In article D8kVa.43601$zy.7079@fed1read06,
larsen-tools wrote:
wrote in message
.. .
Hi,
I have to make some loooong threaded rod and need a die-head. Anyone
have one for sale or suggest where I might find one? I got sticker
shock at MSC. g
Why not buy long threaded rod?
It comes in 10 foot lengths.
Agreed! I've got some, but I have uses for them, and got them
by haunting eBay for a while. And as I use them (on a bed turret),
there is a limitation of about four inches before the end of the
workpiece would hit the vertical rod which runs through the center of the
turret for clamping it during the cuts.
If you mount it in a quick-change boring bar holder, you could
probably do it, but there are other problems:
1) How far will the carriage travel before it has to stop? It
will open the chasers and stop cutting at that point. (How does
this compare to the needed length of the threaded workpiece?)
Any attempt to unclamp the workpiece and re-start the cut after
repositioning will probably generate problems, though you
*might* be able to close the chasers onto an already cut area.
2) How will you feed the carriage?
If by threading feed, there is a chance for a slight error
between the leadscrew feed and the thread pitch being cut by the
die chasers, which can either pull the die head ahead enough to
trip the release.
Or -- there is the possibility that the feed will be faster than
the thread, in which case you will have excess force which will
probably damage the threads being cut.
If you are feeding the carriage by hand, there is a better
chance of things working, as you can keep up with the feed by
feel.
3) How are you supporting the workpiece which has already passed
through the die head? If it is truly long, you will need a
steady rest beyond the die head to keep it from whipping (unless
you are running *very* slow.) And the fingers of the steady
rest will probably damage the already cut threads.
Long threaded rod is usually made in production by *rolling* the
threads, not cutting it, and I'm not sure what the lathe is like to
allow such long rods.
As long as the needed thread is a standard one, and the rod
doesn't need any other features (bearing points and such), commercial
rod is probably the better choice. Even Home Depot has 24" and 36"
all-thread available. If you need it longer than that, you'll have to
find an industrial supplier somewhere, I think. But if you need it
longer than that, it would also be a serious pain to do on a lathe, with
or without a Geometric die head.
Perhaps some more details -- length, diameter, and thread form
(e.g. standard V threads or Acme or something else), would give people
more of a starting point for advice. Also, some information as to how
big a lathe you're working with, and what other tools. You *can* do the
job within reasonable length limits with a single-point cutter, a live
center in the tailstock to support the free end, and a follower rest to
support the workpiece very close to where the cutting is being done.
Geometric die heads *can* be found from time to time on eBay --
but they may not do just what you need, so it would be good to be sure
that one would serve your needs before purchasing one -- even if you
luck into one in good condition for $300.00 or so. (Price is also a
function of the diameter of the workpiece. Mine are 5/16", 1/2" (rare),
9/16", and 3/4", and after you get that, you still probably have to
purchase a set of chasers for the thread you intend to make. The odds
are against your eBay find having just the right chasers in good
condition. And a set of chasers will go for something between perhaps
$70.00 (for ones for the 5/16" die head) up through $140.00 (for the
3/4" die head). These prices can go up or down depending on whether you
hit Grand Tool during a clearance sale, or whether you have to order a
special that your vendor does not normally carry.
Good Luck,
DoN.
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