Messages

6831

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

« on: May 03, 2011, 11:38:30 AM »

No problem using this thread - this forum is all about sharing knowledge (it is slightly Mach related so I think we can get away with it  )

As far as I can see, there are two issues regarding setting up.

1) Matching, where the power output of each board is the same and adjusted with R3 (see earlier posting).
2) Tuning, where the RF frequency of each board is the same and adjusted with C5.

An oscilloscope, preferably dual trace, would be ideal when adjusting the frequency to match both boards. I don't think Synrad specify the exact frequency although it is probably around 30Mhz so you will have to measure the good board and adjust the repaired board to match it.
Take care when making any adjustments (use non ferrous, insulated tools) as high power RF is dangerous stuff to mess with.

Tweakie.

6832

General Mach Discussion / Re: problem with the X ais

« on: May 03, 2011, 11:05:20 AM »

Hi Ennech,

Choose a value for microsteps that your machine runs smoothly with then, within motor tuning, set the steps per unit accordingly and adjust the velocity and acceleration to suit. Once this has been done there is no need to adjust microsteps again unless you think that you can improve machine performance over your earlier setting up.
Check all your wiring for poor connection, especially the axis you are having trouble with and also check the mechanicals such as loose coupler between stepper and leadscrew (check all grubscrews for tightness) etc. etc.
I know you have probably already done all this but most problems turn out to be something real simple that has just been overlooked.

Hope this helps,

Tweakie.

6833

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

« on: May 03, 2011, 10:44:38 AM »

Do you have a problem with both RF boards ?

I am no expert here but I understand that it is quite common for one RF board to fail and the laser to continue to operate on reduced power. So far I have seen two Type 48's which have had just one RF board replaced at some time or another during their lifetime.
The MRF151 is a slightly higher gain than the MRF150 but they are essentially the same component. The mica caps will be the same value on both boards.
I am uncertain about the setting up / matching but if it is adjusted at the threshold then lasing will begin at a pulse width of 3uS +/- 0.5uS at 5kHz PRF.

Tweakie.

6834

General Mach Discussion / Re: halfmoon instead of circle

« on: May 03, 2011, 08:31:47 AM »

You have to be cunning when it comes to avoiding electrical noise problems and probably the single most common source comes from wiring loops. Loops act as antennas and pick up anything, especially if it is not required (Murphy's Law).
Avoid Earth Loops and avoid GND Loops.
Treat Earth and GND as two separate circuits.
Only terminate the shield of cables at the controller end and preferably to one single point.
The list goes on....

Tweakie.

6835

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

« on: May 03, 2011, 08:03:21 AM »

The same here, regulated 30 Volt, 14 Amp (made in China).

Tweakie.

(Observe caution with the riser from the tube, this is in a gas seal and has to be treated with respect when un-soldering / re-soldering the cap. Also all the conductive carbon / metal deposit (from the arcing) has to be removed from all the insulated areas of the circuit board if repairing).

6836

General Mach Discussion / Re: halfmoon instead of circle

« on: May 03, 2011, 07:51:42 AM »

Where would I be getting the noise from?  The plasma's breaker is still shut off.

Electrical noise is everywhere, PC, strip lights, fan, even from your neighbours on your incoming mains supply. 

Seriously though, good routing of wires and shielded cables really pays off in the long run.

Tweakie.

6837

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

« on: May 03, 2011, 07:30:53 AM »

Ohh dear. 

With a bit of luck it is just the 1000pF silver mica which has expired.

Here is the RF board schematic (assuming you have the version with just one single RF output transistor).

Tweakie.

6838

General Mach Discussion / Re: Mach3 loses Y axis location during code

« on: May 03, 2011, 06:20:54 AM »

Well, that's that then as the forum limit is 6MB.

(I regularly run code in excess of 340,000 lines which zip to less than 4MB).

Tweakie.

6839

General Mach Discussion / Re: Mach3 loses Y axis location during code

« on: May 03, 2011, 01:57:20 AM »

Chad,

May be an idea if you post your GCode, this way it can be established if it is the fault of the code or your setup.

Tweakie.

6840

Show"N"Tell ( What you have made with your CNC machine.) / Re: MODEL 629 S&W MAGNUM

« on: May 03, 2011, 01:50:05 AM »

Rich,

Looking at the grain structure of that magnum - is it usual for S & W to use a casting for the chamber ?

Tweakie.