Spider in steady fingers question..

S

skipkh

New member
Hi all!

Been toying with the idea of running a spider in the steady for chambering/threading and wanted to pass it by more intelligent minds than mine : )
I believe this has been done before, just not a ton of info on it.
I'm thinking of making a spider out of 12L14 around 2" OD and 1" long. It will be perfectly round on the OD with one end having 4 brass set screws and the other smooth. The fingers will obviously run on the smooth end. I'll ream a 1.5" hole through the center. The idea is to put it in the fingers of the steady with the chamber end of barrel through it. A 4-jaw will drive the muzzle end. Unless I am missing something I should be able to indicate the chamber for radial runout using the set screws in this spider, and indicate the axial with the 4 jaw. It's basically the same as using a spider on the backend of the spindle except in reverse - still there exists 2 adjustable points of contact. I think this would be useful for those of us that have lathes that do no have sufficient hole through spindle, or headstocks that are very long where we don't want to deal with barrel extensions. It would allow for more precise indication of the barrel in the steady setup vs just using centers, which as we all know is no guarantee the bore is running true.

Am I missing something here or is this a sound idea?

thanks for any advice!
 
IIRC - which is always questionable...

skipkh said:
Hi all!

Been toying with the idea of running a spider in the steady for chambering/threading and wanted to pass it by more intelligent minds than mine : )
I believe this has been done before, just not a ton of info on it.
I'm thinking of making a spider out of 12L14 around 2" OD and 1" long. It will be perfectly round on the OD with one end having 4 brass set screws and the other smooth. The fingers will obviously run on the smooth end. I'll ream a 1.5" hole through the center. The idea is to put it in the fingers of the steady with the chamber end of barrel through it. A 4-jaw will drive the muzzle end. Unless I am missing something I should be able to indicate the chamber for radial runout using the set screws in this spider, and indicate the axial with the 4 jaw. It's basically the same as using a spider on the backend of the spindle except in reverse - still there exists 2 adjustable points of contact. I think this would be useful for those of us that have lathes that do no have sufficient hole through spindle, or headstocks that are very long where we don't want to deal with barrel extensions. It would allow for more precise indication of the barrel in the steady setup vs just using centers, which as we all know is no guarantee the bore is running true.

Am I missing something here or is this a sound idea?

thanks for any advice!
Click to expand...

I think Steve Acker ("Gunsmith Machinist" from the Village Press Mags - Home Shop Machinist and Machinist's Workshop) did something very similar in a video they produced. Never tried it myself. Seems workable, in conjunction with wires or whatever to allow the chucked end to move axially without undue stress.

GsT
 
thanks for the lead! I'll try to hunt down the video.
Yep - I use 4g copper wire in the 4-jaw when I chamber in the headstock, so planning the same in this setup.
 
skipkh,

I've found that pivoting the barrel exactly on the leade of the proposed chamber throat is an incredible timesaver so may I suggest that whatever you make, that it have this capacity.
 
alinwa said:
skipkh,

I've found that pivoting the barrel exactly on the leade of the proposed chamber throat is an incredible timesaver so may I suggest that whatever you make, that it have this capacity.
Click to expand...


That's an excellent tip! I can place the set screws where the proposed leade would be in this design very conveniently. I can also see two pivot options..
1) put a slight crown on the race of the spider which would facilitate pivot.
2) Shape the ends of the set screws as a ball, which would also serve to facilitate pivot.

A few of the advantages of this design is it's lathe agnostic. With a spindle spider I have to sort out an attachment method for each machine. This solution would fit any steady rest.
Another advantage is as you mentioned. I can move the steady to wherever I need it relative to the chamber... something not so convenient when held in the chuck. The obvious concern is rigidity, however I think it is ok. I will test and see pretty quickly.
 
alinwa said:
skipkh,

I've found that pivoting the barrel exactly on the leade of the proposed chamber throat is an incredible timesaver so may I suggest that whatever you make, that it have this capacity.
Click to expand...

Al, you betcha! It's a massive time saver!! Yet i've almost never heard the "Internet" gunsmith gurus even mention it.
It's something i have always done when fitting barrels as it does indeed save a LOT of time dialing one in..

Cheers
Lee
 
So, how do you indicate the bore in the muzzle end that is in the 4 jaw. Maybe you're using the gordy method?
 
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How would one then get all three points to be running true each other. The muzzle, the area in front of the throat and the chamber. This has been my own approach and it came from Jackie Schmidt sharing his own personal method.
 
Butch Lambert said:
So, how do you indicate the bore in the breech end that is in the 4 jaw. Maybe you're using the gordy method?
Click to expand...

Hi Butch!

Glad you chimed in : )

Muzzle end goes in the 4-jaw. Breech end rides in the spider located in the fingers of the steady. Indicator rod (or DTI with long feeler) goes in the bore. set screws on spider in the steady are used to dial in the bore for runout. 4-jaw (with copper wire between jaws and muzzle end of barrel) are used to dial in the bore for axial alignment. Basically the roles of the spider and the chuck are reversed regarding what they adjust for vs the typical chamber through headstock method.
 
