Monday, June 16, 2014

How to Make Rubber Stamps with a Laser Engraver

It's been over a month since the last post, but that's for good reason. Besides getting sick, I have been working on new things, and this is one of them. I've invested a lot of time into figuring out a very good way to make high quality rubber stamps with a laser engraver.

Before you dig in, you're going to need to know something about engraving in rubber. It smells. It's truly one of the most awful smelling things I've done with a laser engraver. If you try this, get the fans going, open the windows, and maybe even wear a filter mask if you have one. If you don't have a filter mask you should probably at least wear a paper one, for safety, since the engraving process makes a lot of very fine white ash that is noxious and irritating, and you wouldn't want that in your lungs, throat, or nose. Having said that, you are responsible for your own health. Proceed at your own risk.

To start with, I am using special laser engraving rubber. It's supposedly low odor, but that's obviously some kind of cruel joke. That said, natural rubber and other synthetics like neoprene are far, far worse. I am also using a simple general-purpose spray-on adhesive and 3mm thick craft foam I found at the local crafting supply store.

Don't forget to horizontally mirror, or you'll be sorry. Like I was, the first couple times.
Begin by setting up your design on the computer. You will want to be doing your engraving in a raster mode, and you need to invert the design and horizontally mirror it. Make sure you have a border around your design so that there is enough room to trim the stamp later.

To get a good cut it is critical to do the following things:
1- Use as much power as you can. This engraving needs to be really deep, the deeper the better. With my 40watt laser I cranked it all the way up to 100%.

2- Use your air assist. This is absolutely critical. Without air assist you will get large amounts of that aforementioned resinous ash on your lenses and mirrors and it is extremely difficult to clean off.

Ash. Ash everywhere. Don't breathe this. You'll probably die.

3- Set the feed rate very slow. This is to ensure your ventilation and air assist can keep up with the production of fumes and ash. If you go too fast you risk it building up faster than it can be dealt with. Also, a slower feed results in cleaner lines and less melting.

4- Use higher DPI/PPI and do multiple passes. I had to do this because at only 40 watts of power, I needed every bit of extra heat I could get to have a nice deep engraving. Also, unlike wood or plastics, the rubber doesn't lose much detail so the higher resolution is nice to have.

Once you have engraved the pattern to your liking, cut it free and immediately clean it. You need to use soap and water and a toothbrush. This is because the ash can become embedded in the cooling rubber and become impossible to remove if you wait too long. Once it's clean, spray the rubber portion liberally with adhesive, wait a moment for it to tack, and stick it to the foam. Then put it under some heavy books to dry, foam side up.

Latin and Electronics. Heck. Yes.
After 30 minutes to an hour you should be ready to cut it out. Trim as close to the edges of your design as you can, to reduce over-stamping, and mount your new stamp to an acrylic or wood block with double stick tape. Since the stamp is brand new, you may need to use it a few times before it softens and holds ink well, but this is normal with all rubber stamps. Once that's all done, start stamping and enjoy!

A nice clean print.
This is over-stamp from a first try. Trim carefully to avoid this problem.

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