Friday, November 13, 2020

Small Mill, Big Vise

When I won my $500 All Industrial Supply shopping spree at the Bar-Z Summer Bash in 2018, my first inclination was to buy a Kurt vise for my machine.  However, after looking at the dimensions, it seemed that even the smallest vise was still too big for my tiny machine table.  The bolt locations would not have lined up with the T-slots, and I would've had to make a fixture plate to mount it.  Even then, there might've been an issue with the vise handle interfering with my machine's Y-axis handwheel.  Not wanting to risk all this confusion, I remembered that my friend had won several vises at an auction which he wasn't using.  He was kind enough to let me have the one of my choice.

I ended up spending the $500 on other things.

The vise I chose was this large two-piece one, shown here next to a standard mill vise for comparison.  The thing I liked about this one, aside from virtually unlimited holding capacity, was the height of the jaws. By itself, the back jaw practically doubles as an angle plate!

The method I chose for bolting it to my table was to machine two rails.  This would require much less material than one solid plate, especially since this is not only for mounting the vise, but also lifting it higher to reach the machine spindle (see the Vise Support post about that problem).  Again, another reason I like the tall jaws, I won't have to raise it quite as high as that smaller vise!

I started with some scrap pieces of steel, and worked the dimensions based on those from my machine table's slots, and the new vise's bolt locations.

First, cutting the pieces to length with the bandsaw.
I did most of the milling on my friend's CNC mill.  For one, it was faster, but mainly because the travel range was actually long enough to cover the entire piece.
My indexable SECO cutter did a good job at this task (which I also won at the Bar Z Bash).
More cutting.  On two sides of each piece, I had to cut through the oxide layer, also known as mill scale, which is harder than the rest of the material due to the way the steel is manufactured.
Blue chips = good chips.  That means all the heat is being carried away by the chips instead of building up on the tool or workpiece.
Once I had the rails squared up, I set the vise on top to make sure it would fit at the width of my machine table.  Looks good!
And then, for a little extra precision, I surface ground the rails together.
Now back on my machine, I could complete the final operations: drilling the mounting holes.  First indicating one rail in my tiny vise (which actually doubles as the lathe compound!).
Then using the edgefinder to locate center.
Drilling holes for the 3/8 socket head screws that mount the rails onto the table.  I'd already made 3/8" T-nuts back in the strap clamp post.
Here using an endmill as a counterbore.  Endmills in a drill chuck are not advised, but for some reason it worked this time, probably because I wasn't side-cutting.
Lastly, chamfering the holes to remove the sharp edges.
I then set the rails up on some 1-2-3 blocks, and bolted them to the table utilizing the new mounting holes.  I drilled and tapped 1/2"-13 holes for mounting the vise.  Notice where I marked the hole locations with blue marker.  I added extra holes to allow bolting the vise in multiple configurations depending how much clamping capacity I need.
Using a combination square to align the rail to the machine table prior to indicating.
After that, the rails were done!  I will admit, it does seem funny to be mounting such a massive vise on a small machine like this, but naturally, why would I want to limit myself?!
Bolted down and ready!

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