Messages

31

3D Printers / Re: New to lasers and SLA and need some info

« on: March 19, 2018, 11:33:55 PM »

1. Laser power? I'm assuming approx 150 mw would be plenty?

405nm 50mW-150mW lasers seems popular for SLA printers. Would those work? Maybe...
This is a challenging question to answer without other system details. Some of these include:
-accounting for resin cure characteristics
-how fast the laser will be scanned
-beam focus
-beam diameter.
I see you plan to use an f-theta lense and that will help minimize some variable complexities.

2. digital or analogue galvo? I'm assuming analogue, but I haven't done a whole lot of research on how exactly I'll be driving the galvo? Will I need a separate galvo control board in addition to the ramps 1.4 I was planning on using? Can I control it directly from a raspberry pi? Again, totally new to galvos and how they work and all that, so feel free to enlighten me as to the electronics necessary to pull this off.

I suspect they are asking if you need a digital scanning head or analog scanning head vs galvo. If you purchase a digital scanning head I presume it will use the XY2-100 protocol and you will not need a LaserShark (nor will the LaserShark be compatible/make sense). If you purchase an analog scanner head you will need an analog controller board such as the LaserShark but first you will need to determine if the input characteristics of the heads input match. I would expect most things would follow the ILDA standard so this would be true but you would need to confirm this. I do not see analog specifications in the attached document.

3. connecting table? Not even sure what they mean by this, but hopefully someone here knows what they're talking about?

The documents suggest this might be a poor translation and correspond to the mounting interface between the scanning head and laser.

The supplier is a company from alibaba.com and the model they're offering is a Model JD2203 Galvanometer, with a 405nm laser and an f-theta lens lens specifically designed for a 405nm laser and a 300mm x 300mm working area. I'm expecting the total scanning head to come in around $500 or so, which is insanely cheap compared to the other options I've found online from American Suppliers. It's a big enough savings that I'm happy to drop the $500 on one of these scanners and give them a shot. Any feedback or input of any kind would be greatly appreciated since I'm in way over my head on this build.

That is quite low in cost. Generally this is an indicator that R&D costs could be avoided or that the product has been cost-optimized. I would be curious to know the KPPS rating of his scanning head as well as the stability characteristics in comparison other companies around the world.

I'm also trying to figure out exactly HOW all the components will play together. I've been hunting around for some info about what the lasershark board actually does, correct me if I'm wrong, and it looks like it essentially scans an image, line by line, and converts it translates that into movements so the laser will draw the image that is sent (via usb) to the board. So in this instance, it will essentially be working like a DLP Projector. Whatever control software I'm using (would love recomendations for slicers and control software for sla set up) would tell the stepper to move the Z axis up/down, then send an image (rather than a series of gcode commands for all the movements of an FDM printer) to the lasershark board and it will "project" the image onto the resin. Does this mean I could use software designed for DLP printers such as NanoDLP or others if I'm using a lasershark board to control the laser?

The lasershark driver (that runs on your computer) accepts x/y coordinates and power intensities for the laser channels, stuffs these into buffers and sends them over usb to the LaserShark. The lasershark in turn prints out these coordinates at the designated kpps rate you configured the points to be displayed at.

the lasershark_hostapp github repo provides two means to use this:
1. You can use lasersharklib to integrate the lasershark libraries into your codebase and drive the LaserShark as fast as possible
2. You can compile lasershark_stdin and pipe samples in a simple text format into the application. This latter approach is less efficient, but much easier as you do not have to learn how to use libusb/etc.

In this repo are two examples of how to use lasershark_stdin. One is lasershark_stdin_circlemaker. If you pipe this into lasershark_stdin, a circle will be drawn. The other is lasershark_stdin_displayimage which will line-by-line display a png image if you pipe the output into lasershark_stdin.


Your software would need to control the z-stepper motor (i.e. you could write a python app that controls this between layers). If you can get software to present you with a png image of each layer you could theoretically adapt it, but you would need to have some integration glue on and (all of which you should be able to confirm before buying any hardware).

32

3D Printers / Re: LaserShark and Creation Workshop

« on: February 12, 2018, 11:05:16 PM »

If you have a program that can slice a 3d model into layer images, you could make a script based off of using lasershark_stdin_displayimage.c.

33

3D Printers / Re: lasershark_3dp file?

« on: February 10, 2018, 06:14:18 PM »

I am unable to download these files.

Are these your files or someone else's? If the latter, where did you find these links?

34

3D Printers / Re: types of galvo supported by lasershark board for SLA uv printer

« on: February 10, 2018, 01:59:08 PM »

Hi

1. Starting with the ascii interface (lasershark_stdin) is perfectly fine for prototyping, it was intended to allow an easy start for prototyping.
If you send X and Y values, yes, it will make the galvo motors move to those positions. You can read more about the lines that you must send by reviewing the lasershark_hostapp code.

