Solution to flashback

[David Arana]

I believe I have a found a solution to the whole laser/flashback/acrylic chipping problem.

I was trying to make keychains and had horrid results with the honeycomb table.

First step I took a piece of black granite that I had ruined. Flipped it over on the dull side (Dull side absorbs laser energy.) And I vectored on it to see where my keychains were being cut out.

Then I took some trophy ferrules and hot glued them onto the board.


http://i148.photobucket.com/albums/s39/Bardman2007/ferrules.jpg


Second step I did my cuts and here is the results!

http://i148.photobucket.com/albums/s39/Bardman2007/templating.jpg



This is the front side of the keychain. Witch I rastered first.


http://i148.photobucket.com/albums/s39/Bardman2007/key1.jpg

And this is the second side. I basically flipped it over, rastered and vectored.

http://i148.photobucket.com/albums/s39/Bardman2007/key2.jpg



And it worked awesome!!

[Dave Lock]

That s a really cool idea.

Thanks for sharing.

[Bill Jermyn]

I've done a similar thing.

1. Cover the table with paper (taped down, of course).
2. Vector circles in the paper where I want the ferrules.
3. Apply a bit of masking tape on top of the holes
4. Vector again, leaving circles of masking tape stuck to the table marking where the ferrules need to go.
5. Place the ferrules on the circles of masking tape.

I haven't needed to glue the ferrules, I just adjust the placement of the ferrules after every sheet is removed if needed, but they could be glued to the tape if necessary, I suppose.

[Garrett Nors]

Awesome alternative to pin tables!! Thane for sharing!

[Dan Hintz]

Another (quicker?) method is to design your layout in Corel with the posts in mind. Once your layout is finished, sprinkle some circles the size of your posts where the scrap will be (put these on a separate layer). Turn everything off but the post layer and laser... glue at those points.

[Bill Cunningham]

Another thing that works well. If you have some of the aluminum 1/2" fire grid/grate (A a quicky cheap cutting grid) stand a bunch of golf tees in the 1/2" grid squares and just set your acrylic on the golf tee points..

[David Fairfield]

That looks ideal for batch work, thanks for the demo! I will use that sometime.

For odd pieces, I've had some success in adjusting the power for the minimum to cut through the material. So the material absorbs most of the energy, very little to reflect back.

Dave

[David Fairfield]

Suggestion, and maybe you have a reason why you didn't do this, but you can speed your cut time and sometimes maybe squeeze a couple more parts on a sheet by merging together the long edges of the parts.

Dave

[James Jaragosky]

Suggestion, and maybe you have a reason why you didn't do this, but you can speed your cut time and sometimes maybe squeeze a couple more parts on a sheet by merging together the long edges of the parts.

Dave
When my new laser gets here next month I plan on power coating the grid table to prevent flashback.

[Michael Hunter]

When my new laser gets here next month I plan on power coating the grid table to prevent flashback.

But James - powder coat isn't laser proof!

It will be interesting to see how you get on, but I suspect that you will be swapping flashback for paint residue on the back of your work.

[James Jaragosky]

But James - powder coat isn't laser proof!

It will be interesting to see how you get on, but I suspect that you will be swapping flashback for paint residue on the back of your work.

It may not be laser proof but it is very durable. I have tried to vector text into some powder-coated discs with very limited successes. I am not sure on the coating transfer issue, time will tell.
I will keep you posted.

[Richard Rumancik]

Just a comment - "powder coat" does not actually specify a particular chemistry - just as "paint" is very generic. There are quite a few types of powders used in industry eg polyesters, epoxies, and mixtures, and different temperature characteristics.

I have successfully rastered off powder coat from a piece of metal to expose the underlying plating - but I really don't know what type of powder coat it actually was. I suspect maybe a polyester as it came clean with no charring. Epoxy might resist removal, but I can't say for sure.

[James Jaragosky]

Just a comment - "powder coat" does not actually specify a particular chemistry - just as "paint" is very generic. There are quite a few types of powders used in industry eg polyesters, epoxies, and mixtures, and different temperature characteristics.

I have successfully rastered off powder coat from a piece of metal to expose the underlying plating - but I really don't know what type of powder coat it actually was. I suspect maybe a polyester as it came clean with no charring. Epoxy might resist removal, but I can't say for sure.
Thanks for that clarification. The stuff I worked with was epoxy based.

[Andy Joe]

wow that sure was alot of work. I have a honeycomb vacume table, im guessing you get flashback off the metal right? All i did to counter that is take some packing foam and line two layers of it ontop of the honey comb, i then took a pencil and puntured some holes into it to get the air flowing a little better, next i set my product ontop of the foam and run my laser, no nicks in the back at all and the foam is disposible and takes about 2 mins to get ready to run. Maybe it will work for you?

[Dan Hintz]

Andy,

One problem I see with your method is that unless the laser cuts all of the way through the foam, the air cannot be sucked through the substrate, and thereby reduce the amount of smoke damage on the top. That said, I'm sure there are plenty of circumstances where that would be an acceptable trade-off.

[Mike Mackenzie]

FYI,

The big laser companies 500 Watts and up use old wet cloth towels to stop flash back and flaming when cutting acrylic. When they are used up they dispose of them.

[Sean Bullock]

I am looking at replacing the old aluminum honeycomb grid for my Speedy 300. The grid frame is in very good condition. Has anyone considered replacing the honeycomb with chicken wire? Any thoughts on how well it would work?

[Mike Null]

Sean

That and the rabbit cage stuff are very difficult to maintain a level surface.

[Bill Cunningham]

You can replace it with aluminum fire grid. It's .5 x .5 squares and comes in 2' x 4' pieces which can be sawn to size.