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Thread: Jig for glueing galvo mirrors?

  1. #1
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    Default Jig for glueing galvo mirrors?

    I'm not sure if I'm doing it right I tried it twice now which is glueing scanner mirrors with epoxy.. however I notice on projections I get wobble and its usually in one axis.. X axis.
    It's not a grounding issue I'm 100% sure so I'm assuming it is because I didn't glue my scanners perfectly. I should mention I'm using 5 minute epoxy which doesn't seem to be be the right thing to use.

    I read in a thread about the hanging upside down trick which for me I guess didn't seem to work even though I kept adjusting to get the mirror to be as straight as I possibly could get it.

    Does anyone have a jig for glueing scanner mirrors? I recall there being a 3D printable scanner jig for this but nobody really shared it publicly and it would be of great help.
    Last edited by masterpj; 06-27-2015 at 03:50.

  2. #2
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    Bill from pangolin tuned some dt scanners for me years ago which has mirror wobble.

    He ended up putting a tiny line of glue along the back of the mirror to strengthen it and stop the wobble
    Eat Sleep Lase Repeat

  3. #3
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    I know about the glueing method.. I'm not sure If its "really" caused by the mirror For one the mirror on this scanset was still on it and was used in combination with the other scanner and I didn't experience wobble until I broke it and had to replace it.. then again it's also a while since I've used these scanners.

    What is interesting is.. if I change the scanners wiring it will not change the direction of the wobble.. neither if I swap the scanners orientation of X and Y it seems so far.. I guess it's the fact I'm feeding the beam externally from another projector and using a vice to clamp down the scanner mount?

    I checked if grounding was a thing and wired a cable from the scanner block to the scanner amplifier heatsink.. dindn't make a difference. It's also not tuning related. When I reclamped the mouth diferently though it seems like the scanner wobble in the axis has gotten less but as I once had in the past the wobble is present depending on scanspeed and scanned image.. its just so weird...

  4. #4
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    ... I've CNC-milled a simple rig/holder to fix the mirrors in the right position, while the glue hardens, when glueing bigger mirrors on my first cheap chinese galvos.

    And 'atomized' the mirrors several times while experimenting with high power lasers, so this was a great help to repair them anew ;-)

    Viktor

  5. #5
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    Quote Originally Posted by VDX View Post
    ... I've CNC-milled a simple rig/holder to fix the mirrors in the right position, while the glue hardens, when glueing bigger mirrors on my first cheap chinese galvos.

    And 'atomized' the mirrors several times while experimenting with high power lasers, so this was a great help to repair them anew ;-)

    Viktor
    Do you have access to these CAD files still?

  6. #6
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    Ive used a jig as well, but it did not require complex machining. Firstly, in diagnosing the cause is it a rate related wobble? If a mirror is firmly attached, but out of balance and even not orthogonal to the shaft then only the position of the reflected beam, and when scanning the line, should be affected. If way far from orthogonal, then the scan range will be noticeably reduced, but a 1D rotation of the scanner motor should only be able to create a 1D scan and there should be no arcs or wobble. No matter how unbalanced, if scanning very slowly there should be no vibration. I am assuming your motors are tightly mounted.

    What I have done is to mill a slot out of the corner of a block of metal. The block should be tall enough that when sitting on the scanner block ( the other scanner has been removed for this installation) the horizontal surface of that slot is exactly the same height as the gluing surface on the motor shaft. The motor is adjusted in the scanner block so that the gluing surface is horizontal when the motor is de-energized and slid back so that the motor face does not prevent your gluing jig from sitting square against the flat surface of the scanner block. You may have to remove a small amount of material from the slot to allow the motor shaft to sit at the correct level as the mirror-supporting, horizontal surface of the slot as well as inboard sufficiently to allow more than 50% of the mirror's weight to be on this surface. This will prevent the mirror from tipping off while the glue is drying. Centering the mirror is done by sliding the slot in block until the vertical edge of the slot is 1/2 the mirror's width from the center line of the motor shaft.

  7. #7
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    Quote Originally Posted by JohnYayas View Post
    Which direction?
    No idea was a long time ago.

    There is a post on pl somewhere about it, but it's mega old
    Eat Sleep Lase Repeat

  8. #8
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    I almost never have luck with current araldite 5min epoxy.. usually becomes a bit "gummy" when cured...seems it needs EXACT 50% mixing and this is almost impossible to achieve.. in my experience mirrors tends to loose FF adjust when temp changes...this gummy characteristic could affect galvo performance as well?
    Anyway I always go with:
    http://www.allwaytech.com/catalog/in...roducts_id=419
    on mirrors, galvo, and of course when need good heat transfer... not cheap but pretty solid when cured
    Last edited by jors; 06-27-2015 at 08:58.

  9. #9
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    The trick to the 5 minute epoxy is to mix plenty of it... if you only try to mix enough to do a mirror it surely will not cure... i mix about a half dollar amount whether im gluing 1 mirror or ten. I use the loctite 5 minute epoxy from any hardware store.

    A jig is very helpful. From personal experence and using custom test patterns Bill made, we have found that the mirror not being axially aligned with the shaft even by 0.002" can cause problems in the projection in terms of horizontal/vertical skewed lines, and being off center excites resonances easily noticable in certain test patterns..

    Making a mirror mounting jig is certainly the way to go. That is how we mount all the mirrors on the C506 and Saturn scanners at Pangolin with very few and far between issues... it can take a while to get them set perfectly under the microscope depending on mirror size but once they are set, they're worth their weight in gold and we can mount 5-8 mirrors at a time with one batch of quick cure epoxy.
    Sincerely,
    Ryan Smith
    ScannerMAX Mechanical Engineer
    ryan {at} scannermax.com

  10. #10
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    Quote Originally Posted by rns0504 View Post
    The trick to the 5 minute epoxy is to mix plenty of it... if you only try to mix enough to do a mirror it surely will not cure... i mix about a half dollar amount whether im gluing 1 mirror or ten. I use the loctite 5 minute epoxy from any hardware store.

    A jig is very helpful. From personal experence and using custom test patterns Bill made, we have found that the mirror not being axially aligned with the shaft even by 0.002" can cause problems in the projection in terms of horizontal/vertical skewed lines, and being off center excites resonances easily noticable in certain test patterns..

    Making a mirror mounting jig is certainly the way to go. That is how we mount all the mirrors on the C506 and Saturn scanners at Pangolin with very few and far between issues... it can take a while to get them set perfectly under the microscope depending on mirror size but once they are set, they're worth their weight in gold and we can mount 5-8 mirrors at a time with one batch of quick cure epoxy.
    Would you have such a mount ? are they universal or made per scanner type?

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