Yesterdays experience dialing in a barrel
Yesterday, like most every Saturday/Sunday i shoot in the morning, and play with my lathe all afternoon. I had a couple projects that i wanted to complete, or at least start. The first project was to learn how to catch a thread on a barrel that wasn't chambered by me. The barrel in question was a bit to tight for my particular action, so i thought this is the time to learn something new. The project turned out really well, and catching an existing thread was quite simple. Here is were it gets interesting though.
While dialing in this barrel i used my Gordy rod as i normally do, or would. Everything was pretty straight forward, but i couldn't get this barrel dialed in any better than about .0006, while using the Gordy rod. Not real sure why i couldn't get better than this, other than knowing that maybe this was as good as my lathe would do, i decided to use a range rod just to see what i could come up with. I took the Gordy rod out, and placed the range rod in. The readings were close but the main difference was, that while using the range rod i could dial in to about .0002 on the test indicator. So now i cant but wonder is the Gordy rod more sensitive, and the better tool to use, or is the range rod? The range rod gave me visual please for sure, but i question its accuracy to a degree. After deciding i was close enough either way, i sat up the threading tool and chased the thread and completed the task with great satisfaction. The barrel now fits the action perfectly.
I will also add that the only reason i bought the range rod was to set barrels forward a bit. My best friend brought his barrel over a couple weeks ago and asked me if i would set it forward and of course i said, sure. I placed his barrel in my lathe and tried to dial in with the Gordy rod. To make a long story short, i wasnt happy with what i was seeing, and decided to hold off the project until the range rod showed up. Like i said before, when the range rod came, i placed it in his barrel and dialed it right in. 10 minutes easy. I set the barrel forward a bit, and his barrel is now back to shooting small groups. Being new to all this, you can probably understand were all this leaves many questions.
Back to the Gordy rod. I know my lathe is a cheap china lathe, but it is what i have at this time. I will add that with the Gordy rod inserted into a barrel i can push on my 4 jaw with my hand and see the test indicator move about .0005. There again is that the difference i am seeing between the two rods, that being the bearings in my machine? Any thoughts? Lee
Sorry for my English and writing skills. A writer or grammar expert, i am not! Lee
Last edited by skeetlee; 07-22-2012 at 12:07 PM.
Your writing is getting noticeably better.
When your are using what you call the Gordy rod, are you letting it float, with no additional weight applied to take up the clearance between the pilot and the rod, and the pilot and the barrel? When I reviewed the video of Gordy dialing in a barrel, I saw that he is reading the rod from the side (I think that that is what I remember.) while others have taken a different approach. They have measured vertically, with a weight hung from the rod to take out any slack, and center it in the bottom of the bore.
It was brought to my attention, that my writing sucks. LOL!! I know it does, but what can i do!! I wont lie. I didnt do very well in English class, nor did i care much, to do well.
Anyway back to the good stuff. I do use a piece of barrel stub as a weight. I hang the weight with a piece of fishing line. I then take my readings from the 12 o'clock position on the Gordy rod. Hope this helps some. Lee
Something occured to me today. Maybe the reason i couldnt dial in 100% with the gordy rod has to do with with the lands in the barrel. If one land was a little taller than the others would that throw off the reading on a bushing? I dont know if this is the reason or not, i am just a little baffled as to my findings. I have a shilen 22cal barrel i am going to chuck up one night this week and i will use both the grizzly rod, and the range rod. I will report what i find. Lee
I also wanted to add that that i bought the range rods to do crown work with. A couple weeks ago i did a little experimenting on the crown of a good solid shooting ppc barrel. The barrel is a Krieger 6ppc that had about 700ish rounds on it, and it was a barrel that i could most always call shots with. Because i have the machines to do my own work, i thought maybe it was time to sharpen the crown a bit. I took the barrel into the machine shop, and on my way there, i thought to my self that this might be the time to try and learn a little something about crowning. What i did was chuck up the barrel in my cheap 3 jaw, and just face the dam thing. no indicating at all. my cheap 3 jaw runs out about .0015 to .002 so it isnt real true. I could see the barrel run out in the chuck, as the lathe was turning, I remember thinking to my self that this isnt going to be good. Since i could see the run out, i figured it had to be more than out just a couple thou. Anyway to make a long story short, i faced it and made sure the crown looked good. Then I took it back to the range and shot it. The dam barrel shot a .162 4 shot group. I thought that this might be a little luck, so i shot another. The second group was a .235 4 shot group. The barrel wasnt shooting any better than it had before, but it sure wasn't shooting any worse.
