turbocad's custom dual/quad headlight mod

Status
Not open for further replies.
A perfect vacuum of 0 is only going to be acheived in sapce...

It was just a reference point for the example.

---------- Post added at 08:45 AM ---------- Previous post was at 08:09 AM ----------

Max vacuum at sea level is 29.92in Hg =14.69533223463184lbs per sq in.

I used 15lbs per sq in to make the math easier. Its close enough for the example.

---------- Post added at 06:42 PM ---------- Previous post was at 06:25 PM ----------

Yeah, what MTN said. :tongue:

I was just trying to give John a quick and dirty indicator test to see if his current set-up would work.

In terms of the pressure exerted on the inside of the pot, it sounds a lot worse than it is. True, the pot could catastrophically implode, but it's much more likely to do what we call, "leak before burst". Meaning, it will crack, slightly deform or fail at a seal and never get to that "implosion".

First, isn't the possibility of a catastrophic implosion enough to warrant extra precautions?
Second, with the ISS stuff you deal with parts and materials that are very precisely engineered for the task at hand. (I used to be in structural engineering and worked on multiple SLC (Space Launch Command) projects in Cape Canaveral and Vandenburg AFB) We are talking about a pot made to cook spaghetti here, not a purpose built chamber. You cant speculate with any kind of real accuracy what it will do under what MIGHT be an incredible amount of force relative to its intended use.


The reality is that this current set-up should work for the purposes John is looking for. Even the food vacuum sealers don't suck nearly as much pressure as this one is capable of, but would probably work for setting these reflectors. You just need a differential so that the air wants to move from high pressure to low pressure. A perfect vacuum is not possible, but it's not necessary either.

Didn't turbo say he needs to pull 29"?

---------- Post added at 06:46 PM ---------- Previous post was at 06:42 PM ----------

...... who's taking bets as to weather the gas line crushed or not? :tonguey:


I'm betting that you were careful and did not pull enough to collapse the hose.
 
Last edited:
ok, been in the garage tonight working with this again & even pouring a new mold, everything works awesome... if I can believe the mightygauge I'm using at the moment then I'm pulling a little over 30"Hg, :tonguey: obviously this gauge isn't very accurate. the other day I ordered a good thrmistor type electronic digital gauge & sensor that reads down to 10 microns. measuring in microns I will be able to see even tiny changes & it should also be very accurate, just to really satisfy my curiosity & to be able to see it continue to pull down even further when it's at full vacuum & see exactly what I'm really hitting...

the gas line did not collapse, this line is pretty strong & really reminds me of the other vacuum stainless hoses that I've seen which is why I thought it might work so I bought it & it def does work well. the pot did not implode & everything just works fine, no leaks at all & even after I turn the pump off the whole system holds vacuum indefinitely, gasket & everything is fine, this pump really sucks, I hit full 30"Hg on my gauge in a little under 40 seconds...

I then mixed up a batch of resin & tried it out... mixed it up well until it was almost milky white from all the aeration & bubbles, then put it in the chamber & started pulling, funny that at ~25" of vacuum I get very little action, just slightly foams up a little. it isn't till I get over 28" that I start to see results, & the real results kick in when it hits the 29" & higher mark. I really think that if I only hit 27 or even 28 this might not work so well or even at all, at under 29 it foams up but just stays foamed up & stays static like that, doesn't really boil & purge bubbles or anything, but when I hit the 30 mark the resin foams up to the point of really overflowing the bucket that contains it unless I close the valve & regulate it manually... hold a bit, then burp it by releasing the vacuum then vacuum again, repeat as necessary rise & fall until it extracts enough air that I can maintain full vacuum with the foam risen without boiling over & let it continue under full high vacuum boiling & boiling until it settles back down close to the actual fluid level & stops boiling & very little action left, then it's done. it is still foamed up looking a little at that point but when I release the vacuum it drops down & it's just crystal clear. it really works nice even on this very thick viscosity resin.

I then tried a pour of this degassed resin in a modified mold that I prepped but still no go, I opened up the flow paths in this mold while waiting for the chamber to be done & thought it might fill but finally tried it again last night & it still only fills the mold half way. this resin is very thick, almost like molasses... at least now with the vacuum chamber though I can build a new mold with the better tin cure silicone & try to get it to work better than this existing mold so I started pouring that tonight. too late for pictures but I'll put some up tomorrow.

so far the chamber is a success. I did another test to see how well this works. water boils at 212deg F at sea level at normal atmospheric pressure, but the lower the atmosphere the lower the boiling point of water... at somewhere over 29" of vacuum water can boil at even room temperature & below. I had to try it out to see if it really was pulling this much vacuum so I put a bucket of cold water in, this is in my garage where it maybe hit 50 deg F if that, probably in the mid 40's or so really, it was very cold last night... well in about 30 seconds or so the cold water was boiling up a storm so violently that it was even splashing on the lid :laugh:

tonight I had a container that was rinsed out with water & it was still wet with many droplets of water all over so I put it in the chamber under vacuum for ~5 minutes & it completely dried up every drop of water without a trace... this thing is pretty cool... pictures tommorow...
 
I had little doubt it would work. The materials you used might not have been designed for the application, but based on the materials & thickness used (according to the mfg website) they were more than adequate. I certainly can speculate with ballpark accuracy based on experience and knowledge of materials. The chance for catastrophic failure is VERY low. I only said true because even a .0001 chance still makes it true. Pressure vessels almost always leak before burst when made of metal for vacuum. Same is not true for positive pressure. Don't mean to go too far off topic, just continuing on with the recent discussion.

