Another Lyman #450 Issue: Sizing Die Retainer Nut Size

[Maven]

Does anyone know the pitch and thread of the Lyman Sizing Die Retaining Nut (part #16 in Lyman's diagram in a previous thread)? I may have stripped the threads on the main casting and would like to purchase a die to rethread it. Lyman is asking $120 + S & H for a new body, which is ridiculous. Thanks in advance for your help!

[theperfessor]

I'll check it when I get off work later. I know a Lyman nut is 7/8" across the flats and RCBS uses a 15/16" nut. If your press truly has a stripped thread it might be possible to bore and thread it to take an RCBS nut instead.

[Maven]

Thanks for that, Keith! I don't think those very fine threads are stripped, but filled with lube, which I've been trying to remove. However, it wouldn't hurt to use a tap to recut or chase them, assuming one with those (Lyman's) dimensions exists. Btw, you're correct about the coarse threads on the RCBS Lub-A-Matics and the diameter of the die retaining nut. However, the diameter on the LAM I nut is different than on LAM II. I'll have to measure to determine which is which. Needless to say, rethreading to a larger diameter is an option I hadn't yet considered. Thanks!

[theperfessor]

The dimensions of the threads on the nut from my Lyman 450 is an OD of 0.7945" to 0.7950" and - get this - it's 30 TPI, not 27, 28, or 32 (my guess). There are less than four threads in contact between the nut and the sizer body. The counterbore ID is 0.725" and the thread relief cut under the head has an OD of 0.755", meaning that there is a section of the nut that has a 0.015" wall thickness holding against the upforce from pushing the bullets back out. I don't have a LAM, but I think the RCBS nut is more - robust - in dimensions.

By the way, I looked on my lathe and I have a setting for 30 TPI, but I don't know how standard/common this is. I can say its the only 30 TPI fastener I've ever run into. I'd be really glad if anybody else out there can confirm or refute this as the correct thread pitch.

I'm guessing it might be difficult to get an off-the-shelf tap to clean up what you have, but I could be wrong. The diameter doesn't correspond to any standard fractional size, and the pitch is all wrong. I won't speculate as to why it was designed that way. It may be an optical/microscope sized thread diameter/pitch combination.

The next largest standard size would be 7/8-32, I don't think a 13/16 - 32 would clean up all the way. Whether the Lyman body can be enlarged by the 0.075 - 0.080" needed is another issue.

IMHO the nut is the weakest point in the 450/4500 system which otherwise are reasonably good sizers.

Hope this helps.

[Maven]

Keith, That's exactly the information I was seeking and agree with you completely about the die retaining nut being the Achilles Heel of the #450 & #4500. After using mine for 25 yrs., it became quite obvious that thread engagement is a problem, made worse by their fine, easily clogged nature. The RCBS LAM's, on the other hand, whose die retaining nuts are larger with more and coarser threads, are much more robust and forgiving than the Lymans. Btw, the body casting of the 450, 4500, LAM I and LAM II are so similar that they appear to have been cast by the same foundry.* Thanks so much taking the time to help me!

Paul

*Both LAM's have a small "tail" at the rear of the base, but the LAM II has a solid bottom whereas the LAM I has a bushing and gasket at the base like the Ly. 450 and 4500. In spite of that, my LAM I hasn't leaked at all, but the #450, well that's another story.

[beagle]

Yeah, that's the achilles heel for sure. I was talking with Lyman's customer service once and had them throw 5 new ones in my order. These get tossed in a jar of solvent after use and when I have five, I clean them all and dry. That gets all the lube out of the rings and lets you start fresh anyway. So far, it's worked for me but that is a sure design flaw.

I once measured or had my machinist measure the threads on some 310 die parts. He came up with threads that haven't been used for 30 years. They sure used some strange threads./beagle

[lmcollins]

Just a hint: Whenever I change the die in my 4500 or the late model 450 I used to have I take the nut and place it on a piece of newspaper, and melt the lube off of the nut with my trusty Harbor Frieght heat gun. It doesn't take much time at all, since the lube goes fluid at such a low temperature.

The nut always starts easily, and straight when it has no lube on it.

I've done this for ages, and it always seems to work. A hair dryer would probably work just as well. The nut is small (low mass) and doesn't require much heat to clean the lube from its threads.

[Maven]

lmcollins, That's an excellent suggestion, which I assure you, I WILL be following!

