Things they dont tell ya when you start casting. :)

Home enthusiasts discuss their Foundry & Casting work.

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Lazz
Posts: 136
Joined: Sun Jul 29, 2012 11:06 pm
Location: The Warm Arizona Deserts... Phoenix to be precise...

Re: Things they dont tell ya when you start casting. :)

Post by Lazz » Thu Jun 06, 2019 12:27 am

Even more stuff no one mentioned about casting....

7) Buying casting parts and materials from Amazon can be iffy. Some great and lots of complete disappointments. Not to knock imported items.... But my Amazon Cheap thing record is poor to say the least... The mounting end of the thermocouple I bought to check temps melted on the first use. it said it was rated for 1300C. Its replacement shows it was effected by the heat.
The crucibles from Amazon were surprisingly good. Both the cheapest #4 and the #4 priced twice as much.... $18 something and $35 ish...
The recent propane regulator didnt work.
FYI Milton air connectors from Amazon can be complete trash.

8) A fluffer does not work well with petrobond. Olfoundryman of youtube fame makes it look like a necessity... If you use petrobond put your effort into a muller...

9) On the subject of a muller.... Casters might not be a good thing on the feet of a muller. Even locked they can allow the muller to move... The very things that allowed me to store the muller in a good spot did not have enough surface area to stop movement... They just slid without rolling. Funny and alarming all at once... I should have made a video...

10) Match plates are hard to make... and SO nice to use when they work... That is why people use them. Using match plates can lead to small internal leaks that can burn wooden flasks....

11) Lost foam casting in the raw makes for some nasty surface finishes.... Maybe with a coating it works better... my experiences were with items that the surface finish didnt matter. Also the sand can fall into the casting as the foam melts.

12) A casting that requires more material than your crucible holds can be done in multiple melts. Let me explain this... I needed a leather piston cup for a hydraulic pump.... This required a way to hold a 7" exterior diameter, 3" tall hunk of wet leather until it dried. Casting a 10 inch donut 4 inches tall took 4 melts for me with my #4 crucible. The best part is it worked really well.... Turning the donut in the lathe was worrisome at first. And I did have to bondo the interior to fix the many surface flaws. But it did the job....If surface finish is important this is not an option. This method did work while under compression.... BUT as I cut it up to reuse it did separate. I did a test run and laminated leather I have on hand. It worked. Since the cup is in a cylinder compressed around a piston delimination is not likely. This saved a Dake 70H from a trip to the scrap yard....

13) Petrobond changes with use... My petrobond has cast a couple hundred items.... It has gone from a orange sticky sorta paste.... to a black burnt grainy something.... If I had separated the burnt material I would not have any remaining sand.... Adding oil and alcohol does help... but the stuff Im using now is very different from new petrobond.

14) Where can you find useful information about petrobond care and maintenance. As of recently I have found a need for another 100 pounds of sand....Buying petrobond powder/clay and oil seems to be questionable at best... Commercial foundry suppliers offer petrobond 2 clay and oil to make 1000 pounds batches... Ebay has an offering of material to make 100 pounds. I have petrobond 2 and on ebay is material to make petrobond 1 can I mix them? who knows. The ebay seller doesnt answer. The seller I bought my original couple hundred bucks of sand from doesnt answer. And the internet forums I have asked are silent on this subject.... Are these some of the reasons the people Im learning from on youtube these days do not use petrobond... they use greensand.

Thanks to all that read this... and please comment...

Harold_V
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Location: Onalaska, WA USA

Re: Things they dont tell ya when you start casting. :)

Post by Harold_V » Thu Jun 06, 2019 1:52 am

Interesting comments on petrobond. I am aware that it is expensive, and appears to have a "cult like" following, especially considering most folks don't use their sand daily, so greensand isn't a great option. Wish I had some experience so I could share what I might know with you.

That said, because I intend to pour iron, I'm thinking I'll head in the greensand direction, likely with something like olivine, so should I desire to pour steel or stainless, I'll have the recommended sand. I'll still have the same problems others have, however, in that I won't use my sand daily, so it will most likely need to be conditioned just prior to any attempts to do some casting.

