Laserscript user forum

Hello All,

Today, at last, I was ready for full-on production tests with my 60 watt 3060. I've done a few minutes of speed and power testing previously, but no serious cutting work.

Five minutes in, whammo! The second mirror (that moves along the Y-Axis) overheats and pops! I'm out of action. Frustrating.

During testing at HPC's factory the first mirror popped - and Chris replaced it - so this is the second mirror that's failed in no more than 15 minutes of cutting.

Any thoughts? are there different mirrors for 40 watt and 60 watt tubes? Has my machine come with a bad set of mirrors? (In which case the third mirror should be ready to pop at any moment...)

All the best,

James

Hi James,

Mirrors are usually one of four types,

Gold Coated Basic Glass (K2)
Gold Coated Silicon Glass (Si)
Molybdenum (Mo)
Copper (Cu)

afaik HPC don't use K2, Si are good to 60-80 watts, Cu will cope with 150 easily and Mo will go to 600 watts+

Mirrors can have flaws but it's rare, the main thing that causes issues is dirt on the surface getting hot and cracking them. Also pays to be sure they are not too tight in the holders as they need a tiny amount of room to expand, NOT loose so they move but not murdered up tight with a long tool bar either.

cheers

Dave

Thanks Dave,

Well, by their lack of answer on the phone, it looks like HPC are closed for the duration. Would have been nice of them to tell us their closed dates on the website and/or their answerphone message... :-/

Meanwhile I want to get cutting! Any idea where I can get a couple of suitable mirrors pronto? (Yes, I don't trust the third mirror in my machine now - if it's anything like the last two, it'll last minutes...)

I'm in Sheffield - will travel (within reason!)

I'm gathering that the mirrors for a 3060 are 20mm diameter (?) 3mm thickness (?) and preferably Mo or Cu type, or Si at a push?

Thanks!

James

Well, I have got nowt here. I only have a spare 25mm MO mirror. Think I gave my spares to the person who bought my LS3020. Sorry!

I have spares but I'm in Devon - I think a bit far?

You can make them out of an old hard drive disk apparently - not recommended but maybe good enough to play with

Best
Dave

Thanks for the fast responses, Philly Dee & Dave,

Agreed - Devon is a bit too far to travel!

I'm not 100% sure of the diameter, but I *think* it's 20mm not 25mm on a 3060.

Just to clarify, I take the mirror out by unscrewing the cross-head screws at the front (i.e. illuminated) side? (See the picture below).

Dave - I'm soooo tempted to try the "old hard drive" temporary fix, if only just to say I have! In for a penny, eh?

Fortunately, I think I may have an alternative supplier in the Sheffield area who can help me out at short notice - so perhaps good sense will prevail.

All the best,

James

Hi James,

noooooooo the circular disk should unscrew to remove the mirror, the screws hold the retainer springs. (I think, it's a long time since I played with any of the smaller machines)

cheers

Dave

Dave is right - the ring unscrews (normal thread). They should not be too tight - same with the lens holder and gold side facing the beam

They are 20mm on the 3060

Cheers
Dave

Thanks guys!

Actually I figured this out just before you answered me. Okay, so now I've removed it, I can see quite clearly, the mirror is 20mm diameter, 3mm thick, and has the mirrored side facing the beam. Looks correct to me - and the mirror is quite clean - which suggests to me that maybe this laser was fitted with a bad batch of mirrors - unless they had some kind of mysterious, invisible coating on.

Now the challenge is to get one in Sheffield, within the next couple of hours! Otherwise I feel an experiment coming on...

Cheers,

James

Hmmm, okay, here's where things get a little frustrating. If I were HPC, I'd start to worry about my mirror supplies.

I noticed that the beam wasn't central on the mirror. This shouldn't be a problem - mirrors reflect all over! But it did give me an opportunity to remove, and clean the cracked mirror, rotate it in its housing, and do another test cut using a clear area of the cracked remains of the mirror. This I did, realigned the mirror, and started another test at 95% power. Within 5 minutes the surface was glowing red again - if I hadn't stopped the laser it'd have cracked. The mirrored surface was burnt. Clearly the mirrors that I was supplied with just aren't standing up to the power of the beam.

Annoying! Well, I'm off to Rotherham to try for a replacement.

Cheers,

James