From: John Murray 
To: Amateur Telescope Makers 
Reply-To: John Murray 


One further thing is that this method works best when doing tile on edge
tools. The possibility of voids is much greater than the conventional tiles
laying flat layout. How tight you pack the tiles and the thickness of the
slurry both contribute to the # of voids in a tile on edge tool. This is
why the sander idea was developed.

Cheers

John Murray
Whyalla
South Australia
Check our web page at http://astronomy.sa86net.com ATM and M-O-M stuff.
Latest Ronchigrams only at http://www.users.bigpond.com/imasloth/


> -----Original Message-----
> From: owner-atm{at}shore.net [mailto:owner-atm{at}shore.net]On Behalf Of John
> Murray
> Sent: Friday, 15 August 2003 12:35 PM
> To: Russell Jocoy; bobmay{at}nethere.com; atm{at}shore.net
> Subject: RE: ATM Tile tool questions
>
>
>
> Russell,
>       I've been doing the agitation via orbital sander for a few
> tools now with
> no problem. I took the advice from the USG site before I started
> doing this.
> The photo and data sheet for Hydrocal 105 (which is what I am using) has
> under the heading "Pouring" the following advice.
>       To prevent air entrapment and provide a uniform smooth
> surface, careful
> pouring of the slurry is necessary. Agitation of the filled mould is a
> further step used to prevent air at or near the surface of the cast piece.
>
>       As I say, the orbital sander floats the air bubbles out and
> fills any voids
> easily without making a mess. If you get caught when the plaster starts to
> go off you can give yourself some more time to get it right. The thing
> though, is that after the pour is done and while the plaster is
> still fluid,
> a quick burst of the sander usually prevents you from getting
> caught out in
> the first place thus avoiding the need to do the agitation after it has
> started to go off.

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