Hmmm, it's got me wondering if maybe you could McGyver something up with an old pressure cooker and a vacuum cleaner?

I dunno, just thinking out loud...

Dodgy

 

 

CapnMac82

 

 

Dodgy

So the US has oxygen thieves too.

 

 

Normally, we put them in elected political office, but their spawn & illk run about loose, too.

Curse of having 350 million population.

And crammed into a space not that much larger than Oz.

 

 

 

 

Hey CapnMac, I feel for you folks, but even though we have a much smaller population, the oxygen thieves seem to be taking over this country.

 

Going to the doctor last week and come across a series of about a dozen road signs saying:

"RIGHT LANE ENDS- MERGE LEFT"

And there were about a half-dozen guys in the right lane just driving happy along, not trying to get over into the middle lane at all.

About three miles / five kilos of signs and then the right lane is blocked. So we have all six or so drivers trying to force their way over into the middle lane. Had to hit the brakes to keep from running into a Kia.

I MEAN A DOZEN FRIGGIN' SIGNS OVER THREE MILES/FIVE KILOS AND YOU COULDN'T FRIGGIN' READ THEM!?!?!

Gamera

Hmmm, it's got me wondering if maybe you could McGyver something up with an old pressure cooker and a vacuum cleaner?

I dunno, just thinking out loud...

 

Nice thought Gam, but it is opposite of what I need. What you are describing is a vacuum chamber. What I really need is pressure going into the pot and that forces the air bubbles to collapse or compress into tiny mostly unseen particles. But some people make pressure pots from pressure cookers. So you are not all that off with it.

Ahhhhhhhh, okay. I was thinking you wanted to lower the pressure to get the bubbles to come out of solution. My mistake!

Gamera

Hmmm, it's got me wondering if maybe you could McGyver something up with an old pressure cooker and a vacuum cleaner?

I dunno, just thinking out loud...

 

Nice thought Gam, but it is opposite of what I need. What you are describing is a vacuum chamber. What I really need is pressure going into the pot and that forces the air bubbles to collapse or compress into tiny mostly unseen particles. But some people make pressure pots from pressure cookers. So you are not all that off with it.

Sorry, duplicate post 

Gamera

Ahhhhhhhh, okay. I was thinking you wanted to lower the pressure to get the bubbles to come out of solution. My mistake!

 

Its kind of an odd thing. Depending on the type of resin, some people will degass resin that way, as you are thinking but, it will only reduce the bubbles. A pressure pot is the best way to insure a bubble free cast. 

A vacuum chamber is most often used to degass silicone. This is where a vacuum chamber shines. The silicone is put into the vaccum chamber and air bubbles are pulled out. Then the silicone is poured for the mold. I didn't need to do this to make my mold because the silicone did a good job keeping bubbles from the surface layer. Here is the thing though. If I put my mold in a pressure pot to cast my resin, the pressure may force trapped air in the mold to the surface. This then would cause more imperfections in the cast!. I am hoping that I wont have that issue at the lower tank pressure of around 20 lbs. Most people use tank preasures in the 60 to 70 pounds range when working with resin. The jury is out. I will soon find out if the lower pressure will work. Like I said in another post, there are people out there that have tried it at 20 lbs or less and claim the lower pressure works.

So basically Gam, serious casters will degass silicone via a vacuum chamber, make the mold, when the silicone mold is cured, then pour resin into the mold, then place the mold into a pressure pot until the resin cures. This ensures a bubble free cast. The caveat is that the mold has to be  designed correctly. A bad mold design will cause airpockets that no pressure pot can overcome. And that might be how I end up with mine. We shall see.

Gamera

Going to the doctor last week and come across a series of about a dozen road signs saying: "RIGHT LANE ENDS- MERGE LEFT" And there were about a half-dozen guys in the right lane just driving happy along, not trying to get over into the middle lane at all. About three miles / five kilos of signs and then the right lane is blocked. So we have all six or so drivers trying to force their way over into the middle lane. Had to hit the brakes to keep from running into a Kia. I MEAN A DOZEN FRIGGIN' SIGNS OVER THREE MILES/FIVE KILOS AND YOU COULDN'T FRIGGIN' READ THEM!?!?!

Yes Cliff, they read them. They know exactly what they are doing.

