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Andy J
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Everything posted by Andy J
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A possible explanation as to cutting small shapes against larger is that I am using M4 to turn the laser on against M3. Unfortunately using M3 tends to result in burn marks close to a node. So is there any way of accelerating the laser ramp up to the max power level when using M4?
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Will do some further experiments in the cutting height as it is taking in excess of 5 cuts just to get 50%-60% through 2mm hard balsa at a speed of 2000mm/min when cutting a ~6cm rib chord. Strangely a star shape 1cm across cuts 100% through the same balsa in 3 passes using the same speed. So unclear why this should be other than the cutting area is a lot smaller and possibly the average speed between all the cutting nodes is lower. Do agree with your comment on focus Flynn. Is there a simple trick to establish the optimum setting?
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Does anyone have any recommendations as to the flow rate for air assist? Edited By Andy Joyce on 01/01/2020 17:44:08
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Back in business, so can start cutting some ribs now at long last.
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Well have ordered a constant current regulator but tempted just to try my lab PSU to allow simple adjustment of the laser drive voltage and max current.
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Posted by FlyinFlynn on 17/12/2019 13:06:49: The biggest problem with using a third party regulator is knowing the maximum rating of your laser diode. Unless the model number is stamped on the diode and you can find the diode spec sheet, the only thing you can do is measure the voltage that the existing regulator pushes out and set any new regulator to that or just a smidge under that. The one you linked would do the job once you have deciphered the connector designations, but it is a big lump and I personally would go for one of these for the regulator 12V in and regulated voltage out, a single pot to set the required voltage, a decent inductor for spike suppression as laser diodes do not like transient spikes. The output pads are wired to the input connectors of this Which provides PWM control. The laser diode is connected to the output block, the input signal and GND from your arduino goes to the J1 pads. You would also need to provide the 12V to the fan on the laser (check it is a 12v fan first). In the picture of the regulator you linked there is some form of processor in the middle, I can only guess as to its function. Perhaps, as the specs specify 150kHz frequency it modulates the laser power at 150kHz for the duration of the incoming PWM pulse from your arduino ....anybody know? I do know that the laser diode works well using just these two modules as I had one working with a nichia NUBM08. Flynn, what was the source of the constant current regulator you pictured as mine seems to have now given up the ghost and only firing the laser in brief pulses?
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Well finally got an operating switch to modulate the laser by inserting an dual gate MOSFET pcb in line with the old laser output as pictured. However I do find it difficult to find an optimum setting for cutting 2mm balsa. Tried moving the balsa close to the cutter and re-focusing for that distance but it seems I get far better results with the work about 10cm from the lens. So is there an optimum distance for the these types of lasers? Currently using 2000mm/sec 100% power and 3 cuts to go through 2mm.
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PM sent
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Is timing belt supplied as a standard pitch? Ooznest seem to stock GT2, 2.5 & 3 belts so a little confused.
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Thanks Ray Have seen the outline specs before but not the construction methods Miles used. Are there any pictures of his construction methods in your book? Andy
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Thanks to all, will have to read up on the history of the sparrowhawk and see if Peters site can help at all as Ray suggested the wing design came from a Hawk Major.
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Got a Phillip Kent plan, which suggests from measurements taken off the plan that the center section is a NACA0018 going down to a NACA0013 at the tip but just wanted to check that this was true to scale.
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Would any know what airfoil Miles used for the Sparrowhawk?
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Trust we are all still in the land of the living. Still waiting to start my radio therapy 5 months after starting on the hormone treatment but think I should go for the initial scans sometime in January. Night sweets and urgency to pee during the night have caused minor issues, but now on tamsulosin which seems to be doing its job. Trust all keep well over Christmas!
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Jason...try this file in inkscape : File This is the first time I have used google drive so hope the link works. Edited By Andy Joyce on 20/12/2019 15:23:16 Edited By Andy Joyce on 20/12/2019 15:27:07
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Any preference as to regards the profile?
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Thanks Flynn, think this MOSFET switch I ordered is on a horse and cart for delivery as it is showing the end of the month despite only coming from Manchester. Jason... if you let me know what wing profile and chord you need I can see if I can generate one in profili for you and then I will export it to Inkscape which will allow you to modify if required and generate a gcode file. Its all good practice for me, as there is a steep learning curve generating cutting files as you will quickly find out.
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No, when On and set for full power the +ve supply to the diode sits at +5.93v wrt gnd and the -ve supply to the diode sits at +1.55V wrt grnd. So there is 4.38V across the diode. For me that would suggest the MOSFET switch is not operating correctly as would have expected the -ve pin to go close to zero.
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Well the voltage applied to the laser is not quite as I expected. More o/p power seems to be applied by lower the voltage on the -ve rail so increasing the voltage across the diode. Withe laser enabled and set to max power the +ve supply wrt 0v grnd is 5.93v & the -v pin is 1.55V wrt 0v grnd. With the the laser turned off both pins go to 5.62V wrt 0v grnd.
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Have purchased a MOSFET switch as illustrated so will try that first before I completely exchange the control board.
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Alex, Could I not just to use the existing regulator PCB and route the laser diode output through the dual MOSFET switch that you suggested and divert the TTL/A signal to that board? Still waiting to hear if I can return the laser as that is probably my best option rather then trying to make the existing PCB work that came with the device. Edited By Andy Joyce on 17/12/2019 19:35:18
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