibre specific indicator rods (full range of cals.) or purchasing the 5 or 6 Grizzly Rods. I assume that you need to buy a pair of bushings for each Grizzly rod in each bore size you're working on? and if so are they the same bushings that fit the PTG removable pilot reamers?
    Cheers,
    JB

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    Swarfboy71 is offline Aluminum
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    How do you indicate the bores at the moment?

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    Sea Sick Steve is offline Aluminum
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    Given the two choices you have provided I would opt for the grizzly rods, I have not gotten repeatable results with the indicating rods. I have been using the indicating rods to get my setup close, then I use an indicator with a long stylus to read the bore directly

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    I sort of side with Steve. I don't know what a machinist or tool and die maker might say. But dialing in a shaft whether inside or outside especially over an uneven or broken surface, over two or three inches may be a little bit haphazard. Trigonometry is not exactly in your favor. Make sure you use a floating reamer holder and cut slow and light so the chamber does not outsize. The floating reamer holder will let it follow the bore even if you get it off a smidgin.
    union reek likes this.

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    Butch Lambert is offline Stainless
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    Steve and Speer, I agree with both of you.

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    300sniper's Avatar
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    if i have time tomorrow morning, i'll photo a little experiment about the error of the grizzly rods. i guarantee that there's error but it might not be quite as bad as some believe.

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    There are a couple ways of dialing in one end only. One is to use an 8 inch precision ground pin and insert it 4 inches into the barrel. It has to fit close but not so close that it smears the lands. Then use 2 dial indicators one where the pin leaves the barrel and the other at the end of the pin. Get both indicators to run zero when the lathe is spun by hand or low speed by adjusting the cats head on the inboard and outboard end of the spindle.

    The second uses a smaller diameter rod with a close fitting rolling pilot on the end that closely fits the bore and you run it in and out of the barrel to the depth of your chamber to be with a dial indicator on the rod near the beginning of the barrel. Use the cats heads to dial it to zero over the full length of the chamber.

    After its dialed in insert a precision ground rod into the muzzle and and measure the run out and mark the high side with a felt pen. Then strip it right down and repeat the whole thing a couple more times.

    Its been my experience that a barrel becomes visibly bent to the naked eye when it has over .004 deflection. According to McGowen all of their barrels run closer than .009 inch over 29 inches. Its hard to get much out of Dan Lija some times but in an email he said they culled out barrels with visibly crooked bores. He also said that .004 inch was easy to pick out of a pile with a visual inspection.

    If you see more than .005 run out when setting it up 3 times and especially if the high point changes at all in your three tests. Well you can draw your own conclusions. Obviously if you are using a floating reamer holder it makes no difference you could be out 1/64th of an inch and it will still probably work fine. The reamer is going to follow the bore the same as when you do it between centers. After all the reamer is piloted, it is tapered, it can float and the material is turning not the reamer so the common laws of mechanics force it to go straight down the barrel. The only fly in the ointment is that the hour or two spent setting it up and dialing it in is simply a pseudo effort. Like lipstick on a pitbull. Its all show.

    Also, the notion that dialing in just the chamber end will give a more accurate throat is a misconception if you use a floating reamer holder. The reamer will go straight down the bore just as if you you were doing the job between centers with the barrel floating. To alter direction of the reamer you have to FORCE the reamer to go where you want it to go by using a solid reamer holder like an ER or MT collet in the tailstock. You can fool the reamer by precutting the chamber with a boring bar and then using a floating reamer holder. A lot of BR guys do this if their machines are not close enough to use collets.

    ADD NOTE: NEVER attempt to cut a chamber with the barrel held solid and using a solid reamer holder like an ER or MT collet if your centers don't come together .001 inch or under. The reamer will become a single point cutter and it will cut an outsized chamber EVERY TIME.

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    Butch Lambert is offline Stainless
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    Speer, You understand the process and that is why I chamber differently than mentioned.

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    300sniper's Avatar
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    i didn't get a chance to video what i wanted to this morning. i did try to video the finished chamber runout but it was in and out of focus enough to make it worthless. the throat and chamber runout was in focus but you couldn't even tell the barrel was turning. the interapid 74.111965 sure didn't show it.

    at this point, i like dialing in the bore using a a grizzly rod (with a small plumb hanging for weight to eliminate any clearance issues between the bore/bushing and bushing/rod), fitted bushing and a tenth indicator reading on top of the rod and then double checking with the long reach interapid. i personally find it much easier to dial in on a round surface vs. multiple lands/grooves.

