In addition I positioned the hour numbers closer to the hour hand and added minute's further out so later she could use it to teach our son how to read a clock.
In hindsight I would expect this to be easier using anodized aluminum instead of brass. Brass tarnishes, scratches, and even fingerprints leave a dark stain. So there was a lot of extra steps to accommodate this material that anodized aluminum would've skipped and it would've burned easier on the laser and maybe even looked better/cleaner. Some steps would need to be moved around, but I'm just going to focus on how I did it and/or would do it again with the same materials.
Yes, this is an extremely belated mothers day gift (if you look at the posted date). As with most things that are new, I had no idea how much time and work it would take when I started.
Step 1: Tools and Hardware I Used
1. Epilog Laser Fibermark 50 Watt
My work just got one, so what better way to train on it?
3. Clock Parts.
I got mine from clockparts.com, had a hard time finding their instructions for what order to mount which washer, nut, ect. so I e-mailed them and got the attached picture:
Since my material was brass I went with the black ones so there is some contrast.
3.3 Back (optional to cover battery compartment):
4. Material you will make clock out of.
I used item 88825K34 from McMasterCarr
12"x12" Corrosion-Resistant Bronze (Alloy 220): This simple copper-zinc alloy, historically called commercial bronze, is often used for marine hardware, weatherstripping, and ornamental trim because of its finish and good corrosion resistance.
Because I got brass I also needed:
4.1 Brass polish (http://weiman.com/Products/Silver-All-Metals/Brass-Cleaner.aspx)
4.2 Micro-fiber cloths (I got a large pack of these at Home Depot)
4.3 Glossy Clear Coat Rustolium (I got mine at Home Depot)
5. Mill with prototrak
6. Painters blue tape
Step 2: Design Your Clock
I put a circle in the center so that I can locate the center later when drilling the clock kit mount hole and cutting the material round. Remember your final clock mount hole is pretty large, and you need your center black dot to be large enough to spot on top of the photo.
I exported to PDF to put into Corel Draw.
Instructables is erroring out when I try to attach the slddrw file, so you may need to make a drawing file with the hands suppressed or just use the PDF.
You may notice on mine the numbers rotate around the clock face so the 6 is upside down. I considered a more traditional look, but what's the fun in making something from scratch if you can't do it differently?
I also considered putting a line under the 9 and 6 (or over in this case) and the 12 and 3 just for symmetry, but decided this design was a good tool for teaching context to a child.
I tried printing directly from solid works after importing the photo, but it turns out solid works sucks for printing photo's and it was all distorted. Thus why I imported everything into Corel Draw.
Step 3: Edit Your Photo
Then I applied the "photocopy" filter, with the details turned up to max.
I then imported the result into Corel Draw. I made sure to "send it to back" so that the white area's don't overlap on your clock.
I tested many different versions of the image. The image only feathered without a filter burned so that it looked good in the light, but creepy when not reflecting light. Inverting the image only made it look creepy with light, but good in non-light. Admittingly all these tests were at my early power/speed settings, I'd like to see the image without a filter at the new settings I discovered.
Ultimately I thought something that uses the edges (like a vector/trace) of the image would be better for burning an image in mono-color. So I went through the filters, and under sketch found photocopy. Tried 5 different versions of maxing out detail, darkness, or both and some in-between and found that max detail and default darkness looked best.
With a name like "photocopy" you would expect it to just degrade the image like a photo copy would, but it was under the category sketch so I tried it.
Step 4: Sand and Polish
Once you finish polishing the clock is ticking. Just leaving the project out for a day or two would cause some tarnish to show. So personally I polished one more time just before the clear coat.
Since handling and shipping of my brass plate scratched it up I did an extensive amount of sanding with scotch bright pads and polishing paper, trying to get the scratches to not show, some of my sanding was also done after laser etching. In hindsight I should have been more careful, but I had no idea how easily brass scratches. An automated sander of some kind would've been nice as well.
Step 5: Burn the Image
With both images imported into Corel, burn a test piece into a corner you're going to cut off anyway, or just some scrap sheet metal.
The final settings I wound up with for my brass material was 10% speed, 100% power (at 50 Watts), and 10% frequency. This was enough to even cause a recess in the material, and was dark enough to show up at any angle.
I also turned off Center Engraving so I could just place the image where I expect it to be.
When ready, burn the full size. For me at my size and settings it took over 2 hours and 40 minutes.
Clean with paper towels and an alcohol water solution.
I turned my part around and burned a message into the back (make sure to leave room for it to show around the clock motor):
May this moment in TIME be forever BURNED into your memory.
-Wife and kids name, date and location of picture.
I found that for the most part everything burned similarly on aluminum sheet metal as brass sheet metal. With the exceptions that any bowing in the sheet metal caused the image to degrade and even disappear, but since my brass was rather thick I didn't need to worry about that with my final product.
I also tried several settings and multiple passes. Then I *cough cough* opened the instruction manual and *cough cough* read it. And it suggests for metal turning down your speed and up the power. That's when I tried the above settings and it looked great. Reading instructions ... who would've thought?
Step 6: Machine Hole and Final Diameter
To prevent scratching during cutting operations cover in blue painters tape, with the exception of the center hole.
Find a scrap piece you can clamp your mill vise onto, use double sided masking tape to hold your clock material onto the scrap piece and use a rubber mallet to compress/adhere the tape. Note, I taped nearly the whole surface area and it proved to be too much as it was very difficult to remove. You may want to half that or so. Perhaps also placing something under the material to use to pry off later would've helped as well.
Locate center using black dot you burned. Center drill it, then drill it to your final size to fit your clock kit.
Cut the outside diameter. For this we programmed the Mill's programmable prototrak system using the hole we drilled as the center of the circle we're cutting.
Note, if when you located your center you were off, you'll notice that the distance from the outside line to the edge of the brass will not be consistent. In this case I recommend making the overall diameter smaller to get rid of the outside line so it's less noticeable.
When done, remove from scrap piece using WD-40 to soak the tape off, and some gentle prying.
Remove painters tape.
Remove any burrs using a finishing scotch bright wheel. Be careful to not scratch, but don't leave painters tape on for this as it could get caught in the wheel and/or load up the wheel.
The bit we used was rather small because I wanted to preserve the corner test pieces and make coins out of them, but if you either don't have them there, or plan ahead and make them further away, you should be able to use a larger bit and not need to be so slow and gentle.
Step 7: Polish and Clear Coat
Then following the directions on the clear coat bottle to apply your clear coat.
Flip over and do the same on the back side.
Note, the instructions say that it "can be handled" after 30 minutes of your last coat. So after 30 minutes I flipped it over and did the back side. Unfortunately some of the microfiber cloth I had it on embedded in the clear coat. So I would either find a way to stand it up, put something hard behind it you don't mind getting clear coat on, or give extra time between the front and back. In addition I found a few particulates in the clear coat. So perhaps covering it would've been in order.
Step 8: Mount Clock Kit
In my case I also cut out the small test pieces as coins.