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Old 07-04-2008, 11:22 AM
airamp airamp is offline
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Join Date: Mar 2008
Location: Scottsdale, Az.
Posts: 683
Default Re: Sharpening the lindsay Point on a faceting machine

Hi Ardee,

Sharpening on a faceting machine is not hard at all.

First sign up and get the patent information on grinding the Lindsay parallel point. It is a education in itself..

Steve said I could give out this information on the forum for sharpening on a faceting machine so here it goes.

I will try to explain the 115 degree lp for you you should read the patent info. and related it to this information to get a good understanding of how these are ground and some of the principals of the parallel point and its modifications.

Your pin vise should be tight in the mast. Get a pin vise and turn down the shaft in a lathe or put it in a drill press and with a fine file get it to 1/4 inch so it is a nice fit in the mast. Once close use semichrome compound to polish it and get a nice fit.

Next put it in the mast but do not tighten it. Set up a lap on the machine and a machinest parallel (1/4 inch is nice) or a precision ground lathe bit. This keeps the vise with a blank above the lap so you can set your zero and tighten the vise in the mast and get your 0 on the loft guage.

set the index at 45 degrees (on a 96 it is #24). Now you have the pin vise, blank installed in the vise and tightened on the flat of the blank and the vise tightened in the mast. Rotate to 96 or (0). Your cutting point or top is indexed to 0.

First I grind the face at 45.

Set the mast at 45 degrees loft and index at 48 (180 degrees)and grind the face. (I use 260 diamond lap with coolent, then go to 600 and then to 1200 for now).

I then grind the top of the graver (I like this as in Steves discripton).

set the loft at 10 degrees and back to 96 index.
Grind the top facet (rotate the index to 12 clicks each side which is # 12 and # 84 (45 degrees from 0 each side) as you did the face (3 laps).

You now have a graver blank with a face and the top relief's done.

For grinding the cutting primary, secondary cutting you have to do a little math. A 96 index plate is 3.75 degrees a notch. You should have a Cheater on the machine to split this. So since the gravers are different numbers of degrees it depends on your cheater to get both sides accurate for the parallel point.

In faceting stone cutters use what is called meet point faceting. it is discribed in Steves patent as to getting the facets to match up one side to the other.. Your cheeter with be very very close but it is good to rough grind one side then the other and look at it closely to see that the facets match. Write down the numbers here and your cheater setting....

Ok so now:

Set the 0 now at 48 (0pposite the 96 Your new 0 for cutting your blank cutting edge)

REMEMBER THAT THE CHEATER WILL BE + OR - DEPENDING ON WHAT SIDE IS BEING GROUND... TO GET THE RIGHT ANGLES EACH SIDE. IN OTHER WORDS YOU ARE AT 0 PLUS OR MINUS DEPENDING ON YOUR CHEATER TO INCREASE OR DECREASE THE DEGREES TO GET WHAT YOU WANT (CLOCKWISE OR COUNTERCLOCKWISE). THIS IS THE HARDEST PART OF THIS EXERCISE...

For a 115 secondary angle go 7 1/4 (use your cheater) to 27.5 degrees for each side. Set the loft at 2 degrees. Rough grind your point. Check to be sure it is they are even. Change laps and grind them with 600, 1200, and 3000 with semichrome. (I usually do the face and tops also polished with 3000 and semichrome.)

Now for the heel or primary angle. Put on a fine lap 3000 with semichrome, add a cd to a master lap, corian,tin, copper what have you for making the parallel point cutting edge.

Set the loft at 15 degrees and index at 8 3/4(cheater) each side to get 32.5 degrees.

Do not power up the machine. put semichrome on the lap and lightly rub back and forth and check the facet often to be sure it is parallel. if not make your corrections with the cheater (very slight changes). Larger primary angles make a graver go straight and it doen't like to turn much. Smaller primary angles (heel) is for easier turning but it is harder to make a straight line. To decrease heel just grind the face a little.

You should have a perfect lindsay point in 115. Sound complex but if you are use to using a faceting machine this is very easy to make any angle you want with any releaf you want.

Now you have the sequence here are two more.

tops are the same.

120 is

secondary 7 clicks - 1/4 (cheater) @ 2 degrees loft for 25.2
primary is 8 clicks no cheater @ 15 degrees loft for 30

90 is:

secondary is 11 clicks -1/2 (cheater) @ 2 degrees loft for 39.2
Primary is 12 clicks no cheater @ 15 degrees loft for 45.

REMEMBER THAT WHEN YOU USE THE CHEATER ONE SIDE WILL BE PLUS AND THE OTHER SIDE WILL BE MINUS TO GET THE CORRECT NUMBER OF DEGREES FOR YOUR 0 (48) ON THE CUTTING SIDE OF THE GRAVER...

Once you get the hang of it you can make your own index plates for the grinds you use with a mill and a index and deviding table if you have one..

Of course Steves Sharpening system is the easiest. I am just a tool freak and love this kind of stuff.

Hope this helps you.

Regards,
Mike (airamp)
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