I made a scope ring lap yesterday from some 12L14 steel and it then occurred to me that in the past, and as a general machining rules, the material used for the lap must be SOFTER than the material being lapped, because lapping compound will embed itself in the softer material. Is this something I need to br concerned about because I think most scope rights are aluminum??
Also, as for the lapping compound, I have 320 and 600 grit clover compound. Is that adaquate and which one should I start with?

Regards,
Kory

Do yourself and get a Clymer or Dave Manson ring reamer. You'll be glad you did, and it'll pay for itself quickly once you start using it. I used to try to lap rings, but it just ain't worth it to spend hours trying to straighten them out when you can have it done in 5 minutes with the right tools.

Maybe someone can help me here. I know what people mean about soft material and embedding but won't the compound bed in both materials, just to a different degree? How can it not embed in one steel just because it is a little softer (in relative terms) to another steel?

quote:

Originally posted by Nobade:
Do yourself and get a Clymer or Dave Manson ring reamer. You'll be glad you did, and it'll pay for itself quickly once you start using it. I used to try to lap rings, but it just ain't worth it to spend hours trying to straighten them out when you can have it done in 5 minutes with the right tools.

And the good thing with those tools is that it is next to impossible to go too far...which ain’t the case with a lapping tool.

A wise man once told me: “Hammers are great tools...but unfortunately all jobs don’t have nails involved?†The right tool for the right job?

Using the steel bar and lapping compound will do just fine. Start with the 320, I really see no reason to use the 600. Get the rings installed and aligned as best you can before you start to lap, like if you're using Leupold dovetail rings, ge them real close. Or, make sure the rings are even height wise. Then lap. It may take several "clean and recoat" cycles, just keep watching the ring for where it's getting worked on. Once the bottom half is done, I take the top halfs, and work them a little on the steel bar while compound is still on it, to make sure there isn't any burrs. You'll easily FEEL the difference when tightening the rings that they snug up positively.

quote:

Originally posted by Nobade:
Do yourself and get a Clymer or Dave Manson ring reamer. You'll be glad you did, and it'll pay for itself quickly once you start using it. I used to try to lap rings, but it just ain't worth it to spend hours trying to straighten them out when you can have it done in 5 minutes with the right tools.

I did not build the standard hand lap that your probably thinking of. This is a powered lap that I saw on a Darrel Holland video and I improved it a bit by adding a handle/bearing on the far side to keep the pressure constant.

Kory

quote:

Originally posted by tiggertate:
Maybe someone can help me here. I know what people mean about soft material and embedding but won't the compound bed in both materials, just to a different degree? How can it not embed in one steel just because it is a little softer (in relative terms) to another steel?

tiggertate,

Before I explain this, let me say that most of my machining experience is in internal combustion engines, so almost all of the lapping I've done has been the lapping of pistons and cylinders.

Now, how have 3 components when lapping: the lapping tool, the part beind lapped, and your lapping compound. There are many different types of lapping compounds, from toothpaste to diamond dust. I use silica carbide stuff like Clover Compound and I'll explain why in a second. The lapping compound has sharp edges to it, it is abrasive, and is it designed not to break down too quickly. Now images having a sharp, abrasive material sandwiched between two items, one hard and one soft. Which one do you thing the abrassive will force itself into? The softer one. So as a rule, you want your lap to be softer than the part being lapped. So if I'm lapping aluminum, I will use a copper lap, for brass, steel, or iron, I will use a aluminum lap, etc.

As for diamond lapping compound, I avoid it like the plague because it does not break down. It will stay in an sharp abrasive state for many years. Imagine what will happen if it little bit of it gets on you lathe bed, a motor bearing, or gears. Over time it will destroy it. Clover compounds breaks down after a little use, so you end up using a lot more, but sand it cheaper than diamonds.

I hope I answered your question and I was clear in my explanations.

Kory

Lapping rings should not require a lot of metal removal, it seems that you can even do a halfway decent job with sandpaper on a dowel....

My advice is that since you made your tool, just go ahead and use it. My preference is after lapping to put a couple coats of rubber cement on the lower ring, letting each coat dry thoroughly then install the top half. It solves any scope creep issues, even on heavy kicking slug guns.

Maybe it is because I have too many specialized tools that cost an arm and a leg and then sit for 10 years, but just use what you have already made and be finished with the project.....