Sand cast aluminium Brake fluid Reservoir
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- Опубліковано 11 жов 2024
- Sand casting a brake fluid reservoir using a small threaded shell core.
This part was developed to solve the problem of refilling the fluid reservoir on an "under the floor " brake master cylinder. The part mounts under the bonnet on the fire wall and a pipe connects it to the top of the original master cylinder reservoir.
Excellent stuff - and great respect to you for pointing out your mistakes and how you made them - that way we all learn. Please keep these coming!
Andy, Yep, mistakes are the greatest and surest teacher, if at times a bit expensive. We all make them and as a wise man once said "the man who has not made a mistake has not made anything" I hope to do more videos soon... Martin
Thank you for another great video. I always learn something from you, they way you leave the "skin" undisturbed as you pour, not sliding the mold on the bench, etc.
Michael, If you are careful it is amazing just how the metal runs through its skin without the skin itself actually moving in with the metal, it may wave around a bit but basically it stays where it is. It is very important not to disturb that skin! If you do it winds up getting sucked into the metal, Its bit like throwing lots of plastic bags into a concrete mix, not very good concrete! Skins (or bifilms as they are called) in aluminium equals not very good aluminium. Also the skins are known to become the origin of shrinkage, gas porosity, and cracks under stress. Thus the need for good gating and the quietest calmest pour possible. Not sliding on the bench, I really should know better! In fact if you look closely at most of my videos when I move a box on the bench you will see that I have picked up one side of it at least enough so that only the edge of the box is actually in contact with the bench that way the feeder edge does not get damaged but I got carried away here, it is amazing how these little "errors" only seem to happen when one is videoing, well that's my story and I am sticking to it -:)... Martin
Love the pattern-drop technique. Much better than trying to pull the pattern free. Excellent!
Geoff, Yes, this technique works well for me. Other moulders with way steadier hands than me prefer the lift the pattern out technique. In fact I remember one lot of absolute legendary moulders who would put the pattern back after cutting all the gates and lift it out again just to make sure the cavity was right. This improved the finish and accuracy but I have enough trouble getting it out once let alone twice! Sadly these legends have now retired and without passing their considerable knowledge on, a great loss!..... Martin
I came because of a recommendation from vegoil guy. I subscribed because it is amazing to watch you work
Gearbox parts, trottle bodies, brake system parts... Hands of gold! It looks like you can make an entire car in your garage! Can i hope once to see casting of engine block?
Ashkira, "Hands of gold" what a lovely thought , thank you. Sadly I am not to good at sheet metal work (can't cast it thin enough :-) ) so a whole car is a bit beyond me and then there are those really difficult things like crown wheels and pinions :-)
As for an engine block, not much hope I am afraid as it would have to be small for I have no way of lifting big heavy moulds. Mould weight and therefore size is my big limit... Martin
Well, talking about engine - i never meant monstrous US style v8 :) But - never mind, i was a bit joking :)
Books on casting (those i could reach) say the best way to build water cooling jacket is by using prebaked cores with linseed oil - because of their high strength and gas permiability. People say that's outdated technique, so no one can show how it works (at least i was unable to find video on that). How do you think - does this "old magic" have any advantages over simplier technics (like liquid glass sand and resin coated one)?
Also, i've encountered a couple of mentions that caoline can be used in place of bentonite. Is it true, how you think?
Ashkira, Linseed oil bonded cores were perhaps the mainstay of the foundry industry for generations, millions of good castings were made with them. The mixes used often contained, as well as the linseed oil, things like flour (corn flour), dextrin, kerosene, clay, and water. The core once rammed up was cooked at around 180 to 200 deg C to cure it. These core were not very strong and gave out a lot of gas thus they often required wire reinforcement and careful venting. I tried such core making methods and found it an acquired art and one that is difficult to acquire!. Compared to modern core making methods I doubt there is much "magic". These days there are so many core making methods available that one is spoilt for choice. Cores are strong hard tough and give out little gas. Some interesting core work is on Mullernicks channel some of his other techniques are a bit sus but his core work is worth seeing. I have seen cores made by a gas cured urethane process that were so thin that you see through them they were for cylinder heads. Silicate CO2 is a bit old hat now too and has its problems but newer versions of the process are much improved. So I would consider linseed oil core somewhat "old hat".
