Sunday, March 27, 2016
Thursday, March 10, 2016
Under pressure, part 1
As was mentioned in my previous post, incorrectly labeled "What's new for March 2017" (whoops on the date), I am going to attempt to cast car parts via pressure casting. And as such, I will need both a vacuum chamber and a pressure pot.
There are a few options available for both vacuum chambers and pressure pots. Most of the vacuum chambers can be sourced via Ebay and consist of a stock pot, a large acrylic lid, fittings and a vacuum pump. The pressure pots fall into two varieties: pots designed especially for casting (expensive) and home brew paint pressure pots turned into casting chambers (cheaper but some hacking needed).
After quite a bit of research, I decided to attempt to kill two birds with one stone and make a combination vacuum / pressure pot. My one major consideration was that the pressure pot would be big enough to hold an O scale car side.
This requirement immediately ruled out the very popular Harbor Freight pressure pot conversion as the size isn't large enough. That left one option (without resorting to a professional model): the Grizzly Tools 20 Liter (5 gallon) Paint Pressure Pot. I was able to obtain this for the very reasonable price of $190.
As shown in the prior post:
One big advantage of the model (aside from its larger size), is the much more substantial clamping system that this pot has versus the Harbor Freight model. The pot has larger wing nuts that clamp down on metal protrusions from the pot, making a much more secure (and safer) hold on the lid.
One problem with this pot, however, is all the attachments that are installed on the lid, none of which I plan on using. All were easily stripped off with a wrench.
The now stripped top, after all attachments and fittings have been removed:
One large problem is the large hole now left in the center ... which of course is not threaded. The other holes are standard size and are threaded (1/4" and 1/2" in size).
After some internet research, it was shown that a 1" black pipe coupling with two caps and a liberal application of sealant filled the hole.
The view after the holes have been filled:
All but two of the holes have been plugged with caps. One hole holds a 60 psi safety / pressure release valve and the other holds the quick connect, a combination pressure / vacuum gauge and another 60 psi safety / pressure release valve (extra safety here!). I have a wall mounted regulator / moisture trap so that wasn't needed on the lid. Mounted on the inside of the lid is fitting that forces the air out at 90 degree angle. That way, when filling the pot, air won't blow directly on the molds splashing the resin.
Why the combination vacuum / pressure gauge? With the still in transit vacuum pump I ordered, I'll be able to use the pot as a vacuum chamber to degas my silicone rubber by connecting a hose to the quick disconnect fitting and then to the vacuum pump. Vacuum can be monitored on the gauge. I can then use the air compressor to fill the chamber with air to act as a pressure pot. Double duty!
Right now as I'm still waiting on the vacuum pump I am running a pressure test to see how long the pot will hold air. There are no obvious leaks, so that is good. I don't plan on pressurizing the pot over 50 psi, but started conservatively at 40 psi.
Once I get the vacuum gauge I will test the vacuum potential of the pot. But, I figure that if it can hold air, vacuum shouldn't be an issue.
Also mentioned in my prior post was that I couldn't locate the "in progress" photos of my news stand. Well, I found them so here they are:
I did make the roof removable for easy painting.
And as shown last post, now on the layout painted and with magazines for purchase:
There are a few options available for both vacuum chambers and pressure pots. Most of the vacuum chambers can be sourced via Ebay and consist of a stock pot, a large acrylic lid, fittings and a vacuum pump. The pressure pots fall into two varieties: pots designed especially for casting (expensive) and home brew paint pressure pots turned into casting chambers (cheaper but some hacking needed).
After quite a bit of research, I decided to attempt to kill two birds with one stone and make a combination vacuum / pressure pot. My one major consideration was that the pressure pot would be big enough to hold an O scale car side.
This requirement immediately ruled out the very popular Harbor Freight pressure pot conversion as the size isn't large enough. That left one option (without resorting to a professional model): the Grizzly Tools 20 Liter (5 gallon) Paint Pressure Pot. I was able to obtain this for the very reasonable price of $190.
As shown in the prior post:
One big advantage of the model (aside from its larger size), is the much more substantial clamping system that this pot has versus the Harbor Freight model. The pot has larger wing nuts that clamp down on metal protrusions from the pot, making a much more secure (and safer) hold on the lid.
One problem with this pot, however, is all the attachments that are installed on the lid, none of which I plan on using. All were easily stripped off with a wrench.
The now stripped top, after all attachments and fittings have been removed:
One large problem is the large hole now left in the center ... which of course is not threaded. The other holes are standard size and are threaded (1/4" and 1/2" in size).
After some internet research, it was shown that a 1" black pipe coupling with two caps and a liberal application of sealant filled the hole.
The view after the holes have been filled:
All but two of the holes have been plugged with caps. One hole holds a 60 psi safety / pressure release valve and the other holds the quick connect, a combination pressure / vacuum gauge and another 60 psi safety / pressure release valve (extra safety here!). I have a wall mounted regulator / moisture trap so that wasn't needed on the lid. Mounted on the inside of the lid is fitting that forces the air out at 90 degree angle. That way, when filling the pot, air won't blow directly on the molds splashing the resin.
