View Full Version : Sugestions to do flip op on 2 sided wooden coin

Michael Kowalczyk
06-21-2006, 12:23 AM
has anyone perfected a system to do 2 sided coin type work? I am doing a 750 to 1000 pc run of a 2" circle with 1/8" hole at top for keychain. Front and back have bitmap to engrave an vectors to mark and cut. There are 55 on a 12 x 24 sheet. Right now we are cutting one side all the way and then holding down the waste and flipping them over and then very carefully trying to align them. then we run the back side that has not vector cuts, just engrave and mark.

I was thinking of marking the perimeter and the keychain hole center on a piece of 1/4" MDF, then find a hinge screw that just fits in the 1/8" keychain hole and line them up this way. Takes a little more set up but I think it will be faster in the long run. plus I can use it for other projects that require a 2" circle flip op.
Another thought is to use the same MDF as the bottom but then use one of the cut out sheets from the front side and then glue it down to the MDF. The only problem is that even though the laser kerf is minimal/hairline, you can still have enough play to be off center.

I appreciate any thoughts or ideas.


Shaddy Dedmore
06-21-2006, 2:10 AM
With that many, it seems like it might be worth it to work with the registration and raster one side, filp, then raster and vector. Would save a lot of flipping time :)

hmmm, an idea just popped into my head to combat the problem, but I'm not sure it'll work (works perfectly in my head though). Set up keychains to be symmetrical about an axis, I'll choose horizontal, based on the picture I have in my head of your project. Set all the objects to be equal distances apart, and aligned to a grid. Then make a rectangle that is cropped evenly around them all, with the group of objects perfectly centered within. Then, when you raster one side, vector the rectangle. Then flip the whole thing (bottom then becomes top to keep the holes of the keychain aligned on the right side). Then raster all the stuff on back (180 since it's upside down now), then vector the shapes.

here's a visual (it's not aligned/centered like I said to do, it was just a quick visual) If you lined everything up right, flipping the whole vectored rectangle over should keep all the keychains in the same spot. There might be a slight offset do to the laser kerf being off to one side of the cut line as opposed to centered on the cut line, but it should be consistant enough for you to compensate with trial and error.

Might consentrate on flipping right-to-left if your project is different.

If it works we can call it the Kowalczyk maneuver :)


Joe Pelonio
06-21-2006, 9:38 AM

Someone may have a better way, but what I have been doing is the same
as you have done, but when rastoring I add marks to the waste piece that line up with something on the image to allow for better placement when flipping. Also on the artwork, if possible, I try to avoid anything being right on the edge so alignment is not as critical. I use a small hunk of duct tape to remove the pieces for flipping, and have the waste piece masking taped
onto the vector grid rulers so it can't move.

For a key chain, though, a simple bump-out around the hole would allow for perfect registration every time.

Carla Lange
06-21-2006, 10:13 AM
Sorry, I can't visualize this process, but my suggestion would be to raster and vector cut the front side, but leave a little when you're vector cutting. Then when you flip the whole board, you just raster that side and finish the cut so they fall out. Is there something I'm missing?

Carla Lange

Rodne Gold
06-21-2006, 11:41 AM
I would vector cut them all first and then make an acrylic jig where an indentation of the coin is engraved away and the hole left standing proud, drop the coins in and engrave front and back with perfect registration when you flip em.

Joe Pelonio
06-21-2006, 12:06 PM
Sorry, I can't visualize this process, but my suggestion would be to raster and vector cut the front side, but leave a little when you're vector cutting. Then when you flip the whole board, you just raster that side and finish the cut so they fall out. Is there something I'm missing?

Carla Lange
Carla, that only works if the pieces are perfectly aligned within the material, and each piece of material is cut exactly perfectly because even a small difference in the saw cut would throw it off. You have a good suggestion if the run included cutting out a perfect rectangle arount the group of key chains so that it would always be perfectly aligned when flipped, but that would take a lot more time.

Michael Wells
06-21-2006, 1:05 PM
Here is how I do it. I set up the artwork in CorelDraw with four layers. One for the vector cut for the items, one for a vector cut of a box around the entire work, one for the front raster, and the last for the back raster. The outside vector box has to be perfectly equidistant around the cutouts and they need to be equidistan from each other vertically and horizontally. You can do this quickly in Corel too.

Lay layers exactly over one another and register them that way. Put you blank material in the laser, and cut only outside box on the first vector run. Now you have a perfectly square piece to work with that can be flipped with perfect registration.

then do your rastor on the back, flip, raster and final vector the front..voila, timesaver by adding a cut!

