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Cheap Chinese Laser Cutter

experiences with a Chinese laser cutter

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Barrie Lever08/04/2020 12:46:36
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175 forum posts
41 photos

Stephen

The head was on the machine when I bought it, I imported the machine direct from Flash Laser ordered through Alibaba

http://www.flashlasercnc.com/

Regards

Barrie

Edited By Barrie Lever on 08/04/2020 13:14:48

Martyn K08/04/2020 19:53:57
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5079 forum posts
3678 photos

Thanks for the advice.

The settings on the controller are:

$30=1000

$31=0

$32=1

which I think is correct.

I also fail to understand why the laser only appears to be running at about half power

I have also grouped the object so all the arcs should now be contiguous.

Any thoughts?

Martyn

Martyn K08/04/2020 20:51:17
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5079 forum posts
3678 photos

I have tried setting $32=0 - that gave me back my power but the cut path still stuttered in the same places. So now its back to $32=1 and reduced power again. The main wheel circle - which is definitely one object also stutters.

I still think this is a controller issue struggling to process commands in a timely manner.

So, starting from scratch, using the little drawing package in Lightburn, I drew a random shape of a square overlapped by a circle with a few random lines (scribble) intersecting the square and circle.

It worked perfectly, I had full power back (or it appears to be), no stuttering and nice clean cuts. The only gaps were at the corners where the power reduced as it slowed down.

So, is the problem the way that the program is interpreting the DXF file and generating GCODE?

I will get to the bottom of this...

Martyn

Barrie Lever08/04/2020 22:15:41
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175 forum posts
41 photos

Martyn

How sure are you that in the wheel spat file that all of the lines meet up, I know you said they are grouped together but in some CAD software that is no guarantee that everything is linked end to end.

Have you viewed the GCODE to look for irregularities? The code for those parts should not be too complicated.

B.

Stephen Smith 1408/04/2020 22:23:50
208 forum posts

Thanks Barrie will see if I can get there head once the world returns to some normallity but they don't list any parts on there Web site.

I see they supply the same poor exhaust fan, I found one on thingyverse which uses the same motor with a different housing printed in several parts, seals much better on the back of the machine and the difference in performance is night and day.

Martyn K08/04/2020 22:31:11
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5079 forum posts
3678 photos

Hi Barrie

Good question. I am absolutely sure, but I will double check in the morning. The wheel outer stutters and that is definitely a circle.

Martyn

Martyn K09/04/2020 10:39:45
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5079 forum posts
3678 photos

I appear to have a fix after posting my problem on the Lightburn forum

I got a very good suggestion which didn’t work unfortunately, however an explanation of laser mode gave me the clue I needed. I simply dropped the cut speed down from 600mm/min to 300mm/min and it worked perfectly, with nice clean corners.
I also tried with an ai file type and join selected shapes (suggestions from the Lightburn forum) . In fact, the fix may be a combination of all 3 but there was no obvious improvement until I reduced the speed. I need to experiment a little more but the quality of cut now is very much better.

The problem was that the head could not accelerate or decelerate fast enough to keep the laser going at the desired power.

Simple really.

Martyn

Barrie Lever09/04/2020 11:23:37
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175 forum posts
41 photos

Martyn

Good news that you have it sorted.

Carrying the laser itself on the carriage does bring acceleration deacceleration issues, I mentioned that in comparison with a mirror based laser.

I think we have all learned some things in this discussion.

B.

FlyinFlynn09/04/2020 11:35:43
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148 forum posts
95 photos

Barrie - Yes Barrie, I am sure my statement was correct, but I think you misunderstood it.

**LINK** describes it better than I can......operational procedures for mechanical routing and laser cutting are vastly different.

Barrie Lever09/04/2020 11:46:52
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175 forum posts
41 photos

Posted by Stephen Smith 14 on 08/04/2020 12:39:47:

Barrie thats a really nice head on your K40 what make is it and where did you get it from would like one on mine.

Stephen

I have uploaded a couple of detail photo's of the final mirror assembly, maybe you can modify another assembly?

BarrieFlashlaser K40 detail 2Flashlaser K40 detail 1

Barrie Lever09/04/2020 12:15:22
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175 forum posts
41 photos
Posted by FlyinFlynn on 09/04/2020 11:35:43:

Barrie - Yes Barrie, I am sure my statement was correct, but I think you misunderstood it.

**LINK** describes it better than I can......operational procedures for mechanical routing and laser cutting are vastly different.

FF

Are you sure the operational procedures are vastly different? I see them as near identical !!

