Casting the SR20 throttle body, Part 2, Metal preparation, pouring , and breakout 

shem, You just have to have a sand fine enough (and know how to work with it 😏) The finish on these castings was very good, its a job that always seems to finish well but I have seen others do better and I have done better myself on other work in other alloys... Martin

kcraig, Go for it! But do be prepared for a fairly extensive and steep learning curve. Also there is a bit of equipment to be gathered some of which will cost a few dollars. Making it look easy is just a matter of practice... Martin

Chirpy, Once again thanks for letting me know of the problem. It was of my making, when I saved the file out of wlmm it did not save properly and I up loaded a corrupt file. Resaving and re uploading was the solution. Yes I was happy with those castings, not quite the best I have done but very, very close to it. Martin

no problem, us youtube creators have to watch out for each other. I just hope that someday my castings can someday come out as nice as yours.

Chirpy, All it takes is a totally bloody minded pedantic attitude to intend to produce the best looking casting you can, both on the surface and inside the metal too. Oh, and a lot of practice, I started about 60 years ago. Just keep at it and always be open to new improved ways. Martin

Solarguy, No effect at all as once the mould is full and the metal in the sprue stops moving it will solidify very quickly, the basin may stay liquid for a little more time but it is cut off from the casting by the solid sprue and thus cannot feed through to the casting... Martin

Joseph, Thank you. This particular casting did seem to finish a little better than many others that I cast... Martin

Jesse, That's what I like to hear, thank you… Martin

Clem, Thank you for your comment. My aim in making these videos is to pass on at least some of what I have learned by practice and study over the years. If someone like yourself gains something from them then I am well pleased.... Martin

William, Thank you. To be honest of all the various throttle bodied that I make this particular one finishes the best. The others are close but this one just seems a little better that al the others. I think its because it is a little thinner and therefore solidifies quicker meaning there is a little less time for the metal to fully penetrate the sand surface. But in other materials (an aluminium silicon bronze) I have achieved a finish quite a lot better than this. I have to admit though that I am not unhappy with the finish - and nor is my customer...Martin

Dave, In truth for reasons that I an not completely certain about some castings juts produce a better finish that others. Of the 6 or so throttle bodies that I make this one produces the best finish. My suspicion is that as this one has the thinnest wall section of them all this somehow helps. Sharing is my pleasure and thank you for your comment... Martin

Occif, Yep, you have to put in the ground work to get the required result - I guess everything in life is like that....Martin

Leddie, Thank you for saying so - good luck with your projects. Have you looked at EFI Hardware's range they may have what you want - not an easy thing to make for yourself... Martin

@@olfoundryman8418 it's ok i'm a toolmaker and have the necessary equipment.i just haven't done any casting. i have already made a split pattern and am part way through making the furnace. something i'd like to do and would help me with my projects instead of searching for appropriate parts which i usually have to adapt. i've watched several more of your videos today and may have some questions at a later date if that's ok. cheers... pete.

Andrzej. Thank you for the comment, I very much appreciate it. I must send Vegoilguy a thank you!... martin

Nigel, You can have as many comments as you like. Yes that skin is just like that on a sausage. It may wave about a bit during the pour but it doesn't flow unless one does something silly like disturbing it by overly turbulent pouring in which case it will end up in your casting as a nasty defect... Martin PS don't suggest that pay rise to the help!

Flying, On is never off one's rocker when thinking outside the box, its necessary to advance but on this occasion - well - maybe. The resin coated sand only sort of survives the casting process. I get about 4 to 8 uses out of each feeder extension - the slits cut in the top are a counter of how many uses each has had. With each use the resin bond in the sand against the metal is destroyed and the surface falls away. The inside diameter gets bigger with every use and while this does not matter with a simple feeder extension like we are dealing with here it would be catastrophic with an actual casting. The first casting would be Ok the second reminiscent of the first but each succeeding one less and less reminiscent! The process of clam shells moulds made with resin coated sand is quite common, but each mould is only used once, and it does require heated metal pattern plates to make the shells... Martin

@@olfoundryman8418 Thank you for the thorough responses Martin. I feel your videos have given me enough knowledge about the process to inquire about getting some prototypes cast at a local foundry.

