Sharpening Steel Needles

[sirkut]

What do you guys do to sharpen them?

[Guest]

I rub the front cutting face on a flat sharpening stone! Had some limited success...couldn't tell you the grit or even if it's a good idea.

[piaptk]

I know this topic is long dormant, but does anyone have any tips on sharpening these things? Possibly with a dremel tool?

As an aside, about how much cutting time do you guys normally get on a $90 sapphire needle?

[markrob]

Hi,

I've been making and sharpening stylii with a home built lapping setup based on a Inland Swap Top kit.

http://www.inlandlapidary.com/singleproduct.asp?search=Flat+Lap+Machines&partnum=10886

I use a 6" 1000 mesh diamond lap to rough the angles and then flip the lap over and use 14000 mesh diamond powder to polish to a mirror finish. To grind the angles I use a simple template laping method. Here's a link with some photos.

http://home.comcast.net/~markrob1066/site/?/page/Cutting_Stylii/

I've experimented with high speed steel drill blanks, tungsten carbide drill blanks, and .032" shapire rod mounted into a .062" aluminum shank. I get the best results with the steel blanks. The carbide seems to sharpen fine, but I don't get the low noise I would expect. Saphire is very britle and its easy to chip. When I get lucky, it works well. I'm still learning. I can re-sharpen quickly by just hitting the front face with the 14000 mesh powder on the lap. I'd be happry to answer any questions if this is not clear. I've been considering geting a used faceting machine, but they can get expensive. It doesn't take too many $90 commercial stylii to recoup the investment.

Mark

[mossboss]

Hey
You are right markrob Take a look at this it would not take that long at $90 a shot for sure
http://www.rockpeddler.com/pg13.htm
Seems to be at the better end for amature work due to non mechanical parts on the dividing head
I have tried to use mechanical head facetors with no success It seems that this may be a goer
Cheers

[markrob]

Hey
You are right markrob Take a look at this it would not take that long at $90 a shot for sure
http://www.rockpeddler.com/pg13.htm
Seems to be at the better end for amature work due to non mechanical parts on the dividing head
I have tried to use mechanical head facetors with no success It seems that this may be a goer
Cheers

The Graves seems to be the starter machine for people in the field. The price gets better if you consider used machines. These appear on ebay all the time. Some times in the $200-$400 range. My crude setup will not compare to one of these. Still not sure that a DIY setup can create the burnishing edges of 1 -5 um. But from some of my reading this may not be needed if you use a heated stylii.

Mark

[mossboss]

Hey, You are most likely right How about a small gear box from a high quality multi turn potentiometer They come up all the time as well
say a 30-50 to one ratio so as to drive the micrometer spindle on this gadget
It should get pretty close I would have thought Just a bit of food for thought
We have tried as well with no success We also had a pro diamond cutter having a go at them He used diamond powder on a thin copper plate as a lap with very fine olive oil as the carrier of the powder
No result there either I might add this exchange of ideas is two way I am learning a few things as well
Cheers

[markrob]

That is an interesting idea. Another thought would be to hack into one of the cheapy micrometers from china. I think that even if you could microposition the stylus in relation to the lap, you would have to contend with any runout in the lap. This could occur either from the bearings or the lap itself. I'd love to see how this is done, I suspect its a very specialized art.

Mark

[mossboss]

Hey Markrob
I do know that the Jap's first cut the saphires the nomal way after they establish the grain of the stone. They get the straight lines so as to form the cutting face obviously so as to provide the strength on the one hand on the other it is easier to cut So the burnishing sides are cut at an angle but across the grain which is also a bit easier while maintaining strength They are lapped first as normal However the finishing is done on the flat face of a lapping wheel along the perimeter rather than the face I was told the faces where slid across horizontally so as to get the accuracy necessary They where than bonded to the shank with some magic mixture of rare earth alloys which was done under vacuum with RF heating so as to melt the "glue" to bond the stone to the metal It was a slow process which is reflected on the cost of them
This was explained to me by an old cutter who was involved in stylii development back in the fifties. Worked together with the lady of Capps fame, with the micropoint's and all that wonderfull stuff I think the man has passed on now, if not he will be well into his nineties Good luck to him Lost touch He did have a couple of unique cutting stylii made in Japan by a famous Jewel maker as in watch Jewels he was to gift to the Sound and Music archive museum somewhere in the US Scratching the memory bank so as to recall where. It may come to me. Keep at it
Cheers