DIY Injection moulding by JR Hartley.

**HankMcSpank** · 02-09-2010

Ok, so I started aquiring 'machinery for the home' about 18 months ago....

DIY CNC machine - check
Mini-lathe- check
PCB fabrication - check
Injection moulding - dammit, I've gots to gets me one of those.

Joking aside, I've now a burning ambition/need/want/blah blah to be able to make my own custom guitar pickup bobbins.

"Why Hank, why - injection moulding is for grown ups?"

Well, because nobody makes them in the size I need ...I presently make them out of acrylic on my CNC *but* even just making one bobbin, I end up with a beard like the guitarist in ZZ Top, so while my last beard was growing my mind began to percolate (never a good thing).

So what are my options...

1. Ask someone to make them for me .....pros - less hassle. cons - massive spondoolies. (for the mould)

2. Ponder how I can make them at home. So my immediate thought was,of "does such a beast exist", well this is 2010 so yes it does....

http://cgi.ebay.co.uk/Bench-Table-To...item35a7cd377f .

but OUCH!

I think I've seen manual ones elsewhere (which clamp to the bench & where the operator is the 'compression element' lol!) ...smaller cost, but still at least one British Kidney in payment.

So I thought I'd throw this one out to the mycncuk 'massive'....what would you recommend?

My requirements are... a plastic bobbin which looks something like this...

http://ww.tinyurl.com/38jq75z (but to my own size - about 5mm long x 5mm high)

Any clever ideas about how I could make them in quantity....or how I could get them made in quantity without having to force my wife to work down Commercial road?

**ecat** · 02-09-2010

No idea about the bobins but here is a DIY Injection Moulding machine :)

http://www.users.uswest.net/~kmaxon/...d_mach_137.htm

**HankMcSpank** · 02-09-2010

Originally Posted by ecat

No idea about the bobins but here is a DIY Injection Moulding machine :)

http://www.users.uswest.net/~kmaxon/...d_mach_137.htm

Intersting link ....but *way* above my skills (or needs).

this manual lever style is perhaps more of my accessibility level...

http://replicatorinc.com/blog/2010/0...ction-molding/

or if someone wants to go the "scrapyard challenge" route...

http://www.youtube.com/watch?v=v8oRzCvGFbw

it does make me wonder if I a standalone 1 axis (Z plane) CNC machine could be designed to do the compression aspect?

**Robin Hewitt** · 02-09-2010

Now there's a subject close to my heart :rofl:

Here's a useful link...

http://www.dms-diemould.co.uk/

I started making an injection moulder because I didn't have room for the real thing in the garage. Then I suddenly got space and bought an old 25 ton Arburg, haven't plumbed it in to the 3 phase yet.

The point being, I have most of a home brew, fully automatic injection moulder about 6 feet behind me. All hydraulic, opens closes, ejects, injects from a hot pot a la Travin, measures plastic in, heaters all wired up with a digital thermostat, plugs in to a paralell port for all the critical timings etc.

I don't really want to sell it, but I can be arsed to finish it. If you are interested I am sure we can come to some arrangement :naughty:

**NB70** · 02-09-2010

Anyone tried DIY iinjection moulding with a glue gun ? I think you can get nylon and polyethylene glue gun rods:

http://www.mutr.co.uk/index.php?cPath=56_19_57

**Jonathan** · 02-09-2010

Aww I'd just finished typing a really long post then the webbrowser crashed :(.
Anyway....take 2

I've seen/used a 'manual' injection moulder at school. It requires a LOT of force to pull the lever to inject the plastic. As in hanging off the lever with my feet off the ground isn't enough (granted I was only about 15 at the time but you get the idea) .... so I'm not sure a Z-axis would be up to it. Then again you do get a huge mechanical advantage with a screw, but is it going to be fast enough? The machine you had a pot which you put the plastic pellets in, waited for it to melt... then squash so quite simple really. I could try and get a picture of it if you like?

I think your main issue might be making the mould. There are only two moulds for the one at school - both made by the teacher. He told me they were difficult and took a long time to make, especially since he used the surface grinder on the mating faces of the two parts. I guess it could be easier to CNC mill the mould, but still something to consider.

I don't mean to put you off, just thinking aloud that's all!

R.E. Bobbin making.
Couldn't you just cut them out of a sheet and use a T-slot cutter to do the undercutting? That way you could machine the lot in one go.....and tessellate lots onto a sheet of plastic.

**Tom** · 02-09-2010

Another little teaser here... :)

http://www.cambam.co.uk/forum/index.php?topic=355.0

**John S** · 02-09-2010

Which Commercial road ?

.

**i2i** · 02-09-2010

funny you should mention a desktop stand alone plastic injection machine, i have the very same thing.

**HankMcSpank** · 02-09-2010

Originally Posted by Robin Hewitt

Now there's a subject close to my heart :rofl:
Here's a useful link...
http://www.dms-diemould.co.uk/
I started making an injection moulder because I didn't have room for the real thing in the garage. Then I suddenly got space and bought an old 25 ton Arburg, haven't plumbed it in to the 3 phase yet.
The point being, I have most of a home brew, fully automatic injection moulder about 6 feet behind me. All hydraulic, opens closes, ejects, injects from a hot pot a la Travin, measures plastic in, heaters all wired up with a digital thermostat, plugs in to a paralell port for all the critical timings etc.
I don't really want to sell it, but I can be arsed to finish it. If you are interested I am sure we can come to some arrangement :naughty:

Thanks for the mould mft link - Have you had a quote from them for a mould?
Your injection mould - being 3 phase would be a problem (I'm low-fi here!)...I'm also envisagening an unfeasibly large contraption!?

Originally Posted by Jonathan

I think your main issue might be making the mould. There are only two moulds for the one at school - both made by the teacher. He told me they were difficult and took a long time to make, especially since he used the surface grinder on the mating faces of the two parts. I guess it could be easier to CNC mill the mould, but still something to consider.

I guess most people aspire to a nicely finished mould (so no machine marks are visible on the end result) - but since these puppies will not be visible, I could probably accept a rough & ready one! I'm hearing that Aluminium loaded expoxy might be the route for the mould for my modest requirements.

Originally Posted by Jonathan

R.E. Bobbin making.
Couldn't you just cut them out of a sheet and use a T-slot cutter to do the undercutting? That way you could machine the lot in one go.....and tessellate lots onto a sheet of plastic

That's a reasonable idea...I might ponder. It'd certainly make the beard a little bit shorter (more Rolf Harris than ZZ Top), but I'd still prefer unshaven (I'm talking beards here - right?). Also, a quick skeg on the net shows they might be a bit hard to find? (ok, so Argios probably isn't the best! -joke ok!). BTW that second link - he rocks, talk about understated....legend!

Originally Posted by John S

Which Commercial road ?.

C'mon, You know the one (psst: you never heard of tipping?)

PS Not related to injection moulding at all, *but* hot off the press tonight - another 'machine for the home', after much trashing of plastic & flaying of switches & sensors - a 'direct to copper clad board' inkjet printer :-)

Edit: Just seen your post...

Originally Posted by i2i

funny you should mention a desktop stand alone plastic injection machine, i have the very same thing.

We need more details than that - a photo to prove it along with a scan of your driving license etc. Seriously...I need more details - I think I now need the opposite to viagra (flacidagra?)