Broken Scanner Mirror

I bought some DT-40W scanners, today. I went and picked them up. I may have been careless, because when I got home, the mirror on the Y scanner is very loose, and would come off if I pulled on it with tweezers.

Can this be repaired very easily?
Is it a precision thing?
Can I do it?
Or must I send my scanner off to be repaired?

I am saddened with my newly acquired item. :(
If anyone has some advice, I would welcome some right now.

http://i1290.photobucket.com/albums/...psa208df30.jpg
http://i1290.photobucket.com/albums/...psa1e585ff.jpg
http://i1290.photobucket.com/albums/...ps235a913e.jpg

It may be hard to tell from the photo, but she is broken across the bottom of the mirror where it meats the shaft.

... shortly after taking the photos, the mirror done fell off her shaft in exhaustion.

From what I've heard it involves gluing the mirror as centered as possible, followed by a re-tune of the amp. I'd like to know myself just what's involved as I have a set of dt40's with a broken mirror I've been meaning to get up and running.

Clamp a hemostat on the shaft as close to the bearing as possible. Using a HOT soldering iron, quickly heat the remaining portion of the galvo shaft near the top. Your goal is to just soften the epoxy without cooking the oil out of the bearing. Sweep the remaining mirror out with a x-acto blade, dental tool, or eyeglass screwdriver as quickly as possible. This is tricky, but there is no easy way to remove the remaining glass out of the slot in the shaft.

Make a support jig of some sort to hold the mirror precisely as the epoxy will move the mirror somewhat when hardening. Avoid fast five minute epoxy, as it will pull the mirror around like crazy compared to a slow cure.

The trick is getting the right mirror and not damaging sides of the slot in the shaft. The rest is easy.

You'll probably need to calibrate the board, I'll post a link to a galvo tuning instruction in the morning.

Steve

Quote:

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Originally Posted by mixedgas

...Make a support jig..

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..Or send em down to me, and I can help ya out in a jif.. :cool:

Attachment 38376

IIRC, both of those mirs are the same-length, yes? If so, what I would recommend doing is, once the snapped-piece is out (..and, yes, I am happy to 'gut the fish' for ya.. :) we 'snip' it, to shorten it, just a tad, and clip the 'corner-chamfers', to match.. then, designate this as the 'X' (since it does not need nearly as-much 'span' as the Y..), and retune both amps, for the 'swap'...(..yes, I have done this with 6800 Y's in an emergency, and it works fine, just leaves you with a bit less 'scan-angle'... in this-case, you'd be fine, since the 'unbroked' one, can still be used as the Y...)

..Or ya can just buy a new mir, glue it up we the P'Fesser outlined, and call it a banana. :)

fwiw.. :cool:
j

Those jigs are mighty nice. Would you care to lease the longer Y jig to me for a week? ;)

Also, I enjoy your style of writing.

hey ps -

Quote:

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Originally Posted by pschlosser

Those jigs are mighty nice. Would you care to lease the longer Y jig to me for a week?

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Well, I'd not-charge you, but.. here's the only deale-o - a) I (actually) have 5 sets of glue-ups I am doing in the next week-ish, with them, and b) I would only send them out, if you were willing to commit to 'if you break, you buy' (translation: pay the cost to machine a new one, since these are not available, 'OTS', from anywhere I know-of, and... pretty-sure these are the last set on the planet.. :) So, those-be my 'terms for loanage'.. :p Lemme know...

PS - If you've never 'snipped' a galvo mir, w/o breaking it, I suggest not 'losing yer virginity' on this-one.. :) You need a very-specific type of wire-snip, and, a fair-bit of 'practice' (aka - destroyed mirs >_< ) to nail it on the first try - especially when it must be your only-try cuz ya've only got one 'try'.. :p So...

Quote:

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Originally Posted by pschlosser

Also, I enjoy your style of writing.

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heh, you mean you don't *mind* my 175-different STYLES of 'over-punctuating' / butchering posts??? *retardo ..I know, I know.. I need to see a Doctor, for sure.. :p

j

Bonjour, Greetings from Camp Grenada*, aka Quebec City..

Link as promised: http://www.skywise711.com/lasers/scanner/scanner.html
Other link: http://lasershowparts.com/files/Arti...20Tutorial.pdf

* Google the term.

I second Jon's suggestion on reuse and retune, although I prefer diamond tipped scribes and kerosene lubricant to snips.

You should practice on thin stock before risking a important material.

Steve

Can I not buy a mirror already cut to size: 5 X 16 X 0.8mm?

Or must I cut my own?

DT (dragon tiger) sells replacement mirrors for their scan sets. Or possibly Onestoplasershop would have one that would fit.

Thank you. I've got an email out to them both.

Finding a replacement mirror the exact dimensions of the broken one is proving to be more challenging than I originally thought. The mirror I broke on my DT-40W was the larger of the two, measuring 5mm x 16mm x 0.8mm.

One Stop Laser Shop offered some “universal replacement” mirrors measuring:
6mm x 11mm x .7mm mirror is $24.95 per mirror plus $5.85 shipping.
7.5mm x 13mm x .7mm mirror is $35.95 per mirror plus $5.85 shipping.

