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Topics - ggallant571

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General Discussion / 15 watt laser
« on: September 17, 2018, 08:31:03 AM »
I have purchased the components to build a 15W laser with linear slides. Two questions / concerns:

1. What do they mean by 50% duty cycle? Max PWM of 50% or run for 5 minutes and off for 5 minutes?
2. I am wondering if the HOME switch movement should be with no micro stepping to avoid the motor starting at a full step position.

Projects / World Map
« on: September 06, 2018, 05:45:31 PM »
I was away from home for a few days and came dome with LSAS - Laser Separation Anxiety Syndrome. Attached is a PNG map of the world along with an etching on scrap wood. I apologize in advance if I incorrectly adjusted the outline of your corner of the world. I was trying to get lines 3 pixels wide with 3 pixel separation. Feel free to make corrections and post better results.

Engraving / Stepper motor problem
« on: September 04, 2018, 04:46:42 PM »
I am having a strange stepper motor problem. The etcher has a single motor on the X axis and 2 motors on the Y. X is working fine, Either of the Y's by themselves is OK. Both Y's and they seem to be fighting each other. Lots of jitter and noise. Almost as if one motor was being driven as a generator. Swapped cables and driver boards. This fixture had been working very smoothly. I think all three motors are identical.

General Discussion / Adjustable wheel mechanism
« on: August 25, 2018, 05:14:52 PM »
Some time ago there was a discussion and a post about a mechanism to adjust the tension on the carriage wheels. When I run the X axis at high speeds (5000mm/min) there is a significant overshoot. Most evident when cutting a square. The trace corrects within 2mm so I am convinced it is mechanical. The wheels feel tight but the etch tells a different story.

Projects / Almost useless etching
« on: August 25, 2018, 08:20:04 AM »
We have had two grandsons for most of the summer. Neighborhood game was Pokemon. The younger designed and built an elastic band powered catapult. For a finishing touch we etched the attached image in the wooden frame. For the uneducated, it is Golem who has some value that I do not comprehend but was easy to outline. Also etches nicely on a 100x100mm slate.

General Discussion / G-CODE Error:25
« on: May 24, 2018, 05:15:46 PM »
I have been getting occasional error:25 messages with grbl 1.1f. This is on a core-xy etcher. The effect is usually an unwanted horizontal line.

Projects / Thermal measurement fixture
« on: May 13, 2018, 12:49:00 PM »
As a result of a discussion in another thread I have started work on a fixture to try an measure the energy disapated by a diode laser. The basic idea is to build a semi enclosed chamber that contains a temperature sensor. Fill the chamber with a known amount of water and shine the laser beam into the chamber. Hopefully it will result in a change in temperature with no damage to the chamber.

First prototype is on the printer. It consists of two parts, base and a lid. The inside diameter is 50mm and the height is 30mm. The lid has two holes. One for the laser beam and a second for a DS18B20 stainless steel temperature probe. The lid is finished and looks good. The base has 3 hours to go!!
Plan is to use an Arduino Nano and a small OLED or TFT display for posting results.

General Discussion / laser cutting chocolate
« on: May 06, 2018, 08:31:32 AM »

General Discussion / Image prep question
« on: March 29, 2018, 07:16:33 PM »
I want to do 9 etchings for a friend in slate. Unfortunately for me he is a talented artist with skills well beyond mine. The panels contain simple subjects with partial black outlines. The subjects proper are drawn with a pastel paint that quite artistically does not match the outline.

Could be etched in wood with varying intensity but need the black/white for slate. It took more than a full day for me to do the first image and I was not pleased with the result. I think they will look best with a simple complete outline.

Looking for ideas on how to reliably extract an etchable image with a uniform fixed width outline. Is there a tool to import a sloppy outline and output a clean one?

General Discussion / Etching Granite
« on: February 06, 2018, 08:39:48 PM »
I was at a kitchen counter shop this afternoon and got a couple pieces of scrap kitchen countertop granite. The black (with white speckles) is etchable with a 2.5W laser. Not great and the shine from the stone makes the camera picture useless. Etched their business name on both sides at both 240 and 60 mm/min. The rougher surface (forget the trade name) is less visible than the polished one.

Also got a light (almost white) chunk that I expect will remain unscratched.

Open to suggestions regarding taking pictures of faint images on a shiny background.

BTW - They have a few tons of scrap granite along with a large quantity of scrap birch plywood good for small images or testing.

General Discussion / Wine Glass Etching
« on: January 31, 2018, 01:29:06 PM »
I have enter the wine glass etching game. Built a fixture based on a small rotary table, two 8mm rails with linear bearings, and a 1.6W laser module. Glass is held in a vertical position in a 3D printed spring loaded clamp. This eliminates the need to support the far end of the glass.  Currently Y is vertical and X is rotational. Electro/mechanical components working smoothly. Starting on the etching. Questions:

1. Prefered ink/paint.
2. Laser intensity.
3. Burn speed.
4. DPI.
5. How to position/aim the laser.
6. Is it "better" to etch horizontal or vertical.

General Discussion / NEMES Show
« on: January 27, 2018, 08:05:44 PM »
For anyone in the New England USA region the New England Model Engineering Society, NEMES, is holding its annual show on February 17, 2018 at the Charles River Museum of Industry in Waltham Massachusetts. I plan on bringing  a 2.5W core-xy flat bed  etched and a 1.6W wine glass etcher. The core-xy has been behaving nicely for some months now while the rotary glass machine is still under construction.

I have small wooden discs (25mm) onto which the visitor can engrave their initials. Also have some NEMES specific images engraved in glass, wood , & slate which will be donated as door prizes for the exhibitors.

General Discussion / Slate problem
« on: January 13, 2018, 02:14:29 PM »
I just tried to etch a slate coaster with 2.5W laser and the result was very faint. Not sure that my speeds are accurate but used 900 mm/min at full power. Running a second  pass to see if it improves. The image has lots of lines that are 3 pixels wide in all directions. Etched ok on test cardboard and the final product will be on a mirror. Any thoughts?

General Discussion / Lead screw design problem
« on: January 02, 2018, 10:58:12 PM »
I have built a 500x500mm etcher using 8mm lead screws. As I have a similar machine using belts with a core-xy scheme this design was intended to highlight the build complexity and performance of the two drive mechanisms. After a day of testing and tweaking the software & firmware I have a couple of problems to solve:

1. The lead screw design appears to have a max speed of approx 2700 mm/min. Beyond that the motor just chatters.
2. The Y motion is very loud. X is smooth and quiet.
3. The Y step action is very sharp. Very noticable when etching and doing a line reversal.

Distance and speed measurements appear to be very accurate. Cut a 250mm square out of paper and measured the sides and diagonals.

The steps per mm is set at 400 due to the lead screw thread and the 16X to the stepper motor driver. Wondering about:

1. Changing the 16X to 4X (or 1X).
2. Wiring the Y motors on separate driver chips.
3. Adjusting the current limit.

General Discussion / Line widths
« on: December 22, 2017, 05:04:54 PM »
I have 8 images that started as clip art. Plan to select 6 and etch a 3D puzzle for my granddaughter. Put 4 of the 50x50x50mm blocks together into a square and etch the 100x100 image across the 4 faces. Then scramble the blocks and put another image on the new faces. A couple of problems/questions arouse.

First - Being the least artistic person in the universe I have no idea if the finished project should have the wood grains aligned or random. Two of the faces will be end grain.

Second - When I test printed the images I noticed that the outline paths are different widths. I recall using a free online service that converted rastor to vector with user specified line widths. That memory cell got zapped.

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