Re: (ATM) Ceramic tool update

[jbmcmath@intellinet.com (bruce mcmath)]

>
>I got my tool back from the ceramic shop last night.  No explosions or 
>breakage!  What a neat process: You give them a grey dirt clod, and they 
>return a white rock!
>
>There was some slight warpage (<1/16" concavity)  I have no idea how this was 
>supported in kiln, ceramic shop had 3 other customers waiting, and was trying 
>to get ready to close.
>
>I restored planarity (Is that a word?) with sanding....sure was a LOT easier 
>before firing!   
>
>BTW:  I flat sanded the back also, and had a lot of trouble with paper 
>loading with ceramic dust.  The grooves in the front prevented this 
>loading...lends support to  claims that grooves in face of tool speed 
>grinding, Thanks for that tip.
>
>
>Things I wish I had done differently:
>
>1)Make grooves after clay is dry.  It's easy, and clay is likely to crack 
>along grooves while drying.
>
>2)Try to make the disk dry from center out (??? maybe wrap saran wrap around 
>edges..)..This might prevent formation of crack in center. (Theory: edges 
>dry/shrink, and make middle expand in thickness..middle dries, but cannot 
>shrink radially due to hard edges and void (fault) forms in center)..but this 
>might just cause a crack to form in edge instead of center.
>
>3) Be even more careful to prevent "wedge"...I like the idea of rolling clay 
>between two guides to uniform thickness, then using a "cookie cutter" 
>(actually, a dull knife would do fine, I think)
>
>4) Make shallower grooves, I think I got carried away , 1/4" deep looks too 
>deep,  process also permits deeper grooves at edges (to accomidate curve) if 
>desired.         
>
>5) Ask Kiln Keeper if they can place on floor of kiln to reduce warpage. 
>
>So I now have a tool which I am pretty sure will work...(I can half fill 
>grooves, and crack with epoxy, and shim tool level on plywood backing) 
>Unfortunatly, I also believe I know how to make a better one...so of course I 
>am not satisfied.  I am thinking I will make another pass at this, as a biz 
>trip will delay start of grinding anyway.
>
>For the record: I have only about two hours actual labor in this tool so far. 
>This does not count time spent scratching head, writing posts about it, or 
>admiring results, of course!
>
>-Clear skies-
>
>Kevin Ferguson
>Astir CS "1U" (sailplane)
>KO0B

What do you preceive the advantage of all this to be?  You can make a dental
plaster and floor tile tool in less than two hours work and have no need for
third party assistance or the apparent hazards described above?

Bruce