The project that I was interested in starting this morning hit a roadblock when I didn't have a piece of suitable material. I need a piece of steel tubing about 0.325"(+) OD with a 0.225(-)ID approximately 6" long. Putting half a foot of daylight in a piece of steel rod just isn't that appealing. If I don't find something suitable, maybe I'll bore out a spare 0.177 cal barrel--a .22 cal might even work.
In the mean time, there was another project that I wanted to try to make. I've always made scope levels that attach to the scope tube using an old ring. I've seen the B-Square (well, I've seen the pictures) that attaches to the dovetail and I thought that was an interesting idea. I don't know how they keep the mount from rocking upward from the clamping bolts on a 3/8" or 11mm dovetail.
I was interested in making the clamping mechanism for the dovetail attachment so it could be adjusted for level across the top of the gun. We'll see if it works. As I write part one, I truly don't know.
Half inch by half inch.
Chucked in the 4-jaw, roughly centered, then cut off hoping to get a relatively square end.
Ended up using a dial indicator to center the piece. It was actually fairly easy to center using the flats.
I'd purchased a cheap level at Harbor Freight a while back just for the bubble inserts. Took the level apart and have three of these. 3/8" diameter.
Spotted, then drilled 3/8" approximately 0.500" deep.
A small boring bar finished the bottom of the hole.
Set up the Taig lathe horizontal milling attachment. That's a 60 degree dovetail cutter. Small, delicate, expensive things. I almost destroyed this one the first time I used it. Resharpened it and it's still good to go. Played with the cutting speeds and it does better when run faster.
Used a lot of cutting fluid. The fluid lets the tool run at lower temperatures and prevents chips from binding to the edge of the cutter. A better finish results.
Tried a new (to me) cutting fluid. Cool Tool 2--worked fine, but it kinda smells like vinegar.
Bubble test fit is a go.
The dovetail is too narrow. I went back to the mill and made it wider.
It was far too long.
Milled the just-cut end.
A little layout fluid to mark some holes. It'll get drilled as one piece for alignment then cut.
A couple quick passes of a file flattened the base.
A few more steps later...
Derrick -
ReplyDeleteFirst, I want to say I am fascinated by the projects on which you and Nick work. I am no machinist, but I have aspirations of pursuing that as a hobby someday. I do have, however, an extensive amount of experience in woodworking, and I'd like to offer a tip that is used in that craft that might have an application to the work you describe here.
You made a comment about the fragility of the dovetail cutters. Woodworkers, when cutting a long dovetail slot, will often make the first pass with a straight router bit to hog out a majority of the material. They then follow up with the dovetail bit on a final pass. I'm wondering if you could follow the same process here - make the first cut with an end mill to remove most of the metal, and finish up with the dovetail cutter.
Paul,
ReplyDeleteYep, you're right on the money. I should have made (or at least made mention to) such a cut exactly as you've described. I was too lazy to make the cut--largely, because the dovetail cutter was already damaged and I have a brand new spare. Didn't feel like I had much to lose.