You can also get glass makers' pliers to help breaking them in a controlled way
Before research labs could afford their own knife makers they used these  for
both ultramicrotome type glass knives and Ralph knives, but I can't give you
any more information than that I got some from EMScope at the time (20+ years
ago!) Incidentally you would use these to break conventional thick glass as
used for making ultramicrotome knives, the technique should be described in
some of the older textbooks, especially on electron microscopy.
Margaret Blount
Unilever Research
Beds
UK
-----Original Message-----
From:	Alan Bright [SMTP:Bright@dial.pipex.com]
Sent:	Wednesday, July 07, 1999 8:55 AM
To:	Histonet (E-mail); 'microscopy@sparc5.microscopy.com'; Tindall, Randy D.
Subject:	Re: Ralph knives

Hi Randy,

I hope this helps.

I used & made this type of Ralf Knife around 20 years ago.

1. Start off with a 3 X 1 inch slide and diamond score using a small set
square at the desired position.

2. Place a wood toothpick on the opposite side of your score line offset
from the line by say 2mm, this distance is critical and may need to be made
larger or smaller depending on the profile you achieve. Take care and wear
leather gloves and protective goggles, carefully press down on the slide
and you should have your Ralf Knife.

3. To use the knife on a microtome, I placed a standard steel knife in the
holder with a piece of sheet metal under the steel knife to act as a ledge
to support the Ralf Knife. Make your Ralf Knife  a few mm. longer than the
distance from the edge of the knife to the ledge at the base of the knife.

4. To fix the Ralf Knife  onto the front face of the knife, paraffin wax
was used by slightly heating both knife and Ralf Knife, and then waiting to
both cooled down.

I hope this information is of assistance to you, please say if you need
anymore information.


Best Regards.

Alan Bright

Bright Instrument Co. Ltd.
St Margarets Way
Huntingdon
PE18 6EB
England

e-mail: AlanBright@brightinstruments.com
Tel: +44 (0) 1480 454528
Fax:+44 (0) 1480 456031
www.brightinstruments.com
++++++++++++++++++++++++++++++++++++++++++++++++++++++=
-----Original Message-----
From: Tindall, Randy D. <TindallR@missouri.edu>
To: 'microscopy@sparc5.microscopy.com' <microscopy@Sparc5.Microscopy.Com>
Date: Wednesday, July 07, 1999 12:37
Subject: Ralph knives


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>
>Hi,
>
>I'm trying to get some information for a client who wants to try making his
>own glass Ralph (histo) knives.  He says he heard something about a
>technique for breaking these by hand, without the special knifemaker.  Does
>anyone out there in list-land know anything about this?
>
>Thanks much.
>
>Randy Tindall
>Electron Microscope Specialist
>Electron Microscope Core Facility
>University of Missouri
>Columbia, MO  65211
>
>