Thursday, November 12, 2015

Oil stone vs. sandpaper



For sharpening forceps and spring scissors I use "translucent grade" Arkansas oil stone purchased from Dan's Whetstone Company, Inc.

My friend asked me which is finer, the oil stone or 2000 grit sand paper. Which is better for sharpening forceps and scissors?
So I compared them.

This is 2000 sandpaper with the tips of my favorite spring scissors.
The grain itself seems fine enough for sharpening, but the surface is not very smooth. Looks bumpy. It may be OK for sharpening a fine tip.
When I used it, however, I found it too soft to polish a sharp edge. The paper dents slightly and that blunts the edge. Just a paper, but it felt like a sponge at this scale. It's like sharpening a razor blade with a sheet of mud. The edges got chamfered, which is not good.

Now, this is the oil stone.
It looks like the stone surface is out of focus, but actually it's not.
It turned out that the surface of the extra-fine grade oil stone is smoother than 2000 sandpaper.
And much harder. This is important. The polishing material has to be solid hard to make a good sharp edge.

Thursday, November 5, 2015

Sutter P-97 SRAM battery outage



If you are here looking for "how to replace SRAM on Sutter P-97", just get a DS1243Y-120 from anywhere online. It is far cheaper than buying it from Sutter. 


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Well, I noticed that our electrode puller (Sutter P-97) had forgotten everything when I came back from SfN.  Not just those programs I put, it showed weird characters for time and date. I gave a suspicious inquiry to students whether they did something stupid. They did not, of course. It turned out that the battery for internal storage chip failed while no being used for a weak.

The Sutter company personnel told me that the battery on the internal memory chip had failed.  I needed to reinstall a new memory chip (SRAM CO-U688243-P97). The puller maker gave it a long name, but it is just a regular SRAM chip made by Dallas.  

On the mother board inside P-97, it says DS1243Y.

I looked up and found there are several subtypes: 
DALLAS DS1243Y
DALLAS DS1243Y-120
DALLAS DS1243Y-150

DS1243Y-120 is way cheaper than DS1243Y.
"120" means access time (120 nano sec). DS1243Y has 200 ns access time whereas DS1243Y-120 has 120 ns. Of course, the faster the better. I can get DS1243Y-120 online for ~$10 or less. DS1243Y is about $70-$75. The prices must be determined by supply, not specs.

I get a quote from Sutter and they said their DS1243Y costs $60 and $20 for shipping. It sounded reasonable. So I took it. I thought maybe it has to be DS1243Y. Maybe it cannot run with DS1243Y-120. 

Turned out, they sent me DS1243Y-120! Like I said, I could get it at 1/10 price from anywhere online. Don't get it from the puller maker. 

After removing 6 screws, the top cover can sit on the front panel like this. Avoid bumping the sensitive part under the solenoid cage. 

I bent some pins when pulling it out. Who cares.
Insert a small flat-head screwdriver into the slit at the front end. There is no opening to wedge on the side.


The memory test says "THE RAM IS BAD" probably because this is DS1243Y-120. But it works fine. Also, the programed date, day and month, still showing weird characters. Guess it's trying to look like made in Japan.