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Mach4 General Discussion / Re: Mach4 Printer Port Discussions
« on: June 17, 2014, 08:20:34 AM »
Hi Art,
For the Synrad I use an external tickle pulse generator. It is a very simple circuit and has approx 10% of adjustment for both the frequency and pulse width – this enables it to be set to just below the point of lase. The Mach PWM and the tickle pulse are then switched in or out by a separate trigger circuit (diagrams attached).
In order to get the best laser versatility (never know what we will want to do tomorrow) I think you need as many different individual levels of power as you can achieve (I believe Synrad use 5% step variation of the duty cycle between 0% and 95%).
You will have to be careful if operating the Synrad above the recommended 5kHz PRF – for example at 20kHz then a 95% duty cycle will exceed the maximum recommended internal photon density for the tube (overheating the output coupler and / or the rear mirror). The Synrad controllers software limit the maximum available duty cycle as PRF is increased thereby negating the problem.
I am no expert here but it is my understanding that the Mach3 engraving plugin allocates a set number of ‘dots’ per each individual pixel value and because for high pixel values the dots overlap each other many times during one X axis scan it produces ‘dot-gain’ and thus a shade of burn in accordance with actual pixel value. In my opinion this process works extremely well and I think I am able to get results that are up there with the professional laser systems. Overall the engraving plugin is going to take a lot to better but you are the expert and I am really looking forward to trying the Mk II.
On the other side of the coin those using diode lasers have found that DC variation in actual laser output power level in accordance with pixel value is the way to go.
I can actually do this with my DC excited laser but I still prefer to vary the output power level by varying the PWM in the same way as the Synrad is controlled.
Tweakie.
For the Synrad I use an external tickle pulse generator. It is a very simple circuit and has approx 10% of adjustment for both the frequency and pulse width – this enables it to be set to just below the point of lase. The Mach PWM and the tickle pulse are then switched in or out by a separate trigger circuit (diagrams attached).
In order to get the best laser versatility (never know what we will want to do tomorrow) I think you need as many different individual levels of power as you can achieve (I believe Synrad use 5% step variation of the duty cycle between 0% and 95%).
You will have to be careful if operating the Synrad above the recommended 5kHz PRF – for example at 20kHz then a 95% duty cycle will exceed the maximum recommended internal photon density for the tube (overheating the output coupler and / or the rear mirror). The Synrad controllers software limit the maximum available duty cycle as PRF is increased thereby negating the problem.
I am no expert here but it is my understanding that the Mach3 engraving plugin allocates a set number of ‘dots’ per each individual pixel value and because for high pixel values the dots overlap each other many times during one X axis scan it produces ‘dot-gain’ and thus a shade of burn in accordance with actual pixel value. In my opinion this process works extremely well and I think I am able to get results that are up there with the professional laser systems. Overall the engraving plugin is going to take a lot to better but you are the expert and I am really looking forward to trying the Mk II.
On the other side of the coin those using diode lasers have found that DC variation in actual laser output power level in accordance with pixel value is the way to go.
I can actually do this with my DC excited laser but I still prefer to vary the output power level by varying the PWM in the same way as the Synrad is controlled.
Tweakie.