how to fixture a vaquero (how to make sure it's level for milling)

[Whiterabbit]

Hi guys,

Help me out. I want to dovetail a vaquero barrel. Blackhawk would be easy, I'd strap it in and put a bubble level on the top strap, then bubble level along the barrel, and off I go. But the vaquero has no flat top strap. Not really....

How do I ensure I get TDC on the vaquero? Do I just put the level across the sight channels, hope for the best, and adjust with the frame wrench if I flub it up a degree or so?

[JMtoolman]

Why not use the inside of the top frame to level it? Just clamp a straight piece of stock on the inside with a clamp, use a pocket bubble level on the piece. Easy peasy! The toolman.

[Whiterabbit]

sounds like a plan. do you figure the frame window is "level" with the barrel?

[JMtoolman]

Why wouldn't it be?

[Whiterabbit]

Because castings that are not post-cast machined are rarely perfect. It would not surprise me if it were off a degree or a few.

On the other hand, if that kind of error can't be seen by the naked eye and it shoots straight, I don't care either.

[kywoodwrkr]

I'd indicate off of a range rod/pin gauge in the front of the barrel to make sure all my angles were straight in my mind in all axis.
The few degrees of taper may not be a problem, but I'd over engineer it I'm sure!

[John Taylor]

Take the grips off and use a square from the table, the grip frame has flat sides.

[lmcollins]

You need to work from the top of your mill table.

If you were to just "level it" with a level you could be all out of wack. You are assuming that the mill's table is level with the floor. Work from the both sides of the frame, and make it square to the top of the table.

Take a square to both sides of the frame and see how they square to the top of the frame, and center the frame sides up as best you can.

[Whiterabbit]

I level my mill table.

But you make a really good point. I should be in the habit of re-leveling the tool every month or so which I am not doing. I will be sure to re-level the table just before fixturing.

VERY good point. In fact, the tester came out imperfect, and that might be a big reason why. I'll bet if I put a level on the table now I will find my X drifted a smidge.

[W.R.Buchanan]

I have Starrett Precision Levels from when I was Millwright. Neither of my mills are level even using a torpenis level.

The reason why is that I have never been a big fan of using a level on a machine for setting up a part.. Typically the levels used in such setups are less accurate than eyeballing. There is seldom a guarantee that the machine is actually level, with the possible exceptions of large lathes which pretty much have to be there or else they turn tapers. And nothing on a Lathe needs to be level anyway.

In this case I would probably clamp the barrel in the vise on top of parallels and indicate it in "X" to make sure it was in the vise strait. With the frame hanging out one side a square on the side of it would define squareness to vertical. Or you could indicate the side of the frame from the quill to insure "verticality." is that even a word?

Then I'd use and edge finder to indicate the edge of the barrel and measure the barrel dia. and divide by two to get TDC or the centerline of the bore.

I think this would deliver all you need but remember when you start tweaking on the barrel to adjust windage you can only go so far before your ejector binds up.

I guess that's why they made adjustable sights?

Randy

[oldred]

Using a level to square a part during set-up is something that I would never trust, the odds of a table being perfectly level are long odds indeed and even if it was then using a level on the work still would never be as reliable as using a square, being squared with the table is what matters and doing so eliminates any possible (probable actually, no matter how slight) leveling errors of the machine itself, there's just way too much room for error when relying on a level.


JM 2 cents

[Whiterabbit]

OK, well I am now working with just the edge finder and my angle block. If I clamp the grip frame to my angle block I should be square to the table. But edge finding the barrel and dividing by two (taking care to reduce error from backlash) yields a position that is very much off center by eye.

Does this imply that I cannot trust the gripframe to be vertically in line with the barrel (and front sight)?

Any suggestions on where to go? try again with the frame? I'm not sure the main frame will be any more likely to be parallel with the front sight.

