[meteorite-list] Flat Laps

From: Bill Mason III <bmason3_at_meteoritecentral.com>
Date: Fri Dec 23 16:23:52 2005
Message-ID: <20051223212344.7C5118D67D_at_mailwash5.pair.com>

Dear Meteorite friends,
        I have been using flat laps for making telescope optics for over 50
years. So I will share some hard earned knowledge. May things have changed
in the last 10 years that will make your life simpler? I used to use cast
iron laps from 12 to 36" diameter. Each very heavy to assure long term ware
surface and stability. I used silicon Carbide as an abrasive with water. My
grinding rig was made of several gear boxes (1939 Chevrolet steering
gear)and a Thor washing machine (1936)gear box. My grinding base turned
around 6 times per minute - while a recipical device about 36" away turned
at 22 times per minute. With an arm from the side held the specimen being
ground in place the reciprocating arm guaranteed that the entire surface of
the lap ground evenly assuring that all would remain flat. I placed lead
weights over the arms and the specimen to add pressure downward.

        The biggest problems were the mess and the possible grit
contamination. I would use the following grit sizes: 80,180, 250, 400, 600,
1000. and then move to a pitch and pine tare lap with aluminum oxide, and
finishing with jewelers rough. I cleaned everything I touched with
detergent and water and I did it outside or I had special water grit traps
made. DO NOT USE YOUR HOUSE DRAIN as it will soon be clogged(UGH!)

        NOW I can share my present methods. I bought a diamond impregnated
magnetic lap cover from Diamond Pacific. They have 12" 18" 24" I have a
different grit 60,80,120,220,400,600,1200,3000. I use water mixed with a
special non-rusting solution M-435 10:1 And yes you have to use a lot of
water to assure both your meteorite and your hands are CLEAN, CLEAN, clean.

        When you finish one grade remove it and put the next diamond
magnetic blanket on to the lap.

        I then dry and etch, neutralize and dry again and then coat with my
own VCI-286 clear.

        Bill Mason "rusty" bmason3_at_comcast.net




-----Original Message-----
From: meteorite-list-bounces_at_meteoritecentral.com
[mailto:meteorite-list-bounces_at_meteoritecentral.com] On Behalf Of McCartney
Taylor
Sent: Thursday, December 22, 2005 5:04 PM
To: meteorite-list_at_meteoritecentral.com
Subject: [meteorite-list] Flat Laps

The time has come for me to buy a flat Lap for polishing slices.
Who can recommend a tried and true Flap lap and what size?

-mt

-- McCartneyTaylor, IMCA 2760
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Received on Fri 23 Dec 2005 04:23:43 PM PST