Who's a pro at Borden Bumps?

[JRM850]

I've sleeved bolts before but never tried bumps so any advice I can get will be greatly appreciated.

The rear bumps don't worry me, but right up under the lug for that lower one on a 700 has me a bit concerned about heat management. My plan is to mill a close fitting aluminum heat sink and to "dot and cool" using a .040" tungsten and some 70s2 rod. Am I on the right track? Should I be using different rod?

Thanks,
Jeff

 

[f21sh]

Bumps

HINT do not use heat and metal.

 

[alinwa]

Well, Borden's "a pro at them" I guess, and the one Borden retro-fitted 700 bolt I've got isn't welded, Jim epoxied or soldered the rings on. I can't imagine any gain in welding a buildup.

???

al

 

[Jkob]

Why not dovetail some inserts into the bolt, no heat and they will stay put if tight.

 

[JRM850]

Well, Borden's "a pro at them" I guess, and the one Borden retro-fitted 700 bolt I've got isn't welded, Jim epoxied or soldered the rings on. I can't imagine any gain in welding a buildup.

???

al

It doesn't get any more pro than that! I thank you very much for sharing that.

So it looks like a bushing with a raised boss under under the lugs and matches the bolt diameter everywhere else? This action is slightly larger up front than it is in the rear so I think this is the concept I want to use.

I'm not sure where I got the idea that tig'ing was the method, I think it was from a thread on Longrange shooting where they were talking about putting two tig dots on the lower side and a single up top. Images of the process are pretty rare on the web other than Jim Borden's patent drawings which depict a homogeneous product.

f21sh- Thanks for the HINT
I would definitely keep the heat at the lug under 625. The bigger problem probably would have been hardening of the bolt steel under the drop because of the fast cooling. I would have always been worried in the back of my mind about the stress riser and the potential for cracks in a critical place. I have a furnace so I suppose I could use 4130 filler and heat treat the whole thing afterwards, but I'm better at warping $#!^ than most. I guess the real intent of the question was affirmation.

So the NEW plan is to cnc the bushing profile with .025" sidewalls on the un-raised diameter, undercut the bolt slightly for clearance, single slit the bushing if I can get it over the bolt like a mauser extractor retainer, and devcon, Marinetex, or jb weld in place. I won't be removing any more material in my undercut than I do when I sleeve so I really can't see much downside doing it this way.

Thank you both for your advice.

Jeff

 

[alinwa]

Some things I've heard about and seen re Borden Bumps.

First of all, I'm no expert but have had Jim do some work for me and have used several of his actions both the in-house and the older TPE's...and have handled some retro-fits.

It's been suggested that Borden's Bumps aren't always concentric with the bolt body but are instead scrupulously fitted with offset for better alignment. I've also heard of people fitting rings to 700 bolts with an offset, like "cams" instead of concentric bushes.

I've known of a number of successful fittings where the fitter used JB Weld and double-split (two pieces) rings and this is in fact the method I'd use as the thought of soldering two separate pieces on correctly makes my shoulders ache. I don't like the idea of single split rings being forced over the bolt body....

So, no help here, but my thoughts

al

 

[lngrng]

Borden Bumps

Al,

I remember Jay McMunn (JayIdaho) telling me about using modified woodruff keys to make the bumps. Sounded like a neat way to add the bumps, and if I remember, he machined a small "dado" (slot) in the bolt body in which to insert the key. As you know, Jay was quite the experimenter.
I also remember that he started converting Remington bolts to use the Savage bolt heads very early on.

Nothing good is accomplished by sticking to the status quo..........one needs to try new methods and see just what can be accomplished. Many attempts will result in failure, with a small percentage resulting in success, but not trying new ideas never improves things............I truly appreciated Jay for his refusal to adopt the status quo, instead, always trying new things.

 

[alinwa]

Jay was Da Man...... miss that SOB

 

[Dans40X]

I've fusion TIG weld 1pc & 2pc sleeves on hundreds of customers bolt bodies over the years.
Think.....PURGE !!!!!!!
Sleeves were installed from the aft end of the bolt body, 'cause the handle's were removed to re-LOCATE & TIME for primary extraction.

Less heat than soft soldering

Guaranteed for life !