[dubber123]

It's very much the hillbilly way of doing business, but I just cellophane taped a front sight off a 10.5" BH to the barrel of my .45 Colt BH and shot it and moved it around until groups centered. I then marked both sides of the front sight base, and reattached in that spot. It shoots dead on. If you really stretch the tape tight, it holds surprisingly well, and allows adjustment without retaping.

[nicholst55]

Take the grips off and use a square from the table, the grip frame has flat sides.

Not really; that's why revolversmiiths like Hamilton Bowen charge you big bucks to 'deck' your grip frame prior to fitting of custom aftermarket grips.

[Whiterabbit]

That was understood. As long as it was flat enough to get me TDC within a reasonable tolerance, then it's all good.

Thing is, it wasn't. at least, I don't think?

I took the existing sight off. This left the channel in the top of the barrel. I clamped the grip frame to the angle plate. Rotated the barrel so the top of the barrel was parallel to the table.

Indicated off each side and went to the middle, then put in a 1/4" 4 flute end mill in the collet, and rotated the bit so the tip was by eye, right in the middle of the channel. The opposite flute should be in the middle of the channel on the other side (by eye), yes? Just an idiot check before turning the mill on.

Well, it wasn't centered. Meaning my confidence is low that I nailed TDC.

So I'm kind of rudderless at this point. I don't think the frame is any more likely to be square to the top of the barrel. My only other idea is to just do it "by eye", and drift the sight (I'm cutting a dovetail here) if it's a little crooked. But no guarantees there that the sight will be TDC if I do it that way, I'd really like a way to indicate TDC. I'm just blanking.

[dubber123]

Again, my hillbilly method will assure you your sight is where it needs to be, regardless of how crooked or not your particular gun is. I did it this way, as I WASN'T doing a dovetail, and would have no adjustment after it was done. The way I did it also takes into consideration all the dynamics involved in firing, such as torque as the boolit goes down the barrel. Different weights/velocities will often shoot to different windages, and they do to a small extent in my Vaquero. I got to shoot my gun plenty and find a few loads it liked before affixing my front sight. Btw, the front 10.5" BH sight was well high, allowing me to tune in my loads, and the fatter front fit the gappy factory rear sight cut MUCH better, and the groups afterwards showed it. Good luck.

[fg-machine]

been there done this before , one problem you are going to have when you indicate the part in off both sides of the existing channel is you are assuming that it was cut perfectly from the start , highly doubtful it ever was and truth be told it doesn't need to be perfect , it just needs to be right .

my simple solution was to indicate the frame in as best as i could using the tops of the v notch on the sight channel as a reference point and then cutting the dovetail on the same plane , simple and everything lines up .

the best advice i can give is learn to trust your eyes , they are almost always right .
after that is put the bubble level away, in 20 + years of making my living as a machinist i have yet to use a level on any set up

[DougGuy]

Levels are for pipefitters and plumbers and benchrest shooters. Take the grip frame off and use the bottom of the cylinder frame as a level/square/perpendicular surface, clamp this to a parallel block to find horizontal axis. It won't be parallel longways with the barrel but you can figure out how to block it up, you would want the top of the barrel parallel with the bed so the dovetail will be cut square with this axis, not the center of the bore.

[Whiterabbit]

Thanks for the advice guys, I took it all.

What I ended up with is far from perfect, but I believe will be absolutely servicable, and as folks say here, it will be "right by eyeball", for which my first attempt (on a 1" barrel cutoff) was not! (for the record, it was only slightly crooked, front to back).

Anyways, this is what I ended up with:





And for the record (again!), this is just another "practice", this time "live". That sight will get a patridge profile (also practice!) and taken to the range and shot. When deemed suitable, the whole shebang comes out because the barrel is gonna get cut to 3.5 inches and re-dovetailed for the final sight install.

Cause if it is worth doing once, it is worth doing three times to make sure it ends up right.

[W.R.Buchanan]

Cause if it is worth doing once, it is worth doing three times to make sure it ends up right.

That's my Motto! It's how you get good.

Randy