Re clay - my sand is a Natural sand meaning that it is straight out of the ground and contains sufficient clay to make a good foundry sand. The clay is just some sort of natural clay possibly not unlike a pottery clay and perhaps something like kaolin. So, yes I think that kaolin would do as a binder for green sand work but I don't think that it would have any special advantages over bentonite. The latter is the popular choice suggesting perhaps that it is the better binder and considering that neither are all that expensive and both are readily available I would favour the use of bentonite... Martin
PS, Closest that I have been to casting an engine block is making pistons for one!
Thanks a lot for a detailed answer! I got the impression that my books are quite outdated.
Ashkira, If you are looking for a book that is not outdated, try John Campbell's "Castings Practice - The ten rules of castings".
Its quite technical so be prepared for a solid read. But if you follow its methods as far as able you will produce castings way better that the average.... Martin
Martin. Awesome video. I really liked how you spent more time explaining what you were doing and the end bit was a great way to summarise and wrap up the video. Bet that took loads of time to produce.
Mike, It took a little time but I am getting quicker as I get more used to my new video editing program. I never know how much to leave in or edit out. This one started at over 50 minutes, way too long, but I had to cut out a lot of info to get it down to something more reasonable. Still that gives me something to put in the next video!... Martin
Learn something ever time I watch your videos -- thank you!
Htral, Thank you for watching. It is my aim to pass on some of the knowledge that I have gained over the years. I find it very satisfying that people learn something from my videos... Martin
Very interesting in all aspects to watch as well as learn from! Love your work and attention to detail. I hope to have a go at doing some casting of my own in the future and thus far you and luckygen provide the best teaching methods and situational awareness I have seen. Slowly working my way through your library of video's.
Cheers from John, Australia.
John, No more procrastination mate, get out there and start casting. I know Lucky quite, well he lives not too far from me and we have shared many a cuppa and lots of good conversation. When it comes to casting Iron he is the best teacher out there, he has been at it for over 30 years.... Martin
@@olfoundryman8418 it will probably be in the new Year when I have my large shed ready to build a Foundry and also make some Flasks.
I did with my Father do some crude casting of Aluminium in the hollow of a brick with a hole drilled through the side to act as a feature that was needed in the part I wanted to make, it worked well. NO saving the of the mold, Ally cold and Hammer. lol Good days with Dad. Car diff worked well, did not know about degassing so our substitute was to use Oxy welding flux to reduce oxidization on the melt and done with a hand held torch made by Sievert, (BIG). A little older now and more wise as a result of your teaching as well as Lucky. I will video my first foray in to this Brave Old World of casting, stay tuned. lol.
Cheers from John.
joan, I await developments from your quarter with interest, good luck with it all...Martin
You used facing sand pushed through the riddle screen, then backing sand pushed through a similar screen. Does the facing sand have a smaller grain size? Is the facing sand also a "petrobond" type oil-sand mixture? I'm trying to improve the surface finish of my Alum castings. Really enjoy all your videos as I learn so much.
Matthew, The facing sand is the same sand as the backup BUT the facing has gone through a grinding procedure so it does have a finer grain size. I do not use petrobond at all. The two sieves I use (riddles are above 3/16 inch sieves below that or so I am told)are exactly the same size (1/16 inch) using a sieve breaks up any lumps and fluffs up the sand a bit this makes it ram a bit better a bit more evenly. The back up sand tends to build up in extraneous rubbish and the sieving of it removes at least the bigger of these lumps - if not removed and if they wind up on the cavity surface they can cause strange surface defects on the casting. Glad that you enjoy the videos... Martin
Always enjoy watching you work . I'd love to see how you made your flasks.
