Casting Advice (no laughing please)

I would not worry about surface cosmetics too much.

That can be resolved over time.

If you don't control the metal velocity as you pour, you will get splashing, air aspiration, mold degradation, sand washed into the molten metal stream, etc.

Think of pouring metal like pouring a beer.

If you pour a mug of beer from a tall height, from straight above, you get a multitude of splashing, foam, etc.

If you pour from the lowest height possible, sometimes resting the lip of the crucible on the top of the sand mold, then you get a much more smooth pour.

Scraped ways on a lathe have an introduced surface defect, and that does not affect the performance of the metal, so it is not out of the question to use castings with surface defects.

I have tried various methods to stop the lid leak, and found it impossible.

The lid leaking will not affect furnace performance.

The total amount of combustion air being forced into the furnace will equal the sum of the gasses exiting the furnace lid and the gasses exiting the lid joint.

No big deal; all lids leak. Just ignore that.

.

Luker

I see, thanks.

I think I have realised that I’m barking up the wrong tree with this particular part, because of shrinkage. It’s actually supposed to be a precision part, with the arcs on the picture being 60° of a 2 inch circle, plus and minus 15 thou for sandpaper. The reason I wanted to cast it, was because I couldn’t see a way to machine it with the machines I have. But casting just isn’t gonna give the accuracy I need. We live and learn!

Never mind, I have another pattern printed for a different thing, a stamp for wood.

I am determined to crack this though, so many possibilities open up if one can cast parts then machine them.

I think what I’m going to do, is order some proper greensand from sdts (actually not as expensive as I thought) then I’m off abroad for work for a couple of weeks, then I’ll come back to it.

Thanks for your help

thanks for your help

Cheers

Steve

Posted by Steve355 02/07/2022 09:54:21

Morning

Is there anyone out there who has advice for a total beginner at sand casting?

I made a waste oil burner and furnace, after a lot of tinkering it’s working pretty well and can
get up to 1100 deg C or so without too much trouble.

My first project is to make some brass sanding blocks for making woodwork moulding planes.

I made a pattern on a 3d printer. I used play sand (fine and consistent) and about 10% fireclay
as DIY greensand.

I used a cast iron flask, packed down the pattern in the sand vertically and removed it carefully.
I melted down the brass and poured it in. The result was, well, roughly the right shape, but it had
a big nodule on the bottom (presumably caused by the pouring brass) and a terrible pitted finish.

of course I can sand out some of the pitting, but that’s not the point.

Does anyone with experience have any tips? See pics. Yes it’s terrible, I know.

Steve
---------------------------------------------------------------

I started casting around 1984 ,i was at a Model engineer show and one of the stands
was selling crucibles along with give away leaflet , i bought one i think it was about tenner.

That was about as much as i knew about casting,back then there was no internet and
there was no one that i knew of that had done any casting,first problem no sand, i had a ring
around after looking through the Yellow pages most of these were industrial type suppliers
and came with the warning of the usual that's too dangerous you'll end up killing yourself
(much the same as you often see on this forum), we only supply 20 tons at a time.

I phoned around some local foundry's and they were most helpful ,bring some buckets
and you can have some ,i still have the same 2 dustbins full of sand now.

My first castings were done using an old tin oil drum full of coke and an old cylinder
vacuum cleaner to provide a draught, some of the early castings were nothing more than
useful blobs of metal but you learn as you go along.

Eventually i got fed up with the tin can and coke furnace and built this modified Dave
Gingery furnace (in about 1989) supposedly will melt 20 lb of cast iron in 45 min i don't know if it will
I've never tried it with iron , an A8 crucible will fit inside.
(First Photo)

The thing is when you have done some of this you tend to forget how much equipment
that you have accumulated over time, the furnace the crucible some sand and then all of the other
stuff that you need lifting and pouring rings , moulding boxes, patterns and some
decent safety equipment and so it goes on ,it all adds up to some expense in both
money and time.

The 2nd photo here shows some of this stuff in the foreground some moulding boxes,
crucible , lifting tongs, pouring rings , behind , a copy of Luckygen's sand muller a recent
addition ,at the back leather aprons leggings face shields and gloves.

I don't do much foundry work the last time was about 15 years ago but in the next week
or so its getting fired up again if the weather stays fine. 3rd photo.

