Domo Caps [working thread]

[Batmann]

great job Domo
and thanks for those links.
I watched most of these videos few months back but pressure pots here in France are crazy expensive and Harbour freight  didn't answer my multiple requests.
I believe that once you have all the tooling you can produce high quality custom caps.
I'll follow this thread closely 

[Binge]

Yo....that pyro head looks incredible. IT'S SO SMOOTH!

I really hope his casts come out as smooth

[domoaligato]

Yo....that pyro head looks incredible. IT'S SO SMOOTH!

I really hope his casts come out as smooth

+1

[domoaligato]

I think I found a site like ours for resin casting
http://www.resinaddict.com/forum/index.php

our site is the holy grail of keyboard info
there's is the holy grail of resin casting!

[mkawa]

strong tints made me look twice....

and I was expecting to see one of these 

(Attachment Link)

but looking forward to see what awesome keyboard science will happen here 

me too and want!!!

anyway this looks like low pressure molding. my understanding is that casting happens at atm. it's just a terminology thing though. i think it's about time that we have a good thread on thermosets and molding. the only thing i would change is to use this super awesome quiet compressor instead of the HF one: http://www.amazon.com/GMC-SYCLONE-Ultra-Oil-Free-Compressor/dp/B0038MWDXY/ref=sr_1_1?ie=UTF8&qid=1375999813&sr=8-1&keywords=quiet+compressor

you really don't need much vacuum, frankly, so it should be plenty sufficient. the HF compressors mostly work but oh my crap they are loud.

[mkawa]

that gasmask master looks great btw. also, something to think about is wax sprues.

[domoaligato]

I have been lurking that resinaddict site all afternoon and it is a back and forth between to vacuum or not to vacuum. but they all use pressure pots.

It looks like that is a must....

thanks for the link mkawa!

[domoaligato]

that gasmask master looks great btw. also, something to think about is wax sprues.

I am going to try toothpicks like this guy....

[rurushu]

wow domoaligato, your pyro (not sure the name, never played TF2) keycap is awesome!!!!

[domoaligato]

I have made a harbor freight pressure pot and I have poured my mould.
It should be ready tomorrow to start casting.

[MOZ]

Excited!

[domoaligato]

So I poured/injected my first cast about 6 hours ago.... To be continued....

[domoaligato]

oh and for people wondering exactly what shore hardness is other then the diagram on the last page...

http://www.astm.org/Standards/D2240.htm

[bueller]

So I poured/injected my first cast about 6 hours ago.... To be continued....

Yeah baby, we want more hot resin injections!!!

[Binge]

Domo.  I've been looking into vacuum systems to degas rubbers/plastics.  Have you found anything on allowing the plastics to cure in a mold under a vacuum?

[Tarzan]

Domo.  I've been looking into vacuum systems to degas rubbers/plastics.  Have you found anything on allowing the plastics to cure in a mold under a vacuum?

Not to step on Domo's response, but the videos I've watched all seem to show vacuum being used to degas the molds (sometimes the resin itself), and then the actual casting is done under pressure.

There is a process for vacuum casting, to draw materials into a complex mold, but I haven't seen much information on those options.

The Guerrilla guide to CNC machining, mold making, and resin casting recommends using a vacuum chamber for most casting work, and only suggests a pressure chamber in some cases - rather the reverse of the home casting videos I've seen.

http://lcamtuf.coredump.cx/gcnc/ch4/  (How do you link a URL to text, again?)

4.2.1. Vacuum pump and chamber

Insufficient mixing may cause a range of problems with finished parts - but vigorous stirring will almost always introduce some air into the resin. This problem aside, bubbles of air may get trapped inside mold crevices as you pour the mixture in - even if your mixing skills are beyond reproach. Last but not least, some resins may simply liberate some amount of dissolved gases once the polymerization reaction begins; IE-3075 is an example of that. Vacuum degassing solves all these problems, and is not as scary as it may sound.

4.2.5. Optional: pressure pot

There are some complex, multi-part molds where it may be hard to consistently avoid air entrapment, even with the aid of vacuum; on top of that, there are some resins that tend to be difficult to fully degas, or that will develop bubbles of carbon dioxide when not mixed perfectly well, or when exposed to residual humidity. That latter set of problems is particularly evident in mercury-free water clear poulyrethanes, such as the vanilla version of Innovative Polymers OC-7086 (TD 283-18 is much more forgiving).

To improve your odds when dealing with such tricky cases, it helps to have a pressure pot; the idea is to increase ambient pressure surrounding the mold to about 3-4 bar, thus crushing and dissolving back any existing bubbles, and discouraging the formation of new ones. Sure, it's a brute-force solution - but can you argue with its results?

