Messages

8351

Show"N"Tell ( What you have made with your CNC machine.) / Re: My first attempts at laser engraving.

« on: May 09, 2009, 09:17:25 AM »

Why wait until you are big ?.

Tweakie

8352

General Mach Discussion / Re: need help step per unit

« on: May 08, 2009, 12:01:20 PM »

Hi elgammmmal,

Are you working in mm or inches here.

Tweakie.

8353

Show"N"Tell ( What you have made with your CNC machine.) / Re: Isolation Routing for PCB's.

« on: May 08, 2009, 11:33:22 AM »

Another small circuit board - this time it is a simple, two position driver for a bipolar stepper motor.

Tweakie.

8354

Show"N"Tell ( What you have made with your CNC machine.) / Re: Gertrude Gets Some!

« on: May 08, 2009, 11:26:24 AM »

Brilliant work there Chris - I agree, you certainly are sharp. 

Tweakie.

8355

Show"N"Tell ( What you have made with your CNC machine.) / Re: My first attempts at laser engraving.

« on: May 08, 2009, 05:01:35 AM »

Thanx for the link - much appreciated.

Tweakie.

8356

Show"N"Tell ( What you have made with your CNC machine.) / Re: My first attempts at laser engraving.

« on: May 07, 2009, 03:11:35 AM »

Hi Dave,

At the moment I don't have a video camera (spent all my allowance on a Sony SLR and Minolta 70-210 'beercan') but just for you I will try to obtain a cheap webcam that will work with my laptop. Actually you are not missing much, with a feedrate of 20mm per minute It would probably be like watching paint dry. What would be far more interesting is a video of me photographing the laser in action as I tape one lens of the protective goggles to the camera lens filter (to give some degree of protection to my expensive image sensor) then shut one eye and look through the remaining goggle lens to take the shot. Glad no one can see me really 
It perhaps should be noted here that viewing a laser through any optical device is a bad idea for your eyesight.

Incidentally these solid state lasers cannot be turned on quickly as they require a 'soft start' in order to meet their expected life span. Therefore, in use, switching them on and off quickly requires a shutter system and I am currently working on this to solve the problem of unwanted burns when the axis is accelerating / decelerating from the start or finish of a line. First attempt at a rotary shutter was not too successful so I either have to improve on it or start again with a sliding shutter idea. I will add to this post when I have more information.

Tweakie.

8357

Show"N"Tell ( What you have made with your CNC machine.) / Re: My first attempts at laser engraving.

« on: May 05, 2009, 10:31:37 AM »

Thanks RC,

I was thinking of using the Z axis direction signal but this looks like a better way - I must try it and see how it works.

Tweakie.

8358

Show"N"Tell ( What you have made with your CNC machine.) / Re: My first attempts at laser engraving.

« on: May 05, 2009, 10:07:18 AM »

Hi Hood,

I bought the laser last year and Virtual Village stocks probably change but I am sure it will be back again. (hope so because I want another one).

This Road Runner is approx. 65mm across and laser engraved into aluminium clad plastic engraving laminate. The gloss finish stuff did not work but this matt or brushed surface is just fine. Although the line width is not quite as fine as can be achieved with an engraving point it is not far off. The laser was positioned approx. 60mm off the work and focused to the smallest spot I could get on the surface. There are a couple of dings, top right, which were the focus point and the starting and finishing point. There is also a slight line from the end of the engraving to the home position at the end of the job. I will have to connect a laser enable / disable from the LPT port and perhaps link it to the Z axis function. Does anyone have any ideas about this please ?.


Tweakie.

8359

Show"N"Tell ( What you have made with your CNC machine.) / Re: My first attempts at laser engraving.

« on: May 04, 2009, 12:00:03 PM »

Hi Dave,

I am only too pleased to share any info I have. All I know about CNC has come from you guys sharing your info.

Another piece of information - When the laser is operated at 2 Volts it produces a faint beam which is ideal for focusing because there is no loom and the beam can be adjusted to the smallest spot then it only lases when the voltage is increased to 5 Volts - pretty similar to the operation of the laser cross hair pointers we use for the tool positioning.

Couple more pics. - The Mach write wizard allows GCode to be created without Z moves which is ideal for experiments - This little laser cuts through 4mm high density foam (the stuff I use to protect RC servos and receivers) too easily, in fact it scored the surface during the fast G00 moves. It also makes short work of pvc electrical tape too.

Tweakie.

8360

Show"N"Tell ( What you have made with your CNC machine.) / Re: My first attempts at laser engraving.

« on: May 04, 2009, 07:21:50 AM »

Hey Guys,

I am still learning about this process and don't know all (hardly any really) of the answers myself yet.

The laser I have used was bought last year from Virtual Village, one of the Chinese retailers, and came with its own constant current power source (picture attached) which just requires a standard 5 Volts regulated supply. It cost around £35 (GBP) plus the shipping cost.

The laser is used in CW mode (continious operation) and my GCode file was edited to delete all the +Z moves completely and replace the -Z moves with G4 P3 to give a dwell before moving off from each new starting position. When the G0 moves are made they are too fast for the laser to bite therefore focus was set once, at the start of the job and without any subsequent Z moves using a feedrate of F20 (mm/min) and G0 inbetween the results were as you can see in the initial photos. Increasing the feedrate thins the line width and reducing the feedrate thickens it. (I guess the whole process must be very similar to plasma cutting requiring pretty much the same disciplines).
I did modify the laser to add a focus ring (the clear acrylic part on the front) but all this does is allow me easy focusing adjustment without using any special tools.

This laser does focus well even though it has plastic optics (min. 30mm - max. the length of my workshop) and was originally purchased as an allignment tool for a larger YAG laser which I have been slowly constructing for the last 6 Months or so (not sure if I will ever get it finished though). It was just by chance that I fitted it to my CNC to see how it would cut vinyl. Now it is a whole new ball game and I have so much learning to do (all the laser engraving machines I have seen so far use fast raster scan and pulsed laser operation) CW operation and vector drawing is just like conventional engraving and well suited to relatively slow moving CNC machines such as mine.

Thanks Guys for the interest - I will post more info and pics as things develop.

Tweakie.