Chris, A video of at least the casting part of the flasks is one the "to do" list. I also plan a video on my journey through various design and types of moulding boxes, it will hopefully include my thoughts on a versatile but solid box design that can be made by just about any fairly serious hobby caster. Trouble is, that "to do" list is long and getting longer. I will work on it.... Martin
Olfoundryman and think some you tubers run out of ideas . At least you don't have that problem.
Chris, Not yet!
me to never run out of things to do if your passionate about it lol
Chris, I figure that if I run out of ideas someone will nail the lid on the box!... Martin
It is nice to see what the final part will look like once complete. Could you do that for other castings as well?
Jason, It is nice to see what the final part looks like and I do that whenever I can but unfortunately I usually do not machine the castings, the customer looks after that. So I rarely see the finished article myself. In this case I asked the customer, also a close friend, to bring a previously completed part when he came to pick up this batch so I could take the necessary photographs. I do ask customers to send me photos when the parts are completed but quite often this happens months later so sadly they never make it into the video. If you want to see completed versions of some of the throttle bodies that I make Google "EFI hardware" their web site has lots of photos... Martin
Is the shell sand available in small quantities commercially for the home foundryman? Product name and supplier would be excellent if you have time.
Matthew, I buy the shell sand in 25 Kg bags. I usually get about 15 bags at time but I should imagine that if you went to their door with cash you could buy just the one bag. I buy mine from a company called Macbro but that's in Melbourne Australia - you appear to be in Ca USA. just look up resin coated sand in your local phone book or on Google and give anyone you can find a ring. If they will not sell you just the one bag ask if they can suggest one of their customers who might be prepared to on sell a bag. From memory its less than $10.00 per bag... Martin
Loving the audio on these videos, great job ob the casting as always!
Law, I recently started using a wireless remote microphone set up, it is a Removu M1+A1. It was on special at half price for $50.00 (Australian) so it was cheap but I am well pleased with it as it seems to help tone down background noise and give my voice a better chance. I certainly feel that it has improved my audio.. Martin
I just love the background environment of your birds, wouldn't have it any other way. I really like your methods of work, keep going, good luck and happy holidays! :-)
Icinesis, Thank you for your kind words - I will try to keep at it... Martin
Once again another great instructional video Martin. Merry Christmas and Happy New Year. Hope to speak soon.
John, Nice to hear from you and excellent that you are still watching. May the silly season treat you well too.... Martin
Thank you for another very cool video. Excellent and instructive work!! Because of you and other guys like you I have started my own backyard foundry. I have a couple of questions: what is the resin that you use for the core molding and also what type of sand it is?
Mario, For these cores I buy the sand and the resin as the one thing! I.e. the sand comes pre-coated with the resin. I think its some sort of urea formaldehyde resin and its just normal silica sand of AFS 70 size. This sand known as either "shell core sand" or "resin coated sand" is available in different resin percentages and sometimes different AFS size ranges just about world wide and it is quite cheap - less I think than $10.900 for a 25 Kg bag and you get a lot of cores out of 25 Kg.... Martin
@@olfoundryman8418 Thanks a lot for the info!! Please keep feeding us with more nice videos :)
Nice work and entertaining thanks for the videos. What size mesh screen do you use for your finishing sand? The finish is awesome
Wayne, Thanks for your comment. Glad that you like the videos. The sieve that I use for the back up sand is labelled as 1.6 mm mesh but a 0.064inch drill will just pass through the mesh. The sieve for the facing sand is unlabelled but will just pass a 0.055 inch drill. Very occasionally I will use a sieve with 0.025 inch openings in an effort to get an extra fine finish but a sieve this fine is so hard to get sand through that I use it very rarely. Measuring my sand with a micrometre (silly way to measure sand!) I get a maximum grain size of 0.006 inch but most of the facing sand is much finer than this... Martin
Two questions....1. Whats the white powder for that you brush on the Sprue and feeder port? And 2. Whats the material you put over the feeder material when youre done pouring? Youre amazing at this...your cast parts look better than machined parts!
