Blackhole 60W Laser

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Re: Blackhole 60W Laser

Postby iGull » Tue Nov 22, 2011 4:36 pm

Apologies Mike, I missed your question ...

mikegrundvig wrote:I'm very glad to hear it's working great. I'm going to take a partial assit on this one with my comment " Do you know you are getting the power you expect?" :)


Actually, I suppose the answer is no, but judging from what others can cut with 40W and that I can exceed that by a decent margin - single pass on 9mm MDF, 3mm liteply at 4000mm/min - I'm fairly happy that it is putting out a good bit more than 40W. I don't think the power output will be linear for cutting - for instance - 6mm at 40W will most likely need a lot more than 80W to cut 12mm at the same feedrate - I'd be interested to see if anyone has any figures on that.

Cheers

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

Postby iGull » Thu Dec 08, 2011 10:07 pm

The Emperor's new clothes :-)

Eventually got around to getting some panel material for the machine. I had intended getting 'Aluply', but when at the distributor, he offered another material which was a 'clone' as far as I could see - called "Adabond" - looks exactly the same, same thickness, same core, same colours as aluply - except that it is about half the price ! Of course, that's what I bought ! I had always intended getting yellow, but nearly changed to the nice poly blue - but it's just so common on machines these days LOL :D

Cut all the panels on the table saw with an 80T blade - cuts just fine - just a matter of rubbing off the swarf with a thumbnail. I set up a jig on the pillar drill to do all the holes - I had intended using magnets, but after some 'sticky' issues, moved over to stainless button capscrews and laser cut acrylic tabs that are a friction fit in the extrusion grooves - there are M4 panel nuts crimped to the tabs.

P1000973.JPG
Laser cut acrylic tabs


P1000971.JPG
Machine rear


The design of the machine was to include all the peripheral stuff inside - cooling, extraction and air assist. The space under the 'smoke plenum' was the intended area. I've fitted a 150mm (6") mixed flow (560m^3/hr) 'vent axia' brand inline fan unit to the base and added a purpose built inlet to the base of the smoke plenum (with a hat to stop all the cut bits getting sucked off :) )...

P1000969.JPG
Fan inlet


P1000972.JPG
Fan Inlet cover


The outlet of the fan is a hundred millimetres or so away from the workshop wall and is a straight outlet - no bends or restrictions to add pressure to the system. I'll give it a smoke stick check once I get the rest of the covers screwed on and post a video. It is VERY quiet - I don't have a sound level meter to hand, but the spec says 47dB(A) at 3m. I'm aware that the fan should be outside in case the hose bursts on the outlet side and into the workshop !

The electronics/power drawer is nearly finished, so should be able to get on with some serious controller testing now. I've left off the water chiller for now - it's all wired, but after a pile of cutting, the water was hardly warm (it's a 12 litre flat container).
I have a design for a flow meter that fits to the open end of the outlet pipe rather fitted than inline (bad memories of gummed up flow meters causing flow to stop moved me in this direction). It's cut from acrylic and like the pump is submersible - bit like one of those 'treasure chests' that you see in aquariums. If it fails, the flow water is not restricted.
Just a few magnets rotating against a reed switch - needs something to check that the switch is opening and closing - I'm using a picaxe - part of a 'utility processor' that handles the temperature and z motor, but any old micro will do the job - even an LED and a capacitor should work. Once I get the thing cut, I'll post up the design.

Cheers

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

Postby TLHarrell » Thu Dec 08, 2011 10:51 pm

I like your idea of including all the additional support equipment inside the case. It's looking good, even in yellow (not really my favorite color). Too bad the magnets didn't work out.

How's alignment and accuracy working out for you on the 4' axis? Any issues, or anything you would plan differently?
40w Full Spectrum Engineering 5th Gen Hobby 20"x12" w/ Rotary Engraver
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Re: Blackhole 60W Laser

Postby mikegrundvig » Fri Dec 09, 2011 9:12 am

Any details on the magnets? I'm curious to know where the problem was. Thanks!

-Mike
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Re: Blackhole 60W Laser

Postby iGull » Fri Dec 09, 2011 4:54 pm

TLHarrell wrote:I like your idea of including all the additional support equipment inside the case. It's looking good, even in yellow (not really my favorite color). Too bad the magnets didn't work out.

