Thread: Wax Chuck !
14th Sep 2018, 07:40 AM #1Most Valued Member
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- Aug 2015
Wax Chuck !
I came across some posts on another forum a little while ago describing a "Wax Chuck" ! I must admit I had only heard of them, but upto this point never seen one. After reading about them and how versatile they can be, I decided to have a go making one and having a play with it.
So having a suitable off cut from an aluminium bar 65 mm in diameter I put it in the lathe three jaw chuck and faced it off on both sides. Now since the off cut was only about 20 mm thick, I machined a step about 5 mm deep for half the thickness.
The hole in the middle was a leftover from its previous life. It plays no part in this ! And those machining marks on the fact are not mine either. They were one of the reasons it got faced off.
This is how it looked when I had finished machining it. The step allows the chuck to be sat square up against the chuck jaws.
Now I can almost hear your thoughts ! Where is the wax ? There is non in sight.
The idea behind a wax chuck is so thin items that you wouldn't normally be able to machine, can be. It works like this, the material to be machined is secured to the face of the chuck with some kind of adhesive, in this case shellac. Now shellac will melt at about 90 to 120 degrees. By heating the chuck and coating it with shellac, the object that you want to machine can be securely attached.
Now I must confess that I've occasionally used super glue and double sided tape to stick items to the faceplate so that I can machine them, in particular, bronze thrust washers that have to be thinned and making sizing rings to fit in the bore of saw blades. I also understand that horologists use wax chucks for making watch and clock parts.
So I thought I would have a go !
I had some 2 mm thick brass sheet off cuts, so I cut a piece slightly larger than my chuck. I heated it up with a blowlamp until the shellac melted and covered the surface of the aluminium with it. Then whilst it was hot and molten, pressed the brass sheet onto the surface. I applied additional heat to the brass to make sure I had squeezed the air out. Then I let it cool. When cold I put it into the lathe chuck.
This is what the shellac looks like. This is called "Brown, button shellac". Brown because there are several grades and colours of it, depending upon what part of the world it comes from, and "Button" because when it is processed it gets stamped with a brand and looks like a button. It is used all over the world in foodstuffs, cosmetics and decorations including confectionery.
You can see from this picture that I was going to give the wax chuck a real workout, making this piece of brass plate into a round object. In fact if you look closely, the brass plate didn't quite cover the whole surface of the chuck. Indeed you can see the brown shellac just peeping out on the edge.
Well this is before and after. A nasty interrupted cut. It never even budged.
Conclusion ! A useful way of machining those, difficult to machine in any other way, parts.
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