View Full Version : Engraving on mirrored acrylic.

Callum Angus
06-28-2016, 6:39 PM
Good evening all.

Im looking for some help if you wouldn't mind. I've got an award to engrave onto and im having some trouble. When I am carving the letters into the piece I'm using the same settings I would it I was using wood... The trouble is the end product looks like melted plastic and not pretty if you know what I mean.

I have a redsail x700 with a 60w tube installed. Power set to 20 and speed at 200m/s... Is that the right settings for etching onto acrylic??

thank you

Mark Sipes
06-28-2016, 6:55 PM
Since you have a piece of scrap in your hands, this appears to be a training opportunity. Keep the power the same and increase the speed........ Start building a material profile for your machine. Make sure the beam is in focus..... change DPI setting and develop a feel on what your machine can accomplish at different setting. As materials change so do the setting.... a profile will get you closer to hitting the mark.

On my machine I would lower the Hz setting and increase the speed. I can hit my image a second time with the same setting or modified to get a deeper cut.


Bill George
06-28-2016, 7:00 PM
Vector cutting or carving, or rastering? If your rastering or engraving a image or text into acrylic you will need to lower the power or increase the speed. Get some scrap pieces to practice on before you do the "real" thing.

Clark Pace
06-28-2016, 7:43 PM
Vector cutting or carving, or rastering? If your rastering or engraving a image or text into acrylic you will need to lower the power or increase the speed. Get some scrap pieces to practice on before you do the "real" thing.

Also it's probably extruded acrylic so you won't get a frosted white finish. It will be more clear.

David Somers
06-28-2016, 8:53 PM

To add to Mark's suggestion. Go a step further and make a pattern of squares in corel so you can engrave or cut parts of the pattern at different settings. You are basically making a grid of speed settings on one axis and power settings on the other. Look up the recommended settings on your machine for a material and make that the middle speed and power setting for the grid and then bracket your settings around that. Doesnt have to be large. Just on some scrap. When you are done you now have a nice record of what each of the settings looks like so you can quickly choose the effect you want later on when you use that material again. If you were engraving maple for example and had already done a power and speed grid like I described you could pull it out and look to see what power and speed setting gave you the result you want. You can do the same thing with vector cutting, and with vector engraving. (using a vector drawing rather than a raster drawing for an engraving)

A caution with lasers. Dont rely on someone else's settings. Use them as a starting point for a test? Sure. But dont expect them to apply to your machine. These machines are touchy little devils and what works on one machine may not work on an identical machine. Better to test things and be sure, especially if you are committing time and $$ in materials.

Hope that helps!


Callum Angus
06-28-2016, 9:17 PM
Thank you so much guys!! All great ideas!

Im going to set up a test over the next few days.

one thing I must ask tho if y'all don't mind... I haven't aligned the laser from getting it out of the crate.. Will this affect the power of the laser. It is having trouble cutting through 3mm plywood that's all and I thought it would make short work of that.. Also I have the laser 15mm from the material I am cutting, is that the right length and do I need to reset the focus length each time i move the bed up and down??

sorry about all of the questions!!


Kev Williams
06-28-2016, 9:43 PM
If your wood was say, 1/2" thick and the acrylic you're working with is 1/8", and you HAVEN'T (re)focused the lens-- that could be the reason for your acrylic issue--

David Somers
06-28-2016, 9:55 PM

The laser has a very narrow depth of field to its focus. So yes, you do need to refocus anytime you change the height of the bed or the material. They should have given you a focus gauge to help with that. Basically it usually is a piece of acrylic cut into a rectangle. One side of the acrylic will be the correct distance to set between the underside of the lens tube and the surface of what you are working on. If you change lenses, or you change to a different focal length lens you will want to make a new gauge to go with it. Focus is critical with any laser.

Did they include directions on how to change the focus? Did they give you a gauge to help focus?
It is also not a bad idea to check the alignment of your mirrors. Odds are they are OK. But you never know. Doesnt take long to check and it gives you peace of mind.
Lastly, you may also want to check your table to be sure it is dead level with the XY axis of your laser. Getting your lens in focus is not helpful if the table is cattywumpus to the gantry. Hopefully they gave you directions for all those things?

