Firm grip on round rod in vise without scarring

I need to thread some aluminum rod. The mini lathe is really not up to the task. I threaded some with it the other day just to prove I could, but
anything I can do with a die will be a lot faster to just do by hand. I was thinking of taking a block of aluminum and drilling a hole the diameter of the rod for a snug slip fit. Then mill a groove/slot in the side of the block to the drilled hole. Slide in the rod, and put the whole thing in the bench vise. Any problem with that scenario? I keep plywood blocks cut to fit the vise, but they don't always get a good enough grip on rod stock.
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Clamp two bits of wood together, drill a hole slightly smaller that the rod at the junction of the two bits of wood.
Throw this in the bench vice with the rod in the hole provided, I'd think that'd hold the bar no problems. Then again I am a bit rough sometimes.....
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Improvement on that:
Clamp two blocks of steel, aluminum or very hard wood together *with a piece of cardboard between them*. (cereal box, not corrugated) Then drill a hole down through the cardboard *the same size* as your round workpiece. Same size hole gives you good surface contact for maximum grip. Undersized hole is likely to mar your Al rod. Cardboard assures the blocks will grab the workpiece before they hit each other.
If you want to get fancy, use two pieces of 1"x2" steel/Al stock on edge, drill several sizes of holes (who knows what size you'll need next time) and put in a couple of guide pins between the blocks so they hang together as a unit with the half-holes aligned. Add flanges at the top so the dingus hangs in your vise and you don't need 3 hands to position tool and workpiece and close vise. Good for heading up ad hoc rivets from round stock, too.
--
Mike Spencer Nova Scotia, Canada

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On Tue, 5 Jul 2011 19:49:28 -0700, "Bob La Londe"

Line them with thick buffalo hide leather. And if you do the same diameter often, make half-round vise liners instead of the vees. They'll grip more area at a time.
-- Fear not those who argue but those who dodge. -- Marie Ebner von Eschenbach
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Bore a hole the same size as the rod in a block of Aluminum. Sawcut through the center, either all the way through, so you have 2 pieces, or just a slot to allow it to squeeze the rod. Bob will then be your father's brother.
I've also split a suitable nut from a corner of the hex with a hacksaw when I needed something to clamp a threaded piece in the vise. It clamps well and doesn't damage the threads.
Pete
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Pete Snell
Department of Physics
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On Tue, 05 Jul 2011 19:49:28 -0700, Bob La Londe wrote:

Tap with a die on your lathe, unpowered. Use the tailstock to locate the die perpendicular to the work, use the chuck to hold the work, don't ever turn the motor on.
Works a treat, and you don't have to waste time eyeballing the thing to get the die perpendicular, nor do you waste work due to impatience with same.
--
Tim Wescott
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On Tuesday, July 5, 2011 7:49:28 PM UTC-7, Bob La Londe wrote:

So, don't you want to chuck the rod in your battery drill/driver and aim it at your die, with the die held in the vise? A pin vise, or a three-jaw chuck, is intended to hold a cylinder, might not need any softjaw construction on your part.
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    May I suggest that the block be some other metal than aluminum. Working the same metal with two surfaces together can result in galling (pressure welding and pull out transferring metal from one side to another, resulting in a pitted and rough pair of surfaces.
    Of course -- aluminum threads better with a thread rolling die, but that will need something larger and more powerful than your mini lathe. The rolled threads are smoother and stronger.
    Good Luck,         DoN.
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wrote:

Isn't that only going to happen if it slips?
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    [ ... ]

    Actually -- one of the primary places where it happens is two aluminum gears meshing with significant torque applied. The teeth should (if properly shaped) only roll on each other, not slip (or very minimal slip). Yet the cycle of pressure causes the galling.
    Stainless steel against stainless steel does the same. That is why you will normally see dissimilar metals used for gears in contact with each other. Aluminum, brass/bronze, steel, stainless steel -- all depending on what is needed.
    Enjoy,         DoN.
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Try applying some powdered rosin: http://www.mansionathletics.com/hot-glove-rosin-bag-rosin-bag-roz-b-baseball-bat-grips-and-rosin.html?channelid=Google%20Products
Oak blocks cut from old pallets etc work well.
jsw
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