Lyman M die problem......

[3006guns]

I have a Lyman M die that I use for opening up 7.7 Jap and .303 Brit. cases for cast boolits. So far it's worked admirably, but on my last batch of cases it started suddenly flaring the case mouths wildly. I changed adjustments several times before it occurred to me to take it apart. I found the sizing mandrel had unscrewed a turn or two, so I tightened it down. Problem solved, right? Not so.....within another 20 cases the over-flaring started again and, sure enough, the mandrel was loose.

I'm sure not going to crank that thing down with pliers and ruin the ground finish, so I was thinking of something like nail polish on the threads to prevent movement. Thread lockers, like LocTite are a no no as they require heat to break the bond if the mandrel needs to be changed. A nail polish bond can be broken with the fingers.

Another idea might be the world's smallest lock washer, as used on model airplanes.

Any ideas out there to keep this thing tight?

[farmerjim]

I have had the same problem. Use blue loctite in the threads.

[GrayTech]

Wrap a piece of leather around the mandrel, grab with pliers and crank it down. The low strength loctite never hardens fully, it stays soft and just creates a lot of drag on the threads.

[Maven]

Blue Loctite solved my M-die problems as well.

[ReloaderFred]

I also used the blue Loc-Tite to solve this problem.

Hope this helps.

Fred

[308Jeff]

The first thing I do when I buy a new M Die is apply blue Loctite to the threads.

[3006guns]

Thanks guys.............blue Loc-Tite it is. I'm only familiar with the other grades, which can permanently lock the threads.

[Smoke4320]

Blue will break loose with a simple wrench (or in this case leather and pliers) .. no heat needed

[mdi]

Actually there are other thread lockers available if you don't have Loc-Tite on hand. You can dab some nail polish on the threads which will hold or super glue, epoxy etc. Just clean the threads with brake clean (or acetone, lacquer thinner, any solvent that will leave no residue) before application. You can try just cleaning the threads and tightening the mandrel. Clean, oil free threads hold much better than any with oil on them...

[Motor]

You can use a little Teflon pipe tape as well I believe.

There is no need to fear most Loc-Tite products. Most normal ones will let go if heated. It's actually amazing how many different ones they make.

Motor

[dragon813gt]

Blue requires no heat to break free. It's the most versatile one they offer.

[Kestrel4k]

Clear nail polish is $1 at the local dollar store; have been using it for years & it performs perfectly.

[KenT7021]

I use VC-3 thread locker.It functions like a self locking nut and be disassembled and reassembled without loosing the locking ability.

[gwpercle]

Wrap a piece of leather around the mandrel, grab with pliers and crank it down. The low strength loctite never hardens fully, it stays soft and just creates a lot of drag on the threads.

And/or pad the pliers teeth, leather , duct tape, just use anything to keep from marring the metal. Once it's good and tight it will stay tight. The nail polish, just a little will help, with the padded pliers and some elbow grease , that will stop the unscrewing.
I fixed a set of old slip joint pliers buy grinding the sharp teeth off and gluing leather to the jaws and keep it next to press for tightening and loosening die parts for adjustments. Works well.
Gary

[brassrat]

I use tiny O-rings and tighten well