If you think of it, you might add your laser (make model, power, size) to your signature in the forum. Then each time you post something that basic info is visible to us so we have a clue what your setup is. It can also be helpful if you add your location to your profile, which will then appear in the top right of each post you make. Then if you ask for a source for materials you wont have Mark and I suggesting you drive down to 1st Ave in Tacoma, WA for your source when you are in the Seychelles or some other far distant land. Unless you want to come to the Pacific Northwest for supplies of course!! Always happy to have visitors!!

Wilbur Harris
06-28-2016, 10:52 PM
Spend some time aligning the laser. Make sure the mirrors are clean while you're checking the alignment. Make a focus tool and use it every time....once aligned, you can cut a line on a slanted piece of wood to find the correct focus (see below).


Callum Angus
06-29-2016, 2:22 AM
That's great guys. Thank you so much.

Ive had a quick look at the mirrors and they look a little dirty so I'm going to give them a clean and align them when I get back later. Also there is a setting in my control panel to reset focus length.. Should I press that after everytime I move the bed up and down?

finallu in regards to the bed I don't think it is level as if I'm doing a large piece, say around 400mm the depth of the carve on the left looks great but the right looks a little shallow. The only way to adjust the bed is with a knob on then bottom right of the bed. I can't see any fine adjustments?

pictures to follow

Keith Downing
06-29-2016, 3:58 AM
This sounds like a focal issue most likely to me. It is very important that you correctly set the focal length from the lens to your workpiece every time. Even a few cm too high or low will result in problems.

Most lasers have an autofocus button, BUT if you've never calibrated that to begin with, it's likely worthless until done properly.

Callum Angus
06-29-2016, 4:53 AM
339952This is the only settings I can find on focus... Will this be what I need to change each time and is 2mm correct?

Callum Angus
06-29-2016, 4:55 AM
339953Also this is the bed lifter screw. But for some reason the picture has gone on upside down??

When end I turn this the other three turn at the same time but the bed isn't perfectly level... Does anyone know how to change this please

Bill George
06-29-2016, 7:25 AM
I think you need some time to learn your machine. Did it come with a Users or Owners manual?

Callum Angus
06-29-2016, 8:06 AM
No Bill. That's why I have turned to this forum for help

Bill George
06-29-2016, 9:18 AM
No Bill. That's why I have turned to this forum for help

This google Search brought up more than 10 pages (374 results) of info > redsail x700 site:www.sawmillcreek.org

Callum Angus
06-29-2016, 9:39 AM
That's Bill but that's not really a help.....

I've come to this forum to speak to real people that have been through what I'm going through.. I've already trawled through Google thank you very much.

David Somers
06-29-2016, 1:30 PM
Morning Callum,

Can you contact the company for manuals? That would be helpful for you in the long run. You could go to someone's web site like Rabbitlaserusa.com or bosslaser.com and grab their online instructions for aligning the mirrors, determining focus, leveling the table, etc. Basically all the maintenance features of a laser. They may not be exactly correct for your laser, but they will be close and a decent reference. Your manufacturer hopefully has something similar if you ask, though if you purchased direct from China it may not be terribly intelligible. When dealing with Chinese manuals I found it helps to have not only their translation, but to also have a simplified Chinese version of it. Then I will run the needed paragraphcs/sections of that through translators like Google or Babelfish and others and use several translations to make sense of it. The aggregate of those translations usually gets me what I need. My manufacturer will also gladly help, but given the time and date differences between us it is usually faster for me to do multiple translations.

Before you fuss with focus and the table you may as well check the alignment of the mirrors.
Here is a link to a video on aligning your mirrors.

