Another Electro Etch Question

Bob and others as may know.

Well I built Bobs' electro etch machine, got the supplys and used my contact printer to make a stencil. So far so good. I etched my latest knife (welded cable) and didn't get as clear a mark as I would like. The lines are all nice and sharp. However, I think, the mark needs to be deeper.

So my question is.......

Are there any sort of guide lines as to how long to etch the mark? I can't see clearly thru the stencil. So I expect it's a matter of learning how long to etch.

Scott B. Jaqua

Scott,
About the only thing I can suggest is try it on the same steel if you have some scrap or try it on the tang until you feel comfortable with it. I'm not at all familure with the machine you built. Are you able to switch to DC, I've got a Marking Methods machine and you've got a choice. DC is used to get a deeper mark. Ray

Let me preface this remark by saying that everyone has to develop methods that work for them.

When I was learning to use my etching machine, which is a Marking Methods machine, I wanted to get a deep etch. So, I worked out that I could tape both sides of my stencil with scotch tape. After I think I'm done, I very carefull peel back the top edge of one side and examine the etch. If it is good, I'm done. If it needs to cook some more, I hit it again. I test the depth of the etch by feel with a round toothpick. You should be able to get consistent results, i.e., a certain number of impression cycles gives you a certain result.

The danger of peeling the stencil back to take a look, is that if you hit it again you will get a 'double' or blurred mark if the stencil moved out of registration. I am careful to make certain that the stencil is 'tight and flat' when I tape it up and I then only peel one side back partially. If the side comes completely loose it's a crap shoot whether you have good registration if you try to tape it down because as you stated you can't see through the stencil.

I've not had a problem using this technique, but there is the risk...

Also, as a matter of terminology:
I believe that if you use AC current, you're making a 'mark.' If you use DC current, you're etching -- that is you're actually removing metal.

I don't think that a mark will ever have any 'depth.'

The machine I built was to Bob Warners plans. It has the option for both AC and DC operation. On welded cable or pattern welded blades I was only planning on using the DC to remove metal. For plain steel blades the plan is to use DC to etch the mark and then use AC to blacken it once it's the correct depth.


Scott B. Jaqua

DC current removes metal by just eating it away. AC if you think about it liiks like this ~, and one one side of a center line (don't remember which side) the metal is removed and on the other side it is put back on. This is what "Marks" the blade because the metal turns black when it is replaced. Therefore, you need to practice on scrap material of the same type of your blade until you get the depth you need by using the DC side, once the depth is obtained, convert to AC and mark it.

You need to remove metal in DC mode in small increments. Just get on it for a couple seconds and get off. If you get on it and stay on it, you will get a fuzzy mark and TEAR UP your stencil. Just get on for 3 seconds, get off off for three and go back on. Test it until you determine how many "cycles" you need to get the depth you want. Make a note of that and use that note every time you mark a blade. I normally do three DC cycles of on/off at three seconds each, then go to AC and mark it.

Another thing that I think is important. EVERY time I mark a blade, EVERY TIME, I always do a practice mark on another piece of metal first. As some of the more experienced people here will tell you, sometimes your stencil can get damaged, no matter how careful you are. For the photo stencils, all you have to do is leave them in ultraviolet light too long and they get brittle and can get small cracks. When you etch your blade, these small cracks become BLACK LINES added to your logo. If you etched them in really deep, you will have to regrind to get them out. If your blade is absolutely perfect and you now need to go back to the grinder, it can ruin your day. It takes a little longer and some people may see it as a hassle but I look at it like this. You just spent this many hours "XXXXX" making the knife and getting it good enough for you to be willing to put your name on it. NOW you get in a hurry and ruin it because 5 minutes was too long to spend on marking it correctly. The pieces of steel I use for practice are just ground to 220 on the platten and marked. After the piece is full of marks, I go back to the grinder and clean it all off and am ready to go again.

Your stencil makes a difference also. A photo stencil acts different than an impression stencil. Impressions stencils are not (in my experience) as clear as photo stencils. Therefore make sure your stencil marks good and gives clean lines on your practice material before attacking a blade with it.

Bob,
I might have missed it on your site or here, What photoresist do you use and where do you get it?

Thanks,
PaulD

Here is a thread that has all of the information about where I am currently getting stencil material.

Photo Stencil thread

Thanks Bob,
Between your web site and your comments here, I'm sure to have some good results early-in. Now I have to justify the expense to the "Boss"

PaulD