After some fun getting my Mirror Matic machine built I've fired it up for the first time in anger. A few small problems cropped up. The intermediate shaft slipped in the bearings and dropped enough to cause the pulley to grate on the motor housing. Very loud way to find this out.
         After using waterproof tape to tape the 8" blank to the hat, I found out that it wasn't, when I tipped the platter upside down to clean the sludge. The blank missed the concrete gutter by an inch! After settling the old heart down after this, I bought a different brand of waterproof tape. That solved that problem. As well, I have decided to stop tipping it upside down without holding on to the bugger first!
         I made an edge on tile tool 80% size of the blank with the tiles spiral wound on. After a few wets some of the edge tiles started to come off. I found this didn't happen when the grit was gently shaken onto the blank, but, if a large amount spilled on there was a hell of a jump by the tool with occasionally a tile coming loose. I removed the outer layer of tiles but unfortunately the 2nd inner layer has started doing the same thing. I'm not too bothered as this is a learning experience.
         One thing I have noticed is that the hogging is a bit slower than I would have thought. I suspect that the tool is slightly big and also that there is a build-up of sludge under the tool which is affecting this. The next tool I'll make will be about a 60 to 65% size and I'll see what difference this makes. I'll be trying as well a different way of laying the tiles in the dental stone. I've noticed the much smoother centre compared to the outer areas of the blank. I'm using 80 grit with a turntable speed of 72rpm and an eccentric speed of 21rpm. There is around 1/4" of overhang with a wag of around 1/2". I think that the sludge is getting caught in the centre and grinding it to a smoother figure. Also, I'll reduce the weight that I'm using to see if this helps dig the centre a bit more. I'm currently using about 6 kilos on the overarm. Using more water seems to settle the grinding down a bit better, but I find that the 80 grit needs replenishing about every thirty seconds or so.  

This is a view beneath the turntable showing the three dogs I've screwed onto the platter. When it's taken off for clening the platter will sit level on the bench. 

This is a view of the tile tool I made. A slightly different design will be made for the next tool as the edge tiles started to come loose.  

Same thing as the other except looking directly down on the tool before pouring the dental stone. 

A test fit of the arm into the base of the tool. It fits nicely and works very well.  

All set for casting. assembly.  

Let the mess commence!! I realise I mixed with a scope in the background. Got a bit dusty!!