Pressure casting equipment is more bulky, more expensive, and somewhat more dangerous than vacuum pumps (due to much higher pressure differentials) - and for most part, isn't necessary; get it only if you have plenty of room, and you are either forced to work with water clear resins that don't tolerate non-pressurized casting, or you are willing to spend at least $200 to improve your yields a tiny bit (say, from 85% to 97%).

[Binge]

See, I am quite afraid of using high pressure systems in my home.  I just don't have the security of having the right spot for something like that.  I will be able to use a vacuum system however

[Tarzan]

See, I am quite afraid of using high pressure systems in my home.  I just don't have the security of having the right spot for something like that.  I will be able to use a vacuum system however

Pressure systems do seem to be recommended for water-clear resins, to make sure any trapped air bubbles are microscopic.  I'm planning on tinting all my castings anyway, so my first setup will be vacuum.

Although I do have several pressure cookers and canning kettles in storage....  Hmmm.    

[domoaligato]

Domo.  I've been looking into vacuum systems to degas rubbers/plastics.  Have you found anything on allowing the plastics to cure in a mold under a vacuum?

yes and no.

you do not want to cure under a vacuum when the resin rises it will rise out of the mold.
when it falls you will have a huge mess to cleanup

[domoaligato]

ok so the results....

good and bad....

I will start with the bad.
1. shake the containers for part a and part b before you weight them. also stir them before you mix them to ensure that they are ready to go.

2. do not overdo the tint. I used just a little bit of purple on the end of a toothpick. too much....

This has resulted in a cast that is sticky and has not fully cured. I am not sure which one it is or a combination of both but my next attempt will be with only the clear resin and no tint to rule that out.

Good.
Pressure casting has ensured that I had 0 (zero) air bubbles in my cast. it is perfect except for the sticky/soft cast. I am going to let the first attempt sit for about 4-5 days as I have read that it may take eventually harden and to let it sit.

[domoaligato]

oh and I used 60 psi on the mold and 60 psi on the cast. this ensured that I have a mold with a nice smooth finish and less cloudyness on the cast do to the texture.

[Tarzan]

ok so the results....

good and bad....

I will start with the bad.
1. shake the containers for part a and part b before you weight them. also stir them before you mix them to ensure that they are ready to go.

2. do not overdo the tint. I used just a little bit of purple on the end of a toothpick. too much....

This has resulted in a cast that is sticky and has not fully cured. I am not sure which one it is or a combination of both but my next attempt will be with only the clear resin and no tint to rule that out.

Good.
Pressure casting has ensured that I had 0 (zero) air bubbles in my cast. it is perfect except for the sticky/soft cast. I am going to let the first attempt sit for about 4-5 days as I have read that it may take eventually harden and to let it sit.

Good to hear the pressure casting worked!  There's a nice air compressor for sale in my area on Craigslist, been eying it and wondering if I really need it.   

On the sticky casting, I hope it does cure in a few days.  I have one attempted mold in my garage that's still tacky, and it's been there since April.     No idea what I did wrong, I thought I had equal proportions of the part A and part B, but there you go.

[domoaligato]

did you make sure that your part a and part were shaken first?

also instead of dipping a toothpick and going straight to part b.... next time (not this next attempt) I will dip the toothpick and then wipe that on a piece of paper. then take a second toothpick and wipe it across the little line that I wrote with the first toothpick.

smooth-on named it strong tints correctly

[Tarzan]

did you make sure that your part a and part were shaken first?

also instead of dipping a toothpick and going straight to part b.... next time (not this next attempt) I will dip the toothpick and then wipe that on a piece of paper. then take a second toothpick and wipe it across the little line that I wrote with the first toothpick.

smooth-on named it strong tints correctly

I don't think I shook them at all, just some stirring.  Going to try making a different mold - platinum catalyzed latex (?) - then try the casting again.

[Binge]

ok so the results....

good and bad....

I will start with the bad.
1. shake the containers for part a and part b before you weight them. also stir them before you mix them to ensure that they are ready to go.

2. do not overdo the tint. I used just a little bit of purple on the end of a toothpick. too much....

This has resulted in a cast that is sticky and has not fully cured. I am not sure which one it is or a combination of both but my next attempt will be with only the clear resin and no tint to rule that out.

