CNC conversion Questions and Linuxcnc
- Kermitfrog
- Offline
- New Member
-
Less
More
- Posts: 7
- Thank you received: 0
19 Aug 2017 04:04 #97730
by Kermitfrog
CNC conversion Questions and Linuxcnc was created by Kermitfrog
I'm planning conversions for a g0602 lathe and a PM727 mill both using Linuxcnc. Looking at boards from cnc4pc. Arturo says the c3 boards are only good for 20k, so will be ok for the lathe under 2000rpm, but probably not for the mill. How many pulses per revolution does one need from encoders for linuxcnc? how does linuxcnc deal with different gear or pully ratios on spindle drive? I understand that encoder feedback is necessary for lathe to do threading and constant surface speed, but is there any advantage to spindle encoder feedback on a mill? Planning on Leeson metric 3ph motors for both conversions, 1800rpm motor on lathe and 3400rpm motor on mill. Some say rs484 best for comm between vfd, any thoughts on this? Would Mesa boards be better choice? And if so why and in what ways?...or is it just a matter of personal preference and price?
Please Log in or Create an account to join the conversation.
- Kermitfrog
- Offline
- New Member
-
Less
More
- Posts: 7
- Thank you received: 0
20 Aug 2017 01:19 #97754
by Kermitfrog
Replied by Kermitfrog on topic CNC conversion Questions and Linuxcnc
Did I post these questions in the wrong category? If so I apologize...and please advise if there's a more appropriate category to post. Looked through a lot of previous posts for answers but not much luck. Was hoping others with more experience could give me some direction
Please Log in or Create an account to join the conversation.
- Todd Zuercher
-
- Away
- Platinum Member
-
Less
More
- Posts: 4978
- Thank you received: 1377
20 Aug 2017 02:10 #97755
by Todd Zuercher
Replied by Todd Zuercher on topic CNC conversion Questions and Linuxcnc
The main advantage I can think of for having encoder feedback on a mill would be doing rigid tapping or gear hobbing. I'm not sure what else you might need it for.
Rs485 is a way to add a lot of spindle control features without doing a lot of wiring. The down side is I may not have the greatest real time performance.
Mesa cards are great hardware and usually well worth the added expence.
Rs485 is a way to add a lot of spindle control features without doing a lot of wiring. The down side is I may not have the greatest real time performance.
Mesa cards are great hardware and usually well worth the added expence.
The following user(s) said Thank You: Kermitfrog
Please Log in or Create an account to join the conversation.
20 Aug 2017 02:54 #97756
by rodw
X 2, I've just tuned my Z axis using a 7i76e and I'm getting about 90k steps per second and the little Nema 23 is fairly screaming.
Replied by rodw on topic CNC conversion Questions and Linuxcnc
Mesa cards are great hardware and usually well worth the added expence.
X 2, I've just tuned my Z axis using a 7i76e and I'm getting about 90k steps per second and the little Nema 23 is fairly screaming.
The following user(s) said Thank You: Kermitfrog
Please Log in or Create an account to join the conversation.
- Kermitfrog
- Offline
- New Member
-
Less
More
- Posts: 7
- Thank you received: 0
20 Aug 2017 05:39 #97759
by Kermitfrog
Replied by Kermitfrog on topic CNC conversion Questions and Linuxcnc
Thanks for the replies. Looking at the Mesa 7i76 and 7i76e, the max encoder input is 10m compared to only 20k for the cnc4pc. So, Is the 5i25 card a sort of high speed proprietary parallel port? Does the ethernet version provide any better performance than the PCI/PCIE versions? Ethernet would be more work to set up tho I'm guessing.
Please Log in or Create an account to join the conversation.
20 Aug 2017 06:07 #97760
by rodw
Replied by rodw on topic CNC conversion Questions and Linuxcnc
I think the ethernet one might be a bit slower but its immaterial becasue the limiting factor is the step lengths and other step timing issues your stepper controller can accept. I got a few warnings from LCNC today when I really pushed the limits and I got a bit more velocity out of it by reducing these timing issues in my .ini file.
Its your choice which way to go. I went with ethernet because I'm building a plasma machine and I wanted to physically keep the PC away from any electrical noise. Others prefer to use the PCI/PCIe way and treat the PC motherboard as another component in their control box.
Its your choice which way to go. I went with ethernet because I'm building a plasma machine and I wanted to physically keep the PC away from any electrical noise. Others prefer to use the PCI/PCIe way and treat the PC motherboard as another component in their control box.
The following user(s) said Thank You: Kermitfrog
Please Log in or Create an account to join the conversation.
20 Aug 2017 11:39 #97771
by andypugh
You can see it that way, yes. It does step-generation on the card, so can work orders of magnitude faster than a real parallel port.
But it also supports some protocols that the p-port doesn't, most importantly a high speed serial interface that is how the 7i76 can connect to a single DB25 yet offer 5 step-dir pairs and 48 IO pins.
Replied by andypugh on topic CNC conversion Questions and Linuxcnc
So, Is the 5i25 card a sort of high speed proprietary parallel port?
You can see it that way, yes. It does step-generation on the card, so can work orders of magnitude faster than a real parallel port.
But it also supports some protocols that the p-port doesn't, most importantly a high speed serial interface that is how the 7i76 can connect to a single DB25 yet offer 5 step-dir pairs and 48 IO pins.
The following user(s) said Thank You: Kermitfrog
Please Log in or Create an account to join the conversation.
- Kermitfrog
- Offline
- New Member
-
Less
More
- Posts: 7
- Thank you received: 0
21 Aug 2017 23:06 #97840
by Kermitfrog
Replied by Kermitfrog on topic CNC conversion Questions and Linuxcnc
I suppose it depends on a lot of variables such as drives, motors, machine size etc as to whether or not these cards will provide faster cutting speeds? ...sounds like faster rapids likely in most cases tho.
Can either hall effects or optical encoders be used with 7i76, or does it have to be optical? Is there a range of pulses/rev that work best with 7i76 and Lcnc? Not finding any schematics as far as hookups or block diagrams in manual...is there a schmit trigger on 7i76 board or does one have to provide one on sensor or in between to clean up signal?
Can either hall effects or optical encoders be used with 7i76, or does it have to be optical? Is there a range of pulses/rev that work best with 7i76 and Lcnc? Not finding any schematics as far as hookups or block diagrams in manual...is there a schmit trigger on 7i76 board or does one have to provide one on sensor or in between to clean up signal?
Please Log in or Create an account to join the conversation.
22 Aug 2017 00:01 #97842
by PCW
Replied by PCW on topic CNC conversion Questions and Linuxcnc
The 7I76 encoder input has a small amount of hysteresis,
In addition, all encoder inputs have programmable digital filters
In addition, all encoder inputs have programmable digital filters
The following user(s) said Thank You: Kermitfrog
Please Log in or Create an account to join the conversation.
- Kermitfrog
- Offline
- New Member
-
Less
More
- Posts: 7
- Thank you received: 0
22 Aug 2017 00:24 #97843
by Kermitfrog
Replied by Kermitfrog on topic CNC conversion Questions and Linuxcnc
Are the input filters programmed through firmware, or can this done through linux? Didn't notice any mention of this in Mesa's manual, is there some other documentation I missed somewhere?
Please Log in or Create an account to join the conversation.
Time to create page: 0.104 seconds