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Member postings for chris larkins

Here is a list of all the postings chris larkins has made in our forums. Click on a thread name to jump to the thread.

Thread: New EDF Mini Jets- Jet Provost & Folland Gnat
18/06/2020 22:25:18

A few more pics of Dick's lovely Gnat

gnat3.jpg

gnat2.jpg

gnat1.jpg

Thread: S1581 Hawker Nimrod MkI
16/06/2020 23:02:02

Looking forward to you finishing the Apache build Danny, which hopefully will be next up cool

Thread: Silhouette vinyl cutter files sharing
30/12/2019 23:51:13

Not modelling related, but it continues to impress me how the cutter works. I just made this decal to stick on the wallet that contains my daughters car paperwork. Some of the lines are only about 1mm thick but it came out great.

fiat500.jpg

Thread: Which Laser cutter
16/12/2019 19:27:40

I upgraded my laser engraver with a new control board and a 15W laser module, details are on the other thread called 'cheap Chinese laser cutter'.

It will cut 3mm balsa in 1 pass, and 3mm birch ply in 3 passes, total cost with the upgrades which includes air assist was about £250, 650x500 bed area

Thread: Servo voltage question
16/11/2019 18:43:12

Use a 2s LiFe battery, less volatile than a LiPo and the voltage drops to 6.6v once it is off charge

Thread: Cheap Chinese Laser Cutter
08/11/2019 22:26:19

I bought a new controller which was £17.89 with free postage on Amazon, it turned up today and after swapping it over I have success. I did have to add a common ground as described above so the controller and new laser have their own power supply but after that it worked straight away.

The laser is quoted as being 15W, I know that this is impossible and is a wild Chinese claim and is more likely to be about 8W true, however the power increase is very noticeable. It cost me £76 for the new laser so total cost to upgrade with the new controller was £93

I did a test engraving on 3mm birch ply and I'm really happy with the result, I also did a cut and it took just 3 passes to get all the way through at 200mm/min, with my old laser it took over 40 passes in 3mm birch ply.

YouTube link

06/11/2019 17:41:00

I am having trouble connecting my new laser and getting it to work correctly. My control board used 2 wires to connect to the old laser and this worked well & switched the laser on/off as required and fired it up in test mode.

I can't get the new laser working correctly, it is always on unless I hit the reduced power button, I have tried various combinations using the 2 wires from the control board, the nearest I have come to getting it working is in reverse i.e the laser is on when stationary but switches off when it is moving and should be cutting.

Can anyone help?

the bottom 2 pictures are the separate driver board that came with the laser.

control board.jpg

 

connections.jpg

driver board.jpg

Edited By chris larkins on 06/11/2019 17:44:44

06/11/2019 17:32:32

It was £21 inc p&p from eBay so not too bad

06/11/2019 17:03:34

Well my air pump has finally arrived, it is rated at 35 litres per minute. I made up a bent brass tube which directs the air straight at the cut.

pipe.jpg

pump.jpg

05/11/2019 18:05:29

I have finally got around to making the lid for my enclosure, it's made from 5mm foamboard glued with UHU POR and reinforced with white gaffer tape. The window is A3 sized 3mm tinted acrylic. I have tried it and it completely contains the burning smell and the extractor fan vents this outside, happy that making the enclosure was worth it.

I am still waiting for my air pump to arrive, I'm hoping that this will make the cuts much cleaner.

I have also purchased a more powerful laser module which will hopefully be more suited to cutting, just got to figure out how to hook it up as it has different connections, as usual with Chinese stuff there are no instructions either.....

lid.jpg

window.jpg

laser.jpg

01/11/2019 21:16:28

Here is what I have done which seems to work ok, although I have only used it once since.

