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Phil Salvati
07-16-2008, 11:39 AM
Hello all!


I am about to purchase a rotary unit. Judging by the way it was explained to me, the material for engraving should be a straight cylinder.

I have been getting a good bit of interest in engraved cattle horns, see picture below. Many have asked if we can make the design go around the horn. Horns rarely grow straight!

Has anyone tried to engrave material that wasn't straight?http://www.redearthdsigns.com/Cow_Horn.jpg

Dee Gallo
07-16-2008, 11:56 AM
Nice work, Phil!

I have a rotary unit from Epilog and it adjusts for tapering objects. I don't know how it would do if the horn is real twisty, you would probably have to make something to hold it so it rotates around one point.

What I really want to know is how you got your picture in there - did you just paste it in your post? It doesn't look/act like the usual posted picture.

cheers, dee

Darren Null
07-16-2008, 12:01 PM
You can rotary engrave stuff that isn't straight...but you have to burn on a bit that is straight *enough*.

For the horn showed above, I would suggest that a lens with a longer focal length (and therefore depth of field) would be a better investment than a rotary. You could then burn with the horn lying flat.

With a rotary, you have to keep the surface you're engraving on at a constant-ish distance from the laser. Horns aren't circular in cross-section, so the surface would be moving up and down (in and out of focus) with respect to the laser. Also, finding a good axis to turn the horn around would be quite tricky. Again, you could help yourself with a longer focal-length lens.

If you're going to try to burn right round the horn, then you'll need a rotary, but you're almost certainly going to need a long focal-length lens. If you are going to burn it flat on the table, you can probably do that with the kit you have...but again a longer lens will help you get a little way round the corners.

Phil Salvati
07-16-2008, 12:26 PM
Thanks for the tips!

Dee,

To add pictures... I have a blind page on my website that is not visible to visitors. If you right click on the picture you can see the address in the properties tab. Highlight it and put it in your browser.

Anyway.... I post pictures there for instances like this.... after it's published, right click on the pic, go to properties, and copy the addy. When you click on the add image tab in the reply screen, just paste the addy.... There ya have it!:)

You can't appreciate the engravings in this picture, but this is what one of the finished projects looks like.

http://www.redearthdsigns.com/Horse_HornRack2.jpg

Phil

Craig Hogarth
07-16-2008, 12:59 PM
Phil, take the pointy end, stick it in a thick piece of styrofoam and put it in the rotary. The whole thing doesn't need to be straight, only the engraving area. With a little playing around, you should be able to find the right placement. The rotary does allow you to rotate it before engraving, so while it's not a straightforward setup, it is possible.

Dee Gallo
07-16-2008, 1:27 PM
Thanks for the picture posting info, Phil. I don't have a blind page on my website (that I know of...) , I'll have to ask my webmaster about that.

The finished product you make is wonderful - I have found most people really like silhouettes and yours are full of life. Great job!

cheers, dee

Phil Salvati
07-16-2008, 3:04 PM
Thanks Craig! I'll give it a shot!

Dee,

If you have someone update your site for you than my way won't work for you without costing some money. Instead of using your own site, find a free picture hosting site, there are many, I just can't come up with the names off hand. then follow the same directions.

Phil

Doug Griffith
07-16-2008, 3:40 PM
Dee,
It's not really a blind page but an image in the root (public_html) directory of his website.

Have your webmaster create a subdirectory and give you FTP access to it. Or, ideally, set up an admin function so you can upload images to it with the click of the mouse.

Rodne Gold
07-16-2008, 3:51 PM
I wouldnt buy a rotary or try to fiddle with one to get circumferal engraving. I would use Darrens suggestion of a long focus lens and try do it in sections
What will help is a tray filled with playdough or plasticine to "clock up" the areas you are going to engrave to be a "flat" with respect to the beam as possible.
If you insist on the rotary way , then attaching 2 tins , like small tuna tins , filled with plasticine at each end of the rotary should make it simpler for holding the horn and would make it easy to shift when clocking it up.
Use something dangling from the head that will allow you to see if the thing is centred , ie dangle the string to or wire or what ever and let it just be slightly above the piece , rotate the piece and look at the gap. Way too fiddly imho.
I'm sure one or other laser mnfgr does offer continually variable Z axis sensing , this is something that is not that difficult to implement.
Imagine the utility of a laser that could follow contours............

