Guys,

I tend to use Weaver Grand Slam steel bases. Is nice to be able to share spare scopes between rifles. I have two rifles that have exactly the same slot spacings. To get a third and fourth to work the same way, I'll have to tig up the slot in the front base and remill the slot at exactly the right distance.

Not difficult to get the spacing correct with a DRO. However, have not milled tig welds before. Is it particularly difficult?

Totally and completly depends on the filler rod used. Use soft rods and you get soft welds. Use a rod for hard facing and you'll get welds that require carbide tools to cut.

Mike,
get a strip of unslotted steel "blank" and a set of counter sinks for the cap screws.

Rusty,

OK ... you caught the obvious. Was thinking of the equivalent of ER70S mild steel MIG wire. What is the equivalent TIG rod?

Jeffe,

Have even thought about making new mounts using Mark Stratton's approach. The mounts he made for the Ottmar rifle are just beautiful.

But, the cheap shot is to weld up the slots and recut the existing mounts. Have a friend with a tig machine who can probably do it well, and we can blue things. Thought I might try that before getting more exotic.

Only blank I find at Brownell's is B Square and it is aluminum. Did I miss the right one?

quote:

Originally posted by mstarling:
Rusty,

OK ... you caught the obvious. Was thinking of the equivalent of ER70S mild steel MIG wire. What is the equivalent TIG rod?

It also depends on the base material. Your ER70S MIG wire will work fine. I use ER70S2 for my TIG filler. Hell, a clean, stripped, wire clothes hanger works good in a pinch. Whatever you use, if you have a hard time machining it, you might consider going back over the area with a torch to neutralize things a bit. I use carbide only and am not bothered by such things. Good luck!

Most bases are 12L14, which is weldable, but not always the most friendly to weld. On soemthing like that I would use Praxaire's 70S2, which is their name for the same rod mentioend above.

If this is really hot and then cools at a decent rate, you will get hard spots in it. Anneal as per Malm and it will cut very smoothly. Well, about as smoothly as 1018 anyway.

Watch that 12L14 though. Some vendors who specialize in "tactical" accesspries make a stronger Weaver base-often 4142. Just soemthing to consider if the leaded bases give you fits.

Thanks Guys,

Will make a mandrel to mount the thing on, weld up the slot, heat the mandrel and sight to annealing temp and put it in a pot of vermiculite to cool slowly.

We'll see what happens. If it doesn't work those bases are cheap. Would love to find that they made them uncut. Would be the cheapest way to go!

quote:

Originally posted by mstarling:
Will make a mandrel to mount the thing on, weld up the slot, heat the mandrel and sight to annealing temp and put it in a pot of vermiculite to cool slowly.

I wouldn't go to that extent. Just back the flame off "slowly" and then cover in lime. Just back it off "slowly" and let it air cool. Buy Carbide!

This reminds me of two things:
1) My terrible TIG welding last night on a Mauser trigger
2) Your last AR thread on Weaver slot distance

Carbide is not always the answer. Carbide is only best when a good highspeed cobalt at low rpms won't work. The problems with carbide are multi-fold. In order to run @ carbide speeds ya' gotta crank up the rpms. Now if not enough feed is used your cutter is rubbing and compounding the problem by hardening the surfaces being cut. Carbide also is not as impact resistant as HssCo(I like OSG)and chips easily, now you don't get a smooth finish. Unless you flood cool carbide it can shatter due to cooling too fast.

I only use carbide when I cannot get the job done with good HssCo. I have over the past 16 years run across many toolmakers that think carbide is the greatest since zippers. I am of a different opinion. I learned about the real problems of carbide from an "old-school" injection mold maker. He took the time to answer every question I had about why we were doing things the way we were.

Just wanted to pass this along.

quote:

Originally posted by drewhenrytnt:
Carbide is not always the answer.

In a busy shop it is. I don't have time to stop what I am doing to resharpen a cutter. Carbide saves valuable time. Of course a person should have a solid grounding in HSS fundamentals and should be able to "fall back" to it in the event his favorite tool supplier is closed on Sunday and the only thing available is an old HSS cutter laying in a box in a dark corner of the shop.

quote:

Most bases are 12L14, which is weldable

I would not recommend welding on 12L14. The "L" stands for lead. Lead fumes are very hazardous.

quote:

Originally posted by aleaddict:

quote:

Most bases are 12L14, which is weldable

I would not recommend welding on 12L14. The "L" stands for lead. Lead fumes are very hazardous.

Seems too me that everything in the gunsmithing business had lead hazards. What's one more?

Thanks to tnekkcc I remembered that I could mill the front edge of the slot to make it wider and still have them work. That did the job nicely.

Also found a set of aluminum mounts for a Mark X in .264 Win Mag that would allow me to do the same thing. So did them too.

Now have four rifles with exactly the same scope mount centers (4.370") which allows me to swap scopes around without moving the rings on them.

Did find a carbide cutter in the box and it worked with dispatch

All of this will do until I get the materials and time to make real mounts ala Mark Stratton. (Maybe I should say "try" to make them )

Thanks Guys!

quote:

Originally posted by aleaddict:

quote:

Most bases are 12L14, which is weldable

I would not recommend welding on 12L14. The "L" stands for lead. Lead fumes are very hazardous.

Do you wear a gas mask every time you shoot a single shot? Shooting about 4 .22 Long Rifle shells will expose you to a hell of a lot more lead than welding up 2 slots in bases.

The whole lead ban thing has totally gone off the deep end. While it is not innoccuous, the entire concept of scale has been lost on the alarmists. Hopefully it will settle down long enough for me to resume eating my paint chips. I wash them down with a nice Islay single malt.

http://www.key-to-steel.com/default.aspx?ID=CheckArticle&NM=181

quote:

The sulfur content of free-machining steels will range from 0.07-0.12% as high as 0.24-0.33%. The amount of sulfur is specified in the AISI or other specifications for carbon steels. Sulfur is not added to any of the alloy steels. Leaded grades comparable to 12L14 and 11L18 are available.

Unless the correct welding procedure is used, the weld deposits on free-machining steel will always be porous and will not provide properties normally expected of a steel of the analysis but without the sulfur or lead.