Scope ring lapping.

R

reynolds357

New member
I have a question about lapping compound. Is it valve grinding compound? I am about out and the valve grinding compound is a whole lot cheaper and the auto parts store in town has it.
Question 2: Anyone remember that thin paper tape Redfield used to ship with their rings many, many years ago. Does anyone know where to get a similiar product? I lapped a set of rings just a bit big on a rifle and am going to have to fill some space back up. Still only have about 85% contact. Crappy drilling on the action.
 
I've never used valve compound, but have heard it works, though I'm not sure of the grit size in it. I make my own using oil and carborundum powder. It's the same stuff you jewel bolts with using a small round wire brush. You can get it from Brownell's, or several polishing suppliers. The oil is just something similar to 3-in-1, which you mix the two into a paste, and you have it.
 
I have been using the signature rings since they first came out. I love them. They are especially handy on long range rifles. This scope is going on a pretty rifle.;) The only thing I don't like about the signatures is they are ugly. Too ugly for this rifle.
 
It is not valve grinding compound. Its a lapping compound that is used to repair diesel engine injectors that where common 30 years ago. Its a very fine compound. You will probably have to go to an diesel injector and pump repair facility to gAnd if you are looking for pretty rings try Conetrol.
 
What is the diameter of your lapping rod?While you lose some to embed and breakdown,a ballpark idea is you will cut rod dia plus 2x grit size.So,I'd expect about .003 to .004 with 500 grit .005 to .006 over mandrel size with 320 grit,.007 to .008 with 240 grit.

Do a test run first,I assume no responsibility!!Start with finer grit and upsize by going coarser.

If you have already lapped to 1.005,and your tube is 1.00,do not crush your tube to an oval,add .0025 shim.

The automotive Clover compound is workable,but not my first choice.

I would guess Brownells still sells lapping compound,I like aluminum oxide.
 
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I can get aluminum oxide cheap by the pound, I may just use it.
This particular setup is on a WBY Mark 5 that was made in Japan. We all know how notorious the Japanese Weatherby's are for being drilled in a much less than precise manner. Do yall remember the thin crushable paper tape Redfield used to put in the boxes with their rings. They sent 4 pieces of it. It was not intended to be used as a shim but a crushable material that would really "weld" the scope and rings together.
 
I believe it's more to do with who made the lapping rod, as its size will dictate the use of the grit. Mine, I can use something around 240 grit, which cuts fast. If it is a tight fitting rod, and you have to use a finer grit, you will work harder to get it to size. The main thing, is to check it occasionally with an inside mic, or a caliper, as you proceed. I use a spring-loaded ID gauge, that I measure with an external mic.

Preferably, the rougher the inside finish, say stopping off at a 240 grit, will grip the scope tube much better than a highly polished finish, which could allow slippage under recoil. This is an instance where fine lapping is actually unwanted, as it is used to make something slide easily.

Grit Size Conversion Table

http://www.mediablast.com/grit-size-conversions.php

From Sinclair (Brownell's) lapping instructions:

"The aluminum oxide lapping compound included in this kit is 280 grit."

http://www.sinclairintl.com/userdocs/learn/Sinclair_Lapping_Tool_Kit_Inst.pdf

Compound from Brownell's:

http://www.brownells.com/gunsmith-tools-supplies/metal-prep-coloring/abrasives/lapping-compounds/silicon-carbide-abrasive-compound-prod1142.aspx

Caswell Aluminum Oxide 1 lb 240 Grit (320 next grit);

http://www.caswellplating.com/aluminum-oxide-1-lb-240-grit.html
 
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