Questions about drag etching

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Cut and Dry
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Joined: Mon Oct 07, 2013 8:56 pm
Model of CNC Machine: Zenbot 4848

Questions about drag etching

Post by Cut and Dry »

When using a diamond engraving bit on acrylic for a edge lit sign what kind of parameters should I use? How deep should I have it set to carve? Would I set the bit zero with it barely touching the workpiece ? Should I use the heavy spring or the light spring? Should I do a rough out pass then a final detail pass using the same bit but maybe changing the spring? Would it be better to use photoVcarve, cut 3-D, Vcarve Pro or a combination of photoV carve and Vcarve? I have seen some really nice examples of what can be done with this software; however, I have not had any luck in this department. I am using this bit http://www.tormach.com/store/index.php? ... &ref=32447
I have carved out some really nice wooden signs and created a few decent lithophanes (still have some things to figure out when doing these); but have not had any luck at all carving photos into wood or carving on acrylic (even after watching the videos). And when using the cut 3-D software everything turns out with too many lines where it has cut the pattern, of all three programs I have, the cut 3-D has been the most disappointing (basically useless since I do not have hours upon hours to detail sand out the lines).
For the most part I love my software and my CNC machine, but I simply can't get the hang of some of the projects without some help from the folks here. I would greatly appreciate any suggestions or advice on how to complete these etchings or how to get better results from the carve 3-D program. Thank you in advance for your tips and advice.

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Xxray
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Re: Questions about drag etching

Post by Xxray »

Looks like a nice tool, couldn't handle the .75 shank though.

Don't overthink, its pretty simple. Mine have adjustable tension on the spring, no heavy or light ... I set mine medium ! Probably won't be too much of a factor either way, offhand I'd say for plexi light, metal heavy. Set depth about .009, lower tool to material and compress the bit some, then zero the Z there and you should be good to go.
Far as software, vcarve [aspire] or cut 2d work fine, cut 3d would be useless for etching. Reading your post further, if it photos you are trying to etch I won't be of much help, far as I know a drag bit is not the proper tool for that job.
Doug

BDM
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Re: Questions about drag etching

Post by BDM »

I'm not clear either what you are trying to do. Cut2D or VCarve-Pro can do all sorts of things with a diamond drag on acrylic. But a diamond drag isn't going to work with photovcarve or Cut3D. Assuming you want to do a picture on acrylic with PhotoVCarve, you can use what I did on this project (also includes some diamond drag work):
http://www.vectric.com/forum/viewtopic.php?f=16&t=17340

If you are getting a lot of lines that need to be sanded in Cut3D, it sounds like your stepover is set too high or you're using the wrong bit. If set up properly, Cut3D will create a very smooth object, but isn't designed for pictures, only 3D objects.

If none of this helps, give us some more details as to what you want to do.

Cut and Dry
Posts: 19
Joined: Mon Oct 07, 2013 8:56 pm
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Re: Questions about drag etching

Post by Cut and Dry »

BDM
Your example is exactly what I'm trying to do. I want to cut a picture of an American flag with an eagle in front of it (a jpg) and put some writing on it for my brother-in-law's retirement. I have a pretty good assortment of bits including a 1/32 nose bit. I even have some extremely small endmill bits. However, any time I tried to carve any kind of a picture on plexi or wood it turns out just looking like a mess. I have tried everything from micro v bits, end mills, engraving bits and ball nose bits.
I simply cannot get any kind of a picture to turn out, with the exception of lithophanes which have turned out decent but still has a lot of lines. I have tried various depths, step overs, speeds and everything else I can think of? Did you reverse the image and cut on back or did you cut on the front? I have also tried doing them in photoVcarve and Vcarve pro.
If you don't mind me asking could you give me a rundown of exactly how you accomplished such a nice piece. Like bit size, step over, speed, depth of cut, angle of cut, did you crosshatch and the type of program you used. I have been messing with trying to get this right for over three weeks (many wasted pieces of plexi) and I have only one more week to complete it.
As far as cut 3d I will just have to back shelf for a while until I have more time to work on and figure out why it's leaving so many unsandable lines. Thank you in advance for any help or assistance you can give me.

BDM
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Re: Questions about drag etching

Post by BDM »

First off, make sure you have CAST acrylic, that will make all the difference. For any picture, I use PhotoVcarve and then Cut2D for the lettering. I think most of my settings were in the thread, but to summarize, I used 1/4" acrylic, a maximum depth of .08", 50 ipm, and 15% line spacing with I believe an angle of 33 degrees and as I said earlier, a 1/16" ballnose bit. I did not cross hatch. I did cut it from the back, but that is more of a personal preference (and easier to keep clean).

If possible, maybe you could show us your design and the settings you were using for the "best" one in acrylic? If you also have lines in lithos, you're not setting something correctly, with my guess being the line spacing (should be somewhere around 8-15%). Wood is a different story.

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martin54
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Re: Questions about drag etching

Post by martin54 »

Which part are you having the problems with the picture or the text? As BDM says you will get far better results using cast acrylic as opposed to extruded. Acrylic does seem to be less forgiving than wood if you get the speed & feeds wrong & that will vary from machine to machine.
Posting a file with settings is often a good way to get help as people can look to see where you are going wrong, plus a photo of a finished job to see what's happening. I would put cut 3d to one side for now & spend some time learning how to use the other 2 programs unless you have 3d work you need to get done.

Cut and Dry
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Re: Questions about drag etching

Post by Cut and Dry »

BDM

Thanks for the info. I finally got one to turn out decent. It is not perfect can still see some of the lines. I could not get the drag diamond bit to carve the letters so I had to use a 1/32 ball nose. It is not perfect but at least it was good enough to give to him for his retirement from the Army. He was please, I made it with a 44 color remote so he can change it to almost any color. He was happy with it and that is all that counts. I do not know what the problem was but I followed you advice and came out with this. My technique still needs work but at least I have the basics now. Thanks again
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Cut and Dry
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Re: Questions about drag etching

Post by Cut and Dry »

The Pictures would have shown up better but I had a window behind me that was causing a glare and too much back light. they look pretty good in a bulb lit room. Thanks again for the infomation.

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