Rodne Gold
07-16-2008, 3:52 PM
fotopic.net is quite good , 250 mb free , been around for donkeys years
www.fotopic.net (http://www.fotopic.net)

David Fairfield
07-16-2008, 5:49 PM
Based on my experience with the Epilog rotary tool, you would get very poor results with a cattle horn, due to the lack of symmetry. Even if you tried to prop up the pointy end in a foam disk etc.

The tool is designed for cylinders and tapered cylinders. Any tendency for the workpiece to wobble will distort the engraving.

Dave

Craig Hogarth
07-16-2008, 9:22 PM
Based on my experience with the Epilog rotary tool, you would get very poor results with a cattle horn, due to the lack of symmetry. Even if you tried to prop up the pointy end in a foam disk etc.

The tool is designed for cylinders and tapered cylinders. Any tendency for the workpiece to wobble will distort the engraving.

Dave

There's several advantages and disadvantages when comparing the epilog rotary to the uls rotary but in this scenario, the ULS wins out. An object doesn't have to be perfectly symmetrical in the ULS, as long as you can get it to fit in there and you can get the engravable area to stay somewhat within the focal point, it's doable. I've eaten those words on more than one occasion, but for the most part, I'm successful more often than not.

David Fairfield
07-17-2008, 9:24 AM
There's several advantages and disadvantages when comparing the epilog rotary to the uls rotary but in this scenario, the ULS wins out. An object doesn't have to be perfectly symmetrical in the ULS, as long as you can get it to fit in there and you can get the engravable area to stay somewhat within the focal point, it's doable. I've eaten those words on more than one occasion, but for the most part, I'm successful more often than not.


I don't have any experience with the ULS but I don't doubt you. I extensively used an Epilog rotary for engraving glassware, as company premiums and wedding gifts. I found it to be "less than optimal" due to wobble, and I'm reluctant to take these jobs now.

The engineering behind the Epilog rotary seems very smart, but it assumes workpieces will be symmetrical. After dealing with thousands of glasses from perhaps a dozen manufactuers, its pretty obvious that most glasses are not truly symmetrical. The more precise and complicated the design (the strong point of laser engraving) the worse the distortion caused by even minor wobble.

I have corrected for most wobble using weights in various configurations and adjusting the tool position, but the time consuming startup testing and the inevitable rejects all eat into profits, which are slim to begin with. Some glasses are just unworkable no matter what, which is a real problem after 100 are ordered, and 10 are ruined. What to do with them? Not to mention the stress and frustration, plus negative business issues associated with unreliablity of the machinery. I cannot take customer's glassware to engrave, for example.

I'm a big fan of the Epilog laser, I'm very pleased with mine, but I think Epilog should look seriously at a redesign of their rotary tool. I think a lathe type headstock clamp is optimal for gripping cylindrical objects, the design has been proven over the centuries by machinsts. Simply adding the option to screw on a commercial lathe headstock would be a major improvement over Epilog's current design IMHO.

Dave

Phil Salvati
07-17-2008, 10:06 AM
Thanks for all the tips! You can always count on the creek to get ya out of a bind!

It's been a while since I have seen the rotary for the ULS.... I don't remember if it was a squeeze mechanism (top and bottom). But David's idea for a lathe clamp would be great.

The main reason for the rotary purchase is a large run of custom duck call barrels, with a logo on each side. The barrels are slightly tapered, but it should work if I break the logos apart in segments.

Craig Hogarth
07-17-2008, 1:16 PM
Phil, the item gets clamped in securely with the uls rotary. Once you get it in there, it isn't going to move. My biggest beef with them is that it is designed pretty much for glasses. One end is concave, the other convex, making it impossible to do a "stick" without some ingenuity. I did some paintball gun barrels a while back and had to use styrofoam on both ends to get it to stay. The customer wanted engraving from end to end, which would be possible with the epilog but not with the uls.

As for the taper, you can prop the rotary up on one end giving you a flat surface to engrave on. The biggest issue is the engraving gets scewed if the taper is dramatic. But if it's a consistent taper, the envelope tool on corel helps to correct that.