Here is some code for a 100mm square on a laser cutter

( PROGRAM NUMBER: 0100 )
( PROGRAM NAME: FF_100MM_SQ.TAP )
( POST: FLASH LASER K40 )
( DATE: THU. 04/09/2020 ,TIME: 11:51AM )
(Machine Setup - 1-Feature 2 Axis-Profile Rough)

G90 Absolute mode
G17 Arcs in X,Y plane
G21 Metric mode
S1 Laser on once G01 is invoked
G00 X.127 Y-.127 Rapid to this position
G01 Y-99.873 Cutting
X99.873
Y-.127
X.127
S0 Laser off
M2 Home

Here is some code for a 100mm sq on a decent CNC router

(BEGIN PREDATOR NC HEADER)
(MTOOL T1 S1 D1.5 C0. A0. H38.)
(MTOOL T1 S1 D1.5 H38. A0. C0. DIAM_OFFSET 1 = .75)
(SBOX X0. Y0. Z-25.4 L100. W100. H25.4)
(END PREDATOR NC HEADER)

(PROGRAM NAME - FF_100MMSQ.DIN)
(POST - CNC-STEP HIGH-Z S-1000T)
(DATE - THU. 04/09/2020)
(TIME - 12:00PM)
%
G90
G28
G64
(Machine Setup - 1-Feature 2 Axis-Profile Rough)
(FEATURE 2 AXIS)
T1 M66
G79
M03
S21220
G4 H2
G53 Z0
G54
G00 G90 G54 X.75 Y99.25
Z5.08
Z2.54
G01 Z-1. F2375.9329
Y.75
X99.25
Y99.25
X.75
G00 Z5.08
Z15.
M05
G28
M30

There are no special considerations for the laser within the G Code it just gets on and cuts, I might do a video of that code running on the laser cutter.

B.

Jason Channing21/04/2020 21:21:38
149 forum posts

Having read through all the posts im trying to confirm with the Banggood laser cutter what is the most common or best software, I found the Elsmaker not too bad but quite limiting and the Lightburn very complicated to get going. The elsmaker is cutting ok and I can understand what is happening but the Lightburn I dont know where to start.

FlyinFlynn22/04/2020 08:35:16
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148 forum posts
95 photos

Barrie, 100 square square what?

Did you read the explanation I linked? Your examples show only a very simple job performed on cnc router software. Predator is a full blown professional cnc router software suite which pays lip service to laser work with the provision of a laser post processor. Does Predator even have a laser mode?.. I doubt it . The PP may allow you to specify spindle speed changes to, for example, engrave the former numbers on the workpiece, but if you do that you will see the problem of burnt corners manifest itself. You are also using a 40Watt CO2 laser, probably with air assist to help limit smouldering. It is not running GRBL, which is much more suited to this application using low power laser diode heads when cutting and engraving balsa type woods. It is what this thread is about.

As to the procedures for cutting balsa by laser or router, You do not vary the spindle speed all that much on a cnc router, probably only when a tool change occurs, whereas if you are engraving with a laser the spindle speed is changing all the time, without the laser mode setting in GRBL the laser motion would pause with every spindle speed change command. I would call that vastly different operational procedures.

Engraving on a cnc spindle router is a very different process than engraving with a laser, the cnc router cuts away material at varying depths usually all at the same spindle speed whereas a laser varies its intensity to change the amount of charring of the wood all in one plane....very different processes.

FlyinFlynn22/04/2020 08:56:20
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148 forum posts
95 photos
Posted by Jason Channing on 21/04/2020 21:21:38:

I dont know where to start.

Jason - there is no 'best' software, only personal preferences. You can think of software for producing ribs, formers and stuff as being divided into two camps, CAD and CAM. The CAM part is quite easy to come by and eleksmaker does an OK job at that but CAD is a different story. Eleksmaker is very limiting and Lightburn is more complicated but much more functional in that regard. There are others, but any CAD software worth its salt will not be free, at least I haven't found one, and it will probably be more complicated than Lightburn because Lightburn is written specifically for laser work whereas other CAD software will be more router based. Many functions for cnc routing are not required for laser work.

So if you are finding Lightburn too complicated I suggest you keep trying to understand what the options do in Lightburn until the free trial period expires and then make a decision. There is a manual for Lightburn here.

I use Vectric Aspire, 123DDesign, LibreCAD, Deskproto, LaserGRBL and yes Lightburn..... until I was required to pay for it!

Jason Channing22/04/2020 09:27:40
149 forum posts

thanks for the info Flyin, thats what I was after info wise, I will continue with Lightburn and more than likely buy after the trial, My son and I know our way around 3d printers from top to bottom and this is like learning over again.

Barrie Lever22/04/2020 09:35:55
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175 forum posts
41 photos

FF

You are correct in that the thread was really talking about lower power laser diode heads, so we should restrict the discussion fairly shortly to those machines.

