Mill CNC - Engraving?

[Wanna-Be]

I don't have CNC on my mill but have a question for those who do.

I just completed refurbishing/saving a Gorton 3U PantoGraph/Duplicator. I don't mind that it is all manual because I'm not doing much more than engraving dials/drums for some of my old machines (old machines fixing old machines). I got this Pantograph really cheap but it came with out any master copy for engraving. There are plenty available but cost several hundred per set.

It has been suggested that if I had access to a CNC mill I could have a Master Set milled on a plate and then I could duplicate each individual character on multiple Copy plates.

My question: Are most CNCs capable of doing this task, say, in a batch mode. Where the plate stock is set up and the program will mill each of the entire set, one after another, from begin to end?? Or does a machine operator have to rest the tool for the each character??

I know a fellow with a CNC mill and he loves to show it off. If it as single operation I would ask him to do this sometime when his mill is "not doing anything". And I'll provide the stock and the beer.

Just curious??

Steve

[FLSTEAM]

The answer is yes. The amount of work to set up each character is a lot and a lot of time changing out each master. Even more work when you take into account that most will need many of the same thing.

John B.

[GlennW]

It shouldn't take much setup at all to engrave a master plate.

Here is an example of a 6" x 6" master plate with 5/8" characters that would be held in a 6" vise, face milled to clean up one side, then flipped and face milled on the other side while supported in the vise with parallels to keep the two surfaces relatively parallel. Probably no thinner than 1/2". Program the characters for engraving and then just press the big green button and watch the machine do the work! If you wanted multiple fonts, you will need a plate for each font. Then, once you have the plate made, use your pantograph to cut one character on individual rectangular plates that would nest together to form words or whatever.

Pretty basic work for a CNC mill.

You could, of course, make individual plates for each character using the CNC mill by just swapping out the squares of stock in the vise, but it would take longer and need a bit more programming time. It all depends on how much "fun" your friend with the CNC mill wants to have!

The cutter shape and depth of cut used with the CNC mill for the master would be dependent on the shape of the stylus on the pantograph so that the stylus would smoothly and accurately follow the engraved character. Spindle speed, (or the lack of) on the CNC mill may be a factor as well

[Wanna-Be]

Thanks Glenn,
That sounds about like what I would expect. I just wasn't sure if there would be a pause for the operator to move the cutter to the next character position.

Yes, making the master is all I would want, since the time and effort for the CNC to individuals would be more that the manual time on a PantoGraph, working off the master copy.

The example illustration would seem to be a bit small for a master since the larger one goes, the better the quality the new copy plates would be. Normally on the PantoGraph, one would use a larger size master copy and engrave at 2:1 or greater for reasons of better results on the finished product plate. Also easier to trace the larger letters with the style.

I'm thinking get some 2"X1/4" or even 3/8" bar stock and machine both sides. Put half the font on either side. Length of bar would depend on table limitation of course. (Just thinking out loud again)

Thanks

Steve

[Harold_V]

If you are not familiar with the operation of a pantorgraph, it might pay for you to do some research before attempting to make sets of characters. For one, they must be made such that they install on the platen provided, and they must be of a given size if you hope to be able to use the original tooling that comes with the pantograph. Sets should include multiples of each character. so you can engrave without constantly stopping and relocating for each character.

I have very limited experience on those machines, but I have operated both a two dimensional and three dimensional model. Unless I'm mistaken, you won't be able to make characters of a size that is used by starting with one smaller. Pantographs typically do not scale up.

While I haven't taken a look in recent years, sets of characters used to come up on ebay occasionally. They generally sold for about $75, which would be a real bargain if they have not been used beyond their useful life. They are made of brass and wear such that it becomes difficult for the stylus to follow the pattern in areas where lines cross, such as the junction of the numbers 3,4, 8, or the letter b, T, X----you get the idea.

Harold

[GlennW]

The example illustration would seem to be a bit small for a master since the larger one goes, the better the quality the new copy plates would be. Normally on the PantoGraph, one would use a larger size master copy and engrave at 2:1 or greater for reasons of better results on the finished product plate. Also easier to trace the larger letters with the style.

My intended use of the plate image above was to use it as an example of what possibly could be quickly made on a CNC mill to be able to take it and then make your own individual copy sets of the correct size squares for your machine in whatever quantities you felt you would need. I have no idea what size the original individual copy plates would have been for your machine or what size characters would have been cut on them. The same for the width, depth, and profile of the characters cut into the individual plates.

My intention was to convey a concept, not a detailed finished example of what to have made.

I imagine it may also depend on the size text that you plan on engraving. I used to send out engraving, and now do my own, but none has ever been any taller than .125" characters, .005" or less in depth, and all in metal. To others, the though of "engraving" may bring to mind 6" tall 1/2" deep characters in wood signs.

[Wanna-Be]

Glenn, I didn't mean to come off critical. Just trying to make a point that the Master copy in a manual PantoGraph starts out at least twice the size of the end product engraved plate, for the sake of detail resolution. Similar to Hi Res pictures will reduce well but poor if enlarged.

I just picked up an Upper Case standard type on ebay for $28 plus $25 S&H (ouch!). Then I went back to count the number of brass font copys that are 2 11/16" X ~2" X 117ea = ~ 16 lb.. So, they maybe charging $5 for handling, I'll give them that.

To respond to Harolds reply and respected comments. At the moment I don't have a OEM platten tray for the fonts. I will most likely make my own since i want a universal copy table for duplicating odd patterns. I can make the slots of spacings to hold the non-Gorton fonts. The fonts I just got are Hermes as are others of interest. The Gorton font sets seem to go for several hundred while the Hermes around $30 to $70.

I am shooting for the larger size copy and I recognize that my machine can't enlarge, however can do 1:1 but the tracing Style has a limited travel range so only a few characters could be done at a time. I'm not sure what the max reduction is for the 3U but the scale goes from 2(&1) to 8 but when I had it set a 8 and did some trace tests the circle came out wierd and a straight line came our skewed as well. But that could have something to do with fine tuning the platen, etc..

Yes, there is a lot to be learned about this stuff. That's what I'm here for. If it was easy, it wouldn't be a challenge (fun).

I always appreciate ALL comments and sorry if I sound otherwise.

Thanks

Steve

[Bill Shields]

word to the wise that has not already been covered.

If you are doing it from brass, suggest you use ANNEALED brass, or as soon as you start cutting into the surface, these things can start buckling.