Epoxy works for those w/o fusion/fillet options.

 

[alinwa]

I've fusion TIG weld 1pc & 2pc sleeves on hundreds of customers bolt bodies over the years.
Think.....PURGE !!!!!!!
Sleeves were installed from the aft end of the bolt body, 'cause the handle's were removed to re-LOCATE & TIME for primary extraction.

Less heat than soft soldering

Guaranteed for life !

Epoxy works for those w/o fusion/fillet options.

Note that this is from a guy who can write his name on a gum wrapper with a TIG, NOT your average bear.....

 

[JRM850]

Al,

I remember Jay McMunn (JayIdaho) telling me about using modified woodruff keys to make the bumps. Sounded like a neat way to add the bumps, and if I remember, he machined a small "dado" (slot) in the bolt body in which to insert the key. As you know, Jay was quite the experimenter.
I also remember that he started converting Remington bolts to use the Savage bolt heads very early on.

Nothing good is accomplished by sticking to the status quo..........one needs to try new methods and see just what can be accomplished. Many attempts will result in failure, with a small percentage resulting in success, but not trying new ideas never improves things............I truly appreciated Jay for his refusal to adopt the status quo, instead, always trying new things.

I think I have seen this method. Looks like he cut a dovetail and used a sight blank? It looked pretty cool, kind of like a woodworker's dutchman.

I've fusion TIG weld 1pc & 2pc sleeves on hundreds of customers bolt bodies over the years.
Think.....PURGE !!!!!!!
Sleeves were installed from the aft end of the bolt body, 'cause the handle's were removed to re-LOCATE & TIME for primary extraction.

Less heat than soft soldering

Guaranteed for life !

Epoxy works for those w/o fusion/fillet options.

Thank you Dan.

Do you fusion weld the front of the sleeves under the lugs as well? Are you talking about gassing a purge chamber or upping the flow to help cool the weld?

Jeff

 

[WSnyder]

FWIW: Not to take anything away from Jay, Idaho (he shared a lot of great information) I believe the originator of dovetailing bolts was Bill Leeper. http://benchrest.com/showthread.php?50894-splitting-sleeves-for-bolts

 

[Dans40X]

Do you fusion weld the front of the sleeves under the lugs as well? Are you talking about gassing a purge chamber or upping the flow to help cool the weld?

If your question is to fusion TIG weld the sleeves "under the lugs"-NO
Depending on sleeve thickness-break fwd & aft ends after installation.
For single slit or double slit/2 piece bushings they were fusion TIG welded longitudinally/length wise.
Single slit bushings were turned eccentrically(bump),then indexed to the body & fusion TIG welded.
Purgeing-
Purging complete bolt body- internally.
Increasing torch flow from 15-20 cubes to 40-60 cubes to cool weld is IMPOSSIBLE & a waste of gas.

Ti,In,Mo parts are welded inside a vacuumed/UHP Argon purged lexan tank specifically made for the purpose.

Changing/mixing gases will increase heat range & weld characteristics w/ adjusted flow rates.
ie
Helium gas-increases heat range by 30% but requires 3X gas flow compared to UHP Argon.

 

[JRM850]

Depending on sleeve thickness-break fwd & aft ends after installation.

I understood most of what you were telling me except this^.

Purging complete bolt body- internally.

Ah. I'm assuming this is to prevent oxidation inside the bolt? I'll show my age a bit here... When I was in gunsmithing school I was taught to put motor oil inside barrels when soldering quarter ribs, barrel bands etc. The oil smoke would displace the 02. That smell...

Welding is an art form. I'm functional, but there is a gulf a knowledge between me and someone that can call themselves a welder. I appreciate your help.

 

[KeithBB]

 

[JRM850]

Thought I would update the thread in case anyone was interested...

I CNC'd some bump rings from 4130 with .015" wall thickness and gave them a single split. I cut recesses on the bolt .020" deep. The rings slipped over the bolt without any problems. After trial fitting I used JB to secure them and O-rings as clamps. I'll let them cure for a couple of days and then turn to give .001" total clearance. (.701" rear, .703" front). After that I will soften some sharp edges if needed and maybe a light lap on the lugs again.

I should also thank Jim Borden himself for sharing his patented idea with the shooting community.