A different kind of build.

[FlyinFlynn]

So...for those that might be interested....I am going to build another laser engraver/cutter. This one is a minimalistic design, using just two aluminium extrusions and two Nema17 stepper motors, it must be the most cost effective laser cutter out there - although I am going to have to source all the parts individually and not just order a kit. On the plus side all the parts are commonly available as they are all reprap parts (3D printer)...speaking of 3D printers, all the plastics are printable or millable from the files I have designed and can supply (milling will involve a bit of work removing the chamfers from the holes and chamfering afterwards!). I have also designed the electronics board layout and have ordered a small quantity of boards so a limited number of those will be available if required or perhaps a cheaper option would be for me to supply the gerber files and for you to send them to JLCPCB and order your own for as little as $3 for 5 boards for your first order. The board uses an Arduino nano clone and a couple of A4988 stepper motor drivers. I have added a 5v to 3v3 bi-directional level changer in the PCB design because the specs for the laser I used stipulated the PWM signal at 3v3...not 5v that the nano outputs, I am not sure how critical that is but for the cost of the level changer it was not worth risking the laser.If you can use a soldering iron at all and have a small tip for it the assembly of the electronics board should present no problems. So here is a picture of the design I put together in 123DDesign.

It is based on a picture of a commercial Chinese design... I must say I did get a kick out of ripping off a Chinese design . I can supply the STL's or if you prefer to be able to modify the files I can supply the design files in either .123dx or .sat (for those that use 360Fusion) or even .x3d.
The whole shebang runs off a single 12v 3A power supply and a serial connection. I use the excellent free LaserGRBL to send the .cnc file to the cutter but there are other utilities that can do the same.... You will need to sort out your own CAD package though.. I use Vectric Aspire and tweak the output so suit a laser cutter...again...not rocket science..I know many of you use LightBurn, which is lovely to use but as I already had Aspire........If you get stuck pm me.
My version has a platen size of 270mm x 270mm but any size can be built within reason, you just need longer extrusions and a longer gt2 belt.. a rough costing of the materials comes in at ~£100including the 6 Watt laser module...or you can buy the 3.5Watt kit from China that I ripped off for ~$137...providing you escape the import charges!

If there is any interest I will document the build..

Edited By FlyinFlynn on 29/11/2019 23:34:43

[Richard Marklew 1]

Hi FlyinFlynn

A build log would be great. I want to build a Laser cutter and this sounds just the job!

Thanks,

Richard.

[Fun Flyer]

Go for it!!

[FlyinFlynn]

OK...well I hope there will be some more interested parties as we get into this.

I guess first off the most important thing is the BoM.

Here is a PROVISIONAL Bill of Materials

laser module £31
nema17 x 2 £14
psu £2
GT2 belt 2M £2
2020 extrusion ( mine will be 40cm) £4.00
2040 extrusion (mine will be 120cm) £16.20
Nano £2
A4988 x2 £2
PCB £2
100uF caps x2 £1
headers £2
rollers x7 £6
GT2 pulley 20 t 5mm hole x2 £2
GT Idler 20t 5mm hole 1 off £1


Machine screw-CSK 6x15mm 4 off legs to x axis
Machine Screw pan head 3x12mm 6 off + washers Y axis motor & laser
Machine Screw pan head 3x30mm 6 off + washers X axis motor
Machine Screw pan head 3x20mm + nyloc nut 1 off laser carriage adjustment
Machine screw pan head 3x15mm +nut 1 off X axis adjustment
Machine Screw CSK 5x40 5 off upper & lower frames
Machine ScrewCSK 5x25 5 off x axis adjusters & laser carriage
Machine Screw CSK 5x30 1 off Y axis idler
Nuts plain 5mm 31off
washers M3 8 off
washers M5 3 off
washers M6 4 off

self tappers 2.5 x 10 4 off pcb mounting
M5 or M4 captive T nuts and hex head bolts for extrusion 8 off..some will need trimming down
lever microswitches 2off
Mains lead
assorted bits of wire and connectors

--more--

Edited By FlyinFlynn on 01/12/2019 14:20:45

[FlyinFlynn]

Total cost...around £80 plus whatever the postage costs are. As most of these items come from China you can either get them for next to nothing carriage and wait over a month for them or pay a couple of $$ and get them in 20 days.