Brian, I dust the feeder and sprue cavities with parting agent it is simply finely ground calcium carbonate. I do it because it makes it a little easier to blow off any loose sand that may lodge there as I continue to process the mould. I am probably the only foundryman to do this😏. I add an exothermic powder called "Ferrux NF" it is made by Foseco to the tops of the feeders, this catches fire and generates a lot of heat which keeps the metal in the feeder liquid for longer so it is better able to provide feed for the solidifying casting underneath... Martin
@@olfoundryman8418 Awesome, Great stuff! Ive always wanted to get into this type of stuff,, not on a major level like you are, but just one off jewlery type stuff! Your channel is very informative! Thanks for the response!
Excellent video sir! I don’t suppose you could make a video on your process of cleaning out a crucible after pouring metal? Is there residual metal left?
Garth, The "sir" is a bit formal for a poor old foundry man like me. Not really much to cleaning the crucible out. If It is a smaller crucible that I lift out of the furnace to pour and that is up to an A25 size I simply empty any remaining metal into an ingot mould and before using the crucible next time I peel off and throw away the skin that always seems to remain on the crucible wall and bottom, this is mainly just oxide and I don't want than in my next lot of metal. For a crucible that I ladle out from and do not remove from the furnace I just bale it out as low as I can get the metal - about 12 mm left perhaps. When cold I remove any skin on the walls of the crucible and attempt to remove the 12mm in the bottom. Again I throw all this away as it is contaminated with oxide and sometimes heavy intermetallic particles (iron compounds etc.) and I don't want these in my next melt. Sometimes I put a piece of bent wire (a straightened out coat hanger works well) into the 12mm of metal in the bottom of the crucible while it is still liquid. Then after peeling the walls clean I can lift the bottom slug out by the wire and throw it all away. I tend to be very fussy with my metal, I pay good money for it and the results depend on it... Martin
Olfoundryman you are a wise foundry man who doesn’t seem much older than I.😂. I am 43 and I have learned so much from your videos and you have inspired me to the point that I am currently building my own furnace to start hobby casting. Thanks so much for the prompt and detailed response. Keep up the great work. I really appreciate every video you have made.👍
Garth, 43 you say, well I am a little up on that, 73! Its comments like yours that make it all worth while and I thank you greatly for them. I will try to keep the videos coming.... Martin
Hello Martin,
Love the videos. Would you do some for us at the Barber Museum In Birmingham, Alabama please?
Lee, You seem to be into the odd motorbike or two. 😊 My experience thereof was 15 minutes on a 150 cc Royal Enfield followed by 30 seconds on a 250 BSA the latter scared the crap out of me so I got off and back into the old straight 8 1934 Buick that we used to pound around the paddocks - never back on the bike again. How may I help you? … Martin
How does one get directly in touch with you? You can go to our website and send me an email privately if you like.
Lee, I will give that a trial..Martin
Great work, love watching you work. Wealth of knowledge. Hey, I’m having a UA-cam meetup this Friday at Autodesk Kilsyth office this Friday 9:30am. You and Nigel should come. Cheers Aaron
Aaron, I appreciate the comment. Nigel and I are booked in see you at Kilsyth... Martin
Olfoundryman awesome, can’t wait to meet you 👍
Aaron, A thoroughly enjoyable morning, thank you... Martin
PS. I was going to suggest that you came and had a look at my mill on your way home, 10 minutes away, but you did seem to be short of time so I held off, never mind another time.
Hi Martin. Thanks to both of your for coming on Friday. It was really great to meet you and Nigel in person. Always great to put a face to a name. Oh I would have loved to come over and check out your shop and mill, but unfortunately I was flat out on Friday. Always next time mate. Cheers, Aaron.
Excellent detail in casting . you calculate the gate runner sprue can be publishing please ?