Jian of DT Electronics China offered:
9mm x 16mm x .8mm mirror for $9.00 + $35 shipping.

While the DT mirror is the most promising, since it seems to be at the length (16mm) the wide-angle DT-40W’s may need, it’s nearly twice as wide (9mm), suggesting to me it weighs close to twice as much as the original mirror. I’m concerned there will be a negative impact on performance using a mirror with twice the mass as the original.

I’m willing to pay DT’s steep shipping fees if it were a more precise replacement. Paying $35 to ship something that weighs about a gram is painful.

I see now why some people cut their own mirrors. At times like these, few things in life seem simple. :(

If I am to cut my own, where do I begin looking for raw materials to work with?

Good Sir PS -

Quote:

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Originally Posted by pschlosser

Finding a replacement mirror...is proving to be more challenging than I originally thought....If I am to cut my own, where do I begin...

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I think I may have been 'misinterpreted' when I was discussing the 'cut to save' technique... Here's a quicky diagram, irreverently (in kind jest.. :) in my best 'Chingrish', to show 'how to doo':

Attachment 38670 ..point being, since an 'X' really does not need all the 'translation' (length) of a Y, if both mirs are-of equal length (vs, ie: CTs, where the X is already a short, 'stubby' box, compared to the elongated, taper-cornered Y..) then you can do what is being proposed in the 'sex change' graphic :p and simply adjust the (former Y, now, 'X'..) galvo in the mount, to account for the shortening-up, and then re-tune both amps to play well together, again...

This is far-easier (..assuming you didn't already toss the Y remnant... :D than sourcing a new mir, at least for the 'time being'... And *certainly* easier than cutting from scratch, especially with über-delicate 0.8mm th stock! This is the technique often used by us old Sea Dogs, 'in the field', when spares are either not available, forgotten in the shop :p or... doh! you already broked the first set, and this *is* your spare Y.. :eek:

Dig? :)

Lemme know if this all makes sense, or if I am just bats.. :cool:
cheers..
j

Hi
Cant help with your current situation but you have some very experienced guys here offering help.

I have been in exactly the same boat myself. Jian ( of DT scanner fame) sent me new mirrors at no cost ( I was ordering another scanner at the time so no freight $$ for them).

What I would like to share is my policy of NEVER and I mean NEVER leaving the mirrors uncovered at anytime (other than live beam tests) when the lids off the case.

Jian always (or at least used to) supply a little cardboard box corner that covers the mirrors / scanner for shipping.... KEEP IT..

The moment I have one of mine open on goes the box cover and a couple of bits of masking tape.

I am currently doing an upgrade on an RGB with a Cambridge 6215. I even use one of Jian's box covers for that.
Strange, one of the best scanner companies in the world doesn't supply a cover but a modest Chinese scanner manufacturer does.. there's hope yet !!
Its also worth mentioning the really neat little case you get the DT scanners in when they arrive.... well presented I think.

I no sooner had covered the 6215 when ooops !! dropped a screwdriver and as usual, as if by some invisible force, it went straight for the scanner.
The cover was on disaster avoided. Beat ya this time buddy !!

So as a veteran of the broken mirror syndrome, may I suggest this as an idea for when you work on, handle, ship or whatever the scanner... put the cover on tape it down.
Also keeps the dust off while you work on the beast.

It has paid off for me several times and as recently as last week..

By the way I changed the broken mirror free hand very carefully and the DT40 Pro unit needed very little retuning... runs like a dream.
Maybe I just got lucky.

Cheers

Ray
NZ

Great advice, gentlemen.

Since I cannot get my hands on a mirror that's an exact (visually) replacement, I see the wisdom in reusing the broken mirror by flipping it.

As soon as Brother Jon and myself can arrange the loan of one of his jigs, I'll be on my way. :)

Real scan heads enclose the scanners. At least the ones I grew up using do. medical and marking systems do. Maybe there is a lesson here about adding a small metal box to most designs. In fact we mounted our scan heads on pivots, that rotated around the beam path,....

Hum, methinks its time to reinvent what works, yet again.

Steve

Good advice re the cardboard box supplied with the DT-40W (or any scanner for that matter) - I have kept my cardboard cover in place on my scan set since it arrived, only removing it to have a play (to make sure the scanners worked. Once I have lasers and have them aligned I will then remove the cover to do live beam tests and final alignment. I've already broken a mirror on a cheapy chinese set and do not wish to do so again with my expensive DT40W's :)

I've done exactly what dlsi_jon suggested above with perfect results every time, only I've never even clipped the edges. I just took what was left of the mirror, cleaned the slot in the shaft, replaced the remaining part of the mirror in the slot with the broken side away from the shaft, and used 2-part epoxy to glue it on the opposite side from the front surface mirror. Then it became the X-axis (if it wasn't already) since you don't need the full mirror's worth of room on that axis. No new parts, no retune, simple as can be. Really, seeing how wide that mirror is you can probably still keep it on the y-axis without losing much scan angle.

..Now preserved in The WikiMother... http://www.photonlexicon.com/wiki/in...in_Progress.29 :cool:

j