Author Topic: Underlug tutorial  (Read 26282 times)

Offline D. Taylor Sapergia

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Underlug tutorial
« on: April 28, 2010, 06:50:57 PM »
Recently, there were some questions about making and installing underlugs in a rifle barrel.  I have this series of pictures, so have included them in a short tutorial.  Hope it is of use.

I will comment on what is happening in the pictures in due coarse...have to run right now.


I cut a strip of  ~.03125 steel or brass using the top of my vise as a guide.  The strip in this case is about 3/4" wide, inside the vise jaws.

Then I cut off pieces about an inch long, and rough polish the inside for silver soldering.




Here the piece is folded in half...

...schmeared with flux...

...and then squeezed shut.




I place the folded side in the vise between 1/8" and 1/4", depending upon how deep I want the lug, and use a drift, in this case a screw driver, to tap them open onto the top of the vise jaws.  I finish the fold with light taps of a hammer.





Here the lug is hard soldered on a fire brick using a propane torch.  Dull red does it.


The extra silver solder is filed off.

I've used steel ink to help lay out where I want the rectangular holes.  This rifle was getting a very slender barrel, so I laid out the holes to place the key about half way down the forend from the barrel channel.  Here's where your drawing is important, for that planning ahead.  Often, the slot will be level with the barrel once in the dovetail.  Also, this one was getting a key 3/32" thick.



Holes are drilled on the centre punch marks.  I make 'em a few 'thou' under the thickness of the key to allow for filing out the web.  Also, I only needed two lugs for this project, but it doesn't take much more time to make a spare or extra for a future project.

A jeweler's saw is used to cut out the steel between the holes.

...sawing is done.



...filing the slots both in length and width.   I ground down a nice coarse file to a thin 'needle' file.





the slots are filed, as well as the tops of the folded metal, just to square them up and make them pretty.


More steel ink, and the tabs are cut off ready for cutting the dovetailed edges.

This shot shows the lugs set back into the vise, and the triangular safe-sided file I used to cut the dovetails.

Sliding the file over the vise jaws, cutting the ends of the lugs to 120 degrees.

I've used the Vernier's calipers to measure the thickness of the metal that will go into the barrel, locked it, and with the depth gauge end, marked the barrel for the full depth of the dovetail.  Just hold the tool vertical and slide it along the bottom flat (turned down-side-up in the vise).  A felt pen will also do for layout ink.

The big black mark indicates where the centre of the lug is to go, and the scratches either side are the minor dimensions of the male dovetail on the lug.

I use a hack saw to make a series of cuts just short of the scribed depth dines.  Use a new blade, don't rock it, and go slowly, checking almost every fine stroke to ensure that you are not outside the lines.  Here's likely where a novice is going to freak out.  It's not magic - it's mechanics - and you just have to be calm and patient, and go slowly.

I usually use the hack saw tipped at about fifty or sixty degrees to cut away the webs left by the hack saw.  You can also use a cold chisel with a good sharp grind, or file them out.  Again, go slowly and stay inside the lines.  Filing without rocking, and level, is something that comes with practice.

After I've squared the corners almost to my lay out lines, with a parallel pillar file, I use the same three sided file to create the female dovetail cuts.  Stop often, and check with your lug to make sure it isn't oversized.  I like to include a very small taper in the dovetail so that once started, I can go very very slowly to get a perfect fit.


...almost there.  This is not the time to stop for a beer.





The lug is tapped in.  I use a drift I ground from an old nail set.  It has a rectangular end that is nice and square so I don't miss and dimple the barrel.  Also, the  extra metal has been filed off flush with the angle flats of the barrel.  It probably isn't necessary but looks nicer to my eye, and doesn't need extra inletting into the channel.
Now it's time for a Canadian...or a Budweiser!




