The Bucket Foundry

[Flettner]

Baked sand cores? no need sodium silicate?

The Shell Sand process uses sand that has been pre treated with a heat activated bonding adgent.
The sand is designed to be blasted into a metal die, a very quick and accurite process. Experimenting like I do I just pour the sand into the die (It flows like water) then place it in the oven for a while. Slow but makes for a strong sand core. Useful with thin, intricate water cores.

[WilDun]

Baked sand cores? no need sodium silicate?

He has just changed from using sodium silicate, - it seems this resin sand will give better results (using heated metal dies) for core production .

[Michael Moore]

please show step by step how to heat treatment this part.

This will give you a good idea of the process:

http://www.eurospares.com/graphics/m...IL-H-6088G.pdf

I've done a few pieces at home and it is a long, all-day process. Unfortunately it doesn't seem to be an exact science, because the times/temps listed by various references can have a fair bit of variation. The time given as needed for soaking once solution temperature is reached may easily vary several hours depending which reference you look at. My friend Jeff's cylinders were soaked for just under 7 hours at 1000F, quenched in 208F water (the temp of the quench is important too) and then aged for 7 hours at 310F once the oven temp had dropped (which took about an hour). Jeff said they were very nice to machine.

cheers,
Michael

[Flettner]

Here we go, first shot, 1 x Shell Sand core.

[ken seeber]

Seeing Fletto is charging ahead with the shell cores, I thought I’d just show a little core I also made using shell. Essentially it’s a little core strip that supports a link and Ø5 cross pin. The pin will be cast in into the final product with the link being free to move about after the core is removed. Note the shell cylinder core in the pic, this is over 20 years old and still as good as new.

So, a simple block was made up, plus a bottom to stop the dry sand escaping when filled from above, when cold. A paper clip was used to hold the link central and vertical when filling.

Then it was a simple matter to stick it onto a small gas burner til the sand went a golden drown and wait for it to cool. First couple didn’t release successfully, so I wacked a series of M6 screws into the back to use for ejection.

Not perfect, but good enough for the prototype nature of the job.


Note the clean fingernails.

Now here’s a thought. CO2 sand is convenient, but not nearly as strong as shell sand. Shell cores are good, but require metal coreboxes to take the heat required, say around 200 C. Wot if one both mixed the sand with the sodium silicate plus the resin for the shell core? Set off the and with CO2 in plastic/timber boxes. Remove, then bake to achieve the shell qualities. Could be total crap with mixing of different chemicals, but it’d be nice if it worked.

[WilDun]

Now here’s a thought. CO2 sand is convenient, but not nearly as strong as shell sand. Shell cores are good, but require metal coreboxes to take the heat required, say around 200 C. Wot if one both mixed the sand with the sodium silicate plus the resin for the shell core? Set off the and with CO2 in plastic/timber boxes. Remove, then bake to achieve the shell qualities. Could be total crap with mixing of different chemicals, but it’d be nice if it worked.

Well, I believe the place I was talking about did just that, I remember a guy in the foundry telling me that they did use sodium silicate in the sand and that they cured it by heating it - I thought that they might be using shellsand (judging by colour) and possibly he didn't really know ..... now, I think that they could have been using that very combination!
Think the metal dies might really be the best way to go (except for a one-off!).

Good to see you back Ken.

[Frits Overmars]

Note the clean fingernails.

I did. I also noticed that your forefinger is longer than your ring finger, which normally is only found in the female species of the human race.
Good to have you back so I can pull your leg again Ken .

[WilDun]

I did. I also noticed that your forefinger is longer than your ring finger, which normally is only found in the female species of the human race.
Good to have you back so I can pull your leg again Ken .

Yeah, pull your finger out Ken!

[ken seeber]

I did. I also noticed that your forefinger is longer than your ring finger, which normally is only found in the female species of the human race.
Good to have you back so I can pull your leg again Ken .

Frits & Willy, jeez you’ve even got me questioning my sexuality: am I straight or am I a closet LGBTI? Scary really. Probably the best advice I can give is for all is to stand well clear of me…

So, whilst I’ve got your attention Frits, I have a question related to squish % area. In a homogeneous charge engine, what would be the downside of having a squish area of 60 – 70%, this being in a low BMEP application, say 100 cc, 3kW output @ 5000 rpm. Detonation? Poor HC emissions due to a quenching effect? Obviously set with a min’m squish clearance. I know it's an ESE question really, but with today's confused world....

