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Cheap draw plate


#1

I recently purchased some tank fittings on Amazon. That was the least
expensive way to go, especially if I could get free shipping. In
order to get the additional purchases needed to meet the free
shipping threshold, I ordered a $12 triangular draw plate. It was a
piece of crap (no surprise). I returned it and decided to try and
make my own, since I only need one size of triangular wire. I can’t
find anything on line that describes how to make a draw plate. I was
thinking of using an old file. I can soften it to do the drilling and
filing needed and then harden it again. So far I haven’t been able to
soften it enough to even dent it with a drill. Any suggestions are
appreciated. Thanks. Rob

Rob Meixner


#2

You don’t anneal (soften) ferrous metal the same way as the
non-ferrous (copper, silver, gold, etc). You have to heat to to red
hot then allow it to cool VERY slowly - one way is to wrap it in a
thick layer of fireproof insulation. The traditional way was to heat
it in the fire and leave it to cool overnight as the fire burned
itself out.

Regards, Gary Wooding


#3

Hi Rob,

This is a gloss of a conversation I had with one of my tutors in
London, years ago, but the basic way to make non-round drawplates is
to make a tapered punch of the cross section you need. Triangle in
this case. Make a loooooooong tapered triangle section out of tool
steel rod, and harden it to about RC40, or about brownish purple. If
the punch ends up being longer than about 4", make two. A skinny one
for the first holes, and a fatter one for the larger holes. If you
try to do the whole thing in one punch, it’ll fold.

Get a tool steel plate. Anneal it if it isn’t already. (heat to red,
and let cool very slowly. Exactly bass ackwards from how you treat
precious metals.)

Mark out your hole locations, and drill a series of holes that get
slightly bigger every time. But don’t drill them anywhere near ‘full
size’ for the profile. The smallest one should just get the tip of
the shaped punch through the plate. Then get bigger from there.

Heat the plate to bright red in a forge. Take it out, and set it
flat on top of the pritchel hole of your anvil. (the little round
hole near the Hardy hole.) Use a hammer, and drive the triangular
punch into the first hole in the plate. The goal here is to use the
triangular punch to force the hole to become triangular. As soon as
it’s driven home, and the hole is triangular, flip the whole thing
over, stuff the remaining end of the punch down through the hardy
hole, and smack the small end of the punch to knock it back out of
the hole before the heat of the red-hot plate fries it. (It will fry
it a bit, but it should hold up long enough.) Now you just keep
repeating this step in the next holes, driving the punch a little
deeper each time. (which is why you wanted slightly bigger holes.)
Reheat as needed. Hotter is better than colder.

Once you’ve opened up as many holes as you need, or your punch can
stand, then set the plate back in the forge, shut it down, and let
the plate cool with the forge, so that it’s as soft as it’s going to
get.

then you get to come back and open up the holes. Once it’s cold,
take a flex-shaft, and add a slight chamfer to the wide side of each
profiled hole, so that there’s a sort of funnel leading into the
hole.

Then go around to the back side, and open out the back side of the
profile a bit, so that the point of maximum compression isn’t quite
on the back of the plate. My memory is that you want the tightest
spot about 2/3 of the way through the material, so open up the back
a smidge. (Like the lead-in chamfer, but not as big, and not quite
as angled.) This is the stage at which you can fine-tune the steps
between the hole sizes, if you’re really that nuts. Get an
escapement file, and get in there and tweak the cross section at the
area of minimum opening.

(Take a look at how big round drawplates are profiled, if you want
to see what it looks like. Or a big square, if you happen to have
access to one.)

Once that’s done, then you get to harden it. Reheat the whole thing
in the forge until it’s nice and red (non-magnetic) then quench in
oil or water, whichever your material requires. (Not all steels like
water, and some don’t like oil. Check to see what you have first.)
If you’re buying, get O-1, and quench in olive oil. (If you don’t
know how to keep olive oil from catching fire when you do that,
think hard about whether or not you want to be doing this.) One
trick: pack the holes in the plate with Ivory hand soap. There’s at
least a chance that’ll keep the interiors of the holes from
oxidizing, which will aid in cleanup later.

Then you get to temper it. If you really know what you’re doing, you
can do this with a torch, but for a big flat plate like this, I’d
rather use a kiln. Set it for 450-480F, (239-250C) or so, and chuck
the blank in there for an hour. If you clean one of the flat sides
with sandpaper first, you should see a sort of dark straw or
brownish color.

If you set for 445F (229C) it’ll be a light straw, and tougher, but
more prone to breakage. Your call. Traditionally, they’re tempered
very hard, so down around 400F. Which is why drawplates break so
easily.

THEN after that’s all done, you get to go back into it one last
time with fine grit sandpaper (like 800-1000 grit) and very
carefully polish the area of minimum size, so that the wire has a
good polish on it as it’s drawn.

As you’re doing this, contemplate just why it is that profiled
drawplates are SO much more expensive than round ones. (Which can
be done by machine, pretty much.) Now you know.

FWIW,
Brian


#4

Brian. Thanks for the step by step. I am already working on the
punch, but have not yet learned the basics of working with ferrous
metals. You have filled in a lot of the blanks. I like to make my
own tools, but also like to make jewelry. It is a constant fight for
my time. This time of year I try to clean and reorganize my shop
making the little tweaks that I think about when I am just making
jewelry. It is interesting to see where things settle when you don’t
put them back into their proper place. This makes me think that their
proper place needs to be changed and I do a lot of that this time of
year. Biggest change is that my draw bench was constantly in the way.
It was 8 feet long. I cut it down to 6 feet and built a slide out
shelf for it just under one of my benches. It can be easily pulled
out to use and then pushed back out of the way when not in use. If
anyone is interested, I will post pictures. I would like to do the
same to the rolling mill, but it is a big heavy Durston and I don’t
want it to be at all tippy. I will post more on any progress with the
draw plate. Stay tuned. Thanks again. Rob

Rob Meixner


#5

if you can find a factory that makes leaf springs for trailers and
sweet talk them into giving you a scrap/offcut of un heat treated
tool steel, it will be machineable. Then if they toss it in with
their next batch of trailer or car springs to heat treat it it will
be nice and hard.


#6

Hi Rob,

I use cobalt tipped drill bits to drill steel. It doesn’t need to be
annealed to be drilled. The high speed steel just won’t cut it. I was
able to find them at a tool shop for machinists, but you can find
them on-line as well.

Jean Marie DeSpiegler