(Non-)Tool-Change Coding

[jgrush]

Hi folks -

Very new to coding for CNC - In fact, I am taking a class right now and following along at home on my SB magnaturn 612 with MDSI OpenCNC control.

I am having a problem with tool changes (or maybe (non-tool-changes) and I am trying to figure out if I am just running up against a common issue or if this is specific to OpenCNC controls:

I start a program using tool #1, which is the tool in cutting position when I 'Sync' the lathe. It apparently does not take into account tool offset for tool #1 as there was no change to it before I started the part program. But since I am coding incremental moves, it cuts ok from my touch-off-determined starting position.

I tried programming a T0101 tool change but it gives me an error.

However, when I change to another tool, it loads the offset for that tool and suddenly it rapids away from the chuck and I find the tool point 3.5 inches away from the blank in the +Z direction. The offset of both tools is around 3.5 inches from the machine zero. I have a Part Zero set but it doesn't seem to take into account the tool offset.

It looks like I can solve part of my problem by moving the tool I want to use to another position or by changing to another tool position then back to T0101.

Is it normal that the offset for T01 is not loaded because there was no tool change? Is there a work-around that doesn't involve moving the tool turret?

Shouldn't the offsets be taken into account when I touch-off and set X and Z part zeros?

At least this tends to NOT crash the lathe... But I am still a bit confused.

Any Thoughts? Suggestions?, Merciless laughter?

Thanks for your consideration.

John
Santa Rosa, California

[txcncman]

Maybe I did not understand you problem. From your description, this is why it is wise to move the turret to a safe tool change position before commanding a tool change. I am surprised they did not teach you this in your class. It is what I teach my students. You may want to ask for a refund. Seems you are not getting your money's worth on training.

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[jgrush]

We learned to move to a safe position for tool changes.

When you Sync this lathe it wants tool #1 in cutting position for the Sync. Then it knows which tool is which. If I go ahead and cut with tool #1 it does NOT use its offset from the tool offset table. Is that normal?

Only if I change tools will it use an offset. I am trying to sort out if this is normal or if there is a strategy to make the offsets work if you use a tool without actually making a tool change.

An obvious workaround is to do a tool change before doing anything else.

[angelw]

We learned to move to a safe position for tool changes.

When you Sync this lathe it wants tool #1 in cutting position for the Sync. Then it knows which tool is which. If I go ahead and cut with tool #1 it does NOT use its offset from the tool offset table. Is that normal?

Only if I change tools will it use an offset. I am trying to sort out if this is normal or if there is a strategy to make the offsets work if you use a tool without actually making a tool change.

An obvious workaround is to do a tool change before doing anything else.

John,

It is quite normal for a control not to use a tool's offset unless its explicitly called. Many controls, depending on parameter settings, will cancel the tool offset when the Reset Button is pressed and therefore, require the offset to be called again prior to use.

Regards,

Bill

[dpuch]

I am not familiar with opencnc, but the way your describing your program start seems odd (needing to sync). Really take the time to make sure you know what offsets and coordinate systems are active and when they activate.

Regardless, if commanding T0101 with tool 1 as the current indexed tool gives an error, you should probably start there to find out why. There may be a parameter that fixes it so that would work.