LaserUser.com Forum (formerly RDWorksLab)

Gene Uselman wrote: Tue Apr 06, 2021 All controllers do the same thing and mostly have the same functions in them but they are called by different names and even if they are the same name, may do different things... so be aware.

Yes I am aware of this. However, aren't some things "constant" among different controllers, things like engraving acceleration on the X axis which does the engraving?

Gene Uselman wrote: Tue Apr 06, 2021 RF lasers are quite different from CO2 lasers- again they do the same thing but differently. They can fire much faster-
Russ has explored some of the differences on his video channel.

By de-focusing the beam it will lose definition- a larger spot engraved. First you engrave in focus to get nice sharp edges and then de-focus and run the same file over it again to level the background field.

Even so, wouldn't that only show up on the edges of the, say letters that are being engraved? I am also running it at a pretty slow speed (100-150 mm/s). Trotec also sells glass tube equipped machines perfectly suitable for use in rubber engraving. I have not watched Russ' videos on his RF modified china laser, however, so I don't know much about them. So I could be mistaken.

Finally, for a second pass, apart from needing to adjust my settings accordingly so I don't over engrave and remove too much material, I would have to find a way to secure the rubber on the bed, since I am guessing I would have to remove the residual dust that is produced so it won't fuse on the surface. I do not think that this is a feasible solution - somehow it is possible to get the engraved surface to look good, like I said, it even happened to me as well! I just don't get why the engraved surface to the left and right of a line of text would sit slightly higher than the surface that has been fully engraved, just like in one of the first photos I posted with the grey rubber. This can't be my DPI setting, as it happens ONLY where there is a spot in a scan line that material isn't being removed. This could be due to the ramp effect? I am not sure.

Gene Uselman wrote: Tue Apr 06, 2021 The eye-loupe must be quite powerful [over here our loupes are usually 1 inch square- I assume your is metric?] and the lines are quite far apart compared to the kerf or burnt lines. The kerf on my machine is about .5mm and your spacing appears to be 1.5 times the kerf- what is your scan interval?

Did you calculate the kerf based on my assumption of the x magnification level of the loupe? If that was the case, it's honestly just a guestimtion at best. Like I said, this loupe came with an offset printing press, needless to say the packaging or whatever might indicate how much it magnifies is long gone. Yes my loupe is almost certainly metric.

This is my test pattern for the reverse scan interval. It is set at 0.5mm scan gap, so I can distinguish the individual scan lines. I honestly don't know how large my kerf is - I am using a 1.5" lens focused on the surface of the material (Rowmark laminated plastic).

Sorry if my post is not very coherent - I had lots of troubles with some other machines today and I hope I am not spewing nonsense right now.

RF and CO2 lasers are 'triggered' completely differently, the way the requested power is generated is a whole different system- which could easily give different engraving results. Russ gets way into the theory and it is hard to stay away sometimes but he make it make sense.

Have you tried a second scan after de-focusing? We are experimenting with everything we do on the laser. It is a integral part of learning about the machines.

Just adding my 2 cents from what I saw of russ' videos. When he had a 'curtaining' effect, I think he looked into the belt between motors and also a lighter head. Something with less "stretch" and his head that's acrylic and light. IDK if that helps, but one way to check is to run it slow and under low power to simulate your normal setting, but without any 'wobble' from the head moving or the belt stretching tiny amounts.

Gene Uselman wrote: Wed Apr 07, 2021 RF and CO2 lasers are 'triggered' completely differently, the way the requested power is generated is a whole different system- which could easily give different engraving results. Russ gets way into the theory and it is hard to stay away sometimes but he make it make sense.

Have you tried a second scan after de-focusing? We are experimenting with everything we do on the laser. It is a integral part of learning about the machines.

I only used a 2nd pass in my very early days a couple of months ago. Adjusting the speed/power and using a higher DPI setting basically makes running a 2nd pass redundant and I'd say that it's pretty important to clean the rubber dust in between passes, and then I'd have to clamp down the material somehow. The usual variant of laser rubber is 2.3mm thick, and for a good impression, you need your stamp to be around 1.1 mm deep. Removing too much material can have negative effects on the stamp quality.

There is a 5 mm variant but it is used for very large stamps and it costs triple the price of the usual stuff. This does require multiple passes in order to get a deeper engraving, since larger stamps need it for better imprint quality.

I am honestly getting really good results for the most part right now after re-doing my reverse scan offset adj., my main concern right now is the wobbly lines. My X axis linear rail, when moving it by hand, binds a bit at the far right. I guess this has to do with the grease that the rails where covered with, I knew I should remove it but wasn't very thorough and did a quick wipe on the rails because I thought it wasn't that important and it's grease after all, why would it make it harder for the rails to move?

I will take them apart tomorrow, clean them and lubricate them with a light-ish synthetic oil, see what happens. It's not like I have anything else to try.

Joseph Leavell wrote: Thu Apr 08, 2021 Just adding my 2 cents from what I saw of russ' videos. When he had a 'curtaining' effect, I think he looked into the belt between motors and also a lighter head. Something with less "stretch" and his head that's acrylic and light. IDK if that helps, but one way to check is to run it slow and under low power to simulate your normal setting, but without any 'wobble' from the head moving or the belt stretching tiny amounts.

Yes, I remember. I think he also added a couple of pulleys in order to install the belt the other way around so the teeth on the belt wouldn't create that pattern. Unfortunately, while a similar effect shows up on my machine, the raised part of the "curtains" happens to the right and to the left of a line of text and then in-between the lines of text, the lower, normal engraving is present.