Model Engine Maker

Supporting => Casting => Topic started by: gadabout on July 26, 2020, 08:47:47 AM

Title: Casting a V8 first ever attempt!
Post by: gadabout on July 26, 2020, 08:47:47 AM
First Casting, this is my first ever attempt at pattern making ,furnace building , core making and ramming a pattern then pouring, quite happy , a few flaws but I am going to give myself a pass mark!😁
cheers
Mark
Title: Re: Casting a V8 first ever attempt!
Post by: nj111 on July 26, 2020, 09:37:30 AM
Very good, I recall my own efforts went on for months until I got decent results!
Title: Re: Casting a V8 first ever attempt!
Post by: Vixen on July 26, 2020, 10:22:33 AM
Hello Mark,

Wow, that's a fantastic achievement. Well done. :ThumbsUp: :ThumbsUp: :ThumbsUp: :ThumbsUp: :ThumbsUp:

There is nothing in the world like the excitement and joy of knocking the mold box into the sand pit and finding the gleaming metal of your first successful casting sitting in the burnt sand and still too hot to handle.

So, we have the first ever flathead V8 Seal pup!!!!  Does your newborn engine have a name yet? That's sure going to be an interesting engine build to follow.

What metal did you use? Was it an ingot of 'new' metal or did you recycle a mountain of empty Fosters tinnies?

The core material looks untouched by the heat. What did you use for that?

Is that a centre bearing I can see?

Well done: Bravo Bravo

Mike
Title: Re: Casting a V8 first ever attempt!
Post by: scc on July 26, 2020, 10:57:01 AM
Great job :ThumbsUp: :ThumbsUp: :popcorn: :popcorn:    Well Done         Terry
Title: Re: Casting a V8 first ever attempt!
Post by: Zephyrin on July 26, 2020, 11:23:01 AM
I would have liked to get that for a first attempt! a flat head V8 with cored passages wow, congrats...a pretty good start !
Title: Re: Casting a V8 first ever attempt!
Post by: Jo on July 26, 2020, 11:59:43 AM
Well done Mark  :ThumbsUp:

There is no limits to what models engines you can do casting for now.

Jo

P.S. What Ali did you use? I have been told that Alloy car wheels are very good source of metal for home casting  ;)
Title: Re: Casting a V8 first ever attempt!
Post by: Mcgyver on July 26, 2020, 12:48:07 PM
nice work...that really expands the capabilities and possibilities
Title: Re: Casting a V8 first ever attempt!
Post by: gadabout on July 26, 2020, 08:00:32 PM
Thanks guys(and gal)!
Mike, was thinking maybe a Walrus! you know an oversize Seal! Yes centre bearing web hopefully. The cores were a baked sand recipe from Myfordboy's pages
Mike/Jo, the ali was some offcuts from years ago that came from  cast aluminium repro lace fence panels that I saved from a welding shop.
Will post some core and pattern pics when I can work out how to from my work computer.
cheers
Mark
Title: Re: Casting a V8 first ever attempt!
Post by: gadabout on July 26, 2020, 10:13:29 PM
These are some pics of the patterns and cores, there is one more core not shown. The patterns had 12 loose pieces that had to be withdrawn after moulding. I think I moulded about 15 times before I was happy enough to pour, even then they were really not good enough but I needed to pour before I lost interest in it all!! The cores are two piece, placed into each half of the moulding boxes. The core box is a built up arrangement from ali plate ,baked in an oven for 1.5 hours at 200 degrees in the core box, the core box is then disassembled to extract the core. I really do need better sand than my homemade stuff of silica sand and bentonite, really would like to try petrobond but have not been able to find any here in Tasmania, Australia
regards
Mark
Title: Re: Casting a V8 first ever attempt!
Post by: gadabout on July 28, 2020, 10:10:59 PM
I have done some machining on the casting and there are Zero signs of porosity! A few spots show signs of the ali starting to freeze near the end of the pour and for the next one I will change the sprue size I think as I reckon it was pouring a bit slow. Also I think I might have poured to cold not having any way to measure the temp just poured when it was molten.
cheers
Mark
Title: Re: Casting a V8 first ever attempt!
Post by: crueby on July 28, 2020, 11:50:30 PM
Looking great - how big are the castings?
Title: Re: Casting a V8 first ever attempt!
Post by: gadabout on July 29, 2020, 12:18:15 AM
Chris,
 they are 4.75" (120.5mm) long