I've included another underlug picture, this one from a longrifle I'm currently building for Leatherbelly.  I used brass of 1/32" thickness here, and pins that are finishing nails .073" dia.  The pins pass through the stock's web right next to the barrel, and their holes are elongated just a bit with a small needle file.  Here, we don't have humidity issues, and I've never experienced stock lengthening or swelling until I brought one of my rifles to Dixon's Fair.  But I don't take a chance.  The pins or keys sure can't go 'fore and 'aft in the wood, so if it changes length, the elongated slot will make the difference between going merrily along, or having to repair a split forend.
« Last Edit: April 28, 2018, 01:20:15 AM by D. Taylor Sapergia »
D. Taylor Sapergia
www.sapergia.blogspot.com

Art is not an object.  It is the excitement inspired by the object.

Offline Dphariss

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Re: Underlug tutorial
« Reply #1 on: April 28, 2010, 07:13:41 PM »
Nice job.

Dan
No, sir, I don't give 'em $#*!, I just tell the truth and they think it's $#*!. Harry S Truman

northwoodsdave

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Re: Underlug tutorial
« Reply #2 on: April 28, 2010, 10:42:05 PM »
Thanks for the great tutorial.  One would think that hand tools might create a   sloppy job, yet the peice fits perfectly! 

Now I need to try that myself... :'(

Dave

Offline D. Taylor Sapergia

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Re: Underlug tutorial
« Reply #3 on: April 28, 2010, 11:17:11 PM »
That's the spirit Dave.  i am hoping that more builders will step outside their comfort zone and give stuff like this a try.  It's very satisfying.
D. Taylor Sapergia
www.sapergia.blogspot.com

Art is not an object.  It is the excitement inspired by the object.

Offline Ken G

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Re: Underlug tutorial
« Reply #4 on: April 28, 2010, 11:26:09 PM »
Good tutorial Taylor.  Clear pictures showing each step.  Thanks for taking to time to post.  I still remember how terrorized I was cutting my first dovetail into my barrel.

Ken 
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Offline T*O*F

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Alternate method
« Reply #5 on: April 29, 2010, 01:31:05 AM »
I forgot where I got this but it is hot rolled T stock.  It's 11/16" tall and 7/16" wide.  It's multipurpose.  The base is slightly concave for soldering on round barrels.  File it flat to make dovetailed underlugs, or it can be used for sight blanks.

Would appreciate if anyone finds a source as I only have about a foot left.  It sure saves a lot of work.


Dave Kanger

A dedicated person with just a pocketknife can accomplish more than a lazy person with an entire toolbox.

Offline D. Taylor Sapergia

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Re: Underlug tutorial
« Reply #6 on: April 29, 2010, 04:50:27 AM »
A fellow with a milling machine could make that up in no time.  I wouldn't go less than 1/2 wide tho' or you won't cover the entire flat (if that's important to you.
D. Taylor Sapergia
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Art is not an object.  It is the excitement inspired by the object.

Offline smylee grouch

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Re: Underlug tutorial
« Reply #7 on: April 29, 2010, 05:38:33 AM »
Thanks Taylor, you make it look easy. I dont have too much trouble making and instaling the lugs but I shur goof up alot when I install keys through the stock and lug. Is there a tutorial on that topic?   Gary

Offline horseman

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Re: Underlug tutorial
« Reply #8 on: April 29, 2010, 07:08:37 AM »
 Thank you VERY much!!  That took some of the fear out of it!

Offline D. Taylor Sapergia

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Re: Underlug tutorial
« Reply #9 on: April 29, 2010, 06:02:50 PM »
I had a short tutorial on installing slides or keys, but I don't see it in the list now.  Like the underlug tutorial, it got buried when we switched over from .com to .org, I think.  I'll try again.
D. Taylor Sapergia
www.sapergia.blogspot.com

Art is not an object.  It is the excitement inspired by the object.

Offline Rolf

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Re: Underlug tutorial
« Reply #10 on: April 29, 2010, 06:26:26 PM »
Thanks Taylor. That would be a big help. I want to use Keys on the the next pistol project I'm planing. What is a captured Key?


Best regards
Rolf

Offline D. Taylor Sapergia

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Re: Underlug tutorial
« Reply #11 on: April 29, 2010, 09:40:15 PM »
There isn't much sense going to the trouble to make and install keys unless they are captured.  That is they have a slot along their centre through which a pin passes into the wood of the barrel channel, that prevents them from being completely withdrawn from the stock.  It prevents their loss.  If you don't cut the slot and capture them with the pin, you'll lose them eventually.  Most production line rifles do not have this feature.
D. Taylor Sapergia
www.sapergia.blogspot.com

Art is not an object.  It is the excitement inspired by the object.