Luis, To be honest I do not calculate the gating system sizes. Many years ago as a result of experimentation (and a little calculation) I settled on a sprue size of 8mm exit diameter and a top diameter of 14 mm (120 mm up.) This gives a taper on the sprue of 1.4 degrees per side. This sprue suits 95% of the work that I cast which includes aluminium castings of from 100 gms to around 3 Kg with most being 1.5 to 2 Kg. Occasionally I use a smaller sprue with a 6 mm diameter exit for small work and very occasionally a larger sprue with 10 mm exit diameter for work requiring a very fast fill (plaques etc.) The problem with calculation is that you first have to decide how quickly you want to fil the mould and as yet there seems to be not much in the way of a method for accurately doing this (most people fill way to quickly!). Once you have decided on that fill time its quite easy to calculate the sprue size etc. If you are interested in studying this I suggest the "Complete Casting Handbook" second edition by John Campbell. It goes into these calculations in some detail.... Martin
Great video. Did you have to allow for shrinkage on the thread? Thanks
Rupert, I would assume that the pattern maker did allow for shrinkage when he made the little core box for the threaded core. I would guess that he allowed about 1% - less than normal for aluminium shrinkage because the core box is made cold but used hot so it would get bigger and thus take care of a part of the shrinkage - the 1% allowance would do the rest.. The part that screws into this thread is fairly thin plastic and thus fairly forgiving anyway... Martin
Thanks
Thanks for sharing. What car is this for? Or is it more of a universal reservoir for many older models?
Nathan, I believe that it was more or less universal. If you Google "1955 MG TF Master cylinder" you will see the sort of master cylinder that this part was used with. Typically these were made by Girlock. Many cars (particularly British ones) from this era mounted the master cylinder under the floor. With all the dirt and dust and confined space in this area the master cylinder was very difficult to check and top up with brake fluid. PBR (a Melbourne company) produced a kit that included a casting like the one in this video, a plastic fluid reservoir, a new top for the master cylinder, and enough pipe to connect the casting when mounted on the firewall with the new top that was mounted on the master cylinder. Thus one could check and fill the fluid level if necessary without having to crawl under the car. PBR apparently made these kits from about 1954 to 1960 by which time most new cars had the master cylinder itself mounted on the firewall rather than under the floor and demand for the kit diminished. A friend (and customer) makes and sells a few of these kits mainly I believe to some car clubs.... Martin
I told you to get a base board for the cope when you went to pull the pattern, but you didn't hear me, lol
Edit: would unscrewing the core with a pipe wrench (faced with cloth tape to prevent marring the casting)seem a potentially workable core stripping solution?
Luddite, Sorry but I am a bit hard of hearing - you will have to shout louder next time!
Trying to unscrew the core would most likely result in the core breaking off level with the casting, just as it does when I first start vibrating it out. I should have used a lower resin content sand for the shell cores... Martin
ill endeavor to project more in future, lol. i kind of figured the breakage was "why not", but a question unasked is an intelligent reply unheard
Thank you for another excellent video.
Thomas, No worries mate thanks for the comment.... Martin
Nice. Where do the core boxes come from? When a customer orders a part like this, do you need to spec out the core or are details like that given to you? Do you store them away for future use or are they usually a one shot deal?
Brandon, For a new customer I will discuss what I need in the way of patterns or core boxes. Basically the customer details what he wants in a casting and I detail what I need to achieve that. However generally I work with a small group of return customers and much of the work comes through a tame patternmaker (the wild ones are a worry). He and I have worked together many times and each of us knows what the other needs to get the job done. We have great respect for each others ability and know well how to work with each other. Together we come to a mutual decision as to what sort of pattern and core box set up is required. For one off type jobs we often use Silicate CO2 cores as they only need a simple wood core box. For work that is going to repeat more than a few times we will go to the trouble of a metal core box and shell cores. I much prefer shell cores. Sometimes, for shell work, I will cast the (aluminium) core box pretty much to size and shape with only the mating faces and dowels needing machining, other times he makes the core box from aluminium plate. He is damn good at this and very quick too. This was the case for this casting even though only fairly small numbers will ever be required (about 20 so far). Here a CO2 core would not have been as likely to produce as good a thread so we opted for the shell core, he made the core box. Regardless of job duration or core type one of us (usually me) will keep the patterns and core boxes in case of future use even if we think it a one shot deal as it is surprising how often a "oncer" turns into an "againer" when someone sees the "oncer" and says, Hey, I would like one of those! Never throw a pattern out!... Martin
Awesome video Martin 👍🏻👍🏻👍🏻 thanks for sharing. I've noticed in the past you would make shell cores curing the surface area only and dump out the inside to save on mass, just curious why you didn't do that on these
Clarke, They are too small, below a certain size range the tip out trick does not seem to work all that well. I guess its something that you just have to do to get the hang of. Not only does it save mass but it also shortens cure time, bigger cores if solid would take 5 to 10 minutes to cure right through and then you would never get them out of the casting. The good breakdown of shell cores depends a lot on them being thin and hollow....Martin.
