Converting a Boxford 250B

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20 Apr 2016 23:36 #73665 by andypugh
Replied by andypugh on topic Converting a Boxford 250B

I then jog the tool down to the bar close to the face and slowly up to it, checking with feeler gauges. Stop at 0.08mm distance.
Then select Z and enter tool offset (bottom choice in touch off menu) set to 0.08.
The DRO now shows 28.something. Is it not supposed to jump to 0.08?


Yes, it should. And it always does for me. Even if there is some confusion about what tool is loaded, any time you touch-off the position should show the new number. Unless your display is showing machine position. But if that was the case the T1 touch-off would not have worked either.

And it seems if I want to have the tooltable edit window I have to open it before doing much else or it will not open.
I'm still on 2.6/Ubuntu10.4 as my touchscreen does not work in 2.7/Debian.


That was a bug, and you can upgrade LinuxCNC to 2.7 without changining the OS, which should fix the bug and leave the touchscreen working. You just need to alter the repository name in the synaptic package manager.
linuxcnc.org/docs/2.7/html/getting-start...ha:updating-linuxcnc
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21 Apr 2016 20:58 - 22 Apr 2016 07:55 #73699 by Einar
Replied by Einar on topic Converting a Boxford 250B
I spent another evening fighting it. I may be onto something.
I have the tool edit window open. When I touch off in Axis I get a message in the tool edit window that it has changed. Of course, so I Reload the table. I got suspicious when it did not seem to change, so I opened the tool table in a text editor. And what happens is that it does not load the tool table, it stores it! It seems I should have used ReRead instead. So load means load the file from the editor?

I think I will refrain from using the tool table editor and just use the text editor and see if that helps.
Although I think the reason I opened the tool table editor in the first place was that I did not get what I expected from just doing it in Axis.
So maybe I did one formal mistake in the beginnning, and after that I was just doing/undoing for two evenings. I now know that is what the manual says, so there I have for reading the buttons and not the fine print. I just hope that was it.

Zzzzz... Next day today, and I'd just tell you yes, it was as I assumed. Don't know what the initial error was, but the bulk of wasted time is caused by what I did in the 2 programs were fighting each other.
.
Last edit: 22 Apr 2016 07:55 by Einar. Reason: Follow up

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24 Apr 2016 19:52 #73817 by Einar
Replied by Einar on topic Converting a Boxford 250B
I put 3 fingers in a wood planer today! Ouchh! Now done bleeding and got them packed in bandages it seems pushing buttons is an activity that hurts the least.
Good advice: Check that brain is engaged before pulling hands out of pockets!
One thing I started looking at is the velocity and acceleration figures. It seems to me that MAX_ACCELERATION and PID.P both influence acceleration. How do these interact?
Also what is interaction between MAX_VELOCITY / PID_MAX_VEL?
I set up a cheap indicator and zero Z at indicator zero. Then run G1 F<Test value> and G1 F1000 to check that top speed is not too high. Assuming the first may loose steps but the other not, so that the error one way will not cancel out on the return. Maybe it would be better to reverse those two, but the indicator is really very cheap.
What values would be most useful to watch in HalScope?
I notice that PID.I is zero. What would be a suggestion for it?

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24 Apr 2016 22:18 #73823 by andypugh
Replied by andypugh on topic Converting a Boxford 250B
You need enough P to follow the programmed accelleration. You will see that Pgain gives you faster acceleration on step-inputs, but LinuxCNC doesn't send step inputs.

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30 Apr 2016 19:13 - 30 Apr 2016 20:21 #74089 by Einar
Replied by Einar on topic Converting a Boxford 250B
Yes, it seems I can set P to pretty much what I want. If there is any difference it seems to be more P will give less following error and a more "noisy" following error (in the scope). I can be set to no more than .01 or that axis will sound like a metronome.
I think I will leave it as is now since it accelerates fine and does not seem to loose steps.

I swapped a tool today and now have the same griefs with the tool table. I tried everything I can think of. Even calling up the tooltable in a text editor and entering a number corrected by the offset from the DRO. Reloading the tool table in Axis after that does nothing! The Z DRO does not change, neither does the TLO Z DRO. If I then touch off Z again Axis will overwrite the tool table with the wrong value again. Changing focus to the editor I get a message it is changed outside it. I re-read it, and sure enough am back to (almost) exactly what it was. I don't really dare going to 2.7, and suppose this cannot be a common bug in 2.6.0~pre or it would have been known. I also tried to correct the tool table before starting LCNC but it did not do much good.

