Subject: Re:Injection molding at home suggestions.

From: [email-masked] (Damon Brantley)
Date: Tue, 14 May 96 07:10:00 GMT

Thanks for all the responses so far. My news server is extremely slow  
at getting responses back so I have to look at Dejanews and AltaVista for 
responses. Thus I am answering questions in a nonthreaded manner that some 
have asked and some of my results so far.
        First, the type of hot melt gun I am using has is a trigger type 
instead of the thumb push type.However, since the plastic is harder than the 
glue, you can't get much of a grip with the trigger.However, I may be able to 
apply some type of liquid rubber material like Plasti Dip to the part the 
grips the plastic stick to get some traction.
       In the case of PVC, the glue gun does not get hot enough to melt the 
plastic. Also, need good ventilation as the PVC seems to emit some 
odor. Someone can probably tell me or warn me what it is.  I also noticed this 
when cutting PVC with the lathe. I am going to try and get some nylon to 
experiment with.
        To remedy the temperature problem I am going to cannibilize a 
soldering iron (25W Radio Shack hobbyist iron) and using it as the heating 
element. A quick and dirty test, just holding the iron against the glue 
(plastic) chamber yielded some melting, but I do not think I was making very 
good contact.  I will also have to machine an adapter so that the element will 
fit. (This is starting to turn into a project all its own now! : ) I hope I do 
not get the iron too hot or I may melt the handle!. Will also have to be 
careful not to get the plastic sticks too hot also. Will see what happens.
        One response I received, said that when in a melted state, plastic is 
still too viscous to force through the nozzle of a hot melt gun. I guess I 
will see for myself. Worst comes to worst, I can alway use my arbor press. 
(Oh boy, another adapter to make!)
        Another question was about how am I making the molds. I have never 
done this before. The simplest part is about 1 inch long with a diameter of .1 
inches for 1/2 inch and .25 for 1/2 inch. I hope to be able to just drill 
holes in some metal rod and fill the void with plastic.(More like casting 
here)  After the plastic is cooled, I will have a pin in the end to eject it. 
(Using either a hammer or arbor press) Whether I will get a plastic part back 
or a hole filled with plastic, I do not know. Depends on how well the plastic 
sticks to the metal. Hopefully, the shrinkage of the plastic as it cools will 
keep the part from sticking inside the mold. 
        If that does not work I will drill the holes and mill two halves for a 
split mold.
        The other part part is tubular. Depending how the above goes, witll 
determine how I do the tubular part. I will omit the details for now.
        I will also check into getting the book from village press that has 
the injection molding articles from HSM. Also broke down and finally ordered a 
subscription to HSM and PIM.
        Hopefully, this weekend I will get a chance to try all this. I will 
keep you all posted if there is interest.

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From: [email-masked]
Date: Wed, 15 May 1996 12:15:07 GMT

On Tue, 14 May 96 07:10:00 GMT, [email-masked] (Damon Brantley)

>keep you all posted if there is interest.
this bad stuff i work in a plant that uses 60 injection molding
machines. pvc along with some of the other plastics is very dangerous
if over heated. we've been told by health officials that one wiff of
it an it's goodbye! if you're going to play with it, be sure to vent
well as you may not be able to control temp. accurately enough.
thought i'd just throw my 2cents worth in.