Specifically:
lasershark_stdin_circlemaker
lasershark_stdin_displayimage

And perhaps most useful for learning the protocol:
lasershark_stdin_input_example.txt
This file will tell you the format of commands to send (i.e. how to set rates, move galvos, and turn lasers on/off)

2. The galvo amplifiers require differential analog signals. The differential input voltage provided is what designates what position the galvos move to. A differential value of -10v will make the galvo rotate to it's fullest extent in one direction and a differential value of 10v will make the galvo rotate to it's fullest extent in the other direction. A differential value of 0v will make it move to a centered position.
The amount of rotation will depend on how much you change the voltage from one point to another. In the case of the LaserShark there are 4096 "steps" divided in the case of your galvos by 30 degrees. This means each "step" under ideal circumstances will correspond with a 0.00732421875 degree change. Note that in reality you will never achieve this small/consistent an angle change due to various imperfections related to each component in any galvo system.

3. It will require you to develop software but yes? Others have already done this to varying degrees. Unfortunately their works are closed source

35

3D Printers / Re: lasershark_3dp file?

« on: February 10, 2018, 01:40:01 PM »

Can you please clarify your question? I'm not sure what you are asking for

36

3D Printers / Re: LaserShark and Creation Workshop

« on: February 08, 2018, 12:16:49 AM »

Hi VitoB,

Creation Workshop is software developed by another company (Envision Labs). If you go to their website (www.envisionlabs.com) it suggests everything has moved to a new home (and maybe company?) of DataTree3D.

Have you tried talking with this company?

37

3D Printers / Re: types of galvo supported by lasershark board for SLA uv printer

« on: February 05, 2018, 11:07:49 PM »

Hi

1. Yes, the LaserShark sends signals that can be interpreted by the "galvo drive" (usually referred to as a galvo amplifier) in order to steer the galvanometers.

Galvo amplifiers are analog devices and should not be advertised with a bit rating (i.e. 8bit or 12bit). These values are associated with the galvo controller board that is sometimes shipped as part of the galvo/galvo amplifier kit... and intended for setting up very cheap laser lightshows. You do not need this controller as the LaserShark replaces this component (and is thus a means for you to save money)

The galvo ratings you should pay attention to are scan angle, the KPPS rating (kilo-points per second, higher is better), drift (less is better), settle time (shorter is better), linearity, etc. When purchasing galvo/galvo amplifiers it is best to purchase those that have differential differential inputs (3 pins usually, sometimes 4) to minimize noise.

The galvo you have shown appears to have differential inputs which is good. I am concerned that the galvos you have purchased are slow/upsold for what they are due to the presence of square mirrors. To support high speeds, it is best to reduce the amount of material that must rotated. For this reason higher speed and quality galvo sets usually have specially cut mirrors.

2. A single LaserShark is capable of controlling two galvo/galvo amplifiers (For X&Y control)

3. The LaserShark does not work with stepper motors. You do not need to program the galvo amplifier boards but you may need to tune the pid loop using the various pots on the galvo amplifier boards. I would not touch these until you need to.
Please see: http://macpod.net/electronics/lasershark/lasershark_usage_electrical.php

4. Some windows software is available. Prior to purchasing please review the following link and my github pages to verify it is what you expect: http://macpod.net/electronics/lasershark/lasershark_usage_windows.php

5. The source code on github for the firmware is the most up to date and is what is programmed on the boards.

6. The LaserShark will drive any galvo provided the input specifications of the galvo amplifiers match what the LaserShark will drive. This is mostly the same for galvo/galvo amplifier kits intended for laser lightshows (to accomidate the ILDA spec). LaserShark specifications are provided here:
http://macpod.net/electronics/lasershark/lasershark.php
and here:
http://macpod.net/electronics/lasershark/lasershark_usage_electrical.php

7. The XY2-100 protocol is a digital protocol. You shouldn't need a LaserShark to drive heads that use this protocol however some do seem to support analog input and these may be drivable by the LaserShark. I have found these heads are generally more expensive than just a standard galvo amplifier/galvo kit but would be happy to be proven wrong

38

3D Printers / Re: Multiple Galvos

« on: January 23, 2018, 10:15:58 PM »

To properly calculate the value you would need to sum up (plus multiply for amplifiers) the errors and non-linearity of all the components. I wouldn't want to make a guess without significant experimentation which I have not formally done. What I would do in your design is try to keep temperatures as stable as possible.