[theperfessor]

Of course, you could get one of my die retention nut drivers and ensure you start the nut straight every time...

[scrapcan]

winchester, ideal, and lyman all used the 30 tpi thread. The small dies use a 30 tpi thread as mentioned above as do some fo the winchester gun screws and reloading tools.

There is some history on this as the originator of ideal, Mr. Barlow, had worked for Winchester.

so there is a bit of esoteric trivia for you.

[crappie-hunter]

Another hint,I take the nut and slip it down over the die before putting the die in the body,this makes it easier to to slip over the rubber O-ring. Works for me.

[MtGun44]

Buy Keith's nut driver, a fantastic tool that starts the nut straight every time! It fits into
the top punch holder and drives the nut straight and centered, every time.

REALLY. I am just a very satisfied customer.

Bill

[Mk42gunner]

So if the Lyman 450 thread is smaller than the RCBS LAM, and is stripped; just how are you going to put the larger diameter nut on it? Braze on a larger diameter sleeve that fits the RCBS thread?

I am not trying to be a smart aleck, but looking at my LAM; I would not want to try putting the casting on a lathe to fit a sleeve.

Robert

[nicholst55]

Anybody know of a source for thread chasers? They might be easier to find than the correct tap or die. They're made in both internal and external styles, and doubtless a few others.

Oh, here you go: thread chasers (http://www.newmantools.com/chasers/index.html?gclid=CPzdt_Owyq4CFQyJpAodRDxzCA).

[theperfessor]

Mk42gunner-
I wouldn't put it on a lathe - it would be awkward, although I have done some pretty weird things with a lathe. I would make a bushing to fit the die cavity and the ram guide and then make a piloted boring bar to fit. I'd put the luber upright on a vertical mill and use the quill feed to bore out the threaded part of the luber to the proper size for tapping. Might have to make an extension to drive the tap and maybe modify the lead of the tap to make it a bottoming style to get full threads.

Would it be a lot of trouble and take a lot of time? Yes, although making the tools would take far longer than doing the actual modification. I think it could be done, but at a cost that not many people would want to pay.

[Wally]

Could be all you need to do is replace the retaining nut--as this happened to mine. When you tighten it down--don't overtighten it and you should be good for years....also, when removing it but a drop of oil on the threads (I use ATF)...keeps the threads clean of bullet lube. Good Luck...

[Maven]

All, Thanks for your helpful suggestions! Upon closer examination I found the threads on the main casting not to be stripped, but filled with lube, as were those on the [new] die retaining nut. After cleaning them both, it threads just fine. Btw, I never had a problem starting the die retaining nut straight into the casting as I follow this simple procedure: Insert the H & I die into the opening in the body. Then take the die retaining nut and place it over/above the die. Use the ram to snap the nut over the O ring on the sizing die, Lastly, tighten it, but make sure you don't overdo it as it will strip: Been doing this for +25 years with nary a problem.


P.S. On the RCBS LAM I & II, you have to first insert the H & I die into the die retaining nut and then thread them into the casting.

[9.3X62AL]

This has been one of the more informative threads here of recent vintage. Good to learn that the RCBS LAM II uses a more stalwart retainer nut that is threaded more coarsely than the 450/4500. I see a second size/lube machine in the near future, and I'm still having trouble choosing between another Lyman and the LAM II. Like others have expressed here, those fine threads and thin walls of the Lyman die retainer nut don't inspire confidence. That said, I have 31 years of service with three 450s, and have yet to strip any of them out. I've been VERY careful when installing and removing dies, though--using the die body as a guide and making SURE it is fully and squarely engaged with the die top, and heating the nut threads with the hair dryer used to heat the sizer body. Soft lubes help a lot with that, I'm sure.

[Freischütz]

Like crappie-hunter I slip the nut over the die before inserting the die in the machine. I've never had a problem since I began this technique.

[Bret4207]

Mr Collins suggested what I was going to- I use the ancient old blow dryer SWMBO tossed to warn the area before trying to put stuff in there. Works mo' bedda.

[Char-Gar]

I have had problems with lube cruding up the threads on Lyman 450 also. I use a tooth brush and a little solvent to clean both the nut and hole in the body of the machine. Like Maven, I thought I had stripped the threads, but found out it was just lube in the threads.

[462]

After aligning the nut and body threads, I punched a witness mark on the nut at the 6:00 position. Now, when I turn the nut it instantly engages the body threads. No more fiddling round making sure the threads are mated.