I used some soft rubber bands which are hooked onto the back and sides of the enclosure, this supports them just about when the laser is close to the back but has enough stretch to allow the laser to move to the front

elastic.jpg

30/10/2019 12:58:27

I have started to make an enclosure to deal with the fumes problem, my machine is 65cm x 50cm but with the extra room required each side for the stepper motors the enclosure ends up being quite big.

For the sides I have used some left over laminate flooring (so I have a nice faux wood finish laugh), I have yet to make the top but I will probably make this from some 5mm foamboard that I have left over from another project which will make it light enough to lift on and off, I have also ordered some A3 sized 3mm orange tinted acrylic to give a 'viewing window'.

In one side I have installed a 100mm extractor fan which I will vent outside, in the back there are a couple of small 20mm holes to allow air to enter.

I am still waiting on my air pump so that I can provide a flow of air to the workpiece, I am thinking to mount some brass tube to the side of the laser module which will direct the airflow, in a similar way to on some scroll saws. The question is how close does this need to be? Does it need to be within a centimetre or so of the workpiece or is an inch or two close enough?

enclosure.jpg

enclosure1.jpg

29/10/2019 16:42:34
Posted by Andy Meade on 27/10/2019 17:22:21:

OK well I calibrated mine myself - 80 steps per mm on X and Y axes, also had to invert the X pin as it was backwards. Just need to figure out how to reset origin 0,0 position now and focus the laser.

Mine was the same, set it to 80 steps and it's working fine now

25/10/2019 21:17:13

Yes I have, when I'm home I'll send you the details of what I did. First off you will need to download the GRBL hex file, just go onto the GRBL website and download it, I think it was version 1.1 

Edited By chris larkins on 25/10/2019 21:18:46

25/10/2019 14:06:23

I am using Lightburn, at first the laser would not cut at all but the smax was set to 255, after changing it to 1000 I was in business. Then whatever I was cutting was coming out WAY bigger than it should have, after searching the web I discovered that the steps were out, after changing the X and Y axis to 80 it was back to the correct scale.

It still took 13 passes at 2700 mm/min, but I guess that is the price for having just a 3000mw laser, maybe slowing it down would reduce the amount of passes.

The plan was a freebie in RCM&E, Peter was kind enough to send me the PDF.

25/10/2019 11:33:32

Success, I did as Robert suggested and tried again but this time raised up on 8mm rails, this time the parts dropped through once cut.

drop cut.jpg

drop final.jpg

25/10/2019 10:52:54

I have a small fan placed about 6 inches away as that's all I have for now, I have ordered a pond pump which I will run through some thin tube so that it's close to the wood. I am using 9mm MDF for the baseboard which is working well so far although I've only done a few cuts.

I was using the thin plastic pieces to raise the wood up, but they are only about 1.5mm thick so perhaps I'll try something thicker, it would be nice for the cut pieces to drop down so that I know I'm all the way through.

On the pictures below I was cutting an F1 former for a Peter Miller 'The Ohmen', it took 13 passes to get all the way through, I am hoping that when the pump arrives it will be a cleaner cut.

Thanks Geoff, I'll try playing with the G-code. I am also using Inkscape and I did download an extension to generate the G-code, however I am not using this and instead I am using Lightburn to control the laser.

VIDEO LINK

f1 final resized.jpg

f1 cut resized.jpg

f1 sheet resized.jpg

24/10/2019 12:56:32

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24/10/2019 12:55:12

Just done my first cut in anger, 3mm balsa, 100% power, 3600 mm/min.

The cut got about 95% through in one pass so next time I might try reducing the power a bit but with 2 passes.

VIDEO LINK

21/10/2019 10:21:44

I assembled mine a few days ago, if you have any questions or want a picture of any specific part let me know.

I have done a few test cuts using the benbox software but I have now downloaded Lightburn for the free 30 day period, it has taken me a while to get it set up on lightburn as you have to flash the firmware on the card, simple enough once I figured out how.

If you have any issues connecting it up on Benbox let me know, it took me several frustrating hours to figure it out

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