electronic lead screw

luxige said:
I think I roughly follow you, and I should be able to muddle through. The flashing and parameter setting parts of this project will be the big challenge for me.

Here's a combo I was looking at:

Closed Loop Stepper Kit

Closed Loop Stepper Kit -
www.omc-stepperonline.com
Thoughts, anyone?

Yesterday I ordered Clough's interface board, a 1024p/rev encoder, Launchpad, 5v supply, display/control panel, Bud box. Here goes!
The last things to figure out are servo, driver, power supply, drivetrains for servo and encoder, nuts-n-bolts stuff.

One more point I'm a little lost on - will I need to source the connectors to hook stuff up to the interface board? From the pictures, it doesn't look like the male parts of the connectors are included…
Click to expand...

Your stepper choice sounds OK. You can correct somewhat for a undersized motor by changing the ratio if the stepper pulleys. Clough uses a 3:1 ratio with his motor. Stepper motors lose torque with increasing speed after a certain point determined buy the motor
Here is the torque curve for your motor. https://www.omc-stepperonline.com/download/34HE46-6004D-E1000_Torque_Curve.pdf
Stepper Torque Curve.JPG

As you can see, if you were operating with a 1:1 pulley set and at a lead screw speed of 300 rpm, you would have 420 N-cm of torque. Changing to a 2:1 pulley arrangement , the stepper speed would have to be 600 rpm for the same lead screw speed and the stepper torque will be about 250 N-cm and the torque at the lead screw will be 500 N-cm for a 19% increase. Going to 3:1, the stepper would run at 900 rpm@ 170 N-cm and x3 that would be 510N-cm or a 21% torque increase.

On the other end, most threading will most likely be done at low spindle speed and threads finer than 8 tpi. so you will be operating at around the 150 rpm range. Torque demands aren't all that great when threading as well.

You should have no trouble with the programming and flashing. It went without incident for me. The connectors for the interface board are included in Clough's kit. He has a video on the assembly process. (part 8, I believe)
 
kb58 said:
Since this thread resurfaced, James posted a video several weeks ago on making the display box front panel from circuit board material (copper-covered fiberglass), and etching the printing. Turned out great, though it's unclear at this time whether he plans to make them available.
Click to expand...
This is great idea. Easily done for someone without CNC capability. You could jazz up the panel by putting backlighting in to illuminate the characters.

One issue with it though are the UP/DOWN buttons. Unless someone has a 3D printer, they would be difficult to duplicate. Also, the filament material he used is rather expensive for a single project. I used round buttons made from Delrin and easily done on the lathe. I also kept them centered on the switches on th3e display board.
 
RJSakowski said:
Your stepper choice sounds OK. You can correct somewhat for a undersized motor by changing the ratio if the stepper pulleys. Clough uses a 3:1 ratio with his motor. Stepper motors lose torque with increasing speed after a certain point determined buy the motor
Here is the torque curve for your motor. https://www.omc-stepperonline.com/download/34HE46-6004D-E1000_Torque_Curve.pdf
View attachment 322758
As you can see, if you were operating with a 1:1 pulley set and at a lead screw speed of 300 rpm, you would have 420 N-cm of torque. Changing to a 2:1 pulley arrangement , the stepper speed would have to be 600 rpm for the same lead screw speed and the stepper torque will be about 250 N-cm and the torque at the lead screw will be 500 N-cm for a 19% increase. Going to 3:1, the stepper would run at 900 rpm@ 170 N-cm and x3 that would be 510N-cm or a 21% torque increase.

On the other end, most threading will most likely be done at low spindle speed and threads finer than 8 tpi. so you will be operating at around the 150 rpm range. Torque demands aren't all that great when threading as well.

You should have no trouble with the programming and flashing. It went without incident for me. The connectors for the interface board are included in Clough's kit. He has a video on the assembly process. (part 8, I believe)
Click to expand...

Thanks, RJ.
I've watched all his videos on this, but with eight-plus hours of content, and several extensive threads here, my brain filled up with info quickly. (Simply a matter of limited capacity I guess).

That's a very useful analysis of real-world torque needs. I think the 1200 oz-in may be overkill but I'm going to go with it. I can make room if I have to.
One thing I have going for me is that the gears in the quick change box that shift the leadscrew are not smashed up like most of the others, so I can just drive the feed shaft with the servo, and engage the leadscrew when needed. Two ratios, and each can run forward or reverse.
 
Well, I found another problem to ask for help with - power supply.
The driver I mentioned above is rated for 8.5A, recommended voltage is 48/60V. The Stepperonline only sells one power supply that’s in the ballpark, 48V, 8.3A (400W).
www.omc-stepperonline.com

400W 48V 8.3A 115/230V Switching Power Supply Stepper Motor CNC Router Kits

400W 48V 8.3A 115/230V Switching Power Supply Stepper Motor CNC Router Kits - This professional 400W 48V 8.
www.omc-stepperonline.com
Close enough?

Or here’s one from Automation Technologies at 60V, 10A but over triple the cost.

Opinions appreciated...
 
I bet the cheaper one will be fine. The drivers usually have a setting for max current, so you could probably use that to set it. The actual current will depend on how much torque it needs if I remember right, so you would have to push it hard to get that high.
 