It should be much easier than when i started as there is so much stuff available now and
useful advice , there's Luker, Pat J, and Noel Shelly ,worth looking at the videos
from Luckygen ,Old foundry man and Myfordboy they will all have something that
will be of use to you.
You just have to stick with it ,work carefully follow some of the advice and watch some
of the videos .

John

And don't forget the books on casting by Terry Aspin (Chuck) the venerable Foundry work for the Amateur and the updated one in the Workshop Practice series.

I know very little about sand casting so forgive me for intruding but in general terms, I found out many years ago that it is a big mistake to buy cheap when learning (anything) and will cost you much more in the long run.

(In my case it was as a teenager learning to process/print photographic film. It never worked right until I started using first rate materials rather than the surplus/outdated stuff that I was trying to learn on. Never forgot that lesson.)

I buy my sand, sodium silicate, bentonite and ingots from Artisan foundry supplies. They are based in Liverpool here in the UK. When I first started casting I was given some greensand and bentonite by a local engineer. Before that I bought fine sand from B&Q and used cat litter which in some cases is mostly bentonite. It was all a waste of time. This photo is of a small oval name plate I made for the engineer. I made it with his greensand/bentonite and cast it with a zinc/aluminium alloy. The letters are 8-ishmm in height and protrudes from the surface 2mm. You can see the layer lines from the 3D print.

Edited By lee webster on 02/07/2022 22:53:52

Lee, that’s really impressive. Quite similar to some projects I’d like to do.

I was looking on the Artisan Foundry site. I see they have “Bromsgrove” greensand. But it isn’t clear if this is all that’s required or if it needs additives. What products do you use from their site?

Steve

Steve, I buy the Bromsgrove sand from them in a 25kg bag. I spread it out on a tarpauline in my conservatory to dry it for a few days, then use a flour sieve to remove all the bits bigger than fine sand. I loose about 2 to 3 kg of unwanted content. I then weigh the sand exactly, and seperate out one kilo. I add a small amount of water to the kilo, but not enough to make the sand wet. Very bad! This is why I do this with just one kilo, I am trying to determine how much natural clay is in the sand. With my last bag of sand I had to add 10% of bentonite before I felt happy. When I have the right mix, I can add bentonite and water to the rest of the sand which is then given a good whisking and is kept in a sealed container. If I haven't used the sand for a few weeks some of the water will have evaporated. I add a bit more water using a small spray bottle, give it a good mixing using something like a paint stirrer on a battery drill, and let it sit for several hours before using. If the sand is too wet I just leave the top off the container for half a day, stirring the sand now and then. If I have something like the name plate to cast, I will use a very fine sieve, finer than the flour sieve, to cover the surface with a thin layer of smaller grains of sand. Then I will use the flour sieve for put in 20-ishmm of sand, then just shovel it in to the top. I usually ram, not too hard, when the flask is about half full, then proper hard ramming when full. I allways pile the sand on high before ramming. I haven't got a muller for sand preparation, I just use the paint stirrer (home made) to fluff up the sand after each pour. Olfoundryman, Martin, and Swdweeb, Perry, on youtube are good people to watch. Martin is a proper pro, Perry is self taught and produces excellent results. Martin uses self prepared greensand and his surface finnish is second to none. His work makes my name plate look like it was made with a bag of boulders!

Lee

Edited By lee webster on 03/07/2022 08:41:14

Damn, I was hoping the bromsgrove sand might be a ready to go mixture, but if it has large bits in it, random amounts of bentonite, etc, I wonder what’s the difference between that and any other sand!

What sieve/riddle did you use? Do you know the grade by any chance?

