Shenhui Laser Problems

[Brent Ramsay-Boyd]

Hi Shenhui Users

I have had my 1300 x 900 80W Reci Laser for about 4 months now, and I have to say I have not been terribly impressed.

Things started out ok, but things have steadily declined and my frustration levels are at an all time high, I am hoping that some of you have some useful advise that could help me turn this situation around.

When I first got the machine all seemed to be working fine.

I was able to cut 3mm Mdf at 35mm/s and 100% power, all cutting right through. 6mm MDF was 15mm/s and 100% power. I had values for other materials, but I need not list them all. Point is I am now cutting 3mm at 12mm/s and 100% power, and I am not always getting all the way through. Similar results with 6mm and other materials. I am having to cut everything at half the speed with no guarantee of a clean cut. I am unable to cut a whole job without having to repeat some part of it, wasting time and materials, very frustrating.

I have made sure the cutting table is level, made sure the materials are level, so that the laser does not go out of focus, I have made sure the optics are aligned and clean multiple times, I have made sure the laser is in focus, the focal lens is in the right way. I also made sure not to run my tube over 24mA, so that I do not reduce the tube life, (there are probably between 50 - 100 hours on the tube). Still I seem to be plagued with problems.

I am also having very inconsistent cutting on the table, the laser will cut one item fine, and then the item right next to it will not cut well at all. The laser power also seems to decrease significantly as it moves from left to right, this of course leads to a a lot of wasted time and material and a lot of frustration, I would be suprised if I am getting suitable cuts on half the table.

If anyone has any ideas on how to solve any of these problems, please let me know, I am desperate. Part of me wishes I could send the thing back.
I know that some of the difficulty may be from my inexperience, but surely there is something else wrong.

I have been in contact with my salesman and with Joy the technician, and I have scoured the forums looking for answers, but I feel like I am running out of options.

I have no problem with any of the staff from shenhui, if anything they have been nothing but helpful and accommodating, and I still believe the claims about the quality of there machines, but did I just end up with a lemon?

Again any help would be greatly appreciated.

I am trying to get a hold of a decent camera, so that I can photograph some of the problems I am talking about.

Regards

Brent

[matthew knott]

Dosent sound like your having much fun Brent, its unlikely you have a 'lemon' as the machines are so fundamentally simple and cheap to repair/fix you can just change the offending parts till its good. First things first you need to look at the obvious, have you checked the laser power output? or do you even have a way to check it? Without that its already and uphill battle. Do you have a spare tube or PSU, if so i would try a different tube, these things are made to a tight budget, they dont last forever and some last longer than others. Think of it like a bulb, some last years & some last days. The only other option you have is if you dont wont to swap parts out then try and find someone that services chinese lasers in your area, I would imagine they could have it up and running pretty quick.
Sounds like youve just been i bit unlucky but it happens, I Just go off the phone to a customer who has a brand new top of the range laser (best of the best) The tube failed in it at install so he had to wait a week for the engineer to fit a new one, now 3 weeks on the tube is playing up and wont engrave at 100% power but cuts perfectly so hes waiting for another new one. He paid $60K so it comes with great back up but hes still in the same boat as you!

[David Somers]

Brent,

Just to add to Matthew's comments. If you can't find a local repair shop that can help you and you need to diagnose this yourself, Matthew mentioned a laser power meter? Assuming your local tool rental shop doesn't have a dozen or so on hand (snort) I believe Laserbits still rents them. They will ship you one and you ship it back when you are done. The terms are shown in their web page. That might help in a pinch. Laser engraving/cutting shops in your area might have one they would be willing to loan you as well.

Dave

[Dave Sheldrake]

Hi Brent,

The working current of the 80 watt RECI is supposed to be 27mA and will not reduce life by running it at that (as a maximum),

Check your cooling, any more than 23 degrees C will reduce power and shorten life on the fatbody tubes (more so than over current)

Clean the output coupler (the lens on the end of the tube)

Check your tube connections to make sure you aren't leaking any power.