Thanks for posting your thoughts. I enjoy hearing the experiences others have, and hope to be able to share mine in the future.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

RONALD
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Re: Things they dont tell ya when you start casting. :)

Post by RONALD » Fri Jun 07, 2019 6:26 pm

As I wrote in previous posts, I started with greensand in the night school class I was attending, and then when we switched to the other shop with Petrobond, I was convinced it was for me. I used that shop exclusively for many years, because I had a special permit even tho the night school had long been closed.

In the 90's, when I got hold of what was left of the closed shops, I did not bother to move the Petrobond, but bought bags of PetroBond II from a distributor. I had bought 20,000 pounds AFS Wedron 105 sand in the 80's and still had many bags stored in the school when I took early retirement in 1994. I got students, for extra credit of course, to move those bags, several each day, into my Suburban; I took it all home!

So, I have lots of stored sand, and I mixed up, in one of my Simpson Mullers, ~ 1500 pounds of PetroBond II ~ in 2000.

Great stuff, use it all the time, thro away the real burnt stuff and mull every couple of months. I use a a great deal of that AFS 105 sand for the Sodium-Silicate/CO2 Process, and with that process, the sand is not recoverable after one use. It's too difficult to recover, cheaper to thro away.

As far as Information is concerned, there is not much knowledge on mixing the two, as you found out when you got zero replies on Alloy Avenue.

I was surprised to find out, on the Internet, I could not acertain who now produces PetroBond 1 & 2. Used to be the Bentonite Corp.

I have no need for any now, what I have will outlast me.

As I wrote before, you may be the first to mix the two - try it!

reubenT
Posts: 96
Joined: Wed Dec 24, 2008 11:04 pm
Location: Spencer TN USA

Re: Things they dont tell ya when you start casting. :)

Post by reubenT » Fri Oct 25, 2019 11:49 am

I hauled in my own sand with a dump truck from a sand quarry. several tons for less than $100. including fuel. I think it was $8 a ton, I'm sure it's a good bit more now. Mortar sand from a building supply works good. It should be mined sand from sandstone, not beach sand or wind blown sand. The grains need flat surfaces to stick together good, if the edges are too rounded from agitation it won't hold together very well. Then some bentonite clay from a well drillers supply. I think it was 10% clay powder to 90% sand, (or was it 20% clay? I'd have to check the book again) mixed and moisturized just enough to make it clump when squeezed. It has to be mixed with a smearing action between two surfaces to get all the sand grains coated with clay. That's a lot of work with a hand hoe. Which is where the power sand mauler comes in handy. I made my own from scrap stuff. But if ya only want a few gallons it's not worth getting the power device. Just smear it under a hoe a few ounces at a time against the bottom of a wheelbarrow.

A light steel food can can work to melt aluminum, but not a good idea, it'll melt through with second or third use an loose the load into the furnace. better to use a heavier steel can. I made one by welding a steel plate on one end of a 4" dia by about 10" lone piece of steel pipe, 1/4" thick. and it's held up for a long time now.

One thing I wasn't told but quickly discovered. I can just cut up chunks of dry wood to under 3" or so, use them for aluminum melting fuel. I got a steel Freon jug and cut the top off, Any metal container of around 5 gallon size works, using a 50/50 fire clay sand mix to line the interrior. or even just dig up some clay and make a pot of it, need a 3-4" pipe going into the bottom with a blower on the pipe. Anything that will move air works. Like a hair dryer. Too much blast will blow charcoal out of the fire, just a light blast will do. I set the steel can in there against the opposite wall from the blower pipe, start a fire and turn a low blast on. drop in more chunks of wood as they burn up. A top on the furnace with hole over the crucible helps direct the heat around the can.