[Frits Overmars]

Frits & Willy, jeez you’ve even got me questioning my sexuality: am I straight or am I a closet LGBTI? Scary really. Probably the best advice I can give is for all is to stand well clear of me…
So, whilst I’ve got your attention Frits, I have a question related to squish % area. In a homogeneous charge engine, what would be the downside of having a squish area of 60 – 70%, this being in a low BMEP application, say 100 cc, 3kW output @ 5000 rpm. Detonation? Poor HC emissions due to a quenching effect? Obviously set with a min’m squish clearance. I know it's an ESE question really, but with today's confused world....

ESE questions are not necessarily easy to answer, but let's have a go.
Persuading a 100 cc 3 kW rpm engine to detonate requires some serious labour. You could try 50° ignition advance, a heat range 5 spark plug, blocked cooling
and 50/50 petrol/diesel fuel .
If you minimize the squish clearance to its minimum, quenching would be limited. Scavenging the combustion chamber might suffer because the wide squish band counter-acts decent loop scavenging, but with the power you quote, that won't matter much either. I can't really think of one clear disadvantage, so just try it and let us know.

[Michael Moore]

I thought that a long finger like that was a sign of lycanthropy.

In olden days cores were made with things like molasses as a binder and were baked afterwards to harden them and that may be getting revisited in modern times:

http://citeseerx.ist.psu.edu/viewdoc...=rep1&type=pdf

cheers,
Michael

[Frits Overmars]

I thought that a long finger like that was a sign of lycanthropy.

I had to look it up: https://en.wikipedia.org/wiki/Werewolf
If what you suggest is true, we can come to the conclusion that wolf-man Ken was civilized enough to shave the back of his hand before taking that picture .

[WilDun]

I had to look it up: https://en.wikipedia.org/wiki/Werewolf
If what you suggest is true, we can come to the conclusion that wolf-man Ken was civilized enough to shave the back of his hand before taking that picture .

Closely parallels the hatred of the innocent two stroke engine, by lies being spread about by the dumb polititians whose minds have been poisoned by the great devil H**da (and others)! ....... can we save the two stroke? We must be in there quickly, before we forget what happened in the middle ages .... I mean, there is hardly a Witch or a Werewolf in sight these days and let's face it, the two stroke could also be relegated to folklore!
And to think, all this furore caused by poor old Ken showing his hand!

Getting back in the groove again,
https://www.youtube.com/watch?v=UPiF...OCmdH&index=29
I like this guy's style in the videos and much of the stuff he talks about is (to me) correct, but he can get it into words much better than I can!

The application for which a two stroke engine is being used is a very important factor though - in the case of light aircraft the modern two stroke is a winner, requiring more or less constant speed (RPM), a high power to weight ratio (very important in aircraft), but still requiring a relatively mild state of tune and of course simplicity in the maintenance department. Fuel consumption and pollution can probably be improved too with EFI.)
I think that these are the main things Neil is trying to achieve, but maybe I should leave that for him to discuss!

PS. - I decided to move over to the Oddball Engines and Prototypes thread because it was maybe getting a little off topic here

[ken seeber]

Well, had a lead casting experience this morning. Not even successful. The 50:50 sand/plaster mould had been indoors for the last few weeks and felt dry (my subjective perception anyway). Irrespective, I heated it to 100 C for about an hour prior to pouring.

Started off ok, but virtually immediately it started spitting back. With stupidity at hand, I just kept pouring hoping it’d stop. It didn’t, so the bulk of the metal in the small crucible ended up outside the mould. Opening it up revealed that it had sort of completely filled, but the casting surface was very heavily pitted and the once “smooth as a baby’s bum” plaster mould was quite eroded in spots.

Conclusions:
1. Bit of a pisser
2. I’ll give it a retry, I have another set of moulds (100% plaster, as it happens), but on the basis that the issues were a result of residue moisture within the plaster, heat it up to 250 or so for at least a couple of hours.

Anyone had experiences with plaster?

[WilDun]

Well, had a lead casting experience this morning. Not even successful. The 50:50 sand/plaster mould had been indoors for the last few weeks and felt dry (my subjective perception anyway). Irrespective, I heated it to 100 C for about an hour prior to pouring.
..............Anyone had experiences with plaster?

I have made a plaster/sand mould but as yet haven't poured it.
Saw a video quite a while ago - (Think it was in Alasca, it was dark with snow lying around) where the guy actually heated up the mould to a very dull red in his furnace (to burn out a pla printed pattern) - I couldn't believe that it could be done! - but it was entirely successful.