Nice job and great video
Nigel, I aim to please, thank you for your comment... Martin
FASCINATING - forgive my saying this but it all looks a bit archaic and slapdash as the moulds are being made up, but the finished results are astonishing. I wouldn't have believed it was even possible!
Stony, It is most definitely archaic but there is method in the madness and what may appear "slapdash" is very much a methodical process just carried with the speed born of a lot of practice... Martin
Another cracking bit of work!
What binder are you using for the shell cores?
Tris, The shell cores are made from a resin coated sand. I buy the sand already coated. It is a product available like this very widely (world wide I would think). The manufactures add the resin to the sand and with the aid of some heat coat the sand with the resin. As far as I know it is a type of urea formaldehyde resin. I use two resin strengths 2% and 4% but I understand that you can pretty much buy it in almost any strength. The 4% is quite strong and any stronger and it would be very hard to get out of some castings. For work where I need a very good breakdown for difficult to remove cores I use the 2% but mainly I mix 2 of the 2% with one of the 4% and effectively make a 2.67 % blend which seem to suit most of my work. as a core making process I highly recommend it suitable for nonferrous and ferrous alike... Martin
Thanks for the reply Martin, is the resin a furan type? Don’t suppose you have a product name for it?
Thanks again for the detailed reply, much appreciated!
Tris, No, I don't think it is a furan, that's more the Fenotec type process used for whole moulds by much of the foundry industry these days i.e. the so called "hard sand". I don't have a product name for the resin I simply buy the sand as "Resin coated sand" and the manufactures of it do not state the type of resin but a bit of "Googling" suggests that it is most likely a Phenolic resin. It seems to be known simply as "resin coated sand" world wide, sorry that I could not be of more help.... Martin
That’s great thanks Martin, I’ll have a hunt round for resin coated sand here in the uk, anything furan based seems to be unavailable to us backyard guys over here!
Thanks for your help, keep up the awesome work!
Tris.
Problem with the furan stuff is that Foseco et.al. like to sell the binders in 44 gallon drums! You could try a smallish local foundry and see if they will sell you some from their drum for cash. But considering the problems of proper mixing the two (I think its two) chemicals into the sand and then the few minutes of working life after mixing, I think you would be better off with silicate CO2 if you really want to play with hard sand moulds. For cores like this job uses though and provided the quantity of castings required justifies the expense of a metal core box I would always prefer shell sand cores. If you do try silicate remember to add 1/2% glucose powder to the mix or you will be breaking the mould off the castings with a jack hammer! With the glucose you can wash the mould off with a hose..... Martin
I'm looking for someone to cast a 1960's McColloch chainsaw piston, if this reaches you are you still casting? And can you be contacted?
JT, Sadly I am currently in no fit condition to cast anything, so while I would love to be able to help you I cannot. However I can put you in contact with the foundry who has taken over my work and can even supply them with the correct alloy for pistons (hard to come by here in Australia). If you wish to make contact with them email me at olfoundryman@gmail.com .... Martin
Excellant video...!
Rich, Thank you... Martin
What do you add to the sand that makes it harden with heat? I've seen this on a few videos.
David, I do not add anything to the sand. It has a half cured phenolic resin added by the people I buy it from. The heat first melts and then cures this resin to a hard bond. You can get this sand world wide under the name of either "resin coated sand" or "shell core sand". It comes in various resin strengths typically from 2 to 4 % and it is quite cheap...Martin
@@olfoundryman8418 thank you. makes sense now. :}
great results mate! thanks for sharing :-)
JB, As always sharing is my pleasure. I am still waiting for you to put in an appearance in Victoria .. any closer?... Martin
A core wash would give you a better finish on the threads.
