I had another batch of parts to run which required engraving text. The first time I did these, I used a center drill in a drill chuck. It tended to wander and was not a consistent width in unfinished hot rolled steel face. I wanted something better.
I looked at other ideas. There are commercially available engravers for upwards of $300. It is hard to justify going from a $3 center dill to a $300 plus unit.
DMF_TomB over at Practical Machinist had a good idea for a homemade spring loaded tool.
I didn’t have the same parts as Tom so I made my own design using what I had. I had some 3/4″ drill rod and brass material. I figured the brass would provide a good bearing surface. Steel on steel would most likely work fine for the amount of work this will see. I also had a Jones Spring assortment kit from Mcmaster.
There are only two machined part (not including spacers). I wanted to be able to quickly switch materials so I put a set screw in for clamping the bit. The M6 bolt holds it all together. There are some spring pre-load spacers made from 3/8 rod with clearance for M6 drilled thru.
I made the fit as tight as possible between the plunger and the drill rod body. This reduces large chip loads from an off center tiny cutter tip traveling into new material.
I tested it on aluminum soft jaws. I then made a doggy tag.
It also works in SS with carbide,. I broke the tip halfway thru but it still looks good. I think I need to lesson the spring force and slow down the feed rate. It is probably better to start soft and slow, than hard and fast.
If I had to do it again and I had more time, I would probably buy a straight shank ER11 collet chuck and design a spring mechanism around it. You can get cheapies off Ebay or a good one from Maritool.
The Solidworks files for this are located here. Have at it.