Messages

7601

FAQs / Re: Step and Dir signals

« on: June 30, 2010, 01:44:47 AM »

Hi Zero Cool,

Welcome to the forum.

You are correct in what you say about the step and direction signals. Some controllers prefer active high for these signals but all the ones I have used (so far) prefer active low.

Tweakie.

7602

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

« on: June 29, 2010, 11:34:30 AM »

Hi Russ,

My plan for the temp controller was to keep it simple and hard wire the NC low output in series with my laser coolant flow sensor - if the temp rises above the preset then the switch goes open circuit and the eht unit shuts down power to the laser tube. It does only have one sensor input and I haven't yet figured out how to switch between two thermocouples, think I need inspiration here, any ideas ?.
The controller is made by IMO Precision Controls Ltd here in the UK and perhaps is not sold internationally.
You are certainly right about the C of G for my machine, bit worrying really, but I think it looks worse than it really is (fingers crossed).  

Tweakie.

7603

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

« on: June 29, 2010, 08:44:28 AM »

Hi Dan,

There are many different combination's of metals / alloys which exhibit potential differences which change with temperature variation, the most common being the Type K which is Nickel-Chrome / Nickel-Aluminum alloys. Fortunately, for me the different types are color coded so at least I know what type it is that I found in my stores. One thing is curious though the Ni-Cr is non-magnetic but the Ni-Al is magnetic .
This explains thermocouples better than I can. http://en.wikipedia.org/wiki/Thermocouple

Best regards,

Tweakie.

7604

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

« on: June 29, 2010, 05:26:09 AM »

Well I couldn’t find a thermocouple of the right design (I want to monitor the temperature of the cooling fluid as it leaves the laser tube with perhaps a second sensor to monitor the coolant entering the tube) so I decided to make my own. On the offchance anyone is interested in thermocouples I have attached a few pictures…..

1.   Piece of 6mm bore stainless tube and length of ‘Type K’ thermocouple wire.
2.   This is the tricky bit, the wires are spot welded onto the tube one on top of the other.
3.   With a simple mold I have used some car body filler to support the wires and give some protection to the weld.
4.   Completed tubular thermocouple which, with a bit of insulation, should indicate the flowing water temperature.
5.   Tested and it works.

Tweakie.

7605

General Mach Discussion / Re: Is anyone else using E1P1 / E1P0 to switch output #1 ?

« on: June 28, 2010, 12:36:17 PM »

Hi Ian,

fingers too fast for brain - why does that make any difference?

The faster an axis takes off from a standing start and the quicker it stops the less drawn out the unwanted increase in depth of cut at the start and finish of the kerf becomes. (on wood this is shown as a dot at each end of a line - quick acceleration, small dot - slow acceleration, bigger dot).

5000mm/sec^2 (velocity 15000mm/min)

You must have super low mass in your axis to achieve that Velocity and acceleration. My poor little steppers might just about manage a squeak. 

Tweakie.

7606

General Mach Discussion / Re: Is anyone else using E1P1 / E1P0 to switch output #1 ?

« on: June 28, 2010, 09:21:15 AM »

Hi Ian,

Thanks for the info, I must look into this a bit more then. I didn't actually measure anything, just looked at the results in a piece of scrap perspex.
Just out of curiosity and assuming you have a better memory than me, what acceleration figure were you using for your X -Y axis ?.

Tweakie.

7607

General Mach Discussion / Re: Is anyone else using E1P1 / E1P0 to switch output #1 ?

« on: June 28, 2010, 08:44:46 AM »

Hi Ian,

Thank you for the link, which I had not seen before. I have just given this a try (got quite excited) and although it may speed the Output # ? switching time there is still a delay before the next line of code is executed when using M3 or M1001.
With cutting acrylic this delay is unimportant to me it is just with engraving where the depth varies at the start and end of the kerf.
It is so annoying that the E1P1/E1P0 works so well... 'when it works'.   

Tweakie.

7608

General Mach Discussion / Re: Is anyone else using E1P1 / E1P0 to switch output #1 ?

« on: June 28, 2010, 06:27:28 AM »

Hi Hood,

Thanks for your response - Yes it is for no delay, or switching at the point of the axis movement, for a laser.

Funny enough the M10 /M11 combo also suffer similar, although slightly different, behavior. There is definitely something strange here as I have tried different computers with the same result.

I have attached a modified (m10/m11) version of the earlier GCode just in case anyone wants to see the difference.

Tweakie

7609

General Mach Discussion / Is anyone else using E1P1 / E1P0 to switch output #1 ?

« on: June 28, 2010, 02:58:07 AM »

I am having an issue with switching output #1 with the commands E1P1 and E1P0.

For most of a program it works just fine then suddenly gets confused (particularly with short moves) then returns to working just fine again.
Despite much experimentation I have not been able to get to the bottom of this or find the cure.

If anyone has experienced this problem and discovered the reason or found a cure I would be most grateful to learn the answer.

I have attached a simple GCode which exhibits this problem.

Thanks,

Tweakie.

7610

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

« on: June 27, 2010, 01:27:28 AM »

Think I have done it this time fellas. The temperature controller arrived yesterday, it's bigger than I had originally thought and gray paint or not, I can't find anywhere to fit it. 
I haven't found the right thermocouple yet so I may try my hand at making one (if I can find my spot welder which I don't think I have used in the last 10 years).

Tweakie.