Regarding Autofocus. I think most people here have found Autofocus is poor to useless. Though perhaps that is changing over time. I manually focus myself, and even the manufacturer of my laser said don't bother with auto. A lasers focus has a very narrow depth of field so you have only a VERY short distance above and below the focal point that is functional unless you are after some special effect. When you take the time to determine the actual focal point and make your own gauge for that you are guaranteed to be in focus, and quickly, for any instance you need.
The actual process of focusing involves knowing where the focal point is for that particular lens. While the lens may be listed as a 50mm lens, or some other number, that does not mean it is accurate so you are usually better determining the focal point yourself. Consider it one of the setup processes you need to go through.
Here is a link to a thread on this forum that goes through determining the focal point for a particular lens/tube combination. When I say tube I am referring to the tube that holds the lens, not the laser tube itself.


Now....once you know the actual distance needed between the underside of your lens tubes cone and the object you are cutting/engraving, you need to make a little gauge or spacer that is exactly that distance. Use a little piece of acrylic and cut it so one dimension is that measure. Then you just set it between the object and the lens tube and set things so the underside of the lens tube just touches the acrylic. Voila! Quick and easy.

Please forgive me if I am being too basic here, but I dont know how much you know at this point. But other than your autofocus you have two methods of focusing. You can raise and lower the table, or you can extend or contract the lens tube. The table is a gross movement so use it to get things approximate. The lens tube is for finer adjustment. Typically, a lens tube has a knurled ring where the tube that holds the lens slides into the tube attached to the mirror housing above it. You loosen that ring, slide the lower tube up or down so it just touches the acrylic spacer and then finger tighten the ring. Done.

If you ever buy a new lens to replace yours, or if you buy a new lens of a different focal length repeat this process and determine the correct focal length distance and make a new gauge or spacer. I have two 50mm lenses and they have slightly different focal lengths. Significantly different. So I took the time to make a gauge for each. If I ever toast my 1st lens I am ready to replace it with the second and have a focal gauge ready to go. The same is true with my other focal length lenses. For what it is worth, I have a dedicated tube for each of my different focal length lenses so I dont have to fuss with removing the lens if I want to change. They ran about $30 per tube so it was not that much. Perhaps more important if I were a production shop?? But I still like being set up this way.

Regarding your table. I cant tell from your photo but most tables have a base that a honeycomb top rests on, or perhaps you also have knife blade slats and they fit into that base and the honeycomb rests on those. The 4 threaded rods you mention are likely tied to the motor that raises and lowers the table and that is why when you turn one rod they all turn. You wont use those to adjust the table. In my case, I have both knife slats and a honeycomb. I probably got a bit anal about this and first took the time to adjust all the knife slats so their tops were level with the XY axis of the gantry. It is the gantry you are concerned with since that is what is moving your lens around. I put the far left slat into its slot. I moved the gantry over it and used an inside caliper to measure the distant from the underside of the gantry to the top of the slat at the back of the unit. Then moved the gantry to the front of the unit and used the caliper to adjust that end of the same blade so it was the same distance to the gantry. Then I moved the gantry to the far right of the bed and did the same thing with that blade, using the caliper setting from the left side. Now my left and right blades were level with each other and with the gantry. Then I put a known good straight edge across those at the back side of those two blades and adjusted all the blades in between the left and right sides until they just touch the lstraightedge on the back. I moved the gantry to the front of the machine and repeated this with the fronts of all those "interior" blades. Then I rechecked that to be sure I was OK. All done. I also took the time to put a drop of locktite on the threads of the adjusting screws of the knife blades so they would not wander over time. Nail polish works well for this too. Now when I set my honeycomb on top of the knife edge it is level with the gantry as well. In a fit of analness I also took the time to be sure it really was level and added a few shims to the underside of the honeycomb to correct it since mine was far from square on any measure. Then I also took time to drill through the honeycomb frame and into my table support and threaded the holes in the table. Then when I put my honeycomb on I can screw it in place securely so table vibration (or me being careless) doesnt move it accidentally. Once that was done I lay some masking tape on the back and front of the honeycomb table and used the laser to engrave a light line across the back edge of the table onto the tape. Now I could see that axis clearly. I used a cheap steel rule (any metal would do. I just happened to have some cheap steel rules around) and secured that down to the honeycomb along that engraved line. Now I had an edge guide for the back edge of the table. I did the same thing with the side of the honeycomb and glued a steel rule down on that edge. Now I had an edge guide at right angles to the back edge and had a way to quickly align a workpiece to the X and Y axis of the gantry. It made repeat setups much easier and allowed me to set an accurate origin point for the laser. And because my knife edges were fixed and level now, and my honeycomb was screwed down and its position quickly and accurately repeatable when I removed it to clean or use the knife edges those edge guides remained useable and accurate. And....in yet another fit of analness I used some acrylic to make a spacer so I would have a guide that placed my rotary onto the honeycomb accurately in the same position anytime I wanted. Now when I put that in place I know it is in line with my X and Y gantry axis without any question or fuss. That space looks pretty much like an oversized framing square. I lay that so it is against my steel edge guides. Then I lay my rotary frame into that spacer and I am done.

