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Purchasing vacuum wax injector


#1

Hi

I am thinking about purchasing a vacuum wax injector for production
casting in the very near future. The main reason I am considering
this is because some of the designs that I plan to put into
production are similar in dimension to dog tags i.e. (wide and flat
approx. 40 mm by 20 mm by 1.5 mm with a raised border and lettering).

I am currently using a small wax injector and I am having problems
with incomplete fills on the lettering.

I was wondering if anyone on the forum is familiar with vacuum wax
injectors like the one that Rio Grande sells.

I would also appreciate some advice on injecting wide flat pieces.
Generally I cut vents into my molds and use westcast aqua injection
wax. I am pretty happy with the results I get on most of the pieces
I’m working with, it is just the flat waxes that seem to be a
problem. Thanks in advance.

Ted Curtis


#2

Dear Ted,

Call me Friday and I’ll tell you everything you ever wanted to know
about Vacuum wax injectors. Central standard time 651-227-3921. It’s
not just the injector for injecting the type of part you describe.

Best Regards,
Todd Hawkinson


#3
I would also appreciate some advice on injecting wide flat pieces.

I’m not a casting expert, but since you’re already dealing with Rio,
I’d suggest trying their Buckle wax before you buy a new injector. It
is intended for lightweight, thin pieces. The part number is
700-212/5 for the 5lb package. Substitute /50 for the 50lb package.

James in SoFl


#4

Hello Ted

I inject moulds of a similar size to the one that is giving you
trouble. Here are a couple of things that I have learned.

Wax too hot is as much trouble as wax too cool. The very fluid wax
appears to not have enough density to push the air out into the
vents. Try starting with a cold injector and inject the molds as it
warms up. This will give you are variety of samples of temperature
and you might find one that is better. Although not always a good
idea, you can try using a dusting of talcum powder for these molds.
Work the talc into the vents. Blow away any excess. The talc will
hold the vents open a little and allow air to pass through them
better.

If the mold is cold the wax will cool too quickly on the surface of
the rubber and not fill completely. Try warming the mold a little.
I do this by setting a cloth on top of the wax injector and then the
mold on top of it. Do not let it get hot, that is harmful to the
rubber. Do get it noticeably warmer than room temperature.

Increase the air pressure that you use for this mold. I will often
use about 12 lb of pressure.

Different waxes of course will behave differently and you way want
to try a wax for filigree type of models.

I have overcome the problem that you are experiencing by using all
of the above and am happily using my 25 year old injector.

Good luck
Franklin


#5

Ted

I can’t help on the vacuum wax injector but flat objects maybe. I
always got a sort of concave effect when injecting flat (say coin
like) objects and figured it was my clamping pressure deforming the
mould. I couldn’t reduce clampimg pressure to a point that
eliminated the dishing without horrible flashing of wax out of the
side of the mould (and the odd hot hand!).

As an experiment I applied narrow strips of thick adhesive tape
around the edge of my mould on both sides (that is top and bottom to
allow clamping pressure at the edges where I wanted it but not in the
middle where I didn’t) and vastly improved my waxes.

Got to be cheaper than a new injector!
Cheers
Andy Parker, Agate House Lapidary
Ulverston, Cumbria, England
@Andy_Parker
www.agatehouse.co.uk
Tel: 01229 584023