Tips

Marking Sandpaper Sheets for Identification

When sanding small objects, I think most of us probably use the technique of cutting/tearing a sheet of sandpaper into quarters and then folding those sheets into thirds. I use Norton 3X sandpaper and, before I started using this technique, once the sheets were quartered and folded into thirds I often had difficulty identifying the grits since above 150 they’re all on the same color paper. In addition, the grit is only printed in one or two places on each full sheet, so it’s often not on the back of a quarter sheet.

The way I get around this is to color code the various grits. 150 is red, so it’s not a problem. For 220, 320 and 400 I use red, blue and green respectively to identify them. My method is pretty simple. When I remove the sheets from the box, I use a sharpie of the appropriate color and make two lines down the length of the paper and in what will be about the middle of the quarter sheets. It’s not important that the lines are neat, but it is important that they run from edge to edge. That way when the quarter sheets are folded into thirds the line appears on each third.

It doesn’t take much pressure to make the lines so don’t press to hard. Use light pressure and the sharpie will last a long time. Press too hard and it’s quickly ruined.

The lines remain vivid throughout the life of the paper and I’ve never had the colors transfer to a piece I’m sanding. No more hunting for the grit on the back of the paper. No more rubbing the paper and trying to decide if it’s old 320 or relatively new 400.

Powermatic Remote Switch Problems

Not long after I purchased my remote switch from Powermatic, it quit working. The paddle arm would move, but the lathe would not turn on. I first tried calling Powermatic and the tech was very helpful. He offered to send me another switch. When it arrived, I discovered that he had sent two switches which were appreciated. Unfortunately, while otherwise almost identical, they were standard type lever switches and therefore weren’t as convenient as the paddle design of the original.

With the new switch operational, I felt comfortable in tearing apart the original one. What I discovered is that they are fairly easy to disassemble and all that was required was to remove the shaving that had worked their way into the contacts. After installing the now clean original in the switch box, I placed a medium-sized sandwich bag over the top part of the switch box and used a large rubber band to hold it in place. The sandwich bag cover almost eliminates the need to clean the switch although it needs to be replaced occasionally due to wear.

Below are a few images of the original switch to give you an idea of what to expect if you need to clean yours.

Powermatic lathe switch assembled The clips that can be seen at each end hold the base to the switch. Use a screwdriver to hold them back so that the base can be removed.

Powermatic 3520 A amd B lathe switch assembled

Here’s a side view with the base removed. The shavings can be seen filling the plastic cover over the pins.

Side view of 3520 A and B switch with the base removed

Here’s the base and switch together

Side view with the base removed

Powermatic lathe switch closeup of lower section base from the top and bottom. The two rockers in the base are the heart of the switch. The two pins are shown in the side view above slide over the rockers as can be seen from the wear streaks on the rockers in this photo. That movement is what makes and breaks the electrical contact. Shavings somehow get into this area and either get between the contacts or otherwise keep the rockers from making contact.

switch closeup of lower section base from bottom
switch closeup of lower section base from the top

Here’s a close-up of the top and bottom of the rockers.

Close-up of the top and bottom of the rockers

Here’s a photo of the switch specifications should you wish to replace it. It is a J-9301A with two sets of specs: 20-12A-125/250VAC and 19-12A-125/250VAC

Switch specifications: J-9301A with two sets of specs: 20-12A-125/250VAC and 19-12A-125/250VAC
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