The Bucket Foundry

[WilDun]

This was cutting edge foundry gear back in the sixties, (modelled here by Trev Tosser ) - note the fireproof black singlet, the casting shorts, gumboots (leather?) and the protective hat - unfortunately back in those days gloves and face shields were not mandatory! (they were for Sheilas).
Why leather gumboots? well rubber tends to smoke a lot and attracts attention!

[WilDun]

. I remember seeing a guy using HF acid, I said do you need gloves, he replied, if you need gloves, you are splashing the acid about.
Neil

I also worked with a guy who, when he first started and didn't understand our do's and dont's, went to the sink in the workshop( the same sink where we cleaned up the welds on S/S with hydrofluroric acid) and he saw the jar of clear gel and assumed it was hand cleaner.
He came and said to me "geez mate, that's pretty strong hand cleaner you've got" but he did wash his hands with it and luckily for him it's very soluble in water and he had rinsed it off reasonably quickly! It didn't really give off any warning like burning of the skin, but did give off some fumes.
I'm reliably told it can penetrate to the bones without hurting the tissue.
Seems it didn't do him any harm, but definitely not recommended for hand washing!

[Lightbulb]

The real lesson for me was to really think about what I was doing, and develop a method that makes the process as safe as possible. HF is weird stuff.
They put some on an old pair of jeans, let it sit there for a while, then washed them. After repeated washes, the material kept on rotting a bigger and bigger area every month. Just incredible to see. A lot depends on the initial concentration of the HF.
Some processes are just inherently dangerous and even the most cautious can get caught out by basic things like the weather changing and rising humidity leaving a layer of moisture on the surface. We always mixed fuel when the humidity was the lowest for the day, usually around 12-2 pm.
We avoided where possible mixing fuel on rainy days.
Neil

[WilDun]

Some processes are just inherently dangerous and even the most cautious can get caught out by basic things
Neil

Yes, as you say we can get caught out by basic things, but nearly always in the heat (no pun intended) of the moment, either through being unfamiliar with the process at the time, or at the other end of the scale, being "blinkered" by familiarity and the "that won't happen to me" attitude, (guess I'm basically talking about myself here!)

Flettner said "dumb and dumber" but I don't think it's got anything to do with being dumb, - more to do with being enthusiastic really!

[Frits Overmars]

Flettner said "dumb and dumber" but I don't think it's got anything to do with being dumb, - more to do with being enthusiastic really!

I think Flettner was right. How else would you describe failing to keep yourself in one piece?

[WilDun]

I think Flettner was right. How else would you describe failing to keep yourself in one piece?

It's just lack of care or practical knowledge and is usually called 'ignorance' which is easily cured, but lack of brains (often mistakenly called 'dumb') can't be cured. - Of course there is sometimes the odd case where both are present That's the one to worry about. - Then would a "dummy" be into motorcycles or metal casting? - of course not! ...... well possibly not.

[WilDun]

Flettner,
I'm working with wood and glue at the moment trying to make small patterns,(after a long spell of dramas with grandkids etc.)

I think I've found a good turning wood - don't really know what it is and I don't have much, but it turns very well anyway!
Because the things I am casting will be quite small, I've decided to try the Sodium Silicate/Co2 method for both pattern and coremaking - I can't afford to have any slight collapses of the mould and my reasoning is that it looks like it holds together well.

I have also been going over that stuff on page 15 of this thread where you talk about making coreboxes using casting resin for the corebox and am interested in the bit about trimming back the resin to produce a half mould, then casting the resin over the (replaced) vinamold pattern.
What I really need to know about the process is, do you take it down with a flycutter or mill - ie is the resin easy to machine without it chipping?
What sort of wax do you use between the halves before pouring the top half - is it sprayed or brushed on?

Any tips here welcome as this is all new territory for me!

[ken seeber]

Willy,

My experiences are limited with resin against resin, but the few small coreboxes we have done, mainly with fibreglass, 3D printed ABS and 2 part polyurethane, we have used various release agents: silicone spray, Mr Sheen, fibreglass style release agents and they also seem to work. I'm sure Fletto can offer much more useful info though.
As for CO2, we did some initial trials ages ago using a disposable SodaStream canister. Good for piddly sized things without the hassle of bottle rental etc. Another source we also thought of was CO2 fire extinguishers. Over here, with all our "do gooder" health and safety public servants, there are rulings on these, such that they must be serviced (??) etc or replaced at time intervals. Replacement is cheaper than servicing, meaning there are perfectly good extinguishers going to waste. The inspector guy told me that we had to dispose, or certainly not use, the replaced ones (even though they show full pressure). So, I have them in a corner with a sign on them "In case of fire, do not use"....just watch the place burn down instead.

