Jig to engraving spheres

[Paul Proffitt]

Has anyone set up a jig to engrave spheres using the rotary tool on an Epilog? I'm working on it and have a plan in mind, but am curious as to whether anyone else already has something that works.

I have to engrave five wooden spheres ranging from 4" d to 1.25" d and will only be engarving around the 'equator', not all over the sphere. The engraving will not be continuous around the circumference, but there will be something on two opposing 'sides' of the equator. The opposing sides would not have to be engraved in one pass. I will be engraving some corporate logos. Most are from original vector art, one is from a JPG. There will also be some text and there will be one photo.

Any thoughts or suggestions are welcomed. I will be happy to post my solution as soon as I try it out to see if it works.

Paul Proffitt
Epilog 24TT 45 Watt, Corel 12 and Illustrator CS

[Frank Corker]

Paul, this is an interesting one, spheres are sort of the dread of all laser engravers I think. If it were me, I would consider something on the lines of using a cardboard tube, like the ones that you get posters/calendars delivered in. Cut it in the middle and use rubberised glue that can easily be removed later. Glue or attach one on either side of the sphere but be able to hold the weight between the rollers on the rotary.

[Mitchell Andrus]

3" diameter dowels and double stick tape jump to mind.

[Jody Malinich]

You will have to use something the same size as the sphere if you use a dowell type contraption. Anything smaller and the rotation will be off.

[Mitchell Andrus]

Jody... good catch.

[Gary Hair]

Originally Posted by Frank Corker

Paul, this is an interesting one, spheres are sort of the dread of all laser engravers I think. If it were me, I would consider something on the lines of using a cardboard tube, like the ones that you get posters/calendars delivered in. Cut it in the middle and use rubberised glue that can easily be removed later. Glue or attach one on either side of the sphere but be able to hold the weight between the rollers on the rotary.

How about PVC pipe instead of cardboard? It will be much stronger and less likely to flex. Cut it to length and use some self-stick foam or rubber to give you something to grip the spheres.

Gary

[Mike Hood]

A length of PVC matching about half the diameter of the sphere would be a great way to hold them in place while engraving them.

[Shaddy Dedmore]

Depending on the diameter, how about a square or a circle (or any shape) cut out of a 1/4" piece of material, acrylic, MDF... You just have to make the hole small enough so the sphere doesn't bottom out. To get away with a larger hole, stack/glue multiple layers.

Shaddy

[Dave Jones]

You can compensate for the diameter of the dowel or tube by cutting a pair of discs of the same diameter as the sphere and glueing them to the outer end of the dowels or tubes. The discs then ride on the rollers of the rotary attachment.

[Keith Outten]

Whatever style jig that is used will have to be aligned on both ends of the sphere perfectly or the sphere when rotated will wobble up and down. I would suggest a V-Trough be made to install the end pieces. Providing the sphere is three inches in diameter and the ends are the same the V-Trough should do the trick.

.

[Mike Hood]

Cut two MDF disks that match the diameter of your rotary fixture heads and mount the pvc to that on dead center. They'll center easily and shouldn't wobble to any huge degree.

[Paul Proffitt]

I very much appreciate all the replies. Obviously a lot of experience in this forum. My intended approach, which is about to be tested, is to use PVC pipe couplings and adapters. The PVC pipe and adapters are relatively inexpensive, relatively accurate with respect to dimensional repeatability and stability and the adapters are made to fit into each other.

I measured the drive wheel diameter including the o-ring as 2.62". A 2" PVC coupler is 2.728" od - same on all three I bought. By factoring in this difference in diameter if needed (see separate rotary tool post question) I can eliminate that difference as an issue. Then I can use some combination of a 2" to 1" adapter, a 1" to 1/2" adapter and a piece of 1/2" PVC pipe to handle the 4" to 1.25" diameter spheres. I would absolutely need to account for any difference between the diameter of the driven cylinder (the 2" PVC coupling) and the sphere and adjust my drawing's Y measurement accordingly.

I'm planning to align the two ends by chucking the two 'jigs' in scroll chucks on my lathe - one on the headstock and one on the tailstock. If the headstock and tailstock are properly aligned then the jigs should be aligned once the entire object is placed on the rotary tool. More later on how I plan to hold the jigs on the object to be engraved. I'll be exploring double sided tape as well as small strips of inner tube stretched from one end to the other.

More after I actually try it.

[Mike Hood]

I think I'm describing the Pinnacle / Laserpro rotary engravers. They can engrave pretty much anything you can clamp into them.

I'm guess this is more about the roller-type attachments?

[Paul Proffitt]

Yes, this is about the roller type (referred to by Epilog as the rotary attachment) tool.

[Mark Koenig]

Originally Posted by Paul Proffitt

More after I actually try it.

Well, how did it turn out???