Home Made Injection Machine

[Rob_M.]

I was wondering about some of these DIY Injection molding machine books I've seen on Ebay. Anyone have any insight on these or maybe have made one. I'm considering making one anyone have any insight.

thanks,
Rob

[Klean-Power]

yes I bought one of those books.
It seems pretty good but I may double the size as it can
only handle 2oz of plastic.
It will cost about 400 bucks to build. not bad.
As someone who knows a bit about plastics I think its a
good deal.

my opinion
Hope it helps

Tony

[vacpress]

I purchased and read the Gingery book... http://www.lindsaybks.com/dgjp/djgbk/index.html

These are neat, old fashioned how-to books.. Sort of like John Kleinbauers plans(YES i bought some... 3 or 4 years ago.. I like them. They are funny)


Anyways! The machine described in the book is interesting and looks easy to build.. Could be built cheap if you happen to work around alot of angle iron.. I read it, and then fatasized about using the general design, but using cartridge heaters and pneumatic cylinders and other odds and ends off ebay to make a pretty nice benchtop injection molding machine for around $1,000.00

I may do it one day.. The drawings are around here somewhere.. But, I definiately recomend the Gingery book. Its fun and interesting and only around $15.00. I am not sure you will want to build the machine described, but it will be of interest if you want a DIY machine-shop aproach to building a demonstration IJ machine.

Note: Check out the site. They have lots of books, and on amazon there are some pages, including, i think, a page with a diagram of the whole machine.

Cheeers

[leberen]

I bought a Jiffy Shot sample injection molder off ebay thinking it could be used with plastics. Turns out you're only "supposed" to use it with their proprietary blue stuff for "testing molds" I have other plans. This model has 2 handles which can be attached to pneumatics and mounted to a base. The nozzle can be exchanged im guessing if using for plastics dosent work. The shot size im guessing is much larger than 2 oz. The beautiful thing is it wont inject until the nozzle is pushed down!!! it uses around 65 to 70 psi, ive only used mine to clear the blue stuff out but it works. theres one on ebay right now, and its as cheap as if ya built your own:http://cgi.ebay.com/Jiffy-Shot-Mold-...QQcmdZViewItem

does anyone know the consequences of using ordinary plastics in this unit? IE dripping or cloggin?

[vacpress]

$450 dosent seem 'cheap as if you built your own'

if you have the proper tools, you could make a pretty neat injection unit with ebay crtridge heaters, a piece of steel rod, ebay pneumatic items(cylinder, solenoid valve, regulators, etc)...

[DJPLAST]

Plastic pellets can react very violently under pressure and excessive heat, do you know what these pressures and heat thresholds are? If not, steer clear of messing around with these "chemicals". Being spattered with 400+ deg of sticky plastic will leave a mark! Have 30 + years as moldmaker/molder, you must always respect the high heats and pressures involved, they WILL react with no warning!!

[leberen]

Djplast, I understand these are some warnings I had read about a while back, as the "Blue" wax has certain properties that are supposed to keep it within the DME Jiffy Shot (and not all over the floor or in one's eyes) a more dense plastic should be retained as easily as the wax's properties do?

The "home brew" Injection molder assembly schematics were available on ebay, I happened to buy one before my purchase of the Jiffy. The folks at www.hobbyinjectionmold.com sold them, and the completed machines. Not just anyone should actually build these things. I have chosen the DME because the only difference it has (other than holding more plastic than home brew) is the all in one package. AND www.hobbyinjectionmold.com stopped making home brews because of potential lawsuits, no longer a registered domain!

I picked the jiffy for a lot less than the one in the link I posted earlier. Its just for example of whats available, and similar machines are or were up for grabs on ebay for around $320-450.

[miljnor]

Plastic pellets can react very violently under pressure and excessive heat, do you know what these pressures and heat thresholds are? If not, steer clear of messing around with these "chemicals". Being spattered with 400+ deg of sticky plastic will leave a mark! Have 30 + years as moldmaker/molder, you must always respect the high heats and pressures involved, they WILL react with no warning!!

If you work with this Molds something a little more constructive would be helpfull.

Mills and lathes are just as dangerous as IJ machines, but more information on the danger is common knowledge. So they seam less dangerous.

A general warning to someone who is researching a project is usually uneeded as thats one reason they are researching. But what IS NEEDED is information on how to SAFELY do this are where to get this information.

So if you have good info... Give it up man!

[DJPLAST]

Miljnor, sorry to come across as negative, just wanted to make a point of the dangers involved with this type of experimentation. These plastic chemicals are the basis of plastic explosives, they can be deadly, even in small quantities. The gases that can build up in a barrel (on a molding machine) can blow hoppers through the roof, and even crack the barrel with a 1" thick wall. I have personally witnessed the latter, not a pretty sight! Just be extremely careful.
My suggestion is to stay with a local molder to do your molding.

[Geof]

Originally Posted by DJPLAST ......These plastic chemicals are the basis of plastic explosives,......

This is an exaggeration that is chemically inaccurate. Plastic explosives are a class of compounds which contain the element nitrogen in a form of chemical bond known as a nitrate bond with oxygen atoms or as an azide bond which is between multiple nitrogen atoms; these chemicals bonds are unstable and can react explosively. Many of the thermoplastics used for injection molding do not even have nitrogen atoms in their chemical make up and those that do have the nitrogen in totally different forms of chemical bonds which are stable and non-reactive.

This is not to say that the temperatures and pressures used in injection molding are not dangerous; they are. Overheated thermoplastics can de-polymerize and form flammable and/or toxic gases which can under the correct conditions explode. But this is not any different to the explosion hazard of propane gas or natural gas. The pressures and mechanical forces used in injection molding are comparable to those in heavy duty hydraulic systems and require similar attention to correct and safe procedures.

Using exaggeration and inaccurate analogies to dramatise dangers is not helpful. Sometimes it can be counterproductive because an inexperienced person does not have sufficient knowledge to know what is an exaggeration and what is not. When they discover that part of a warning is indeed exaggerated the tendency is to discount the whole warning including the parts that are reliable. There was a fable written many generations ago about the dangers of 'crying wolf' too often.

[miljnor]

And "Stay with you local molder to do your molding" roughly translates to don't do any molding for a DIY'er because this is a hobby for alot of folks and spending 20k on a mold is just a little outside most peoples pocket books.

So personaly I would ignore your "suggestion" and being since I read as much as possible and try to know the dangers inherent in anything I do. I will proceed as I do on all things knowing that everything is dangerous to the uninformed and ignorant.

[leberen]

Well, as Ive expressed my thoughts earlier that its difficult for a individual or group to sell books that help others possibly harm themselves. So, the guy that ran the above mentioned website before it was closed down mentioned melting legos and YOU CAN TELL THAT PLASTIC IS TOO HOT, based on the color of smoke emitted. Correct me if i'm wrong but isn't it grey or white? So a good temperature should be around what for melting for example, legos? Answering these two questions should clarify some confusion here and get some gears crankin.

My suggestion, Keep an eagle's eye on ebay for "plastic injection mold," "plastic mold machine," and the like. I came across 3 or 4 machines within the 350 to 500 range, even a larger what I would call medium scale machine. that one went for nearly 800 if I can remember.

I'd like to make an all electric machine using ac motor, power steering pump to move hydraulic cylinder and a PLC to controll sensors of various locations. too occupied at the moment.