Lyman #45 lubsizer

[Blue2]

I recently picked up one of these from a yard-sale that appeared to be in excellent condition but is missing the cylindrical piston that pushes the lube down the lube chamber . It is difficult to get a measurement on the thread size as it is below the lip of the tube . I can make up one on the metal lath but cutting a small internal thread is challenging so if someone happens to know what the thread and pitch size is then I could probably order a tapping tool and make up a new one . Thanks a bunch if you can answer this inquiry .

[Winger Ed.]

Call Lyman.
If they don't give you one, it'll be pretty cheap, and you'll know its the right one.

[metricmonkeywrench]

The piston is the same size as a new 4500 sizer. The piston and o-rings can be sourced from Lyman and would be considered an upgrade from the original design

Also look here

https://castboolits.gunloads.com/sho...p-instructions

[alamogunr]

I knew someone would come along with a better answer. I looked at mine and didn't have a nut to check threads but if I guess, I would say that it is 3/8-24(UNF).

It could be something real exotic since they put that ridiculously fine thread on the size die retaining nut. I fought that until I bought the wrench from Keith on Art & Science of Bullet Casting.

[JonB_in_Glencoe]

The threaded rod (pressure screw) will just push out of the reservoir...so you can easily measure it.
If it doesn't, the "cylindrical piston" (Pressure nut) is likely bottomed out and stuck at the bottom of the reservoir.

[alamogunr]

The threaded rod (pressure screw) will just push out of the reservoir...so you can easily measure it.
If it doesn't, the "cylindrical piston" (Pressure nut) is likely bottomed out and stuck at the bottom of the reservoir.

My 450 is obviously full of lube. Doesn't take many turns to get the nut out of the reservoir. The only nuts I have in the junk box are course thread and the pressure screw is not course thread. As I said, my guess is .3/8-24 UNF.

I go along with the first two responders that recommended trying to order one from Lyman.

[Tazman1602]

Absolutely call Lyman, they were really easy to deal with for me.

Art

[JonB_in_Glencoe]

My 450 is obviously full of lube. Doesn't take many turns to get the nut out of the reservoir. The only nuts I have in the junk box are course thread and the pressure screw is not course thread. As I said, my guess is .3/8-24 UNF.

I go along with the first two responders that recommended trying to order one from Lyman.

My comment wasn't in response to your comment, it was for the OP.

If the OP is able to make one on a lathe, then he likely has the tools to measure threads. AND if he isn't able to measure the threads, because he isn't able to remove the pressure screw, then I surmise that the pressure nut in bottomed out and likely 'locked' at the end of the threads. So the problem may not be lack of pressure nut, but a pressure nut that is bottomed out in the reservoir.

[Blue2]

I will see if the nut is bottomed out . Busy here over the Holidays with lots of family activities . All vaccinated so no need for panic . Yes the shaft is too deep in the reservoir to get an accurate measurement . The shaft did not want to push out so you are most likely correct in the piston stuck at the bottom suggestion .

[JonB_in_Glencoe]

Bottoming out the pressure nut is a fairly common occurrence.


https://castboolits.gunloads.com/sho...-with-Lyman-45

[alamogunr]

If post #3in the referenced thread is correct that the pressure screw is threaded 3/8-20, Lyman is at least consistent with odd ball thread sizes. I've never seen a 3/8-20 screw/bolt, but then I'm not a machinist

[jaguarxk120]

Almogunr is right, I have a Lyman 45 down for cleaning and checked the pressure screw.
Yes, it is 20 threads per inch, checked with a Brown & Sharpe thread gage.

Best to get the part from Lyman, if needed.

[alamogunr]

Almogunr is right, I have a Lyman 45 down for cleaning and checked the pressure screw.
Yes, it is 20 threads per inch, checked with a Brown & Sharpe thread gage.

Best to get the part from Lyman, if needed.

All I did was report what I read in the thread referenced by JonB and comment that it is a unique thread spec.

[Blue2]

Thanks for all the advise . It was not obvious looking into the reservoir but indeed the pressure nut had bottomed out . It is an older style with a brass seal and the old lube had dried out and seized it solid onto the threaded shaft . Penetrating oil and a heat gun let it come free . Back in business--Thanks a bunch guys .

[Ziptar]

Glad you found it, they get stuck down there and disappear in goopy old lube.

The cost upgrading to the 4500 dual O-ring piston and screw is $19.79 with shipping and is well worth it. The brass seal on the first used 45 I bought leaked like the titanic. When I bought a second 45 years later I didn't even bother with old 45 piston and ordered a new 4500 piston straight off. By the time I was ready to reassemble the 45 after stripping and repaint the new 4500 piston had arrived.
You can order the parts from Lyman direct on their website: https://www.lymanproducts.com/4500-l...lacement-parts

Part#	Price	Desc.
2990708	$6.57	4500 L S pressure nut w o rings
2745820	$0.32	4500 L S Nylon Piston Stop Collar
2990559	$7.90	4500 L S Pressure Screw

Shipping is a flat $5.00. The Nylon piston stop collar keeps the pressure nut from getting stuck at the bottom of the cylinder like how you found yours. You may not need a new screw but on some older 45s the pressure screw did have a different thread. I'd ordered both the 4500 piston and pressure screw for my first 45 but wound up not using the new screw because my old 45 screw worked fine with the new 4500 piston. The the pressure screw on my second 45 was threaded differently than the new 4500 piston. I still had the new 4500 screw I'd ordered a 7 years previously so I just ordered the piston and collar for that one.