CO2 Lasers. - Oldal 22

Dátum/Date: Szerda, 2015-01-14, 13:19 | Üzenet/Post # 421

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Hi Marko,

Thanks for posting the link to your pictures.That's an absolutely excellent build quality on your machine, mycongratulations sir.My opinion on your non-straight lines…Perhaps firs check that your focus lens is not loose in itsholder (an ‘O’ ring usually insures this) and also check that none of your
mirrors are loose.Otherwise, I think the problem is mechanical – possibly yoursteppers are producing jerky movement. What micro-stepping setting are you
using ?. It could also be related to the belts not running smoothly on their
pulleys etc. but in any event, I think, the mechanics should be investigated.
I notice that you are also getting ‘dots’ at the start / endof drawn lines. This is usually caused by the laser being switched on too early
or being switched off too late (or both). Mach3 solves this problem with the
M11/M10 commands (which only switches the laser at the exact time of axis
movement) no doubt other machine control software’s have a similar thing which
you may need to investigate.Hope this helps.Tweakie.

Success consists of going from failure to failure without loss of enthusiasm.

mbarosevic

Dátum/Date: Péntek, 2015-01-16, 08:00 | Üzenet/Post # 422

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i didnt have time to play with setup. My idea is to put higher microstep on drivers, and try to put acceleration for stepper motors as high as possible.
You can see on images that cutting shape is not straight! Most problem is corners and round adges.

Hozzáadva (2015-01-16, 08:00)
---------------------------------------------
@tweakie
For now microstep on drivers is 1/16. I think that is enough, but i'll try to put it more because now is working without reductions.
Focus - lens need to go more up, engraving line is to thick, you are right!
Mirror adjustments is good, i put a lot of time to make it right.
I see that is a problem with turning on/off laser beam. For now it is connected to direcrion signal of z axis. I have put simple circuit with transistor bc337 to be a switch and prevent from turning on beam when mach is on and machine is not working.
I will try to solve this problem with M11/M10 command, but first i need to find some instructions for that smile

Thanks for help, Marko

Dátum/Date: Péntek, 2015-01-16, 08:10 | Üzenet/Post # 423

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Idézet

I will try to solve this problem with M11/M10 command, but first i need to find some instructions for that

This & the following comments may help http://hobbycncart.com/publ....-1-0-29

Tweakie.

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Dátum/Date: Vasárnap, 2015-01-18, 17:03 | Üzenet/Post # 424

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Hi boys!
Did anybody try to cut plywood? It seems really hard for Me, 5mm thick material is not easy to cut with 40W. Needed 6 or 7 pass at full power.

Dátum/Date: Vasárnap, 2015-01-18, 17:40 | Üzenet/Post # 425

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Hi Zoltan,

Some types of plywood cut better than others - I have concluded that it relates to the type of bonding adhesive used in it's manufacture. Generally 60 Watts and upwards is used but it can be done with 40 Watts if you use high pressure air assist. At 40 Watts carbon is produced in the kerf and this has to be blown away for the laser to penetrate. A fair size compressor (capable of continuous duty cycle) is required and if, like me, you use co-axial air assist the compressor has to be of the oil-less type to avoid focus lens contamination. Unfortunately, cutting plywood is not as straight forward as it seems. sad

Tweakie.

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Dátum/Date: Vasárnap, 2015-01-18, 19:21 | Üzenet/Post # 426

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tweakie, thank You, it illumines a lot of things I tried. On an other forum the boys report they can cut the plywood with only 2W blue laser with air blowing on the cut. I thought with 40W it can't be so hard. The aquarium pump I use now is able to keep the lens clean, but not blows the fume away from the wood's surface. Earlier I had a strong dirt on the lens, and couldn't clean perfectly. As I see the wood rather burns, the cut became wide and black. Next week I will get some thinner (3mm) plywood, hope the adhesive in it will be easier to cut. I have an oil-free compressor, able to work long time. I try to make a new cone for the head and get an air spiral hose what isn't so big.

Dátum/Date: Vasárnap, 2015-01-18, 19:29 | Üzenet/Post # 427

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I tried to cut 3mm plexiglas, I could't go over 4mm/s with it. Maybe I decreased the efficiency of the lens with the fume vaporized on it. Shouldn't it be faster?
Here are the result:

The box was designed by the Boxmaker.

Csatolások/Attachments: 2648836.jpg(217Kb)

Dátum/Date: Hétfő, 2015-01-19, 06:39 | Üzenet/Post # 428

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Nice work with the box.

I find the cast acrylic cuts better than the extruded acrylic but perhaps that is just me. If it's any help, I usually use 300mm/min feed-rate and the minimum power level necessary to penetrate the work.

