Weird issue engraving glass

[Josh Ledger]

Hey everyone, I have been testing out engraving glass and using my rotary attachment and I thought I was getting pretty good results:
20160223_192345.jpg

(Sorry for the dark lighting, it was the only way I could get any detail of the engraving in the photo).

I wash one of the glasses like a normal glass (dish soap and a sponge with a green scrubber side) and after drying and everything it looks like this: 20160223_192223.jpg

It looks and feels as though some of the glass came loose or something during washing. I then used some steel wool but that only worsened the effect.

I am engraving with my china 500x300 "50w" ebay machine at 300mm/sec. 45% power and using my rotary attachment (which I will be figuring out how to get that to rotate the proper distance for the correct image size when engraving).

Any advice on how to fix the issue with the glass? Thanks in advance!

[Keith Winter]

Pretty common issue with glass you're not alone. Looks great until you wash and scrub it, that's when the fractured glass flakes off which is what you're seeing.

What size lens are you using, and how many passes?

Have you tried various settings such as a lower power to see if it works? You might also try a smaller lens size.

Hey everyone, I have been testing out engraving glass and using my rotary attachment and I thought I was getting pretty good results:
20160223_192345.jpg

(Sorry for the dark lighting, it was the only way I could get any detail of the engraving in the photo).

I wash one of the glasses like a normal glass (dish soap and a sponge with a green scrubber side) and after drying and everything it looks like this: 20160223_192223.jpg

It looks and feels as though some of the glass came loose or something during washing. I then used some steel wool but that only worsened the effect.

I am engraving with my china 500x300 "50w" ebay machine at 300mm/sec. 45% power and using my rotary attachment (which I will be figuring out how to get that to rotate the proper distance for the correct image size when engraving).

Any advice on how to fix the issue with the glass? Thanks in advance!

[Josh Ledger]

I'm using the lens that came with the machine (sorry, I don't know what size it is). I did just 1 pass. I can try lower power and see if that helps the issue. What size lens would be considered good for glass?

[Keith Winter]

I'm using the lens that came with the machine (sorry, I don't know what size it is). I did just 1 pass. I can try lower power and see if that helps the issue. What size lens would be considered good for glass?

On a US machine you'd want a 2" or less. Depends on the machine if it's Chinese, but some call it an HR head. I think the Hr head uses better optics than the standard 2" on Chinese machines. Chinese optics can be crap so if you're using whatever came with the machine that might be part of the flaking issue as well, if the beam isn't aimed very precisely due to poor focus (which you can control) or imprecise optics it will cause more flaking. As will excessive heat. Keep in mind though no matter the quality of the lens, all glass will flake some over time. With the right settings you can make it flake less though. Bill is the expert on here, best glass I've ever seen. Maybe if he sees your posts he'll chime in, or try search around on the forum. Let us know how it goes!

[Josh Ledger]

Thanks for the tips! I'll experiment a bit more and see if I can reduce the flaking.

[Chris J Anderson]

Also try a different type of 'el cheap' glass, you might be surprised at the difference in the engraving of different glass, with the same settings...

[Josh Ledger]

I'm using cheap glasses that I got at walmart. I think I'm going to adjust my image to be grey instead of black so that my "dots" are spaced out more and see how that goes. I've read on here and elsewhere that it is recommended for this type of issue. We'll see how it goes and I'll report back to hopefully help someone one else out who may run into this issue.

[Chris DeGerolamo]

Change to gray....likely will solve the problem, or at least satisfy you for the interim

[Keith Sherwin]

Josh,
If you are using RDWorks, there are at least three methods of getting the correct "linear" distance on your rotary. I use the % reduction on the Y-Axis as it seemed easiest to me. Here is a video - https://www.youtube.com/watch?v=sIlXSZhgbe4 Look @ ~ 9:00 Minutes for the mathematical (One Time) Calculation. Also read the comments below the video for another method. In my case it worked out to 43.7% reduction. on the Y-Axis. For my Dollar Store Wine Glasses, I do like you do, for the first cleaning pass and then I run them all through the dishwasher.

[Josh Ledger]

Keith are you talking about how to improve the issue with accurate sizing of the image on the rotary or how to help fix the flaking issue? I'm open to ideas on both topics as for the rotary, I was going to change the vendor settings like I saw in a video. Thanks in advance and thanks for all the suggestions! I'm hoping to run some more tests tonight

[Keith Winter]

I'm talking about the flaking the Grey will help too

[Josh Ledger]

Thanks Keith! I'm surprised I missed that video, I thought I'd watched almost all of his videos haha

[Bill Cunningham]

In my experience, glass flaking is usually caused by too much power. Particularly when using a bold heavy font. Throttle it back a bit, and or speed it up. Give it a good coat of thick heavy dish soap to help cushion the impact of the beam, and control the fracture. With a American machine 40% speed and 80% power works OK with my 40 watt(+-) machine