Home made ring lapping tool ?
- Thread starter FatCatsDad
- Start date
- Location
- Western Manitoba
I use a lapping bar mostly to verify to myself that the rings are concentric to each other - not tilted up or down or side to side. Some years ago I had one made by a machinist - I wanted to install a 26 mm scope in 26 mm rings, but could not find that size to buy - the machinist guy just made centers on each end of a rod, and turned the thing to 26 mm - I am guessing circa 12" (30 cm) long or so. It looks shiny and smooth, like a hydraulic cylinder shaft - might have been ground to get that finish on it?
I do have a metal lathe here - but I have never been able to get that finish when I turn something - not sure that I could get to "dead nuts" 26 mm either - at the time, it made more sense for me to have a "pro" make one.
I do have a metal lathe here - but I have never been able to get that finish when I turn something - not sure that I could get to "dead nuts" 26 mm either - at the time, it made more sense for me to have a "pro" make one.
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Re: unless receiver holes are crooked and not on the center.
Not sure what your receiver is, but that is a possibility, especially if it's a milsurp receiver.
Are you sure the scope tube is not bent?
If your scope sits nicely [all the way to the bottom with no gaps or light showing through] in the rings, but you cannot move the crosshairs over enough to centre to bore-sight, I'd say your scope base holes are not drilled parallel to the bore.
What are the chances that 2 mounts & 3 sets of rings are all pooched?
Personally, I do not care for them, but have you considered the Redfield style, now made by Leupold & Burris [those mounts have windage adjustment in them] or the Weaver Grand-Slam rings, if you are using Weaver type bases?
Burris also makes Z-Rings, which have offset plastic inserts in them, to correct any zigs and turn them into zags.
Not sure what your receiver is, but that is a possibility, especially if it's a milsurp receiver.
Are you sure the scope tube is not bent?
If your scope sits nicely [all the way to the bottom with no gaps or light showing through] in the rings, but you cannot move the crosshairs over enough to centre to bore-sight, I'd say your scope base holes are not drilled parallel to the bore.
What are the chances that 2 mounts & 3 sets of rings are all pooched?
Personally, I do not care for them, but have you considered the Redfield style, now made by Leupold & Burris [those mounts have windage adjustment in them] or the Weaver Grand-Slam rings, if you are using Weaver type bases?
Burris also makes Z-Rings, which have offset plastic inserts in them, to correct any zigs and turn them into zags.
- Location
- Western Manitoba
As some will know - maybe the holes were indexed correctly and tapped to the receiver, and then the barrel installation was "off line" - I know some of the inexpensive Cooey .22 rimfires had "pressed in" barrels - not sure how fussy they were to align with the receiver, since they used barrel mounted iron sights - might become an issue when you mount the scope to the receiver, and assume that the receiver is pointing to same place as the barrel is. Similar with the older "slip fit" Ruger 10-22 barrels, and I understand many "Made in China" SKS also had similar barrel installation.
I now own a Forster Jig for finding locations of the scope base screw holes, but I notice the thing indexes off the exterior of the barrel - not off the receiver.
I now own a Forster Jig for finding locations of the scope base screw holes, but I notice the thing indexes off the exterior of the barrel - not off the receiver.
Wood and emery cloth is useless.
Buy a foot of ground round 1 inch steel. With 120 grit lapping compound and oil (replenish as needed) and in the mounted bottom ring halves push it forwards and back while rotating it slightly until the rings halves show complete lapping or close to it. Remove all oil and grit before mounting scope. The top halves of the rings receive no lapping. They will correctly line up with the scope on top of the lapped bottoms. I usually spread a little powdered resin in the rings before mounting the scope.
Most steel supply places carry "shafting" aka TG&P (turned, ground and polished), aka "Atlas shafting" in common sizes.
Industrial supply places - some will carry "drill rod" in 36" lengths - essentially TG&P but in a harden-able type of steel.
Industrial supply places - some will carry "drill rod" in 36" lengths - essentially TG&P but in a harden-able type of steel.
Jonnyofalltrades
Regular
- Location
- North-central Saskatchewan
Actually, it's worse than useless, as sandpaper or emery cloth has a propensity to abrade the low spots as well as the high spots. It's flexible. A lap is rigid, and will unly cut away the high spots.
1" round bar is available at any steel supply place. TG&P is what you want. 30mm might be a different story. I don't know, I just machined mine.
BigUglyMan
CGN Ultra frequent flyer
- Location
- New Scotland
Why would someone buy the proper tool when they can make a half-assed version for half again as much?
Jonnyofalltrades
Regular
- Location
- North-central Saskatchewan
Well, if you didn't notice, neither the 1" or 30mm are in stock, and at $55.99USD, you're looking at $110CAD by the time you get it in your hands.
You can buy a lot of TG&P for $110.
Considering it is out of stock and $55 US before shipping... you would be paying considerably more to order and import that tool from Brownell's than to full assed make one.
And it does not require a handle, simply holding each end while sliding and twisting it works just fine.
Eaglelord17
CGN Ultra frequent flyer
- Location
- Sault Ste. Marie
Sounds like they burnished it to me, it creates a high grade smooth finish which is harder than simply turned steel.
FatCatsDad
CGN Ultra frequent flyer
Nice