The next thing to state is you are going to need access to a 3D printer or a cnc router for the plastic parts. Most of the parts are flat plate and the two exception parts to that can be made flat if you use stand off pillers for one and a commercial offering for the other. A flat upper frame will need 19mm standoffs and the laser carrier could be replaced with one of these speaking of laser carrier, I built mine using one of these lasers I chose the 6Watt version (it is currently on offer at $37.57 delivered 20 day service). This site also has on offer the design ripped off! If you choose a different laser you will have to modify the designs to accommodate your choice of laser module.

Although the seller claims this to be a 6Watt laser I am not convinced. I have not taken any definitive readings, partly due to the laser diode being buried in the module, I could see what the whole module draws but that wont mean much as there are losses in the fan and the electronics. I doubt this is much different than a 3.5Watt laser whose performance has been reported by people, I get about the same results...100% power and 1500mm/min cuts about 1/2mm per pass on balsa. The important thing to remember is the price though...$40 delivered. (HM Customs allowing!)

Not all NEMA17 motors were created equal!... however, as this thing will not be subjected to high loads even the most weedy motors will suffice. I used the 38mm tall versions (42x42x38), the 34mm tall versions would also be fine but if you went for a taller version you will need to increase the height of the legs.

The power supply is non critical, providing it is 12Vdc and close to or above 3Amps (or 36Watts) I used one of these. The usual caveats apply with mains driven PSU's and these are not particularly child safe so if that is a concern for you then choose one of the fully enclosed varieties. I find them less reliable but you pays yer money......etc.

GT2 6mm wide belt available everywhere, the length depends on what size you want to build this thing You will need one piece the length of the 2040 gantry (X axis) plus 20cms and one piece twice the length of the 2020 gantry (Y axis) plus 20cms.

Aluminium profile available from oozenest in the Uk (as recommended by Andy Meade)

[FlyinFlynn]

The arduino Nano, the A4988's, the PCB, the capacitors and the headers are only going to be needed if you want to build one of the controller boards I will supply the details to..if you want to use a commercially available controller board there are loads to choose from..the eleksmaker mana is a good contender but you will have to sort out it's mounting yourself. Also please note the laser I recommend stipulates a 3.3V PWM signal and I make provision for that in my PCB layout. I cannot say what the mana PWM signal is as I do not posses such a board, Whilst I doubt a 5V signal be detrimenal to the laser I am not sure of it...I just decided to fit the level changer board in my design as it was under a euro.

The rollers or wheels need to be the SOLID V SLOT wheels of 24mm diameter - not the V'd out wheels as the wheels hold the gt2 belt in the gantry slot. (If you go for the commercial laser carrier then you will need 3 wheels less and it doesn't matter that the commercial plate uses smaller wheels)

You can either use 3x GT2 pulleys or two gt2 pulleys and one gt2 idler. The pulleys must be 20 tooth, the idler could be less. I used 3x 20 tooth pulleys but the idler would be better engineering, having the idler running on a ballrace and not just spinning on a 5mm thread!

Nuts and Bolts...I tend to buy the longest of each type and cut down the shorter ones, mainly due to the price of the small bags of hardware these days...pay attention top the head type and measure countersunk machine screws from the top of the head to the end of the thread, all other types are measured from the bottom of the head to the end of the thread.

the captive T nuts I used are this type. a couple will need filing down to slip over the gt2 belt.

The microswitchs are the 16mm lever type. Only needed if you want homing on your laser.

OK... that's about it for now

[FlyinFlynn]

So....lets begin!...this is what we are aiming for...

Anybody else think I need to credit Gene Roddenberry?

First off I printed the laser carriage and the X axis feet and foot pads..

I used different colours but only because I have more than one 3d printer. The pads are an interference fit onto the
bottom of the legs but feel free to cyano them on if you want to. The holes in the pads are to screw your cutter down
to a base board if you want to - keep the holes on the outside! You will need to cut a thread in the ends of the 2040
extrusion or have the shop you buy it from do that for you...I threaded mine 6mm after drilling out the ends to 5.5mm
(shop charges are quite steep). You are then ready to bolt the feet to the gantry using (in my case) 6x20 CSK, you can
use any other head you have if you want to.

