Wednesday, June 1, 2011

A Bubble Level

I've had this little bubble level sitting in a drawer for years. I must have gotten it from an old colour laser printer that was being scrapped. I've finally thought of a use for it, but I'll want it to have a round base. 'Time to remove it from that steel rectangle and make it a proper base.

A 7/16" plate washer will serve for a base.

The screws are M2x6mm, and I don't have an M2 threading tap. I'll see if I can fake it with a bit of interference fit trickery and CA adhesive.

A proper machinist might sneer at some of my methods, but I find masking tape to be invaluable as a layout aid. Here's the washer covered in masking tape with the three hole locations transferred to it with a sharp pencil.

My close-up vision is not what it used to be, and a layout done on masking tape is helpful to me because of the tape's 'impressibility'. With points spotted on masking tape, I can make small impressions in the tape at those points with an awl point while viewing the work under an illuminated magnifier. Those impressions in the tape then give me a tactile way to confirm that I'm locating the point of a centre punch correctly.

Here's the washer having just been drilled with quite remarkable accuracy.

Those holes were drilled with a No. 49 drill. I'll explain how I arrived at that size of drill.

Miking the screws gave me their diameter as 0.075". A No. 49 drill is 0.073" diameter. There's my interference fit. I'll be forcefully installing the screws in holes that are 0.002" undersize.

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And here's the completed level.

That more-or-less worked. I would like to have had slightly longer screws -- one of the three screws stripped instead of gripping; the screws only had a couple of threads worth of engagement. The other two went in ok. I applied CA adhesive to the ends of the screws from the underside of the washer so it could wick in around the screws.

I think I can call that a success. For what little is being asked of those screws, my interference fit w/CA adhesive added is quite adequate. Now I can get my wife's miniature birdbath installed with its bowl level. (I did mention early on that I had thought of a use for this thing. Here it is. Scroll way down.)

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