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Wolfster
23-01-2016, 09:19 PM
Hi,

A bit of a desperate plea for help I'm afraid... Does anyone know of any hobby laser support / setup people in Kent UK? I'm located in Dover Kent.

The issue I have is mirror alignment. After spending hours over a number of weeks I just can not seem to complete this simple task. Each of my many attempts has just ended up with me sobbing in the corner. I'm at the point where I need help and happy to pay for someone's time.

It's a Shenhui SH-350 (50W Chinese laser).

When I originally receved the machine it worked out of the box but after an hour or so of firing it stopped working. The vender sent me a new power supply and tube which I fitted (it turned out to be a faulty PSU) and the machine is firing fine again but I cannot nail the alignment.

I've watched a myriad of videos and read loads of articles around the subject and been though a number of rolls of masking tape but I just can get it right.

Many thanks,

Paul

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komatias
23-01-2016, 10:33 PM
Hi Paul,

bit out of the way for me to come have a look but I have the same machine as you, I think. Did my alignments recently again too to make sure it was good. What seem to be the issues that you are actually having? Is the spot on each mirror not central? do you have differing intensity/focus with travel?

I find that if I am not getting good results it is usually warped wood being cut or dirty lenses. May not be your case but do give the optics a clean.

so let us know what happens and I will try and help you.

Wolfster
24-01-2016, 04:15 PM
Hi,
Thanks for the reply.

To be honest I’m pretty sure it’s user error!
It’s difficult to get the laser tube central on the first mirror (to high) then I just can’t seem to get the beam parallel on the second mirror with at least 5mm or so movement at each extremity of Y axis travel.
Any advice would be appreciated.
Thanks

andy_con
24-01-2016, 06:27 PM
Ivery aligned a few lasers in my time ;-)

http://i989.photobucket.com/albums/af11/redcowboy/arctos_red_laser201_zps3mizluql.jpg

Wolfster
24-01-2016, 08:29 PM
Very impressive! I assume you don’t live near Dover ;) Unfortunately your picture serves to make me look even more inept!

andy_con
24-01-2016, 08:48 PM
Im in essex so three if not more hours away, sorry

Wolfster
24-01-2016, 09:31 PM
Im in essex so three if not more hours away, sorry

No problem, sorry to ask!

andy_con
24-01-2016, 09:45 PM
post some detailed close up photos, a picture speaks 1000 words

Wolfster
28-03-2016, 02:01 AM
Sorry for the delay, I've been having some work done to the house which took over my garage (aka workshop).

I spent another 4 hours or so trying to nail the alignment but to no avail. I have make some mdf laser tube mounts to get the laser tube better centred on the first mirror but still have a lot of movement as the laser travels. I have uploaded a video to youtube and attached pictures.

I must be doing something fundamentally wrong. I've not been able to use the laser for weeks now. :(

Link to video https://youtu.be/1ngpmipR4YM

180461804718048180491805018051

Robin Hewitt
28-03-2016, 12:02 PM
Tilt the first mirror up.

I had to print some new mounts for my laser tube, the originals were crap. I can probably find the .stl files but the only dry 3D printing plastic I have right now is marigold. Probably won't go with your Royal blue.

magicniner
28-03-2016, 07:14 PM
The beam angle is wrong, you are having to angle the laser to centre it on the mirror, this gives an alignment error which is proportional to the distance moved from the point where it is centred.
Rather than thinking of getting the laser pointing at a target think getting the laser running parallel to the movement of the target, it should be relatively simple geometry to work out,

- Nick

andy_con
29-03-2016, 01:25 PM
what I don't understand is, what are you trying to align the beam coming out of the tube with?also don't use any form of plastic printed mirror mounts, you may as well make them from bluetac

Robin Hewitt
29-03-2016, 04:01 PM
You align it with the travel of the X and Y axes.

magicniner
29-03-2016, 05:24 PM
also don't use any form of plastic printed mirror mounts, you may as well make them from bluetac

Provided the operating temperature adjacent to printed mounts is within limits they should be OK, what's wrong with ABS mounts?

andy_con
30-03-2016, 01:20 PM
Provided the operating temperature adjacent to printed mounts is within limits they should be OK, what's wrong with ABS mounts?

cos they aren't stable, ask anyone who works with lasers.

Robin Hewitt
30-03-2016, 01:32 PM
...and cheap Chinese mirror supports are? :hysterical:

magicniner
30-03-2016, 04:47 PM
I think it's a case of "horses for courses", you wouldn't use plastic mounts in most laboratory experiments or in most applications in industry but you'd likely have access to a machine shop and/or an enviable project budget ;-)

It's very easy to be sniffy about things that actually work but are to a lower engineering standard than you'd like if you've never had to work without the financial and technical means you are used to.

Why not make a set of mounts in good old fashioned Meccano?
Now there's a serious engineering material ;-)

- Nick