[husaberg]

Neil wil be along soon to give you the good oil
But he uses Graphite powder in this.

[WilDun]

Willy,

My experiences are limited with resin against resin, but the few small coreboxes we have done, mainly with fibreglass, 3D printed ABS and 2 part polyurethane, we have used various release agents: silicone spray, Mr Sheen, fibreglass style release agents and they also seem to work.
As for CO2, we did some initial trials ages ago using a disposable SodaStream canister. Good for piddly sized things Another source we also thought of was CO2 fire extinguishers.

Just having another quick look on the way to bed (fell asleep on my chair after watching the Moto GP at Brno)
Most of the stuff I'll be doing is 'piddly' size and I have a Soda Stream with an exchange cylinder raring to go! When I visit the scrapyard there is usually a skip full of 'expired' Co2 bottles, maybe good material for casting - I dunno.
Never thought I would keep up the enthusiasm like I have done - five years ago I thought I was stuffed, or at least more or less incapacitated for life, but you just never know!). I do have to keep pushing myself every now and then. Making this all public also makes me keep trying in order to save face! - and ......look at all the people you meet on the way!

Husa,
That video I think was done in the commercial foundry he used previously, and everything being done there is huge compared to the stuff I'm hoping to do, so there will be a few subtle differences.
I think Neil uses graphite between the main moulding flasks now, but I'm talking about making resin coreboxes for tiny cores - graphite might do of course, but I'm pretty sure he uses spray on or brush on wax for that purpose. - we'll see....

[husaberg]

Just having another quick look on the way to bed (fell asleep on my chair after watching the Moto GP at Brno)
Most of the stuff I'll be doing is 'piddly' size and I have a Soda Stream with an exchange cylinder raring to go! When I visit the scrapyard there is usually a skip full of 'expired' Co2 bottles, maybe good material for casting - I dunno.
Never thought I would keep up the enthusiasm like I have done - five years ago I thought I was stuffed, or at least more or less incapacitated for life, but you just never know!). I do have to keep pushing myself every now and then. Making this all public also makes me keep trying in order to save face! - and ......look at all the people you meet on the way!

Husa,
That video I think was done in the commercial foundry he used previously, and everything being done there is huge compared to the stuff I'm hoping to do, so there will be a few subtle differences.
I think Neil uses graphite between the main moulding flasks now, but I'm talking about making resin coreboxes for tiny cores - graphite might do of course, but I'm pretty sure he uses spray on or brush on wax for that purpose. - we'll see....

I'm Confused. your post specifies CO2 Sodium Silicate?

[WilDun]

I'm Confused. your post specifies CO2 Sodium Silicate?

My intention is to use sodium silicate in my moulding sand hardened with Co2, and also to use the same material for the cores. The main pattern can be made of wood of course, but the core (in my case) really needs to be moulded in a corebox. The corebox can be made by pouring a casting resin around an internal cavity shape. This shape is formed by pouring Vinamold into the cavity of an original example of the cavity you hope to reproduce, the copy then becomes a positive of the cavity shape, made of Vinamold - in effect a rubbery plug which can be relatively easily removed.

This Vinamold positive is then suspended by a suitable wire or long screw (which has been cast into the vinamold) in a suitable container and casting resin is then poured around it, which hardens. The Vinamold plug is then removed leaving a block of resin with a copy of the desired cavity in it.

In order to use it to make (rigid) sand cores, it now must be capable of being split into two halves so this rigid core can be removed.
To achieve this (as I understand it) Neil cuts (flycuts? mills? carves? - that's what I'm looking to find out) half of the resin corebox down to a parting line at exactly the widest part of the cavity.

The Vinamold plug is replaced in the cavity of the remaining part of the resin block, which is then set back in the container again and the top of the resin is coated with some sort of wax (sprayed on? brushed on?) and then filled up with resin again. When that has hardened, a two piece corebox is the resutl - this can then be used to produce any number rigid sand cores.

BTW. That is the process as I see it, - Neil, can you please correct me here and there where necessary? - maybe you could also tell me about the machining of the resin and the type of wax to use. - thanks.

Hopefully I've got it sussed - I'm going to try it very soon!

[husaberg]

My intention is to use sodium silicate in my moulding sand hardened with Co2, and also to use the same material for the cores. The main pattern can be made of wood of course, but the core (in my case) really needs to be moulded in a corebox. The corebox can be made by pouring a casting resin around an internal cavity shape. This shape is formed by pouring Vinamold into the cavity of an original example of the cavity you hope to reproduce, the copy then becomes a positive of the cavity shape, made of Vinamold - in effect a rubbery plug which can be relatively easily removed.

