[GeorgeRace]

For some time I have been engraving Experimental Aircraft Data Plates. No matter how well I clamp down the thin aluminum sheet, there always seems to be an area that is slightly bowed above the work surface. When you are engraving to a depth of .003, there is not much room for error! Sometimes I have enough difference in the depth of cut to easily see, and I need to start over on a new piece.

I have considered a spring loaded tool holder for some time, but just could not see spending the money to buy one. All this has brought me to the point where I decided to build one from scratch. My design is similar to ones that I have seen, over the years, and provides me with a way to do PERFECT engraving every time.

I have put all the details on my web page. There is a Dimensioned Sectional drawing there so you can make your own if you wish, and I also have them available for sale, if you are interested.

Here is the link: Spring Loaded Engraving Tool Home Page

George

[coherent]

You're right, trying engrave with tiny small depth tools is a pain, even on well aligned precision mills. I finally made a couple of spring loaded bit holders and have been really pleased. I found the "keep it simple principle" worked the best. A number of the designs I've seen folks use a number of body parts etc. (example is the one in the fall 2007 Digital Machinists) I'm not saying they don't work well, but I came across a simple single body design, bored out to 1/8 on one end so the bit sits inside and the other end bored and tapped to a large enough depth/diameter for the spring and a hex head screw to hold it in & provide adjustment. I made one out of aluminum and it works great with both the diamond drag bit and the tiny rotary engraving bits from dremel. If you have any 1/8 micro bits with the little plastic depth collars (like the red one in your photo), just press it off and put it on your bit to mount in the spring loaded holder. A tiny bit of epoxy or JB Weld will hold it in place on the bit shaft. If you have a small lathe (or use the mill) you can make one in a few minutes for nearly nothing. Your only real cost is the bits, and J&M Diamond Tool has the 120 deg, 1/8 by 5 in diamond drag bit for about $12. Cut it to whatever length you need. The small rotary dremel engraving bits are about 2 for $5 at the big box stores. A little experimentation with spring and/or inch per min cut speed and you'll find you can get about any look you want! The rotary bit is great for bolder or larger lettering and designs and the drag bit allows you to engrave as small and fine of lines you'd ever need.

[GeorgeRace]

Yes, keeping it simple is always best.
Thanks for all the suggestions and ideas.
The holder that I am making is quite simple, but with the drilling, boring, and polishing does take some time to make. I do think it is a sound design that will hold up to use really well. I do most of the work on a small lathe. I use the CNC to cut the slots for the mounting cap screws to slide in, as well as the 4-40 threaded holes.
Thanks for your comments,
George