Mark
Title: Re: Casting a V8 first ever attempt!
Post by: nj111 on July 29, 2020, 01:58:55 PM
Most of my casting problems were due to me overheating the aluminium or keeping it molten for too long, leading to absorption of hydrogen and producing a casting containing thousands of tiny bubbles which become visible once machining has commenced.  Hydrogen absorption increases rapidly above 740'C so I keep it within 760'C max.
I found a probe in the melt (that plugs into most multimeter thermocouple sockets) gave me a reliable indication of temperature and as a precaution I got hold of some degassing tablets (Ecogas 16)  from a foundry supplies firm and I plunge one of those deep into the melt shortly before pouring.  I'm sure if casting more regularly one would get to know exactly when to pour without needing a temperature probe, but I for sure need that information!
Title: Re: Casting a V8 first ever attempt!
Post by: Alyn Foundry on July 29, 2020, 04:37:50 PM
Hi Mark.

That's one heck of a casting for a first attempt, very well done.

My first was over 40 years ago and a failure too, it cold shut before fully filling the void.

I'd like to suggest that your " ingate " was a little small onto the casting so you could try making it a little bigger the next time. Aluminium doesn't have the same " weight " behind it so the quicker you can get it in the better.
Your " sprue " diameter looks fine but an additional " header " on top of the box can help increase the pressure in the moulds cavity.

A good " covering " flux will help with both gas problems along with more yield from the metal melted. Believe it or not we used " mothballs " as a degasser before turning to proprietary brands later. The speed at which you can " drop " the metal is also important, this reduces gas absorption to a minimum.

The largest casting in Aluminium that I did weighed 120Kg, took nearly 3 days to cool and ended up as a prototype press tool for MDF flooring. Fun times....

Cheers Graham.

Addendum.

Mark, I don't know where you're placed in the world but when I was in business we used the services of Foseco, Tamworth Staffordshire.  The flux in question was called    Coverall, Salmon pink in colour and amazing at keeping the gas levels low and the " dross " was just dust. We tried to avoid degassing due to the toxic nature of the fume. For Aluminium patterns a few pinholes wasn't much of an issue but we used their tablets for important castings.

Lol.... Tasmania..... Try reading the script properly G.

Oh.... Petrobond has a nasty habit of staining the surface of Aluminium you'd be better off trying to find some decent, fine grained moulding sand and either go the " Green sand " route or try Sodium Silicate mixed with your Silica sand and use CO2 to set it.
Title: Re: Casting a V8 first ever attempt!
Post by: Twizseven on July 29, 2020, 10:09:01 PM
Graham,

Good to hear you used Foseco at Tamworth.  My next door neighbour a fair few years ago used to be their Patents Director (he has since passed away).  He got me a summer job working in the research labs when I was 18.  It was great fun mixing up Exothermics to put on top of castings.  Used to make up mixtures, put them in a polybag and then dump them rapidly onto a furnace type of hotplate and then monitor the temperatures and see how they hardened and crusted up.

Colin.

PS hope to come and see you in near future to collect some castings.  Will give you a ring.
Title: Re: Casting a V8 first ever attempt!
Post by: Graemep on July 30, 2020, 12:53:52 AM
 Hi Mark

For foundry supply have a look at Green Sand Foundry in Victoria
There shop has most things you are looking for.


Graeme
Title: Re: Casting a V8 first ever attempt!
Post by: gadabout on July 30, 2020, 01:12:47 AM
Graeme,
 Thanks I have looked there. Maybe I am expecting too much from my sand mixing , I don't know what is normal in dryness/wetness grain size etc, I see youvids of "sand" that looks so much better than mine!
cheers
Mark
Title: Re: Casting a V8 first ever attempt!
Post by: gadabout on July 30, 2020, 01:24:59 AM
Graham,
 I have thought about going the sodium silicate route, I have all the requirements to do it, silly question time .... would you remove the patterns before or after gassing?
I wish I could get some fine grained moulding sand here, all I can get is from the landscape suppliers and I sieve that through a kitchen sieve, you are not supposed/allowed to get it from the beach here!
All advise  and help greatly appreciated with my casting attempts
Mark
Title: Re: Casting a V8 first ever attempt!
Post by: Mcgyver on July 30, 2020, 01:46:39 AM
Quote
Maybe I am expecting too much from my sand mixing , I don't know what is normal in dryness/wetness grain size etc,

A customer of mine is a commercial AL foundry and in response a question about proper mixes for green sand on another forum I asked him.  He says the mix of sand, bentonite and water will vary depending on the size of the casting but suggestions 5-10% bentonite and 3-5% water by volume for smaller back yard castings, all by volume.  The amount of moisture goes up as the size increases.  You can also get bags of premix that make easier. 