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    Quote Originally Posted by Butch Lambert View Post
    Speer, You understand the process and that is why I chamber differently than mentioned.
    Yeah I believe you explained it once. You dial in both ends so that you have a predetermined amount of deflection with the barrel centered at both ends and the bend swinging in the center of the spindle. You then rough the chamber with a single point cutter and run the reamer in with a floating holder to follow your newly established line of bore. It also leaves the thread extension parallel to the chamber because you can thread in the same operation. Old Rudy, and I believe Leaper used to fume and spit whiskey over that system even though its a pretty safe way to do things. Rudy called it the question mark chambering method. LOL His analogy I suppose was not far off because when finished the bore and the chamber do rather resemble a question mark as in figure A. He felt the reamer should be dead nuts on straight to the bore at the start and that's why he tried playing with dialing in one end only all of the time. Well we all did for a while until we figured out that simple physics and trigonometry was working against us.

    The old original way was probably the best. Driving the muzzle dogged off and pulled against a center with springs, the barrel floating slightly in the steady rest and the reamer being driven on a center and held with a T handle or vise grips. That allowed the reamer to follow the bore perfectly and the chamber and throat to join more square as in figure B. The reamer nose orbits with the free floating barrel and follows the curve of the bend in the barrel as the barrel turns. Its easy to understand if you take a bent piece of garden hose and stick a screwdriver in one end and use your fingers to simulate centers and spin the two together. That's how I used to show apprentices. Then the light comes on. You can clue me in if I'm wrong but I think Shilen use's or did use this system.

    The system I use today by holding the muzzle and reamers in collets is not far off from what you are doing. The reamer cannot follow a bent bore 100% using this system and I rely on floating the barrel in the steady rest and the flexibility of the barrel to keep the reamer from becoming a single point cutter and cutting an outsized chamber. But in all probability I am cutting a very slight question mark chamber. But its very slight because I know that the barrels I am using have less than .005 of run out to begin with and I am working on centers so I am POSITIVE I am under that .005 inch from the very start. And the barrel is flexing and the reamer is trying to straighten the barrel under the tremendous cutting pressure so it has to be pretty close to figure B.

    I still do chamber some special bench rest jobs with the barrel and reamer on actual centers but I really don't think I gain anything by it. And I certainly can't piss around for an hour each time setting it up. Besides, I think we are really over thinking what is really a lot less critical than we make it out to be. And quit frankly a lot of what we are trying to do is both physically and mechanically beyond our means. I do know for a fact that I can't dial in a barrel by measuring over 2 or three inch's. I tested that until I was blue in the face and gave up on it. By working on centers or (dialed at either end) I know where I stand from the start. It may not be perfect. But its not a guess either!

    gunsmith-rod-henrickson-chamber01.jpg

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    JBCGUNS is offline Aluminum
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    Quote Originally Posted by Swarfboy71 View Post
    How do you indicate the bores at the moment?
    Thanks Guys, I started the thread and left my computer for a few days. Great responses. It's amazing how I always get shitloads of information by asking a simple question. Keep it comin'.
    Swarfboy, the two rebarrells I have done used a plain centreless ground indicator rod about 8" long using the two dial indicator method setup through the headstock with an outboard spider and a 4 jaw chuck (Using offcuts of 1/4" brass rods between the jaws and barrel to allow it to pivot). If my two Mitutoyo indicators are telling the truth, I got that to run within .0002" - .0003".
    I then used a HSS twist drill to Rough the chamber to a depth of about 1/4" short of the shoulder and re indicated to eliminate any movement before using my smallest boring bar to clean up the drilled hole to within about .030" of the reamer body diametre and then reamed with a MT3 mounted floating reamer holder.

    I am moving away from the general engineering side of things and would like to specialise on Guns only in the near future, thus my original question regarding the better indicator rods to purchase. I would like to be able to cover any barrel that came through the door so it was half a question about the economics vs the practicality of the two options.
    Just getting back to that, it seems like most guys are talking up the Grizzly Rods. Any more info about how the pilot set up works with them and if they are interchngable with PTG live pilot reamers etc.? A picture would be nice if anyone has one but a description will do.
    JB

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    Swarfboy71 is offline Aluminum
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    It seems most people like the Grizzly over the PTG rods. I have to admit I like the idea of doing it between centres or a ER collet as Spearchucker does. Makes sense to me.Maybe I am a little old school..... LOL

    What sort of error/repeatability you get with PTG rods? Example set up a barrel 2 or 3 times how close does to come to the same run out? The reason I ask is I was looking to buy PTG rods for clocking barrels with action still attached so I can thread the end with out pulling barrel.

