Metal Casting Tips and FAQ

Frequently asked questions

I enjoy answering your question on my Youtube videos and have put together some of the most frequently asked so I can answer them in more detail with the aid of illustrations.
Feel free to ask anything that is not clear.


Where does your user name come from?
Nothing to do with the Ford Motor Company, my lathe is a Myford, Myford lathe, myfordboy!

Can you recommend any books on casting?
I can recommend Foundrywork for the Amateur and The Backyard Foundry, both by B. Terry Aspin. I bought these 2 books when I first became interested in casting and they gave me a good introduction to the craft. I also have  The Complete Handbook of Sand Casting  which is worth a read.

Can the sand be used again?
Yes. With the greensand I am using I let the sand cool and then pass it through my Super Sifter
A little water is sprayed on to get the moisture content back to a usable state.

How is the core located in the centre of the mould?
From the amount of enquiry's I get it is not clear how the core stays in the correct location when the metal is poured.
Shown below are some snapshots from my Metal Casting at Home part 10 video.


Here we see the split pattern. Note that on the ends of the pattern and at the top, some half round sections have been added. These are called CORE PRINTS and will not be part of the finished casting.

When the two halves are  placed together the half round sections form a full round section. 

This is the core. The round section at the top and at each end will locate in the core prints in the sand mould. Because there are three it can only be positioned one way.


                     The core is lowered into the mould.




The core prints hold the the core in the centre of the mould.



  On the finished casting the core can be seen at each end and the core is then removed by soaking in water and digging out..











75 comments:

  1. Very interesting videos, casting, machining and building your own engines from scratch. Are you passing your skills on to young people (apart from through Youtube)?

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  2. Regretably I know of no young people who are interested. I am a member of a model engineering club,I'm almost the youngest.

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    Replies
    1. I am young and i have been watching you do this stuff in awe!! I would love to make stuff myself thus is the reason i have been watching you! Thank you! I am looking to make small things first then who knows! Thanx again

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    2. Thanks a lot for sharing an informative post as I was looking for aluminium plate suppliers and found your blog very useful.

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  3. hmm.. very great and inspireing tutors on youtube thank you. id like to try it. but i dont know how to build a stove. did you used fireproof cement inside? and when you supply heat, how come supply tube doesn't melt aswell. how to get heat 1000-1300C at home? is that a simple gas balloon you are using or any special one? how do you measure temperature of flame and temperature of inside gasses in stove? if you could make tutorials on that.. that would make all your tutors complete and whole.
    thanks :)

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  4. Not sure what you mean by gas baloon. Fuel is propane gas in a bottle. The end of the burner is not in the flames so it doesn't melt.
    Click on the link to myfordboy's furnace for details of the construction(under "Pages" on the right of this page). Temerature can be measured with a thermocouple connected to a meter. With the aluminium I just pour as soon as its melted, it can be overheated.

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  5. Investment castings are the most versatile metal forming methods available. Designers are not limited to any particular alloy, as the investment casting process allows for easy alloy substitution using the same tooling. Great post!

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  6. Don't worry there are some young people. I'm one of them. I have to get some linseed oil to try your core recipe for several cannon patterns I made. I have a site as well. http://maniacmechanics.blogspot.com/

    Great work with everything.

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  7. hello, im 17 and i love your tutorials, i currently work part time for a small engineering company, and go college studying areospace engineering. i love the way you show the vids step by step kepp it up matey.

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  8. @Bill T
    I have read in another book that you can use molasses instead of linseed oil, which would make it less toxic for use in the home oven, and not anger your mother/wife/girlfriend.

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  9. hello im 26 and thinking about casting
    too hit or miss little one
    yep got to say found videos very intresting

    got a few question if u dont mind
    how long dose it take to heat that amount of alu up with propane and is the a ideal temp to aim for ?
    just thinking about veg oil burner thats all
    get that it harder to regulate just like the waste oil burner hotter it get thinner the oil fast it flows
    and hole on furnce very large too on yours ?
    was thinking 55 gallon drum cut up with empty propane bottle cut in half and nice think insolation walls keep the heat in

    casting sand
    well have kiln died stuff use with shot blaster vessel just thinking of how fine to go what do u sieve at mirco ?
    also have very fine glass bead and chilled iron just a though
    is there a point were its to fine and dose to holds together ?