Here is my 1.2M X axis.

Next up was the laser carriage. After cleaning the print (you always have to drill out the holes to the correct size,
remove any support structure and possibly clean up the 'elephants foot'.....anybody with a 3d printer will know what
that is!).

Fit the adjustment screw and the nyloc nut, you will probably have to apply a little heat to the nut while pressing it
home...use your soldering iron...this is quite normal.Fit the three M5x30 csk machine screws, followed by a nut
tightened onto the plastic, add another nut and nip it up, fit a wheel followed by another nut. Tighten this up and
check the wheel freely rotates.

You may need to fit the M3x10 laser holding screws before the top two wheels as they wont quite clear the wheels when
inserting them into the laser carriage. Once all tightened up (dont overdo it...it is made of plastic!) the carriage
can be slotted onto the Y axis extrusion and the adjuster nipped up so the carriage slides freely on the extrusion but
without any play. dont do what I did and fit the laser just yet..you need free access to fit the toothed belt.

The files to print these items are available here at Stage 1

I have provided .123dx for use in 123DDesign and .sat for use, I believe, in Fusion360. I have done it this way so you can make tweaks to the design should you want to before making the stl's for your printer

[Richard Marklew 1]

Hi FlyinFinn,

Looks great. Unfortunately the link to Stage1 does not work - any chance you could have a look?

Thanks,

Richard.

[FlyinFlynn]

Hi Richard...yes...I have just spotted the problem..a superflous 1 at the end of the link....try

https://drive.google.com/open?id=1AJedeNNfWUQBARRUg_CZH4xR5D4AP1_v

[Richard Marklew 1]

Brill, thanks.

[Chris Bott - Moderator]

Hi FF, I really like the look of this and may well have a go.

I'll certainly be following closely.

For the 3.3v signal to the laser, could you use a 3.3v Arduino Nano? Or does something else need a 5v signal?

[FlyinFlynn]

Posted by Chris Bott - Moderator on 02/12/2019 18:39:06:

Hi FF, I really like the look of this and may well have a go.

I'll certainly be following closely.

For the 3.3v signal to the laser, could you use a 3.3v Arduino Nano? Or does something else need a 5v signal?

Glad to have you along Chris.

There could well be a problem there... I am not aware of a 3.3v version being available. There is a 3.3v version of the mini pro but as this project needs a serial port you cant use one of those. Also the A4988 stepper drivers connect to the +5v output from the arduino (as well as the 12v which supplies current to the stepper motors). You might also run into stability problems because the 328p processor isn't specced to run at 16MHz on 3.3v...On top of that the bidirectional level changers cost under a quid for 5 on ebay!!

You can see the circuit is quite simple really, although the circuit diagram does not quite tie up with that layout as I have added a 'belt and braces' pull down resistor to the PWM signal line to ensure the laser does not come on while the processor is booting in the layout but it is not in the circuit diagram....something I understand the eleksmaker board is prone to do. If anyone with the eleksmaker board has experience of this there is a simple fix requiring soldering a 1K resistor between the PWM pin and ground.

[FlyinFlynn]

OK..re-written the diagrams and re-uploaded them

[FlyinFlynn]

In the provisional BoM I listed Machine Screw-CSK M5x40 5 off. 40mm is just a tad too short so best go for M5x45's

The upper frame is printed next,

Once cleaned up the upper assembly needs to be constructed in this order. Fit the two M5x10 csk machine screws and drop-in nuts, leave then loose. fit the two end M5x45 CSK machine screws with a locking nut.

Then fit the Y axis extrusion....it will be tight but carefully wiggle it in...you don't want to crack the sides. Align the end with the end of the upper frame side supports and then tighten the two securing screws on the bottom.

Now is the time to fit the Y axis stepper motor and 20 tooth GT2 pulley.

Fit the pulley so the width of the teeth matches the groove in the extrusion.

