Rudy Kouhoupt's Open Column Steam Engine - Cast & Double Size

[vederstein]

... I've picked up some quite dense insulation foam from the local hardware store and I expect it to work better than normal Styrofoam...

Prior to purchasing the flower arrangement foam, the wife and I did stop at Home Depot for insulation foam. We took her car. the pink foam boards were 4x8 ft sheets (1.2 x 2.4 m). Far too big to fit in the car. Also far too much for this project.

So that's when we drove to a hobby store and purchased the flower foam.

Live and learn....

I'm thinking of liberating some packing foam from the trash at work. Does anyone have any experience with that material?

...Ved.

 

[vederstein]

I went to Home Depot to pick up some 5 gallon contractor buckets and this time they had 2 ft x 2 ft sheets of pink insulation foam. So I purchased a sheet and made a mold from that material.

Then I embedded the two molds into sand and performed the pour. I thought I could control the pour better, but I melted the bucket. As a side note, I guess there's a yin and yang performing an aluminum pour in 15 deg F (-9 deg C) weather with snow on the ground.

Yin: It's damned cold outside.
Yang: I can use the snow on the ground to cool the parts.
​

After pulling the castings, I was a bit astonished how good they came out considering how inexperienced I am. There were no voids due to bad mold positioning. The first part, made from polystyrene was the worse of the two and I decided not to mess with that one anymore. The laminated construction of the mold was clearly visible and my cutout looked bad. Also the coarseness of the polystyrene gave a bad surface finish.

The other part, made from the pink foam matched the mold. As Cogsy said, the finish matched the finish of the foam. It was a bit coarse for my liking, yet not near as rough as the polystyrene. I continued to machine one part to see...

 

[vederstein]

As I machined one of the bearing blocks, again I was a bit astonished how acceptable the casting quality actually was. There was no porosity!

The casting, like all castings, have a hard crust that my carbide tooling made quick work of. As I was removing the crust I found that a bit of grinding would smooth out the roughness of the finish and make it look more like a sand cast part.

My biggest disappointment was that the part wasn't symmetrical. It's functional, but that flaw may be too much for me to accept. I blame the fault on my unsteady hand when creating the mold.

I plan on creating the part a third time using the lost wax (or PLA) method when I figure out how to use the 3D printer.

Overall I'm pleased with today's outcome. It's certainly not perfect, but better than I expected for a first ever lost foam pour of molten aluminum.

As a side note, does anyone remember how to put photos within the text instead of always at the end of the text block?

...Ved.

 

[Cogsy]

Before I get to the picture placement, I have a potential tip for the foam finish. I have made some molds from the insulation foam (it was yellow, not pink and the 'flat' surface as purchased is perfectly smooth) and spent a bit of time sanding them, as well as also filling any imperfection/joins with a foam dust and PVA glue mixture. I also ran a thin coat over all the cut edges. The molds are now quite smooth and I'm hoping for some good surface finishes from them. Now I just need some finer sand than I have in stock, and some time combined with nice weather to test it out.

For the pictures, upload them through the 'manage attachments' button as usual. As you get to a point in your post where you want a picture, click on the paperclip icon on the top of the post box and a dropdown will show with the names of your uploaded pics. Click on the one you want to add and it will insert. It's best to leave a blank line before and after each pic and pay attention to the names of your pictures - it's possible to add the same one multiple times in the same post.

 

[vederstein]

I've had the 3D printer up and running for a couple days now after receiving the new electronics. Now that I have the catastrophic issues taken care of, it's just normal 3D printing issues.

I'm having raft curling issues which eventually blow up the prints.. The printer does not have a heated bed yet. I have the actual heated bed, but it requires a separate, external power supply. That's something I'm working on and should have resolved in about one week. Therefore I'm making some design changes to split some of the taller components into smaller pieces that I'll glue together prior to casting.

 

[vederstein]

...I've got a cold drafty old house that was built in 1890 and my printer is sitting in the corner next to 2 outside walls....

My house is a split level built in 1974. Not as old as yours, but approaching 50. With the frigid weather lately, I'm probably in the same boat as you.

...Ved.

 

[Cogsy]

My house is a split level built in 1974. Not as old as yours, but approaching 50..

This line gave me shivers - I was born in 1974 . I don't feel like I'm approaching 50 yet

 

[vederstein]

The print of the half posts was successful. I glued them together trying both hot melt glue and white school glue.

Either way I have some crevices in the juncture. This will be a lost PLA pour. Therefore I need to encapsulate the posts in investment (a 1:1 mixture of plaster of paris & sand) and every little crevice will be filled. Therefore I'll run a bead of hot melt in the crevice and machine the excess material on the lathe after the aluminum pour.

 

[vederstein]

...Now I just need some finer sand than I have in stock...

I've read that aquarium sand is very fine in texture.

...Ved.

 

[vederstein]

Investment Pour:

I took some cardboard packaging and taped up a cylinder. You will notice that I pushed through some nails to keep the mold in place so I didn't float to the top.



Then I mixed in about 1-1/2 to 1 ratio of plaster of paris and sand in a freezer storage bag. I thought I was being clean, but more on that after the photo.



After adding water and kneading the investment. I poured the investment into the mold. Everything went wrong. I didn't mix the material enough so it was globby. The bottom of the cylinder, which was made of duct tape began to leak. Then investment broke through the side of the cylinder and plaster got everywhere. I don't have a picture of the mess because I was too busy cleaning it up.



So what does one do? Examine the failure and try again!!! I remade the cardboard cylinder re-enforcing it where it broke out. I mixed the investment in a bucket and large spoon.

After the much more successful investment pour, I used an oscillating tool to vibrate the cardboard cylinder to try to eliminate bubbles.



Coming next: Burnout.

...Ved.

 

[vederstein]

Today I did the burnout and aluminum pour of the posts.

The burnout went fairly well. I placed the cured investment in the furnace upside down. The burn started at a low fire for 30 minutes then I jacked it up to a roaring burn for about an hour.





I noticed that the investment didn't fully fill the below the mold, but I forged ahead anyway embedding the investment into sand after blowing it out with compressed air. (The black bars are from the pieces of steel roundstock I had under the investment to let the heat in.)



Here's a video of the pour and breakdown.

[ame]http://www.youtube.com/watch?v=oRYpEzD8nVY[/ame]

As you can see, I had not a useable part out of the four posts. :wall: I guess I should pour one at a time. Perhaps a taller sprue? Perhaps a mold that fills from the bottom with an air vent to the top? I welcome comments and insight.

On the plus side, where the casting did come out well, it was so well defined I could see the layers from the 3D print.




On the other hand, perhaps I should start modelling ruins from the Classical Age (ancient Greece & Rome). ;D

...Ved.

 

[WSMkid]

Today I did the burnout and aluminum pour of the posts.

The burnout went fairly well. I placed the cured investment in the furnace upside down. The burn started at a low fire for 30 minutes then I jacked it up to a roaring burn for about an hour.

View attachment 92985
View attachment 92986
View attachment 92991

I noticed that the investment didn't fully fill the below the mold, but I forged ahead anyway embedding the investment into sand after blowing it out with compressed air. (The black bars are from the pieces of steel roundstock I had under the investment to let the heat in.)

View attachment 92988

Here's a video of the pour and breakdown.

http://www.youtube.com/watch?v=oRYpEzD8nVY

As you can see, I had not a useable part out of the four posts. :wall: I guess I should pour one at a time. Perhaps a taller sprue? Perhaps a mold that fills from the bottom with an air vent to the top? I welcome comments and insight.

On the plus side, where the casting did come out well, it was so well defined I could see the layers from the 3D print.

View attachment 92989
View attachment 92990

On the other hand, perhaps I should start modelling ruins from the Classical Age (ancient Greece & Rome). ;D

...Ved.

Was your investment pre heated at the time of pour?

No personal experience but that seems to be a must to help prevent flashing.

Thank you for sharing.
Always following,

GJ

 

[vederstein]

Was your investment pre heated at the time of pour?
GJ

It was about 15-25 minutes between pulling out the glowing hot investment from the furnace to the pour. I embedded the investment in the sand while the furnace was melting the aluminum. Being that the investment is a good heat insulator, Just prior to the pour, I looked inside the investment, the glow was just about extinguished. Therefore I'm quite sure it was hot during the actual pour.

How hot? No idea. Perhaps I should bring back home my infrared thermometer from that I keep at work.

I guess another option is that I can make a second burner so I can perform the burnout and the melt at the same time. Opinions?

As for other items on this project, I received the power supply for the 3D printer's heated bed and will be installing it in a day or two. Also I managed to print a single entire post. This is my next post mold. Info to follow...



My wife said the part looks like a toilet paper roll holder. I can't say she's really wrong on that account.

...Ved.

 

[WSMkid]

Ved,
Glowing investment, to me, would be hot enough at a guess. I want to say the guy in the YouTube vids I've watched was keeping them in his kiln at 900(or was it 1800) degF until seconds before the pore. I'm not sure if this is the proper way or not but he had spectacular results.

After looking more at your last pour it does look like freezing. Keep in mind I had a three hour lecture/lab on casting freshman year (about 4 years ago now) so I'm for sure not an expert, just sharing thoughts.

I was thinking a paint roller holder spindle but I can see the toilet paper holder.

Keep us posted!

GJ

 

[vederstein]

Ved,
... looking more at your last pour it does look like freezing. ...

Freezing is a term I'm unfamiliar with. (Remember I'm a complete newbie at this.) Can you please elaborate?

Thanks,

Ved.

 

[charlesfitton]

On the other hand, perhaps I should start modelling ruins from the Classical Age (ancient Greece & Rome). ;D

...Ved.[/QUOTE]

Yep - sell them online to the wargamer/fantasy gaming crowd...

 

[WSMkid]

In my terms its when the metal solidifies in a mold as its being poured leaving voids and such.
There may be a better/real term for this, if there is someone please correct me.
I'm delighted to hear that burning out your models worked so well just using your furnace (in terms of cleaning everything out).

GJ

 

[bouch]

Today I did the burnout and aluminum pour of the posts.

As you can see, I had not a useable part out of the four posts. :wall: I guess I should pour one at a time. Perhaps a taller sprue? Perhaps a mold that fills from the bottom with an air vent to the top? I welcome comments and insight.

On the plus side, where the casting did come out well, it was so well defined I could see the layers from the 3D print.

...Ved.

I'm no expert, but it seems like none of the columns had the lower part of the mold filled. That suggests to me trapped air which prevented the metal from filling the mold.

I think you're going down the right path thinking about adding air vents. Seems like you could either add vents from the bottom to the top of the sand or your idea of a central "shaft" to fill the columns from the bottom and then the air vents at the top.

You would know your mold is filled when metal comes out of the air vents.

 

[vederstein]

... I think you're going down the right path thinking about adding air vents...

I talked to a co-worker that has some limited casting experience from college. (which is strange because he's an electrical engineer). He said to fill from the top with a bottom vent.

That will be my next pour.

 

[vederstein]

I got the heated bed installed and took a big leap. I printed off the cylinder head and steam valve. This was the first truly large part I printed. It's a little over 3-3/4" diameter.



The orientation on the bed certainly was risky with all the support material and not very material efficient. But I wanted the text on the cylinder head not marred by support material and I have these round bosses that I want concentric so I can chuck on to them when the parts get machined.





I'm quickly getting to to point where I need to pour a lot of investment and start melting down my Corvair engine.

...Ved.