Jig ideas for very round materials

[Harry Radaza]

I have a client who gives me good repeat business. However, its a PITA to accomplish. Most of his materials are wood. about 30mm in diameter. slightly concave in the bottom towards the middle. I have to engrave a border design around it. The border of course has to be about .5mm inside the outer edge.

The problem is.... these are all hand made and some are not accurately done. If my border engraving is off by a bit and not centered, then he rejects it.

The only way I can think of to make sure each material is centered properly is to have a piece of cardboard in the bottom, laser a guide on to it and "fit" the material centered on to the guide (taking into consideration any imperfections the material may have). So far so good. But this process is time consuming and a headache. Anyone have any ideas on how best to make a jig for this?

I am thinkging of making an MDF with cutouts but the slight imperfections of the material might give me lots of rejects. And I dont have some junk material just like his to test out.

[Mike Null]

Harry

If I ever had one of those days when I felt like I had enough customers the jig I would make would be one that would reject all imperfect blanks so I wouldn't waste time engraving them.

[Bruce Volden]

Mike's right!

How is it possible to maintain those spec's (.5 mm) when the items are not the same??

Bruce

[David Fairfield]

Yeah thats a quantity job I'd be very reluctant to take because its labor intensive and the probability of rejects is high.

I'd recommend to your customer that the wood part be supplied to you with a little extra material around the border, you laser it, then he finishes the outside edge to .5 of the engraving. He'll end up with a tidier product, too.

Dave

[martin g. boekers]

Don't you just love it when the client expects tighter tolerences than the product he provides!

[Doug Griffith]

My cat decided to pin me down this morning so I "had time" to draw something up.

I would create a fixture out of acrylic that wedged in the up left corner. It would have an acetate overlay with the design lightly etched onto it and a sliding insert that holds the part.

1) flip the acetate out of the way
2) insert the part into the "part holder"
3) flip acetate back over the part
4) visually adjust alignment by moving the "part holder"
5) flip the acetate out of the way
6) laser

Cheers

http://www.dogcollarlabor.com/IMAGES/sawmill/ROUND-PART-FIXTURE.gif

[George D Gabert]

Could you make several fixtures with different diameters. start with the smallest hole fixture. If the part does not fit in go to the next. When you have a full sheet laser it. and continue to sort and fill as required.

A different sorter could be made with slots of differing widths with sides on that you roll the parts down and they drop into the proper bucket to fit into your sized fixture.

GDG

[Craig Hogarth]

I had a similar problem a while back and came up with a solution that really helped cover my butt, although not sure if it's as feasible for you.

One of my customers acquired the original shale roofing tiles from the old Iolani Palace in Hawaii. He and his son do scrimshaw on it, wholesaling it to gift shops in Hawaii. He had me engrave a brief story of the palace and his family on the back to replace the stickers he was using. The tiles are all different funky shapes, so no jig was possible. The big problem was that my idea of center was way off of his idea of center, so I gave him 4 acrylic rectangles of different sizes with two holes cut out in the middle. He would center the desired sized acrylic on each piece and mark the two holes with a scribe. Using the holes, I was able to determine the proper size of engraving and proper placement. On ones he wasn't happy with, I was able to show him that it was alligned exactly as how he had instructed.

[George M. Perzel]

Hi Harry;
Do you have a "Center" start position in your laser driver?
Best regards;
George
LaserArts