Stepper drivers are protected against over voltage spikes and will shut down if the back emf exceed the maximum rated voltage for the driver. To that end, it is recommended that when using a switching power supply, the supply voltage is less than 90% of the driver maximum rating. It looks like your maximum voltage is 100 volts d.c. anything less than 90 volts should work.

The other factor is the dependence of motor torque on voltage. This is evident in the torque curve above. Generally, you will get better performance with a higher voltage. On the other hand, stepper motors tend to be more noisy with higher driving voltage and they can overheat if pushed too hard. There is a discussion of power supply selection in post 247.

I would think that the 48 volt supply should work . A 60 volt supply would be a better choice because of the greater available torque but you can achieve the same or better performance by using a 2:1 pulley reduction on the stepper. Most switching power supplies have a voltage adjust pot where you can tweak the output voltage. Mine are all around +/- 10%. Id that is the case, you would be able to increase the supply voltage to as much as 53 volts.
 
ttabbal said:
I bet the cheaper one will be fine. The drivers usually have a setting for max current, so you could probably use that to set it. The actual current will depend on how much torque it needs if I remember right, so you would have to push it hard to get that high.
Click to expand...

Thank you!
 
RJSakowski said:
Stepper drivers are protected against over voltage spikes and will shut down if the back emf exceed the maximum rated voltage for the driver. To that end, it is recommended that when using a switching power supply, the supply voltage is less than 90% of the driver maximum rating. It looks like your maximum voltage is 100 volts d.c. anything less than 90 volts should work.

The other factor is the dependence of motor torque on voltage. This is evident in the torque curve above. Generally, you will get better performance with a higher voltage. On the other hand, stepper motors tend to be more noisy with higher driving voltage and they can overheat if pushed too hard. There is a discussion of power supply selection in post 247.

I would think that the 48 volt supply should work . A 60 volt supply would be a better choice because of the greater available torque but you can achieve the same or better performance by using a 2:1 pulley reduction on the stepper. Most switching power supplies have a voltage adjust pot where you can tweak the output voltage. Mine are all around +/- 10%. Id that is the case, you would be able to increase the supply voltage to as much as 53 volts.
Click to expand...

Thanks again!
Yeah, I pretty much figured I would gear up the torque. No particular need to race the carriage up and down the bed.
I have a feeling this motor will give me plenty of performance headroom, and if not, I can change the reduction with another pulley and belt.
 
luxige said:
Thanks again!
Yeah, I pretty much figured I would gear up the torque. No particular need to race the carriage up and down the bed.
I have a feeling this motor will give me plenty of performance headroom, and if not, I can change the reduction with another pulley and belt.
Click to expand...
At a maximum of 5,000 rpm and a pitch of 8 tpi, even at a 3:1 ratio, that's still 147 ipm. The maximum feed rate for the Clough system is 5mm/rev. if you use the metric thread mode. It would be crazy to run at that setting at my maximum spindle speed of 2400 rpm. Actually, I would be at twice the maximum stepper rpm anyway.
 
RJSakowski said:
Your stepper choice sounds OK. You can correct somewhat for a undersized motor by changing the ratio if the stepper pulleys. Clough uses a 3:1 ratio with his motor. Stepper motors lose torque with increasing speed after a certain point determined buy the motor
Here is the torque curve for your motor. https://www.omc-stepperonline.com/download/34HE46-6004D-E1000_Torque_Curve.pdf
View attachment 322758
As you can see, if you were operating with a 1:1 pulley set and at a lead screw speed of 300 rpm, you would have 420 N-cm of torque. Changing to a 2:1 pulley arrangement , the stepper speed would have to be 600 rpm for the same lead screw speed and the stepper torque will be about 250 N-cm and the torque at the lead screw will be 500 N-cm for a 19% increase. Going to 3:1, the stepper would run at 900 rpm@ 170 N-cm and x3 that would be 510N-cm or a 21% torque increase.

On the other end, most threading will most likely be done at low spindle speed and threads finer than 8 tpi. so you will be operating at around the 150 rpm range. Torque demands aren't all that great when threading as well.

You should have no trouble with the programming and flashing. It went without incident for me. The connectors for the interface board are included in Clough's kit. He has a video on the assembly process. (part 8, I believe)
Click to expand...


That chart doesn't make sense for a 9Nm stepper. that is showing .7Nm at peak?

anyway, I'm using a 2.2Nm hybrid stepper direct drive on a 2mm pitch leadscrew and it happily stalls out my spindle motor before it faults. I've threaded hardened shafts and the insert is more of a problem than the stepper. I'd guess that Clough's firmware would also stop driving the lead screw when the spindle stopped. I guess if you are taking huge cuts and or cutting huge threads you might need such a beast but for < 2mm pitch I can't see much need to go bigger. Are you planning on cutting acme threads or something?

Finally consider that motors don't just start stop instantly, there should be an acceleration curve (or trapezoid). I doubt the controller can compensate for crazy spindle speeds and the sync issues decelerating at the end of your thread. The larger the motor and the more inertia it has which makes that acceleration curve flatter. at some point it can't keep up no matter how much torque you have unlike a gear train which just breaks when you run it too fast. everything is a trade off ;)
 
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