update: rigid reamer holder

[WSnyder]

uses a bushing to support the muzzle in the spindle with no indication. How many here think that that's the best way?

Jackie Schmidt has won a lot with a long head-stock lathe with the muzzle of the barrel in a bushing in the spindle. I think Shelley Davidson had a horizontally adjustable centering device for his big lathe. He wasn't a world beater but he did pretty well. There were others in the past that did similar that I've mostly forgotten.

 

[Ksracer]

Before you do it buy yourself a MT parallel Rod and put it in your tailstock and indicate it's length on 2 axis and then extend the quill and repeat in various locations. I did. . . . .then went down a rabbit hole of line boring my tailstock and making an oversize quill to suit.

That's pretty much what I did, except I scraped the bottom of the tailstock to improve the contact and then shimmed the upper casting into alignment. I should probably check it again, but when I was done there was about .0005 difference between floating on the ways and locked down, and there was no measurable difference between lightly and fully locked down.

I might add that before you indicate a rod in the tailstock, you should mount one in the chuck and check your spindle to bed parallelism also.

 

[LVLAaron]

You could bore it undersize by .006-.008" and finish ream with an on-size reamer. That'll give you a touch of leeway for error when boring.

That spherical adjustable tool holder in the SAC video is very similar to a production toolholder my buddy has used on his bigger HAAS lathe in the turret. I wonder if SAC got the idea from one of those?

I might give this a try. Can't hurt. I'm curious if it makes using my carbide reamer(s) less finicky

 

[X Count]

Jackie Schmidt has won a lot with a long head-stock lathe with the muzzle of the barrel in a bushing in the spindle. I think Shelly Davidson had a horizontally adjustable centering device for his big lathe. He wasn't a world beater but he did pretty well. There were others in the past that did similar that I've mostly forgotten.

Not saying it can't be done and isn't capable of winning but there are many people that say you must indicate at the throat and then directly in front of the throat and let the muzzle go where it needs to. Not indicating in front of the throat, only aligning the muzzle and then pre boring and rigid reaming would be about the worst way to get the bullet started straight in the first part of the barrel

 

[WSnyder]

Not indicating in front of the throat, only aligning the muzzle

I certainly wasn’t referencing anyone that didn’t indicate the throat and Jackie most definitely indicates the throat and I’m sure Shelley Davidson did too.

 

[INTJ]

Lot of naysayers but the designer/builder of Bat actions says it's the best way.

They don't really say it's the best way. They say its the best way for them to make their big lathes work. Bruce and Daryle like big lathes and their method works well enough.

Bruce and Daryle are master machinists and exceptional individuals, and they have zero issue with how I dial in--straight from just ahead of the throat to about 1/2" in front of the breech. That just doesn't work in a big lathe with a long head stock.

Daryle says the PM 1440 I use at work is a "cute little lathe." I think the manual machine he works on is a 60"--it looks to be 6+ feet long.

 

[Ksracer]

but they have zero issue with how I dial in--straight from just ahead of the throat to about 1/2" in front of the breech. That just doesn't work in a big lathe.

I think he was referring to holding the reamer, not the barrel.

Regardless, it's not a big deal to dial in that way on a larger lathe, you just have to hold the barrel from only the bree h end instead of using an outboard spider. My Kingston is 67" between centers and 10' long overall and I've used a "Viper Jig" a lot and currently use a true bore system. Either way works fine if the muzzle doesn't extend out the back.

 

[Carl S]

Lock down your tailstock put a dti into the hole you have just bored for your reamer.wind the tailstock see if the indicator moves.unlock the tailstock slide it up and down the bed and reindicate.remove your morse taper,reinsert it and indicate it again..see if there is any difference!!a block mounted in the tool post is the better option.your going need a real mint lathe for 100% repeatability with the rigid reamer in the tailstock.

 

[boltfluter]

No go for me with the tail stock and a Morse taper. To many things to stack tolerances with. Most lathes we use for chambering are just hobby lathes. Not even remotely like a Hardinge or a Monarch. Like going to Indy with your Chevy Nova! Good luck, your gonna need it.
Paul

 

[sdean]

This. ^^^^^^^^^

 

[INTJ]

I think he was referring to holding the reamer, not the barrel.

