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A different kind of build.

A cost effective laser cutter design and build..from scratch

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FlyinFlynn09/12/2019 11:21:42
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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 garnham12/12/2019 10:29:54
17 forum posts

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

FlyinFlynn12/12/2019 11:03:51
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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!

Erfolg12/12/2019 11:15:30
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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.

FlyinFlynn13/12/2019 17:06:37
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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.laugh

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

Max Z14/12/2019 08:29:21
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FF, I have been following your report with interest. I already have access to cnc capacity, so I do not intent to build one for myself, but I like to follow others with an original design, like yours.

I was wondering, with a cantilever type like you have designed, does it not suffer from inaccuracies due to the deflection of the Y-axis beam varying with the travel of the laser head? I don't suppose the beam itself is bending, but more like some flexibility in the X-axis guide system.

Erfolg14/12/2019 17:23:52
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11503 forum posts
1261 photos

Max

Let us assume there is deflection. Which is will also be true of systems built on Portal frames. As Beams bend.

I assume there will be twisting also due to torque effects.

In my brief time in the Machine Tool Industry and additionally in classification of installed machine tools for class of production accuracies, does it matter? What accuracy is required for model parts?

Having been out of manufacturing industry for now 40-50 years, I can remember that some horizontal boring machines had a cantilevered boring head. Radial arm drills obviously were the same. In those cases I guess the manufacturers ensured that the sections and mechanisms were sufficiently rigid under loads.

In my case I just need sufficient performance to match my needs, rather than the accuracy that some applications may demand.

Max Z14/12/2019 17:53:34
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543 forum posts
245 photos

Not so much the accuracy of the cut, but the effect on the focus of the laser and on the efficiency of the burn, and hence the number of passes and the width of burn zone. I have no idea how critical this is, that's why I am asking smiley

FlyinFlynn14/12/2019 19:51:51
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116 forum posts
82 photos

I really cannot see the gantry bending..providing it is not 10 meters long laugh. There is very little extra load on the gantry when the laser moves to its outermost end - and there are no 'loading' loads that you would get with a router that is pushing down on the work piece so.... no..I don't see any degradation of the cut.. Both axes have fine adjustments to get the carriages slop free but 'fluid'. Also, we are in modelling territory here, not precision pcb etching territory. As you go longer in either axis you could start to run into issues with the belts stretching and vibrations caused by lack of sufficient supports, although so far my 1020mm cutter seems ok, and no one would want anything longer surely question

The laser focus is also a bit hit and miss.. it is not that critical, if it was you would have to lower the laser head for every pass as it cuts about half a mm per pass. I find cutting 6mm balsa without adjusting the focus is no problem, of far more use is blowing away the smoke and debris from the cut. TBH if the laser has to do 20 passes instead of 18 on 6mm balsa so what? 6MM ply might be more problematic I suppose, but I think I would use the 2.5Watt laser to mark the piece out and then cut it on my bandsawwink

Erfolg14/12/2019 21:23:53
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11503 forum posts
1261 photos

Flyin, your comments on belt stretch, rekindled memories of the difficulties that the then a local machine tool manufacture encountered. There had been a step change in speeds and feeds, again, if my memory serves me well, due to the introduction of "Coated Carbide" cutting tools.

In conjunction with the digital controls, the much higher traverse and feed rates, stretched the lead screws, causing overshoot, in conjunction with a poor damping characteristic of the negative feed back control system, lead to a lot of hunting. The solution was obvious, but a chancellor who was going to squeeze the rich until the pips squeaked, the company threw in the towel, if the government was going to take the profit, without the risk, with hind sight, I cannot blame them.

All I look for is something that works for me as a modeler, that I can afford and provides a useful tool. Yes there will be limitations and tweaks required.

So keep it up

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