Denford 4th Axis can only rotate from 0 to 359.99 deg?

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JSKRABA
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Denford 4th Axis can only rotate from 0 to 359.99 deg?

Post by JSKRABA » Wed 08 Aug , 2012 10:35 am

Hi
Any one out there using the 4th axis for multi rotation work
Using the Compact 1000 with VRMilling 5 4th axis works OK but will not multi turn
Most software (Using Vectric mostly) assumes the 4th axis will multi turn ie. A720 is 2 revs but Denfords only goes to A359.99 so A390 will only go to A30!
I have used the Compact 1000 pro Mint file but that is the same APART from it solving another problem with A- values
With std Mint it ignores any A- values with Pro version its OK ie. G1 A180 (Forward 180 deg) G1 A-40 (Back 40 deg).

Anyone had this problem and has ideas?

Regards.

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Re: Denford 4th Axis can only rotate from 0 to 359.99 deg?

Post by Denford Admin » Mon 13 Aug , 2012 14:38 pm

I’ve looked into how the 4th axis works..
You can program any angular position 0 to 360 degrees (360 being the same as 0)
If you program say A370 it will mod the value with 360 and send it to 10 degrees.
If you program A-370 it will do the same and send it to 10 degrees in the opposite direction as it did previously
These coordinate are absolute, G91 does not effect the A value.

If you wanted to send the rotary axis around multiple times then I think the best way will be to use the G107 command.
This is in the V5 help file. It changes Y linear values into rotary values in order to wrap a 2D program around a cylinder.
Eg, if you programmed this:
G90
G21
G0A0
G107Y15.9155
G1Y200F1000
M30
The A axis would make 2 revolutions, because:
Setting the G107 wrap radius to 15.9155 gives an imaginary circumference of 100mm (2*PI*R)
So while G107 is active, programming Y100 will rotate the A axis 360 degrees....
Y150 will rotate 540 degrees total
Y200 will rotate 720 degrees total etc...

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Re: Denford 4th Axis can only rotate from 0 to 359.99 deg?

Post by Denford Admin » Mon 13 Aug , 2012 14:44 pm

As for the issue with A- values being ignored in Compact 1000 but not Pro machines - I've tested the Compact standard machine here and +ve and -ve values work OK.
It's be worth making sure you're on the latest version of VR Milling (5.52 at the moment)

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Re: Denford 4th Axis can only rotate from 0 to 359.99 deg?

Post by JSKRABA » Mon 13 Aug , 2012 21:37 pm

Hi
Thanks for reply on A- values
Its not that the software I have will not do this, its that if I load the standard Mint file for Compact 1000 and set 4th Axis available (does not work)
But when I select Compact 1000 pro mint file it works OK (But it keeps saying I have selected the wrong machine)
What is the differance in the Mint file?

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Re: Denford 4th Axis can only rotate from 0 to 359.99 deg?

Post by JSKRABA » Mon 13 Aug , 2012 22:24 pm

Hi
Thanks for your reply on the multi turn
It does do what you say ( I need to think about why it does this a little more)
BUT
If I do this the flat shape I need to produce is very complex
If I have a 50mm Dia (300mm long) billet and I want 4 start helix with Pitch if 50mm over length of blank
It should rotate 6 times for each cut.
Where do I start to work out the flat XY model to wrap and what should the G107 values be?

I am using Vcarvepro and that does the wrapping from input into a Macro. It does it for one rev and expand over the number of turns eg A2160 for 6 turns. (attached file)
Very simple G1 X295.000 A2610.000 Z-5.000 F2400.0 Move from X0 to X295 and A0 to A2610 deg (rotate 6 times) depth of -5 at feed 2400. (Y0 os over centre point of billet) then move A90 for start 2 etc.
I am assuming you are saying that there is no way I can use X,Y,Z and A past 359.99 deg?
Is this a limitation of VRMilling 5 or the Mint file or what?

