edgelit signs

[Chris Hawks]

Hi Guys. I'm new to the forum but not to V-carve and I'm trying to get into the edgelit lighting also. I have made a few but not 100% happy with them. I'm using a 120 deg drag bit on cast acrylic and it does good but I either get some streaking or light and dark areas in my images. I've tried different depths, speed ,step overs etc. Could someone point me in the right direction on something maybe to look at or maybe settings that work for you. Any help would be appreciated.
Thanks
Chris

[highpockets]

Chris,
I'm also new to the edgelit signs. I had a problem with one sign that using Fill at any depth, step over just would not get some areas. I would have a outline but only partial fill. Try using the Hatch setting. Worked for my situation.

[Chris Hawks]

Yeah I thought about trying the hatch just haven't done yet. It's just weird. Say you are engraving a persons body and it starts at the left foot and works its way up the leg and when it gets to the mid section it will start down the right leg and finish that part of the leg out. The right leg will look different than the left leg almost like a lighter reflection than the left. I have an example but I can't seem to post it on here. Do I need so many post before I can upload an image?
Thanks

[highpockets]

I believe you should be able to upload a picture. Look at Upload attachment below the message area. Pictures are limited to 2MB so you may have to reduce the size of you picture.

[Chris Hawks]

I'll try the hatch tomorrow and post back my findings.
Thanks

[martin54]

If you can post a picture of what you have engraved I am sure one of the experts like Xxray or Dwayne will be able to give you an answer
Although the limit is suppose to be 2 meg for jpeg files I have read on here that people have had trouble uploading at that size so based on that I would probably make it less,
I haven't done very many myself but of those I have done some were drag engraved with a 90 deg diamond drag bit, some with a 120 deg carbide drag bit & a couple were carved 3D models with a tapered ball nose bit.
Keep meaning to have another go at it myself but other things keep coming up I am actually doing a job just now for a customer, not an engraved edgelit sign but it does use LED light strips, about 35 metres of it fed from 2 controllers

[dwilli9013]

Hi Chris and welcome to the addiction.
I too have run into the streaking issue. Cross hatch seems to be the going fix for me anyway. It adds time to the cut but eliminates the streaks. I have found that when the bit picks up and moves to another area when it returns to that area that is when the streak happens. It could be any manner of things. My thinking as that as the drag bit is cutting it is actually embedded to full depth when it picks up and leaves that spot. Then when it comes back to that spot it is starting in a new area and is not fulled seated in the material. I have messed around with spring setting a bit with my tools and it gets much better but I have never been able to completely eliminate it yet other than using the crosshatch option.
Now with a 1/64th tapered ball nose and a spindle speed of 8000 rpm I get a super clear finish in fact it is almost to clean. As the light is transferred best from the fractured surface. I found that when I flame polished my edges especially the edge recessed into the base my panels did not emit near the light. So now I generally hit the edge in the base with 220 grit to frost the edge and it lights up as expected. For other contoured edges I will use a card scraper to smooth out any machining marks.
My biggest recommendation would be "O" flute bits. I get mine from Amana but any supplier would work. When I am coutting or pocketing I slow down my spindle until I start seeing chips about the size of a babies fingernail. With my spindle running that slow you can actually hear any variation in the cut. Only problem I have ever had is if I bump the feed rate too much Acrylic will start to ball up on the end of your bit. Then that will lead to an ugly mess.
Warning to you these are extremely addicting.. So much so that I have rigged my table to light the panel as I cut. but that is only due to my obsession with watching the machine run once I start watching (especially when the spindle is off) it is very hard to look away. I find this same thing to be true for my 3d printers as well.
Enjoy and show us some of your panels I always love seeing them.

[Chris Hawks]

Thanks Dwayne. That is the exact same problem I am having, when it picks up a moves to a different spot or if it stays down it starts off good and then acts like it's digging deeper. I have done then hatch but not the cross hatch. i wished i could stop the outer profile line when doing a hatch or corss hatch in the "quick engrave toolpath". It's probably my machine but when it does a outer profile line it might be on it or maybe off of it. Like if I hatch a square and it puts the profile line around the square some of the lines may not be up next to it thats why I wanted to do a Pofile toolpass because you can tell it "not" to do a profile pass. But I will give the cross hatch a try and see if thats bettrer and I do have a tappered ball mill that I will try also.
Thanks

[Chris Hawks]

Well seems like the cross hatch is the ticket. I did all sorts of shapes and words for a trial run. When I engrave a square the lines for the outside profile are good but when I did for example a letter "H" the profile lines are not up next to the letter. I'm wondering if the profile line is where it wants to be but the hatch is not coming out to the profile line evenly. So if I was to tell the tool data base that it was a15 deg bit instead of a 90 deg bit I wonder if it would go out and meet the profile line. I think I'll try that right quick.

[Chris Hawks]

Well that didn't work either. I changed the 90deg to a 45deg in the toolpath. I did a outline of a "H" first then went back and crossed hatched the "H". While watching my machine engrave the "H" it would keep the cross hatch lines perfectly inside and up against my profile line but when it went to do it's last profile line it goes outside the first profile line. The thing is it does a square perfectly.

[dwilli9013]

Well that didn't work either. I changed the 90deg to a 45deg in the toolpath. I did a outline of a "H" first then went back and crossed hatched the "H". While watching my machine engrave the "H" it would keep the cross hatch lines perfectly inside and up against my profile line but when it went to do it's last profile line it goes outside the first profile line. The thing is it does a square perfectly.

Take a look at the endplay in your dragbit tube compared to the tip itself.

[Xxray]

You may have an issue of going too deep, which will cause any conical bit to obliterate details [and go outside of margins] the deeper you go.
You want a good scratch and not much more.

Also, make sure workpeice is perfectly level if it appears depth is not uniform.

[Chris Hawks]

Here are my settings that I'm using.

90deg diamond bit tool data base
dia 0.01
angle 15
line width .001
step over .005
50 inches per min

quick engrave tool path
depth .06
step over .005
hatch angle 45deg
cross hatch

[Xxray]

I was thinking vbit, my bad.

[Chris Hawks]

This was just a test to see if I could load a photo. Anyways here was the project that had light and dark areas. The right leg and left arm.

20180212_170426[1].jpg (9.21 KiB) Viewed 2205 times