Cermark on rounded chrome cover?

[Rick Rokicki]

Don't know a whole lot about laser engraving yet but is the reason that my lettering won't stay on w/ the cermark because it's not a flat surface and the further from the center that I go the more the beam bounces off of the shiny material? In the picture it's supposed to say untouchables above the logo, but it flakes off when being lasered. It is very faintly noticeable. Any help would be appreciated.

[Bruce Volden]

Rick

On a flat plane the focal point remains constant. When a surface curves that changes the focal point-sometimes minutely and not noticeable. I, personally, avoid chrome because of hit and miss results-even when totally flat! But when it does work it really looks nice~good luck!

Bruce

[Anthony Scira]

I noticed there are also formulations (Cermark/Thermark)for diffrent metals. Are you using the one for polished surfaces and chrome ?

[James Rambo]

I did this a about 3 years ago and lost my pictures.This is on my older brothers Harley. My sister took this picture (sorry) about 1 year ago. I had a little trouble with it as you are. I ended with a series of engraving in a circular pattern from the center outward, that I did without moving the part within the laser.

[Sean Bullock]

I have spoken to the engineers at Thermark a number of times regarding their products. Some time back I was trying to mark on chrome tools from China and was experiencing a similar problem with the lased area wiping away as I cleaned it. The response was that the quality of the chrome plating will have an effect on the quality of the marked surface. Sometimes the lower quality chrome will not take as well to Thermark.

I would suggest to re-focus at the point where you want the lettering to be. What is the differential of the curve from center to outer lased area?

What Thermark product are you using?

[Gary Hair]

Don't know a whole lot about laser engraving yet but is the reason that my lettering won't stay on w/ the cermark because it's not a flat surface and the further from the center that I go the more the beam bounces off of the shiny material? In the picture it's supposed to say untouchables above the logo, but it flakes off when being lasered. It is very faintly noticeable. Any help would be appreciated.

I had similar problems with a large aluminum piece, 30" x 30", that was very highly polished. Sean suggested I use the Cermark/Thermark specifically for polished surfaces. Unfortunately I didn't have time to order that and had to try something else. I ended up masking, sandcarving, applying cermark and lasering. It turned out spectacular! It seemed that I had two things going against me with that piece - one was the polished surface and the other was the size - that big hunk of aluminum absorbed heat very quickly and the cermark just wouldn't stick to the polsied surface.

My suggestion would be to slow way down and generate as much heat as possible. You know you are too slow if the Cermark turns bluish gray instead of black. If possible, setup a test piece and laser a 1/4" square at various settings, starting with the one you normally use and slowing it down from there. When the marks starts turning bluish gray then you know you have reached the slowest speed.

Gary

[Bill Cunningham]

My experiance with Cermark is a little out of focus, and the stuff won't work.. I would imagine the more powerful the machine, the better it will work. My 35 watt Epilog at 1200 dpi, and 4% speed, will barely make it stick when the focus goes out by 1/16" .. The center tube in the picture below is a good example of the curve causing a heat drop off.. By slowing down a lot more, I was able to make the logo permanent in the other stainless tubes..

[Dan Starr]

Rick,
It is possible to do derby covers as you have pictured there. First rule of thumb is make sure it is either authentic Harley Davidson chrome or Drag Specialties chrome, they seem to work best. Cheap chrome products are not predictable. Chromed alluminum parts can also be unpredictable. I've found that high power and real slow speeds work best also as far as focus goes it's better to be to high than to close so set your focus at the top of the derby cover. Here are some good examples http://www.hogsink.com/gallery.htm