RECI are known to punch high for the first 3 months then drop back a bit but no where near as much as you are experiencing, 12mm PS at 100% is about what you would expect from a stable 40 watt glass tube.

Check your MDF supply as well, any damp will reduce cutting power by orders of magnitude.

Try running the 3mm MDF at 75% power and 15mm PS, sometimes more is less, as the tube stabilise the beams can start to scatter leading to more carbon and carbon sucks up IR like a sponge.

cheers

Dave

[Rich Harman]

I have had all the same issues as you describe. I would expect that alignment is the issue. The larger machines require more accurate alignment if you want to make use of the whole table.

When you have completed your alignment, put a piece of tape over the last mirror (the one right before the lens) and test the centering at all corners and midpoints of the table. Something I do to make this easier is to make my first test fire then use a sharpie to draw a cross centered over the dark spot. Then I can place another piece of tape over it and fire again at the next location. Real easy to tell that way if it is hitting the same spot. I'll keep refreshing with a sharpie and adding tape as necessary. If the spot drifts at all then you are not done with the alignment.

Chances are very good that your X axis (the gantry) is not exactly perpendicular to the Y axis, and your nozzle is probably not perfectly perpendicular to the table. These things don't seem to be very important to those who assemble the machine but they will affect your cutting.

Same for leveling the table. Check for level all over the table, not just the corners.

It takes patience to do this right so expect to take a few hours (at least) the first time that you do a serious alignment. By serious, I mean not something that is just good enough, but very nearly perfect. When you think it is perfect go and test it all again, something will be off.

I have found that my machine is performing better as time goes on. Probably not magic, I am pretty sure it is because each time I align I set a higher standard for myself.

[Rich Harman]

Clean the output coupler (the lens on the end of the tube)

Reci specifically states not to touch the output lens, or to use acetone. Before messing with that I would carefully verify that it actually needs attention. Screw that up and your tube is done for.

[Clark Pace]

Hi,

The gweike machine I run has power issues that were driving me crazy. I would align it then it would un align after a few cuts. I gave up and came back to the problem a few weeks later (have another laser). The problem ended up being a simple mirror was not in tight. So it would wobble just a little and my power would be in-consistant, and alignment would be off and on. Just a thought.

[Brent Ramsay-Boyd]

Thanks for all the input, I will give these suggestions a try this weekend. I also has found a laser cutter technician, so I will try get him in early next week.

I will keep you all updated with the progress.

[Brent Ramsay-Boyd]

So turn out as Dave suggested, if you want more power from you laser, you reduce the power. Does not make sense, but at least this has solved one of my problems. It is still not completely right, but at least I was able to finish the order I had. Hopefully some tweeking will get it back to where it was.

Can anyone supply me with sample photos of engraving they have done on a shenhui, I haven't been happy with mine since I got it, I would like something to compare against.

Thanks

[Dave Sheldrake]

Reci specifically states not to touch the output lens, or to use acetone. Before messing with that I would carefully verify that it actually needs attention. Screw that up and your tube is done for.

Indeed they do Rich, but I've seen more than a few tubes blow the output coupler because it has smog on it that gets hot and seperates the two lens's. In a sealed system the coupler isn't an issue, on a system where smoke and fumes can get to the tube it can become an issue quickly.

cheers

Dave

ps: as you said, never use acetone on any lens...IPA or de-ionised water for the coupler only.

[Clark Pace]

So turn out as Dave suggested, if you want more power from you laser, you reduce the power. Does not make sense, but at least this has solved one of my problems. It is still not completely right, but at least I was able to finish the order I had. Hopefully some tweeking will get it back to where it was.

Can anyone supply me with sample photos of engraving they have done on a shenhui, I haven't been happy with mine since I got it, I would like something to compare against.

Thanks

If you send me a file I will engrave it. Just let mw know what you have engraved on.

[Peter Odell]

Have you cleaned the mirrors I know mine will lose power if they are not clean