When using a 'scope, centering your work accurately on the revolving axis.


~ Elite 1000 Member ~
Nov 19, 2006
Mendocino. ca., and Scotland
Where engravers make use of a microscope, rather than head visor, there have been some posts on the subject of keeping your working area always within view of the 'scope, and better still, to be able to move the workpiece so that some particular scroll or other element is lined up directly on the revolving axis of either the ball vise, or if this is disabled and instead a turn table used upon which to stand the vise, then to center the element directly over the revolving axis of the turntable.

Turntables are sometimes supplied with a metal bar, to use as a target, if a rigid scope is to be set with field of view concentric with the work axis, but in high magnification this is sometimes less than satisfactory.

For those who might be struggling a little with this situation, I propose describing an inexpensive and practical way to quickly center the smallest elements on the revolving axis. Reference should be made to the photographs which are a mixture of the general to the specific details.

The idea is to mount an inexpensive pointing laser in a high position allowing the beam to point down on the workpiece, while keeping out of the way of the engraver, and also to be able to identify the revolving axis without much trouble. So first the revolving axis is found, without having to interfere with the work already in the ball vise, after that, the laser beam is centered on this axis, then any small area of the work may be quickly pulled accurately to the axis for convenient working.

I make no excuse for my laser fixture looking a bit hastily made from a piece of firewood. It does the job, and sometime soon I will remake it to look pretty.

Discussing for a moment the 'scope mount, you will see mine is of a simple and rigid design, as compared with some mounts that look like an overheard crane, quite bulky, and a bit wobbly. However many engravers work on a variety of jobs, some quite large where my scope stand would not be suitable. My workpieces are not very large, so I prefer a simple and rigid mount, but one that allows the scope to be swung aside and work continued using a visor if preferred , yet retain the laser unmoved. You may chose a better mount for your situation.

My scrap wood laser holder allows the laser to both tilt and swing, hence it can be made to point anywhere one chooses.

Anyone considering using a laser in this manner would be quite disturbed to see how bright and splashy the red spot is, and be tempted to discard the whole idea. So no use proceeding unless the cheap laser can be tamed and reduced in intensity and 'splash'. Fortunately this is easy to do by reducing its input voltage.

There are so many inexpensive red lasers of the "one milliwatt" low power variety, that is is a bit difficult to choose one. Some years ago I had to pay $250 for the same device, but now they are cheap and ubiquitous. So best just get one for about $4 at your local hardware store, like the one that comes on the end of a ball point pen and may also have an LED light. I like the ones that have a adjustable focusing lens that can somewhat narrow the beam, but another way to narrow the beam is to stick an almost black or overexposed film negative over the laser front and pierce the film with a thin needle.

Now to tame the high intensity of the beam, as it is irritating and not necessary for our purpose. Take out the three small batteries that together deliver about 5 volts D C, then saw off most of the laser body to leave only the business end ..... the last inch or so. Remember, almost always, the outside body is the positive polarity, and the central spring is the negative. What is needed is a 110 ac voltage supply that will convert to around 6 volts DC ... we don't want to be bothering with batteries. Fortunately, discarded AC adapters are everywhere these days, as they power many small devices, I have a box full of discarded ones, but if you don't, some place like Radio Shack will sell you one, and while you are there, you should spend about $3 on a variable potentiometer and a few feet on very light insulated copper wire. A potentiometer is sometimes called a 'pot', and is used for the likes of volume controls on small radios, etc. Choose one that can handle a few watts of waste heat, not the very tiny ones!

With reference to the photo of the circuitry, I suggest to wire the system on the bench as a trial, and satisfy yourself that it works, by turning the Pot knob, it should go from no light to full brightness, but do not go full bright, you only need a modest red dot shining on your work. If you get it working as a mock-up, it might encourage you to then make the wood holder with its tilting laser mount. Don't forget to glue that piece of aluminum or copper between the pot and the wood to act as a heat sink, and while you have the glue in your hand, you could glue the "on" button to be permanently on, as the pot knob will turn the laser off. But even with the laser off, there will always be some current going through the pot, hence a heat sink to keep its temperature below lukewarm.

You may have to customize the wood mount to suit your set up?

Let us assume you have now got a laser shining a modest red dot on your workpiece, and your mount will allow the dot to be set anywhere. You want to set it on the revolving axis, so it will then be a useful reference destination.

Now turn your attention to the photos, that show the long brass arm attached to my bench, it can swing out to the workpiece with its little pencil on the end. I arrange for mine to come to a steady stop, but not exactly to the center of rotation, a little bit off, so when I press the pencil down onto the work ( or onto a white label temporarily stuck onto the work), when your turntable is revolved, the pencil scribes a small circle, the center of which is the revolving axis. Swing that brass rod back out of the way, and now move your laser dot to be shining in the center of the circle, pull off the label, and you may work on, with the advantage of pulling your work area accurately to axis center in a second or two. You can use the pot knob to disappear the dot or bring it into view.

This took probably longer to describe, than to actually make!

In summary, seasoned engravers can quite legitimately yawn and pass on this, having worked for a life time quite happily eyeballing the situation. I have. But now that I threw this together for fun, I kinda like it.

I appear to have not mastered the new system of putting my photos in the right order, maybe some one to explain how this is done?



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