Why the combination vacuum / pressure gauge? With the still in transit vacuum pump I ordered, I'll be able to use the pot as a vacuum chamber to degas my silicone rubber by connecting a hose to the quick disconnect fitting and then to the vacuum pump. Vacuum can be monitored on the gauge. I can then use the air compressor to fill the chamber with air to act as a pressure pot. Double duty!
Right now as I'm still waiting on the vacuum pump I am running a pressure test to see how long the pot will hold air. There are no obvious leaks, so that is good. I don't plan on pressurizing the pot over 50 psi, but started conservatively at 40 psi.
Once I get the vacuum gauge I will test the vacuum potential of the pot. But, I figure that if it can hold air, vacuum shouldn't be an issue.
Also mentioned in my prior post was that I couldn't locate the "in progress" photos of my news stand. Well, I found them so here they are:
I did make the roof removable for easy painting.
And as shown last post, now on the layout painted and with magazines for purchase:
Friday, March 4, 2016
What's new for March 2017
Just some updates on some outstanding projects that I've been working on ...
I've starting painting my three CSL cars, using all Tru-Color paints:
The colors used were (all Tru-Color paints):
All the attachments for painting have been removed from the lid. I just need to plug some holes and add my valves and gauges.
Most folks use the 2 1/2 gallon Harbor Freight pressure pot, but this one is larger (approx. 14" wide by 12" deep, necessary to fit an O scale car side) and is much more sturdy in construction. The wing nuts for securing the lid are much more substantial than the Harbor Freight model.
I've also started working on a small brick store front that will go next to my Southport station house.
This was another quick "scrap box" build made of of parts that I had laying around in various scrap boxes. The front of the building is N Scale Architect brick sheeting while the sides and back are JTT Scenery brick sheets. I still need to add stone lintels and other embellishments and clean up some of the mortar, But I did it this way (painting and mortaring before adding stone lintels) as it is much easier to paint. The store front (the white portion) was made separate from the brick and is a press fit. Much easier to paint separately.
I've also finally attached the trucks to my other Q-Car 4000 series Plushie:
Next up is sending the car to the paint shop.
And finally, some random photos from the layout:
And as always, thanks for visiting!
I've starting painting my three CSL cars, using all Tru-Color paints:
 |
| First is the cream |
 |
| Then red underneath the windows |
 |
| Red for the letterboards |
 |
| Brown for the doors |
- Passenger Car Interior Cream
- Caboose Red
- Sante Fe Brown
- Pullman Green (for underbody and trucks in bottom photo)
I still need to find an appropriate dark grey for the roof, paint the window sashes and do final touch-ups. But progress has been made!
I've also finally added ground cover to the Sheridan curve along with some background trees:
I still need to "tidy" things up, but a little ground cover is better than bare plywood.
I've also added a magazine stand next to my Southport station house. This was a quick build that was made out of pieces from the scrap box. I can't seem to locate the "in progress" photos so the "semi-finished" photos will do. I've added 50 or so O scale magazines for sale. I just need to add some newspapers now:
I may add some additional magazine racks and some other details. But for now, there is a pretty good selection of periodicals for my O scale citizens.
I've also finally added ground cover to the Sheridan curve along with some background trees:
I still need to "tidy" things up, but a little ground cover is better than bare plywood.
I've also added a magazine stand next to my Southport station house. This was a quick build that was made out of pieces from the scrap box. I can't seem to locate the "in progress" photos so the "semi-finished" photos will do. I've added 50 or so O scale magazines for sale. I just need to add some newspapers now:
I may add some additional magazine racks and some other details. But for now, there is a pretty good selection of periodicals for my O scale citizens.
I've also begun collecting the necessary equipment for pressure casting. Previously. my mold making and casting was done without vacuuming either the silicon or pressurizing the castings. In order to make better castings of cars, I recently acquired a pressurized paint pot:
I will use this for both vacuuming silicone (vacuum pump has been ordered, just not yet received) and for pressure casting. While used for painting, the pot can be easily adapted to pressure casting.
All the attachments for painting have been removed from the lid. I just need to plug some holes and add my valves and gauges.
Most folks use the 2 1/2 gallon Harbor Freight pressure pot, but this one is larger (approx. 14" wide by 12" deep, necessary to fit an O scale car side) and is much more sturdy in construction. The wing nuts for securing the lid are much more substantial than the Harbor Freight model.
I've also started working on a small brick store front that will go next to my Southport station house.
This was another quick "scrap box" build made of of parts that I had laying around in various scrap boxes. The front of the building is N Scale Architect brick sheeting while the sides and back are JTT Scenery brick sheets. I still need to add stone lintels and other embellishments and clean up some of the mortar, But I did it this way (painting and mortaring before adding stone lintels) as it is much easier to paint. The store front (the white portion) was made separate from the brick and is a press fit. Much easier to paint separately.
I've also finally attached the trucks to my other Q-Car 4000 series Plushie:
Next up is sending the car to the paint shop.
And finally, some random photos from the layout:
And as always, thanks for visiting!
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