I think if i were experimenting with this I would try to use as focused a beam as possible and then increase the diameter if you find you have problems. I suspect as-is this won't be a problem due to the beam width of your laser (assuming you will keep it stock) and it's transverse electromagnetic (TEM) mode.

39

3D Printers / Re: Multiple Galvos

« on: January 22, 2018, 07:33:52 PM »

I haven't played with these scanner head types before. I see that it supports the XY2-100 digital program (which you wouldn't need/want a LaserShark to control). In quickly looking around the web I see that some of these heads support both analog and digital input. One of these might be controllable by the LaserShark. Do you have or can you request a datasheet and pinout from the manufacturer?

Yes, the F-theta lenses are a means to correct the projection plane that is frequently used by engravers/3d printers.

The area the laser is able to draw upon will depend on how far away the galvo system is from the drawing surface. As you move further away, the laser movements will become greater between points. The LaserShark has a resolution of 2^12 bits = 4096 theoretical points*. With a setup that allows for a 100mm printable area that means that each bit shift will move the laser focus by (100mm/4096) = 0.0244140625mm. For a 300mm area these points would be 0.0732421875mm apart

* Note that neither the DAC in the LaserShark nor the galvo amplifier pid loop is perfect thus you will likely not have a full 12-bits to work with outside of a theoretical sense. You will also need to take into consideration "drift" caused by temperature in the LaserShark dac, amplifiers, galvo amplifiers, and galvo feedback components.

40

3D Printers / Re: Multiple Galvos

« on: January 21, 2018, 11:24:21 PM »

Hi,

I split your topic to make this easier to track. Thank you for the sketch.

To gain higher resolutions and print size you could do something like this. Already the library contains a feature that will let you uniquely identify LaserShark units using their serial numbers. It may be a bit of a headache to align everything plus account for correction of the projection surface (remember you have to either use optics or software to correct for this!).

Have you considered putting a single galvo on an x-y table and move this to gain more resolution? It will be slower, but it should be simpler to build and likely cheaper too.

41

SX2/CN2 Tachometer Discussion / Re: Reverse switch for tapping

« on: January 15, 2018, 02:20:18 PM »

I don't think this idea is going to work. The mill is not particularly stable speed-wise at the low end which is not going to be kind to taps. I also don't believe the reverse is instantaneous.

The users who have wanted to install a reverse switch on their mill are using this in conjunction with a boring head run in reverse.

If you need to perform a significant amount of tapping operations you may want to consider purchasing a "self-reversing tapping head". The are large and cumbersome for the mill. Might be best to make the holes (or at least pilots on the mill) and then use a drill press to drill/tap the holes.

42

SX2/CN2 Tachometer Discussion / Re: Version 2 Arduino Code

« on: January 07, 2018, 03:07:36 PM »

Hi,

In blue the 7-segments are very easy to read. Two customers have informed me they use the 7-segments now vs the power light to identify if their mill is indeed turned off (their machines are in very bright areas). Having worked with OLEDs I would say that they would have similar visibility to the blue 7-segments (red/green are harder to see).

The version 2 of the tachometer does not use Arduino code and I do not provide the source

43

LaserShark Discussion / Re: RGB laser control TTL

« on: December 27, 2017, 11:03:51 PM »

Hi,

TTL lasers can only be turned ON (generally 5v) or OFF (0v) only. Analog lasers can be turned ON (generally 5V), OFF (0v) or partially on (anything between 5v and 0v). In this sense yes, you can use an analog laser controller (i.e. the LaserShark) to drive a TTL laser.

OpenLase has an option to only turn the lasers on/off too (In the Laser output configuration app, look under Color settings).

If you are asking if the LaserShark will be able to dimm your lasers (possible by turning the laser on/off at a frequency much higher than the galvanometer kpps rate to "fake" dimming), then no the LaserShark cannot do this. Generally if you look at the specs of TTL lasers (i.e those from ebay) they are only rated for 10khz which is much slower than the galvos thus making dimming impossible anyhow.

44

LaserShark Support / Re: TTL frequency

« on: July 31, 2017, 10:44:58 PM »

If it works with lasershark_jack and playilda it sounds like the laser is hooked up correctly.

with lasershark_stdin_circlemaker do you see the circle (just a very dim one?). Have you modified the program to change the laser brightness? What do the text lines output to lasershark_stdin look like?

45

LaserShark Support / Re: TTL frequency

« on: July 23, 2017, 09:13:06 PM »

The LaserShark has two analog outputs and one TTL output. The outputs are updated once every time a sample is updated (which corresponds to the PPS rating you have choosen).

I have not heard of a laser requiring a particular frequency. Usually what you see is the maximum ttl frequency that they can be operated with. What laser are you working with?