Blackhole 60W Laser

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Re: Blackhole 60W Laser

Postby TLHarrell » Mon Sep 05, 2011 11:24 pm

As others here have stated, the frame is a bit more flexible without the skins than they had believed. You may want to bolt on at least some of the skins to provide a shear support to each direction of the frame and only use the magnets where you really need the accessibility.
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Re: Blackhole 60W Laser

Postby iGull » Tue Sep 06, 2011 12:20 pm

Yes, you are absolutely correct, but I just don't like the appearance of external skins - and having worked in the semiconductor business for 40 years, I have had my fill of removing system panels that are attached with screws (especially on a Saturday late night emergency call) LOL :D :D

When designing the frame, I doubled up the 20x40 optical bench members and kept them 80mm apart, so that the X & Y axes and laser tube mountings have a rigid 'optical table' to work from (they also don't interfere with the skins). The corner supports are 20x40 as are the lower cross members. In between stuff is 20x20 - there's some movement for adding more struts for lower doors etc which would increase rigidity somewhat. The z table is also attached (at the top) to the optical table, so there will be a modicum of 'common mode' movement.

If there is any drastic movement, I can add thin aluminium diagonal struts internally across the lower back and sides where access is not too much of an issue. The panel skins are also a tight fit inside the frame aperture which should help matters. The electronics rack is lower right on pull-out slides.

Just need to suck-it-and-see and hope it all works out as planned (as if it ever does :D :D :D ).

Made a start to the framework this morning and built the lid - it's HUGE - I'll need to come up with a neat strut arrangement to keep the lid open - gas struts are definitely NOT on the agenda - another throwback from Saturday night callouts (I have a list of stuff like this to shy away from - unfortunately, fans are in there too :lol: ).

Cheers

Neil
EMOs are a sign of weakness ...
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Re: Blackhole 60W Laser

Postby iGull » Wed Sep 07, 2011 4:39 pm

Started building the rest of the frame today - lots of access holes due to using core screws rather than brackets. Built a simple chipboard jig to ensure relatively accurate positioning. Side frames completed.

Started gluing up the vee rails using my thin cyano method (well not mine, I'm sure hundreds of aeromodellers use the same process). I've attached some pix showing the process - gives you as much time as you need before committing.

Essentially, the process involves cutting all the materials to size and then give them a good wash down with cellulose thinners. Mark up the positions of the vee rails on the extrusion, then tape the rails to the extrusion starting at the centre of the extrusion then over the top to the other side. I used blue 3M masking tape. During the taping up, you can double check the straightness and lie of the rails. Make sure that the tape bridges over the gaps between extrusion and rail as we are going to run thin cyano down the gaps.
I double check everything before nuking it with the cyano - doing one rail at a time is sensible - you can also check using a vernier gauge that all is straight - mine were within 0.03mm (about 0.001 inches) across the length.
When happy with alignment, just tilt up the assembly and run thin cyano down the internal corner first until no more wicks in - then do the upper edge of the vee - start at one end and dribble some on the junction letting it run down and wick in - when it stops, move further down. Do the same for the other edge.
Don't overdo it and get cyano all over the place - be frugal. When it's all done, remove the tape - NONE of it should be stuck to anything or you have been overly heavy on the cyano. Wipe everything down with a cloth dampened in cellulose thinners. I used Thin Zap Cyano (pink) BTW - I'm sure that other thin cyanos will work just as well.

I've attached a pic of a pretest I did on some scrap extrusion and vee rail - I haven't managed to get it off using a hammer and length of ash timber all held in the vice - so no issues with strength here. Please ensure you do your own tests before trying this method as 'your results may vary' :lol:

Cheers

Neil
Attachments
P1000510.JPG
P1000509.JPG
P1000507.JPG
P1000505.JPG
P1000504.JPG
Test Piece.JPG
EMOs are a sign of weakness ...
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Re: Blackhole 60W Laser

Postby iGull » Thu Sep 08, 2011 9:28 pm

Managed to do some work in between other jobs today (I'm supposedly retired !).