These Foundry posts have really got going ! I started with about 100Kg of mansfield sand in 1995, I'm still using the same sand, I added nothing - but water ! It is stored in an air tight plastic bin and is ready for use at ANY time. Molds are broken open straight into the bin a little water added and it's ready for next time ! Parting powder to stop the sand sticking to the pattern, buy proper or use talc, perfumed or not to taste ! To administer make or for £3 buy the the proper bag. A flour sieve is good to put the faceing on, say 3/8"deep, then shovel half a box full and ram, a rammer can be almost anything, I use the handle of a 4Lb lump hammer. Then fill and ram above the sides of your mold box and strike off flat with any straight edge - hacksaw blate, steel rule, bit of wood Etc Once made the mold will last almost for even, I have an impellor mold I made about 10 years ago, not got round to casting it - yet. For those with welding gear the easy way to make mold boxes is to visit a scrapyard and buy a length, say 3' of LARGE box section, 100 x 100 x 6 upwards to say 500 x 150 x10 and slice into 2" or3" thick slices, weld on 10mm round bar handles and locating bosses for the pins, eg 20mm box 1" long, pins to fit and a T handle on top. The weight of the boxes is important as the metalastatic force of the molten metal will "float " the cope off with even small castings, even so added weight on the top of the cope WILL be needed I use lead ingot cause I have them ! COPE (worn over the shoulders) = TOP ! DRAG, (what we do with our feet ) = BOTTOM- simples ! ONLY POUR MOLDS ON A SAND FLOOR, or a sheet of dry timber NEVER NEVER on concrete, stone or gravel, ignore this simple point and you may findout what it's like to stand over a grenade when it explodes and the shrapnel may still be molten !!!!!

I will try to add a photo, the date shows it was made not long after I had started the foundry, and we would do steam rallies showing how a foundry worked even if only with simple work. Look at the detail ! Using the method described, a homemade furnace and tools and working almost literally "in the field " I would say that the only way you would get better detail is using the Lost Wax Process.

Some may say otherwise but for me using brass, and the only part I bought was a dip pyrometer, though even that was adapted to suit ! It tells me the temperature which I say is vital for non ferrous metals, cost - about £80, money well spent !

For those who say they couldn't do I say try, it's not rocket science, the Greeks and Romans did it without half the knowledge you have on tap here ! Good Luck, Noel.

Edited By noel shelley on 03/07/2022 12:50:32

Steve, The Bromsgrove sand I got may have had bentonite in it as a natural ingredient, it just wasn't enough for me. I was given a bag of sand to try a couple of years ago by the engineer I made the name plate for. It needed sieving too, and I added some bentonite to it. My very fine sieve has holes at about half a mm. The ordinary sieve is about 1mm. I have coarser sieves when I need to speed things up.

If you find a supplier of ready to use greensand please let me know.

Noel, that is a great plaque! Did you 3D print the pattern?

Lee

I have heard Skegness sand, specifically from Gibraltar Point recommended - but you will break several hundred laws etc if you filled up a bucket or two!

Steve, What machines, if any do you have for machining or are you only set up for wood-spoiling instead of metal-spoiling?

If it's SDTS in Nuneaton that you are using, I'm in Rugby. If you want to try making a casting that's a tad larger in all dimensions, I could mill it to the desired final dimensions.

Hi Lee, Thanks .The back ground is a perspex disc covered with a double sided adhesive tape, the lettering is traditional white metal foundry letters , I have sizes from 1/8" up to 4" in several styles and the relief in the centre is a brass stamping. I'm not sure 3D printing was even common in 1995. Noel.

Hi Mark, yes I have machines, I’ve got a Zyto lathe, a Dore Westbury mill, and a Burke #4 horizontal mill. I spent a while trying to work out how to do this. The project is a set of hollow and round planes. That’s 16 hollows and 16 rounds - 32 planes, all with different dimensions = 32 sanding blocks. I was reducing this to 16 by putting 2 profiles on one block. I thought about turning and boring the blocks from round stock, but the amount of metal is significant and the waste would be substantial. I thought about milling from rectangular stock using the vertical mill and my little rotary table, but they are 4” long and get quite skinny, so it’s not practical.

the reality is I don’t actually need them in brass. Basically, I made a #14 round plane, which has a 2” radius. It was very difficult to get the sole flat enough by hand for the plane to perform properly. I had the idea of 3d printing a sanding block of the right dimensions, and it worked beautifully - flat sole to a couple of thou, very easily. Then I thought it would be nice to have a set of sanding blocks in brass to hone the planes in the future as and when needed. So all I need to do is 3d print the blocks, put them in a bucket of sand, melt some brass and pour it in and hey presto, sanding blocks. Turned out not to be so simple, but if I can learn a bit about casting, then I can do some other projects.

Thanks for the offer though.

Steve