Good.
Pressure casting has ensured that I had 0 (zero) air bubbles in my cast. it is perfect except for the sticky/soft cast. I am going to let the first attempt sit for about 4-5 days as I have read that it may take eventually harden and to let it sit.

be careful with those sticky casts in gauging your results!  All of my sticky-casts have 0 bubbles   I'll take a picture when I get home... but they never harden.  They just stay mooshy.  If it is not hardening it means that it was not mixed correctly and/or there was too much moisture introduced into the casting.  This can come from the pigment and any moisture left in your silicon mold.

P.S. never cast urethane resins on a rainy/humid day.  wtf mate D: I am disliking this aspect of resins.

[Grim Fandango]

Awesome

[n0rvig]

Wow, I had no idea all this stuff existed. Neato. Looks awesome so far.

[domoaligato]

I am sure it is from the pigment. I will try again without the pigment tonight and try try again.

[domoaligato]

later I want to try something like this.

but I thought that starting with the pyro would spark more interest.

[SpAmRaY]

later I want to try something like this.

but I thought that starting with the pyro would spark more interest.

Show Image

^^ take my money!!!

[rurushu]

later I want to try something like this.

but I thought that starting with the pyro would spark more interest.

Show Image

when i first come across your thread, the first thing that comes into my mind is Domo-kun, and not Domoaligato's Domo, ^^'''
what would you like to do with Domo-kun? Raised on the caps? :D
cant wait to see your pyro's result!  :thumb:

[Batmann]

Although I do have several pressure cookers and canning kettles in storage....  Hmmm.   

Don't even think of it Greystoke, a pressure cooker won't support more than 15 psi.
If you try 60 psi it can simply blow your head, no joke (I've been there except that my head is still attached, luckily).
The safest/cheapest option is the harbour freight pressure pot.

[domoaligato]

Domo-kun in a style like boost's super hero's he doesn't make anymore.

[mkawa]

Although I do have several pressure cookers and canning kettles in storage....  Hmmm.   

Don't even think of it Greystoke, a pressure cooker won't support more than 15 psi.
If you try 60 psi it can simply blow your head, no joke (I've been there except that my head is still attached, luckily).
The safest/cheapest option is the harbour freight pressure pot.

i would not eff around with harbor freight for a pressure pot. get something high quality. your life is worth it.

[Tarzan]

Although I do have several pressure cookers and canning kettles in storage....  Hmmm.   

Don't even think of it Greystoke, a pressure cooker won't support more than 15 psi.
If you try 60 psi it can simply blow your head, no joke (I've been there except that my head is still attached, luckily).
The safest/cheapest option is the harbour freight pressure pot.

i would not eff around with harbor freight for a pressure pot. get something high quality. your life is worth it.

I hear you on the Harbor Freight quality - or lack thereof - just haven't found much else that looks like it's of decent quality and doesn't also cost $500.  Name brands like Binks, Devilbiss, or Graco all seem to be north of $800 new, and even beat-to-crap units on eBay still go for several hundred.  The HF unit is $99, which is hard to pass up. 

Still evaluating options, if anyone has recommendations I'm glad to hear them! 

[bueller]

Although I do have several pressure cookers and canning kettles in storage....  Hmmm.   

Don't even think of it Greystoke, a pressure cooker won't support more than 15 psi.
If you try 60 psi it can simply blow your head, no joke (I've been there except that my head is still attached, luckily).
The safest/cheapest option is the harbour freight pressure pot.

i would not eff around with harbor freight for a pressure pot. get something high quality. your life is worth it.

I hear you on the Harbor Freight quality - or lack thereof - just haven't found much else that looks like it's of decent quality and doesn't also cost $500.  Name brands like Binks, Devilbiss, or Graco all seem to be north of $800 new, and even beat-to-crap units on eBay still go for several hundred.  The HF unit is $99, which is hard to pass up. 

Still evaluating options, if anyone has recommendations I'm glad to hear them!

Shop around for a paint pot that's rated to 60psi, I know the ones sold locally in Australia will so that.

[Binge]

http://www.amazon.com/s/?ie=UTF8&keywords=pressure+paint+pot&tag=googhydr-20&index=aps&hvadid=22680825690&hvpos=1t1&hvexid=&hvnetw=g&hvrand=1737192564765464642&hvpone=&hvptwo=&hvqmt=e&hvdev=c&ref=pd_sl_5yi0ahzvyo_e

^ pressure paint pot 5x fast

[Binge]

I just got this response from a seller in regards to a vacuum chamber.