However I think you might be misunderstanding how the PP works in a traditional CAM package and I would just like to try and help you understand that process.

In my case the tool paths either laser or cnc router or lathe are all generated by Moduleworks CAM which does have a specific laser mode, where kerf widths among over things are taken into account. In the same way as it considers tool diameter for routing or milling.

I modified an existing post processor (might have been HASS) to give out the G codes that the cheap Chinese laser cutter required. The post processors have no idea about the machine or cutter that that they are providing code for other than to only give the machine the codes or instructions that it can understand, consider the post processor as a dumb translator.

I have no experience of the GBRL, maybe that works very differently, I also have to say that the cheap Chinese laser cutter that I have has the laser either on or off by the software, laser power is varied manually, we do a lot of engraving, and cutting in the same part but the engraving is always at one intensity, if we need two different depths of engraving in the same job (rarely) we run the deeper area with a second engraving pass.

I have Lightburn but do not use it as it does not fit with my work flow. I use either Corallaser or K40 whisperer to control the laser engraver/cutter, with the CAD being developed in a multitude of different CAD packages.

I am afraid I cannot help Jason with his software request as I now see the machine is very different to what I am used to.

A few examples of engraving and cutting done on the K40.

B.

dsc_0583.jpgdsc_1041.jpg

FlyinFlynn22/04/2020 17:30:16
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148 forum posts
95 photos

Thanks Barrie but I am reasonably familiar with what a post processor does and how to make one, I have written a couple for my machines when using a predominantly cnc spindle CAD/CAM software without 'proper' laser support.

To my mind making multiple passes to vary the burn when laser engraving is only done in the Preditor suite because it uses exactly the same process for cnc spindle engraving, so you may see cnc spindle and laser processes as the same, however it is not be most elegant solution as you will need multiple passes and will possibly still get burns in the corners as the laser carriage is stationary and the laser is delivering its energy onto one spot on the workpiece.
It may be that a CO2 laser can spend less time stationary at a corner due to the lower mass on the carriage, but as we are talking low power laser modules here the problem is very pronounced.

So the long and the short of it is you are talking about a totally different animal, cnc milling for the (semi) professional where the software writers are not going to materially re-write their software for the 'maker' laser community and will just write a PP to deal with the worst problems that running a laser instead of a mill brings.

GRBL, which is specifically aimed at the 'maker' community and not at the (semi) professional community, deals with laser operations in a different way to the cnc milling environment. The CAD/CAM software I sometimes use, Vetric Aspire, was developed purely with cnc milling in mind, with only a recent nod to laser operations by the users publishing a PP for laser use - that too is a fudge to get your .nc processed.

It may not fit your workflow but I suspect LightBurn would do a 'better' job, with laser specific functions, than your milling software could achieve, and it is a lot easier to get your head around.

Barrie Lever22/04/2020 18:06:32
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175 forum posts
41 photos

FF

Thanks for the explanation of GBRL, I mentioned very early on that I could see the mass being carried in the LED laser head.

The Co2 laser with mirrors is very low mass and the Austrian Trotec's are literally a blur when engraving, I think way over 1000mm sec.

With K40 Whisperer control which uses G code I get what I am used to seeing which is a bunch of G codes and I am very comfortable with that high level of control.

We very rarely do double depth engraving but have no choice to do repeated pass's because the laser intensity is not software controlled on a K40 when using the original Chinese controller.

I have attached some screen shots of what I have in CAM when programming the laser cutter.

Regards

B.

laser screen 1.jpg

laser screen 2.jpg

Jason Channing25/04/2020 21:18:08
149 forum posts

I have the 3500 mw Bangood cutter and am using light burn. I have lots of data recorded for speeds and wood density and thickness for balsa wood and can get beautiful cuts through the softer 1/16" 1/8" and 3/32" but when i go to cut the harder density balsa if it does cut though it is too burnt and am using 5 passes, have played around with speeds and % of power but not getting a great cut through harder 1/8 with too much charring, any ideas where to start in relation to speeds, power setting and passes etc. looking for set up tips for 1/16 ply and balsa and guidance . thanks.

FlyinFlynn26/04/2020 11:46:00
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148 forum posts
95 photos

Can't really help with settings for harder woods Jason, but I think it will all come down to how much energy you can get focused onto the cut line. Perhaps an air pump clearing away any smoke will have tangible benefits, getting a proper focus will help too.

If 3.5Watts isn't going to do the business perhaps the best solution is just using the laser to accurately mark the wood for cutting out on a band saw ( or Stanley knife in the case of the really thin ply)

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