BUBBA needs a winter project.

cet

cet

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Howdy folks,

Before I start my question, I should let you know that phrases like "reinventing the wheel"
and "putting lipstick on a pig" are not in my dictionary, however, the definition of BUBBA is !!

I happen to have an old Savage stailess barrel with a large shank, I happen to also have a new Axis with the smaller shank, they both happen to be in the same caliber.

Well.......Bubba's thinking what most intelligent people would not, install the stainless Savage barrel on the Axis.

Bubba also happens to own a Chinese mill/lathe combination, along with all the Chinese tools necessary to
do the job, quality and/or precision as well as machining experience were NOT included with the purchase.

My plan is to reduce the diameter of the large shank barrel to match the largest diameter of the small shank barrel and re-thread.
I do have a thread pitch gauge and it shows 20 TPI on the AXIS barrel, however the diameter is a bit of a mystery, I would like to use a die to make the threads and need the exact diameter, anyone know?
I measure 1.050" which is very close to 1"-3/64 th.

My next question is the bore of the Axis barrel, is it - normal - for the bore to be drilled off center in the barrel ? By that I mean the bore is NOT dead center mid way on the barrel, it IS centered at both ends.

Anyways, Bubba will be Bubba and try it during the winter, yes, I have safety glasses.

Any recomendations would be very much appreciated.

CET
 
I'd sugggest to located some larger sized round stock and learn how to turn down and hit a specific diameter, then learn to thread.
Threading isnt that hard after you get the hang of it and do it a few times.
 
Klebelenator said:
Good luck. Sounds like you're ready for the challenge.
Click to expand...

Yes, I am, I bought a leather apron, safety glasses, heavy leather gloves, ear protection, a cup for my balls (junior size), and have 911 on speed dial.

To me, this is like shooting that very first reload you made, close your eyes and hope for the best.
The only materials I've machined (if you can all it that) so far is plastics/composites/wood and some aluminum.
Real machinists should get a good hardy laugh at this, but please, if you see anything obviously wrong in the pic let me know.
The barrel is diled in to within 2 thou, trying some different shims to bring it closer.
barrel 011.jpg
 

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Leather gloves and rotating machinery don't mix. I'd also be leary of any clothing that could not be readily ripped away from my body.
 
looch said:
Leather gloves and rotating machinery don't mix. I'd also be leary of any clothing that could not be readily ripped away from my body.
Click to expand...

Yup, agree, I was just laughing at myself. The wife suggested a complete body condom.......go figure.

"If you can't laugh at yourself, you should not laugh at others........." my mother's favorite.
 
Here is how I would approach the job:
I'd make sure that the lathe is set for the correct number of threads.
Set the compound at 29 1/2 - 30 degrees.
Then I would adjust the tool to pick up the existing threads.
I would then start making light cuts until the receiver will screw onto the shank - or until the barrel nut will fit.

It is not unusual at all for the bore to be off-centre in the barrel. Can happen with almost any make.

It would be a really good idea to practice cutting threads on some scrap, before you go to work on the barrel.
 
Savage Axis use the regular small-shank thread on their barrel, I am sure 2 minutes on Google will get you the correct size. While you are at it, you could (if you feel like it) get rid of the barrel nut and make a shoulder with a regular recoil lug. If you are re-using the Axis stock it will not work, if you are making a new stock go for it.

Good luck, should be a fun project
 
ronnie01 said:
You need a 4 jaw chuck.

R
Click to expand...

Thanks everyone for the hints.

Yes, I need a 4 chuck head. I cannot believe how far off that factory barrel is.
Depending where on the barrel I measure, moving only my gauge, high and low spots on the existing diameter
change at rondom. It is not bent, as that should give me high spots at the same radial position everytime.
It's more like an "s" shape.
The deeper I dig, the deeper I get.

I might just do as Tiriaq suggested, forget about the barrel, start cutting the existing threads deeper until
the nut fits. The barrel shot fine before I retired it, maybe I should not screw with the taper.

