Home gas fired furnace

Stop press: I have yet to see if it works but have used some small foam letters from Staples as suggested via the website. Story below.

Index:

        1     21st March 2010 - First Casting
        2     27th March 2010 - melting of 4 scrap car pistons
        3    10th April 2010 New letter for pattern -thin from Staples.

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21st March 2010 - First Casting

Well the idea was to make some aluminum sides I could use for the moulding boxes. It seemed a good idea and I thought I would add the website name to see how easy it was to produce cast in letters. In the end it didn't work out too well. There was sand stuck between some of the letters and I put this down to the closeness between some of the characters. I did try to mould it again but without success so since this was a trial, first casting and non critical, I went on and made a melt.

The results were both good and bad. Good that the whole process went (other than the lettering) as it should. The calculator I produced in excel proved very accurate on this first occasion and the finish on the casting was as good as the pattern allowed!.

The letter failure will be explored further and I may well try just spacing them out or make a new set, perhaps from wood.
I do need to make an aide memoir since I keep forgetting to talc up! Also I need to produce 8 for each box and each different size and where and I going to get that much metal! It would seem to be more efficient to just use wood and make the set up to size as and when. If you have a large stock of scrap alloy then perhaps it may be worthwhile.

I intend to have a go at using foam for a pattern which is burnt away by the incoming metal.

Stop press:

I should have sloped the sides of the letters on my first casting and or made them much thinner (thanks to both David and Andy for there swift comments). David (Myfordboy) also suggested the use of dyno-tape for the relevant application, works well. One of the sets of Seal castings I am working on does indeed make use of dyno-tape to good effect.

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27th March 2010 - melting of 4 scrap car pistons

I did not plan to do a melt today and this led me to break a rule I am trying to employ, namely not to melt aluminum unless its the first task of the workshop session. I made this rule for safety really since my stamina fall off during each session however for some reason I ploughed on and whilst waiting for the paint to dry on my home made long handled dustpan project.

I made a further misjudgment by starting the furnace before I had prepared the mould! The first pistons (crucible held 2 pistons at a time) had melted before I had finished preparing the mould. Not very efficient and a rollicking to myself was duly given. That said I did manage to produce a bar with reasonable finish made from this high quality alloy. Whether it proves to be of any real advantage in use time will tell as how machineable it is.

When moving the bar after it cooled was a bit of a surprise in regards to its lightness. I will have to compare it properly but it does seem to be very light.

I will mark the metal poured into the angle iron mould, to ensure I can trace its source and with the sprue's to be re-melted, I should have more than enough for any future 'small' engines I make. Of course this depends on how it machines.

This melt was also the first time I used 'Losalt' as the salt additive. The reason for using Losalt instead of normal table salt is the make up of Losalt which has a lower melting point. the composition. David (Myfordboy) gave me the tip "...I used Losalt in place of regular table salt. you can get it a supermarket as a salt substitute. Its 66% potassium chloride and 33% sodium chloride. I think the metal quality was better and it machined better."

When looking at the furnace lining it seems to be standing up very well so far, so that's good news.

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10th April 2010 New letter for pattern -thin from Staples.

When the failure of my aluminum casting with letters happened I was 'reminded' that the profile of the letters would have benefited from having sloping sides. Additionally they were too thick perhaps....So I found some slimmer foam letters in Staples to see if that will make a difference.

I must admit that I did not consider this thickness of letters first time around since I thought they would not stand out enough so it will be interesting to see the results.

I decided to cut up the failed first attempt casting, for the next pour which will take place tomorrow perhaps. I have made a rule that I will only melt metal in the early part of one of my workshop sessions for safety sake. So will will have to wait and see.....

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