I was interested to hear about the pressure(s) at which you got action. The viscosity/density of the resin determines that and I was surprised you needed as much as 29". Keeping the resin under vacuum should really slow down the curing process, so I wonder if holding it at a lower vacuum for a longer time period would actually work. No matter since you have what you need. Just interesting from a practical standpoint.

After the air was out, did you release the vacuum to help with cure time?
 
Your projects never cease to amaze me glad everything worked out.If you continue to have problems with filling the mold maybe a vacuum assist would pull the resin through?
 
That's so awesome. The pot thing still freaks me out, but hey if it works it works.
:tup:

this pot is commercial cookware & is over 5mm thick. it seems very sturdy & strong. when I was looking for a stainless steel pot in like macy's it's rediculous how thin most of them are, I was able to actually dent most of them with just my finger, so I decided to try this one & it worked out fine...

I was interested to hear about the pressure(s) at which you got action. The viscosity/density of the resin determines that and I was surprised you needed as much as 29". Keeping the resin under vacuum should really slow down the curing process, so I wonder if holding it at a lower vacuum for a longer time period would actually work. No matter since you have what you need. Just interesting from a practical standpoint.

After the air was out, did you release the vacuum to help with cure time?

I'll put more info to show & answer this in a bit. I didn't know that under vacuum the cure is inhibited. this is a good thing because I was afraid that while I was degassing I was also running out of pot life for the material... I did of course release the vacuum after because the material was not in the vessel it would be cured in anyway, so I had to remove & pour it anyway before curing

thats great you got it working.
is the pump loud when running? just make sure you check the oil every so often.
great job and cant wait for pics and you ideas on the CF

the pump is very quiet, just a slight humm & it gurgles a little intermitanty until it reaches full vacuum. I will change the oil soon & flush it out a few times since I don't know how it was treated prior to my use. actually when I bought this pump I also sourced a supplier for a rebuilding kit just in case I needed it, but thankfully it performs great as-is so far...

We should call John "the Pot King"! :rofl:

dude, I already have SO many guys PM'ing me for all kinds of stuff, you give me a name like that & I can only imagine the PM requests I'd get then :bandit: :tonguey:

Your projects never cease to amaze me glad everything worked out.If you continue to have problems with filling the mold maybe a vacuum assist would pull the resin through?

that was my first thought as well, but then lance reminded me that this may also pull the "walls" of the mold in too, which it would & which would be bad, the reflector itself is maybe 1-2mm thick at it's thinnest point & if it pulled in even a little the reflector would be too thin & have holes, I had this problem in the past just by clamping the mold too tight. gotta be forced in with pressure instead of sucked through for this reason...

some pictures in a bit :smile:
 
ok, a few shots



jumbo, this is the viscosity of the silicone I'm using for the mold making. this stuff is no where near as thick as the resin, but it's still not thin either...

1


at 25-26" I get very little action, it foams slightly on top but does not really rise much & doesn't do much at all, just stays slightly foamed with very little outgassing:
1


by the time I hit ~28 it rises slightly more & start to see a little action, but nothing significant really, if I just held it here I don't think it'd outgas completely at all, if it did it would take forever, notice that it hasn't even rised high enough to cover that inner dome, & it was held here a while for me to get the shot....
1


now here it is hitting ~29", & now I'm getting some real action, I have to regulate it to not overflow, but at this poiint it's now outgassing well... remember that this silicone is quite a bit thinner than the resin, which does even less than this when under the 29" mark...
1



it's at over 30" here...

1
 
Last edited:
Right on man, No black hole! No worries, the stock pot vacuum chamber has been time tested in our product development labs :) Looking forward to seeing the pour pics.....
 
heres a few shots of the new resin, after vacuum & cured... it's as clear as glass...



1



1


this is looking right through the bottom of this... clear as glass:

1
 
Last edited:
OK, heres the new mold, i redesigned it yet again from what I've learned from my past attempts... the new silicone I'm using is really nice, & with the vacuum chamber now I get no bubbles at all at the facets of the reflectors, finally got a perfect print & a perfect mold... the new reflectors should be sweet & clear as glass & very sharp reflector facets...



I'm now using a flat rigid base instead of my previous method, makes the mold more precise & aids in sealing the mold. also trying to make it smaller to consume less of these very $$$ materials to make the mold...

1

I'm using a container now instead of building a shell for it, this container is from take-out from my local Japanese restaurant, was for sushi, now for reflectors:tongue:

1


I hot glued the seem & poured...

1



and the results from this morning... perfect print, much better than anything I've gotten up until now, the vacuum chamber is a must for these processes & these materials...

1



1
 
tonight I will pour the top of the mold... I've been in my garage from ~8pm till 3am past several days+ with this stuff, really want to just get these OUT!!! is there a light at the end of the tunnel? maybe... I think I now see a hint of light... last obstical I see now is injecting the mold... getting there I think...



heres a close up of the gauge as a reference for the previous posts if you can't see the #'s so well in the previous pics:
1
 
Last edited:
Incroyable! I think you would make an incredible chef too if you tried. I'd watch your cooking shows.. oh wait, or a show about your projects. Good work!!!
 
Status
Not open for further replies.
Back
Top