If you prefer to flip the individual pieces, you can use the same method, just cut out a jig to hold them, and since that is registered with a square edge, you can just vector cut them with the first side raster, then when they are all cut out, flip them and put them in the jig to raster the second side.
Hope that helps.

Michael Kowalczyk
06-21-2006, 2:05 PM
Thank you all for your quick responses.:) We are all pretty much on the same page with ideas but that is what makes this forum awesome. brainstorming like this. It may just be the way I was trained or my dislike of using the honeycomb grid for vector cutting wood but I am currently using the eggcarton plastic grids for ceiling panels so that the bottom does not get scorched from the laser being reflected back. It does keep the bottom cut clean. I have looked at the after market systems that hold the material suspended as an option but $350.00 + is a little too much for it. I do have a plan for a DIY one but that's another post. So doing a vector cut on the flip is really chancy if I am off a 1/16. I have also been told that as you get further away from say X0 Y0 that it will skew slightly. So with this thought if I try to flip 180 degrees what becomes X0Y0 was X24Y12, therefore it would start off with a +offset and be Ok in the middle but then a -offset at the bottom right corner. To make a long story short, Rodne is right on target:D. engraving the coin area first and leaving the keychain hole proud/untouched will solve the alignment factor. Michael's suggestion is also on target. I have them set up in 4 layers/colors so that I have the vector cut on the back to use only for the flip op template. I appreciate all of your input and others that I hope will continue to input after my post. this is something that I want to perfect as much as possible.

Joe's mention of a bump out is a great registration idea for other projects when they are symetrical. Most of the ones we do are 1 sided. I like those fast and easy but this one is a donation to praise and worship concert on Galveston (Stewart beach) this weekend (Sunday) so I do not have a lot of time to experiment on this one but have many ideas thanks to you all.

Thanks again,


Michael Kowalczyk
06-23-2006, 1:38 AM
Hello All,

Just keeping you posted. I am engraving a 16 x 24 sheet of 1/4" acrylic at 100% Power and 10%Velocity, that will have 77- 2" circle key chains recessed in the acrylic about .060 to .075 and will have the keyhole untouched to serve as a registration post. It will take a long time to finish:( but will be useful on the next project also and will definitely make rastering the back side much faster and almost full proof. It is running right now as I am typing and half way through the first row of 11, it was at the 10 minute mark on our digital stop watch. So I guesstimate it will be about 2+ hours for the whole sheet of 7 rows. I may make a 2nd one, if time permits, so I can run it like a shuttle. When one is running we can be loading the 2nd sheet ready to reload the laser.
I ran a single sample to test the mold and it was snug yet easy to postion and remove. I then ran the back side raster and the registration was right on:).

I will post a few pictures later.

thanks again for sharing,


PS we have a Trotec Speedy II with a 60 watt laser at 140 IPS so our setting may be different than yours.

PPS- Boy does time fly when your having fun on the forum. Just looked at the stopwatch and it is already at 51 minutes. That's one of the many benefits of the laser when doing long jobs. You can do more than 2 things at the same time

Shaddy Dedmore
06-23-2006, 2:08 AM
I'd like to make one more plea for the raster - flip - raster/vector method. Especially after hearing Michael Wells does it that way.

I think you may have misunderstood (easy to do the way I ramble).


If you align correctly, you can flip it. And you wouldn't flip AND rotate, you would only flip it. In my new example, X0 Y0 would become X24 Y0 (not X24 Y12). Notice the red lines (well, you only need to look at the verticle one) and how the right half is a mirror image of the left half.

If you etched the first side, cut the rectangle, then flipped it (so the right side becomes the left, but the top is still the top) it should be aligned to then raster then vector all the shapes. You can arrange the shapes differently, you just have to make sure that the right half is a mirror image of the left, and that the rectangle is centered around the shapes.

I think with the amount that you have to do, it might be worth trying to figure out.


Rodne Gold
06-23-2006, 3:08 AM
Michael , there would be a far quicker way to make the jig than raster engrave , take a sheet of 3mm pex and vector engrave the big circles outline and then vector CUT the small holes
Use anjother piece of 2-3mm and cut the circles right out , samwich the 2 using the vector engraved circles as a registration template and glue. Use wooden doweling to stick into the holes you cut in the lower panel that will locate the coins small hole (you might not even have to use a dowel , you could probably easily line up by eye if you have precut your wood blanks)

George M. Perzel
06-23-2006, 3:49 PM
Hi All;
Shaddy's method is quick, accurate, and will work fine- provided you can cut all the material the same size and the layout drawing is accurately positioned so that the left and right margins are exactly the same-doesn't matter what they are just so they are equal.