New Brass prep service offering.

[jackieschmidt]

Very nice!

Question: Is the case head loose in the tailstock holder so it can spin freely? Doesn't look like a live center is why I ask.

Here is a video that shows the process with more detail
this is me turning necks on our Monarch EE at my business. As you can see, the shell holder has enough clearance to allow the case head to spin freely.

The downside to this is every time you decide to turn necks, you have to machine a new mandrel if you want them perfect. The mandrel is machined to bullet diameter.

this will not turn necks any “better” than a properly used hand neck turning tool. It’s just a heck of a lot faster. The little mist cooler keeps the mandrel cool.

I now do my cases on my 14” Turnmaster lathe at my house.

 

[Chris Edmondson]

Thanks @jackieschmidt, that's really helpful to watch. I was wondering if you went in from mouth to shoulder, then a spring pass back out, that appears to be the case. I'm using a PMA shell holder in my tailstock which is a bit of a grind, sure like to know what mount you used for your setup?

With my Super Premium Offshore lathe , I can achieve slightly better mandrel runout chucking a .264 pin gage in an ER25 straight-shank collet, then chucking that assembly in my 4-jaw independent, ugly as sin, but it gets the job done.

 

[jackieschmidt]

Thanks @jackieschmidt, that's really helpful to watch. I was wondering if you went in from mouth to shoulder, then a spring pass back out, that appears to be the case. I'm using a PMA shell holder in my tailstock which is a bit of a grind, sure like to know what mount you used for your setup?

With my Super Premium Offshore lathe , I can achieve slightly better mandrel runout chucking a .264 pin gage in an ER25 straight-shank collet, then chucking that assembly in my 4-jaw independent, ugly as sin, but it gets the job done.

View attachment 1423696

Correct, I take a “rough cut” by hand, just kiss the neck shoulder junction, then power feed it back out To finish it.

I like your set up. If it works, that’s what counts.

 

[Carden260]

Jason, Agreed, I've noticed that most forms of brushing and various lubes do help with seating smoothness, I've confirmed it with my homegrown seating force gage.

Here's a picture showing my inside turning best-effort; the brass is on the left, the roughness 63 Ra comparator is on the right. This was captured with a Teslong borescope. 63 Ra is described thusly: "Good machine roughness/finish with its production under controlled conditions. It also involves fine feeds and relatively high speeds."

View attachment 1423548

This next picture shows a piece of virgin Lapua 6.5 Creedmoor brass as seen with the borescope. It's darn near a mirror finish..

View attachment 1423554


The picture below shows a borescope view of the roughness comparator's 16 Ra turn, that's a fine as it gets for this tool. 16 Ra is considered: "High-quality surface are often produced using emery buffing, lapping, or coarse honing. These finishes are therefore great options where smoothness is of high importance."

View attachment 1423557


For me, I don't see how anything I do the inside of my necks is going to improve the original surface finish. Being a stubborn sort, that didn't stop me from trying, lol.

If I ever decide to revisit inside turning, I'll either hire the OP to do it for me, or sell my wife's dog in order to buy my own AutoDOD .

Its not the finish I try to achieve by turning the inside and the outside. its the complete concentricity of the neck so neck tension is uniform. I have seen ZERO POI change from smooth to rough finish. I have seen zero POI change on force variances in seating pressures. I sold my amp press, and my 21st Century force gauge.
Personally i think people waist too much time chasing shit that doesnt matter. People should spend more time practicing in the wind then prepping brass. Me included. just my .02. My reason for owning an AutoDod is I prep 300-400 case a year would take too long with other conventional means

 

[Dusty Stevens]

Thanks @jackieschmidt, that's really helpful to watch. I was wondering if you went in from mouth to shoulder, then a spring pass back out, that appears to be the case. I'm using a PMA shell holder in my tailstock which is a bit of a grind, sure like to know what mount you used for your setup?

With my Super Premium Offshore lathe , I can achieve slightly better mandrel runout chucking a .264 pin gage in an ER25 straight-shank collet, then chucking that assembly in my 4-jaw independent, ugly as sin, but it gets the job done.

View attachment 1423696

The way jackie does it and is able to hold the kind of concentricity he does is he turns the mandrel in the lathe then turns the brass. Using the setup you have there youll never be able to get the sub tenth runout you need to turn necks. All you gotta do is put an oversized pin in there and cut it to size as you get ready to turn. It doesnt have to be a hardened pin

 

[Chris Edmondson]

The way jackie does it and is able to hold the kind of concentricity he does is he turns the mandrel in the lathe then turns the brass. Using the setup you have there youll never be able to get the sub tenth runout you need to turn necks. All you gotta do is put an oversized pin in there and cut it to size as you get ready to turn. It doesnt have to be a hardened pin

I agree that turning the mandrel in-place is likely to result in less runout than chucking a gage pin, especially in the context of a real lathe. I've tried it it both ways with my wannabe; it's a tie for the most part, but the pictured setup wins by a tenth. Regardless, the setup reliably and repeatedly holds < 0.0003 TIR over the entire length of the mandrel's bearing surface, that's as good as it gets with what I got .

 

[dcali]

Its not the finish I try to achieve by turning the inside and the outside. its the complete concentricity of the neck so neck tension is uniform. I have seen ZERO POI change from smooth to rough finish. I have seen zero POI change on force variances in seating pressures. I sold my amp press, and my 21st Century force gauge.
Personally i think people waist too much time chasing shit that doesnt matter. People should spend more time practicing in the wind then prepping brass. Me included. just my .02. My reason for owning an AutoDod is I prep 300-400 case a year would take too long with other conventional means

I'm not trying to be a smartass, but how does an autodod increase concentricity? When I turn cases on my hand held sinclair, they come out more concentric than I am able to measure with a tube mic. There's never any measurable variation from one side of the neck to the other.

In my experience good brass (Lapua, etc) tends to only be a few tenths off even before you turn it. You might get one case in a box that's off .001". (I measured a boatload of cases at multiple points around the neck once just to see).

 

[Chris Edmondson]

Its not the finish I try to achieve by turning the inside and the outside. its the complete concentricity of the neck so neck tension is uniform. I have seen ZERO POI change from smooth to rough finish. I have seen zero POI change on force variances in seating pressures.

I agree that uniform roughness is likely no worse than unform smoothness. The challenge with a single-point cutting tool, like a boring bar, is having sufficient metal to remove in order to achieve the cutter's specified potential. For example, the Sandvik Coromant solid carbide boring bar I use recommends a minimum 0.004" depth-of-cut (DOC) to meet spec; the 6.5 Creedmoor Lapua brass I favor has an average wall thickness of 0.014", my rifle likes 0.0125", that means I need to turn off 0.0015". If I'm going to turn the inside and the outside, I'm limited to taking just 0.00075" off each side. I tried this with unacceptable results, then I tried taking 0.001" of the inside and 0.0005" off the outside, that was as good as I could get it. Being well outside the specified DOC of the cutting tool is no doubt why I couldn't make it work, now throw in a couple tenths of starting neck runout, I had no confidence in the uniformity of the roughness, regardless of whether I could settle for the roughness at any observation point. The AutoDOD guys are Rockstars, they cracked the code .