Messages

101

General Mach Discussion / Re: home and limits question

« on: May 23, 2007, 08:16:30 PM »

The soft stop is always the better one. But the software has to know where that is located to be able to slow down to a crawl.
The limit switch option controlled by the port and the pin ID is a mystery for the machine till it hits.
When I use the hard limit switch, then I even modify their X position during the run if I see that some obstruction is closer than I thought.
I don't think that both methods can really be compared. When you know you do not loose steps, and the code worked on is known, then I see little risk that the software would loose sync with the real world and require the hard limit switches. Soft would be fine. I just finished building my little pet, so I rely on the hard limits while adjusting and trying things. Once all looks cool, I use the soft limits for the apparent benefits.

Btw... I just connected an old USB joystick. Haha, very cool!
Lemo

102

Tangent Corner / Re: How fast can I go? Safely...

« on: May 23, 2007, 09:57:13 AM »

Excellent! Thanks you so much Graham.
I did a search on cutting MDF and ran into the chipload formulas.
Good stuff. Now I also understand why high rpm and slow feed are not good as they produce to much heat.
I set my spindle RPM down, ran a bit faster, and voila, it actually started chipping away and stopped pulverizing.
However, I would not have done that without the formulas and insight as the speed is rather scary now.
That little TAIG mill is flying through that stuff. I bought one of those contact free thermometers which look like a gun a couple of years ago and never really used that. Now I took it and measured the temp of the bit's shank during operation. Just for fun... I am not such a stickler usually. And.... it does show. Funny, I tended to do the wrong thing, as in high rpm low feed, as I thought it would make it easier on the cutter. Wrong. Now it's flying, cool, without squeaking which it did a bit before.
Just Great!
Thanks again!
Lemo

103

General Mach Discussion / Re: home and limits question

« on: May 23, 2007, 09:46:42 AM »

Think about it, the limit switch is not, compared to the home switch, at a fixed location.
At least not necessarily by definition.
The limit switch is simply signaling the event that a set limit has been hit. I move my limit switches when I have my 4th axis mounted, so the machine head stock does not collide, or better said, cannot collide. So the machine can know where home is and then certainly slow down while approaching it, but in the case of a limit, it has to stop dead and does not really know when to encounter that position.
In theory it would be nice to have the machine figure out where the limit is, equal to the home exploration. And then work as it does with the soft limits.
But in practice, the limits should NEVER be hit as per definition something is at fault.
And considering that, things are not going to improve from there.
I changed my workflow to tell the machine that I have home switches, then run it very close to the limit switches, note the locations, enter them as soft limits, then unleash heck on the workpiece. I have to do that as the limit switches are often triggered by the induced stepper noise on their lines. And I am to lazy to rewire right now. That method works very well, and I cannot destroy my little mill.
Cheers
Lemo

104

Tangent Corner / How fast can I go? Safely...

« on: May 22, 2007, 07:22:56 PM »

I am routing my first relief on my TAIG. Yessssssssssss!
I use a 3/32nd carbide ball end mill with a 1/4 tool diameter step over in MDF.
Works like a charm with 4IPM at up to a maximum 0.25 Inch cutting depth.
It seems... that I can go much faster. I started with 2IPM and now I tweaked it up to 4IPM.
Sounds good, no heat, simply carving away happily.
What would be the professional recommendations?

Is there a general table/rule of thumb/formula which can yield a recommended maximum speed for cutters and materials?
Or is this where the experience and the broken cutters start?
I plan to use aluminium at one stage.... but hesitate right now as I have no experience there.
One IPM might be to fast already... No idea.... so I stay away for now.

Thanks in advance for some insights
Lemo

105

General Mach Discussion / Re: Limit/Home switch X-axis problem...

« on: May 22, 2007, 06:33:19 PM »

I solved my problem. I used the hardware approach. I reversed one motor on the driver. Thus I could use the working X-axis setup in Mach3.
However, the next problem was that once all three steppers work, there is so much noise on the line that there were a lot of triggers of limits.
So I switched them off again and ordered an opto coupled breakout board... Sighhhh..... It never ends... doesn't it .
Lemo

106

General Mach Discussion / Re: Limit/Home switch X-axis problem...

« on: May 22, 2007, 07:57:08 AM »

No, no other switch. I did another test, pretty much the last thing which came to my mind. And that is to disable the limit X- -- or X- ++. THEN the homing works without the dreaded limit switch error.
BUT the limit switch function is dead (switched off), the homing with the switch clearing drive only happens on one side of the home drive. A negative home drive simply does not work right.
Is there a code module I can look at which is performing this task. I'm more than capable to help myself once I know where the faulty code is located.
Cheers
Lemo

107

Competitions / Re: ******Guess and win a G100 Grex******

« on: May 21, 2007, 07:04:06 PM »

Must be:
2,007,526
Lemo

108

General Mach Discussion / Limit/Home switch X-axis problem...

« on: May 21, 2007, 03:44:06 PM »

Great, I have all limit and home switches mounted on the machine. All works but the X-Axis....

When I let the machine home, it homes to the wrong side of the x axis. If I reverse the axis or home negative, the move to home seems to be alright, but then it simply drives into the end switch and instead of reporting home and auto-zero, it simply reports LIMIT SWITCH HIT and that's the end of that. How can I home to the right end switch and not to the left one?

Right now my tool 0,0,0 is above the right most corner towards the operator. It should be the left most corner so positive x movements go to the right.

Btw... I can inverse the Y-Axis and home and negative home. All good. All works. Just the X-Axis does not do the same. It only homes to one side and indicates a limit switch hit on the other side (negative homing).

Thanks for a hint, it's the only thing preventing me to run the machine. Sighhhh.
Lemo

109

General Mach Discussion / Re: Mach3 G100 Question

« on: May 21, 2007, 10:07:39 AM »

Thanks for the reply Brian. I thought so. But why should 3D be slower?
As far as I can read, the steppers (in theory and within the given physical limitations) would run smoother and possibly faster under the G100 control.
What would cause the 3D (I actually use 4axis) operations to be slower?
Cheers
Lemo

110

General Mach Discussion / Mach3 G100 Question

« on: May 20, 2007, 04:36:18 PM »

After a couple of weeks I have a handle on Mach3. PURE FUN!!!!!
But still, I have intermittent Parallel Port issues. Nothing major, just annoying.
So, to get rid of any machine load/parallel port dependecies.... would this work:

2.4 GHZ IBM Laptop communicating to
G100 Controller connected to xylotex driver.

Thanks for critique!
Lemo