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Andrea Weissenseel
03-28-2010, 8:57 AM
Hi all,

how do you engrave small/thin items in rotary attachment, i.e. sticks with a diameter of 25mm - is it possible at all ?

My problem is, that the items are too low in the rotary to get it focussed because that "box" on the left side of the rotary is too high and in the way :confused:

Cheers, Andrea

Niklas Bjornestal
03-28-2010, 1:56 PM
You can try to extend the item. It might be possible to tape or glue something to the ends of the item so that the distance between the rotary and the item is big enough so that the laser head wont hit it while engraving.

Viktor Voroncov
03-28-2010, 2:49 PM
Niklas is true, we have set of plastic tubes (few different diameters). The lenght of tube is maximum distance between two rotary support. So if we want engrave small items, we just put it on plastic tube, insert tube inside rotary and ....

Gary Hair
03-28-2010, 3:01 PM
Andrea,
I engraved around a ring last week using a piece of dowel drilled to the size of the shaft that the cone-shaped piece mounts to. I cut slits in it with a bandsaw and used a pipe clamp to make sure it was secure. The ring was fastened to the end of the dowel with clay, sprayed with Cermark and lasered. It worked really well. For small items like that you don't need support on both ends, but it must be centered.

Gary

Mark Winlund
03-28-2010, 4:49 PM
Small is OK, here is a toothpick.

Mark

Chuck Stone
03-28-2010, 6:57 PM
I had someone make me two 'dead centers' that fit on the shafts that
hold the cup and the back plate. With these, I can use the rotary just
like a lathe. The centers hold the item about 3-4 inches away from the
box. The centers are made of stainless, so even if I laser the pattern past
the end of the tubes (I make pen blanks) it doesn't hurt anything.
(don't know how well you can see it in the photo)

I had to ditch the starting position, though. I'm not sure why they would
design the software so that the head can crash into the box, but they
did. So my rotary actually sits on the back ruler (on the left) and I have
the position marked on the table for repeatability. But I never start the
machine with the box in the way .. just in case.

One thing to note on that rotary attachment .. the 'tail stock' clamping
arrangement isn't very good. So I taped down the handle and never use
it at all. Instead, I'll loosen the rubber foot beneath the handle to move
the tail stock and then tighten the foot again. You want that good and
tight, otherwise you can lose drive.

Darren Null
03-28-2010, 8:00 PM
I use spacers for things like shot glasses. The cdr file is in this thread:
http://www.sawmillcreek.org/showthread.php?t=80713
"darren's custom rotary device thingy.cdr"
...and attached is what one looks like assembled. It works OK. If I built them again, I'd make one end of the "thingy" the same size as the rubber pad at each end for easier centering.

Hilton Lister
03-29-2010, 1:35 AM
I have actually taken the box off my attachment to give a little more clearance as I quite often tilt the whole unit to do tapered glasses. I just jack it up either end with blocks of wood as required. Crude, but effective.

Andrea Weissenseel
03-29-2010, 2:00 AM
thanks for all the answers

When I was trying to engrave a ring, I made me an extension to put it in between the rotary, that part worked - but what happened was that I almost shreddered the laser because I used autofocus and the table moved to far up, to get that small thing in focus, that the box of rotary pushed against the rail where the head is mounted - so Hilton's idea to take of the box sounds good.

Yesterday I saw that GCC now has two other fixtures for smaller items to use with the rotary, maybe that's an option too - but I don't think they solve the clearance problem.

Thanks, Andrea