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In search of the magic pantograph engraving attachment for round material

cl5man

Aluminum
Joined
Sep 6, 2004
Location
AZ
I've been using a pantograph manual engraver with great success for several years. It a a New Hermes VB2. It's a fairly heavy duty machine, i would compare the fit, finish and smoothness to my Bridgeport. I've got everything I could possibly use with this machine but I still can't figure out how to engrave a barrel without using some form of rotary attachment. I've racked my brain for two nights now trying to figure it out and I've given up. I've attached a picture of how I do engraving on barrels currently. As you can see it takes some time to get the flat area made in the mill and then set up in the engraver so the flat is perfectly level. I've got number stamps but I'd like to make the barrel markings as informative as possible. Any advice on some homemade or manufactured attachments I could use? 1.jpg2.jpg
 
The only ones I know of (other than linked rotary devices) use a form plate above the spindle to control the cutting height as the spindle moves around. This requires a machine and spindle that are compatible with such a form plate, and it's definitely limited in the slope you can reasonably engrave.
 
I've been doing some experimentation with Mastercam for 4th axis machining. What you are describing is easily done on a cnc milling machine equipped with 4th axis machining. Probably way too expensive to acquire the machinery to do it, but you should be able to find a cnc shop in your area to do it for you.

Lord Byron
 
cl5man , I have the same engraver but I have not used it yet. Do you have the manual for this machine? There is an attachment that I believe allows the quill to float in the vertical axis. The attachment has a small lever that would require finger pressure to keep it in contact with the round surface. If you dont have a manual let me know I have a spare copy. I would love to see a closeup shot of your tool profile, this is the thing that has kept me from using mine
 
purchasing a full blown CNC engraver is out of the question. if i was to invest in a used CNC engraver i'll save up and purchase a used CNC mill that will kill two birds with one stone. But regardless of what id like to have im not in a position for that type of an investment at this time. Id really like to make what i have work and if i cant i'll just continue to do it the way ive been doing it. Im just trying to save some time during builds.

I do have a manual but i havent noticed any type of attachment listed in it. I'll look it over again this evening to double check.
 
Forgot the profile question. I use standard carbide engraver bits. Mostly use the .010 size tip but occasionally i'll go down to the .005 size tip. When i purchased the engraver i got a New Hermes engraver bit sharpener along with it. Ive got tons of newly sharpened bits in all sizes ranging from .005 all the way to .035.
 
I've got one of the Deckel accessories which does that - haven't used it yet, but it's a clever little set-up with various gears to match the cutter movement with the diameter of the stock. You can see one about half-way down here: http://www.practicalmachinist.com/v...ills/sale-ended-12-22-06-a-108754/index4.html
Those attachments do show up on ebay from time to time and I'm interested in owning one before too long... I think folks generally ask $500.00 for them. There might even be one listed now. I shall look and report back if there is.
 
Since it seems unlikely that you will find a suitable attachment at a reasonable price to fit your machine and do not wish to go CNC I think you will have to Jerry-rig something. I offer the following simply as a rough unproven concept. In order to engrave on a cylindrical surface all motion in the Y axis must be converted to rotary motion of equivalent surface travel to avoid distortion. I believe that complex linkages and gear trains would be impractical, especially as the diameter of the workpiece will vary.

Therefore what I suggest is based on the same principal of linear to rotary conversion that makes an antique wood turner's spring pole lathe function. A tightly tensioned belt wrapped one or more turns around the workpiece might work if the work was held between centers attached to a sliding carriage that tracked the spindle movement in the Y axis so that the center line of the work was always directly under the spindle. A crude illustration of the concept is shown below.

rotary panto.jpg

The ends of the belt are anchored to the machine table at a height tangent to the cylinder. As the carriage slides in either direction along the Y axis the cylinder should roll proportional to the Y movement of the spindle and sliding carriage.

The difficulty with this scheme would be attaching the sliding carriage to the spindle housing in a manner that would track movement in the Y axis precisely without constraining X axis movement of the spindle housing or the slight rotation needed in a pantograph.

A lathe top slide with the screw removed might serve as a basis for the sliding carriage.

It may well prove impractical but I thought that it was at least worth suggesting. Perhaps it might inspire a better method from either yourself or another PM forum member.
 
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With what you are doing a very simple CNC router with 4th axis might work, and could be very cheap.
Zenbot 1216 CNC Router

Having said that our department had an old pantograph that was sold off when they closed the machine shop. To this day I wish I had found a way to get that machine, they are so much more fascinating than a CNC.
 
This thread inspired me to get mine cleaned up and play with it. Here's a couple of pictures I just took. I think the stack of gears on the right are original to the machine while the stack on the left were shop-made. I'm going to make a center rest attachment to replace the tail stock for longer pieces, like rifle barrels.



 
This is no help. I don't have the funds for a 4th axis attachment so I bite the bullet and pay a company to engrave mine. The engraving I have done is .010 deep so ATF is happy. An engraver who does trophys can't get that depth on a piece of 416 S.S. It also shows up well when Cerakoted.
 
You can get that deep with a hand or impact graver like the Lindsay Airgraver no problem, but that's a another setup and another skill set. I had an Airgraver for a while and used it to sharpen the edges of serial numbers which had been buffed too hard.
 
New Hermes engravers operate differently than the deckel's. I had a new hermes and now have a gorton p1-2 which is very much like the deckel. The new hermes has a rub collar that surrounds the cutter and rides on the piece to set the depth. The gorton/deckel operates in a plane much like a milling machine and as was mentioned form tools can be installed above the spindle to make it follow a contour. The picture shown is of a device that converts the y movements of the deckel to cylindrical movement. This would not work on a new hermes engraver. I used to engrave on round surfaces by just keeping my letters small so the depth variation was not noticeable. It would seem like you could also buy an additional rub collar and modify it so it would do a better job of following a cylinder.
 
I am speaking in ignorance, but I would gather that the pressure of the spring can be adjusted for various materials, hard to soft. I'm sure trial and error would be required.
 
There are plenty of 3D pantograph engraving machines around,and most are not too expensive since they are really obsolete. In reality,they are really more like 3D light milling machines. They have small spindles that take normally single flute or flat sided cutters,and are run by long,round belts. It would probably be better to upgrade their spindles to air driven or electric high speed spindles.

They used these machines years ago to mill out rollers with fancy cookie shapes and all kinds of applications where a large master was made up and traced. These are fairly heavy machines,probably 1000#+ in weight.

I had a book(which vanished) about a guy who makes great miniature firearms with one. He even makes functioning miniature ammo for them. He traces from the real guns. His work is fantastic.
 
Well, very interesting. I'd be interested in seeing a video of it working on toolsteel. I wonder what control you'd have over the depth of the lettering.


I looked at their products (engraving cutters) and software for producing cutter paths for 2d and 3d work (mostly for cnc mills with 4th axis), and am convinced that what the OP wants to do with engraving machines to produce good results on cylindrical objects (rifle barrels) requires some pretty sophisticated machinery (cnc milling machine with 4th axis) and sophisticated software. Good luck with finding a seat-of-the pants solution. If you had the proper equipment, you would probably be in demand to provide these services. You probably could set up a Tormach to do this for about $20.000.

Lord Byron
 








 
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