building a laser cutter

Questions, Suggestions, Tips, Etc

building a laser cutter

Postby Nikos » Fri Sep 14, 2018 12:03 pm

Hello there,

I am new on this forum.
I started to design my 60W Laser cutter and I have some questions, I would be grateful if you can help me.

The machine will have one Nema 17 stepper for the X axis and two Nema 23 for Y and Z axis, the drivers will be the Geckos G201X.
I'm confused about the steps per mm because I would like to move the axis with 20 tooth pulley GT3 3mm pitch.
When I'm making the calculation (Motor step angle * Sriver Microstep) / (Belt Pitch * Pulley tooth) I've got these relults:

(200 * 10) / (3 * 20)= Steps/mm: 33.33333333, Resolution: 0.03.
Is this ok or I will have a problem, something like error? loosing steps?

If I change the belt pitch to 2mm the result is= Steps/mm: 50, Resolution: 0.02.
I'm thinking to use 9mm width belt.

What do you suggest me?
Thank you in advance,
Nikos
Nikos
 
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Re: building a laser cutter

Postby Techgraphix » Fri Sep 14, 2018 2:14 pm

Depending on the controller you like to use is the resolution given in um/step.
The maximum speed also depends on how many steps you have to make to travel 1mm
In respect to de selected motors and drivers:
the Gecko's (as far as I know them) are very limited with microstepping.
IMHO a better choice for X and Y are the (Leadshine) closed-loop steppers/hybrid servo's. they do 4000 pulses/rotation.
If you chose a 40Teeth GT2 pulley for the X-axis (I prefer to use the 10mm wide belt with the stainless steel wires in it, the white one) every rotation will be 80mm.
With 4000pulses per rev, this will give you 80/4000 = 20um/pulse.
While these closed-loop motors have only one axis (the other is occupied by the encoder), you have to make an reduction to drive the Y-axis on both sides.
I often use a reduction from 25 to 36 Teeth in the reduction and drive the Y-axis with 32Teeth pulleys.. This give a 11.11111111 um/step in the Y-axis.
For the Z-axis (the table) I use the normal T5 belt with a normal stepper of 2NM. On the motor is a 10T pulley and the 4 ballscrews are driven with 20Tpulleys.
With a normal 2NM stepper this is able to lift over 40 kilo's.
If you haven't bought the steppers and drivers already, this is something to consider.
I have build about 6 lasermachines that are used every day.. These are very fast and reliable.
Kees
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Re: building a laser cutter

Postby Nikos » Fri Sep 14, 2018 9:01 pm

Techgraphix Thank you for your answer.

This version of Gecko's has only 10 microstep option.
I have also a CNC and I control it via Gecko G540 and I'm very happy. Works perfect without any problem but it has ballscrews, the belt drive it's different as I know.
I checked the Leadshine hybrid steppers and they are a bit expensive.
I think your version is very stable but it looks a bit complicated for me.

From your experience do you think that I will have problem if I use the first version with GT3 belts and 20 tooth pulleys?
I'm asking you because the steps/mm will be 33.33333333.

I wanted the GT2 2mm belt but I can't find it somewhere in Europe at 9mm width.

Thank you
Nikos
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Re: building a laser cutter

Postby Techgraphix » Fri Sep 14, 2018 9:39 pm

Oh, I don't even look in Europe.. Most of the materials I use I order in China (Ebay, AliExpress, Banggood etc)
Most of the time it's free shipping (how they do that?? while I have to pay a little fortune to get my stuff over there)
I just pay them with PayPal.. if it doesn't arrive, doesn't match the subscription or is a fake, I will get my money back.
Some things like lasertubes and HF-spindle motors have arrived within 24 hours!! normally it takes one or two weeks.

Yes, Leadshines are a bit more expensive, but since I used them, my machines are 3 times faster and never one step lost..
I pay an average of 140 euro for a driver and motor (Nema23 2NM) When I buy a decent 2NM motor and a Gecko I have to pay around 100$
You only need two of these closed-loop sets so what is 80 euro's on the grand total? Absolutely worth the difference in price.

For Nema17 closed loops I use them from another brand. cheaper too..
We just received a few of those sets to retrofit a big GCC-laser but that project is still in progress so I can't tell you wat my experiences are with those.

Kees
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Re: building a laser cutter

Postby Nikos » Tue Sep 18, 2018 5:28 am

Hello Techgraphix,

I'm so sorry to my late reply.
I will check all of the suppliers to find exactly the parts that I would like.
I'll check also the Leadshine steppers and drivers.

Maybe I'll buy also the AWC708C controller because I want to do and raster engraving.
Do you work raster engraving and with what controller?

