Stainless expanding mandrel polishing?

[TrxR]

Anyone here polish their stainless expander mandrel? If so what do you use to polish it?

Thanks

 

[creedfan]

flitz

 

[Dusty Stevens]

A brushed finish will be smoother than a polished one

 

[ridgeway]

Stainless isn't a good material for a mandrel, IMO.

 

[BoydAllen]

I would bet that these perform very well.
http://www.xxicsi.com/arbors-and-mandrels.html

 

[hoz53]

What would you recommend?

people have used carbide mandrals in the past. kind of expensive though. these coated ones from 21st century boyd points out look reasonable priced and would be worth a try imo. Oh and if not for this covid Id drive out for a visit.

 

[ridgeway]

What would you recommend?

Carbide or hardened carbon steel. Coatings on stainless are good. Melonited stainless would be top notch as well...

 

[Edd]

Anyone here polish their stainless expander mandrel? If so what do you use to polish it?

Thanks

I would use 3M 3000 grit Trizact.

 

[Varmint56]

I Make my mandrels out of 17-4 stainless in a h900 condition. Can be bought from Mc Master Carr. Makes an excellent mandrel & polishes

Up with almost any of your favorite methods! I just use 600 grit paper.

 

[carlsbad]

Coincidentally, not 2 hours ago I made a mandrel out of 01 tool steel. I polished it with decreasing size grit sandpaper to a mirror finish. It was exactly the size I wanted. However, it started accumulating brass on the surface after 50 necks. I went back to carbide, even though it isn't exactly the size I want. Anybody know where you can buy a .284 carbide expander? .2835?

 

[bozo699]

I would bet that these perform very well.
http://www.xxicsi.com/arbors-and-mandrels.html

They work great!...
Wayne

 

[sunnyfisher]

I tried that and it doesn't take much to reduce the diameter to useless.
Throw it away and buy a carbide expander mandrel, its well worth the price.

 

[D-4297]

You can polish a stainless mandrel using Jewelers "Red" rouge , mixed with a drop or two of plain old olive oil . and a cotton ball or even a clean patch . It will polish up to a mirror finish , and possibly remove a tenth or two . Patience is the most important ingredient in doing this . All of the pores in the metal fill with brass particles as they are being used , and polishing will clean out the pores , and make the surface smoother , too .

 

[MikeMcCasland]

Have it nitrided.

 

[ridgeway]

Coincidentally, not 2 hours ago I made a mandrel out of 01 tool steel. I polished it with decreasing size grit sandpaper to a mirror finish. It was exactly the size I wanted. However, it started accumulating brass on the surface after 50 necks. I went back to carbide, even though it isn't exactly the size I want. Anybody know where you can buy a .284 carbide expander? .2835?

Harden it and draw it back some.

 

[memilanuk]

A while back, I (and others) had found that the Lyman 'M' die expander made a pretty handy (and cheap!) expander mandrel. Just back it out enough so that you don't hit the flair portion, and voila! Works like a champ.

Except... previously, I'd had a fair bit of experience expanding .308 brass for neck turning. For whatever reason, the K&M expander mandrel tends to really load up with brass from the squeaky clean insides of the neck, and it absolutely did show up as variation in neck expansion. Spent a fair amount of time/effort getting that build-up off of there, only to have it come back again later. Had to get fairly liberal with the neck lube to prevent that.

Later, when I started using the Lyman M die expander... I was still cleaning cases down to bare metal using wet tumbling. Guess what? Bare necks, on that polished steel mandrel... yup, brass buildup, fairly quickly. Cleaned it up, polished it, got into a regular 'process' doing that. Then I started noticing my load was shooting poorly, seemingly for no reason. And that my seating force was getting noticeably higher. Huh, wonder if those are related... Oh, look at that: my expander is now closer to .305" than .306". No way in hell was I going to inside neck lube each and every case, every loading. Went back to a carbide .306 expander mandrel, and the problem 'went away'. It also probably would have went away when I went away from wet tumbling and leaving some carbon in the necks.

So... if you want to use regular stainless steel mandrels, have a ball.

 

[ronemus]

The expander should have a matte finish rather than a mirror polish; the polished mandrel will have much higher friction and as others have noted it will pick up brass deposits. I use Imperial Die Wax in the necks, applied with a cotton swab (I do it while watching TV); however, it might be easier to apply it to the mandrel - I may try that sometime.

 

[Lucky6547]

http://www.pmatool.com/custom-carbide-mandrel/

 

[searcher]

You can polish a stainless mandrel using Jewelers "Red" rouge

This on a moto tool buffer head

 

[D-4297]

I put mine in a collet on a Hardinge lathe , and did it with a piece of cotton ball , rouge , turned into a syrupy paste .Light hand pressure and it took about 15 minutes or so . Mirror finish , and reduced the diameter by .00015 ....And yes . I have the tools to measure that .