eric, I am glad that my information has helped. If I am correct Nitral 10 is a tablet that decomposes to give off nitrogen gas when plunged into molten aluminium and that - in theory - this should degas the aluminium. Many years ago I used an earlier version of such tablets when I could no longer get hexachlorethane. I did not like them! They bubbled so violently that they threw 50 mm of metal out of the crucible and all over the inside of my furnace - I had to put a steel splash ring on top of the crucible to contain the metal. Such violent bubbling and splashing only serves to expose more metal to the atmosphere where it will react with water (humidity) to generate more hydrogen thus it can result in an increase in hydrogen rather than a decrease. Also the generation of nitrogen was over way too quickly, degassing takes time 5 to 10 minutes at least with a process like this and the tablets used to produce nitrogen did so for only about 2 minutes - I used to break the tablet into two bits and use one at a time to give me 4 minutes of degassing time but its still not really enough and I did not feel that I was getting good results so I went over to argon degassing with a small bubble lance - nowhere near as good as rotary impellor degassing but best I can do. Now perhaps the tablets you have are a new and better version but if they only gas for a short time and particularly if they bubble so violently that they splash metal out of the crucible I would not bother using them. From memory (old and untrustworthy ) I used 1/2 a 50 Gm tablet in an A25 crucible (10 Kg of aluminium) My advice on degassing for the hobbyist is don't bother. Just use the best metal you can get, make sure its clean and dry, melt it quickly, don't get it too hot and pour without delay unless your work is very thick any gas bubbles will be very small (less that 0.5 mm diameter) anything bigger is almost certainly shrinkage if feed was bad or trapped air because of bad gating. I think many get a bit OCD about gas and ignore much more serious issues.... Martin

@@olfoundryman8418 Wow thanks for this detailed answer ! i try nirtal 10 with a lower addition to see whats happen. What do you mean with "best material" i usw often use alumonium car rims with no coating and i dont mix other aluminium in it. Which temperatur do you recomend for pouring ? thanks a lot !

Graham, I like to think that the finish was better than shell mould! 😊I do in fact use shell moulded cores for this job and the finish they give inside is not a patch on the finish outside. I would have poured within 10 degrees of that 740 deg. C. This particular throttle body was the thinnest section one that I did - others (thicker) were poured as low as 710 deg C.... Martin

@@olfoundryman8418 Thanks for that Martin, [that's me told then!! hehe] I usually pour my plaques around 70c mark they're pretty even . thanks for the info.

Graham, I have to admit to being a bit paranoid when it comes to pouring temps. I have a bad tendency to pour too hot. I hate the idea of spending a morning making moulds only to have them all fail because I poured to cold and none of the castings ran! Its simple I guess - pour too cold and you get nothing, too hot and at least you get castings maybe not quite as good as they could be but hopefully useable.... Martin

@@olfoundryman8418 Hi Martin, there's nothing worse than prepairing a mould melting then pouring [& thinking " that didn't seem to use much metal"] only to find out why on shakeout, all that work for nothing [we've all done it!!]Graham.

Head Yep, been there done that and Oh, how I hate it - as you say, all that work for nothing and its why shakeout is always a nerve wracking time! 😱.. Martin

The powder sprinkled on the risers just after pouring is an exothermic compound designed to keep the risers liquid for longer so they can better feed the casting. It is a commercial product called "Ferrux NF" and is made by "Foseco", Martin

Marty, The material spooned on just after pouring is an exothermic compound (similar I guess in action at least but not composition to thermite). Its job is to keep the feeders hot for longer so they can better provide feed metal to the casting. This product is made by "Foseco" and is called "Ferrux NF" The most able helper was the good lady wife, she does not like being visible in the videos! Martin

I figured it was your better half cracking the whip to make sure the job gets done! I thank her for being the camera person. Job well done!

Baum, Aluminium does indeed attack steel and most if not all other metals too! It absolutely loves to devour stainless steel for example. Once the aluminium “wets” the steel attack is rapid - the steel is destroyed and the aluminium contaminated. The ladle I use is mild steel but is protected from attack by a coating. This coating is called “BN Hardcoat” It is made by ZYP coatings in the USA. This a boron nitride based material that repels molten metals up to about 850 deg C. I apply a fresh thin layer of this coating - its water based and you just paint it on - every day before casting. I heat the coated ladle to dull red heat to dry thoroughly before use. It works very well but it is very expensive being about $200.00 for the small American gallon. I think its possible to buy smaller quantities. I also use to to coat my thermocouples and degassing lances.... Martin

@@olfoundryman8418 thanks Martin for the detailed explanation!

jimivx, I use commercial grade argon for the degassing... Martin

Hi I have made a mistake here l think the powder went on top of the riser sorry about that .

