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Flat patterns with rolling mill


#1

I have finally started to experiment with the rolling mill today and
came out with some fabulous patterns on sterling and copper sheet.

Here is the problem. When I dap the circle to make one half of a
bead, the pattern gets flat and is not as prominent as it was
originally.

How do I keep the crispness of the pattern while working with the
pattern whether or not I dap it or manipulate it.

Thank you very much.
Laurie


#2

Congratulations on your roller printing! There are endless
possibilities with that technique. I assume that the dapped beads you
are producing are formed in a steel or possibly brass dapping block
pushed in by a rounded dapping punch made of steel as well. The
solution is quite simple. Dap your roller printed discs into a die
surface composed of a material softer than the disc. Soft pine works
quite well in a pinch. Start by creating a depression in the wood by
driving the punch into the board( the end grain of a large piece o
lumber works well) then drive your blank into the wood repeatedly.
You may need to dig it out with pointed tool occasionally and don’t
forget to anneal as forming progresses. There are of course
commercially made wooden dapping punches and blocks but any wooden
die will scar with repeated use if you are forming heavier gauge
metal capable of taking a deep roller print. Lead blocks or cakes
used to be used for such work and could be recast when they became so
scarred as to be unusable. It was always necessary to carefully clean
any work formed with a lead block to prevent contamination of the
work which would sabotage the project during subsequent annealing or
soldering. It would probably by desirable to avoid lead in your
studio altogether considering its potential toxicity. The good news
is there is available a viable alternative, Low temperature melting
thermoplastic. This stuff melts between 140 F and the boiling point
of water. It’s moldable, verily putty in your hands. Setters use it
to support work while stone setting by embedding the piece to be set
in it. After allowing it to return to room temperature and harden the
piece may be clamped in a vise for further work without fear of
damage. Plastic can both hold and support the piece against quite a
bit of pressure.

To use this stuff for your purposes (dapping) I 'd assemble a couple
of tuna cans or short containers and fill them up with thermoplastic
pellets close to the top edge. You may wish to cut down the side of
the containers so they require less material to fill. Then put just
the thermoplastic into a Pyrex bowl filled with water and microwave
till the plastic begins to melt (2 min. in mine).Using a hot pad
remove the bowl from the microwave and with an old metal spoon or
similar instrument remove the gooey thermoplastic pellets from the
water. Allow them to drain on a metal surface a few moments and after
carefully determining that the plastic is cool enough to touch, kneed
the remaining water out of the thermoplastic mass. Stuff that plastic
into your container ; mash the top level and then insert the dap(s)
of your choice halfway into the plastic creating matching
hemispheres. Remove the dapping punch and allow the plastic to fully
return to room temperature before use. This technique can be used to
make shapes other than hemispheres as well. When your dapping
depression becomes scared reheat the die in boiling water and make a
new depression!

Low temperature thermoplastic is sold to the trade under various
names. One well known brand is called Jett Set. Jet Set comes in two
flavors, with a ceramic additive and without. I prefer the flavor
without ceramic for dapping. It has a slightly waxier surface
allowing the metal being formed to slip a bit in the depression ( on
the down side it scars a bit easier but that’s easily rectified). GRS
Tools distributes a brand called Thermoloc to vendors and I’m sure
there are other brands out there as well. MY dentist uses a medical
grade of this stuff to take quick impressions for crowns!

Michael Edwards
Flying M Designs


#3

Laurie,

How do I keep the crispness of the pattern while working with the
pattern whether or not I dap it or manipulate it. 

You will almost always get some degredation of the pattern when you
form the sheet metal, especially if it’s shaping in a way that
requires the surface of the sheet to seriously stretch or compress.
Dapping into a hemisphere is a good deal more difficult than simply
bending. Plus, if you’re dapping the metal with a steel dapping punch
into a steel (or even brass) dapping die, then the surface of the die
is contacting your pattern. You might as well planish your pattern
with a hammer, what with the forces that steel die puts on the
pattern.