Offline Tim Crosby

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Re: Alternate method
« Reply #12 on: May 01, 2010, 11:56:55 PM »


Would appreciate if anyone finds a source as I only have about a foot left.  It sure saves a lot of work.



 Try the runners off an old kids snow sled. They are hard but anneal easily and work well.

 Tim C.

Offline B. Hey

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Re: Underlug tutorial
« Reply #13 on: May 04, 2010, 06:47:49 AM »
What an amazing tutorial ... Thanks for sharing so much of yourself and your skills ... Dearly appreciated. Take care .. Bill

Offline D. Taylor Sapergia

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Re: Underlug tutorial
« Reply #14 on: May 04, 2010, 09:10:43 PM »
Thanks for saying so...and you're welcome.
D. Taylor Sapergia
www.sapergia.blogspot.com

Art is not an object.  It is the excitement inspired by the object.

DTCoffin

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Re: Underlug tutorial
« Reply #15 on: May 09, 2010, 08:40:08 PM »
Very nicely presented,I'm preparing for my first build for someone else (father in law has "contracted" me )this will help alot .Thanks

Offline Curt Larsen

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Re: Underlug tutorial
« Reply #16 on: December 23, 2010, 04:03:49 PM »
Taylor, I'm glad you posted this.  It is so easy that I'll never buy an underlug again.  Thanks,
Curt

Offline B. Hey

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Re: Underlug tutorial
« Reply #17 on: January 02, 2011, 03:54:46 AM »
Thanks for sharing your wealth of knowledge so freely and clearly, Taylor. One might easily consider your tutorials as "cyber-apprenticeships" ... Take care .. Bill

Offline whitebear

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Re: Underlug tutorial
« Reply #18 on: January 02, 2011, 07:23:04 AM »
Thanks Taylor for the tutorial and all the other info that you so willingly share.  Hope you and the little lady have a safe, healthy and prosperous New Year.
In the beginning God...
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Offline D. Taylor Sapergia

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Re: Underlug tutorial
« Reply #19 on: January 03, 2011, 07:08:53 AM »
Thanks fellas for the positive feedback.  Often what seems to be routine to some is just magic to others.  I have learned so much from this site - it uses up a considerable amount of space on my computer.
D. Taylor Sapergia
www.sapergia.blogspot.com

Art is not an object.  It is the excitement inspired by the object.

C. HUMMEL

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Re: Underlug tutorial
« Reply #20 on: March 09, 2011, 04:36:03 AM »
        Thanks for the tutorial, hope to put this great information to use!
                                                                                              Ernie

Offline Micah

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Re: Underlug tutorial
« Reply #21 on: March 23, 2011, 12:46:57 AM »
Very excellent work Taylor. This may be a stupid question but what is the purpose of the silver solder? Wouldn't soft solder work as well or even no solder at all?

Michael Markey

Offline D. Taylor Sapergia

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Re: Underlug tutorial
« Reply #22 on: March 23, 2011, 01:46:21 AM »
Soft solder would likely work fine.  I always file the fold down 'til it's flat, and to thin the lug vertically.  With no solder, it will fall apart.  I use silver solder and the part becomes one solid piece of metal.  I find it easier to do than soft soldering too, especially on steel.
D. Taylor Sapergia
www.sapergia.blogspot.com

Art is not an object.  It is the excitement inspired by the object.

Offline B. Hey

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Re: Underlug tutorial
« Reply #23 on: March 31, 2011, 07:22:13 PM »
Like so many of the more experienced builders, you have again chosen to freely share your knowledge and expertise so all may benefit. Thanks, Taylor! You and others like you continue to capture my interest and heighten my desire to move forward in the craft. Take care .. Bill

welafong1

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Re: Underlug tutorial
« Reply #24 on: April 01, 2011, 04:14:14 AM »
dear sir
what a wonderfull tutorial can not say how much i enjoyed it. the pictures were great. thank you
very much i learned a lot
richard westerfield