Spring Loaded Engraving Tool

Hi All,

I just wanted to show my variation on a pretty common homemade engraving tool.

Some of the things I wish to engrave are not very flat, and not amenable to being made flat, think AR mag wells.
So I wanted a rotating spring loaded engraver, because drag engravers don't go deep enough in some situations.

Mine is very similar to many others you might see by googling them, but I did do a couple of things differently than most of the ones I've seen. That would be using a commonly and inexpensively available ER 11M straight 10mm shank collet chuck for the sliding portion of the tool, these are in the $10 range on eBay. I also added one of the MSC clamping collars to the shaft to make it TTS compatable.

I decided to go with an external spring, so I also added a 10mm clamping collar to the chuck shaft to give me spring tension adjustment without removing the tool from the spindle.

Terry

Nice job!
I have my eye on similar tooling. "drag knife" I have a need to cut thin soft materials precisely and this would do it!
Thanks for sharing

MD - have you seen this tool?

Drag Knife for CNC routerDonek Tools

I have one and it worked fairly well for a gasket that I cut in paper, but I haven't used it much since then..

The spring loaded on the outside makes more sense now I see it those little collet spindles are pretty good I have one need another ,this is the 6 mm shaft one I made it's a passable tool does a nice job for $5, distance is a factor I was having trouble with great work .
Attachment 290618

Nice job Terry.....

Robert

Do you any pics of some engravings done with it?

Terry;
Nice design. Would it be possible for you to post some pix of your engraving work with this tool? I attempt to engrave magwells but they always turn out to be not very professional looking!
Thanks.
Bill

Hey guys,

Sorry, I've been away from the computer for a few days.

I don't currently have any lowers that need engraving, but when I get the next one I will take some shots after engraving.

This is a rough attempt to simulate the uneven surface problem, it's a piece of very thin and not especially flat, AL sheet metal, double sided taped to a block. I blackened it with a sharpie, just for contrast, so please excuse the crappy look!

I think the tool did pretty well, it's just one of those 90 degree half flat tools that are real common. I cut at 5000 rpm, but as most of you know setting the depth of cut with a spring loaded tool is kind of hit or miss, you can't set the depth you really want, or the spring action won't help, and too low you risk cutting too deep. If anyone has a good method to do this without a lot of trial and error, I'd really like to hear about it.

Terry

MFchief,

Being a teacher, I would love to have a set of drawings for this. Something that uses a lot of the lathe skills taught and a tool they can take and use forever.
Great design!

Hi,

Sorry to say but I don't have any drawings for this tool.

As I said, my goal was to use as many off the shelf parts as possible, and everything is a standard purchased part except for the body. The body is just a piece of 3/4" drill rod bored and reamed for a close fit on the collet chuck, with a slot cut for the roll pin to engage, in order to make the collet chuck rotate with the spindle.

If your thought is to make the entire tool from stock, it would require some pretty close tolerance machining of the collet chuck, especially the tapered bore for the collet. You didn't mention the skill level of your classes, so that may or may not be something you would want to do. If you want to do it the way I did with stock parts, making a drawing for just the body should be fairly straightforward.

Terry

Thanks for replying, Terry.

I have the students make a spring center and I'm going to try making another insert to hold the diamond dresser or engraving bit. That would make the project multi-functional.

One trick I learned from John Saunders that is turning out spectacular results is to use a fly cutter (on flat surfaces only) and skim over the engraved surface after you engrave it. The results are nothing short of spectacular. You have a beautiful engraved piece that you can not even feel the lines with your fingers when you run them across the surface. What has worked best for me is to simply flycut the surface to be engraved. Do any other milling, contouring, or drilling as needed and the engraving, then simply run the previous postprocessed file for the orginal fly cut with no modifications. I was astonished with the quality of the finish after engraving. Just be careful to not "mess" with your Z Zero... I did a couple of times and ended up "erasing" the engraving and getting to start it over.. LOL..

Another way to engrave a non-flat stock is to use a program like Autoleveller (Autoleveller | CNC workpiece levelling). It probes the stock surface and then adjusts the input G-code for the height variations. This method gives you precise cutting depth that does not vary with the RPM or the feed speed.

That autoleveller software looks pretty interesting, would be useful for surfaces like PCBs for sure.

Terry

These spring loaded homemade engraving tools can be very useful, check this one out: https://youtu.be/vMG9o9bw22w

I checked the autoleveller site, it says it works with Mach 3 and LinuxCNC. Has anyone tried it with Pathpilot yet?
Terry

Quote:

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Originally Posted by MFchief

I checked the autoleveller site, it says it works with Mach 3 and LinuxCNC. Has anyone tried it with Pathpilot yet?
Terry

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No one seemed to mention PathPilot on the Autoleveller forum, you should probably ask that question there. In principle, you should be able to make it work, as long as PathPilot supports a probing move (such as G31 in Mach3) and a file write command (such as M40/M41 in Mach3).

Thanks, I will check out the forum, or I may just download the free version first ant give it a try LoL
Terry