Re: home made injection mold

I also have one of those Gingery Plastic Injection moulding ,machine. I
built mine like the book says. It works great but I would redesign to make
it much simpler. I ended up using every machoine in my well equiped shop ie
lathe , mill, grinder, drill press, bandsaw, welder, torch, air compressor.
I would use three pieces of 3/8 thick angle about 4X4 and ~12L
each angle would be drill near the ends for a 5/8 running stud.
Seperator/spacers would be used between the angles and nuts used to secure
this " press type arrangement" A acme 5 TPI screw would be used to drive the
injection piston with a bearing so the rotary leascrew doneesn't twist the
piston rod. The chanber would be bored for a .001 clearance with the piston.
A large hole would be cut into the side of the block for loading larger
amounts of plastic. This way only a few tools would be required..
I have scanned a picture of the unit from the book if you are interested.
BTW I nearly have all the parts to build the vacuum forming machine also.
Dan
-----Original Message-----
From: Joe Vicars <jvicars@...>
To: CAD_CAM_EDM_DRO@onelist.com <CAD_CAM_EDM_DRO@onelist.com>
Date: Thursday, February 03, 2000 7:27 AM
Subject: [CAD_CAM_EDM_DRO] home made injection mold

>From: Joe Vicars <jvicars@...>
>
>Well....
> This project was the start of my huge interest in the world of CNC,

and mechatronics in general. Even though the project

>itself didn't involve controls of any kind, it gave me the confidence and

desire to reach for more and more sophisticate home

>projects.
> While working for a major appliance manufacturer, I was a design

engineer on a team for a new refrigerator. I was

>surprised and appalled at the prices of aluminum prototype tooling

(injection molds). For instance, a mold for a knob or some

>other simple shape was in the range of 6k to 10k bucks! Remember, these

are aluminum tools for prototype parts. They don't

>have to have fancy ejector setups, no cooling lines, and most of all, no

strict constraints on surface finish, parting lines, or

>flash.
> So during a lunch time discussion with some fellow co-workers, someone

whipped out one of their parts that cost 12K to

>prototype. I said, "holy crap, I could build that at home!" Well, since I

was in a group largely composed of magna cum laude

>"engineers" they all burst out laughing and the general consensus was,

"yea right". (everyone's finger making little circles

>around their ears)
> As I am sure everyone on this list will understand, my personal ability

to make "things" is a source of great pride and

>therefore could never let this assault on my personal dignity go

unchallenged.

> So I built the mold, then I built a little "machine", cut up some old

milk jugs and shot the part. Most of you will be

>disappointed with the relative lack of sophistication of the injection

molding machine. I got the most satisfaction from the

>mold itself.
> The mold was machined by hand, manually, with an aluminum base and brass

dropouts. The molding machine was made from a block

>of steel, an oven thermometer, an arbor press, and 2, 400 Watt cartridge

heaters. So that I don't delude you into thinking that

>I thought all this stuff up myself, the majority of my ideas came from a

book called (strangely enough) "how to build an

>injection molding machine", by a guy named Gingery. Some of you may know

the source, Lindsay Books www.lindsaybks.com They

>publish old and out of print "how to" books that are like buried treasure

for tinkerers.

> Since I was pressed for time, I skipped the use of any type of

thermostatic controls on the heater block. I simply switched

>on the heaters and when the block got to about 350F I switched them off.

(this took a little practice to control burning). The

>milk jug material was clear polystyrene that shot well around 350-400F. I

won't mention that all my parts ended up smelling

>like burnt plastic, but the damn thing worked, and I sure showed those guys

(they couldn't have cared less). But I did

>accomplish what I said I would do, and I feel like I proved my point. I

quit the big giant corporate world right around the

>time that finished the mold. I have since gone to work for a 3 man group

without all the B.S. and no stress (for less money of

>course)
> Anyway, the total cost of the project was about 20 bucks for two

cartridge heaters and a thermometer. Of course I already

>had all the aluminum and such lying around. Time wise I build the mold in

one weekend and the molding machine the following

>week after work. Not a bad amount of work for 12 grand!
> I will take pictures and go through the do's and don'ts and "what I

would do different" for those of you who care. Anyone

>who want's more detail let me know.
> Sorry about the length.
>
>
>Matt Shaver wrote:
>
>> From: "Matt Shaver" <mshaver@...>
>>
>> > From: Joe Vicars <jvicars@...>
>> >
>> > I built a home made injection molding machine and mold one time on

a

>> bet. It's an interesting story if anyone cares.....
>>
>> We care, WE CARE! How did you do the heating and temperature control?

What

>> did it look like?
>>
>> Matt
>>
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>Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the

discussion of shop built systems in the above catagories.

>To Unsubscribe, read archives, change to or from digest.
>Go to: http://www.onelist.com/isregistered.cgi
>Log on, and you will go to Member Center, and you can make changes there.
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