Thanks, the support stuff has to go somewhere and it's just as easy to build a taller cabinet as it is to build a separate table and have all the pipes and stuff lying all over the place. Actually blue or yellow were my first choices, they didn't have the polychrome blue - so ... :lol:
TLHarrell wrote:How's alignment and accuracy working out for you on the 4' axis? Any issues, or anything you would plan differently?

Apart from forgetting to align the four corners last time I did a realignment (I had replaced some screws I didn't have at the time) - and melting a hole in my workshop printer because of it - really no major problems at all. Typical laser alignment - could really have done with another body to help as the machine is so big (three eyes instead of just one :) ) - I ended up making a long cable with a pushbutton to fire the laser remotely while I adjusted the mirrors. Use of dymo labelwriter labels is great - self adhesive and you can print the exact size target on - saves a LOT of guesswork over till receipts and masking tape.
To be honest, there are only a couple of minor things I would change - the 'optical table' members are only 80mm apart I could have done with 90 as the right angle torx key doesn't quite fit. The middle body rail could do with being made of 20x40 rather than 20x20 - it would have been easier to fit the plenum floor. I'm not sure that I would bother with the autofocus and Z lift again - it would be a whole lot easier and cheaper to just have a solid fixed bed with a range of positions the bed could be put in - I may yet retrofit this idea.
The coletech laser head adjusts over about 30mm or so and it's easy to just use a focus gauge block and tighten the tube to it (like a lot of 'pro' machines do).
The Igus energy chain is not that great (it's the smallest with an 18mm bend radius) - it tends to curl up rather than smoothly traverse in X - I couldn't get the Kabelschlepp stuff (I have it on my CNC router and it's much better).
One point I would DEFINITELY recommend is using core screws over right angle brackets - it is MUCH more rigid (and hugely cheaper). Ok, on the downside, it is a pita to drill the holes to access the core screws and you have to keep aware when building otherwise you end up with the 'insufficient panel nuts' problem in the 2.x and have to strip it down to refit the member you forgot :lol: There's also no major adjustment, so you need to know exactly where it's going.

Mike wrote:Any details on the magnets? I'm curious to know where the problem was.


Yes, my original intention was to use neodymium magnets to hold all the panels on - same system as I have with the screws currently, but magnets in each of the tabs and mating magnets adhered to the back of the panels (I've used it on standard panels a few times). The problem was keeping the magnets attached to the panels - it must be the paint that is on the reverse of the aluply - every adhesive I used (I tried many - cyano/acrylic/gorilla/epoxy etc etc) eventually pulled off (no, there wasn't a polythene film attached :lol: ). By this time, I didn't fancy grinding away the paint at each point (120 stations) to get a clean aluminium surface, so I chickened out and used button screws with captive grip nuts in the acrylic tabs. Maybe at a later stage I might try something else - meanwhile, I have lots of more important things to do :-)

Cheers

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

Postby mikegrundvig » Sun Dec 11, 2011 4:36 pm

IGull wrote:I'm not sure that I would bother with the autofocus and Z lift again - it would be a whole lot easier and cheaper to just have a solid fixed bed with a range of positions the bed could be put in - I may yet retrofit this idea.
I've been following your build with great interest for quite a while now as it's the most similar to my intended build on this forum. Care to elaborate on your table/focus comment in more detail? I'm currently debating how I want my table movement to work and so any advice from someone who has "been there, done that" would be greatly appreciated.

-Mike
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Re: Blackhole 60W Laser

Postby iGull » Sun Dec 11, 2011 8:02 pm

mikegrundvig wrote:I've been following your build with great interest for quite a while now as it's the most similar to my intended build on this forum. Care to elaborate on your table/focus comment in more detail? I'm currently debating how I want my table movement to work and so any advice from someone who has "been there, done that" would be greatly appreciated.


Hi Mike

Well, it's all just too easy to add 'gadgets & gizmos' to a system - it's much more difficult to stand back and add less ! Interlocks, things that switch fans on/off, water level and flow monitors, automatic fire extinguishers, autofocus systems and extra processors, blue flashing lights etc etc - the list is endless - some engineers and folks that like to build stuff have this serious over-engineering problem :D . My experience is that the more there is, the more there is to go bad at the wrong time. You need to stand back and ask yourself what you REALLY need and could you keep it simpler.

