Sinclair Neck Turning Mandrel Question

[slas]

Is the Sinclair mandrel that's used for regular expansion the same size as the Sinclair neck turning expander mandrel they send you for use with the neck turning tool?

So, the question is, if you have all Sinclair mandrels already for neck expansion do you have to buy another set for neck turning? Hoping I can just buy the neck turning mandrel and use the expansion mandrels I've already bought for the initial step.

 

[Mikecr]

Their turning mandrel is 2thou under cal. Their complement expander mandrel is 1thou under cal.
That's all they have

 

[slas]

Their turning mandrel is 2thou under cal. Their complement expander mandrel is 1thou under cal.
That's all they have

So their regular expander mandrel is the same size as comes with the kit, if I understand you correctly.

 

[QuietTexan]

Yup. There are several options for actual specified sized mandrels: K+M, 21st Century, SAC, and Porter Precision.

 

[slas]

I'm trying to control cost and buy the minimum I will need to start. So, if I already have Sinclair mandrels, that are the same size as the ones that come with the kit for turning necks, that will save me on that initial cost. I can pick up more as I go, but don't have several hundred to spend at this time. Though it might be a while since I noticed Sinclair is out of stock on their NT-4000's.

 

[Mikecr]

So their regular expander mandrel is the same size as comes with the kit, if I understand you correctly.

Yes, that's right

 

[QuietTexan]

I'm trying to control cost and buy the minimum I will need to start. So, if I already have Sinclair mandrels, that are the same size as the ones that come with the kit for turning necks, that will save me on that initial cost. I can pick up more as I go, but don't have several hundred to spend at this time. Though it might be a while since I noticed Sinclair is out of stock on their NT-4000's.

Valid point. Have you considered K+M for turning tools instead of Sinclair's?

The K+M turning body is less expensive than Sinclair's fancy model, but that's a benefit to me. The K+M is cheap enough that you can keep one per chamber instead of adjusting constantly. I have one that's set to match a reamer, and it will literally never move again because it's set to cut the final turn to match chambers cut with that reamer. I don't need the dialing in feature of the Sinclair's because I don't want to adjust the cutter constantly. I want to either turn the entire batch of lot matched brass I just bought (meaning I won't ever need that exact setting again), or dedicate a turning body to a reamer.

K+M also has a good selection of cutter angles to better match shoulders, which is a pretty significant concern IMO.

I was about to buy Sinclair's several times, but I'm glad I didn't because I've received much more benefit from the low cost bodies than I would have from the more precise NT-4000.

Nothing against Sinclair's, I have plenty of their tools (including mandrels actually), but there are other options.

 

[slas]

Valid point. Have you considered K+M for turning tools instead of Sinclair's?

The K+M turning body is less expensive than Sinclair's fancy model, but that's a benefit to me. The K+M is cheap enough that you can keep one per chamber instead of adjusting constantly. I have one that's set to match a reamer, and it will literally never move again because it's set to cut the final turn to match chambers cut with that reamer. I don't need the dialing in feature of the Sinclair's because I don't want to adjust the cutter constantly. I want to either turn the entire batch of lot matched brass I just bought (meaning I won't ever need that exact setting again), or dedicate a turning body to a reamer.

K+M also has a good selection of cutter angles to better match shoulders, which is a pretty significant concern IMO.

I was about to buy Sinclair's several times, but I'm glad I didn't because I've received much more benefit from the low cost bodies than I would have from the more precise NT-4000.

Nothing against Sinclair's, I have plenty of their tools (including mandrels actually), but there are other options.

Did you buy K&M expander mandrels or use your Sinclair?

 

[QuietTexan]

I used either a K+M expanding mandrel, a Sinclair's expanding mandrel, or an LE Wilson "new" mandrel depending on caliber. The K+M and Sinclair's measure -0.002" and LE Wilson's measures -0.0015", all of them work fine for the -0.001" K+M turning arbor so far. I want to say I have TiN and carbide expanders from Sinclair's, but I'd have to check to be sure.

There's nothing about any given turning system that requires you use their exact expander. If a mandrel measures out correctly, doesn't matter where it came from, just that it opens the neck enough.

 

[Mikecr]

I think what I like the best about Sinclair's latest mandrel die is that it allows mandrels to float for truer expansion.
This also provided me with an ability to measure pre-seating forces with a load cell installed in the mandrel die cap, which the floating mandrels press against.
The Sinclair system has become a standard I guess, as other folks are offering compatible mandrels for it.
That's a good thing.

I don't know about the other systems old & new, but be careful about any that fix mandrels as rigid.
Mandrel expansion is not for straightening necks,, that's what fire forming does.
But floating mandrels do not pull necks out of straight/centered, as die buttons sometimes do, or rigid mandrels in a poor alignment could.
Hope that makes sense

 

[QuietTexan]

I think what I like the best about Sinclair's latest mandrel die is that it allows mandrels to float for truer expansion.
This also provided me with an ability to measure pre-seating forces with a load cell installed in the mandrel die cap, which the floating mandrels press against.

What does that setup look like? I'd be interested in a way to measure pre-seating force also.

The Sinclair system has become a standard I guess, as other folks are offering compatible mandrels for it. don't know about the other systems old & new, but be careful about any that fix mandrels as rigid.

Yes, the 21st Century mandrels are floating in the similar way to how Sinclair's are. LE Wilson, K+M, Porter, and SAC are not - LE Wilson screws on, SAC and Porter use collets around a mandrel that I would assume give some limited flex, and K+M I honestly can't recall off the top of my head. The SAC mandrels are also designed to be used in conjunction with their sizing die, so the design might be a tradeoff to be functional with the neck inside a bushing rather than focusing on using separately.

Mandrel expansion is not for straightening necks,, that's what fire forming does. but floating mandrels do not pull necks out of straight/centered, as die buttons sometimes do, or rigid mandrels in a poor alignment could.
Hope that makes sense

I agree and think you're essentially saying that while a floating mandrel does not correct poor concentricity, it also doesn't induce any.

 

[Mikecr]

What does that setup look like? I'd be interested in a way to measure pre-seating force also.

What it looks like is junk thrown together from parts bins in the garage..
But it works just fine. A FlexiForce sensor and basic meter drive circuit, 9v batt.

 

[Mikecr]

I agree and think you're essentially saying that while a floating mandrel does not correct poor concentricity, it also doesn't induce any.

One thing mandrels do for you is push thickness variance outward -away from seating bullets. This, reducing loaded runout.
A floating mandrel cannot add to loaded runout, nor offset or skew necks. So there is no downside to it.
As to concentricity: it means nothing good to me. I want straight ammo, reading low in TIR.

 

[SteveBurton]

I didn't know that some mandrel holders allowed them to float so I made my own. It's just a standard PMA Tool holder but I replaced the set screw with a socket head screw and a lock nut similar to the Redding S type dies. Just lock it down so there is a couple thou play. I find it works pretty well but now I'm interested in how the 21st Century tool works. I like their stuff anyway.