I know that sounds like a lot of work. I have a bit of a wood working background though and I HATE having things on a machine not be square and easily repeatable. This was also interesting. I asked my sales rep why chinese machines dont bother with this? It took a while for them to understand why I cared. They understood what I did right away but couldnt understand why. Turns out they just use overside material in the laser and cut it as needed and throw the waste away. No problem. No need for edge guides, not need for accurate repeatablity. Cutting an 8x10 something? Put in an 11x14 and laze away! I just hate working that way and took the time to make things solid and repeatable. I sleep much better at night and treat children and small animals with more kindness as a result.

Apologies for such a long winded response. I hope this helps you get going. And feel very free to chuckle ruefully and shake your head at my analness! <grin> Also....feel free to PM me if you need more details or want to ask questions off the main forum. Though to be honest....asking on the forum is actually pretty helpful to everyone. Someone else likely is having the same issue somewhere.

PS.....I have to get going on other stuff so I dont know how often I can check the forum today to see if you have questions. Apologies if you have questions and I am slow to respond.

Bert Kemp
06-29-2016, 4:23 PM
I'm going to mention again Please Post your equipment in your signature so we don't have to look all over the thread to see what were dealing with here:D Your telling us you can't cut 3mm ply with out telling us what your trying to cut it with is useless to us.

Thank you so much guys!! All great ideas!

Im going to set up a test over the next few days.

one thing I must ask tho if y'all don't mind... I haven't aligned the laser from getting it out of the crate.. Will this affect the power of the laser. It is having trouble cutting through 3mm plywood that's all and I thought it would make short work of that.. Also I have the laser 15mm from the material I am cutting, is that the right length and do I need to reset the focus length each time i move the bed up and down??

sorry about all of the questions!!


David Somers
06-29-2016, 4:30 PM
Callum....to expand on Berts suggestion...if you look in the upper right of the main forum page you will see an option for settings to the right of your name. Click on that. Then on the left edge look for edit signature. You can put your machine type and any other information you want repeated in there and it will show at the bottom of every message you post. Thanks for updating your location by the way. That is also helpful to folks. Even simply knowing the country is useful when we suggest sources.



Callum Angus
07-03-2016, 6:50 AM
Hi Dave.

sory for the late reply. I'm on my honeymoon at the moment and wifi is terrible.!!

I just have have to say what a gentleman and a legend you are for taking the time to write all of that for me. I appreciate it very much!!

I will have a chance to reply once I'm back in the UK next week.

again thank you so much!

Callum Angus
07-04-2016, 4:29 PM
I'm in Spain on honeymoon at the moment and can only get it on my phone. I'll try to do it now

Callum Angus
07-05-2016, 7:37 AM
I think I've done it

Callum Angus
07-09-2016, 4:39 AM
Hi David.

Ive just got back from honeymoon so I know have Internet...

ive tried to watch the video on YouTube that you sent me the link too but I can't watch it as it is a private video???

Bill George
08-27-2016, 1:40 PM
I think I've done it

This really means what?

Since you posted on a Public Forum you will expect to get replies back the same way. Bert was just asking.