Not from him, but I've heard clumping cat litter is just bentonite....makes it easier to source.  You can reuse the sand, add a bit of fresh bentonite as some gets burned.  In commercial ops they constantly scrap a percentage of sand and add new, but they have mullers, shakeout tables, screens and coolers to make processing easy
Title: Re: Casting a V8 first ever attempt!
Post by: gadabout on July 30, 2020, 03:38:09 AM
I am using finely sieved sand and 12.5% bentonite by weight plus water , its just knowing how much water is enough and not too much, I don't want a little explosion happening! I think with my pour the sand was too dry and a bit crumbly and had some minor drop out happen.
cheers
Mark
Title: Re: Casting a V8 first ever attempt!
Post by: Roger B on July 30, 2020, 07:30:36 AM
 8)  8)  :praise2:  :praise2:
Title: Re: Casting a V8 first ever attempt!
Post by: Alyn Foundry on July 30, 2020, 12:08:08 PM
Good morning Mark.

Yes, you'd leave your " well dusted " patterns in the box whilst you gassed. This ensures a " crisp " finish and no likelihood of the sand moving during the set.

Now, the sand used for " Greensand " moulding ain't just any old sand, it's quarried. Beach sand has seen eons of erosion and all those little grains are quite smooth. One of the reasons moulding sand binds is because of their irregular shape and the sharp edges help to interlock the grains. Bentonite can, and is added to increase the bond strength but, with the right sand it isn't always necessary.

" Tempering " is the term used for the addition of water to the sand. Obviously too wet and steam is generated which can cause disastrous results. Too dry and the bond is weak. On the shelf I have a lovely piece of kit for determining the moisture content precisely but I haven't used it in years. Why? Because I was taught the " squeeze test " very simple and effective. With a dry hand pick up a handful of sand, close the hand firmly then open. The compressed sand should have a reasonable bond if squeezed between finger and thumb but, more importantly you shouldn't see too much of the sand adhering to your palm. A good indication of too much water will be lots of sand grains stuck to you.

Back in the days of Rhuddlan and Buckley ( commercial Iron founders ) they used a mix of sand Bentonite and fine Coaldust. This was called " virgin sand " this mix was only used for " facing " the pattern. It was pushed gently through a riddle to liberally cover the pattern then shovels of the used, re tempered sand
" backed out " the moulding box. Then the process of " ramming up " began. This was quite something to see, the guys would, depending on the size actually stand on the mould whilst ramming up with differently shaped Iron tools. Once firm a final " strickle " flatting off of the box was done before being hit by the venting tool. ( sharp pointed wire on a handle ) multiple small holes were placed being carful not to touch the pattern then the whole box and board were deftly turned over and placed on a bed of flat, lightly raked sand. The top box saw the same process but with the addition of " sprue " and risers where necessary.

Although I don't do much here in the " Backyard Foundry " these days my sand is still near perfect after over 30 years of use. What I'm saying is that if you were to buy a reasonable amount of " proper " Greensand moulding sand it would be a good investment.

Cheers Graham.
Title: Re: Casting a V8 first ever attempt!
Post by: awake on July 30, 2020, 06:13:58 PM
I have thought about going the sodium silicate route, I have all the requirements to do it ...

I am wanting to get into casting ... just don't have the time to add that on at this point. But I have watched lots of YouTube videos, so that makes me an expert, right??