I can try again until it works, as that seemed do do it the last time. But I cannot spend a day every time I swap a tool! I need to figure out what this is.

ATM I don't trust it to run a part. The toolholders in there are not expensive, but I don't have replacements if they crash.
I need to find a place they sell round chocolate bars so I have something to run test cuts in. One thing it seems I can trust is the home switches. It seems there is no need to touch off X G54 each time I turn the machine back on.

I suspect my lack of understanding the G54 offset may be my problem. Let's assume I don't have a clue what it is. It is an offset, but from what? I think I need to wipe my notion of what it is and start again from scratch. Obviously not from machine zero, it is way too small for that.

What I did already is to use tool 1 as a "master tool", do a face cut and set G54 to 0. Then use that face to set tool Z to 0 after bringing each other tool to that face. That seems to set G54 to the offset from my previous tool setting session. And the tool settings will be off by the difference from my previous session to my current.
Last edit: 30 Apr 2016 20:21 by Einar.

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01 May 2016 09:11 #74100 by andypugh
Replied by andypugh on topic Converting a Boxford 250B

What I did already is to use tool 1 as a "master tool", do a face cut and set G54 to 0. Then use that face to set tool Z to 0 after bringing each other tool to that face. That seems to set G54 to the offset from my previous tool setting session. And the tool settings will be off by the difference from my previous session to my current.


This will work, and is what I do, but you also probably want to make sure that the master tool always has offesets of zero in the tool table.

On a lathe you may not need to ever edit the tool table directly, you can put all the values in with touch-off. It is easy to mess things up with versions before 2.7 because you have to remember to select "Tool Table" in the touch-off dialogue when setting any tool other than the master tool.

Also be aware that tool-offsets are not applied unless you issue a G43 command. You have to get used to typing M6T2G43 to change tools. (You can re-map the toolchange to work in a more lathe-like way if you want, but I haven't bothered as I am used to G43 now)

If you have offsets of zero in the master tool entry, then the other tool-table entries are offsets from the tip of the master tool.
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20 Jan 2017 17:07 #86263 by Einar
Replied by Einar on topic Converting a Boxford 250B
I still have not understood the tool table but my procedure seems to work, so I'll stick to it for now.

I'm trying to use Fusion360 CAM. Still not a success, I need to inspect/correct the post before commiting it, using the Tormach SlantPro postprocessor.

One I did not catch was that my spindle needs to run the opposite way of normal since the turret is behind and tools are mounted with cutting edges facing up. The cut was anything but nice and then the edge broke off the insert. Strange looking breakage though. It just chipped off the top. Then it dawned on me as I was about to try again. This time I looked at the chuck when spinning up and could see it was the wrong direction. I cannot see that at >3000RPM. A fix in the postprocessor fixed that. I'm afraid it will throw some errors in other operations though, but then I'll know the reason.

There are other problems too. It sends Z to # 5422 after each op. I just comment that one out in the postprocessor.

Lathe CAM in Fusion360 is still pretty basic, but for the price (free) it is the best ;-)
There is no way to design your own tools. My favourite: YNMG is not there. Neither are my threading tools, although I can use the ones there if I accept they will crash the holder in the simulation. My actual holder in the lathe is not. A good thing it's not the other way around.

Upgrade to the recent LCNC was tried, but my touch screen would not work. Maybe I should try an upgrade in the same Ubuntu version I have. But are there a way back if things does not work?

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22 Jan 2017 22:30 #86437 by andypugh
Replied by andypugh on topic Converting a Boxford 250B

One I did not catch was that my spindle needs to run the opposite way of normal since the turret is behind and tools are mounted with cutting edges facing up. The cut was anything but nice and then the edge broke off the insert. Strange looking breakage though. It just chipped off the top. Then it dawned on me as I was about to try again. This time I looked at the chuck when spinning up and could see it was the wrong direction. I cannot see that at >3000RPM. A fix in the postprocessor fixed that.


I don't know for sure that the PP is the place to fix it. Possibly M3 should always turn the spindle in the conventional cutting direction.

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