Centring barrel in 4 jaw chuck
- Thread starter Rotaxpower
- Start date
unstableryan
CGN Ultra frequent flyer
- Location
- Beautiful Okanagan Valley
We just use a magnetic base and a dial gauge for the 4 jaw... are you trying to do something harder than that?
The way Ron Smith (the barrel maker) told me to do it was dialing it in by putting a dial indicator 1/4 inch into the bore and trueing off the top of the lands. I used this for both chambering and crowning and it always seemed to work well. Concentricity of the fired cases was just excellent plus Ron knows way better than me!
I like the idea of the test indicator finger in the bore and checking the peaks.
But if one wanted to use a plug that extends out so a regular plunger style dial gauge can be used there's no reason why it has to be expensive. You've got a lathe for doing the barrel work, right? So turn a plug from brass or aluminium that is a snug finger pressure fit into the bore. No cost other than a few minutes and some small scraps of metal.
But if one wanted to use a plug that extends out so a regular plunger style dial gauge can be used there's no reason why it has to be expensive. You've got a lathe for doing the barrel work, right? So turn a plug from brass or aluminium that is a snug finger pressure fit into the bore. No cost other than a few minutes and some small scraps of metal.
Blastattack
CGN Ultra frequent flyer
- Location
- Winnipeg MB
I hope this isn't a dumb idea...
Could you pound a bullet (projectile only, NOT a full cartridge) into the bore, leaving enough protruding to dial off of?
You wouldn't have any control over concentricity trying to do that.
just having some fun
CGN Ultra frequent flyer
no the bullet method will not work
If you take a chunk of lead and hit it a hammer it will not be close to it original shape
Indicating off the center will get you the closest
I have talked to one gunsmith and he uses a finger indicator 4 decimal places 0.0001 +-
If you take a chunk of lead and hit it a hammer it will not be close to it original shape
Indicating off the center will get you the closest
I have talked to one gunsmith and he uses a finger indicator 4 decimal places 0.0001 +-
Short dial in the bore works ok.
Dial with a long pointer and a spider on the rear of the lathe so you can dial 2 spots (further apart the better) and make both spots run 0 works better.
Range rods Makes it easier and faster. Lots of different bushings for a snug fit helps.
SSG True bore alignment makes it really fast and easy. It has an excentric and a four jaw built in so you can adjust both axis and then snug the spider with no stress on the barrel. Take a look http://www.straightshotgunsmithing.com/page25
Dial with a long pointer and a spider on the rear of the lathe so you can dial 2 spots (further apart the better) and make both spots run 0 works better.
Range rods Makes it easier and faster. Lots of different bushings for a snug fit helps.
SSG True bore alignment makes it really fast and easy. It has an excentric and a four jaw built in so you can adjust both axis and then snug the spider with no stress on the barrel. Take a look http://www.straightshotgunsmithing.com/page25
Thanks for the help guys, once I get some more time behind my lathe I will give it a go.
Well obviously I have not worked on a barrel yet, but you need to start some were. The research I have done I was told that range rods are ground not something spun up in a lathe. Some times people who post stuff like you should realize that you were once new and had to learn as well. Giving smart answers like yours does do nothing to help. Please keep your comments to yourself next time.
Well obviously I have not worked on a barrel yet, but you need to start some were. The research I have done I was told that range rods are ground not something spun up in a lathe. Some times people who post stuff like you should realize that you were once new and had to learn as well. Giving smart answers like yours does do nothing to help. Please keep your comments to yourself next time.
Rotaxpower,
Good for you, it will be a rewarding learning experience. It is quite easy to make up an indicator rod with your reamer pilot bushing. Turn the end of a piece of 10 or 12 inch drill rod to fit the pilot bushing ID. Slip an o-ring over the other end and support it with your tailstock chuck. Slide the tailstock over and insert the bushing into the bore. Mount a dial indicator with a flat anvil on your cross slide and indicate the rod close to the barrel. Disengage the drive and rotate the spindle by hand to measure runout and make your adjustments.
Pete
Good for you, it will be a rewarding learning experience. It is quite easy to make up an indicator rod with your reamer pilot bushing. Turn the end of a piece of 10 or 12 inch drill rod to fit the pilot bushing ID. Slip an o-ring over the other end and support it with your tailstock chuck. Slide the tailstock over and insert the bushing into the bore. Mount a dial indicator with a flat anvil on your cross slide and indicate the rod close to the barrel. Disengage the drive and rotate the spindle by hand to measure runout and make your adjustments.
Pete
