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Gear ranges
Posted: Thu Nov 16, 2017 8:11 pm
by Dave_C
I've just printed out the Centroid manual before I attempt to convert my very successful Lathe conversion from Mach 3 to an Acorn setup.
Here is my question: How does the Centroid software account for the fact that I have 9 gear ranges to choose from? I use the 1,000 RPM range the most but I have 1,400 available when I need it and I also need some of the lower gears for large diameter threading.
Dave C.
Re: Gear ranges
Posted: Thu Nov 16, 2017 8:59 pm
by DICKEYBIRD
The spindle setup tab in the Config Wizard has low, medium & high speed ratios already but if you need more I'm guessing it will require some programming of the PLC.
Re: Gear ranges
Posted: Thu Nov 16, 2017 9:09 pm
by frijoli
Dave_C wrote: ↑Thu Nov 16, 2017 8:11 pm
I've just printed out the Centroid manual before I attempt to convert my very successful Lathe conversion from Mach 3 to an Acorn setup.
Here is my question: How does the Centroid software account for the fact that I have 9 gear ranges to choose from? I use the 1,000 RPM range the most but I have 1,400 available when I need it and I also need some of the lower gears for large diameter threading.
Dave C.
There is only 3 ranges I am aware of that are in Acorn.
Most people use a variable speed motor and 1 to 3 physical gear ranges. That way you can have adjustable/constant surfaced speed.
Your gear box probably has 3 gear sets with 3 speeds in each. With a variable motor you pick one of the three main gear sets, and then let the motor do the work from there.
Re: Gear ranges
Posted: Thu Nov 16, 2017 10:55 pm
by martyscncgarage
Dave_C wrote: ↑Thu Nov 16, 2017 8:11 pm
I've just printed out the Centroid manual before I attempt to convert my very successful Lathe conversion from Mach 3 to an Acorn setup.
Here is my question: How does the Centroid software account for the fact that I have 9 gear ranges to choose from? I use the 1,000 RPM range the most but I have 1,400 available when I need it and I also need some of the lower gears for large diameter threading.
Dave C.
No VFD Dave?
I had a Bridgeport Romi EZ Path with the Centroid Control on it. It was a gear head. BUT it was fitted with a VFD. 3 Gear ranges were chosen, (Low, Medium & High ranges) then the VFD would control the speed within those ranges. You would then use the SPIN HI, SPIN MED, SPIN LOW buttons on VCP.
Add a spindle encoder at 1:1 and you are rockin'!
I have a hunch you have a single phase motor?
Marty
Re: Gear ranges
Posted: Fri Nov 17, 2017 3:25 pm
by Dave_C
Marty,
Nope, I have a 2 HP 3 phase motor with a 2HP VFD. So I'm good with just using three of the gear ranges as that is about all I use now! I see no reason to complicate the issue now that I have read the above post. I could still use the spindle manually if there was something that did not fit in the 3 ranges.
IE: Big diameter part needing slow RPM for outer edge turning. I have my VFD set for constant torque so maybe not a problem?
Common sense I guess, I just had not thought it through and I was still thinking in terms of how Mach 3 handled the gears.
Re: Gear ranges
Posted: Fri Nov 17, 2017 6:54 pm
by Centroid_Tech
Dave,
If you wanted to use all 9 gear ranges, you could but as DICKEYBIRD stated, the PLC program will have to be modified in order to take all of those gear ranges into account. The base PLC program has logic for 3 ranges. In addition to the modified PLC program, you will also have to create a custom macro for each individual spindle gear range as the control needs a way to determine which gear range it's in. You can do that either via an input or via a macro. Since you are limited on the amount of inputs with the ACORN, the custom macro is the way to go. On top of that, you will also need to associate parameters for the gear ratio for all of those gear ranges so that the Centroid control can supply the appropriate voltage to the VFD. The base PLC program uses parameters 65 and 66. Thanks.
Re: Gear ranges
Posted: Sat Mar 03, 2018 5:36 pm
by Muzzer
My Shizuoka has a 2 speed spindle with solenoids to select high or low ratio - and switches to indicate which range is currently selected. Rather than having to manually select the range and let the Acorn (in my case) see this from the switch inputs, is there a way to use one or two of the outputs to select the correct range automatically? It should be possible to determine which range is required from the demanded speed and enable the correct output. I can probably afford to use more of the outputs than the precious inputs, so this solution would win on two counts.
I also have a spindle encoder that is made of 2 Hall effect geartooth proximity switches picking up on the main spindle gear, as this was the best solution I could find to the tricky problem of detecting spindle speed directly. Do I need to process the signals to generate complementary A and A bar, B and B bar signals for the spindle encoder input? If so can you suggest a suitable solution?
Thanks for your support!
Re: Gear ranges
Posted: Wed Mar 07, 2018 6:40 am
by Muzzer
Keith - any suggestions on the gear selection? Would I need to get into PLC programming to automatically select the correct gear?
Thanks
Re: Gear ranges
Posted: Wed Mar 07, 2018 8:21 am
by diycncscott
Actually, the base PLC has allocations for 4 gear ranges. Low, Med Low, Med High and High with the assumption that "High" is 1:1
The time it would take to change the PLC and/or VCP would depend on exactly what the requirements were. Do you need a PLC input to verify each range? That would take at least 4 inputs. Do you just want to use an M code to switch ranges? M codes and Aux keys for each range? If you don't have inputs to represent each range, what range should be assumed at start up?
The PLC program is ascii text and can be found in the c:\cnct directory with an extension of .src. The PLC Programming Manual can be found here:
http://www.centroidcnc.com/downloads/CN ... Manual.pdf
Re: Gear ranges
Posted: Wed Mar 07, 2018 9:21 am
by martyscncgarage
Muzzer wrote: ↑Sat Mar 03, 2018 5:36 pm
My Shizuoka has a 2 speed spindle with solenoids to select high or low ratio - and switches to indicate which range is currently selected. Rather than having to manually select the range and let the Acorn (in my case) see this from the switch inputs, is there a way to use one or two of the outputs to select the correct range automatically? It should be possible to determine which range is required from the demanded speed and enable the correct output. I can probably afford to use more of the outputs than the precious inputs, so this solution would win on two counts.
I also have a spindle encoder that is made of 2 Hall effect geartooth proximity switches picking up on the main spindle gear, as this was the best solution I could find to the tricky problem of detecting spindle speed directly. Do I need to process the signals to generate complementary A and A bar, B and B bar signals for the spindle encoder input? If so can you suggest a suitable solution?
Thanks for your support!
I'm trying to picture what you have.
If your head is two speed, then you need one input. In one position it is high and in the other it is low.
If the transmission is selected by solenoids they are two individual solenoids not one? (in/out?)
Centroid recommends and supports a line driven differential encoder belted at 1:1 with a timing belt. 2000 count.
It uses both the index pulse and the full encoder counts.
I just wanted to give you some sort of response with my limited knowledge.
Marty