tips for installing lugs or sights?

so at some point here in the future i'll be cutting and dovetailing the top of the barrel to install the front and rear site...and i'm a little nervous about it. i did all four tennons on the bottom of the barrel and they came out pretty nice but there are some gaps between the tennon and the barrel that formed as i worked the 3 sided file to create the dovetail angle. started with a hack, and filed down to flat and up to that point they were perfectly square and neat. but as soon as i started to work the dovetail they started to dish in the middle. the file does have a safe side (just as a note).

anyway...this is my first build and i'm proud as ever about the tennons...but i'm a little worried that if i bugger up the sights i'll always have to look at them. i'm going as slow as possible...the four tennons took about 3.5 hours..i'd file...look at it...file..step back and look at it again...then look at it some more. just couldn't keep it from getting messy looking. someone told me one option would be to have a smith mill them in for me...but i hate that idea..i'd rather have ugly buggered up dovetails before i let a smith do it for me.

so any tips from you seasoned guys on how to keep things nice and neat when it comes to this technique???

Well i have never filed a dovetail, i haven't got that far in my build yet. So im just assuming but im thinking that you need to make the bottom of the file safe. That way you only remove the material from the side and not the bottom. Like i said im not an expert but that how i understand it.

i did safe the one side of the file...it's not wearing into it but i think part of the problme is that with the one side safe the edge that's still sharp is not cutting the dovetail flush...it's almost riding upwards as it cuts.

They make a jig for cutting one out. I think TOW carries them. But basically you make a series of cuts across the barrel with a hacksaw. Stopping the cuts a little shallow of where you want the bottom of the dovetail to finish to depth. Then it is not as hard to file out the remainder.
There has been posts on this before but a search didn't bring up much.

A google search brought up these: http://castboolits.gunloads.com/showthread.php?t=33233

Once the square notch is cut flat w/ ample steel for the dovetail, I then start to file the actual dovetail w/ the safe side of the file down. When each side has a full depth dovetail,I then file into only the bottom of the corners w/ the safe side up to flatten the whole surface. For the rear sight, I use an upsetting chisel and after sufficient metal has been raised, the bottom of the dovetail is filed to flatten. I then move to the opposite side and do the same. A small amount of steel is left for file fitting the rear sight. The raised steel is filed into a molding. The front sight is the same except no upsetting chisel is used. Yes...the area just below the dovetail will rise whether filing or using the upsetting chisel and has to be filed flat. For bbl lugs, the dovetail is made as for the rear sight, but the raised steel is peened down onto the lug for a very tight fit.....Fred

Fred pretty much aced it. The tip I would add is that I take the time to set my barrel in the vise, so that only the barest amount of the barrel is exposed. This makes the top of the vise a stop for the hacksaw. Its a depth gauge of sorts. If your vise is busted up you could use a couple of pieces of angle iron in the jaws, so you have a clean surface as your guide.

Bill

Bill of the 45th Parallel said:

Fred pretty much aced it. The tip I would add is that I take the time to set my barrel in the vise, so that only the barest amount of the barrel is exposed. This makes the top of the vise a stop for the hacksaw. Its a depth gauge of sorts. If your vise is busted up you could use a couple of pieces of angle iron in the jaws, so you have a clean surface as your guide.

Bill

Click to expand...

Very good idea, thanks.

that's what i was looking for....thanks so much Fred!!! flipping the file safe side up to work the angle never occured to me...and that's the part i was missing. did set the barrel in the vise and leveled it there...and used brass sheeting as a stop on the jaws so i would keep the hack level and not cut too deep.

thanks again...i really appreciate the advise

riggs

all the above ideas are good, and if I can remember I might use some of them. I also make a guard for my hack saw blade with two pieces of 1"X 1/8th" stock nearly as long as the blade. After laying the two together I drill through both pieces and tap one piece so They can be fastened together with bolts making sort of a clamp to go over the blade. I will then use the sight itself to gauge how much blade is to be exposed tighten the blade and saw to where the guide clamp just rides on the barrel. I always mark both sides of the barrel for depth and go SLOW. Several cuts across the barrel then I clean up with a chisel I have sharpened for the task, and proceed with my three square safe sided file. making your file work flat is the hardest thing I run into. I think that comes with practice Not really hard , but tedious. If I have you really confused try doing some dovetails in scrap stock first.

For both sight dovetails only, I use 2 lengths{ 2"- 2-1/2" lg} of drill blanks that are small enough to "seat" into the dovetails to ensure that they're perpendicular to the bbl and that both sides of the dovetail are parallel. Holding the pins into each side and having most of the pin's length outside the bbl, exaggerates any discrepancies. Swamped bbls pose a slight problem using the pins, but anyways for me, the pins always get the sight dovetails right....Fred

You make a triangle file "safe" by grinding off one side of the teeth , making that side smooth, so it can't cut metal as you shape the sides of the dovetails. :hmm: :thumbsup:

If you don't feel competent doing that kind of grinding work, take a file to a local machine shop and have them do it for you. I think you can buy a dovetail file from some suppliers like Brownell's. It has the one side already ground down for you. :wink: