Jumbo Coin Casting/Soule Steam Festival/Ursutz Burner/Bound Sand Molds

Here is a photo from the same guy that Jammer posted above, with a reference.

I think the guy said he was a retired watchmaker, and all of his engines ran like Swiss watches too.

 

Impressive.

 

Here is an example of a resin-bound sand mold.
The molds are made in a snap-flask (just wood screwed together; one day I will add hinges).
Once the mold has set, the flask is removed, and the two mold halves are glued together with furnace cement.

I have had the furnace cement break on one mold while I was pouring it, so I started adding some weight on top of the mold when I pour it.

The benefits of using bound sand are that the accuracy of the parts is greatly improved.
For larger parts, bound sand is not really necessary, but for small steam engine parts, the bound sand really helps keep things accurate, and reduces machining time considerably.
Bound sand molds (in my opinion) are the next best thing to the lost wax method, and much simpler than the lost wax process.

You can also carve runners, gates and sprue holes into the hardened sand with a rotary wood rasp mounted in a drill or tool and die grinder, but I generally just form the basin, runners and gates into the mold.

In the photos below, I made two molds, and cemented them together, so that I could pour two cylinders at the same time (I only had one pattern).

Others have pointed out that the riser on top of the molds is probably not necessary, and I tend to agree. I use wood strips as dams on top the mold to catch the aluminum that comes up out of the vent holes.
The highest points of the mold generally have to be vented with bound sand, since the sand does not breath well, and will trap large air bubbles without vents.

I tried using Adolf's inserts to keep things aligned, and that did not work, so I have gotten away from using those. I think now I just stick a 1/4" steel rod through the mold in a couple of places for alignment (if I remember correctly).

 

Here is a link to a flywheel I cast.
This was a quickie effort that I did not expect to work, and so I did not spend any time using any risers, and had a little shrinkage in the rim.
I think the part is usable, but as a "proof-of-concept" test, it turned out far better than I ever expected.

http://forums.thehomefoundry.org/index.php?threads/cretors-jumbo-flywheel-cretors-popcorn-engine.48/


And some steam engine cylinder molds (the ones in the photo above):
http://forums.thehomefoundry.org/index.php?threads/casting-multiple-parts-from-a-single-pattern.121/

 

And here is the base that goes with the cylinders above:

1st Attempt:
I had absolutely no clue as to what I was doing here. Very coarse core sand. Way too much sodium silicate. Petrobond mold that failed and ruined the piece. Pattern made of balsa wood (LOL). Tiny gates, no runners. Overheated melt.
This is one of my very early casting attempts. More of a "how not to cast" lesson.

This was poured upright.

 

Second attempt on the base:

Melt was too cold, causing a partial mold fill (is that called a "cold shut"? I forget the correct term.)
Core was petrobond this time. I still was clueless at this point.

This one was also poured upright.

 

Third Base Attempt:

Poured way too hot this time. The heat caused the metal to erode the sand badly, producing a terrible finish.

Also poured upright.

Got a complete mold fill, but otherwise still not usable in my opinion.

 

Forth Base Attempt:

At this point, people like HT1 were pointing out good gate/runner/riser books (thanks much for that), and I changed to an inverted mold (upside down), used two oversized runners, some wide tapered gates, and a very fine commercial foundry sand with resin-binder.
The resin-bound sand produces a very accurate mold, and works extremely well with iron too.
Resin-bound sand is light years ahead of green sand in my opinion, if you need the accuracy, but resin sand is not easily reusable, so there is a downside.

I made a new pattern from steel after the balsa pattern broke up.
I also started using a ceramic filter above the basin (the basin is below the sprue).

The sprue is much taller than it needs to be, but I did not figure that out until later.

This one turned out better, and usable.

 

Fifth Base Attempt:

I was making two of the bases (one for a buddy), and I thought I could get away with not cementing the two mold halves together.
The mold leaked and I got a partial fill, and ruined what would have otherwise been a successful part.

 

Sixth Base Attempt:

I forgot to vent the high points of the mold, and so I got a large gas bubble, which basically ruined the part, although I could have filled the hole I guess (I don't like filler on a cast part).
But I did cement the mold halves together, but did not use any weights on top (a few weights on top are still required most of the time).

Still making dumb mistakes at this point, but definitely seeing some improvement in the overall quality, accuracy, and surface finish of the part.

 

Heat Treating Bases No.4 and No.6:

I decided to heat treat these two based in order to try and get a T-6 treatment, for better hardness and easier machining.
I had never tried to heat treat a part before, and I did not have my kiln electronic controller set up, so I used a Rube Goldberg arrangement on the kiln (crack the lid open enough to regulate the temperature to about 1,000 F).
This caused the elements to remain on all the time, and promptly melted the sides off of bases No.4 and 6.
Another really dumb move, and I was started to get pissed off at this point.
There was a very choice stream of profanity that emanated from my mouth when I opened the kiln, sort of like a long volcanic eruption sort of an utterance. Best not to have family and friends around when things like this happen.