About like the  idiots coming on a three lane freeway, jumping to the left lane, only to jump back to the right lane to take the next exit a half mile from where they got on.  Just to get there two cars ahead......,.

goldhammer88

About like the  idiots coming on a three lane freeway, jumping to the left lane, only to jump back to the right lane to take the next exit a half mile from where they got on.  Just to get there two cars ahead......,.

 

Yeah, you and Greg are right, I just needed to vent...

Bakster

 

 

Gamera

Ahhhhhhhh, okay. I was thinking you wanted to lower the pressure to get the bubbles to come out of solution. My mistake!

 

 

 

 

Its kind of an odd thing. Depending on the type of resin, some people will degass resin that way, as you are thinking but, it will only reduce the bubbles. A pressure pot is the best way to insure a bubble free cast. 

A vacuum chamber is most often used to degass silicone. This is where a vacuum chamber shines. The silicone is put into the vaccum chamber and air bubbles are pulled out. Then the silicone is poured for the mold. I didn't need to do this to make my mold because the silicone did a good job keeping bubbles from the surface layer. Here is the thing though. If I put my mold in a pressure pot to cast my resin, the pressure may force trapped air in the mold to the surface. This then would cause more imperfections in the cast!. I am hoping that I wont have that issue at the lower tank pressure of around 20 lbs. Most people use tank preasures in the 60 to 70 pounds range when working with resin. The jury is out. I will soon find out if the lower pressure will work. Like I said in another post, there are people out there that have tried it at 20 lbs or less and claim the lower pressure works.

So basically Gam, serious casters will degass silicone via a vacuum chamber, make the mold, when the silicone mold is cured, then pour resin into the mold, then place the mold into a pressure pot until the resin cures. This ensures a bubble free cast. The caveat is that the mold has to be  designed correctly. A bad mold design will cause airpockets that no pressure pot can overcome. And that might be how I end up with mine. We shall see.

 

 

Thanks for explaining that. I understand a lot better now where you're coming from.

Gamera

I just needed to vent...

I know. I vent all the time when I'm driving. Most of the time my wife quietly tries to ignore me. One of these days, i think she might whack me up the side of the head with something, though.

Just so you know, these merge-morons are one of my favorite 'venting' subjects.

Greg

Yes Cliff, they read them. They know exactly what they are doing.

I'm not convinced of that.  That would require that they pay attention any further than the sellphone they have pinned to the 12 o'clock position of their steering wheel.

And, @Gamera, it's funny, my PCP MD office is at the end of a Right Lane Must Exit, which is fine if I'm exiting there.  When I need go further than the doc's office is where I see commercial drivers not bothering to pay atention to he signs, and only lane changing at the last second.

So, traffic right there slows to a crawl at virtually ever hour of he day.  Which is why I'm often willing to spend $5-6 to take the toll expressway to go around that traffic embolism.  (I once paid near $30 in tolls on that road to get the 20 miles to Fort Worth in only 45 minutes rather than the 2 hours the "freeway" would have required.)

Now, back to Baxter's build.

Actually, a vaccuum pot can help with casting resin, since the reduced pressure will "draw" the bubbles to the surface.  This even works with many molten metals, too.  The bowl turning guys I know swear by vaccuum pots for their resin casting, and resin blanks on a lathe really, really, do not "like" bubbles or similar voids in them.

Now, at a c-note per bowl, cobbling up a vaccuum pot for resin blanks is not a big deal, Bakster's Basement, however, may not have that level of cost or time expenditure available.

Life is complicated that way.  Whether we'd prefer it to be so or not.

CapnMac82

 

 

Greg

Yes Cliff, they read them. They know exactly what they are doing.

 

 

I'm not convinced of that.  That would require that they pay attention any further than the sellphone they have pinned to the 12 o'clock position of their steering wheel.

And, @Gamera, it's funny, my PCP MD office is at the end of a Right Lane Must Exit, which is fine if I'm exiting there.  When I need go further than the doc's office is where I see commercial drivers not bothering to pay atention to he signs, and only lane changing at the last second.

So, traffic right there slows to a crawl at virtually ever hour of he day.  Which is why I'm often willing to spend $5-6 to take the toll expressway to go around that traffic embolism.  (I once paid near $30 in tolls on that road to get the 20 miles to Fort Worth in only 45 minutes rather than the 2 hours the "freeway" would have required.)