Thank you!
NIkos
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Re: building a laser cutter

Postby Techgraphix » Tue Sep 18, 2018 1:39 pm

I use the AWC708C (or LO-X7, which is the same) all the time.
IMHO it is a very fine controller to build a laser. Engraving is very good, cutting also.. Every parameter can be set in the software (LaserCAD)
It is easy to use, reliable and solid with plenty of options..
Kees
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Re: building a laser cutter

Postby Nikos » Tue Sep 18, 2018 1:44 pm

Thank you very much for the info.

I will inform you when I'll have news.
Have a great day!
Nikos
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Re: building a laser cutter

Postby george » Mon Oct 15, 2018 1:03 pm

Hi Everyone.

I am also new in this forum, and i have also decided to build a laser cutter.

Some background: i am a mechanical engineer, and have very good experience with electronics, (i have made a pmsm motor controller from scratch etc).

So i was able to find pretty much all mechanical components. I am building an assembly in solidworks so i have a better grasp of the procedure etc, and also do some modifications to accommodate a 80W tube. (which by the way, i am going to post in the forum after its done)

With that in mind, i have never ever done anything with stepper motors/belts/cnc so i am incredibly confused about the electronics that i need to persuase for this design
Can anyone guide be a little bit, or at least point me to the correct direction so i can find some more information?

Ok i understand that we need to use mach3, which uses a parallel port, so a parallel interface must be purchased for the computer. I have seen that on the buildlog pcb the steppers are connected directly on the pcb, and i have seen on random conversations (like the one on the previous post), that some get their own drivers etc, but how are these connected? Also again from random conversations it seems to me that the belt pulleys and gearings doesn't matter (as far as you are doing something sensible of course), and you can set all the ratios via software (but which software? mach3?).

If anyone can write a small paragraph suggesting hardware, or some up to date general instructions, i would be eternally grateful. I dont need everything, i just need enough information to have a grasp before a spend a full week trying to undestand it in depth.

Kind regards
george
 
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Re: building a laser cutter

Postby Techgraphix » Tue Oct 16, 2018 9:47 am

george wrote:Ok i understand that we need to use mach3,

I made several lasermachines which all perform excellent.. using Mach3 is not a very good idea to drive a good performing laser IMHO... it can be possible but there are quite a few drawbacks..
If you don't want to use Mach3 illegal (ie using a pirated copy) you have to pay for it. I thought the price is about the same as you have to pay for a decent lasercontroller like a Trocen AWC708C-lite which sells for around 225$
This controller has plenty of settings to make it a fine machine.. All sensors can be supplied and connected to it, you can communicate using Ethernet etc etc..
What you need is:
Steppermotors or even better closed-loop steppers/servo's for X and Y.. I prefer using the 2Nm hybrid-steppers from Leadshine, like the HB507 with the appropriate motors (2Nm)… these sell for approximate 150$ a set.. Not the cheapest solution but i guarantee that you won't regret that investment..
For the Z (lifting table) i use a normal stepper as loosing steps is not relevant.. it just goes up till the focussensor triggers.. (or down when you push de down-button on the controller)
The steppers drive the belts direct, where the gears have a circumference of 50-100mm. A 40-tooth GT2-10 will drive the laserhead 80mm per rotation which is fine for X-movement
As the Y has to drive the bridge on both sides, a reduction for the Y-motor is fine. Normaly a 1:2 reduction is more than enough.
Make the internal structure rigid. Make it so that you can adjust it to be perpendicular and smooth running.
To give you some inspiration:
CX3C0808.JPG


Kees
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Re: building a laser cutter

Postby george » Wed Oct 17, 2018 1:12 pm

Hello.
First of all, thank you so much for the information. Also my congratulation for this machine, it looks phenomenal. Also it seems like you have done pretty the same design points that i want to implement.
You are absolutely correct. From the time that i sent my first post i continued reading and educating myself about the subject and yes mach3 doesn't cut it. I mean, yes you can use it, using 20 different workarounds to simulate the laser firing and whatever, inability to use raster, etc etc.
So, i have started collaborating with the original poster of this thread, because, as it turns out is on from the same country as me, and the conversations that we had were more than enlightening.
So we pretty much decided to do the things that you suggested since your machine is clearly production level, and we plan to do the same. We are going to use the hybrid closed loop Leadshines for x and y, and a normal stepper for z.
also AWC708C looks absolutely fantastic

i suppose this is the stepper and driver combo that you are using?
https://www.aliexpress.com/item/Free-Sh ... c11a5a82f5

Of course i know that i will have other questions, but instead of wasting your time i need to delve a little a more to the design.

Once again thank you very very much. We appreciate the help.
George
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