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08/08/2010 10:27 pm
Lead question.
To clarify matters somewhat, there are many lead alloys available from metal suppliers. The choice a caster has to make is what is the best alloy for the job in hand. Different alloys have different properties, some are great for large thick sections but use less for fine detail, some are great for detail but are useless for thick sections. Many years ago I had to produce some jewelery products for a customer. The product had to be cast in a flat form and then bent to shape. The metal I used was almost a pewter at least 95% tin. Subsequently I used this rather expensive metal for casting models. Apart from the safety aspect the benefit was more models per kilo of metal,therefore lower postage costs plus parts that got bent could be straightened without cracking.
Lead fumes are dangerous and should not be ignored. Short of eating or drinking from a lead product (crystal) on a regular basis you are not in any danger. The lead in your body has probably been absorbed many years ago from breathing in fuel fumes before they removed the lead from petrol(gas). As far as I know it can be a leachate in crystal but it does not sublimate from objects.
09/08/2010 11:33 am
added to post. .Hello Mr. Price. Thank you for taking a moment to add to the discussion about white metal casting. You are the champ. I surely do appreciate it. Do you think that it is better to use a higher lead content white metal for casting big chunky parts like bodies and then a higher tin content for castings little parts? I thought that the reason they did that was for fiscal reasons rather than technical ones??? Just to save money. I have used both the 60/40 and the 70/30 for parts and bodies. I like the 70/30 best because it has a nicer aspect. I have not tried any other white metal. Does the non lead white metal crack or have other issues?? I want to try it- am I going to waste money and time?
We have admired your work for years and your Auburn Cabin Speedster is the only non-race model we ever bought because it was so nice.
09/08/2010 11:41 am
Mr. Price did you do all those MiniMarque Models for all those years?
We think the world of your work.:)
09/08/2010 11:49 pm
Casting metal
I cannot speak for other producers as they will have their own preferences to the alloy they use. In the early days I used an alloy refered to as thirtyfour and a half (34% tin), which a fairly common alloy. However I found that on some models I would get surface flaws which needed extra work to rectify plus some of the delicate parts would not survive in the hands of the plating companies (either broken or bent) Because of the reasons previously mentioned I changed to the 95%+ tin alloy. I found that you could cast thinner sections with little or no difficulty other than upping the spin speed because of a lower density. The current cost of a kilo of the two alloys mentioned in the UK is ?8.50 and ?14.00 plus tax respectively (assuming you by 25Kg at a time). I am currently using a 34% alloy as the tin prices have gone through the roof in recent years. Re your last question this could be due to various factors. 1 casting temp too high. 2. Insufficient time allowed to cool. 3. Mold flexing. 4. Cross section too thick for the alloy used.
It took me 2 years of money,time and experimentation to arrive at succesful castings in the late 80's and I'm still not happy now! You could try buying some tin sticks to up the ratio and see how it goes. Tin is very maleable but can be hard to work (files don't last so long). With a stick of tin if you bend it, listen, you will hear it 'cry'.
Re. the MM cars we produced all the Auburns, Duesenburgs and Cords except one, the 1930 L29 cabriolet.
10/08/2010 2:00 am
lead, tin, etc.
Graham: Thanks for taking time to add to our knowledge about this complicated process. I'm always interested in knowing more about the background of producing our cars.
10/08/2010 6:23 am
Yes, Thank you so much Mr. Price. I know what you mean about spending two or more years of trial and error to figure something out and still be learning. Sometimes all it takes is someone else who has done it before with success to just tell you and save you all that time. Much appreciated. You are a treasure.