Now, back to Baxter's build.

Actually, a vaccuum pot can help with casting resin, since the reduced pressure will "draw" the bubbles to the surface.  This even works with many molten metals, too.  The bowl turning guys I know swear by vaccuum pots for their resin casting, and resin blanks on a lathe really, really, do not "like" bubbles or similar voids in them.

Now, at a c-note per bowl, cobbling up a vaccuum pot for resin blanks is not a big deal, Bakster's Basement, however, may not have that level of cost or time expenditure available.

Life is complicated that way.  Whether we'd prefer it to be so or not.

 

Yeah it depends on what the end goal is it seems, how you are using it. Turning it on a lathe takes it into different realm. And then the type of resin has to be considered because vacuum pots take time to degass the material, and fast acting resin like I am using doesn't offer the luxury of time. It would cure before you'd get it out of the pot. I have watched many videos on mold making/resin casting, and processes seem to take on an artform. There are many things to consider. Hence, why I didn't want to dabble with casting on this project because it's a time suck, and it surely ended up being that. But the wheel gremlin had different ideas for me and I have no choice but to punch it square in the face. For my purposes, I think a pressure pot is the best option.

I agree with your Captain on paying the toll to escape the extra stress and aggrevation. As I get older I'd rather just get where I'm going even if it costs more. 

Bakster best o' luck and please keep on keeping on keeping us informed. This is all new to me and I'm learning with each post. 

Gamera

Bakster best o' luck and please keep on keeping on keeping us informed. This is all new to me and I'm learning with each post.  Add

Thanks Gam. New to me too but I am learning. Barring any drama this weekend, I will begin getting material for the pressure pot. I am really dreading all this, I just want to build a model. Dang it. Lol.  

Where do you go if it dosn't work Bako? A search for different wheels?

Bakster

 

 

Gamera

Bakster best o' luck and please keep on keeping on keeping us informed. This is all new to me and I'm learning with each post.  Add

 

 

Thanks Gam. New to me too but I am learning. Barring any drama this weekend, I will begin getting material for the pressure pot. I am really dreading all this, I just want to build a model. Dang it. Lol.  

 

 

Well Bakster you have finally and convincingly confirmed what we have all surmised for many years. Scale modeling really is a pressure cooker of a hobby!

Hang in there, even though it's incredibly frustrating you certainly are learning a lot of new skills in a wide variety of areas. What's that old saying? That which does not kill us...

Dodgy

Where do you go if it dosn't work Bako? A search for different wheels?

 

THAT-- is a good question. I have already done an exhaustive search but sometimes, when you least expect it, a situation presents itself. Long story short-- yeah-- that would probably be the plan and taking it back to square one. 

I am holding hope I will get through this with the PP. 

Back to the bench

Well Bakster you have finally and convincingly confirmed what we have all surmised for many years. Scale modeling really is a pressure cooker of a hobby!

Laughing! SO TRUE! And I am the poster child for it. You could put my face on a milk carton. 

Back to the bench

Hang in there,

Thanks for the support!

Back to the bench

though it's incredibly frustrating you certainly are learning a lot of new skills in a wide variety of areas.

That is also, SO TRUE. Casting is something I have wanted to learn and yes, I have already learned a bunch. The problem is, I am like a mule. I dig my feet in while the good Lord is pulling my bridle, "Come on you stubborn donkey! I am trying to give you what you want! Move them feet!"

Lol. And the solution may be just feet ahead, a solution of many new doors to walk through.

Back to the bench

What's that old saying? That which does not kill us...

True! Killed by an exploding pressure pot! LOL

Speaking of a PP.  In donkey fashion, kicking and screaming, I am relenting. I decided that I will order a PP verses a DIY. Why? Because for a little over $100 I can repurpose one for casting. It will be safer than a PVC DIY that I was going to do, and really, the cost variance is not that much. In the end I should have a decent setup for future projects. No, it's not a really well built pot like what I was looking at early on, but this is $300 cheaper, and it will do the job. Many resin casters use this pot.

So that is the latest from Bakoland.

Hee Haw!

Gil: Yeah pressure cooker is an apt term!

Bakster: Crossing my fingers the pressure pot works out!

Gamera

Gil: Yeah pressure cooker is an apt term!