    i have almost finished my 8 x 4 cnc plasma cutter but can fit router in so was thinking of molds were did u get spec from thinking cold night in out of garge running it up on cad ?

    oo did u make up the boring bar one u used end to end to bore cyclinder ?

    the mant prob at mo dont have mill at mo but thinking angle block and flycutter on lathe
    or think not possible have a fair bit of cross travel

    sorry my grammer is bad
    Dyslexia as they come

    many thanks dean
    mini_mad_dean@hotmail.co.uk

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  10. It takes about 20 minutes to melt 5Kg. I pour as soon as all the metal is liquid, I don't measure the temperature. It bad to let the metal cook you can overheat it.
    The sand needs some clay in it to bond together so what you mention may not be suitable.
    Boring bar is home made.

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  11. I know this will appear foolishly simple in retrospect however, I am still in need of the easiest way to make green sand. I have read a bit about it but still it seems oddly confusing. Should I just go down to the beach and pick up a few hundred pounds of sand and sift out the seaweed and other things and then simply add a 20% by weight floor dry(Diatemaceous earth) and mix well with a little water? Or what?

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  12. My sand is a foundry product I have never made my own. The recognised method though is to use play sand and up to 10% bentonite clay. It needs to be mulled, it is not sufficent just to mix it together. Failing a proper mechanical muller its possible to put it between sheets of plastic and walk/drive over it until every grain is covered with the clay.

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  13. i have a question that in the making of stirling engine..if balsa wood is not available then what should i use as an alternative

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    Replies
    1. Bass wood is a common alternative to Balsa wood. you should be able to find it in most every hobby store beside the balsa wood.

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  14. Balsa is ideal for this engine as it needs to be light but heavy enough to fall under its own weight. Anything heavier, like a heavier wood, would effect the engines performance. I can't realy suggest an alternative as I haven't tried anything else. Foam would not stand up to the temperature inside the tin.

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  15. I found second video very interesting as you can really learn some good things from it...you can actually learn the process easily by watching it.... definitely things gonna be difficult if you try this for d first time... but this post will help you somewhere.... Bronze foundry

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  16. How many heats do you get out of your stainless steel crucibles. I am thinking they would last longer in an electric kiln type furnace which I plan to use.JP RYAN in California

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  17. It varies how long the crucibles last. I can get up to 10 melts usualy. An elecric furnace should prolong the life as there is no flame involved. Heating would be more even.

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  18. Hello myfordboy and thank you very much for taking the time to share all of this with everyone.

    I am a complete rookie at this but am very interested in casting my own stainless steel designs. I am trying to do a Shiving razor and brush stand out of solid stainless steel. I aim to keep it as more of an art project than anything but I would like to make about 20 of them to give to friends and family. Which approach do you recommend I take?

    I am fairly certain I'll be able to make the mold myself but I may have to take it somewhere to get stainless steel poured into it. The sand seems tough because you need to rebuild it every time. Is there another type of home maid mold that you can re use over and over again? I've made molds out of rubber for making plastic prototypes and would love to make something similar for stainless.

    Thanks so much!

    Edward

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    Replies
    1. I would suggest lost wax casting is the way to go with this one.You would need to mahe a female mould to produce the item in wax. In industry this would be an 2 or more part aluminium mould. You will not be able to melt stainless steel yourself but you could produce the wax items and get them cast at a foundry that does investment casting.

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    2. Great! Thank you so much!

      Edward

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  19. Are you making your own wood paterns if so please do a VIDEO . This is the only thing that is holding me up at this momment.

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    Replies
    1. I have videos on pattern making like this one.
      http://www.youtube.com/watch?v=-sQCJ6rv54s

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  20. hi i wonder if you can help, i have a foundry (home made) it works great but i keep breaking the mould when i remove the patern. is my sand too dry? when i had sand sticking to the patern i was told my sand was too wet, but the mould would not break. any advice would be great

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  21. Does your pattern have enough draft? If it has then its realy only your sand mix that could be wrong.
    I have just put out a new video showing how the sand should be.
    http://www.youtube.com/watch?v=l638qR0Y6YE

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  22. Good morning,

    The E Z stirling engine page is missing from your site.
    Could you please check?