Surprised you didn’t vent the core.
Ross, Yes, a core wash sure would have helped. The core sand is 70 AFS and I long for the 90 AFS I used to be able to get (sigh!) I have used a wash on similar threads - see here ua-cam.com/video/lNxwrSzm9q8/v-deo.html but on advice from the customer did not bother on this occasion. I guess he was right as the mating part screwed in just nice. On thing I like about shell cores is that being dry they do not out gas as much as say CO2 or normal sand does particularly when metal sections are thin (like here) also they are almost always hollow - even if you have to poke a hollow in them 😏 - this makes them self venting. I could have vented from the core prints but with so little heat going into this mould I felt it unnecessary to do this. In truth I don't think I ever vent shell cores. CO2 cores - different story I vent the hell out of them or they blow every time!... Martin
Awesome job thank you
Victor, Thank you for your comment... Martin
Very nice I just got into sand casting myself with small amounts of aluminum that is and that you're able to cast those threads being at their large Real fine threads wouldn't pick up well in the sand
Brian, Yes, I would not want to try a thread much finer with this shell core process. But it is surprising just how fine a thread one can cast in a fine green sand. I have cast 3/8 16 tpi Whitworth threads in bronze by using a bolt as the pattern, rapping it in the mould a little to make it slightly bigger. The parting line comes out a little rough but quickly running a die down the cast thread fixes that up.... Martin
Olfoundryman oh yeah one more thing to be able to make the sand solidify is there sodium silicate or something added to that sand?
Brian, No, there is no sodium silicate added. The shell core sand that I use to make the threaded core is coated with a resin which cures off and causes the sand to bind together when I pour it into that little aluminium mould which is heated to about 180 deg C. The heat first melts and then cures the resin. The sand has been coated with this resin by the people that I buy it from. It is simply known world wide as "resin coated sand".... Martin
how do you make this kind of sand for core?
Joao, I did not make the sand. It is a natural moulding sand that came out of the ground. All I have to do is sieve it to remove the few larger pebbles that it contains. I then add the required amount of water and its ready to use. I do have a couple of videos on sand preparation. One shows how I prepare my facing sand from this natural material and the other shows how I reprocess the sand at the end of each days casting... Martin
@@olfoundryman8418 Martin, ok thank you Martin.
Joao, I am sorry but I misunderstood your question. The sand core is made from resin coated shell sand. I use a little aluminium two part mould for the core. This mould is heated to about 180 deg C and it is quickly filled with sand the heat cause the resin coating on the sand to first melt and then cure to a hard bond, after about 2.5 minutes I pull the two halves of the mould apart and remove the core. I don't make this sand myself as it is a bit of a complicated process I buy it already resin coated. It is quite cheap and is usually simply called "resin coated sand" or "Shell sand" It is usually available in different resin contents, I buy two grades one with 2.5% resin content and the other 4% resin... Martin
@@olfoundryman8418 thank you Martin for your answer, i'll try to find this sand !!
Smooth awesome!
Jim, Glad that you liked it - This was actually an easy little job made al the more interesting by that threaded core... Martin
Never seen this before
Paul, Most of it was fairly standard stuff - was there something in particular that you thought unusual … Martin
roller beaing ball mill polishing
Hi Martin,
Another great video ! Just wondering.... is it possible to make silicate shell cores ? I'm aware that if it is it would be restricted to very simple ones.
Thanks in advance Dick
Dick, Well I guess that you could. Just have a mould with a loose core piece that is placed in the centre of the CO2 sand as you place it into the mould, cure the core off and then remove the core piece thus producing a hollow CO2 silicate core. Sort of a core within a core process I guess. As you say restricted to simple shapes. Don't know if it would be worth the effort, it would make core removal after casting easier but 1/2 % glucose powder in the silicate mix does that anyway... Martin