Bakster: Crossing my fingers the pressure pot works out!

 

Thanks Gam!

Good luck mate. I'll be waiting to hear the results and I doubt very much that your investment will be wasted.

Bakster

So that is the latest from Bakoland.

Hmm, read that and had to immediately wonder if that ought scan as "bah KO lahnd" or as "BAKE" oh land" 

Particularly after discussions of pressure cookers.

Or becasue of the saurkraut I have simmering . . .

CapnMac82

Or becasue of the saurkraut I have simmering . . .

Lol. My Polish parents would be proud of you. A favorite of theirs.

I was going with BAA-KOO since it sounds like Baka which is Japanese for silly or foolish person! 

Not that I'd consider you silly or foolish! 

BTW: Could maybe these be of some use to you?

https://www.greenstuffworld.com/en/172-cogs-and-gears

Also, calling me Cliff is fine. I call you Bakster instead of Steve since I know about five Steves around here and Bakster is just less confusing! 

Gamera

BTW: Could maybe these be of some use to you?

Thanks, but no, I already researched those.

The good news is that the pressure pot promises the path thru. I had good test fires, and I should be doing a big update in the coming days. 

Sorry, got their email the other day and was looking though their website. Figured you'd already seen it but thought it was worth a shot. Hope the pressure pot works out. 

YOU GET WHAT YOU PAY FOR

I followed this fellers instructions to convert a Harbor Freight Paint Tank:

https://www.youtube.com/watch?v=5jOttgLQvpA

I found several videos that explain how to covert this tank and by far this is the best. The man tells you everything that you need to know and it made the process easy.

Below: My rig

So, I make the changes and begin filling the pot with air.  At around 30 lbs, hisssssssssssssss. The tank leaked air like a sieve. I localized the leak to the cover and it was leaking air past the gasket. I crank the bolts down and still, no improvements. I remove the lid and try repositioning it, still no improvement. Eventually, I search the internet, low and behold, this is a common problem with this tank. Some say to crank the bolts more, some say to apply silicone grease to the gasket, some say to make a new one out of silicone rubber. I inspect the gasket and what a piece of (beep). "You get what you pay for..."

Well, since I happen to have silicone rubber compound, I set out to make a new gasket. I pull the shoddy gasket, mix silicone, and make the pour.

Below: The gasket that came with is white, what I poured is blue.

Once cured I tried it again. After hand tightening, I gave the bolts an additional twist using channellock pliers. I attached the air hose and what do you know, I was able to load 50lbs. The tank is rated for 60 so I stayed below that. 

Time to pot a cast. I started with using Puduo. I did the PBJ method of loading resin on both pieces, poked at areas that trap bubbles, slap the halves together, band the mold, and into the pot it went. This resin is slow curing, so I left the mold under pressure for  a good 24 hours. 

Here is the difference. The left cast under pressure, the right with no pressure. The difference is "clear." Many of the bubbles in the unpressurized piece reached the surface of the piece causing divots. It would have been a lot of work to fix. The pressurized piece came out absolutely perfect. I had flash to clean, but that is true with either.

So, I tried the Smooth On resin and it came out perfect. And with both resins the pressure moved material into all the areas I had problems with. Every gear nub came out perfect, as well as the rivets. 

Below: Before clean up.

After clean up

Whats the moral of the story? Sometimes you just need the right tools. I don't think I would have ever reached the goal without a PP. There is a lot more I could note but it is too much work. If anyone has questions, let me know.  I will note this though:

1. I will use the Smooth On resin for the final pieces. It is stronger, lighter, and easier to sand than the Puduo. I think the Puduo resin I have is going bad because it remains somewhat pliable. It takes a few weeks to firm up and even then, body heat of handling causes it to become a little pliable. The stuff is over 3 years old now so ... probably bad.

2. I cast the above pieces using my second mold, not the third one that I made. Either would work but the third one is more difficult to demold with the added vents. 

So, that is that. I have another cast in the pot. Moving forward I need to make a master for the other side of the vehicle. Then make another mold and cast. 

Hopefully, soon, I can get back to assembling the model. I almost forgot what I am doing here, building a model or casting?

Anyhow, I am glad for all this. I learned a new skill and I am already scheming some casting ideas. 

Very nicely done.  Way to go, you little problem solver, you.