There is a caster called "luckygen" on YouTube, mostly works in cast iron but sometimes aluminum or bronze. I was quite startled to see him using resin + hardener (as would be used for car-body repair, I think) to harden his cores. He mixes in just a tiny amount, and mixes it thoroughly. I've never seen him discuss the merits of this approach vs. sodium silicate, but I have often wondered ...
Title: Re: Casting a V8 first ever attempt!
Post by: tghs on July 30, 2020, 06:56:54 PM
I have cast some things and had some things cast for me and done my own lost wax work over the years,, my work on old navy models led me to this one late night,, the 1890's pump that modern folks have a hard time reproducing due to the complex coring of the casting.    http://www.rockisland.com/~marshall/whatsnew.html many of the items we think about casting fall between foundry casting and jewelry casting,, have you looked into delft clay as a casting media, jewelers use it for larger items..
Title: Re: Casting a V8 first ever attempt!
Post by: ddmckee54 on July 30, 2020, 10:28:05 PM
Mark:

That block looks pretty good to me.  I always  wanted to see a flathead model with Ardun style heads. (Hint, hint, hint!)

Keep up the good work, because it's all uphill from here.

Don
Title: Re: Casting a V8 first ever attempt!
Post by: gadabout on July 30, 2020, 10:35:12 PM
Don,
 I have no idea what Ardun heads are I will have to google that!
The casting is I think useable and will be my trial machining block, I do need to do some alterations I think to one of the core molds  and I want to get better sand to get a finer finish. Also I think I poured too cold so a pyrometer would be good!

thanks
Mark
Title: Re: Casting a V8 first ever attempt!
Post by: ddmckee54 on August 03, 2020, 09:04:00 PM
Adrun heads were originally designed as a valve-in-head replacement head for the Ford flathead engine when used in a truck application.  If I remember the story correctly, they were originally designed for use on garbage trucks.  The exhaust ports which were originally routed through the cooling jacket in the block caused over-heating when the engine was under load. 

As a replacement head for a truck engine the Ardun head wasn't very successful, they were kind of expensive for one thing.  BUT, they were the holy grail for the Ford Flathead hot-rodders of the time.  Many speed records were set with Ardun equipped Ford flatheads.

Don
Title: Re: Casting a V8 first ever attempt!
Post by: gadabout on August 04, 2020, 06:51:12 AM
Don, interesting but I think I have already bitten off more than I  can chew at the moment ! Don't think I will be making any Ardun style heads , sorry
Mark
Title: Re: Casting a V8 first ever attempt!
Post by: ddmckee54 on August 07, 2020, 08:54:10 PM
I know what you mean.  It's WAY down on my bucket list too, and I'm the one that wants to see it done.  Too many other things to do and skills that I need to learn before it's even remotely possible.  I just keep hoping that I can at least experience it vicariously through somebody else's buiid.

Off and on for a couple of years, a lot more OFF than on, I've been working on the drawings for a 1/8 scale Ford flathead with Ardun heads in 2D CAD.  I may have to dust those files off, poke at them a little more, and start getting them in 3D CAD.

If nothing else it keeps me off the streets and out of trouble.

Don
Title: Re: Casting a V8 first ever attempt!
Post by: Vixen on August 07, 2020, 09:57:37 PM
Hello Mark,

I was thinking about a centre bearing on your V8 Walrus. It may be possible to fit a larger diameter, thin section bearing in the centre without weakening the already whippy crankshaft. The standard Seal crankshaft has an outside diameter of 1.125 " (28.6mm). It would be possible to fit a larger diameter thin section deep groove bearing in the centre, but you would probably have to play around with the casing patterns.

The SKF 61806 (or equivalent) is 30 x 42 x 7, a big enough bore to fit over the 1.125" (28.6mm) shaft.

However, the SKF 61805 (or equivalent) is smaller 25 x 37 x 7 and could be threaded over the other throws to get to the centre position. You would need to design in a short 25mm disc between number 2 and number 3 crank throws. It should be possible with some careful thought.

Stay safe

Mike
Title: Re: Casting a V8 first ever attempt!
Post by: gadabout on August 07, 2020, 10:57:05 PM
Mike,
 Thanks , that's an idea that I hadn't thought of, would need to check if it would clear the camshaft.
Not yesterday I line bored the block for the 1.125" bores and the .625" centre bearing mains, it's very similar to he Sealion setup but fractionally smaller. I kind of figured if it worked on the Sealion it would work here , very hard (impossible) to see what's happening when boring the centre main, I did the line boring on the lathe mounting the block on its sump face to a subplate on the cross slide, it was cut measure adjust etc etc
Regards
Mark