Unsatifactory Laser Engraving (Shenhui Laser)

[Brent Ramsay-Boyd]

Hi All

I have had my Shenhui 80W Reci Laser for a few moths now, and cannot seem to get my laser engraving to a satisfactory level.

When I engrave, I cannot seem to achieve the crisp detailed work that I have seen produced on other lasers, could this be a downfall of having a chinese machine, or am I doing something wrong, I am hoping that someone with a Shenhui could chime in and help guide me. The edges of the engraving seem to slope inwards instead of having a well defined edge, and the engraved surface has a very uneven and undulating texture. I will try to get a decent camera to get photo's of what I mean, but at the moment all I have is my phone camera and I cannot get any decent pictures.

At the moment I am engraving mdf, and I know it may not be the best material for engraving, but I have seen much better engraving on mdf before, so I know a better finish is possible. I am using a 40mm lens at 25 power and 300mm/s speed (Although I am not sure the head is actually moving that quickly). I have tried to adjust the interval setting but it does not seem to help.

I am just starting out with my own business and I would hate to supply my customers with sub standard work. Any help would be greatly appreciated.

Thanks

Brent

[Rodne Gold]

Without pics its difficult to say , invest in a cheap printers loupe or a magnifying glass (5x or so) to see exactly whats happening , a loupe is a must for any laser engraver , it is an invaluable diagnostic tool.

[Travis Wizniuk]

Hhmm that doesn't sound right.. Sounds like you are not focused correctly..

Also have to adjusted the SCAN GAP in Lasercut? I find is should be 0.055 to get nice crisp engraves..

[Walt Langhans]

Yeah.. where to start...

To begin with.. I have the same tube and a Shenhui as well, and work primarily with MDF.

MDF sucks for engraving. I used the same file with the same machine set up and had 2 VERY different results and the only thing that changed was the the MDF. No idea but I'm assuming it has something to do with inconstancy in the way MDF is made.

Your speed is WAY too high, I if you want crispness on MDF (well as crisp as you can get it) I don't go over 150ms.

And it also sound like you could be a bit out of focus or alignment.

The other issue is your 40mm lense, if you want really detailed work the smaller the dot the better.

BUT like Rodney said.. we need pic for a proper diagnosis and this advice is based on my 'best guess"

[Dee Gallo]

Hi Brent, welcome to the Creek! I cannot help you with your laser since I don't have your make, but there is a sticky at the top of the Engraver's Forum for tips and tricks on Chinese lasers... you might want to read those posts for general knowledge.

I'm hoping you will get yourself to a better place soon, the help already offered should start you on your way. These guys know what they are talking about.

cheers, dee

[Rich Harman]

This is something I engraved on MDF and posted about it a couple years ago. I don't remember the settings exactly but it was probably around 300 to 400 mm/sec at full power using a 65mm lens. My version is lying on top of the sample that Epilog sends out to prospective customers. The size is about 2" across.

AztecCloseup.jpg

[Brent Ramsay-Boyd]

Thanks for the replies, I will try to get some decent photo's and post them as soon as I can. I am also going to try some different materials to see if it is just poor quality MDF. While testing I have come into a second problem, I have noticed that the power from my laser has dropped, I have only got about 20 hours or so on the laser so I don't think it is the tube, but where I was cutting 3mm mdf at 35 speed and 100 power, it is now not cutting through. Is it normal for a new tube to loss power so quickly. The reci site states that for optimal tube life to keep the amps under 25mA, I have set it a bit lower that that, but this is only when it is running continuosly, between cut lines when the laser pulses it jump to approx 40mA for a split second, have I set it correctly, or should I be tuning it down?

I did have a problem the other day when I auto adjusted, the table bed crashed into the head and when I stopped it and the head tried to return to the origin and messed up my honeycomb table a bit. A very terrifying experience but all seems to be ok. I think this may have messed up my focus etc.

[Brent Ramsay-Boyd]

Is scan gap the same as interval?

[John Bion]

I did have a problem the other day when I auto adjusted, the table bed crashed into the head and when I stopped it and the head tried to return to the origin and messed up my honeycomb table a bit. A very terrifying experience but all seems to be ok. I think this may have messed up my focus etc.

Hi Brent,

I do not have Shenhui so I will let others comment on your software settings, however I would Strongly recommend you get rid of autofocus, this is nothing but trouble. It is very easy and quick to focus manualy. I would check for right angle alignment between the head and carriage after a crash like that.
MDF is very dirty material to cut, have you checked the cleanliness of your optics/mirrors? Is the end of your cone almost blocked with residue? MDF also jams up the autofocus very quickly.
Pictures definitely needed.
Kind Regards, John

[Brent Ramsay-Boyd]

Hi John thanks for the advise.

I have decided as you suggested not yo use the autofocus any longer. My optics are clean, and there is no residue on the nozzle. How do I check for right angle alignment?

Regards

Brent

[Khalid Nazim]

Get a carpenter's square to check if your laser head is perpendicular to the laser bed. And like the other shenhui owners said, ditch the autofocus. I had a similar accidend due to autofocus and had removed it afterwards. I dont miss it at all.

Regards
KN

[John Bion]

Get a carpenter's square to check if your laser head is perpendicular to the laser bed. And like the other shenhui owners said, ditch the autofocus. I had a similar accidend due to autofocus and had removed it afterwards. I dont miss it at all.

Regards
KN

as Khalid said.

Regards, John

[Travis Wizniuk]

I have a G.Weike with Lasercut software.. I just assumed the Shenhui used the same software..

If so, the Scangap can be found in the same location where you set the power and speed. Anything over about 0.065 will give super crappy results (you can actually see the individual laser lines).

[Brent Ramsay-Boyd]

I see, it is probably the same as the interval setting in my software. Will give it a try.

[Brent Ramsay-Boyd]

I have check for that the laser head is still perpendicular, and it seems to be ok. All the optics are clean and aligned, but still I am low on power. Any Suggestions?