    Thanks

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  23. Good morning Myfordboy,

    Thanks for all of the videos! We're starting to do some sand casting in a highschool shop class and I have a few questions about the sand. We're using a casting sand that has been mixed with motor oil. Should this oil just be a 30 weight crankcase oil? I would think that we're looking for the same consistancy that you're using with the watered sand. Is that correct? I'm also curious about the alignment pins that you're using on the flasks. Are those something that you fabricated or are they sold? We were thinking about building some small flasks like you have. We have some aluminum ones, but they are pretty big and need a great deal of sand. Just FYI, some of the kids are really interested in this, so your videos are helping to pass it down!

    Thanks again

    Once

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    Replies
    1. I am pleased you have enjoied the videos. I have no experience with oil bonded sand so I can't help with this one. There are full details about the alignment pins on my " Making Moulding Flasks" page.

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    2. Your tips are fantastic and I am sure it will be useful.
      Aluminium Suppliers UK

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  24. Re the Stickney and the 2 pieces of aluminium that you removed by chain drilling. I'm assuming that it would have been quite feasible for you to make the core so that you cast those 2 holes as you went, but you chose not to. Just wondering what the pros and cons are there.

    Thanks for all the videos, they are enormously helpful.

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  25. As you say it would have been quite possible to use the core to make the hole.
    The core would have been more complicated to make and the pattern would have needed additional parts to accomadate the core. The additional parts on the pattern would have to line up exactly with the core. This was my reason for using the method shown.
    Glad you like the videos.

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  26. Great site, great videos !
    I have been doing some aluminum melting for a few years (gingery lathe for instance). I have tried experiments with pure aluminum in which I left about 4% in wheight of pure coper (old electric wire) which is I should say "absorbed" in about 20 minutes by the melting aluminum. It seems to work not so baddly, and the alloy is "useable".
    I have seen that you use salt or diet salt to improve the fluidity, and washing soda as a degaser. Could you explain the chemistery of that?
    Thanks a lot (an apologies for my poor english)

    Claude

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  27. Hi Claude.
    I don't know the chemistry other than the washing soda drives off hydrogen gas which is absorbed into the metal during the melt.
    I have heard of adding copper to make it more machinable, I must give it a try.

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  28. Hi Myfordboy ... For the degassing can be used sodium bicarbonate in place of sodium carbonate?

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    Replies
    1. I am no chemist but sodium bicarbonate is obviously a different ingredient so could have different properties. I know the Sodium carbonate works so why not stick to this? Some users use "pool shock"for degassing.

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    2. Using "pool shock" is chlorine and can create deadly chlorine gas. Please use this meathod in well centilated areas. But better yet, google Sodium Carbonate or washing soda and see that you can buy a box for a few dollars or pounds.

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  29. Brilliant, I love it. Never had the opportunity at school or college, but you make it look *simple* thought I am sure it is not. I have built the furnace and tried it out last Sat, worked a charm. Plan to buy some green sand and make my first mold. Thanks for all you have done

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  30. myforgeboy
    what can i say i have been inspired by your video's to start my own forge so far i have i have only built a coal furnace but it still aluminium.
    i was wondering what i can melt in the gas furnace ie: mild steel, copper, brass any ideas as to what i can smelt
    thanks and keep up the good work
    dingo.dynamo@live.com.au

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    Replies
    1. The design is good for melting aluminium, brass, bronze copper but to melt cast iron the refactory lining would need to be replaced with a higher temperature one. Mild steel is not suitable for casting.

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  31. Hello Myfordboy,
    Do you have to do anything to your greensand after casting parts? Do you just bust it up and add it back to the unused greensand again or dose it dry out to much to use again? Thanks

    Joe

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    Replies
    1. I just push it through a kitchen sieve and then add water to get it back to the correct moisture content. Have you seen this video?
      http://youtu.be/mNDliDKH7Hg

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    2. Just watched part 26 and came back to say I found answer in that video but you where already on top of that...."Look with your Eye's not your Mouth " Thanks

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  32. thanks myforgeboy
    for the reply about what i can smelt and if i need to build a furnace with a better liner what would you suggest that i use as i have a coal furnace and am about to build the gas furnace any help or advice you can give me i would be very greatfull and thxs for responding so quickly bloody impressed i am lol

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    Replies
    1. You don't say where you live but you need to get a commercial castable refactory to make a hot face if you want the furnace to withstand higher temperatures. I have not used this myself. I can send details if you email me.


      Message to all--
      If everyone signs themselves as Anoymous I don't know who I am replying to.

