Hi Kamil:
Basically there are two ways to set up for subgates. one of which won't work for you because you don't have a full CNC sinker.
The way that will work for you requires you to tilt the workpiece up into the proper plane so the ram will follow the axis of the subgate.
Small inserts can go into a vise, bigger ones onto a sine plate.
Picking up the location is pretty simple.
Tilt the block and clock it in parallel to the X axis.
If you are using something like a Rotobore (spins the electrode and is HIGHLY recommended) you can center a pin of a known diameter, touch the edge of the cavity with the side of the pin, add one radius and then add the amount you need to to get the axis of the gate located the proper amount from the edge of the cavity.
You can calculate this with trigonometry, or you can do as ADFToolmaker recommends (and I do too) you can lay it out in a simple 2D CAD program and just interrogate it.
If you do it in CAD, it will simplify your life to lay it out with the block tilted and the electrode axis vertical, exactly as it will be when the parts are in the machine.
Trust me on this; it will save you grief, especially when the angle is close to 45 degrees and it becomes confusing whether you laid it out correctly and is not obvious to visual inspection.
If you are not using a Rotobore, make or select a pin that has the same body diameter as the pin from which your electrodes are made, stick it in the vee block first to find your subgate axis location, then substitute your electrode to pick up the height.
A note on subgate electrodes and subgates in general.
I am a very strong believer in ball ended subgate electrodes sized correctly and burned just deep enough that the tip of the ball penetrates enough to make a round gate orifice of the correct diameter.
If the ball tipped trode penetrates just the right amount, the shearing edge at the top of the gate will be a straight line (the ball has penetrated to it's equator at the top of the gate) and the bottom will be a bit like a ski jump when seen in cross section.
There are big advantages to doing it this way:
1) It's easy to balance the gates on a multi cavity mold...just burn until a target sized gauge pin will pass through the gate... you can get them to match within tenths this way easily, because the orifice is round, not elliptical so you can check it with a gauge pin.
2) It's easy to pick up the zero height of the trode...just drop it in Z until it touches the angled parting face and call that point Z-zero.
Subsequent trodes are picked up the same way.
3) it burns WAY better than a pointed trode because the tip is robust and doesn't evaporate as soon as you put power to it.
Also you can get some flushing down it and it won't break off and arc in the burn.
4) The "ski jump" redirects the plastic flow right at the gate orifice and the cosmetic appearance is typically much better because the plastic cannot jet as easily.
For those of you unfamiliar with jetting, it happens when a small gate opens out directly into a big cavity...the plastic squirts into the cavity without touching the cavity sidewalls until there's enough plastic to provide a backstop to force the plastic out into the sidewalls and slow down the flow.
This leaves a snaky looking cosmetic blemish and a structural weakness in the part.
5) the gate is MUCH easier to shear as the pins push it, (because the cross section is round, and the bottom has an acute angle relative to the part sidewall and will break as the top shears) so the mold doesn't run as dirty and the gates last longer before the knife edge is abraded away by the plastic.
6) it's easier to make the trodes (assuming you have a CNC lathe) because you don't have to turn or grind them to a super fragile dead sharp point.
So that's it in a nutshell; pretty easy once you wrap your head around setting it up.
Cheers
Marcus
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