Hi: Sounds like a good project. I would say you need to degas the part while it is in the mould. The other issue is the pigment. What I have found is using to much will cause the Urethane to bubble. I believe it is the solvents in the pigment being effected by the curing heat but it may just be the pigment I use. The 3 Gallon is 9.75 inches inside but the pot does taper at the bottom about a 1/4 inch. Is this large enough to fit your mould? Phil

This pot costs $130-ish

[Tarzan]

http://www.amazon.com/s/?ie=UTF8&keywords=pressure+paint+pot&tag=googhydr-20&index=aps&hvadid=22680825690&hvpos=1t1&hvexid=&hvnetw=g&hvrand=1737192564765464642&hvpone=&hvptwo=&hvqmt=e&hvdev=c&ref=pd_sl_5yi0ahzvyo_e

^ pressure paint pot 5x fast

Thanks!  I hadn't actually thought to look at Amazon, even though I am a Prime subscriber...   

Most of the pressure pots listed, though, are only rated to 45 PSI, despite the notes from people pressurizing them above this level.  And I'll be honest, I've never heard of most of these brand names!  How about a good quality, made in America, over-built piece of industrial equipment?  Or do I have to pay $800 for that?   

[Binge]

http://www.amazon.com/California-Air-Tools-365-Pressure/dp/B008FQFW7W/ref=pd_sim_sbs_hi_8

rated to 80 PSI from a notable company in california

[domoaligato]

In my few days with the hb one.... the seal sucks ass and the safety valve kicks in randomly if you flow air in to fast.

I will be replacing the safety relief with a better one and applying silcone as a gasket instead of the rubber one it came with.

Spend the money tovget a better one.

[Tarzan]

In my few days with the hb one.... the seal sucks ass and the safety valve kicks in randomly if you flow air in to fast.

I will be replacing the safety relief with a better one and applying silcone as a gasket instead of the rubber one it came with.

Spend the money tovget a better one.

\

Thanks for taking one for the team, as it were, and testing out the HF unit!  Sorry to hear it's such a PITA, I'm definitely casting elsewhere for a pressure vessel.

[domoaligato]

Have you looked at resinaddict? They have reviews on most of the equipment.

[Tarzan]

My search for a pressure pot is over.  Saw a used unit on Craigslist yesterday, drove 100km after work to view it, and liked what I saw.



Meets all my criteria; made in US, high-pressure capable (110#), in reasonable condition, and large capacity.  Okay, I had no idea how large a five gallon paint pot was, it's freakishly huge, but I figure I can always fill it half full of sand or something to reduce the working capacity. 

Built in 1943 by the Pressed Steel Tank Company.  More pics once I get it cleaned up - also going to remove the paint stirring mechanism, replace the gasket and pressure valves, etc.  Yeah, I'll probably cost me a couple of hundred once it's done, but it was only $50 in current condition.

[domoaligato]

what I have seen a lot of people do is put a bunch of bricks in the bottom and put a circle cut piece of plywood on top.

sand may retain moisture and ruin your cast/mold. it may also blow up on your cast/mold when you fill the pot with air.

[Tarzan]

what I have seen a lot of people do is put a bunch of bricks in the bottom and put a circle cut piece of plywood on top.

sand may retain moisture and ruin your cast/mold. it may also blow up on your cast/mold when you fill the pot with air.

That's true, good points!  I also realized after I posted that sand is absolutely full of air pockets, so I'd be better off going with rocks or bricks, as you've suggested.

Got it the garage now, cleaning in progress...   

[domoaligato]

nice. I am interested in how the lid is designed on this model.

[domoaligato]

ok attempt #3 is crap. I am not sure if it is not hardening all the way because I am scraping the hardener from the hardener cup into the resin cup and not getting enough of the hardener out of the original cup.... or if it is humidity.

crystal clear 200 is a 100A:90B by weigh so I have been weighing 10 grams of part a and 9 grams of part b.
then dumping the part b into part a and scraping what is left from the cup as much as possible.
I think I am going to try to dump and scrape part a into part b instead to see if that helps.

I live in seattle and it is pretty warm atm. but at night it gets pretty cool. since the resin needs to be between 75-80 the whole time and I am doing this in my garage it is fine during the day but not acceptable at night. If this ends up being the issue then I am going to give up on crystal clear and go with onyx so I can sell some of these in black asap to recover my costs so my wife stops nagging me.

[Tarzan]

nice. I am interested in how the lid is designed on this model.

The shot below is before I started cleaning it, under a crust of dried paint spills I did discover a brass plate with Devilbiss and a model number, I'll have to look it up to see if I can find a list of specs.


Lid is held on by not four but six clamps, all in good condition, apart from the paint over everything.  Gauges and valves on the top are a real hodge-podge of stuff, I'm going to replace most of it with new stuff for peace of mind.

Boot is a size 10 1/2, for comparison...   

[domoaligato]

I like the 6 clamps instead of 4. nice find!