Lance, The powder is indeed on the top of the feeders. It is an exothermic compound (A bit like thermite). Its job is to catch fire and generate a lot of heat, this keeps the feeder liquid for longer so it is better able to provide feed to the solidifying casting below... Matrtin

Harrison, Unfortunately I had no idea what a "Vince Lombardi trophy" looks like although with the aid of the great God Google I have found out - it seems to be a football (US style) on a truncated 3 sided pyramid. If I was asked to make something like this I would seriously think about making it in two pieces. The football as one and the pyramid as the other. Both parts would have to be made as fairly thin walled hollows as if made solid shrinkage would be a problem. In two pieces the making and supporting of the cores necessary to make each part hollow is much easier. The triangle becomes on its own quite a simple casting job with the to be engraved face as parallel to and most likely coincident with the mould parting line. The football though is another matter as there does not seem to be a suitable parting line for it to be made in a two part mould as the re-entertant nature of the four seams causes problems. In fact even casting it in a, say, four part mould would be difficult. The easiest way may simply be to cast it in a two part mould with only two of the seams (the one with the lacing and that opposite it) and cut the other two in later. The parting line would of course be where the two seams are later cut. Hardly an elegant solution I admit but with the limits of green sand moulding it is difficult to see a better way. One alternative would be to have it made via investment casting just as a statue (bust) would be made - probably a bit expensive though! Sorry to not be more helpful. Good luck, Martin

Olfoundryman thank you so much for taking the time to reply to me. I will use the information you gave me and I might end up making a RU-vid video of me making the trophy so I will let you know!

Harrison, What ever you do make a video of it. Even if you feel that it has not turned out good enough to up load it will provide you with a valuable reference to look at and develop improvements in your methods.Good luck with your efforts and I look forward to seeing the video. Martin

Agustin, No, I don't recycle the shell sand. I don't have a lot of it for a start and its quite cheap anyway. I imagine that foundries who use a lot of it might well recycle though... Martin

MJ, The powder (it's actually a dull dirty brownish red) I put on the top of the feeders is called "Ferrux NF" it is made by "Foseco". It is an exothermic and its job is to catch fire and generate a lot of heat. This keeps the feeder liquid for longer so it is better able to feed the solidifying casting underneath..... Martin

@@olfoundryman8418 Thank you Martin. So its basically thermite powder. Interesting.

Mj, Yes, indeed it is a type of thermite - slowed down a bit and with some strange additives that sort of expand to make the ash more insulating. ...Martin

Mohammed, I assume that you mean the powder I add at 6.12 for example. It is an exothermic compound called "Ferrux NF", it is made by Foseco. It is added to keep the feeders liquid for longer so that they can provide better feed the casting.... Martin

Thank you for your reply Sorry, I mean adding the powder at the time of 4:58 ز

Mohammed, At 4.58 I am actually removing dross not adding anything but perhaps you mean at 3.58. At this time I am adding a drossing off flux, it is "Coveral 11" made by Foseco. I very lightly stir it into the surface of the metal without any splashing. It partially melts allowing it to react with any oxides floating on or just under the surface of the metal, frees them from the metal with the aid of the exothermic reaction that you can see occur starting around 4.17 thus allowing the removal of these oxides as a dry (free of metal) material at 4.58 once the exothermic reaction has died down, this takes a minute or two and I edited that bit out of the video...Martin

Thanks my friend

William, Yes, it is the core blowing out when the steam from the water gets in behind it. Oddly perhaps its only the first 4 to 6 that do this when they hit the cold water, by number 7 the water had warmed up and no pop. I like the pop it gets the core out for me!😊..Martin

Jerry, Yes, It keeps the feeders liquid for longer so they are better able to provide liquid metal to the solidifying (and thus shrinking) casting underneath... Martin

rizendell, The flux I use is "Coverall 11" it is made by "Foseco". The spoonful on the top of the feeders is an exothermic compound, its job is to catch fire and generate a lot of heat. This keeps the feeders liquid for longer so they are better able to provide liquid feed metal to the solidifying casting underneath. It is called "Ferrux NF" and it is made by Foseco...Martin

Joel, Yes it is indeed LM25 or as we call it out here 601 (356 in the US) It is perhaps the easiest aluminium alloy to cast and it heat treats well. I buy it as ingot from a reputable supplier.. Martin

@@olfoundryman8418 Agreed my next favorite alloy is DT5008 as it naturally age hardens.and between these two are a good working set of alloys. Then add in LM6 and your made. Perhaps Martin you use are using StBrTi master rods for your finial modifying and grain refinement treatment?...Joel

Joel, Locally we have an alloy called A1E it is very similar to DT5008, For many years I used it to first sand cast and later gravity die cast support blocks for hardened shafting -must have made thousands of them in a range of metric and inch sizes until the Chinese cut us to pieces on price. As you say the alloy age hardens naturally over about a week and then is a delight to machine and it has a most pleasant white colour very similar to Magnesium alloys. In theory it can be anodised and coloured too. I do use LM6 (401 locally) but only for some gravity die work, it is a bit problematic in sand (not impossible just have to know how to handle it). I do not use an strontium additions as they can cause gas problems and more importantly for me metal mould reaction with my green sand. I do however use 5/1 Tibor master alloy - 5% Ti 1%B bal Al - as a grain refiner (it also helps settle larger oxide particles) but usually I only do this for sand casting not for gravity die work..... Martin

