(ATM) Ceramic tool update

[kferguson@aquilagroup.com]

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

P.S.  Thanks to those of you who have sent words of encouragement & support.