Saturday, March 17, 2012

The evolution of a moto-tool stand

Long ago I made a stand for my "Moto-tool" device. These were originally made by the Dremel Company, but nowadays there is a horde of imitations, asiatic and otherwise. Giving credit where credit is due we will call it a Dremel-type tool, or DTT. Dremel offers a huge number of accesories for this tool, and more are available elsewhere. But a DTT is made for hand-holding, and I often find this extremely inconvenient. Especially when I am grinding. So I made a stand for my DTT, which is nothing particularly noteworthy.
Just some scrap wood with a hole big enough to take the DTT. This has given me great service. Drilling the holes to acommodate the DTT is the problem. It can be done with a hole bit if you have one, or with an adjustable circle cutter, which is how I did it. The rear hole is split and held in with a bolt and nut. This is part one of the saga.

Part two was when I made the NanoX table. (It is now the NanoY table.) I did this mostly for the experience, and it's in my posts somewhere. But it moves on one axis. So we have a problem, because it is very difficult to put it just where you want it. Especially for grinding edges on my microforged tools.

Part three when I tried to make a milling vise for the Taig lathe milling attachment. This was a failure. The reason was that the holes were drilled imprecisely. When you are doing metal, you have to work to at least 0.1mm. In wood, 1-2mm will get you by. Another universe, as they say. Can't do it by eye. But I looked at it and thought that if I remade one piece it might work, not as a vise, but as a cross-table for an X-Y table. This is milling machine-speak. A mill is a bit like a drill press with a table on which you put the work. The work is shaped by a rotating cutter. The table can move left and right (X) and back and forth (Y). Milling machines also can move vertically and this, obviously, is Z. Sooo...
Here is the beginning of the thing. At the top, the NanoX table (which has become NanoY now) that I made last year. Below it is the new NanoX table. It has two pieces of square bar, in which a couple of pieces of hardware-store rod about 5mm fit. This came out of the failed Taig milling vise. The white plastic block is a piece of snow machine, found while I walk. I know not its original purpose, but it is some sort of synthetic and very easy to machine, so I drilled holes to fit the rods and tapped the center hole for the feed screw. The NanoY fits right on top of (new) NanoX:
And behold, I have both X and Y movements at the turn of a screw. The real problem in this megilla was scribing the centerline of of the square bar at left. I finally figured it out. I put the thing into the milling attachment of the Taig lathe. This gadget essentially turns the Taig lathe into a mill: X, Y and Z all there. I chucked a scriber in the lathe. With a magnifying glass I registered the scriber at the very bottom of the square bar. The Taig milling attachment has a handwheel that will give you "thous" i.e .001" or .025mm if you wish. Measure your bar with digital calipers. Calculate how many full turns + thou it will take you to get to the halfway point. Hint: 20 turns per inch. So one turn gets you .05". Horrible, I am reduced to RGU. I don't mind it too much. All decimals. It is the fractions to which (not to end a sentence with a preposition) I object.
You do that with the vertical (Z) feed on the Taig. Then with the Y feed (the cross-slide in the lathe incarnation) just draw the scriber across the bar. You have coated the bar with machinist's blue, maybe, but I use a sharpie felt-tip pen. Machinist's blue is hard to find in Alaska. You have a centerline as exact as you can get it. You are limited by the very marginal travel of the Taig cross-slide. Hey, it's a watchmaker's lathe. Don't be too harsh on it. It was made to cut stuff 1cm across. You are demanding 5cm from it. Tough on you. It is a fact of life. No matter what lathe you buy, it will be too small. But it worked. The X-Y feed table, bar a few details, is a done deal.

In machinist-speak, what I did was lay out holes by the coordinate method. Any time you think high school algebra was a waste of time, think of that. In these days of Computer Numerical Control, or CNC, it is even more important that you understand coordinates. If your avocation is poetry, you have no need of them. If you want to make things, then do brush up on coordinate geometry.

And now I have figured out (I think) a feed in Z. I will have made the DTT into a micro-mill. But I haven't done it yet. So I am holding my breath, and my posting, at this point. Stay, as they say, tuned.

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