Barrel coming out of alignment during threading

[DaveTooley]

Also, From what you are explaining? It sounds like you are cutting a taper? Have you checked your headstock for alignment?

I believe his numbers came from the rod not the threads.

 

[Blair Mason]

Corre

I believe his numbers came from the rod not the thread

Correct

 

[Blair Mason]

I will check this, thank you.

 

[Alex Wheeler]

my experience with rods is that every time you take it in and out you will see a different number. So that may be your whole issue. Some guys use them to get close, but you can just dial the od of the barrel to get close enough to put the indicator in the bore. Plus you learn so much about the barrel with an indicator. You learn nothing about it with a rod. Not a fan of them.

 

[Blair Mason]

Thanks for all the input. I will work on using a long reach DTI to indicate instead of the rod. Taking the spider screws all the way loose and retightening seemed to “settle” things in a little bit.

 

[DaveTooley]

Thanks for all the input. I will work on using a long reach DTI to indicate instead of the rod. Taking the spider screws all the way loose and retightening seemed to “settle” things in a little bit.

I dial both ends in not much more than finger tight to within a few thou. By then I have a target number on the indicator. Only then do I increase torque in small increments going from screw to screw until I get the pressure I want.

 

[Alex Wheeler]

Thanks for all the input. I will work on using a long reach DTI to indicate instead of the rod. Taking the spider screws all the way loose and retightening seemed to “settle” things in a little bit.

Most people use spiders incorrectly. They are not to push the barrel into position, they are there to hold it. They are not jacking screws. Used correctly they do not flex the barrel or induce any stress. If a barrel is moving in the setup its probably because its under stress. What I tell guys is if you loosen the outboard spider, the inboard side should not move. In fact I remember chambering a 300 win mag. Cut the tenon and threads, then went to hook up my flush on the muzzle and noticed I never tightened the outboard spider. All 4 were not even touching the barrel. When I checked the inboard side it was within .0003". Not bad for only one spider holding it.

 

[Sniperhandle]

Ummm I would have never thought of that.

Sometimes even a "Dummkoph" like myself has something to contribute! Here is my #5 MT test bar I use to dial in the headstock.

​

 

[WSnyder]

For the short length of the tenons we cut how much do we care if there’s a slight taper or not? And to channel my inner @butchlambert same question for a worn bedway?

 

[DaveTooley]

I've got two 48" 1 1/4" Thompson bearing rods. I've considered dialing those in on each end of the spindle then seeing what the runout is 16"-18" out. Trouble is I not sure I want to know. I've got the specs that came with each lathe and they're pretty good.

For the short length of the tenons we cut how much do we care if there’s a slight taper or not? And to channel my inner @butchlambert same question for a worn bedway?

And with turning and threading we get work piece deflection which induces a taper. I've never seen it show up on a target.

 

[LVLAaron]

Trouble is I not sure I want to know

Same.

 

[Walt Krafft]

Look up Calvin & Hobbs "Ignorance is Bliss". It is a favorite of mine.

 

[55fairlane]

Ok here is a question, I ask this because I haveva lathe at work with junk headstock bearings.....are your headstock bearings loose? Not lubricated? Worn to the point that any load on the bearings cause run out? Or is your chuck not registering on the spindle well?

 

[Dave Zander]

We would chuck us stout piece of bar stock , take a light cut on the O.D. If the headstock is out of alignment the diameter will have taper in it . Could have loose or worn spindle bearings also. If your turn diameter isn’t round your spindle bearings could be loose.

 

[Sniperhandle]

Ok here is a question, I ask this because I haveva lathe at work with junk headstock bearings.....are your headstock bearings loose? Not lubricated? Worn to the point that any load on the bearings cause run out? Or is your chuck not registering on the spindle well?

I just finished replacing the headstock bearings in a lathe I picked up cheap because the original owner did not read the manual, He put 90 wt gear oil in the headstock and it fried the bearings because its a splash system and the ISO 68 spindle oil is only around 20 wt oil. I know the old school lathes ran 90 wt gear oil, But these newer ones run a light hyd type mineral oil. Make darn sure you follow what the manual says, A days work and some expensive Japanese precision bearings will be in your future if you don't.

 

[Blair Mason]

Any suggestions for a long reach indicator?

 

[Sniperhandle]

Any suggestions for a long reach indicator?

Interapid and you are looking at around $450.00 Ask LVLAaron what model # he uses.

 

[WSnyder]

Any suggestions for a long reach indicator?

Interapid 312B-15 2.75” stylus

MIT 513-512 1.47” stylus. .0005” indicator. Small body can reach up into chambers.

MIT 513-504 .75” stylus. .0001” indicator. Small body same as 513-512. Works great for shorter cartridges like BR and PPC to reach throat.

 

[Judd]

Interapid 312B-15 2.75” stylus

MIT 513-512 1.47” stylus. .0005” indicator. Small body can reach up into chambers.

MIT 513-504 .75” stylus. .0001” indicator. Small body same as 513-512. Works great for shorter cartridges like BR and PPC to reach throat.

Great recommendations…but I suggest getting the 312B-15V. The 15 without the V is backwards and if you’re not a machinist and used to dealing with indicators it will drive you insane.

I tried it on three different barrels because it’s nice but caught myself from throwing it across my shop more than once. I would move the barrel the opposite way needed and it always seemed like right when I got it close. I ended up trading it for a barrel, just to keep from smashing it with a hammer haha.

The 513-504 is what I use most of the time now and I’ve bought a longer stem for it.

 

[LVLAaron]

The MIT 513-504 w/ a 1.47 inch stylus is the best bang for the buck.

The Interapid is like a Swiss watch... It will make the perfectly fine Mitytoyu feel like a cheap Chinese tool.

BE SURE to get one that comes with and is intended to use the long indicator. I've seen some people get the model that comes with a really short stylus, and then stick the 5 inch stylus on it... makes it basically worthless.