    I have noticed you guys like the Grizzly rod for doing chamber end,what is your preferred method for clocking up muzzle end when it is hanging out the other end of the headstock?

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    300sniper's Avatar
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    i do prefer the grizzly rods over the range rods to help dial in either side of the barrel.

    i use the largest bushing that will freely fit in the bore to keep it from falling in the grooves as the barrel turns. at the chamber end i set the barrel up so the spider adjustment screws are where the reamer pilot bushing will end up when the chamber is at full depth. i start out by adjusting the od of the barrel at both ends to about .001" by hand tightening the adjustment screws on the spiders. i then start with the grizzly rod bushing where the reamer pilot will end up (directly under the spider adjustment screws). i get that dialed in to within a couple tenths. i then move the rod in the bore about 2" forward and dial it in to within a couple tenths using the rear spider. then it's back to the first location and dialed in to within a tenth and 2" forward the same. this may take a few times of back and forth until both locations read less than a tenth on the rod and the spider adjuster screws are snug enough to hold the barrel for machining ops. i double check directly on the lands where the throat will be with my long reach interapid test indicator to confirm it's far less than 5 tenths tir. once that is confirmed i can proceed with the work. after i pre-drill the chamber but before i bore it, i double check with the long reach indicator that the throat hasn't moved. once satisfied that the throat is still good, i bore the majority of the chamber to .010"-.020" under the reamer's shoulder major diameter. i bore it deep enough so the pilot still has a slight purchase on the bore to ensure it starts with a barrelled attitude.

    the muzzle is set up similar except the spider adjustment screws are about 2" back from where the crown will be. i start by dialing in with the rod under the front spider using the front spider to adjust. i then move the rod to the muzzle and adjust with the rear spider. once both spots read better than a tenth off the rod, using a tenth indicator i directly read on the bore to confirm it is within a couple tenths at the muzzle and proceed with the crown.


    when using the grizzly rod, i hang a plumb from the rear of the rod to keep the rod preloaded in the bushing and the bushing preloaded in the bore. i also set my indicator up so it is at the end of the barrel when the rod is as deep as it will be going and the magnetic base is on the tailstock, not the carriage or bed of the lathe. i slide the tailstock back and forth instead of using the quill. this meas that my leverage error on the rod is the same in both spots. if less than one tenth on the rod gets me far better than 5 tenths by direct reading at one spot, i'm pretty confident it will be as good 2" further forward with this setup.



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    Swarfboy71 is offline Aluminum
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    Thanks for explaining how you go about it. What bushings do grizzly rods take? Same as range rods? I have also been looking at deltronic pins. I have to get a 'set' of something as I plan on doing a lot more barrel work.

    Thanks again for the post and pic
    Quote Originally Posted by 300sniper View Post
    i do prefer the grizzly rods over the range rods to help dial in either side of the barrel.

    i use the largest bushing that will freely fit in the bore to keep it from falling in the grooves as the barrel turns. at the chamber end i set the barrel up so the spider adjustment screws are where the reamer pilot bushing will end up when the chamber is at full depth. i start out by adjusting the od of the barrel at both ends to about .001" by hand tightening the adjustment screws on the spiders. i then start with the grizzly rod bushing where the reamer pilot will end up (directly under the spider adjustment screws). i get that dialed in to within a couple tenths. i then move the rod in the bore about 2" forward and dial it in to within a couple tenths using the rear spider. then it's back to the first location and dialed in to within a tenth and 2" forward the same. this may take a few times of back and forth until both locations read less than a tenth on the rod and the spider adjuster screws are snug enough to hold the barrel for machining ops. i double check directly on the lands where the throat will be with my long reach interapid test indicator to confirm it's far less than 5 tenths tir. once that is confirmed i can proceed with the work. after i pre-drill the chamber but before i bore it, i double check with the long reach indicator that the throat hasn't moved. once satisfied that the throat is still good, i bore the majority of the chamber to .010"-.020" under the reamer's shoulder major diameter. i bore it deep enough so the pilot still has a slight purchase on the bore to ensure it starts with a barrelled attitude.

