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level head
05-17-2006, 10:22 PM
i need a 4 foot piece of 1/2 acme threaded rod .
I dont want to order a 4 foot long piece
Were can buy a die of this size..
does anyone have one for sale

thanks

wierdscience
05-17-2006, 10:55 PM
I haven't seen actual dies like those that fit in a diestock,I have seen a few hex dies used for cleaning acme threads in things like valve stems.

If you had a Geometric type die head for your lathe you could buy a set of 1/2-10 chasers to fit it,but threading it would still be fun.

Just out of curiosity,why don't want to order a readily availible section of all-thread rod?

tattoomike68
05-17-2006, 10:59 PM
A die head with the chasers would cost enough to buy one hell of a lot of threaded stock, You better need much more than 4 feet.

Mike Burdick
05-17-2006, 11:40 PM
Level Head,

I am under the impression you are making a CNC mill, so my suggestion is based on that.

If getting the 1/2-inch precision acme threaded rod is difficult, have you thought about using 1/2-inch 20 TPI (National Fine) all threaded rod? This will allow you to continue on your project. Then when you finish it, and are satisfied with its performance, you can replace it with the more expensive precision 10 TPI acme screw. This way you won't have a big expense during the 'development' stage. To be honest with you, if your CNC mill turns out well, you'll probably want to use ball screws instead.

level head
05-17-2006, 11:43 PM
but wont the fine treaded rod take a while to move the axis on the mill

Mike Burdick
05-17-2006, 11:47 PM
Level Head,

If you want the same speed as the acme rod you suggested, use 3/4-10 (NC) all threaded rod. I chose the 1/2 20TPI because it matches the physical size you want as a final screw. Sure it'll go half the speed of design but you can easily program around that. My suggestion is a way to make your 'Prototype' from stock products. Using the 1/2 20TPI would allow your final CNC mill to be made with the minimum amount of machining changes when made to your final design parameters.

J Tiers
05-18-2006, 12:16 AM
I strongly doubt that any die would run to a true enough advance to be of any use at all. You'd probably get something like 9.97 TPI or 10.04 TPI on average, not 10 tpi, over a long distance.

Just enough error to be really annoying, and probably a variable error to boot.

The threaded rod is likely no better, but at least you know you are just trying it out. There are places to get good acme rod reasonably. Search the back posts both here and at Practical Machinist and you should find them.

Evan
05-18-2006, 01:36 AM
I bought 1/2 x 10 acme precision leadscrew stock from http://www.keystonethreaded.com/

They are pleasant to deal with and it cost about $1.00 per foot for rolled thread stock in 4140 heat treated steel in 3' lengths. They have a $50 minimum so I bought some bronze acme nuts to go with it. They had no problem with sending it by US postal service which eliminates the brokerage problems since all you have to pay is the standard Canada customs clearing fee of $5.00 cdn. Don't forget that for normal travel when cranked by hand it needs to be left hand thread.

John Stevenson
05-18-2006, 03:37 AM
Don't forget that for normal travel when cranked by hand it needs to be left hand thread.

That depends on where the nut is fastened in relationship to the handle assemble.

If the handle assembly is fixed to the apron and the moving nut on the slide then yes it needs to be LH

However if the handle assembly is on the slide and the nut is fixed to the apron then it needs to be RH.

The secret to getting it right is moving nut, LH, fixed nut, RH.

Southbends, clausings etc LH, Myfords RH.

.