This little experience got me to thinking that maybe i didnt need to speed 45 min indicating the muzzle in every time i wanted to sharpen up a crown, so i purchased the range rods just to do crowns with. i think it will work out really well to. Also, after i received my 6mm range rod, i set that krieger barrel back up in the lathe and re cut the crown the proper way. I do like to do things properly, or at least to the best of my ability. I do not intend to face another barrel off, like i did with this one, but i did learn that maybe a minor error here and there we can get away with??? As long as we dont make to many errors that is!! I just thought this was kinda interesting. Lee
Last edited by skeetlee; 07-23-2012 at 05:28 PM.
If you are using a "range rod" on an already chambered barrel you are using the wrong tool. You need to be using an "indicator rod".
When weighting your Grizzly rod, make sure your bbl stub you are using is no more than 1 oz. You can cause too much deflection giving false positives.
If you are cutting your crowns square then being dialed doesn't mean near so much. If you are cutting a true 11 degree then being out of square with the last 2" can be quite noticable. The bad thing about range rods is the end your using them in needs to be cut off square and very clean inside or it will just pick up and magnify any defects.
Are you using fit bushings on your Grizzly rod? We use the largest one that fits.
on a 6ppc chambered barrel the range rod works quite well. the 1.5 degree lead is a nice match for the 1.5 degree angle on the range rod and since the 6ppc chamber isnt very deep there is plenty of rod hanging out the back end to indicate from.
Very true!! Thanks Lee
Skeetlee if you using a perfectly flat crown with no taper cut to the bottom of the lands I can see where there might be little difference. If you are breaking the edge at 45 degrees or what suits one best I believe your .002 thousandths run-out would defiantly become an issue. I like to look at achieving extreme accuracy as the process of eliminating variables and go to great means to try and eliminate them. In my mind that .002 thousandths run-out could be introducing one of the numerous variables I go through great pains to eliminate and thus it would not be acceptable in my means and methods.
I don't use the "gordy rod" any more. I got too many readings that were suspect (couldn't believe barrels were that bad) and went back to pins. I suspect that each time the bushing "falls" into a groove the indicator gives a false reading. This is especially bad on 3 groove barrels while not so bad on 6 groove barrels. I also indicate the groove diameter rather than bore diameter when setting up to cut crowns. The bore diameter from land to land has to be the same since it is a reamed surface but the groove diameter is a cut surface which could vary a bit from barrel to barrel. When cutting chambers I indicate the bore diameter since that is where the reamer bushing will ride. I really can't tell if it makes a difference or not.
Please dont miss understand me. I also dial my muzzles in to the very best i can. I was just curious, as i offten am, so i tried cutting the crow without dialing anythng in just to see the results. I used my import 3 jaw that has around .002 run out or whatever so i assume the muzzle also had the same .002 after i faced it. With the straight faing cut, the bam barrel shot like a hammer, it truly truly did!! After i was done with my little experiment i dialed the muzzle back in with a range rod and re cut. The barrel still shoots like a hammer.
We have a small 12 shooter or so local score match here at home once a month, and 2 of my barrels shot perfect scores today at 200, and tied for first place so i must be doing a little something properly, or better yet maybe i am just getting lucky. LOL!!