    the muzzle is set up similar except the spider adjustment screws are about 2" back from where the crown will be. i start by dialing in with the rod under the front spider using the front spider to adjust. i then move the rod to the muzzle and adjust with the rear spider. once both spots read better than a tenth off the rod, using a tenth indicator i directly read on the bore to confirm it is within a couple tenths at the muzzle and proceed with the crown.


    when using the grizzly rod, i hang a plumb from the rear of the rod to keep the rod preloaded in the bushing and the bushing preloaded in the bore. i also set my indicator up so it is at the end of the barrel when the rod is as deep as it will be going and the magnetic base is on the tailstock, not the carriage or bed of the lathe. i slide the tailstock back and forth instead of using the quill. this meas that my leverage error on the rod is the same in both spots. if less than one tenth on the rod gets me far better than 5 tenths by direct reading at one spot, i'm pretty confident it will be as good 2" further forward with this setup.



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    ptg makes the grizzly rods and they use ptg bushings.

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    Butch Lambert is offline Stainless
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    Something you need to think about. Everybody here seem to think in terms of the bore being in a curve. Actually more of them are in a helix. The idea is to indicate so the bullet is looking at the middle of the bore. Let me ask this, if a barrel is indicated in the grooves at the throat and taper bored to that point. Use a reamer with a very loose fitting bushing to do the reaming. If you push your reamer with a flat surface in your tail stock your reamer will follow the taper bored hole. Your chamber will be coaxial with your throat. I do not want a tight bushing telling my reamer that it needs to go in a different direction than the taper bored hole. Your muzzle end will not be flopping around either. Speer drew a pic of the bore making a big turn right after the throat and another that followed his idea of the way the bore should go.
    Now you folks that like to do a little trig, it was stated a bore would be out a max. of .004 in a 26-28" barrel blank. We will give it the benefit of being a true arc{which it isn't] and also not a helix[probably]. Approx. how far does the bore run out in .500" after leaving the brass?
    I've done them both ways on my BR barrels and I have seen no benefit in the Gordy Gritter method. It is an OK method, but no better than some others. I believe these discussions make you think and that is good.

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    Well Butch, if it was a true progressive arch, which decidedly it is not, at .500 inch it would be 7.14285714285714E-005. Less than 1/10th of one thousandth of an inch. In reality the numbers are actually to small to measure, to close to cut to and to insignificant enough to worry about. But it is interesting to think about. But with no real way to reliably map the inside of the bore to 1/10th of one thousandth of an inch prior to cutting, its pointless to believe one could take it any farther. All I know for sure is that all of the systems being used today were being used when I got into this game 30 years ago and no one system has ever proved better than the others.

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    speer, from what you posted earlier, i would assume since there was no other reference given, the bore would not be allowed to runout more than .009" over the 29" length between centers. that .009" could be at 14.5" down the bore, 2" down the bore or 27" down the bore. if my assumption is correct, that angle could dramaticly change your .5" infront of the throat runout.

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    hey butch, don't get me wrong, i am certainly not questioning your results because i know plenty of record setting rifles have been built using your method. i am trying to understand why even dial in the muzzle at all when setting up for a chamber. if you two identical barrels (we all know that is impossible but just for this point assume they are) and set up one in the lathe for a 30" finish length and the other for a 24" finish length, won't the chambers be pointing in an ever so slightly different direction? if so, why not just skip dialing in the bore and hold the barrel tight in a set-tru type collet chuck and dial in the throat dead nuts? it seems to me like the end result would be the same for any barrel finish length, the work holding would be much more rigid and it would be much faster. if i am missing something, please let me know. you are absolutely right about these discussions being good. keeps me thinking.

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    Butch Lambert is offline Stainless
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    Have you ever been to a match and your barrel quit shooting? You have a few minutes and put on a new barrel. If your muzzle was flopping when you chambered it, where are you when you go to the line. Only a few thousandths off at the muzzle will put you off the target or God forbid you put a bullet on your record target trying to sight in the new barrel. Must be a reason that the better, winning gunsmiths do not use the Grizzly rod. I'm not saying it isn't the not so good method, but it is not the prefered method of the winning smiths. I have been involved in a fun thing at a major barrel maker's shop. They took a blank off the shelf, chucked it up in the 3 jaw and in the steady rest. The bore was eyeballed and then the tenon was cut and threaded, and chambered. The reamer was held with a tap handle and pushed into the chamber. The barrel was very crooked, but shot lights out. Would it have shot better with a more careful chambering job, maybe?
    We all do it a little differently and each like our own method. I believe a whole lot of it is between the ears.

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