This Vinamold positive is then suspended by a suitable wire or long screw (which has been cast into the vinamold) in a suitable container and casting resin is then poured around it, which hardens. The Vinamold plug is then removed leaving a block of resin with a copy of the desired cavity in it.

In order to use it to make (rigid) sand cores, it now must be capable of being split into two halves so this rigid core can be removed.
To achieve this (as I understand it) Neil cuts (flycuts? mills? carves? - that's what I'm looking to find out) half of the resin corebox down to a parting line at exactly the widest part of the cavity.

The Vinamold plug is replaced in the cavity of the remaining part of the resin block, which is then set back in the container again and the top of the resin is coated with some sort of wax (sprayed on? brushed on?) and then filled up with resin again. When that has hardened, a two piece corebox is the resutl - this can then be used to produce any number rigid sand cores.

BTW. That is the process as I see it, - Neil, can you please correct me here and there where necessary? - maybe you could also tell me about the machining of the resin and the type of wax to use. - thanks.

Hopefully I've got it sussed - I'm going to try it very soon!

First page.

The bag of sand ( in the picture ) is the shell moulding sand I talk about. It is suppiled with a resin coating, this bonds to itself at approx 180 degrees C. You will need a metal die for this ( and the wifes oven ). Some of my dies are made using the CNC but some are made by copying the wood / bondifill moulds into aluminium at the foundry, then turning them into dies. This works well although they do need a little cleaning up so the sand core will slide out easily. I have a few pictures, I'll round them up if you like.
The other stuff in the pictures is the casting resin, for pattern making. It is good because it doesn't shrink or expand as it sets. It uses two equal parts. It is expensive at $380 for what you see here, adding micro ballons makes it go a little further. I have tried other products but at the end of the day this stuff is worth the money!
Good on you for having a go, I posted these pictures of making a cylinder ( pattern making ) so others might have a go instead of trying to hack out old cylinders to make them what they never were ment to be. Having the ability to cast intricate parts ( cylinders ) changes the way you will approch projects.
You will need a temp probe, I made one useing a cheap meter I bought using I think type K wire. Put it inside a stainless steel tube with the bare wire sticking out the end. There is quite a bit to melting alloy properly as you will need degassing pills and a flux of some sort.
After we had the " incident " with our home foundry I decided it was better to be friends with a local foundry and let him melt the alloy for me, I just make the moulds and put them on the floor next to his moulds.
The white sand you see is CO2 hardening sand ( cold process ), just pack it in then apply CO2 gas and will harden up instantly. This sand is not as strong as the shell hot sand process but it's good for less inticate parts. I'm not sure what is mixed with the sand, Husaburg will know.

Then after pouring a mould I cut and changed the shape to the curve I wanted

Click on the arrow after Fletner
Note you will not need to make the aluminium die if you are gong to use CO2 sand but you might run into problems with the gas not being able to escape so do plenty of vents.

[WilDun]

First page.



Note you will not need to make the aluminium die if you are gong to use CO2 sand

Husa.
I did (at one stage of my employment) make cast iron coreboxes to be used for the resin coated "shellsand/coresand". These were for the Masport Foundry (ie used for the fluid valve castings, which they made for us) and that's when I got really interested in the foundry process.

However, I won't be using this core sand because:-
(1) it stinks,
(2) it smokes,
(3) it requires metal patterns and coreboxes,
(4) it's not really suited to a small home workshop in a residential area, as is my situation.

Don't get me wrong though, it's a very good process and is used by just about every good foundry anywhere in the world, it's just not for the 'piddly' stuff that I and others like me will be making !

Thanks for all the research you do, I'm afraid I'm a bit slack about going back through long threads, - there is (in my opinion) something to be said for starting new threads when the direction of the thread changes to another subject entirely (and it often does), but I don't think everyone would agree!
That would sure help though, eg. for those who are intent on learning stuff, as opposed to light discussion, (which I also enjoy BTW).
Guess it's hard to separate the two though........

[Flettner]

I'm building a new cylinder (sick of all the old half made ones)so here goes, glueing bits of armorboard together to make a male shape of the bore and ports. Finished bore will be 50mm so I've made this round center section 47mm, allowance for machining. I've cut sections out where I want to glue in male port shapes. What I'm building here will be used to make a multi piece female copy that will finish up being the sand core box ,to make sand cores and also used to make the inside part of the cylinder mould. What I'm build here will only be used once when it's done it's job it will go in the bin, the female copy of this will be used ongoing.