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Spin High/Med/Low

Posted: Mon Jan 03, 2022 3:49 pm
by Philtrueman
Can someone tell me, what is the function of these buttons on the Acorn VCP?
I have a 4 speed belt drive pulley reduction for the spindle speed. Can i program different spindle speeds to suit the different spindle gearing ratios?
The only other option is to fit a larger spindle DC motor so that i can have only one drive belt on my Boxford 250PC lathe.

Re: Spin High/Med/Low

Posted: Mon Jan 03, 2022 4:12 pm
by tblough
CNC12 has provision for up to four spindle gear ratios. This allows for high/low gearing like on a Bridgeport knee mill, or a lathe with a gear-head spindle. Centroid will apply the appropriate gear ratio and display/command/use the correct spindle speed.

The issue is how to tell CNC12 what gear you are using. One way it to add microswitches to the transmission on the device and connect these to unused inputs, and then customize the PC to react to those inputs.

Another way is to use manual switches or buttons (like the VCP) to manually tell CNC12 when you have changed gears. This is the cheap and easy way, and for some, all that they need.

Look at parameters 65-67 in the mill or lathe operator's manual.

Re: Spin High/Med/Low

Posted: Fri Jan 14, 2022 11:29 am
by Philtrueman
I have had a look at parameters 65,66,67 Do i enter the drive reduction ratio in these fields? My lathe has 4 belt drive reduction speed ratios. How do i enter another 4th speed ratio to make it 4 speeds? I also tried to enter the gear ratios in the low and medium boxes but it will not allow any numbers other than 1 or 0.

Re: Spin High/Med/Low

Posted: Fri Jan 14, 2022 12:48 pm
by cncsnw
The highest range uses the maximum speed you set on the Control Configuration screen (or on whatever Wizard page provides the value for the Control Configuration screen). There is no gear-ratio parameter for the highest range.

Parameters 65, 66 and 67 are the speed fractions for lower gear ranges. These lower ranges are generally called low; medium-low or mid-low; and medium-high or mid-high.

For example, if in your lowest gear the spindle runs at 1/8 of the speed it would be running in high gear (for the same motor speed), then you would set Parameter 65 = 0.125.

Note that actual motor RPM is generally not relevant. If even your highest gear has some speed reduction (or increase) between the motor and the spindle, it is the spindle speed (not the motor speed) that you put on the Control Configuration screen. Parameters 65, 66 and 67 are fractions of the high-range spindle speed, not of the motor speed.

Re: Spin High/Med/Low

Posted: Fri Jan 14, 2022 2:21 pm
by cnckeith
fyi.. for anyone else reading this thread the wizard spindle setup menu supports up to three ranges,
and you can use the CNC12 parameters if you have more than three ranges.
spindle range.PNG

Re: Spin High/Med/Low

Posted: Tue Jan 18, 2022 7:59 am
by Philtrueman
cncsnw wrote: Fri Jan 14, 2022 12:48 pm The highest range uses the maximum speed you set on the Control Configuration screen (or on whatever Wizard page provides the value for the Control Configuration screen). There is no gear-ratio parameter for the highest range.

Parameters 65, 66 and 67 are the speed fractions for lower gear ranges. These lower ranges are generally called low; medium-low or mid-low; and medium-high or mid-high.

For example, if in your lowest gear the spindle runs at 1/8 of the speed it would be running in high gear (for the same motor speed), then you would set Parameter 65 = 0.125.

Note that actual motor RPM is generally not relevant. If even your highest gear has some speed reduction (or increase) between the motor and the spindle, it is the spindle speed (not the motor speed) that you put on the Control Configuration screen. Parameters 65, 66 and 67 are fractions of the high-range spindle speed, not of the motor speed.
Thank you for explaining the settings. I understand how it works now.

Re: Spin High/Med/med-Low/Low

Posted: Sat Jan 22, 2022 4:33 pm
by Philtrueman
I have changed the parameters in number 65 Low 66 medium/low and 67 medium/High to what the gear ratios are on my "4 speed " lathe but in the utility wizard it still only shows Low and medium it is missing the medium low box. The medium/high box is missing. Is it possible to change this in the software?

Re: Spin High/Med/Low

Posted: Sat Jan 22, 2022 6:19 pm
by tblough
The answer is 3 post above.

Re: Spin High/Med/Low

Posted: Sun Jan 23, 2022 8:29 am
by Muzzer
One thing I found confusing was how to configure the ratios if you have only 2 speeds - where do you define the low ratio? The high is the "straight through" 1:1 ratio ie fairly obvious but for the reduction ratio, do you specify the lowest ("low") or the second highest ("medium") for that purpose? If you choose the "low" ratio, does it matter how you configure the intermediate ratios? I forget how I set mine up in the end but I do recall that it involved some experimentation.

On my machine I have pneumatic solenoids to move between the 2 ratios, as well as microswitches to tell me if the gears have fully meshed (based on the actual position of the solenoids). That avoids grinding the gears if the gears have not fully meshed. The M3 and M4 macros check which ratio is required for the demanded spindle speed and don't exit until the correct ratio has been selected and fully meshed. I briefly pulse the VFD before doing a retry, if meshing wasn't achieved at the first asking. Obviously if you change the spindle speed subsequently without issuing another M3 or M4, the ratio will remain unchanged.

Re: Spin High/Med/Low

Posted: Sun Jan 23, 2022 9:04 am
by tblough
Doesn't really matter since it's up to you to configure the inputs to tell CNC12 what range you are in. If you have two ratios, low can be any of the three. Just be sure to use the same range when defining the input.