This leads us to the autofocus/z lift system. If you have a laser nozzle that is not adjustable in height, then it follows that you need a fully movable system to adjust the table height instead. I initially went for the four corners (I was just following the fashion here without giving it too much thought - I actually have a coletech focus tube !), leadscrew belt and stepper approach thinking that was what was really needed - which seems great when you are designing it, but in practice, isn't that wonderful. On the smaller bed size, the 'leadscrews' (read threaded rod, not real leadscrews :) ) you can just about get away with M8 or M6 size threaded rod and some loose nut system to take up the inevitable inaccuracies. You can even get belts that fit that size too ! The bed isn't that stable (even though the screws are in tension) and will vibrate with stepper motion/resonances (which telegraphs it's way to the laser cut of course). What you need to do then is perhaps add sliders bolted to each of the corners and the frame to give that stability - then you have the vertical alignment issues trying to stop the whole thing from jamming up. We haven't even started to align the bed height to the laser yet - depending on the lens you are using, then you really want the bed to be within no more than 0.25 to 0.5mm (and that is very roughly) across the whole table. While aligning the bed sounds trivial, when it gets to be 1.2 metres long, you can't just stretch across for a wee tweak of the leadscrew :lol: It's very difficult to find a supplier to get the belt size you want too (I had to get mine specially made after failing miserably to get a chain working). BTW, tweaking the leadscrews to get the bed the same height IS relatively easy - just don't touch anything when you are refitting the belt (or tightening the locking grubscrews - which is another story :D )

FWIW, my advice would be to have a simple system of four 20x40 vertical rails 'match drilled' (pillar drill all four while taped together), parallel and securely bolted to the frame. The match drilling would fit four sprung and lockable pins in the table frame - keep one as a permanent reference then adjust each vertical rail in turn until the whole is dead nuts on. Moving the table up and down is a simple matter of locking back each pin and sliding the whole table to the height required - it can't be at the wrong height because you match drilled them. It's important that the table be rigid too of course - I'd go with the 'corner cube' connectors again - they work very well. There are no electronics/water/high voltage/software involved to go wrong in the system :D

You definitely don't want my advice on a gantry system 'though - moving glass/gas/water/25Kv/sensor cables and air is a recipe for trouble - go for it 'though - no gain without pain as they say :D :D :D :D

On another note, I was reading a post somewhere (maybe here) about someone 3D'ing a laser air assist nozzle - presumably from ABS - it reminded me of an appropriate engineering term 'about as much use as a chocolate fireguard' :D :D :D :D

Cheers

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

Postby mikegrundvig » Sun Dec 11, 2011 9:42 pm

Thanks, that table discussion was very helpful. I think I'm going to build the table exactly as you suggested. Probably using something like these to lock it into position.

iGull wrote:You definitely don't want my advice on a gantry system 'though - moving glass/gas/water/25Kv/sensor cables and air is a recipe for trouble - go for it 'though - no gain without pain as they say
Heh, I'm debating with myself pretty heavily on the gantry tube system. Too many of the large commercial lasers do it for me to disregard the design out of hand and it actually makes for a simpler overall structure as you don't have as many structural members critical in the alignment. Running the HV wire doesn't worry me, as I'm just going to use much higher grade than the machine calls for. My only real concern is running water to the tube as it will need to flex frequently. The weight of the gantry even with everything on it isn't much of a concern at all. I'm using 36v steppers with higher-end drivers than most here so I'm not at all worried about either the power or speed problems.

Thanks for sharing your experience!

-Mike
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Re: Blackhole 60W Laser

Postby iGull » Sun Dec 11, 2011 10:24 pm

mikegrundvig wrote:Thanks, that table discussion was very helpful. I think I'm going to build the table exactly as you suggested. Probably using something like these to lock it into position.


I've seen those used in loads of applications - one of which was to lock ejector seats in position ! - I think they'll be perfect if installed correctly. If you want to get fancy, I remember a matching steel sleeve bearing that goes with them - don't ask me for a link 'though :D This is all assuming that you have an adjustable optic tube for the laser head of course !

Ok on the gantry, I can see some indecision creeping in there - hold on to that thought :D :D :D

Cheers

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

Postby mikegrundvig » Sun Dec 11, 2011 11:57 pm

iGull wrote:This is all assuming that you have an adjustable optic tube for the laser head of course
I'm building my own optics carriers for a variety of reasons so I'll just add this to the mix. This is also something common on the larger format machines.

iGull wrote:Ok on the gantry, I can see some indecision creeping in there - hold on to that thought
Sorry, not near enough doubt to really change anything. With the gantry-mounted-tube being so common on large lasers, I'm sticking with it. As best I can tell, when you get into the 4' stuff for industrial use the flying optics become less common.

-Mike
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