Subject: Re: Injection molding at home suggestions.

From: "Frank J. Mihm" <[email-masked]>
Date: Sat, 11 May 1996 16:00:10 GMT

[email-masked](James I. Lewis) wrote:
In <[email-masked]> [email-masked] (Damon
Brantley) writes: 
>
>I apologize ahead of time, if this is a little off topic.
>
>I have some small parts that I would like to try injection molding.
>I was thinking about trying to use a hot melt gun, but substituting 
>some half inch plastic rod for the hot melt sticks.
>
>Has anyone else tried this before or recommend a type of plastic that 
>I could try this idea out on. I have thought about casting resin, but 
>the resin is expensive and seems rather messy to work with.
>
>Thanks in advance for any suggestions.

Damon --

James I. Lewis said that there was an article in Home Shop Machinist about injection 
molding.

There is an index to "Home Shop Machinist" and "Projects in Metal" magazines  at:

        ftp://plains.uwyo.edu/metal/hsmpimix.txt

It covers 1982-1994.

I did a search there for "injection" and came across the following citations which 
might be of interest:

Plastic Injection Molding Machine Parts 1-4     
HANSON, RODNEY W.       
HSM 91 M/J 16 J/A 32 S/O 44 N/D 32

Plastics Forum, The Parts 1-3   
SELTER, PAUL E, Sr.     
HSM 86 M/A 44 J/A 42 N/D 36

Plastics Forum, The Parts 4-5   
SELTER, PAUL E., SR.    
HSM 87 J/F 48, M/A 34

Enjoy!

                        Frank

---

From: [email-masked] (James Kirkpatrick)
Date: 12 May 96 23:18:18 MDT

|>Gee I don't have a HSM index handy but there was an artical a couple
|>years ago about a plastic injection machine.

Try http://plains/uwyo.edu/~metal for an index.

Searching for injection.
  
   Note: HSM=Home Shop Machinist, PiM=Projects in Metal,
   MN=Margin Notes in PiM, M&M=Metals & More in PiM.
  
Title:  Plastic Injection Molding Machine Parts 1-4
Author: HANSON, RODNEY W.
Issue:  HSM 91 M/J 16 J/A 32 S/O 44 N/D 32
  
End of search.

This is also in the Village Press book "Projects 5" --

Searching for injection.
  
   Note: ProX=Projects #X from HSM, MetX=Metalworking#X from Pim,
         WRX=The Shop Wisdom of Rudy Kouhoupt,
         WFM=The Shop Wisdom of Frank McLean,
         WPD=The Shop Wisdom of Phillip Duclos
  
Title:  Plastic Injection Molding Machine  Pt 1-4
Author: Hanson, Rodney W.
Issue:  Pro5;193;
  
End of search.

---

From: [email-masked] (Glen Goens)
Date: 12 May 1996 23:18:47 -0400

Damon Brantley ([email-masked]) wrote:
:        I apologize ahead of time, if this is a little off topic.
:         I have some small parts that I would like to try injection molding.
:         I was thinking about trying to use a hot melt gun, but substituting 
: some half inch plastic rod for the hot melt sticks.
:         Has anyone else tried this before or recommend a type of plastic that 
: I could try this idea out on. 
:         I have thought about casting resin, but the resin is expensive and 
: seems rather messy to work with.
:         Thanks in advance for any suggestions.

I tried a few experiments along these lines once.  The biggest problem I
had was that the plastic melted slower than the glue sticks and had to be
forced through the gun with a pointed stick.  The plastic that I experimented
with was taken from the lids of plastic milk jugs, it's very similar to the
plastic that Mattel used in their toy injection molder back in the 60's.
For best results you should make a bracket to hold the glue gun and rig
a lever to help force the plastic through the gun.

If you want to experiment with casting resin, go to the local auto parts
shop and look for "clear resin for fiberglass".  This stuff should cost
about 8$ a can and comes with a small tube of hardener, it yields a hard
somewhat brittle piece.  If you need a softer, tougher piece, get a can
of body putty and mix it 50/50 with the clear resin and use the hardener
>from  the body putty.  The nice thing about this is that you can always
use the leftovers to patch the old Jalopy ;-).

Out of curiosity, how do you plan to make your molds for this project ??

Glenn Goens -- [email-masked]

---

From: [email-masked] (Edward Haas)
Date: 13 May 1996 08:35:16 -0700

Glen Goens ([email-masked]) wrote:
: plastic that Mattel used in their toy injection molder back in the 60's.
: For best results you should make a bracket to hold the glue gun and rig
: a lever to help force the plastic through the gun.
	--OBTW, if you can find one of the Mattel injection molders at a 
garage sale, hang on to it! That same basic unit is still sold, new, in 
an industrial version: I saw one at WESTEC this year, with a price tag of 
around $8,000 or so... With luck you might find an original for $20 at a 
flea market...
-- 
	"Steamboat Ed" Haas	:	What would happen if.....
	COMING SOON		:	Bagpipes grew like vegetables??
	http://www.west.net/~steamer  	
		---Decks a-wash in a sea of words---

---

From: Mike Rehmus <[email-masked]>
Date: 14 May 1996 12:20:38 GMT

HSM had an article on building a table-top injection molding machine.
They recommended strips of milk carton.  Didn't look too practical
but guess it can be done.

I don't have the issue(s) in which the project was published, just
one of the composite books that Joe Rice publishes from time-to-time.

Best regards,

Mike Rehmus

---

From: [email-masked] (Jon Gellman)
Date: Tue, 14 May 1996 21:18:52 GMT

>>Thanks in advance for any suggestions.

There are some excellent new urethane casting resins that I find
really terific for small parts. One is Synair's Pour a Cast 2, a 2
part low viscosity ivory colored resin that gels in 3 minutes and
demolds in 15. Its also measured by volume, 1:1. I believe the price
is $22 for a 2 quart kit. For extra strength I place glass mat or
strands in the mold before pouring. With products like these it hardly
pays to bother with the extra effort to make injectable molds even if
you have the equipment. Lots of industries are turning to these resins
for short runs and/or short time production.