Frame reasonably complete now - regular coke can perched on frame gives scale to the job - it's about a european single bed size :D
I assume that coke cans are the same size the world over - like Macdonalds burgers :D

Workshop is getting a wee bit cramped now. I'm really pleased with the rigidity of the frame, but there are a couple of areas where it can be improved (the internal skins haven't been fitted yet of course, but it's probably prudent to have it rigid without the skins).

One issue with using core screws is that you have to be ahead of yourself all the time - one out of sequence screw and you have to rip it back down again (bit like skin screws and knitting :D ) Only used four brackets so far too.

Cheers

Neil
Attachments
P1000512.JPG
P1000513.JPG
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Re: Blackhole 60W Laser

Postby TLHarrell » Thu Sep 08, 2011 10:12 pm

I just looked up these "core screws" you've been referring to. Hadn't seen them before. I'll have to consider them when I start my project.
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Re: Blackhole 60W Laser

Postby iGull » Tue Sep 13, 2011 12:07 pm

iGull wrote:One issue with using core screws is that you have to be ahead of yourself all the time - one out of sequence screw and you have to rip it back down again

Yes, I was right, I forgot to insert the upper Z table mounts which necessitated removing the optics bench then drilling and slipping in the mounts. When I put it back and trued it all up, I discovered I had put the bench back in '@rse for elbow' :oops: and noticed that I had drilled the core screw holes incorrectly on one side :oops: Not a productive afternoon ! However, a new day and taking some care has taken it to the next level.

Here's a picture of what core screws look like - you just screw them into the end of the extrusions, drill an access hole in the opposite piece then tighten them up using a Torx T25 driver.

P1000516.JPG
Core Screws


I found that using my little Makita impact driver made the job a whole lot easier !!!

I turned down four acetal inserts with M8 threads for the Z lift nuts - they are just turned from 20mm acetal barstock and pushed into a 20mm hole in the extrusion. The inserts are held in place with a couple of M6 grubscrews down the extrusion. I think there will be enough slack in the arrangement with M8 threaded rod and 8mm skate bearings above and below to allow the system to work. The threaded rod is rolled and is a tad under 8mm diameter.

P1000515.JPG
Z Lift Inserts


P1000519.JPG
Z Lift mechanism 1


P1000521.JPG
Upper Z Lift Bearing


The framework is pretty much complete now - I added some short stiffeners at the centre of the rear hinge support bar and one at the front of the frame. I'd like to add four more short stubs of 20x20 around the periphery of the optical bench for good measure (but I'll be using brackets, I've had enough of tearing it down :lol: )

P1000518.JPG
Main Frame Updated


This is the arrangement for mounting the laser tube - this is in 6mm MDF for test purposes - the inner of the opening is lined with 1.5mm silicone from a baking sheet I purloined from the kitchen drawer :roll:

P1000522.JPG
Laser Mount


I have +/- 5mm adjustment in X&Y - hopefully the laser will be fairly axial.

Thought I'd attach a pic of a cleaner I've used for a lot of years - especially for granite optical tables etc - but it works really well for cleaning anodised aluminium extrusion - called Chemsearch 'Sparkle' - it is an abrasive in a foam - the foam has a whiff of WD40 about it. No idea where you can buy it now - try Google.

P1000517.JPG
Sparkle


A few minor mods to the acetal parts before I commit to cutting.

Cheers

Neil
EMOs are a sign of weakness ...
iGull
 
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Re: Blackhole 60W Laser

Postby dirktheeng » Sat Sep 17, 2011 2:27 pm

TLHarrell wrote:As others here have stated, the frame is a bit more flexible without the skins than they had believed. You may want to bolt on at least some of the skins to provide a shear support to each direction of the frame and only use the magnets where you really need the accessibility.


