Not this question again. Accuracy of gritters rods

[Shawnba67]

My dad retired from tool making recently and I can have his indicators. However he doesn't have anything with a long indicator. How accurate can you indicate with the rod and bushing method compared to say the blow whole weeks paycheck, let your broke a$$ eat the yard grass interapid 312b-15

 

[swd]

This is one of topics guys guys argue until they're blue in the face...
Personally I say spend the weeks pay and you'll never regret it. Catch it when MSC has a sale. Get on their email list for special discounts.

That being said you can build sub half inch guns all day long with rods. Heck many many years ago I was originally taught the 60 deg centers on the barrel were the most accurate place to go off of and I built some really great shooting guns like that. I've come a long ways since then...

 

[Steelnecktie]

With a floating reamer holder, it doesn't matter which method you use.
I use a long reach indicator, I have tried the rod/bushing thing, always about .001" to .0015" off of being repeatable. The indicator is more accurate.
If you are clocking barrels, you have to do it with indicator, you will never find 12 O'clock with rod/bushing method. If you pull rod out and stick it back in, everything has changed.
Like I said, if using a floating reamer holder, it doesn't matter.

 

[GenePoole]

FWIW, I use rods and I find them very repeatable. You have to spend a small fortune in bushings to cover all the slight variations, but I think most problems people have with repeatability is not selecting the correct bushing. I have found slightly out-of-round rods before too. The manufacturer (PTG typically) is will usually happily replace them.

I always follow up with a quick check using a long-reach indicator. You don't need to break the bank for an Interapid either. I paid less for four (NOS or very good used) Brown & Sharpe tenths indicators than a single Interapid. The B&S indicators will take a long reach rod; B&S make a 1 7/16 inch rod, but you can also modify a 2 3/4 Interapid rod to fit if you need the longer reach more than the accuracy. The B&S indicators use a M1.4x0.3 metric thread. Dies are available

 

[Danny1788]

so I bought a mitutoyo .0001" indicator with a .5906 length rod and added a 2.75" rod and I did the math and found that my .0001" indicator has turned into approx .00045" indicator now with the long reach rod which is the same as the interapid 312b-15(.0005" with the 2.75" rod). AND I paid a lot less than that for the mitutoyo indicator and longer rod. Just an idea like Gene has already said. I have used the rods and they work I just use the long reach indicator now and it works very well.

 

[Shawnba67]

Thanks I hadn't considered modifying a tip or even adding one Those are both good ideas thank you

 

[butchlambert]

I don't like a long reach indicator stylus. Too whippy and jumpy for me. After indicating at the end of the barrel with a Deltronic Pin, I predrill. I then use a Mitutoyo 513-504 tenth indicator with the 1/2" stylus and run the indicator into the throat. This indicator has a long thin body and will go into the barrel. No, I'm not talking 22LR body size. The setup is much more rigid. I indicate the throat, not 3" down the barrel on my BR and PPC chambers.

 

[ridgeway]

I don't like a long reach indicator stylus. Too whippy and jumpy for me. After indicating at the end of the barrel with a Deltronic Pin, I predrill. I then use a Mitutoyo 513-504 tenth indicator with the 1/2" stylus and run the indicator into the throat. This indicator has a long thin body and will go into the barrel. No, I'm not talking 22LR body size. The setup is much more rigid. I indicate the throat, not 3" down the barrel on my BR and PPC chambers.

Butch...have you tried the Interapid that is made for the long stem? There is more preload pressure on stem and don't jump like you are describing. I know what you mean...they do jump like crazy if you take a short stem indicator and screw on a long stem.

 

[geo.ulrich]

Also if you do not have indicator probe centered to bore it will give you vibration. I'll stay out of the changing probes discussion its been talked to death by to many people with no experience and no understanding...

 

[butchlambert]

I do have an Interapid as mentioned above. Alex is right on the indicator rods. I don't need a long reach stylus with the Mitutoyo as it will reach the throat with the short stylus. Now, I am putting a barrel in the lathe at this time. It will be a 300 Win Mag hunting rifle on a Montana 1999 receiver. I will indicate each end with the Deltronic Pins, predrill and reach in as far as my setup will allow with the Mitutoyo, about 1.600". This will be plenty close for a hunting rifle. I will finish drilling if the indicator says it's good. If not I will straighten the drilled hole with a 1.5deg taper bore to the diameter of about .oo5 under reamer size. I can ream the chamber from there or using the bored hole, I can drill a little deeper to about .050 short of the shoulder. The taper bored hole will guide the reamer.

 

[Alex Wheeler]

One thing I can ad is it definitely matters how well the bore is indicated. The bushing will not make up for slop in indicating. It will only keep the reamer so centered, maybe within .0005" And with the freebore diameter only .0005" over groove depth (usually) theres enough slop there to allow for a throat thats not even cut on one side. The reamer wants to center in the spindle of the lathe, so your bore had better also be centered there. If you indicate right you wont even need a bushing.

 

[butchlambert]

Alex is correct, if your indication is good to the bore and your predrill and prebore, I then use a loose bushing so it won't influence the direction of the reamer.

 

[Cloudrepair]

As a machinist I haven't tried the rods mainly because I haven't seen a reason to.
I have and use all the Indicators mentioned and use my mitutoyo and long stylus tip interapid .0001 (.00045 after long tip added) the most.
the one thing I would like is a bigger ball tip (.118 ) on the long stylus.

 

[Gundoktr]

I tried the rods, same problem, could not get decent repeatability

 

[ridgeway]

They sure make a nice bushing holder when sizing up a bushing. This is the only use I use mine for.

 

[AndyA]

Can someone tell me what drill "wander" is if it only follows the center of the spindle?

 

[Alex Wheeler]

Can someone tell me what drill "wander" is if it only follows the center of the spindle?

The drill wants to follow the center, but if its not sharpened perfectly or does not start right, or the steel has some hardness variation it can walk. Drills see to be much worse than reamers in this regard.

 

[bigngreen]

I get along very well with the Gordy rod, I've proven it repeatable in my set up and for me it's easier and faster especially since I mostly do 5R barrels, I also really like the long stem indicator as well because a direct read is the authority but I don't find myself changing anything. The range rods for me will only repeat to about .003 and they are handy to have around but I will not do any work based of them.

 

[muley]

Hey All. I use GG rods, sometimes you need put a little bend in them to get them to read good. Then you can quickly get close and pre-drill. Then use the Mitutoyo short stem and/or then long reach Interapid to get it as close as possible to dead nuts (this takes the most time for me) then pre-bore. Recheck everything again to make sure still aligned and finish up with the reamer. I have attended Gordy's chambering class well worth it.