I'm new -can I please find out how to make my own draw
plate?
Sure thing.
The 1st thing to consider is what you plan to draw with your
home brew draw plate.
If you’re planning to draw wire, your probably better of buy a
commercially made plate. Some of the import plates for round wire
are available for about $20.00.
The basic premise in considering what material to make the plate
from is; ‘How hard is the material to be drawn?’. Obviously, the
material the plate is made from must be harder than the material
to be drawn. Even though chain & tubing are made from relatively
hard material, their shapes make it possible to change the size
or shape with relative ease.
The next consideration is what is the shape of the finished
product to be (round, square, triangular, etc.). If it’s other
than round it’ll probably be less expensive to buy a commercial
product.
Along with shape, an important question is; ‘What’s the maximum
& minimum size that will be drawn?’. The larger the size range,
the stronger the draw plate material needs to be.
Another consideration is; ‘How accurate does the finished size
need to be?’. If it’s got to be very accurate (+/- .010 in)
commercial is probably more economical.
Now, with those thoughts in mind lets look at some material to
use for draw plates
Most commercially made draw plates for drawing wire are made
from steel. The better ones are made from tool steel & are
hardened. Some draw plates have carbide or diamond inserts the
wire is drawn through.
For drawing chain & tubing (thin walled) draw plates can be made
from steel, hardwood or the harder plastics that have an high
melting point. If made from wood, the wood used should be a
dense, fine grain wood, e.g. maple. If plastic is used, use one
that has a high melting point. The friction & compression that
occurs during drawing causes heat & we don’t want the draw plate
melt or the holes to change size. Corian is one plastic that
fills these requirements. Corian is available from home centers
& shops that make kitchen & bath counter tops. Ask for the
cutouts from sinks, They may be available at low cost or free.
Now let’s consider the design of the draw platre. How many holes
is it to have? What’s the largest size hole? The size of the
holes should not change too much from larger to smaller. If the
hole size changes to much, it will be difficult to pull the item
being drawn through the plate. At the larger sizes the size
reduction can be greater than at the smaller sizes. The entry to
each hole should taper slightly to facilitate the size
reduction. There should be sufficient space between the holes so
the draw plate is strong enough not to break (pull apart or snap)
when it’s being used. A rule of thumb is to leave a space equal
to the hole diameter around the hole, e.g. for a 1/2 hole, there
should be no hole closer than 1/2 in to its edge. The next
problem to consider in making a draw plate is the tools used to
make it. Most plastics & all woods can be machined with wood
workers (sharp) tools. A hand or table saw can be used to cut
the blank that will be used to make the draw plate.
For a round hole draw plate, a good size reduction can be made
using the drills in a standard 29 bit fractional drill set, 1/16
-1/2" in 1/64 " steps. If larger holes are required, larger bits
are available. If smaller holes are required, a numbered drill
set (#1 - #80) will provide the required sizes.
Draw a design of the draw plate before starting. Lay out 3 or 4
lines across the long dimension. The should be separated from the
edge of the droplet & the next line by a distance equal 1.5 times
the diameter of the largest hole. (Ex. largest hole 1/2 in., top
line should be 3/4 in. from the edge of the droplet & the 2nd
line should be 3/4 in. below the 1st line.) The remaining lines
should be spaced based on the largest hole that will be in that
line. For convenience in holding the draw plate while drawing,
leave a 1/2 in border around the entire field of holes.
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When the design is finished, lay out the design on the
material to be used.
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Cut the blank to size.
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Use a drill press to drill each hole, changing bits after
each hole. All the holes should be drilled perpendicular to the
draw plate. If the holes aren’t perpendicular the item will want
to curve when it’s drawn. It’s best to start drilling with the
smallest hole. That way if you forget & drill 2 holes instead of
1, you haven’t created a problem that’s un-correctable.
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After all the holes are drilled, use a countersink to taper
each hole slightly. Counter sink each hole to approximately the
same depth.
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Remove any rough edges. The holes should be relatively
smooth, i.e. no burrs etc. in the holes or on the edges. Any
burrs etc. will leave a scratch the length of the item being
drawn.
When drawing anything, clamping a piece of cloth soaked with a
lubricant, (oil of wintergreen, dishwashing detergent, etc.) so
it contacts the item on the input side of the droplet will make
the draw a little easier.
If you want to make other than a round hole draw plate, You can
start with round holes & then do a lot of filing with needle
files.
Dave