WSnyder
Silver $$ Contributor
Sink a neodymium magnet into the block.
Indicating & reaming throat under jaws/spider
- Thread starter Henryrifle
- Start date
Alex Wheeler
Site $$ Sponsor
I also stay away from soft materials. The whole point of a sacrificial material is to compress. Thats probably the main reason barrels move during the machining process.
So is this unacceptable in the big scheme of things?
Dusty Stevens
Shiner
On the internet yes
This is fine IMO, but unless all of your barrels have identical shank diameters and no taper I don't see it as any different than the V-blocks that I use. You're still only getting two points of contact unless the radius block and barrel diameters are identical. In any case, I replaced the flat brass tips on the spider screws with ball bearings and v-blocks after my first time using the inboard spider.
It was obvious to me at that time that a rigid flat (brass tip) on a round surface did not/cannot allow the barrel to gimbal freely. I was forcing/bending the barrel into place. With ball bearings/blocks, you can easily pivot the breech around in a full circle with light finger pressure on the muzzle- try that with the flat brass tips.
Having the blocks captured to the ball bearings would be nice, but it's really no big deal placing them.
True.
I usually just grab the barrel in the outboard then run the TS with a center against the barrel. Tension a little, putting the pads is quick and easy, renders the barrel in the front roughly centered. Dial the outboard, etc..
Damn...amazing how the obvious escapes me sometimes
.... perfect way to get them close to center in no time.
Dusty Stevens
Shiner
Now thats a chuck!
Rohm's and Kitagawa chucks are top of the line for repeatable precision.
I put the barrel in, then put a 1" dial indicator on the muzzle end and adjust to within .001" runout with the outboard spider. Then I move the 1" indicator to the inboard spider and do the same for the breech end. This takes very little time and ensures the barrel starts pretty straight before I dial in the throat and breech with the Interapid. Whenever I release one of the spiders after dialing in fully, the barrel stays centered.
No, I just sourced the metric flange bolt so I can uses a short box end. The Rohm use M10 or 12, can't recall. I wanted to use 12 point bolt, could not find the size at that time.
I do use 12 point bolt to drive the pads on the outboard. Those tiny 3/8 12 point box ends are easier to use than Allen driving socket heads.
I really like the brass blocks that are always shown when this topic comes up. Since I am not a machinist it would put me behind to stop and make some. That said, my brass tipped screws on aluminum shims seems to work well enough.
On occasion I have to tweak my dial-in when I recheck after threading and immediately before chambering. Like I posted earlier, I don't notice any tight spots in the bore under my shims when fully dialed-in.
The hunting rifles I chamber commonly shoot 3" and better 3-shot groups at 650 yds, and my LRBR guns shoot screamer groups on occasion and I seem to do well enough in competition unless I do a dumb stunt when tuning or miss a wind change during the record group.
To me that is validation of my methods. And no, I expect to keep tweaking my methods as I find better ways to do things.
There are lots ways to do this, and we all need to find the way that we think is best. I suspect most of here have thoughtfully and systematically worked though our process, and regardless of the final method, if we are thoughtful and systematic we will get good results.
On occasion I have to tweak my dial-in when I recheck after threading and immediately before chambering. Like I posted earlier, I don't notice any tight spots in the bore under my shims when fully dialed-in.
The hunting rifles I chamber commonly shoot 3" and better 3-shot groups at 650 yds, and my LRBR guns shoot screamer groups on occasion and I seem to do well enough in competition unless I do a dumb stunt when tuning or miss a wind change during the record group.
To me that is validation of my methods. And no, I expect to keep tweaking my methods as I find better ways to do things.
There are lots ways to do this, and we all need to find the way that we think is best. I suspect most of here have thoughtfully and systematically worked though our process, and regardless of the final method, if we are thoughtful and systematic we will get good results.
AckleymanII
Gold $$ Contributor
I create a pivot point at my throat location.
Check run out after cutting tendon with Interapid 2.7"
Check after threading
Check after chambering
I do not want the outboard spider bending the barrel. .0003 throat run out on a finished chamber is as big as it ever gets with zero to .0001 being the norm, Buck 6 jaw chuck. Heavy cuts on threading/turning are where my run out comes from, Alex hit the nail on the head.
Last edited:
I go through all the troubles, and what is the 1st match the barrels are shot in? 200 yards standing...
On a serious note, we will test the barrels I just finished for the TX Juniors. Test bed is Remington action with a front end to screw an AR15 barrel. Mounted on a machine rest. Pictures were taken during fit up and initial testing.
On a serious note, we will test the barrels I just finished for the TX Juniors. Test bed is Remington action with a front end to screw an AR15 barrel. Mounted on a machine rest. Pictures were taken during fit up and initial testing.
Speaking of tweaking our approach. I have watched Bruce Thom set up our Kingston HJ1100 to cut chambers. Everything on that lathe is top notch from the Bison Set True to the Walter inserts. It is aligned perfectly and it cuts a beautiful chamber.
The set true chuck is very appealing. You get full grip of three jaws on the barrel shank, so it doesn't move. Bruce doesn't use any kind of protective wrap on the barrel, so there are always light marks on the shank from the chuck jaws. However, that setup never moves. As long as the barrel is bead blasted the marks are no issue. If you have a customer that doesn't want any finish on the barrel, then that's a problem.
I guess when you are gripping 2" of barrel shank with chuck jaws, the barrel really can't articulate like it can with a dual spider system. Even when it's a Bison Set-True. That whole 2" shank section is going to move with the Set True adjusters, so if that section of the barrel isn't straight there is no adjusting it. Then again, If you dial the throat area and prebore, that won't matter.
The set true chuck is very appealing. You get full grip of three jaws on the barrel shank, so it doesn't move. Bruce doesn't use any kind of protective wrap on the barrel, so there are always light marks on the shank from the chuck jaws. However, that setup never moves. As long as the barrel is bead blasted the marks are no issue. If you have a customer that doesn't want any finish on the barrel, then that's a problem.
I guess when you are gripping 2" of barrel shank with chuck jaws, the barrel really can't articulate like it can with a dual spider system. Even when it's a Bison Set-True. That whole 2" shank section is going to move with the Set True adjusters, so if that section of the barrel isn't straight there is no adjusting it. Then again, If you dial the throat area and prebore, that won't matter.
Dusty Stevens
Shiner
Be careful with them bolts sticking out if youre not used to it. A good short hex key and flush bolts are the safest way. If they dont move crack those bolts in the front a bit more
Something like that but two pieces like a ball clevis so barrel can rotate freely till final tightening would be interesting
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.