I can attest to this... when I used my leveling feet to adjust the frame without the skins on, I could go from end to end with a level foot and still have all 4 on the table. After putting on the skins, the frame is solid and I have to be precise with my feet otherwise they lift off the table and it rocks. I would be sure to level and square your frame b/4 you tighten down the bolts on your skins. It will lock it in that config once tight.

Also, your frame is significantly bigger than the 2.x laser with travel distances that look to be much longer. I think you need to look into using much better mirrors than we have with very fine pitched adjusters. Even with the small travel we have now, just barely touching the adjuster on the mirror moves the beam significantly at the end. I can't immagine trying to adjust the beam with the mirrors we have if my travel were double what I have now. I would also suggest adding some micro adjustability to your laser mounts. It would suck to have to try to move the laser up/down to hit the last mirror in the middle without that. I think that is why most of the mounts you see have 3 screws around the perimeter. Moving the laser laterally isn't as critical becaue you can move the laser head forward/backward, but getting it up and down is not really easy... better to move the laser up/down.
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Re: Blackhole 60W Laser

Postby iGull » Sat Sep 17, 2011 9:46 pm

Hi Dirk

This is a long shot, but you're not the same Dirk the Danish engineer that used to work for QC Optics in Connecticut are you ??

Anyway ...

dirktheeng wrote:I can attest to this... when I used my leveling feet to adjust the frame without the skins on, I could go from end to end with a level foot and still have all 4 on the table.


Ouch, then you do need to stiffen up your frame :D

I take on board your concerns for the stiffness of my 'wee' laser cutter :D

I have owned an accurate machinist's level for a number of years and use it at each stage of the build process. If I screw one foot too high, then another one comes off the floor too - my frame is pretty stiff. The main frame, the 'optics table' is built from two sections of 20x40 - spaced at 80mm. The frame is held by eight core screws at each corner. The frame corner 'legs' are 20x40 as are the lower cross members. Everything else is 20x20. I'm satisfied that it's rigid enough (I think :D ) - sans skins. I'm wondering if there is an issue with using diecast brackets ? For sure, they certainly make life easier during the build, but I'm a tad concerned when they are used singularly. The one flexible part is the lid - but to be honest, that doesn't matter ( I haven't put the 6.35mm perspex sheet in yet so it might get better :D )

dirktheeng wrote:I think you need to look into using much better mirrors than we have with very fine pitched adjusters. Even with the small travel we have now, just barely touching the adjuster on the mirror moves the beam significantly at the end. I can't immagine trying to adjust the beam with the mirrors we have if my travel were double what I have now.


I'm using 25mm Coletech mirrors and mounts along with their air assist final lens assy - not the slightly cheaper variety on the .2x (I'm not castigating the .2x BTW - far from it !!!) - the screw pitch looks to be around 0.25 to 0.5mm on the mounts FYI .

dirktheeng wrote:I think that is why most of the mounts you see have 3 screws around the perimeter. Moving the laser laterally isn't as critical becaue you can move the laser head forward/backward, but getting it up and down is not really easy... better to move the laser up/down.