The way to preserve at least a good deal of the pattern (and some
delicate textures just won’t be preserved so well no matter what) is
to use a surface to form into, which is softer than the metal. Wood
is one that works to a degree, though it can mark softer metals, and
dapping into a lead block is another traditional method (though you
have to be very careful to clean the metal carefully, so there’s no
trace of lead sticking to it, before any heating, soldering, etc.
Some plastics can be made into gentle dapping dies as well.

Perhaps the best way to do this is by hydraulic die forming (funny
thing, that’s been a recent topic here on Orchid). With this, you put
your metal on top of a piece of urathane rubber, itself contained in
a boxlike contaner so it cannot spread out laterally. The pattern
faces the rubber. Now your press (if you have one ) can press the
dapping tool smoothly down into the metals’ back. No impact, this is
high pressure, but in it’s own way, rather gentle. Urethane rubber
is interesting stuff. Somewhat soft, but it cannot be compressed. So
when you press something down into it, the rubber must flow and
displace somewhere, and what it does is to essentially try to flow up
and around the intruding form, which it does with considerable
pressure. So as the dap presses down on the metal and into the
rubber, the rubber presses the sides of the metal up and around the
dap. This will not be as easy to get a full 180 degree hemisphere,
as the edges especially will not want to go that last little bit.
Great for lentil shaped beads, less so for full spheres, but it can
be done. You can also use the press like this using firmer dies,
again still made of something that won’t mark the metal, like delrin,
etc.

he downside to this type of forming is that it require rather high
pressures, and this usually requires some form of actual press. The
hydraulic presses like the Bonney Doon or others similar to it, use
20 ton or higher bottle jacks to generate thise pressures. That’s a
good deal more than you get with a hammer, and though you can form
into urethane somewhat by hand with a hammer, etc, it’s limited. To
get fully dapped hemispheres, you’d need a press. So then there is
another piece of equipment to add to your wish list.

Hope that helps.
Peter Rowe


#4

Hi Laurie,

I use a piece of thin leather in the block, and lightly tap the disk
into the form. You can also use soft wood and make an impression
with the dapping tool first, and then follow up with the same
technique.

Mark


#5
How do I keep the crispness of the pattern while working with the
pattern whether or not I dap it or manipulate it. 

As others have suggested, you can use a press and a urethane pad.
For more on this, Susan Kingsley’s book, “Hydraulic Die
Forming for Jewelers & Metalsmiths” is worth reading. Rio Grande
carries it.

You do not need a 20 ton hydraulic press, especially to get started.
For small things a 1 ton arbor press might be good enough. (Search
the Harbor Freight website to see an example of an arbor press.) I
started with their 1 ton and upgraded to a 2 ton arbor press. It is
so effective I find it unnecessary to use my 20 ton shop press most
of the time. I use a 2 foot length of pipe to extend the press handle
and increase the force I can apply without having to strain myself.

It may be a bit hard to locate a 2 ton arbor press at a reasonable
price. I got mine for $95 at a farm and ranch supply retailer. It
looks just like the one on Harbor Freight’s website, just a lot
bigger. It weighs close to 100 lbs.

Best wishes,
Neil A.


#6

If you’re losing the pattern, try lining the dapping block with
something soft like leather or rubber. If you are making very small
beads, you might need a soft plastic that you can dap into shape, so
that it fits the cavities perfectly; remember that each dapping
cavity would be smaller after you did this.

Jamie
http://primitive.ganoksin.com


#7

HI,

To try and keep the parameters simple, IF the flattening and
degeneration of crispness in your patterns is caused by stretching
that occurs during dapping (Or similar operations), there isn’t much
you can do to prevent that. You can minimize it some by dapping into
soft materials-- urethane pads, pitch, tree stump, etc.) instead of a
steel dapping block, but it doesn’t sound like that is your exact
problem, whereas stretching does sound like the culprit. You could
make the pattern deeper, so that when it thins and spreads out from
stretching, there’s more of it’s detail left than before, but other
thatn that, nothing pops into mind.

http://www.sheltech.net (work)


#8

To dap without losing the texture I cut out a disc of buckskin to
line the depression in the dapping block. Works fine. The more you
round it however, the more you distort the surface and consequently
the pattern.

Jerry in Kodiak