Ensure the orientation of the motor places the wires (or in my case the connector) at the rear of the assembly

Next we need the Y axis belt tensioner, the laser carriage clamps and the Y axis limit switch plate

[14]Assemble the Y axis belt tension adjuster, the plastic part is countersunk but I didn't have a csk M5 so I used a M5x30 cap head, the assembly order was bolt head,washer, gt2 12 (or 20) tooth pulley with the grub screws removed,two more washers, a nut,the plastic part followed by a plain locking nut. Ensure the pulley revolves freely.If you have a proper idler instead of the pulley that's fine..the ball race will do a better job than the aluminium pulley rotating on a machine thread.

Fit the tensioner into the X axis bottom groove,ensuring the teeth of the pulley/idler line up with the grooves in the extrusion. Clamp one end of the gt2 belt to the laser carriage using one of the clamps, the teeth of the belt face outwards and is trapped by the clamp, then thread the gt2 cable into the extrusion groove, between the upper frame and the extrusion, around the motor pulley, back between the extrusion and the upper frame and up the rear side of the extrusion, around the tension adjuster and back to the laser carriage. Fix the belt with the other clamp so that the belt is reasonably loose as the tensioner can be slid outwards to provide the correct tension on the belt.

And there we have the Y axis. there is a lot of spare belt in the pics because this Y axis is not my final Y axis..I borrowed this 2020 extrusion until the slow boat from China arrives so I cut the belt for the proper Y axis which will be 10cms longer. Once you have fitted the belt the laser can be fitted.

The printed part files are available in Stage 2

[Richard Marklew 1]

Looking good FF! I will probably start mine after Xmas and learn from you

Richard.

[FlyinFlynn]

This build blog should be done by then Richard...

On to the lower frame

Once cleaned up

It is now ready for the three M5x45 CSK bolts and nuts to secure, followed by the X axis motor and 20 tooth GT2 pulley
as shown.

Next we are going to need the X axis belt tensioning assemblies

Once cleaned up

you can fit the adjustment nut in the half with the cutout ready for it, judicious use of soldering iron will be
required but don't melt the whole thing!

you need to add one washer to each of the nut cutouts, for that you will need the right sized washers and a little
coaxing with a soldering iron.

you can also fit two rollers at this stage - they are a tight fit so a little easing with a file may be required but
dont over do it. Also of note is that there is a loose spacer between the two ballraces in the wheel, if you can't get
the M5x25 CSK bolt through use a screwdriver from the open side to tease the spacer into place. Use the soldering iron
on the M5 nut if you don't want to risk splitting the plastic

 

 

 

Edited By FlyinFlynn on 04/12/2019 11:53:33

[FlyinFlynn]

This is going to hold me up. I am awaiting parts from China and the postal services are threatening strike action
I may have to cannibalise parts.

Place the two adjuster halves on the lower assembly machine screws. The rollers point inwards as per the photo. It
doesn't matter which side the adjustment screw is on, fit a nut on each screw, tighten the nuts on top of the
adjusters to remove play but still allow the adjusters to rotate

Next fit another nut on each of the three lower frame screws,followed by two wheels on the two inner screws, followed
by a further two nuts on each of the wheeled screws. Don't tighten them at this stage. This is now ready to fit onto
the upper frame

 

If your nuts are 5mm nuts are 4mm thick you should have around 25mm between the two frames, use the free nut on the
rear screw to set the gap at the back of the frames the same and lock them up followed by the nuts that fit on the last
two screws

sorry...that M5 screw should not be in the picture...I only placed it there so as not to loose it. It is the X carriage limit switch actuator....fitted later.

 

When printing these parts the Y assembly adjusters should be orientated with the back face flat on the build plate
with the arms sticking up, that will minimise the support structure. I used 30% infill for the adjusters and 20% for
everything else but you may have a different preference. All the parts will just fit on a single 200x200 plate if that
is your thing and I have included the complete structure in Stage 3

 

Edited By FlyinFlynn on 04/12/2019 11:53:18

Edited By FlyinFlynn on 04/12/2019 11:59:09

[FlyinFlynn]

The completed assembly can now be fitted to the X gantry. First trap the X axis belt in the rear slot of the X axis using a filed down drop in M5 nut and an M5 screw

Then form a loop in the belt and pass this loop between the two fixed wheels and over the X axis pulley.ensuring that the belt is not twisted in the gantry groove.

ensure the tension adjusting screw is fully screwed out and then offer the Y assembly up to the X gantry...It should fit if the adjuster is fully retracted. Once it is on the gantry you can use the adjustment screw to remove all play in the Y axis assembly to X gantry. The correct adjustment will have no play but allow the Y assembly to move freely on the X gantry (you may need to ensure the belt does not bite on the motor pulley for this to happen). Once you are happy the X gantry legs can be fitted, the second X axis belt trap fitted and the belt manually tensioned while tightening the screw.

