Help with motor to dive platter

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thelace43
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Help with motor to dive platter

Post: # 64008Unread post thelace43
Tue Jan 23, 2024 3:48 pm

Hello trolls, I am trying to figure out what I need to spin a platter. I made a mono embossing head that sounds great, but my direct drive turntable does not have enough torque to cut without warble until it gets a bit closer to the center. I have some NEMA stepper motors, but their max rpm is not enough to use with a belt around the rim of the platter. I was thinking I could buy a larger motor pully, but besides the trouble of removing the current one, I don't know if that is the best option, and I am having trouble finding one. I was thinking of a servo motor, but have no experience with them. Thank you for any help!!

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markrob
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Re: Help with motor to dive platter

Post: # 64009Unread post markrob
Tue Jan 23, 2024 8:11 pm

Hi,

What RPM are you needing to run the steppers at? What size and spec motor are you using? What are you using as a driver and what voltage are you powering the driver with. If you can afford a full on servo, that would be best, but if this is a hobby build, you should be able to get decent performance from a belt driven stepper using the typical Trinamic (e.g. TMC2209) drivers out there.

Mark

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thelace43
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Re: Help with motor to dive platter

Post: # 64010Unread post thelace43
Tue Jan 23, 2024 9:07 pm

Hey there, thanks!
I was experimenting using a NEMA 23 with a TB6600 driver. 12 volts .. Does that make a difference? Using an arduino, I dialed the speed as high as it would go, but it got the platter to spin at around 15rpm.

What exactly do you mean by a "full on servo"? Is it less than 500 bucks? Is this not a hobby build if it costs a lot? I guess it's more of a prototype. I can not afford much at all, but this is all I spend my money on, so I'll save up. Thank you so much for your help!

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markrob
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Re: Help with motor to dive platter

Post: # 64011Unread post markrob
Tue Jan 23, 2024 11:23 pm

Hi,

That driver might be ok. Its not a full micro step drive, but at 32 pulses per step, it might not be too noisy. What is the model number of the stepper motor are you using? What is the motor rpm you need to reach 45 rpm platter speed?
Can you upload the Arduino code you are running?

Mark

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piaptk
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Re: Help with motor to dive platter

Post: # 64018Unread post piaptk
Thu Jan 25, 2024 3:45 pm

If you are in the US and want to buy an off the shelf solution i sell Jed’s awesome wow and flytterless belt drive motors kn the US (he sells them in the rest of the world and i can connect you). DM me if you want one.
I Buy/Sell/Restore Vintage Machines/Parts and Provide Phone/In Person Tech Support
www.MichaelDixonVinylArt.com
www.LatheCutCamp.com
www.RecordLatheParts.com
www.MobileVinylRecorders.com
www.LatheCuts.com

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thelace43
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Re: Help with motor to dive platter

Post: # 64026Unread post thelace43
Fri Jan 26, 2024 1:46 pm

DM'ed!!

As for the stepper motor, it looks like it has a .5" pully, so I used this cool site (blocklayer.com/pulley-belteng) and got 1,080 RPM for 45 RPM. The motor says P/N 127DE03050 ... 23KM-K035-P7V ... NO. T7505-03

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markrob
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Re: Help with motor to dive platter

Post: # 64028Unread post markrob
Fri Jan 26, 2024 11:50 pm

Hi,

We are getting somewhere.

The spec for the motor I could find on line was not complete, but it indicates is a 2A, 3.2V winding. That should be able to provide plenty of torque with a 12 Vdc or better driver supply. In fact, I would say its vast overkill.

1080 RPM is pretty fast due to the large ratio you are using. That puts some strain on how fast you need to apply pulses to your stepper driver. At 32 micro steps per rev, you would need to need to pulse at 115Khz to reach 1080 rpm. That's pushing what to Arduino timer can do and still provide good speed resolution. Running a 4 or 16 setting would lower the max pulse rate at the expense of more noise and torque ripple.

I would go with a larger pulley to reduce the motor speed into the 300 rpm range. That implies about a 6:1 ratio or a 2" diameter pully. This does reduce the torque at the platter, but you have so much reserve, that I don't think it will be an issue.

I prefer the Trinamic TMC2209 drivers as they have a cool feature that internally up scales the input pulse stream to 256 micro steps at 4 or 16 pulses per step setting. This provides very smooth near sine wave drive and results in very low noise and ripple. With the combination of a larger pully and running at 16 pulses per step, the pulse rate drops from 115Khz down to 16Khz or 4 Khz at 4 pulses per step. You can do the same setup with your current driver and see if the coarser micro step setting results in too much noise and ripple.

You didn't provide your Arduino code, so I can't comment on how well optimized it is for this application. Typically, I have found that all of the standard stepper libraries have too much time jitter for this application. I direct write to the timer hardware and connect my step input to the dedicated Arduino timer pin. This allows me to write a few registers and then let the hardware manage the pulses with no additional software overhead. In this mode, the timing jitter is in the ns. range as opposed to us. range for software assisted pulsing. If you are interested, I can provide some sample code to demonstrate this.

Mark

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jjwharris
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Re: Help with motor to dive platter

Post: # 64030Unread post jjwharris
Sat Jan 27, 2024 3:54 pm

I use leadshine ISV57 servos, they are the quiestest I could fine and provide quite a lot of torque, i recently used one to spin a 800mm platter with 100kg+ sitting on them. (https://www.youtube.com/watch?v=lUr4jF4bhaI)

At this point I think they may be overkill for the lathe. The benefit they have is you can feed that 100-150khz from an AD9833 and they are very quiet.

I did cheap out with a non-leadshine servos at the start, they can work, but you will need to program them with a USB->Serial converter and mess with the setting to get the motor noise down. Whereas the leadshines tend to be plug and play

I'm currently running my playback turntable with a Nema17, AD9833 for signal generation and a TMC2209 driver.

I'm hoping to implement this motor system into a record lathe soon.

You should be able to get high speed from the TMC2209 and AD9833 - the issue with high speeds with a stepper is losing torque and you tend to get motor whine

I'm thinking a low gearing ratio may benefit stepper drives as they provide plenty of torque and there's a sweet spot where they are virtually silent at low RPMs

I've been meaning to experiment with BLDC motors driven by a SimpleFOCMini.

I'm interested to know if there is a more precise signal generator than the AD9833

Another mention is that I have found using a higher voltage with the TMC2209/Stepper/AD9833 tends to let you reach higher speeds. I implemented this system on a turntable that goes from 1rpm to 100+rpm. It required a lot of decoupling to remove the vibrations, but it also provides reasonable torque.

Anyways, here's a video of a motor with UART control.

https://www.youtube.com/watch?v=LhxmnwLtlFw

And here's a video with no UART, but connected to a platter. The gearing ratio is about 9:1 but that's a guess, it's using the original Project Pulley with the inner platter pulley.

https://youtube.com/shorts/7UsAT1Rqd5E?feature=share
Record Lathe Embossing Supplies - http://www.supplies.johnnyelectric.co.nz/

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thelace43
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Re: Help with motor to dive platter

Post: # 64331Unread post thelace43
Thu Mar 07, 2024 9:42 am

I have been coming back to this thread every so often when I have time and half a mind to spend some money, but I am not even paycheck to paycheck at the moment. Just wanted to say thank you for all the great info, I really really appreciate it.

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