Regards JCS
Attachments
wrap spiral test1.fnc
(1.22 KiB) Downloaded 697 times

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Re: Denford 4th Axis can only rotate from 0 to 359.99 deg?

Post by JSKRABA » Mon 13 Aug , 2012 22:58 pm

A- Problem
Problem gone with V5.52! Standard Compact 1000 OK with A+ & A-
Ta

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Re: Denford 4th Axis can only rotate from 0 to 359.99 deg?

Post by Denford Admin » Tue 14 Aug , 2012 9:13 am

I am assuming you are saying that there is no way I can use X,Y,Z and A past 359.99 deg?
Is this a limitation of VRMilling 5 or the Mint file or what?
Yes, I think that's just the way we decided it will work.
There are some limitations with the controller's axis position counters and allowing very large rotary postions may have caused issues.
For example, asking the A axis to turn 100 revolutions would be A+36,000 which would equate to 2.88 Million steps.

I think if you're trying to do something like the prog you attached then it would be easier to use G107 and program something like this:

G0A0
G107Y15.9155 (picked just to make the circumference 100mm for easier programming)
G0X5Z5Y0
G1Z-5F900
G1X295Y600 (1 turn is Y100 6 turns is Y600)
G0Z5
(next thread a 1/4 turn round
G0X5Y600 (going back to Y0 would unwrap the helical on the way back - which may be OK
G0Y625 (add a quarter turn
G1X295Y1225 (600+600+25
G0Z5
....

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Re: Denford 4th Axis can only rotate from 0 to 359.99 deg?

Post by JSKRABA » Tue 14 Aug , 2012 22:17 pm

Hi
Thank you for your explanation, which makes alot of sense.
To use your example any errors would be compounded with more revs and rev 90+ may be way out.
Now I know I will learn to live with this and understand it better.
Thank you for the start on the Multi turn using G107.

Regards JCS

PS I upgraded the spindle in the Compact 1000 to a 1.5hp water cooled spindle (China Version) with ER11 collet and linked the Inverter into the 0-10v conltrol voltage
It works great and I can now hear again! the most noise comes from the water cooling fans. I can still use the original motor if required.

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Re: Denford 4th Axis can only rotate from 0 to 359.99 deg?

Post by Denford Admin » Wed 15 Aug , 2012 8:56 am

Hope it works out for you :)

Have you a link to the China spindle by the way ? I guess it's far far quieter than the Porter Cable ?

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Re: Denford 4th Axis can only rotate from 0 to 359.99 deg?

Post by JSKRABA » Wed 15 Aug , 2012 20:49 pm

Hi
I got this one from eBay with inverter - http://www.ebay.co.uk/itm/250952849906? ... 1439.l2649

I had a pump and cooler unit so I got this one to avoid more noise and to allow the vacuum collection to work better.
I could have used their Air cooled version. Very accurate ER11 (came with 4 collets) upto 7mm
A simple adaptor ring allowed it to fit into the same mounting hole as the Porter Cable.
Inverter fits into the control cabinet (Above the mains cable input) and is powered on at the same time as machine.
Simple control connections from board 0-10V to inverter. I even managed to connect an overide Motor speed pot.
BUT the power to Spindle On/Off from board was tricky, although there is 24v to power the onboard motor relay there is not enough to power 2 so I just used the 240V out, to the old motor into a 24V PSU (loads around) which powered a relay switch connected to the inverter for Forward on/off to the spindle. It is very simple and quick to change it back to the original motor.
All works fine, much more accurate and it can cut soft metal.

Yes it is so quiet that a mark is needed on the spindle head to show it is rotating.

I attach a pic of the mounted spindle
Attachments
Dsc08391.jpg
Dsc08391.jpg (184.31 KiB) Viewed 12813 times

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Re: Denford 4th Axis can only rotate from 0 to 359.99 deg?

Post by Denford Admin » Thu 16 Aug , 2012 9:01 am

That's an amazing price for that setup! :shock:

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