My first injection mold and the Rabit HY-4 injection molder

[JAZZCNC]

Well it might be, but there are numerous instances where people ask for information when a simple search reveals everything.

Grow a sense of humour Eddy I was clearly having a Bleedin Joke.!! . . . . . . Clue was at the End. .

[Robin Hewitt]

Well, gavztheouch seems to have left the premises so we will never know if it was bleedin' obvious or whether I should have pointed him at the other one

[gavztheouch]

Cheers Robin, I have seen that site from a previous post you made on another thread. Ebay is also a good place to find parts for molds there are a few chinese sellers selling ejector pins, springs and bushings, I dont have a link but they should be easily viewable.

Thanks for the heads up on purging deisel I was not aware of how toxic some plastics are when burnt or that you should not mix certain plastic together for safety.

The rabit takes molds bases that can be made on the lathe ie. cyclindrical not square, at some point someone has modded the machine to also accept bigger square or rectangle molds. The machine came with a manual with some basic dimensions and mold making tips. I will try and scan some important pages and see if anyone can help me work out how to cut the injector gate on the rear of the mold.

[gavztheouch]

Any ideas on how best to machine this gate entry in the mold, the mold is cylindrical so I can use a lathe.

I can see 4 components to the operation,

1. 1.1mm hole
2. 4mm radius
3. 60 degree bore?
4. 90 degree bore?

[m_c]

CNC lathe would be the simplest.
.
However, with a selection of drills, boring bar, 90deg countersink, and an 8mm radius ballend mill it could be acheived on a manual lathe.

[Robin Hewitt]

Hard to see what is going on, is this where a plasticiser nozzle connects to a mould parting line?

I would not have thought it would be critical if there is no other inlet (insert "beats me, shrug" smiley here)

[gavztheouch]

Robin - This is a diagram of the nozzle/injection entry on the rear of the mold. The 'small internal cone' I think is hot metal cone that keeps the plastic from setting in the entrance to the injector point. Is this what you call a plasticiser?

I think you are right that this is not so critical to get all the angles and rads just so. I think the only critical point would be the depth that the hot cone pokes into the mold specifically the 1.1mm diameter hole that feeds the mold cavitiy. If it goes in too far it will block the mold and if its too far away it might allow the plastic to set?

[mekanik]

If you can get an engraving bit with the 60 deg angle you should be able to do it.
If you go over to http://www.model-engineer.co.uk/ and look up "D" bits this will show you how to make one from silver steel, drill your hole go in with the "D" bit to the required depth then tickle the hole with the engraving bit.
Good Luck
Mike

[Robin Hewitt]

I'm still not understanding what I am looking at.

The plasticiser is the bit that converts granular plastic to melt. This has to connect to the mould, inject the melt, hold the pressure until something freezes, gates, sprue, whatever, disconnect from the mould and melt more granules.

Generally there are 3 ways in to a mould. On the mould parting line, through a sprue bushing, through heated runners where the melt never sets.

I thought that sprue bushing was usually a flat on flat seal with maybe a puff of cold air if stringing got too bad.

I thought I saw something like a countersunk screw head shaped cavity in your picture which would be fine and dandy if it was on the mould parting line because you wouldn't have to worry about getting it all out before the next shot.