Will a shoulder in front of the nut, on the barrel side (about 65 thou) cause any problems?
 
From one "amateur" to another, and for the life of me don't let me dampen your enthusiasm for venturing forth into this part of the sport. Just want to pass on some experiences I've had with similar set-ups. My first machine wasn't the same make as your but very similar in design. As you have already stated, working wood, plastic & alum. was a breeze...then I added steel to the equation and everything had to slow down to an absolute crawl...both RPM wise & cut size.
The problem is the rigidity of the machine. Notice the height of the tailstock from the bed & cutter from carriage slide, the length in there allows for flexing of the work away from the cutter or cutter from the work even with a mild steel work piece (this necessitates very very light cuts or the cutter will "dig in" when least expected or wanted) and you are working with stainless. A "digging in" cutter can cause severe damage to your machine before you get it stopped. The flexing will also cause uneven cuts over the distance the cutter travels resulting in different diamters from one end of a cut to the other.
I never tried stainless in my combo outfit but have since tried it in my 1440 machine and have found it very tough to machine properly. I know lots of trained machinist turn stainless every day with fantastic results but me, as an amateur, haven't found the technic yet.

Hopefully somebody will chime in with some tips on stainless for both of us
 
If your bore is that far off center, take off your chuck, put on your face plate and install a center into the spindle's bore. Slip a dog leg over the barrel before hand with the paw facing the proper direction so it can be captured in one of the face plate slots. Install the barrel between the spindle center and the tail stock center.

Now very important. You will want to establish your dog leg to remain tightly in place with the paw in a slot. This is done by means of a square headed set screw on the arbor of the dog leg. I usually wrap a piece of heavy brass shim sleeve around the barrel at this point.

If you decide you want the barrel profile to match the axis of the bore, you should also install a follower rest to your lathe saddle if you are going to attempt this.

With your mill/lathe, the only way you can cut the taper is to offset the tail stock by the amount you want to take off to achieve this. Again, take very small cuts and use lots of lubricant. Do not get impatient. You do not want to heat up the barrel while doing this job. I have seen more than one barrel that has a definite bow in it because the smith/machinist became impatient.

This will allow your threads to be cut true to the axis of the bore without it looking like it is pointing off to the wrong direction.

Once this is done, go ahead and cut a shoulder to establish against the receiver by turning the portion of the shank you are going to thread down to the root diameter. Go ahead and cut the threads as tiriaq suggests.

After the threads are cut to perfection, take the barrel out from between the centers and put the three jaw chuck back onto the lathe.

This is where you need a spider on the outlet side of the spindle. Most Chinese lathes come with one, not all. This is used to dial in both sides of the barrel. Because the outside profile is very close to square to the bore's axis a dial gauge can be installed on each end to measure run out. In your case, you will need to shim to get center as very few lathes have three jaw chucks that will clamp on dead center. I have never seen one personally. I have seen lots of attempts at correcting this, the most common is to drill the jaw faces. This leads to all sorts of problems because the jaws have to be turned tightly in place and when drilled, become loose and you lose the center again. Not only that, you end up with spherical faces that will only fit the profile of the drill.
 
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Fingers 284........hear you, I had problems with chattering. From everything I've read, you are right, my machine is the equivalent of a large piece of Jello. I had to center my cutting tool properly and SLOW everything down, as you say, small cuts and lots of lubrication. That seems to fix the chattering (that was fixed today, after your post, thank you) .

Bearhunter..........looking for some of the terms you used on the web right now, I'm just a wee bit over my head on this.
Once I get control of, and understand what I have so far, I'm going to read and study your post.
Please believe me when I say "Thank You".

CET
 
As above:

I have a quick question for the machinists out there:

I'm trying to learn how to cut 20 TPI threads on a cheap mill/drill.
I have my tool cut, my gears changed, and have cut some practise threads in aluminum stock.
Everything looks good, the only problem I still have is lack of position indicator on my carriage.