Adjust the position of the X axis motor pulley so the belt fits in the center of the teeth.
You can now tighten the two middle nuts on the upper and lower frame assembly onto the wheels, there should not be very much room for adjustment so all 4 wheels should all be in the same plane.

Fit one further drop in nut and M5 screw as an actuator post for the X rail home switch.

There it is! The mechanical assembly is complete.

I can add the details of the controller board assembly and loading of the firmware if anyone is interested.

[Nigel R]

watching with interest here flynn

no experience with 3d printers or CNC here so will be just following along quietly - keep it up

[FlyinFlynn]

Arrr...you don't know what you are missing Nigel! The hours that can (and are) whiled away messing about with both of those.......

I've added a YouTube video of the cutter cutting a fuselage side out of a sheet of 3mm balsa...Click here And that is another way of using up your free time....video editing!

[FlyinFlynn]

Looking into the specs of the 6Watt laser I have been using, I found that the 6Watt version is now out of production, presumably why it was available from a number of sources. It was manufactured by a company called NeJe. They still do, however, a 7Watt version which has a laser input power of 2.5Watts, although NEJE's own figures don't really add up

. According to their input power graph the power to the laser module is 710mA@12V at 100% PWM.. that is 8.52 Watts.

According to the bullet point sales blurb it claims the input power is approx 750mA @12V, which does not include the power to the fan...that's 9 Watts.

Anyhow....glossing over the apparent anomaly, the actual laser diode used in their 7 Watt laser assembly would appear to be a 2.5 Watt diode, meaning the actual laser diode used in their now obsolete 6 Watt laser assembly is probably the same or marginally less.

The figures would suggest the diode used in their 20 Watt laser assembly would be a 5.5 Watt laser diode.

I hope that helps if you are looking into buying a laser module.

[adrian garnham]

I have decided to go ahead and build a cantilevered laser cutter along similar lines to this thread.

I have purchased all the mechanical parts and adapted the design to suit my 3d printer which has a max bed size of 120mm cube.

Do you think this laser would be suitable for cutting up to 3mm birch ply https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F123988343347

Any advice would be much appreciated

[FlyinFlynn]

Brilliant!... glad someone found the design useful.

It should cut 6mm birch ply ok.. but it will require several passes and possibly an air assist to blow away the smoke and debris. Not all birch ply's were created equal and the composition of the glues and the density of the wood will have a marked affect on the cutting performance...good luck!

[Erfolg]

Now this does strike me as a RCM&E project, where the Engineering has been put back into the title. What, the E is for electronics, well I never. What ever this project is very much in keeping with the 21st Century, model making environment.

I suspect that there will be some electronics and coding and so forth coming a little later.

I have been considering buying a laser cutter for some time now. The problem with what I have seen is that the bed size has been chosen for a wide range of sheet size, whereas, I really would be happy with a 48" * 12" bed or similar to cut balsa and the light ply type sheets we tend to principally use.

[FlyinFlynn]

Yes...the E started dying out when they started making the components too darn small.....and there will be precious little coding!...Some clever boffin has already written the code...all we need to do is upload it.

I could go into the electronics I used for this project if there is interest, it is quite simple really.

There are loads of commercial kits available that are around A3 size - some less. Some forum members have enlarged their commercial kit laser cutters after finding that they wanted to group items together on larger sheets, that is not my personal preference as I prefer to cut them one at a time so a smaller working bed is fine for me.

The subject of this thread is about a laser cutter that can easily be made to almost any size...just buy different length extrusions! My first build of this design has a working area of 250x270mm and the second iteration has a working area of 1020x150mm