Show Posts

6671

FAQs / Re: Migrating Machine - Parallel Port Will Not Run

« on: September 05, 2010, 06:06:55 AM »

As Hood has said many times - Check that your parallel port cable is OK and that it is connected pin1 to pin1 etc and not one of these PC to PC communication types with crossover connections.

Tweakie.

6672

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

« on: September 05, 2010, 05:46:59 AM »

You make it all look soooo easy Chris.

Tweakie.

6673

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: September 05, 2010, 05:06:35 AM »

Components added to the pcb. Fired it up and as luck would have it, worked first time.

This circuit takes advantage of the hysteresis in the switching characteristics of the 74HC14 inverter IC.
One gate is used to create a 5kHz square wave oscillator with the output charging a capacitor which is in turn discharged by a resistor the time constant of which creates the 1uS pulse through a second gate which is finally inverted through a third gate. Simple.

The upper trace shows the 5kHz oscillator output.
The lower trace shows the 1us pulses repeated every 200uS which is exactly the requirements for the Synrad 'tickle pulse'.

I am still undecided about the controller design but this circuit will at least allow me to test the laser to check that it does indeed work.

Tweakie.

6674

General Mach Discussion / Re: New people welcome !! Come in here and introduce your self!

« on: September 04, 2010, 01:19:50 AM »

cncbailey,

You need to post your question under the General Mach Discussion section to get a response to this question.
It may also help if you were more specific regarding the type of customization Screen, User input etc etc.

Tweakie.

6675

General Mach Discussion / Re: help in setting up needed for a noob

« on: September 03, 2010, 01:33:19 PM »

Ben,

If you have a continuity tester / meter you can identify the motor wires. Two wires are connected to one set of internal coils and two wires are connected to the other set of internal coils. Check for continuity then connect this pair to A+ / A- check for continuity and then connect the other pair to B+ / B-. It doesn't matter which way round the pair of wires go, as the direction of rotation is taken care of later in the Mach settings.

Tweakie.

6676

Show"N"Tell ( Your Machines) / Re: The Laser Project.

« on: September 03, 2010, 01:06:17 PM »

I have not yet decided just how I will be controlling the Synrad RF laser but whatever system I use i am going to need a 'tickle pulse' generator so at least this is one part I can start making already. The required circuit is extremely simple and I like simple.

The 'tickle pulse' generator has to supply a stream of 1uS pulses repeated every 200uS (5kHz) and this keeps the gas on the point of lasing and in readiness for the trigger or firing pulse which will in turn be a pwm stream ranging from 10% to 100% mark space ratio.

The finished controller will be modular in construction and this little pcb will just be incorporated into the main pcb (at least I think that's the way it's going to go).

This little pcb has been isolation routed, now to solder on a few components and test it out.

Tweakie.

6677

General Mach Discussion / Re: Milling marks????????

« on: September 03, 2010, 05:34:59 AM »

Just a thought, well a wild guess really, I had a problem which looked similar to this which was caused by tiny particles welding to the cutter tip and making unwanted gouge marks. This was with polycarbonate - the same problem did not occur with Plexiglass / acrylic.
Could you perhaps try a different material, with a higher melting point, and then see if the same problem occurs.

Tweakie.

6678