:lol: :lol: - a bit of my history - I'm sixty years old and have worked in the semiconductor industry for the last 20 years and the previous 20 in the commercial military electronics business as a systems engineer and test equipment design engineer. My first experience of lasers was designing and building the laser PSU (using selenium stick rectifiers :D ) back in the late sixties then designing and building the mechanical mirror mounts to hold the primary and secondary mirrors (they weren't integrated way back then :D ). You had to align them manually with your last good eye and a bit of toilet paper :D I have extensive experience of aligning laser systems in lithography systems - mainly LMS and exposure lasers - I have spent many painful hours aligning other people's systems. One of my pet hates is trying to align a laser using the three screw 'system'. I think it must have been a woman that invented it (did I just say that - the PC nazis will be after me :D ) - honestly, why would you want to offset the laser at 45 deg during an alignment when what you want is an orthogonal adjustment ??? My brain could certainly never connect with this. The best system (IMHO) is a dual XY stage - but like all things, compromise (cost usually) is a necessity - so we use something else (have a look at Newport's XY optical stages for laser/whatever alignment - then look at their horrendous prices). While my system may look a bit agricultural to the 'uninitiated', there is some madness in the design - it's based on friction. The tube is VERY well supported in the two circular mounts, unlike the .2x system where the laser is ONLY supported on two 'points' (I am bashing the laser mounts, sorry Bart - I think you got them upside down ?). When the tube is loosely 'snicked up' in my mount, you can insert a flat bladed driver or allen key into the space between the frame and the mount and tweak the laser mount position - adjustment is available in X & Y - INDIVIDUALLY and NOT at 45 deg - laser alignment then becomes very much easier.

Rigidity in the rest of the system is also important - especially in the 'optics table' and anything attached to it. I'm using 6mm acetal plate (because I had two sheets really :D ) - it also machines well and is very rigid.

/rantModeOff :lol: :lol:

I cut and finished some acetal parts on my CNC this evening (before the first glass of wine :D ) - the belt mounts and clips mainly along with the secondary mirror mount - all looking clean so far.
The rest of the stuff should hopefully get cut tomorrow.

It's getting to an exciting stage in the project now when all the electronics/mechanics/liquids/air come together - then you see all the faux pas that you made :lol:

Cheers

Neil
EMOs are a sign of weakness ...
iGull
 
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Re: Blackhole 60W Laser

Postby iGull » Mon Sep 19, 2011 11:56 am

Was busy at the weekend cutting the rest of the acetal parts...

P1000523.JPG
Acetal Component Parts



Made a few minor changes to the final parts after cutting out some test pieces in MDF. Some of the holes were incorrectly sized, but I just opened them up in the drill press. I've added the silicone strips to the laser tube mounts - the strips are in a fetching red colour :D Nothing really adheres to silicone strip (after all, that's what it's designed to do I suppose :D ) - I used double sided tape. Tape probably won't last long - most man-made 'self-adhesives' seem to fall apart after a few years :x

There was some chatter on the lists a while back about belt pulleys and M5 screws I think - I've always used 'shoulder screws' for those type of jobs (there's one in the pic above) - they come in various sizes and have an accurately ground shaft (unlike the normal rolled screws) - they're cheap too - I think I got those on evilBay as I was buying some other bits at the time.

Spent what seems a fortune on screws/washers/nuts this morning - all stainless as they were nearly as cheap as nickel plated or black (in the hope that they won't corrode with any of the nasty gases that might be emitted - probably an overkill). I also spent another mini fortune on Bosch M4 tee nuts for all the parts and accessories. Having been in engineering all my life, all those things were available to hand (so to speak :D ) - being retired means having to get your own - I even had to purchase a reel of solder recently - something I've NEVER done :D :D

Pic also shows the Coletech optical parts - bit better quality than the standard chinese offerings (with finer adjustment on the mirrors etc), but nowhere near as good as European or US made 'industrial' optical components - you get what you pay for I guess and they'll be fine for what I'm using them for.

I've used Bart's vee wheels with the single bearing for this job - I think I'll upgrade them to the dual bearing versions when they become available. I think the new ones will be much more rigid when the machine size gets bigger. The single bearing ones will be fine for now 'though - they worked first time with no jamming on the large rails I have - I've never experienced that before ! There always seems to be a long tweaking period involved with regular linear bearings. They are extremely quiet too.

Cheers

Neil
EMOs are a sign of weakness ...
iGull
 
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Re: Blackhole 60W Laser

Postby dirktheeng » Mon Sep 19, 2011 10:00 pm

iGull wrote:This is a long shot, but you're not the same Dirk the Danish engineer that used to work for QC Optics in Connecticut are you ??



no I'm not... I'm dutch
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