Clamping V blocks onto 2-3-4 blocks

I've had to diddle around trying to clamp a V block down onto a 2-3-4 block while keeping said collection square to the spindle
Actual use was drilling for a scope mount on a Stevens Favorite single shot. I left the action on the barrel and used a Kant-Twist clamp (w/poly jaws) to hold the action against an angle plate (keeps the barrel lined up at right angles to the action). But I had to use blocks to raise the v blocks high enough for the tang to clear the table (the tang was actually down in a T slot).
So how can you clamp down v blocks onto 2-3-4 blocks and still remain square to the spindle?
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On Mon, 11 Feb 2008 10:18:49 -0600, Louis Ohland wrote:

Loctite.
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Interesting use of adhesives. How is the residue removed after the machining is complete? Will applying force in shear be enough to free the blocks?
_ wrote:

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On Mon, 11 Feb 2008 10:45:44 -0600, Louis Ohland wrote:

Oh, did you want to be able to take them apart after? (chuckle).
(I corrected your posting error for you.)
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I thought of making some finger clamps to pull down the V block, but that doesn't answer how to keep things square while tightening things down.
_ wrote:

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wrote:

If these are the tapped and drilled blocks, could you use a combination of your finger clamps or custom clamps pulled in by a cap screw in the tapped holes and locating dowels in the untapped holes? There's a clamp on my lathe saddle which looks about right, it has a long tail to the support surface, a short clamping surface, and the one hole for the clamp screw between, inverted of course. Something like that sized to fit in the v block slot and rest its tail on the 2-3-4 block would work if the tapped holes were in an advantageous location.
Then you could indicate the v blocks before and after tightening. I'm assuming that the angle plate keeps the action vertical, and therefore the barrel and the v blocks are square to the Z axis, and could be indicated square to the x axis when clamping to the table. Is the barrel untapered where it rests in the v-blocks? If so, seems like it should work.
Pete Keillor

<snip>
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This barrel was untapered thankfully, or I would have had to of used centers or angles.
Not sure if the 2-3-4 block holes are tapped, but that could be fixed. Perhaps drilling the V blocks for cap screws that would screw into the 2-3-4 block.
Use a "set screw" from the side of the 2-3-4 block to adjust the block before tightening it down. Indicate on the side of the V block to insure that it is lined up.
Pete Keillor wrote:

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Louis Ohland wrote:

Not easily I'd expect since the blocks should be hardened and ground, making tapping them after the fact difficult.
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Mm. Well, thanks for raining on my parade...
If they would be difficult to tap, then I could use bolts to pass through, and T nuts tapped for the bolt size.
Pete C. wrote:

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Could you have taken the slab sided action (assuming) and clamped that into your mill vise and then indicated the barrel to horizontal? Then place a support under where you are drilling?
I have a Stevens miserable loader that I've relined and just need to cut off the barrel and crown. I didn't get grandma's gun so I bought one that needed a bit of work so I'd have one for myself.
Wes
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Interesting, I suppose using brass stock to protect the action from scratches would work. That would keep the action reasonably square to the spindle.
Consider this- indicate the vise so it's 90 degrees to the X axis, put the V blocks up so the barrel is horizontal, tighten the vise so the action is tight.
This would be OK for drilling with no side forces, up next to the action, but milling for a dovetail would make me wonder how rigid it would be without fastening the barrel and V blocks down.
Wes wrote:

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Are you putting both scope mounts and iron sights on it? If so the front dove tail would need support.
I had to think for a while to imagine how a tapered barrel lies in a vee block. My brain told me a line of contact on both side but until I took tapered line up punch and vee blockto verify, I wasn't ready to bet myself money on it.
Can you support the action in the mill vise and then clamp your vee block to an angle plate at the barrel end?
Wes
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Wes wrote:

Dad uses a scope. Eyes aren't good enough for iron.
In this case, the barrel was straight (thank God!) It's a match barrel, and it loves the hell out of Yellow Jackets from Remington. Sorta odd, YJs are not IMHO the classical match ammo in any stretch of the imagination.
Dad simply turned the action 180 and reclamped it to the angle plate to mill out the dovetail for the forearm hanger.

The end of a tapered barrel will touch the sides of a V block at three points at the most, depending on whether the block is square to the table or on a angle plate. On an angle plate, the barrel will touch at each side of the v, along the circumference of the barrel, and at a point on the lower front edge of the muzzle (not exactly, but this is machining, not rocket science).

Sure, you could, but how is one to determine if the bore is parallel to the table?
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In this case the barrel is straight. You could use an indicol and test indicator to tram the side and then top of barrel. A level would get it close enough up and down also for this application.
If you have an edge finder, you can use it to kick off at both ends of barrel until you have the barrel aligned with the table long axis.
If you only have a piece of smooth rod you can clamp in the spindle, use that and feelers to check clearance on side from one extreme to another and then the top. The lenght of that barrel is working in your favor.
Feelers can be paper or whatever you got to work with.
HTH,
Wes
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Well, that does it for a straight barrel. Taper?
Wes wrote:

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I thought about that a bit. I'm embarrassed to admit that indicating a close fitting mandrill or stub sticking out of muzzle is the best I can come up with at the moment. When turning a stub, two separated rings of contact vs the whole lenght in barrel is the way to go.
Wes
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I use these things https://travers.com/htdocs/pdf/0653cat.pdf or a drill press vise to hold Vee blocks in messy setups. The vee block can be raised on an adjustable parallel and the vise can be clamped to the table.
Or make a vee block out of aluminum or such and drill and tap it as necessary for custom setups. I cast mine from scrap hard solder in a wooden mold.
Jim Wilkins
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