[djh82uk]

Hi Guys

Im trying to make a spring loaded engraving tool for pcb's

It is to be the type that has a shaft and fits in the spindle, basically an 8mm shaft with a chamber holding a spring, and then a sort of collet system that holds the engraving bits, the collet section can move up and down.

However the problem im having with the design is making sure that the collet section cannot rotate independantly of the main shaft, but it does need to move up and down.

Now the most logical way I can think to do this is to have 2 slots in the shaft and then tags/ears or whatever you want to call them on the collet section, so it can move up the slat, but not rotate.

Now I have a Taig CNC Mill and a Manual Sieg C3 Lathe.

How do I make it? I was going to turn the shaft and bore it out etc on the lathe, but how can i make the slats? obviously it will be on the mill, but how can I ensure that it starts cutting ont he highest point of the radius?

Does that make sense?

any advice greatly appreciated. Im kind of a newbie btw.

DJH

[bclark6716]

If you want to make your own, use ball bearings instead of ears. I wanted to make my own, but found one ready to use at www.2Linc.com Works great and they have a good selection of bits at a reasonable price.

Brian

[djh82uk]

Hiya

Yes ive seent he 2linc ones, but my wallet cannot stretch that far at the moment

I like the ball bearing idea, but still, how do I make the grooves/slats for them to fit in? I do not have any edge finders etc btw

DJH

[fretsman]

Using a dowel pin in a chuck works like an edge finder. Just turn the spindle on and move the cylindrical part your going to mill, into the dowel slowly and when it starts rubbing the dowel, you lift the z axis and continue to go half the diameter of the dowel, zero, than go half the diameter of the part and you're at the center of the part.

Hope that helps-

[djh82uk]

Thank you, it's the ability to to find simple answers and to not overcomplicate things that I lack..

Thanks Again

DJH

[dgoddard]

Don't know exactly your needs, however there's a design for a spring loaded drag engraver for CNC mills shown in the Fall 2007 issue of Digital Machinist. You may want to check it out. I have plans to machine one in the near future (soon as can find the time).

[BobWarfield]

Check this one out: http://bbs.homeshopmachinist.net/showthread.php?t=27011

Best,

BW

[cbcnc]

You're talking about two different kinds of engraving.
One, simply dragging a burnishing tip over your material. It just pushes the material out of the way. Like the one in the Bob's link above.
The other way is like using the one that 2Linc offers where you use a std. engraving cutter at rpm and it cuts. The cutter is meant to glide over the material with a consistent down force. That's the reason for keeping the collet from spinning in the spring loaded tube.
Here's another link to a different way where the whole spindle is on a spring. He mounted the spindle on a slide.
http://www.flickr.com/photos/11236729%40N08/

Chris