I have tried some of the tricks shown on you tube, marking all starting positions with a marker and
it works, but does not seem to be as reliable as I would like.

One method I have tried that seems to work is reverse/forward on the drive motor, without moving anything else.
Is it safe to stop the cutting operation with the tool still cutting material?
While practising, I cut a relief groove at the end of the threads, and tried my best to stop there everytime, but it's difficult.
The threads I've cut using this method are perfect, but is it safe? I will NOT have a relief groove when cutting my stainless barrel.

Any suggestions would be appreciated.

CET.........AKA an accident waiting to happen.
 
cet said:
As above:

I have a quick question for the machinists out there:

I'm trying to learn how to cut 20 TPI threads on a cheap mill/drill.
I have my tool cut, my gears changed, and have cut some practise threads in aluminum stock.
Everything looks good, the only problem I still have is lack of position indicator on my carriage.

I have tried some of the tricks shown on you tube, marking all starting positions with a marker and
it works, but does not seem to be as reliable as I would like.

One method I have tried that seems to work is reverse/forward on the drive motor, without moving anything else.
Is it safe to stop the cutting operation with the tool still cutting material?
While practising, I cut a relief groove at the end of the threads, and tried my best to stop there everytime, but it's difficult.
The threads I've cut using this method are perfect, but is it safe? I will NOT have a relief groove when cutting my stainless barrel.

Any suggestions would be appreciated.

CET.........AKA an accident waiting to happen.
Click to expand...

Without a thread dial indicator I think you are best served by the forward-reverse method. I have "uncoupled" the drive during threading(by accident most of the time) in my lathe and re-setting, even to a close tolerance can take much time.

As for treading without a clearance grove can be overcome. I have had to "extend" threads a turn or two when re-chambering a barrel and what I did will probably work for you as well. What I did was install a long,heavy handle on the outboard end of the headstock shaft and not use the machine power at all...just turn by hand the turn or two required and then back up by hand as well without disengaging the hook-up then advance cutter & repeat. Everything is done slow (no chance of an under-power jam-up at the end of the thread) but accurately.

Not something a commercial shop would probably use but for you and I time spent isn't always an issue. You are doing a long thread so will take considerable more effort than my one or two threads but still a viable option for a "no clearance groove" thread.
 
fingers284 said:
Without a thread dial indicator I think you are best served by the forward-reverse method. I have "uncoupled" the drive during threading(by accident most of the time) in my lathe and re-setting, even to a close tolerance can take much time.

As for treading without a clearance grove can be overcome. I have had to "extend" threads a turn or two when re-chambering a barrel and what I did will probably work for you as well. What I did was install a long,heavy handle on the outboard end of the headstock shaft and not use the machine power at all...just turn by hand the turn or two required and then back up by hand as well without disengaging the hook-up then advance cutter & repeat. Everything is done slow (no chance of an under-power jam-up at the end of the thread) but accurately.

Not something a commercial shop would probably use but for you and I time spent isn't always an issue. You are doing a long thread so will take considerable more effort than my one or two threads but still a viable option for a "no clearance groove" thread.
Click to expand...

That was the answer, took forever, have blisters on my palms, but the threads are cut and seem perfect.
The nut threads on nice and snug.

No broken tools, all fingers in place, it's a good day....AND I saved $0.01 worth of electricity !!.
(spent $10.00 on medication for the blisters)

Thanks fingers284.
 
Glad to be of some help to a fellow hobby machinist. We soon learn that it's cheaper to learn from someone else's experience/mistakes than spend exorbitant amounts of money on the "right tool"....sometimes....I, for sure, have as many machine mods/jigs in my shop that didn't work "as dreamed" as the one that did work.

Good luck with the rest of your project, let us know the results. If you need to run a finish reamer in your barrel to set headspace, I can give you a tip on building a floating reamer mount that works for about $15.
 
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