[extanker59]

Does anyone know of a workaround for the maximum # of revolutions the rotary can make? I've contacted Haas and I'm told it has a maximum revolutions of 99,999 degrees. Our VM-2 and VF-2ss will actually do 154,000 degrees but on our longer weird shaped parts we get a better finish with a full 4th axis toolpath from tip to end. So I have to change my stepover to get under 154,000 degrees. What do you guys do?

[KenFoulks]

If you can rotate 154000 degrees from 0, you should be able to index to -154000 degrees and then feed along 308000 degrees continuously.

[keebler303]

Or maybe you could do half, ramp out, rezero the rotary and keep on going?

Matt

[extanker59]

Thanks guys.
Ken, I'll try to see if I can get our CAM reseller to adjust our post to let me start at a specific angle. It's been 6 months but I believe I've asked that and they said no but I'll ask again.
Matt, I've tried that and it leaves a mark where they stop/start. And, related to the above start angle, it unwinds a heck of a long time. Maybe an adjusted post again. Can polish the mark out sometimes but it's a pain. Other times we don't want marks in the part.

[extanker59]

Ken, I jumped the gun. We would have to unwind the rotary 154000 degrees before even starting the cut. That takes a long time. Is there a way to tell the machine that it's already there? Similar to a rapid zero return (G91 G28 A0)?

[KenFoulks]

Sorry, there is no way to do a quick rotary type move, you can get a faster rotary. For example:

HRT-210 = 100 deg/sec
HRT-210HS = 130 deg/sec
HRT-210SHS = 360 deg/sec

You should be able to set your G54 to A-154000. This should allow you to unwind first, without editing your post.

[extanker59]

OK, thanks. I've added the A moves in the past.
Can you give us some insight as to why the rotary even has a maximum? This question always comes up when we run into this issue.

[keebler303]

I'd guess the control has a limit on the counter that keeps track of where the axis is. It might be 32 bits or 64 bits or something else I don't know. On any normal linear axis, you will run out of travel before you come close to the limit. On the rotary, you can spin forever so it can become an issue. I am surprised that this issue hasn't been dealt with, it is possible to handle a rollover of the counter so you can keep going.

I'd think that your use of the rotary is quite common practice; Haas should come up with a solution to have a (virtually) unlimited angular position on the rotary and you should also be able to tell the axis it is at any arbitrary position. Since it repeats every revolution it's quite a waste to unwind 400 revolutions just to be at the exact spot you were in 10 minutes earlier with a different number in the DRO.

Matt

[extanker59]

I agree, Matt.
And I appreciate the help I've gotten from this forum and Haas. I'm just trying to work with what is and not what might be.
It is a head scratcher though.
Is this a common issue across brands? I assume so.

[keebler303]

If you're running multiple parts, you could unwind, run from -154000 to +154000 and then have a second one run from +154000 back to -154000 so you didn't have to unwind every time. This might take some care with the gcode but I'd think it could be done.

Matt

[extanker59]

Good idea. Then I'd just have to run it to the extreme angle once per run. Unfortunately, we're doing prototypes and quantities are so low it might not be worth the effort. But I'll keep that idea in mind for the future.
Thanks

[Anders6612]

I think there should be a way for reset rotary tables,
G91 G28 A0 But perhaps some parameters should be changed
for that to work first.

We used a setting that reset rotary after every turn, (Max 359.999 deg)
and the Post is set to count for that.

[extanker59]

We can reset the rotary back to zero using G91 G28 A0. That's not the issue.

On the second part or your answer: We are using a continuous spiral toolpath, rotating about the A axis, and traveling in the X direction. On a part that is 6" long with a step over of .003 that's 2000 revolutions which means 720,000 degrees. This toolpath makes for a great finish on things like hand grips for surgical instruments.
It's not positioning which is what I believe your answer is suggesting?

[Anders6612]

I dont mean positioning, our cam post out code to 359.999 deg,
when it starts with zero again. But the rotary takes the nearest way and continues.

Example:

A0
A50
A100
A150
A200 *
A0

* As soon as it is over 180 deg, the rotary takes the nearest way to zero.
It continues the same rotation.

Our rotary is set to reset after 359.999 degrees without doing anything,
and no limit for amount of revolution.

I dont know if it is possible to set parameters on your machine for that,
but on the WFL at my old work it is set as standard.

[Machineit]

You know, I bet some super software guy out there could write a program with Haas that would just turn the unit on at a certain speed by controlling current and disregard positioning.

Also, you could use the 4th without doing a normal connection to the machine. Use a M code to turn on a DC power supply at the correct current and just have the rotary turn without monitoring position. No need to rewind either.

Come on, I know you guys can do this!

Mike

P.S.: I've run my rotary motor off of a battery charger during testing!

[KenFoulks]

What is your ideal range for this setup?

[keebler303]

I dont mean positioning, our cam post out code to 359.999 deg,
when it starts with zero again. But the rotary takes the nearest way and continues.
.

Anders, I think this would solve the issue entirely. If the axis position reset every revolution, you would never exceed any limit. Your post would have to be changed output something like:

A0
A90
A180
A270
A0
A90
etc.

Rather than the current:

A0
A90
A180
A270
A360
A450
etc.

You know, I bet some super software guy out there could write a program with Haas that would just turn the unit on at a certain speed by controlling current and disregard positioning.

Also, you could use the 4th without doing a normal connection to the machine. Use a M code to turn on a DC power supply at the correct current and just have the rotary turn without monitoring position. No need to rewind either.

Come on, I know you guys can do this!

Mike

P.S.: I've run my rotary motor off of a battery charger during testing!

Assuming you have a brushed rotary, you could do this. There is no way you could keep true position like this. If it is a contour, your Z movements need to be synced with the A position.

What is your ideal range for this setup?

Ken

I would think the ideal range would be the full usable X axis travel with the rotary installed at maybe .001" per revolution stepover. That's 20,000 revs easy.


Matt

[extanker59]

Ken, ideal range would be unlimited but maybe 999,999 degrees assuming it has to have some kind of limitation? That range would put it in my usual size but some would be out. Put me at around 8.3" long at .003 step over. Normally we are around 6" but it varies.

Matt, I'll check with the post guys to see if it can be set up like that but it sounds dicy. What if you went to 359 degrees then wanted to reverse to 10 degrees? Not all my toolpaths are continuous spirals.

[Machineit]

Assuming you have a brushed rotary, you could do this. There is no way you could keep true position like this. If it is a contour, your Z movements need to be synced with the A position.

If they are doing it in a continuous spiral they are most likely coordinating Z and X and not A with Z so this would work.

[keebler303]

If they are doing it in a continuous spiral they are most likely coordinating Z and X and not A with Z so this would work.

This would only work for a cone, correct? What if you were doing something like the lobes for a roots type blower?

Matt