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CaptainSlug

Member Since 17 Feb 2006
Offline Last Active Today, 07:49 AM

Posts I've Made

In Topic: Caliburn: Mag-fed Pump-action Springer

Yesterday, 01:46 PM

My first attempt as spincasting was a complete disaster. It produced no parts and made a big mess. I may not have had the two plates clamp together had enough. I also neglected to put the cross-pins into two of the parts. So the entirety of my pour leaks out and onto the area around the drillpress.

 

So my first set of blasters is likely to be made through individual pouring of mold cavities instead of spincasting.

 

The only positive accomplishment is that I threw together a pressure pot out of some junk laying around at work. I can use it to make individual casts that are bubble-free.

rs3_72.jpg


In Topic: Caliburn: Mag-fed Pump-action Springer

19 May 2017 - 03:03 PM

No, that's how all the black parts on the blaster will look. And it's before I've cleaned up the flashing.

 

On Monday I'm putting together a pressure pot which I can use to cure the single-part molds without bubbles. The spin-casting molds won't fit, so those will require baby powder.

 

I have four molds left to make and probably not enough silicone left to pour them all.


In Topic: Caliburn: Mag-fed Pump-action Springer

19 May 2017 - 12:51 PM

Alternative uses for hot plates: Mold pre-heating for tacticool licorice sticks

rs3_71.jpg

This mold worried me for quite a while and it ended up working better than expected. It just needs to be weighted down and covered with polypropylene (or HDPE) while it's curing in order to prevent it from bowing. It also NEEDS mold release. But with those two things addressed I was able to cast it with the full-length through-hole already inside of the finished piece.

 

Larger molds are clearly going to require pre-heating in an oven since their mass prevents even heating from a single side. But if you can get the mold pre-heated evenly, the result is a significant reduction in demold time, and more uniform curing of the part. The downside is that any uneven heating of your mold might distort its shape, so you need to secure it to a backing plate or weight it down while the part is curing.


In Topic: High Cap Magazine Collective Brain-Spew

18 May 2017 - 07:27 PM

His blower should run fine at 3S or 4S. That's pretty much the voltage range of a car battery anyways.


In Topic: Caliburn: Mag-fed Pump-action Springer

18 May 2017 - 12:58 PM

Spincasting mold #3 is sanded and cut and I successfully poured and cured my first two parts.

rs3_70.jpg

Things learned today:

 

1. Product says it has a 30-60 minute demold time. This doesn't hold true for deeper parts as the full cure for the parts is closer to 6 hours. So to reduce stress on the part being removed from those molds, mold-release is vital to prevent part distortion during demolding, which should be done at closer to 2 hours.

2. 1-to-1 by volume sounds easy, but doing it by weight would actually be more convenient since it doesn't require graduated containers or measuring fluid levels. I'm checking the SDS to see if I can just make a weight based ratio and do my pours based on that instead.

3. The finished parts look like they're made out of sugar.

4. When curing the resin creates enough exothermic heat to distort plastic cups. So I have to worry about that being an issue during larger pours. I may want a metal container to pour excess or waste resin into if there's no suitable mold on hand for that.

5. I'm probably going to need a pressure pot eventually.

6. Because of how stretchy the mold material is, I really underestimated how much of an overhang I can accomplish in a single-sided mold. This is good to learn now because it changes what I expect will be feasible with the more complicated molds I still have to make.

7. The mold itself may need to be preheated to 150F. This specific material cures by exothermic reaction, so thinner areas may not be getting hot enough on their own due to decreased volume. So my casting area will need either a toaster oven or a hotplate for mold preheating.