I did the second stage of heat treating in the kitchen oven (much to the chagrin of the wife), and finished the treatment on one of the damaged based just to see how it would machine (very well, and much harder than untreated aluminum).

Many of these parts I ended up recasting, but I did use a few of them.

At least I had an accurate pyrometer for aluminum by this time.
But good equipment does not help if you don't know what you are doing.

I thought to myself "how many dumb mistakes do I have to make?"
An infinite number it would seem, (dumbness without limits). I should win a "most dumb mistakes with a single part" award. (no please, no cast "awards" in the mail).

 

7th & 8th Attempt:

I was making a pair of these castings, thus the reason for two bases cast.

By this time, I had pretty much exhausted every mistake I could possibly make, I had the technique down, and all the recast parts went flawlessly across about five pours in one day.

Here is base 7 and 8.
Turned out very well in my opinion, with no flaws anywhere, and these two bases are now used in two engines.

Notice the sprue height is much reduced.
I have since started using strips of wood on top the molds for dams, to prevent the vent runnoff spills.

I can pour aluminum in my sleep now, and never have problems.
I am still in the learning curve with cast iron, but I think I can sort that out this year if the economy will stop taking off like a Saturn V rocket (I have never had so much work).

 

One of the bases, with a partial rough assembly of parts.
I got it running on one cylinder, but still more machining to complete on many of the parts, and the second cylinder must be machined and added to the other side.

The flywheel is cast iron. One of two of my cast iron successes, amid a sea of cast iron failures.





This is a 60% scale model of this engine, built entirely from using three photos:
http://prestonservices.co.uk/item/oscillating-twin-cylinder-horizontal-workshop-engine/
And thus my 3D model avatar.
.
.
.

 

Yes, but the economy............it is going like the Saturn V rocket, straight into the stratosphere apparently.
I am at double the income from by previous best year, and only 7 months into the year.
I really don't know where it is going to top out at this point, I still have multiple projects due this year.
Its a roller coaster ride, but I need to make up for the abysmal 2008, 2009 and 2016 years I had, which were quite ugly.
Everyone I know seems to also be having a very good year.

I have been basically working almost 7 days a week almost since the beginning of the year I think, with a little furnace work mixed into that.

 

When the bugs are ironed out and it goes right, no bake resin bound sand is pretty awesome stuff. With the fine silica sand we used to use, I have seen fingerprints on the pattern release agent reproduced on the aluminium casting. It's getting hard to buy the resin here in Australia now so I may have to switch to sodium silicate: at least it can be made from supermarket items if push comes to shove.

Hopefully the work will continue to arrive: I have an uncle who designed power substations all over the South Pacific: they kept hiring him 15 years after retirement as his replacements kept having their work explode in a shower of sparks and flames.

 

Yes, well good in theory, but when running a one-man show, and an important client calls with a nice project, you don't say "no", else you lose an important client.
When two or three important clients call within a month, you still don't say "no" unless there is no physical way to get it done.
A number of people I know who went in business about the same time I did (2003) are now out of business and back in the proverbial and literal cubicle cell.
No way I am going back to the cubicle. I did that for 18 years, and got more than my fill of the Dilbert-book bosses and general lunacy.

But the good thing about working for yourself is that if you do twice the projects in one year, you can make twice the money.
If you do three times the number of projects in a year, you make three times the money.
So there is a direct proportion to hard work and time spent.
In cubicle life, I worked as long or longer as I do now, but always made the same salary.

I sent out a project early this year, and another one last month, and one today, so I am taking a break and posting today.
The remaining projects for this year are not due until next year, but I am afraid that if I kick back too much, then I will just get more projects this year, which will over-crowd next spring.

But by any measure, these are very good problems to have, so I am not complaining.
And when the economy drops back (sooner or later it will, it always does), then I can take off an extended period and get back to some real (and fun) work, like backyard casting.

 

Yes, I agree, the no-bake binder, especially the resin stuff, is the cat's meow, but it is quite difficult to find and purchase, and rather toxic without the correct respiratory equipment.
For these reasons, I am converting to all sodium silicate. No fumes, and I think at 3% I can probably mostly recycle the sand with a little washing and mulling.

I have one client who hires me a lot just to straighten out all his big box consultants out.
I would normally not help a big box consultant with anything since they are the competition, but the same client also gives me a lot of very nice projects, so I can't complain.
The big box companies seem to have so many incompetent engineers, especially electrical, and also especially industrial projects with medium voltage power and heavy controls.
They don't seem to teach those things in school it would seem, as least not from a practical design standpoint.

If the work stops coming at the end of the year, I will take a full year off, but I think there is a good chance things may continue upward for a number of years, due mainly to a lessening of over-regulation of industry, and political leanings in place now that favor business people like myself, and businesses in general.