Engraving a degree scale

No -- you simply keep the engraving cutter too high to touch the workpiece, and draw lines using it as an indication. These are not precise marks --just enough to tell you to not cut there yet.

That works -- if you are using a rotary table and a dial on the hand crank. But if you are using an index head (which is what I would be using, and which has no dials) you can set the arms so you move from one arm to the next (perhaps with two or three full turns between arms if you are marking angles greater than what a single turn of the crank provides. In the case of my index head, which has a 40:1 worm, you get nine degrees per full turn, so for the ten degree steps you would need to go one full turn plus the distance marked by the arms, which select a certain number of holes on a circle of N holes. Once you reach the new position, you move the arms (which are locked together) so instead of the trailing arm touching the index pin, the leading arm touches it, so when you crank again, you again move to the trailing arm.

For the 5 degree and 1 degree motions, you will be less than a full turn, making things even simpler.

Hmm ... You don't need to set the arms for the 10 degree setting anyway when just marking -- you simply set for five degrees, mark the starting position as blue, then crank five degrees out, mark in red, crank again for blue and so on until you reach the starting point. Then you set stops to limit the travel, lower the cutter to make contact with the workpiece, and cut, then crank out two five degrees steps and cut again. Once that reaches its start, you crank out five more degrees, set the stops for the medium length lines, and cut, again going in ten degree increments until you have completed the circle. Then you reset the arms for one degree increments and the stops for the shortest line length, and crank and cut on any stopping place which is not already cut.

Then you wash off the paint with solvent and figure out how you are going to engrave or stamp the numbers for the long lines.

The index head reduces the chances of mis-reading the dials, but you need a special index plate to do things like 127 (for making metric transposing gears).

Enjoy, DoN.

O.K.

Not too much -- except that I might look for index plates and arms to fit the rotary table instead of depending on the dials. The rest I would do as I just described in the followup to a previous branch of this thread. (I'll plead laziness for not typing all of that again. :-)

But your way will work too -- just a bit greater chance of making an error in reading the dials.

Enjoy, DoN.

DoN,

In partial reply, I have index plates for the table, but it looked to me like something that was intended to be used in the vertical orientation (axis parallel to the mill table)??? The truth was I needed the table, recognized the potential value of an H/V, and the indexing setup was cheap enough that I bought it figuring I'd use it some day. I have not taken time to research exactly what I bought. I more or less get the idea of index plates and at least some of why you recommend them here. What is not clear is whether I can use them with the table horizontal, which I _think_ is the correct way to scribe the lines in question.

More dumb questions to come ;)

Thanks!

Bill

The most common use is in cutting gear teeth on an arbor between the table and a tailstock, but there is no reason why you can't use the plates and arms with the table in the horizontal orientation as well -- as long as it does not hit the table. And even then -- you could make a riser block to avoid this problem.

I *think* that your table may be a 90:1 ratio, so you get four degrees per rotation of the crank, and you can use any index plate which offers a circle of holes which is a multiple of four, and probably the smallest multiple of four would make the proper hole easier to hit. Anyway -- five degrees would be one and one quarter rotation, one degree would be 1/4 rotation, and ten degrees would be two and a half rotations.

If your worm gear ratio in the table is different, then these figures all change, of course.

You should be able to. And yes -- horizontal is the way to go if you are using a half-round Vee tool as suggested by someone else yesterday. But you have other ways to do it, too. One way would be with the edge of a dovetail cutter with the head tilted half the included angle, in which case you would use a vertical setup so you could move the cutter along one side of the plate which you are cutting

-- parallel to the center height.

In my case, I would be using a horizontal mill, and probably a conventional milling cutter with a sharp V to cut the lines --though I could come in from the side with the half-round Vee from above -- or from above with the vertical adaptor in place. In any case, I have bed stops with micrometer adjustment, and lever feed, so I can cut the shortest lines first, adjust one stop back an appropriate distance, cut the medium lines, and adjust it back again and cut the long lines.

Keep asking. Others learn as well when you ask, and answering the questions makes the process clearer in the minds of those who are answering.

Enjoy, DoN.