Regardless, it's not a big deal to dial in that way on a larger lathe, you just have to hold the barrel from only the bree h end instead of using an outboard spider. My Kingston is 67" between centers and 10' long overall and I've used a "Viper Jig" a lot and currently use a true bore system. Either way works fine if the muzzle doesn't extend out the back.

True, but my point was that what's works best for master machinists using a big lathe doesn't always translate well to self-taught guys using small lathes.

 

[Machinist John]

Once upon a time I saw a photo!!!! Using a torque wrench to tighten the tail stock spindle lock consistency.

Different torque settings would raise or lower the tailstock spindle. Or sideways depending on how the lock was made.



Think about this.


Solid reamer holders?? I have lots of them, both from the major manufacturers and some I have made.

This one I made from a MT adapter. Holds 7/16" shank chamber reamers.

But it is used with a tool room quality floating holder.

 

[tobnpr]

and if machined properly should be dead nuts to the specific machine.

Sure will.
And if there's any radial misalignment of your headstock, that is obviously transferred into the hole you just bored into the tooling block/holder using the headstock. Seems to me that screams potential "oversize hole".

For me (and my old 'Merican iron), I see no upside compared to indicating, drill/bore and a floating holder that'll allow the reamer to follow that hole. I'm all about trying different methods (and I have), but I need to see potential upside as a prerequisite and I just don't see it here. I'm of the "If it ain't broke, don't fix it" school.

 

[LVLAaron]

Sure will.
And if there's any radial misalignment of your headstock, that is obviously transferred into the hole you just bored into the tooling block/holder using the headstock. Seems to me that screams potential "oversize hole".

For me (and my old 'Merican iron), I see no upside compared to indicating, drill/bore and a floating holder that'll allow the reamer to follow that hole. I'm all about trying different methods (and I have), but I need to see potential upside as a prerequisite and I just don't see it here. I'm of the "If it ain't broke, don't fix it" school.

Well said, and that's where my thinking has been. It doesn't matter how big or small your machine is... the same problems exist.

 

[xr650rRider]

Seems like it worked pretty decent for the original subject.

0.359" first 3 shots on paper for a 7PRC.

 

[Sniperhandle]

Seems like it worked pretty decent for the original subject.

0.359" first 3 shots on paper for a 7PRC.

I watched both of his 7mm PRC videos and I will say he is honest, Because I would have had to go back to the drawing board with the groups he posted. Not bashing but if it doesn't shoot 1/2 of that or close to it, I'm not happy.

And as far as using a rigid holder like that, You better be darn sure everything is perfect.

 

[Bronsin]

As a machinist for most of my life, I have to ask one question about this method. What problem is it trying to solve? By the time you spend $700 on a Criterion boring head, a boring bar, and a shank to mount it in the chuck, then indicated the tailstock square and parallel and made sure it's travel is parallel to the chuck to make a straight hole, you could have just bought a floating reamer holder and been done with it all.

This method shows what can be done, and done right, it will work, but there are simpler ways of doing this without all of the pitfalls to precision it takes to make it happen. The second you loosen the tailstock you have to start all over. I have worked with a master machinist for 14 years, and he has a wooden box filled with all of his projects that are a monument to what can be done, not necessarily how it should be done. One of these is a ball bearing, with a .017 hole bored through it. How small of a hole did he need to get the boring bar in? How small was the boring bar and how long did it take to make it? What did he use to break through the hardened steel outer layer? I would have just sent that out to be EDM'd.

 

[ridgeway]

This is a whole lotta work to gain pretty much nothing in the end. I'm another in agreement that once the hole is bored in the tapered endmill holder, getting it to repeat is like trying to win the PowerBall. It will most likely be close enough that it will work no matter what. I've been using a JGS floating holder for years and it makes a true, tight round hole in the end.

 

[BoydAllen]

Question for the rigid guys. How many of you have verified that the axis of your tailstock quill is parallel to, much less coaxial with that of the headstock? It seems to me that if you do not have this condition, even if you are perfectly aligned at some point of extension that you will not be at another, or is my visualization faulty?

 

[LVLAaron]

What problem is it trying to solve?

Ever used a carbide chamber reamer?