@@olfoundryman8418Martin, as you more than likely know, LM6 is a eutectic alloy and has a lot of centreline shrinkage and is hard on the feeders and hot spots. DT5008 has an beautiful gold planta to it when anodised due to the chrome content 80%TI master tablets are ideal for this alloy aiming: for 0.22%-0.25%residual titanium is fantastic for reducing the grain size and improving feeding characteristics. I would not advocate for the other LMxxx or 601based alloys, however. I have heard somewhat about hydrogen pick up with Strontium from what I gather its an active oxide affecting element hence its effect on the so-called steam reactions. using hard chemical sand seems to be fine, but agree a 4" inscribed sphere is a practical upper limit before needing more precautions... Ahh...for the time we make perfect castings each and every time...Joel

Joel, Yes, I am familiar with the solidification behaviour of LM6 (I am a metallurgist) Because of its single temperature solidification it behaves like a pure metal - high fluidity but centreline shrinkage that appears to be more than other alloys (but it isn't). Hot spot sensitivity is indeed quite a problem and feeders need to be placed sized and shaped with care. Gate casting junctions are a frequent trouble spot best avoided by gating through the feeder. In addition I have had problems when castings in LM6 decide to solidify with a marked coarse eutectic cell pattern - you can get a lot of porosity around each cell. Modification is the cure but as mentioned Strontium gives me problems so if I have to do it I will use Na. (I have vac packed Na ex Foseco.) H pick up with Sr is a bit of a moot point but under some circumstances it does occur. In my case I believe the Sr changes the oxide film on the aluminium and renders it much less protective and more permeable to moisture from the sand. Be apparently has the reverse effect but what fool will use Be. Sr modified castings come out of my sand a dull grey sort of "burnt" appearance much like the surface of a casting that has been through a T6 process but worse, subsurface gas is usually present. It is no doubt a "steam reaction". I would imagine that hard sand would not cause the problem and shell core does not seem to either but silicate cores do to some extent. I used to use grain refining tablets (again ex Foseco) but find the 5/1 Tibor much easier to use, in addition the Tibor helps precipitate oxide films out of the metal because boride particles apparently attach to the oxide films and being heavy sink them to the bottom of the melt. Perfect castings, now there is a dream - but Bob Puhakka has achieved it using John Campbells methods plus a few mods of his own, In the mean time the rest of us do the best we can - well, some of us do, but most do not bother and from my observation seem intent on doing everything possible to make as bad a casting as possible - damn great high oversized parallel sprues and "degassing" with water producing chemicals (washing soda!)😱 .Grr ..🤬.… Martin

Coffieman, The spoonful on the top of the feeders is an exothermic compound, its job is to catch fire and generate a lot of heat. This keeps the feeders liquid for longer so they are better able to provide liquid feed metal to the solidifying casting underneath. It is called "Ferrux NF" and it is made by Foseco… Martin

Can, The pouring temperature I use varies from about 690 deg. C to about 760 deg. c but this casting was poured at 720 deg. C … Martin

Hello Mr Martin, I am doing Machine and I want to learn more about casting aluminum. I am just an beginner in casting, have no experience. Plz help me with a few stupid questions. The first question is plz show me how to handle best sand when casting, what is maint components in sand ? Here is my email address canmohp94@gmail.com plz message with me via email, many thanks 🙏🙏🙏

Can, The main components in a foundry sand are the sand itself preferably a quite fine sand ,clay to bind it together usually bentonite clay ,and water to make the clay sticky...Martin

Thomas, Come back to me in a private message with an email address that I can send details of my address to. I would very much like to see the pictures of your work, Martin

Amtpdb1, Its not a stupid question. The powder that I put on top of the feeders immediately after I have poured is an exothermic called "Ferrux NF" it is made by "Foseco". It catches fire and generates a lot of heat. This keeps the metal in the feeders liquid for longer so they are better able to provide liquid feed metal to the solidifying casting underneath... Martin

Olfoundryman Thanks for the information and the informative videos. I would like to try this sometime. I remember sending out the molds for superchargers and having the aluminum parts come back to the shop for machining. The whole process is fastenating.

Mark, Currently I make the ratio about 325 to 300. But yes I think that I should have put the word casting in part one as well as in part 2, a regrettable oversight on my part. Martin

TKO, I understand that the people who put them on their cars find them pretty "beefy" too...Martin

agreed, so i guess the linkage still fits and the like...having a thick wall should help remove heat..these castings are nice..i worked in a foundry in 75 casting brass ndz bronze iron...mold maker on the tabors.

TKO, I think that people buy them as a package which includes al the fuel rails new linkages injectors electronics etc. If you go to the EFI hardware web site listed as above you can see the finished articles and what comes with them... Martin