The books cover all the basic stuff. If'n ya wanna get into it, just round up several books on the subject and read up. Too bad Lindsey pub had to go out of business, they had a lot of good books on all sorts of old technology. At least I was able to buy most everything they had I was interested in before they shut down. Astragle press has a much larger selection now. And Google books has digitized a lot of old ones. I found one there on foundry work and furnaces from over 100 years ago, and it had a little info on charcoal foundry.

Harold_V
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Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Things they dont tell ya when you start casting. :)

Post by Harold_V » Fri Oct 25, 2019 3:59 pm

reubenT wrote:
Fri Oct 25, 2019 11:49 am
A light steel food can can work to melt aluminum, but not a good idea, it'll melt through with second or third use an loose the load into the furnace. better to use a heavier steel can. I made one by welding a steel plate on one end of a 4" dia by about 10" lone piece of steel pipe, 1/4" thick. and it's held up for a long time now.
Before making the decision to use steel as a crucible, consider whether you hope to achieve acceptable results, or not. Molten metals are STRONG solvents of other metals. Molten aluminum dissolves steel (the charge does NOT "melt through", as you don't come close to the melting point of steel) contaminating the aluminum. Is that the result you hope to accomplish? If not, either learn to coat the steel vessel with a refractory, or abandon the use of steel in favor of the use of proper crucibles.

Please note that I did not say that you can't use steel vessels. It's obvious that you can----but should you?
H
Wise people talk because they have something to say. Fools talk because they have to say something.

reubenT
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Location: Spencer TN USA

Re: Things they dont tell ya when you start casting. :)

Post by reubenT » Mon Oct 28, 2019 8:00 pm

I do because it works, and I'm not making critical stuff. Just hubs and pulleys usually. Serves my purpose very well. But if in finer work or where exact alloys are critical, might not be so good.

Why is green sand not so good for infrequent use? I've been fine with infrequent use. Just screen it and add a little water to bring it back up to the right moisture level. Of course I intend to start using it with iron before too long.

Harold_V
Posts: 17739
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Things they dont tell ya when you start casting. :)

Post by Harold_V » Tue Oct 29, 2019 1:51 am

I can address the use of sand strictly from what I've read. I have yet to use it personally, although, with a little luck, that will change in the not too distant future, as I am near completion of the setup of my induction melting system.

That said, you've already addressed the problem with infrequent use of green sand. It doesn't maintain the necessary moisture, so that would have to be addressed. I suspect, especially after reading your comments, that it's not much more than a small inconvenience. Adding moisture and riddling should restore the sand, in short order, to being useful. When it's used daily, I suspect that's not an issue, although there must be at least some drying on weekends, especially long weekends.

In regards to aluminum melting in steel vessels, there's alteration of the chemistry of the charge. That's the problem, and it has the potential to destroy the desired qualities of the metal. Only you can determine it that's important to you, or not. From my vantage point, it's just one more of the things that can (very easily) be avoided that can be troublesome. That's the thing that readers need to glean from this conversation. They deserve to know that it's not a good idea, no matter that it works. You can park your car in the garage by driving through the closed door, too, but should you? :-)

H
Wise people talk because they have something to say. Fools talk because they have to say something.

reubenT
Posts: 96
Joined: Wed Dec 24, 2008 11:04 pm
Location: Spencer TN USA

Re: Things they dont tell ya when you start casting. :)

Post by reubenT » Tue Oct 29, 2019 4:20 am

I'm not a perfectionist on alloys, don't care if something is off a bit as long as it works for what I need it to do. Perfectionism has it's place in critical jobs.

After foolin with it a number of times I get a feel for how much moisture the sand needs. Get too much moisture and it can't escape fast enough and bubbles back up through the metal, usually ruining the part but not always. Get the right amount and it sticks together nice for the form without steaming off excessively when poured, of course good venting is needed around the form. The last pour i did was two bell shaped aluminum parts, didn't vent the inside of the first one and it bubbled a bit on top, part was still usable, second one I vented the inside out the bottom and it poured nice. The sand knocked off the part is dried out of course, and then if it sits in the open it dries out. But if I keep it in closed buckets it holds moisture and usually needs very little added.

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