I will also add that the very first new barrel i ever chambered, my tail stock was broken and i didnt know it. The tail stock once dialed in would stay dialed in. and would go as much as .040 out That barrel i chambered with the tail stock all out of whack is one of my very best shooting barrels i have. Makes a guy wonder about some of this stuff. I DO however try very hard and i take a lot of pride in my barrels. Makes a guy feel pretty good when a barrel you chambered shoots well or better yet wins a shoot. Lee
Skeetlee I have been tracking your progress with your new Lathe and being somewhat new to doing my own work as well I find your questions to be very interesting and I admire the passion you have to accomplish things to the best of your ability. My lathe was one of those best money spent items and being a cast bullet single shot falling block rifle competitor ( Schuetzen ) it has also came in handy to create some of those peripheral items that one uses in our sport and the mind is the limit.
Now to save enough money to come up with a Mill.
Your Gordy rod is picking up the indicated runnout at the location you are testing at. The bore is not perfectly straight (can not gun-drill perfectly straight holes) so as you work gordy rod in it is going to change. Unless your getting runnout without working the gordy rod then you have other issues. The tapered range rod is averaging between two points in the bore. The range rod is easy to dial it in, however, it is not the ideal dialing method and will yeild a non-uniform blendout in the lead. You need to experiment here.
I beg to differ with your comment that it is not the ideal method.
Originally Posted by skeetlee
Trying to do any sort of barrel 'thru the headstock' dial-in type work will drive you insane if you have a cheap/worn lathe with crappy headstock bearings. This is where the difference in a quality verses cheap machine will really show up. Also you need to run your own tests on the lathe to ensure that the centreline central spinning axis of the spindle actally is running true with the lathe bedways (when tested with a DTI and a hardened & ground test bar, and not just what it will machine/turn a soft 'test bar' of steel or alloy to). Then once you have got all that sorted out, also ensure that the tailstock is correctly aligned as well just as a bonus.
The errors/irregularities in the readings when using the G-rod (assuming you are also using a high quality indicator, like a 1/10000th mitutoyo or better) may well be due to problems with the top of the rifling (land) form - common problem on some button rifled barrels where the land tops are not flat but 'dished' and the edge of a land may have a slightly high 'ridge' on it, or running a pilot with too much clearance. About 0.0002" under a just slip fit usually will work out ok. BUT, the biggest issue i think you face it likely the spindle bearings in your machine. All of the types of indicator rods have their pros and cons. I did notice Nate had a good idea for one with two bushings on it, but I don't know if there are any issues in practice with that due to the clearance/play in the fit of the bushings to the rod?
Last edited by kiwi smith; 08-21-2012 at 06:50 AM.
I have checked my centerline, and my bearings are actually quite good. I also adjusted my head stock to run true. All that has been done. One thing i did do wrong when i first got my machine was that i got into a big ass hurry to chamber a barrel and i built my front spider wrong. I didnt at the time have a turn table for my mill and when i drilled the 4 holes for my spider screws. my holes were not exactly true to one another. With the jack screws not being true, the screws would push the barrel in different directions, and dialing in was a chore. The funny thing is, and i still cant make heads or tails of any of this is that the first barrel i ever did, i had a lot of things wrong with me and my set up. The tail stock was way off, my spider wasnt made right, and who knows what else. That first barrel i did is a shooting SOB and i am not even kidding. Go figure that one, i know i sure cant.
I have then since made a new spider, and my tail stock is dead nutz, and the barrels i am chambering still shoot lights out. So far!! Well not counting one button barrel that is now being replaced from the manufacture. That barrel didnt shoot, but all others i have chambered are doing really good. I do like the range rod compared to the grizzly rod. I do think the grizzly rod may be a bit more accurate, but how accurate do we really need to be. Most machines wont run to the degree we would like them to run. If i can get my range rod to read .0003 to .0004 on my test indicator isnt that actually half that amount anyway?? I dont beleive that my china made machine can even run at these tolerances. Any thoughts?? Lee