Alignment / Jigs on Oval Material

[Terry Swift]

What do you use when lasering on ovals - a jig or something else? I ask as so many materials vary in sizing from a couple of hundredths of an inch upwards and if you build a jig, then what happens when you have that different size shape. No such problem really exists outside of ovals, as they don't necessarily align properly if not using some type of jig. I guess it's the nature of the beast, like in woodworking - measure twice (or more) and cut once; but ovals are an odd lot.

[Tim Bateson]

For what I believe you are asking, I usually put blue tape on the raster table, laser an outline on low power. Perfect placement every time.

If however you need to do a lot of them, then do the same on thin MDF board, maybe even rastering a shallow area to place the object.

[James Terry]

I've been experimenting this month doing double sided keychains. This requires a flip of the substrate while maintaining registration. I finally came up with a good method for me. Simply, etch side 1, cut a centered box around side one, flip the box to side 2 while securing the main substrate to maintain registration, etch side 2 then contour cut. This can give very minimal waste. I can squeeze 10 units on a single 14" panel.

Corel allows you do have multiple pages for a file, and when you are setting it up, you can copy your art and paste to page 2 and it puts it in the exact same spot, so you know they are lined up. Sometimes I'll mirror the image or whatnot depending on the contour cut.

You can see the process here (http://www.youtube.com/watch?v=2f2X9TXF_bE) done with a bamboo panel from Colorado Heirloom. I have since figured out my contour cutting issue seen here...

[Hilton Lister]

I use scrap cardboard for all sorts of shapes. just vector the outline at low power and position the article that way.

[Rodne Gold]

An oval should align if you cut out a rectangle the width and height of it out of some substrate and place the oval in it

[Frank Corker]

Hilton's suggestion is as good as any. Use cardboard stacked on top of each, starting with a smallish hole, getting bigger with each successive layer, until the oval shape at the midpoint has been achieved.

A really useful product for making templates and very easy to cut, is laminate floor underlay, which I'm sure you guys will be able to buy at your local Lowes. It can be bought for only a couple of quid and cuts very acurately, is soft enough not to scratch or damage whatever it is that you are working on. It's made up of reused cardboard and over here it is green in colour and green in nature.

[Terry Swift]

I think Rodne's idea is good; as I've been using some cheap fiberboard paneling to cut a multi-item jig; as I've got quite a few orders for some oval granite pieces. I guess my problem in making this work for me is that I've been measuring the length and width and creating an oval template 2-3 hundredths larger to accommodate the piece(s). Since the granite ovals are not the "exact" same size per every piece - then trying to make a single jig for 4 of them to use over and over doesn't work. While the MDF is not all that expensive when buying it in 4' x 8' sheets; maybe the tape / cardboard idea would work and be less expensive (so many bright minds in this group to come up with creative ideas for it all). As my digital caliper only goes to 6.08"; some guestimation on length comes into play - even if we're talking hundredths (as I score the backside and measure point to point - then add). Also each piece is not exactly oval - so the square method probably will work best. I also use the cut-out pieces from the MDF to test my computer drawings as I have found that some tweaking in CorelDraw is necessary since C & E doesn't always put the piece in the center location - so WYSIWYG is out about 2% of the time. For the keychain - yes using the cut-out as your template makes the most sense when flipping (nice video too).

I'll continue to play with all these ideas as at $7 a pop + shipping / handling; screwing up many granite tiles becomes an expensive lesson in both cost and futility.