engraving graduations

[sbmathias]

I'd like to engrave some additional graduations around the compound on my lathe. Original equipment only has 45 degrees each way, and I often need to rotate it further.

Any suggestions on how to best do this? I plan on using a rotary table on a milling machine, but have several more specific questions:

1. Shall I just use a sharp toolbit, and use my table feed to force the toolbit through the material like a shaper, or buy a small Dremel-like engraving cutter?

2. How can I make reasonable numbers? No CNC, so need to stamp or somehow engrave numbers every 10 degrees next to the marks.

Any suggestions from anyone are appreciated.

[Joel]

At the risk of not answering the question asked, I solved this problem by placing 4 marks on my crosslide so I could use the compound graduations at any location convinent.

[SGW]

Joel, that's ENTIRELY too practical a solution! (Translation: I wish I'd thought of it!)

sbmathias, your #1 idea will work fine. You want something like a threading tool, only to a sharp point and maybe a 30 degree included angle. You don't need an engraving cutter. You DO need to center the work to "fine limits," as a couple thou variation in depth of cut will indeed be noticable, if you are aiming for fine, precise lines.

As for numbering: A set of number stamps will work. A set of 0-9 isn't terribly expensive. There's a natural tendency to think you need larger numbers than you actually do, so measure the height of the graduation numbers you're trying to more or less match before you buy the stamps. The real trick is aligning the numbers so they don't look cockeyed. A little time spend making an simple alignment fixture to hold a punch at a set height up from a reference edge may be worth the effort.

[sbmathias]

Thanks for both replies. I may use them both.

I have actually already put additional marks on my compound, but they weren't done deeply enough to be readily usable. Maybe while I have it apart, I'll work on them as well.

[Paul Alciatore]

I re-marked the handwheels for my Unimat a few months ago: the original lines and numbers were very poor and hard to read. Used a sharp "V" pointed tool as described above. I cut it from a broken drill, about 1/8" diameter if I recall properly. And yes, it's surprising how easily you can see a difference of a few thousanths in penetration. This tool was held in a locked vertical spindle and a dividing attachment was mounted on the mill table. The vertical feed determined the depth of the lines and the manually operated cross feed did the actual cutting.

The handwheels were small so for the numbers I used a 1/16" stamp set (American made) and an improvised jig to help align them. Just a block of oak with a 90* notch for the handwheel to rest in and a piece of aluminum clamped above to align the stamps against.

One thing I did notice was that the various numbers in the stamp set were NOT correctly centered - not even uniformly positioned. If I had just used the aluminum rest and nothing else, the numbers would have been positioned very uneven. I have two other sizes of number stamps (one American and one import) and they also were uneven. It seems to be a common problem.

I made a series of tests and determined the differences from one number to the next and used appropriate shims along with the stamps. I cut the shims from a "throw away" aluminum frozen dinner tray which was about 0.005" thick. Note that "6" and "9" are made with the same stamp turned upside down but with different shims.

I bought a small bottle of dark blue auto touchup paint to fill in the lines and numbers and it worked quite well. Wiped off the excess with card stock soaked with a little paint solvent. Finished it off with a light sanding with 600 then 2000 grit wet/dry papers.

One other thing I did was to orient the numbers on the three handwheels to be read from the front operating position. The carriage cross feed numbers are parallel to the axis and the longitudal feed and tailstock numbers are perpendicular to their axies.

Now they are a joy to use and read. (And Thrud, they are nice and shinney.)

[SGW]

Good point, Paul, about the numbers not being uniformly positioned on the stamps. My own set has very noticiable variations, and it needs to be allowed for.