Gunsmithing Use of Range Rods to indicate

[GasLight]

Hello all, I am sure I will get several opinions, and I welcome them all.

I was previously under the impression that when indicating a barrel using a range rod, I would simply pick the best bushing and then slide it in until the rod catches the lands on the taper. Then I would position an indicator close to the barrel to make sure it is centered, and then one further to adjust run-out with the rear spider.

Well, I just watched the video that Gordy Gritters did, and he moves the range rod's bushing in and out and keeps an indicator at one spot. He has the range rod chucked up in his tail stock.

What method do you use? One of these or something different?

Dave

 

[Mgordon]

Re: Use of Range Rods to indicate

I have tried both, but I prefer the range rod method to the way Gordy does his.

When Gordy does his, he uses the "Gordys Grizzly Rod" just like a long stemmed indicator. You have to have pressure on the bore from the rod to get a reading. I have tried it over and over and I can never seem to get things right. Plus you need to worry about tailstock alignment and how you hold his indicting rod with your drill chuck.

When using the Gre Tan or PTG (Same i'm sure) rods, you just match up the correct bushing that centers the front of the rod in the bore, then slide it in until the 1.5 degree taper bottoms out. Then just put 2 indicating rods on. One by the chamber end and adjust this one with your 4 jaw, put the second on the right side of the rod and adjust this one with your spider. Remember, the barrel must be allowed to pivot on the 4 jaw to get correct indication, if not, your just torquing the barrel around.

 

[GasLight]

Re: Use of Range Rods to indicate

That is the exact method I have been intending to use, when I watched Gordy, it looked somewhat overly complicated and very dependent on the tailstock being perfectly aligned. I appreciate the input!

Dave

 

[zenbiker]

Re: Use of Range Rods to indicate

Ditto Mark's setup, you absolutely need two indicators on the range rod in the muzzle. Don't worry too much about the spider end, I usually just inidicated on the barrel in front of the acion. Since the bore may not be absolutely straight, getting the muzzle exit indicated as close to dead nuts as possible is the name of the game, and only one indicator isn't enough if it's in the node of a wobbly range rod.

 

[GasLight]

Re: Use of Range Rods to indicate

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 1ZNUF</div><div class="ubbcode-body">Ditto Mark's setup, you absolutely need two indicators on the range rod in the muzzle. Don't worry too much about the spider end, I usually just inidicated on the barrel in front of the acion. Since the bore may not be absolutely straight, getting the muzzle exit indicated as close to dead nuts as possible is the name of the game, and only one indicator isn't enough if it's in the node of a wobbly range rod.</div></div>

I am not sure I follow you here. How do you adjust out the run-out without the spider? What do you mean by 'the node of a wobbly range rod'?

 

[gamma]

Re: Use of Range Rods to indicate

I only ever used one indicator with a range rod but effectively I was using two. I use the same method as Mark. I indicate one end then move to the other end and back and forth like that till the two ends of the rod are bang on 0.000. The end of the rod closest to the chuck is dialed in by the four jaw chuck, the end furthest away from the chuck is dialed in by adjusting the spider at the back of the headstock.

 

[wnroscoe]

Re: Use of Range Rods to indicate

I use the range rod method like Mark shows above. Whether you use two or just one indicator make sure you're indicating both ends of the rod. Just an FYI, dont get your indicator any closer than .500" from the end of the Range Rod, this is where the driving dog was placed during their manufacture and may give a slightly false reading. This per Dave Kiff at PTG.

 

[300sniper]

Re: Use of Range Rods to indicate

i want to try the gordy gritters method. the tailstock alignment doesn't make any difference with gordy's method. in fact, i can see some benefit to the tailstock not being perfectly aligned so there is a preload on the bushing. i will make my decision on this method once i actually try it but i really think there is some merit to it.

 

[RWSGunsmithing]

Re: Use of Range Rods to indicate

Gordy's method does not care if the tailstock is in alignment or not. I spoke with him soon after the dvd was released and he stated that for a experiment he actually bent a rod slightly to see if it made a difference and he told me it did not.

 

[selfbowhunter]

Re: Use of Range Rods to indicate

i have had fine luck using a test indicator inside the bore. US HANDGUNNER, is that aluminum strap you are using in the chuck? how does the flat surface allow the barrel to pivot? i have used weed eater string and short pieces of brass brazing rod and both work well. i would really like to make a collet with internal raised surfaces like mike bryant uses but i havnt tried to make one yet.

chuck

 

[GasLight]

Re: Use of Range Rods to indicate

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body">i want to try the gordy gritters method. the tailstock alignment doesn't make any difference with gordy's method. in fact, i can see some benefit to the tailstock not being perfectly aligned so there is a preload on the bushing. i will make my decision on this method once i actually try it but i really think there is some merit to it.</div></div>

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RWSGunsmithing</div><div class="ubbcode-body">Gordy's method does not care if the tailstock is in alignment or not. I spoke with him soon after the dvd was released and he stated that for a experiment he actually bent a rod slightly to see if it made a difference and he told me it did not. </div></div>

After reading these two posts, I thought about it a bit more, and agree completely. I am still planning to use the two indicator method with the shorter range rod, but who knows, maybe I will give that way a try too...

Thanks for the input, if someone does it even differently let me know!

Dave

 

[steelcomp]

Re: Use of Range Rods to indicate

How many times through the threading steps to you re-check this runout? Cutting the step for the threaded portion can induce some pretty decent loads on the barrel, even if taking small cuts. I can see that cranking down on the chuck probably isn't ideal, so are you taking a risk of -even the slightest amount- spinning the barrel some? If that happens, I'd think all your indications are going out the window since I'm sure some of you guys are working to tenths or even .000050. Do you just have to really take your time when cutting? Cut, check, cut, check...?
Obviously a gunsmith newb here, just not to machining. This is all fascinating to me. Thanks for the great info.

 

[wnroscoe]

Re: Use of Range Rods to indicate

The threads that are used on rifle barrels are "Unified V" threads and are self centering. Usually cuts of .005" or less are taken and final cuts of tool pressure only are used for final fitting. After the threads are complete, bolt nose recess is cut to spec and the receiver will screw on and lock up I re-indicate/check the barrel to make sure nothing moved. If a small adjustment is required I touch the barrel shoulder with the cutting tool prior to chambering.

The thing to remember is this, we're only human and we're only going to get it so close. The floating reamer holder will allow the reamer to cut and follow the bore dead true. When .0001" indicators, range rods and floating reamer holders are coupled in the process, good things happen down range. Hold your tolerances as tight as you can and it'll all be good.