      Delete
  33. hey myforgeboy
    sorry that was me asking about the lining in the question above .
    i'm an australian living in melbourne and have just started in this new adventure i need to caste a cone with a screw on it apperently its very hard to turn on a lathe so i was hoping to caste it . its for a wood splitting machine i want to build if you can send those details i again will be very greatfull and promise to give you some feed back as how i go
    dingo.dynamo@live.com.au

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  34. Hello Myfordboy,

    I,ve watched your entire series of videos on youtube with very great interest. I assumed that you had spent your entire working life in a traditional UK skilled engineering/manufacturing environment, sadly a thing of the past and with it the apprenticeships that gave young men an opportunity in life.

    I work in I.T. an interest that I developed at about 35 years of age and taught myself.

    I have some technical questions.

    How thin can a casting wall be made?

    What is the limit in terms of overall dimensions of the casting?

    When you have a molten mix how much time do you have to get it in the mould before it starts to solidify with the possibility that the material won't flow properly?


    I am interested in environmental issues, alternative energy and recycling. To these ends I have a number of projects in mind, do you have an e-mail address could I send you my designs and ask your advice?

    Thankyou so much for making the videos, quality!!!

    Kind Regards
    Peter

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    Replies
    1. Hi Peter,
      None of my working life has been spent in the environment you mention! The engineering is a hobby and all I know has been learnt from books and self tuition. I have been a model maker since school days and have progressed via model aircraft, and cars to model engineering.
      To answer your questions,The thinness of the casting possible will depend on the size of the object. I suppose I have gone down to about 3mm on small pieces.The overall size depends on how much metal you could melt in your equipment. I can melt 5Kg with my set up. The overall size is not an issue if you can melt enough metal to fill it, the mould will hold good.
      There is enough time not to rush the pour, it safer not to hurry, no real danger of it solidifying before you pour.
      I am happy to help if I can. myfordboy[at]yahoo.co.uk Replace the[at]with @

      David

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    2. Hi David,

      The result of your self tuition is very impressive!

      Two more technical questions.

      When you break the molds, do you reuse the sand or is it too cooked to be used again?

      Do you factor in any shrinkage for your designs?

      Peter

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  35. Peter,
    The sand is used over and over again. I make the patterns 2% larger than I want the finished item to be.

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  36. Hi i noticed a few things

    When you pour the metal in - how did you make sure the metal did not fill the metal tubes you were pouring it into? (because if it did that, it would match the shape that we want) like how did you make sure you had the right amount of metal?
    Also, if you were to do this often where can you find a ready supply of metal? is it just builders merchants and so on? Thanks!

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  37. sry in my first question i meant as in if you have too much it would "over spill" and then form the shape of the tubes too

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  38. It is necessary to fill the feeder and riser tube as this gives the metal head to fill the mould.This is the reason for adding the extention feeder and riser. As the metal cools it shrinks and this head of metal feeds the mould. You can see the metal shrinking at the top on some of the videos.
    I have never bought any metal just keep my eye out for scrap like car parts old light fiitings etc.

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  39. I have entered the realm of metal casting because of your You Tube videos. I have to admit, it has been a complete failure. Hours and hours of frustration each day for the last two or three weeks. I'm obviously doing something quite wrong so I hope you can help.

    I notice you now have a reference to a company selling green sand. Prior to that you had another company but they had red sand which, with the conditioner I bought from them, was said to be right for the job. I have called them several times for advice but I think it is something wrong with the way I'm using the sand. They admit it is not as good as the old Mansfield green sand but I'm sure it is something I'm doing wrong.

    The thing I'm making: I have a brass ferule welded to a 3mm brass plate which is oval shaped. The plate is wider than the ferule diameter by 4mm and 10mm (because of the oval). The welding has been done by an expert friend of mine and it is perfectly smooth. I'm a wood turner so I have turned a 480 gritted piece of box wood which fits inside the brass ferule. I place the object on a shiny piece of contiboard that is perfectly clean and dry. I have made a frame that I put around the object which is plate down and ferule up and with the 'bung' inside the hollow (the sand gets stuck in the pattern otherwise). I put the frame around it and pack in the sand very tightly as you show. I then turn over the 'box' and tap the pattern. I then screw in a couple of screws in to a couple of pre tapped holes on the plate. I lift the pattern an the bung remains behind as I planned. The mold is damaged in some way though. Usually it is the sand sticking to the pattern even though I talked it thoroughly. I then try drier sand but it wont pack so close and I get some gaps but it doesn't stick to the pattern. So, I either have gaps or stick and there is no in between those two states.

