Home Forums Hunting & Shooting Gunsmithing 30mm lapping bar

I need a 30mm lapping bar. Anyone have one to sell?

You can buy a 12" piece of 30mm aluminum rod here: http://www.mcmaster.com/#standard-aluminum-rods/=11
s2spy

Roll the lapping abrasive into the surface of the bar on a hard surface and you have the perfect lap.

RAN

McMaster-Carr is an excellent suggestion for a source for the Aluminum round stock from which to make your lapping bar, they also have lapping compound in many types and grits. McMaster's shipping is reasonable and in most instances you have your package in a few days without paying for Priority shipping. Seldom if ever are any itmes out of stock and they have nearly everything you sould imagine for all your projects. I order from them frequently, used them for more than 20 yrs. with no complaints. MSC is another good source.

Thanks, guys.

What brand of rings are you lapping??

Talley.

You have to be very careful using an aluminum bar as it will embed itself with your lapping compound and it more than likely is softer than the rings you are lapping. PM me - maybe we can work something out.

Offshoreman,

Thanks for that heads up. I found a steel lapping bar.

NP - glad you got what you need

That is exactly how a lap is supposed to work! I suggest you research laps and how they work as you apparently don't understand the process.

RAN

Wrong! A lap is supposed to be softer the workpiece. The abrasive is supposed to embed in the softer lap metal and then will cut the harder ring material much like a hard bar with fine abrasive paper wrapped around it. Your steel lapping bar will likely force abrasive to embed in the rings as well as the bar and the cutting action will be random and slow. When you mount the scope, any sliding of the scope in the rings will tend to leave nice scratches on your scope tube finish.

RAN

I understand that but when lapping a barrel with a lead slug imbedded with an abrasive, your purpose is not to true the barrel, but to smooth out irregularities. All the ring lapping and truing bars that I have seen, including the set that I have are very hard machined steel. I guess the people selling those ring lapping/truing kits are just dumb old country boys like me. I'll pass on your words of wisdom to them.

Also most aluminum round bar is extruded soft aluminum, not machined or held to any exact tolerances. Not sure how that would lend itself to "truing" aluminum or steel rings.

^^^^^^^^^^^^^^ !!

this is a 10X

I keep the stuff around, in various sizes,....just threw a quick check at some 1" Aluminum stock, it's AT LEAST .005" oversized, and is anything but ROUND, in the precision sense.

....guess it would be cat's azz for lapping in an oversized scope.

GTC

You are just a dumb aze old country boy...

From the Sinclair catalog:

"Sinclair Scope Ring Lapping Tools ( 1 inch, 30mm, 34mm, 35mm) are made from ground accuracy stock stainless steel that has a tolerance of +/-.0005 inch. Each Sinclair Lapping Tool comes with the lapping bars are 10 inch in length, which gives you plenty of stroke length to quickly lap your scope rings."

"Ground accuracy stock" doesn't qualify as "very hard stock" what ever the ffuck that means...

Brownells lapping bar:

"SPECS: Mild steel, in-the-white. 12" (30cm) long, 1" (2.5cm) or 30mm (1.187") dia. Includes (2) plastic handles and instructions."

Please expound on your theory how a lap made out of a "very hard material" can be imbedded with abrasive and then form cut the base material. In 35 years of actual precision lapping I've NEVER seen or used a lap made out of "very hard material".

This discussion is getting out of hand - this was supposed to be about truing and lapping scope rings which can be aluminum or steel. In my humble opinion, I can not see a benefit in using something like an extruded aluminum rod would be of benefit for truing a scope ring. When you are lapping a barrel, your lap is NOT being used to do anything but smooth out minute surface irregularities. If you want to true scope rings would you use a lead slug or even an aluminum slug?

I use the Sinclair scope ring lapping/truing kit commercially made and accepted by industry. When I described it as hard, it is very much so compared to aluminum. Hard for the simple reason that it is much more prone to keeping its original tolerance during use than a piece of aluminum.

All I was attempting to do was keep someone - just in case he did not know - that it was not a good idea to use a piece of extruded aluminum bar stock to lap or true scope rings. That was the only point I made. Was it good advice, I think so. If in using the term "very hard steel" which I meant relative to aluminum, I mispoke technically, I apologize to all of you.

Some of you guys create such an environment of intolerance, you defeat the purpose of an open forum.

First off you are out of your league when discussing metallurgy. No one considers mild steel to be "very hard" as opposed to aluminum. Secondly, I'll bet you never thought of getting a piece of OVERSIZED aluminum roundstock and TURNING IT DOWN TO DESIRED SIZE BETWEEN CENTERS ON A LATHE.

Why people like you feel compelled to comment on something that you are obviously ignorant of escapes me...

Sir, if I there is something personal here to be discussed, why do't you PM me rather than continue this on a public forum. I apologize to the forum for the direction this discussion has taken.

AJ300MAG.........LAID OFF LAZY AUTO WORKER, WITH VISIONS OF BLOATED SELF WORTH