Tweakie.

Success consists of going from failure to failure without loss of enthusiasm.

Dátum/Date: Hétfő, 2015-01-19, 07:26 | Üzenet/Post # 429

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tweakie, I don't know which type of plexiglas I had. How many Watt is Your machine? I'm not sure if chinese says it's 40W than it really is. Is there any cheap way to measure the output wattage?

Dátum/Date: Hétfő, 2015-01-19, 08:08 | Üzenet/Post # 430

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Hi Zoltan,

My tube is 40 Watts but that's just what the Chinese manufacturer's say it is - I have no accurate way of measuring it.

Tweakie.

Success consists of going from failure to failure without loss of enthusiasm.

Dátum/Date: Hétfő, 2015-01-19, 12:51 | Üzenet/Post # 431

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tweakie, thanks! I will investigate the lens again, if I can clean it. I saw some equipment on the net what can measure the power, but the prices are horroristic.

Dátum/Date: Hétfő, 2015-01-19, 13:29 | Üzenet/Post # 432

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Take care with lens cleaning it has an AR coating which it is best not to damage.
If it's any help, I use isopropyl alcohol and camera lens tissues.

Some power measurement devices have been home built and it is not that complicated - I will see if I can find some details and report back.

Tweakie.

Success consists of going from failure to failure without loss of enthusiasm.

Dátum/Date: Hétfő, 2015-01-19, 13:42 | Üzenet/Post # 433

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Hi Zoltan,

The power meter details I was thinking of are here http://www.prutchi.com/2012/02/05/d-i-y-co2-laser-power-meter/

Tweakie.

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Dátum/Date: Hétfő, 2015-01-19, 17:49 | Üzenet/Post # 434

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tweakie, that is a real hobbyst solution, I think this man made it the best way. Some day I will make a similar thing.
I started to build the nozzle from parts I found in the workshop. I found the original nozzle on Ebay, but it takes a month until arrives, and sometimes I can be impatient smile

Csatolások/Attachments: 9621752.jpg(142Kb)

Dátum/Date: Kedd, 2015-01-20, 06:41 | Üzenet/Post # 435

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Hi Zoltan,

Nice looking nozzle - excellent job using recycled parts.

If it's any help a group of us, here in the UK, have tried various nozzle exit hole sizes and 3mm diameter appears to be the best all-round solution.
(For special applications, where a smaller exit hole, is required others have fitted a baby's feeding teat over the top and then let the laser beam create it's own hole - I am not sure about the effectiveness of this but I am told it works).

Tweakie.

Success consists of going from failure to failure without loss of enthusiasm.

Dátum/Date: Kedd, 2015-01-20, 06:53 | Üzenet/Post # 436

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tweakie, thanks!
The idea that the laser creates its own hole is really genious, I have little plastic caps that will fit to the top of the nozzle. I will try it.

Dátum/Date: Kedd, 2015-01-20, 16:49 | Üzenet/Post # 437

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I foud out that I will need to drive the air to the laser head, so I need a spiral air hose. I was searching on the internet for small winding diameter spirals, becuse the normal spirals were too big, I have not enough space under the safety door. I found a Festo tube with 46mm winding diameter. After a call to the local dealer it was coming out that a 1.2m long tube costs 51USD without any fitting. Because I only need a 300mm piece, and because I'm a hobbyst, I tried to make a spiral from a normal PA (polyamide) tube. I fixed one end on an aluminium tube (I found this useable diameter) and tightly winded up the tube. After fixing the other end I tried to heat up the whole thing with an electric heat gun. The results were ugly, but it showed that I'm able to form the PA tube with heat:

After that I thought that I need a smooth warming, every centimeter needs the same temperature to be formed well. In my workplace We have a hot air owen. I took the new winding into it and warmed up to 145°C. The time was ca. 20 minutes, because the owen needed this time to reach the temperature, it's a big owen. When I took out the tube I left for cooling out for ca. 10 minutes. Here are the results:

Now I'm (and You too) able to make a custom size spiral hose in any diameter and lenght.

Csatolások/Attachments: 7105646.jpg(245Kb) · 5915428.jpg(352Kb)

Dátum/Date: Szerda, 2015-01-21, 06:43 | Üzenet/Post # 438

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Absolutly brilliant Zoltan, thanks for sharing the idea and information on how to do it.

Tweakie.

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Dátum/Date: Szerda, 2015-01-21, 15:36 | Üzenet/Post # 439

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tweakie, thank You!
Here is a little update: today I tried PU (polyurethane) tube, and it works the same way.
Can be important that this material is much softer than PA, so the laser head needs less power to pull it out.