    My question is: Do I leave the sand to dry/harden for a long time (if so, how long) or should I go to even more expense and buy the new sand you are recommending. I live in Sheffield, South Yorkshire so I can get to most of the places you might know.

    My second question is: Should I abandon the sand altogether? I need to make about fifty of these objects and it would be a fag to make a new batch of sand every time, or could I keep pouring in to the same sand mould once I get a good one (not holding my breath though).

    Sorry for the long post but I'm feeling quite desperate at the moment.

    Kind regards,

    Graham.

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    Replies
    1. Hi Graham,
      I was often asked where to get greensand and J.Winter & Co was the only place I had seen it for sale although I had not used this sand myself. I recently came across ths Artisan Foundry site and as I needed some more sand I thought I would try theirs as there was no minimum order and they seem to be geared up to supply us home casters.
      As supplied the sand was very wet and it took a while to dry it out enough to use. I had to go over it with a hot air gun as we haven't seen any sun this year otherwise a day outside would have done it. It took me a few goes to get feel for it as it was a little different than my usual sand. Video No 29 shows this sand in use.
      Do have any draft on your pattern? All surfaces should have slope to enable easy withdrawal so the furrule need to have a slight taper on it. Realy if the sand sticks to the pattern it's too wet and if it breaks it's too dry. Did it pass the sweeze test, not sick to hand but break cleanly?
      You can't use the same mould for more than one cast as you need to break the sand to get the casting out.
      It does take practice to get the correct moisture content in the sand.
      I see Artisan Foundry do casting courses at a reasonable rate.

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    2. Thanks for the speedy reply. I think I need another casting method. Originally I turned all my 'tops' by hand but they became moist with the sand so I painted them and then they were not so smooth as when I'd turned them. The sand always seems to stick. I did notice the courses and I might go on one but I'm a bit disheartened by sand and wonder if it will be more money wasted. I'll bite the bullet again tomorrow and try hand drying like you suggest. I think it might have come too wet in the first place I can turn slopes but the ferule is perpendicular to the lid and that corner is where the problem always occurs. I'll turn some sloped ones and try again - thanks.

      Delete
    3. Graham,I would suggest a radius on the corners too where the ferrule meets the plate if you don't have one there.

      Delete
  40. Thanks for the nice blog about casting metals. I found it very interesting while reading. Aluminum casting is done in different ways mixing different alloys. Aluminum sheets and wires are widely used in markets and found in abundant on earth crust.

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  41. Thank you for such excellent videos. I have recently retired and have purchased a small lathe and mill. I finished my furnace and I am waiting for the liner to cure. I noticed that in your early videos of casting you spend a lot of time on your knees in your workspace. I would imagine that the local vicar could not match you with time spent on your knees. This must be rough on you as well as the knees of your britches and as well as the toes of your footwear. Keep making more wonderful videos. I will be watching and learning.

    Thank you,

    Dusty from Arkansas USA

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    Replies
    1. I like to make up the moulds on the floor as it's a nice firm surface. It also means I don't have to lift all the sand up to a bench. I am used to working on my knees all my working life as an electrician and have knee pads in my trousers.

      Delete
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  44. Hi Thank you for the videos you produce! Very informative. I had a few questions if you don't mind. 1)Can the greensand mold be used again after the first molded part is done, another words, does it hold it shape to be used for a second , third use? I'm trying to make a mold that I can pour lead into similar to an water in an ice tray, to be used repeatedly. If green sand doesn't work for second and third tries do you have any ideas on making a mold that does that does not require special shop tools, etc.? Thank you ! Bob

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    Replies
    1. You can only use a sand mould once. It will breakup when the casting is removed. If you want a reusable one it would have to be metal ans possibly hinged to get the part out. Something like this is used to cast fishing weights.

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  45. Thanks for the nice blog and all the useful information i will keep in my mind, hope you the best. Brad

    ReplyDelete
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  51. Interesting blog. We are visiting an aluminium factory in India as part of our industrial visit and was looking to read material on some related products. Should buy the books you've recommended to get a better idea about castings; would like to be well informed before my visit :)

    ReplyDelete
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