Messages

7541

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

« on: May 24, 2009, 06:35:45 AM »

Well Chris the results were not successful. I cut your pendant, before my wife had even noticed that the candles were missing from the lounge, it is nowhere near to your high quality of work but OK for my testing. I have concluded that with a point laser beam the heat generated is too localised to cause the type of surface reflow of the wax that is required. This does not mean that it is not possible but I think that the beam would have to be modified to more of a fan shape and of course that would require considerable power from a laser and well beyond my 150 mW.
My point beam is smaller than 0.1mm so in the test I used a step over of 0.1mm and the surface finish of the wax was not improved at all – in fact it was a lot worse. The microscope photos show the surface finish after machining and after laser treatment. It was a long shot but who knows it might have worked !.   

Tweakie.

7542

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

« on: May 22, 2009, 12:57:40 PM »

No you don't  - you just love it !

Tweakie.

7543

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

« on: May 21, 2009, 07:28:52 AM »

As far as I can see the Z dwell is no problem as this can avoided by the Z inhibit function within Mach. The major problem here is that your existing toolpath makes multiple X passes between each Y move and you would probably end up producing laser marks to replace the tool marks. 

Tweakie.

7544

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

« on: May 21, 2009, 03:20:52 AM »

OK Chris, I see the application - brilliant idea. If you use modulation to control the laser (0 to 15kHz say) you will be able to have full command over the amount of radiated power from the laser for any feed rate that you choose. I have not seen modulation units for sale but it would be relatively easy to construct, I think, using a 555 timer or the like to create a variable PRF of a fixed width pulse. I will give this more thought and report back.

Tweakie.

7545

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

« on: May 20, 2009, 07:08:18 AM »

You have just gotta get more sleep buddy.

Tweakie.

7546

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

« on: May 19, 2009, 12:38:50 PM »

Thanks Chris - I can tell that it is 2 am. 

Tweakie.

7547

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

« on: May 19, 2009, 07:50:12 AM »

Chris,

How and where do you now attach the sprue to pour the casting now that the hub has been removed ?.

Tweakie

 

7548

FAQs / Re: Laptop requirements with Mach 3

« on: May 19, 2009, 07:47:13 AM »

This is certainly a good forum with so many people sharing their ideas and solutions to problems.

Tweakie.

7549

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

« on: May 19, 2009, 07:38:27 AM »

Chris - In the process of experimentation I have concluded that a shutter system (to turn the laser on and off) is preferable to using the modulation input (at TTL levels). This enables the laser diode to be operated by a completely isolated constant current source and eliminates any possibility of voltage spikes from the machine or computer causing any damage to the diode. I have detailed what I have done so far on my website and the link is below. I will include the shutter details when I have time. Good luck and I look forward to seeing your results.

                                          http://www.cooperman.talktalk.net/index_files/Page4549.htm

Tweakie.

btw. thanx for the links Martin.

7550

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

« on: May 17, 2009, 02:36:19 AM »

Right - now it all makes sense. 

Tweakie.