Louis.J said:
How would one then get all three points to be running true each other. The muzzle, the area in front of the throat and the chamber. This has been my own approach and it came from Jackie Schmidt sharing his own personal method.
Click to expand...

It's been my experience that this is not typically achievable. The bore isn't straight on most barrels. If you dial in the muzzle then the chamber end will be out and vice versa. In chambering, at least in my experience, I ignore the muzzle when setting up to chamber. Where the leade is going to be needs to have no runout - ie; in line with the center of the lathe. The chamber area of the barrel needs to have no axial runout. Those are the two areas of concern. See my reply to Butch as to how this is accomplished. Basically it's the same as a spider on the rear of the spindle but the roles of the chuck and the spider are reversed with respect to what aspect they adjust for.
 
yo skipkh..... I started a youtube channel just to illustrate my method of making perfectly aligned and perfectly identical chambers..... and to prove that I can unscrew a barrel chambered yrs prior and set 'er BACK in the lathe to the same index...blind...and included is my way of affixing/swiveling/driving/holding which I'm perty psyched about....... how I make my soft swiveling pads. Dunno if this applies to what you're doing but it is a slick way to grip tapered surfaces, I'd use this at least on the drive end if fear of marring is a thing.

Mfgr of holding stuff starts around 5.00 in the vid

https://www.youtube.com/watch?v=zzq_uLa0-NE
 
skipkh said:
It's been my experience that this is not typically achievable. The bore isn't straight on most barrels. If you dial in the muzzle then the chamber end will be out and vice versa. In chambering, at least in my experience, I ignore the muzzle when setting up to chamber. Where the leade is going to be needs to have no runout - ie; in line with the center of the lathe. The chamber area of the barrel needs to have no axial runout. Those are the two areas of concern. See my reply to Butch as to how this is accomplished. Basically it's the same as a spider on the rear of the spindle but the roles of the chuck and the spider are reversed with respect to what aspect they adjust for.
Click to expand...

Sorry, I messed up, but corrected it. You are using the gordy method.
Oh well.
 
This method of chambering is based on the premis that you can only get the ID of a barrel dead true in two spots. So, you establish those two spots, (the muzzle and where the throat will be established), and single point bore the third spot, i.e. the chamber, dead true with these. You don't worry about everything in between.
 
Louis.J said:
This method of chambering is based on the premis that you can only get the ID of a barrel dead true in two spots. So, you establish those two spots, (the muzzle and where the throat will be established), and single point bore the third spot, i.e. the chamber, dead true with these. You don't worry about everything in between.
Click to expand...

Louis. you've described the standard method of chambering around here..... ie to align muzzle and throat. 99.9% of all accuracy-minded and Bench Rest Gunsmiths do it this way.

"Gordying" is completely different.

On that subject, much as I distrust 'straight' barrels I've had a slew of them lately! 8 out of 12 have shown less than a thou of runout. The way I do them I do all my setup work inboard at the 4-jaw ......then last thing, just as I'm locking down the outboard or spider end I slip a tight-fitting reamer bushing up past the lapping bell (I've a machined brass hook to get it back out) to find the runout.
 
Al,
I've seen a custom built steady using a high grade bearing instead of fingers with a spider built in. I seem to recall it was used for shotgun choke work. Made sense to me at the time. Would be fine for barrel work.
 
I have seen a couple steadies as Dave has mentioned. It is probably a minor measurement, but how close can the muzzle be in the 4 jaw? Are you going to make a cleanup on the muzzle OD before putting it in the 4 jaw?
 
Butch Lambert said:
I have seen a couple steadies as Dave has mentioned. It is probably a minor measurement, but how close can the muzzle be in the 4 jaw? Are you going to make a cleanup on the muzzle OD before putting it in the 4 jaw?
Click to expand...
I think I'd have to crown it first, find bore center line and turn the outside to match to give me an indexing point. Then of course I would jack it out wild because I don't care where the muzzle ends up doing it my way LOL. I would only do it to know where the run out is directionally at the muzzle
 
alinwa said:
I think I'd have to crown it first, find bore center line and turn the outside to match to give me an indexing point. Then of course I would jack it out wild because I don't care where the muzzle ends up doing it my way LOL. I would only do it to know where the run out is directionally at the muzzle
Click to expand...

The "Gordy" method. I've never been warm and fuzzy doing it that way Al.
 
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alinwa said:
I think I'd have to crown it first, find bore center line and turn the outside to match to give me an indexing point. Then of course I would jack it out wild because I don't care where the muzzle ends up doing it my way LOL. I would only do it to know where the run out is directionally at the muzzle
Click to expand...

AL,
I'd use a spider instead of the 4 jaw. Easier to adjust with the screws vs the chuck jaws.
 
Butch , I know.... you've made that clear :)

Dave, I've never understood this, to me they're identical to adjust (I do have two mini keys)
 
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