I documented how I make the compass inserts (look at the Travel Pen version 2 post if you do not know what these are).  I am sure I violated every good machining practice know to the modern world.  So no laughing or scolding!

First I needed to figure out a cheap way to re-sharpen the carbide engraving cutters.  I know you should use a diamond wheel but like I don't have a diamond wheel, so anyhow I made a fixture to grind the engraving cutters using a linear slide and a dremel:



Here is a better picture of the linear slide.  I mount the cutter in the dremel turn it on low and move the slide into the grinding wheel.  A few sparks later and the cutter is sharp.



I start out by mounting a lathe chuck and putting a wood post in the chuck that is the same diameter as the 3/4" sterling silver disks.  I face the wood off to ensure it is flat.  I use maple which is hard and somewhat durable.



I then super glue the sterling silver disk to the wood post and indicate the disk to find center.  I also take a cut around the outside of the disk with the cutter in the mill.  This cleans up the outside since they are punched out and ensures that everything is on center.



Here is a screen shot of the Mach3 program with the compass that is to be machined.  We're ready to rock n roll!



I then put in the engraving cutter and start the program. This is a shot with my miniature high tech coolant system running:



As an aside here is my miniature high tech gravity feed cooling system.  Note the gravity feed is located conveniently on a near shelf.  The source container doubles as a high tech misting system I bought at Wal-mart.  The precise diameter flexible tubing (I am told it is also used on aquariums) runs to an extruded square brass tube that is held to the machine head with an indicator clamp.  If you look real close to the left of the coolant source container you can also see my high tech air pump I use when I cut wood (I am told is is also used in aquariums!)



And of course you need a high tech recovery system, no waste here!



Here is the disk after the first pass;



This is how I remove the disk after the machining is complete.  I use a sheet rock knife and wedge it between the disk and wood and it comes off easily.



This is a picture of the finished piece.  The flat one closest to you is the one that was cut I tweaked the image a bit from the last one.  I then take the wood block and aluminum shaft and bend the disk to the proper curve.  Once that is done I then enamel the engraving as you can see as the blue curved compass.  This one has not been buffed so it has a mat finish.



The last image it the cutter after the engraving is complete.  Not much of the point is lost.



Any comments let me know.  Thanks for looking.

Dan.

This is great Dan. Will you ever be able to retire? Seems like you are putting loads of money in to the High Tech gadgets. 

Another fine example of what can be done with a little bit of money and a lot of thinking. Keep up the good work.

Brett

Very cool Dan!  So your engraving cutter is just a sharpened carbide rod?  Do you spin the spindle or does it just scratch the pattern?  I'm surprised how well it works without any cutting edges.  I had thought about strapping one of those vibrating engraving pens to my spindle to try something similar but it is a lot easier to line things up with a cutter true to the spindle.  Does it only work because the silver is so malleable?

I  use a single end carbide split cutter from Rutland Tools:

https://www.shoprutlandtool.com/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&storeId=10001&productId=24702&langId=-1


I run the spindle as fast as possible which is about 2500 rpm and I go 1.2 IPM and I only remove .005 a pass.  Figuring each pass is about 5 minutes it takes less then 30 minutes to run the complete cycle.  I could be more aggressive in speed and depth of cut but I would rather wait then have the cutter go dull.

Aha, that makes sense!  I should have guessed the backside was flat in those images 

Very nice work indeed!

Hey Dan,
    I know nothing of those engravers, this is just food for thought. Slower on the feeds and speeds isn't allways better, only to a certain extent. You can burn a cutter up really fast if the feed,speed,depth of cut aren't right. If you haven't talk to your supplier about the feed, speeds, depths, chip load, you might want to. In any case, your doing some fantastic work.


Brett

Brett,

I found this info on the web http://www.2linc.com/engraving_assistance.htm#Spring%20Selection and it is consistent with other info that I have read that the spindle speed should be well above 3000 rpm. 

I would really like to get a high speed spindle but I am sure the cost would be prohibitive.  I did think about using a Proxxon mounted off center but I have so little travel and table room that it is not practical for a lot of the machining I do.

Dan.   

Hello dfurlano
very nice work .for the dept of the cut you could go to .010 no problem, and you can fill the lines with engraving filler it comes in different colors very easy to work with. when i do hand engraving sometimes i use it with different colors other times i use printer's ink to fill the lines.

Marcel

Hey Dan,
     Ever think of making another head with an off the shelf router in it?

Brett

Marcel,

I will try 0.01" on the next piece I cut.  You are probably correct 0.005" is a little light.

Brett,

Since I am not going to retire anytime soon I was thinking of another high tech solution!

I am thinking of buying this flex shaft:

http://www.proxxon.com/us/images/produkte/28628.jpg

And see if i can run it through the spindle like I did with this dremel flex cable:



Then I would just need to mount the Proxxon grinder http://www.proxxon.com/us/images/produkte/38481.jpg and make a collar clamp that would mount around the spindle hole and clamp the flex cable in place.

What ya think?

Dan.