Lockdown turntable and lathe - a DIY project

[basssss]

Hi to all,

Some photos of my progress.... Pentlandsound Lathe and Estrada stereo cutterhead. I'm far to start testing.... a lot of things to learn before. The first tests will be with Steel roland blades and plastic dishes ( any othe recomendation ? ).

Thanks to David and Craig, this project is possible.

I'll keep you updated.

Greetings.

[Lichar]

Hi everyone! Anobody know how to set the speed of my motor to make it turn as the creator's? I know it must fit with the centimeters in the vinylburn software but i dont understant what value change...
Sorry for my bad english, greeting from France

[pentlandsound]

Hi Lichar - you'll need to review and possibly alter a couple of constant values in the Vinyl Burn software. Find the GenMethods project and go to the General.cs module. Within this module are several constants used by the program. The only two you might need to change are:

public const int StepsPerRev = 200; // stepper motor FULL steps / rev
public const decimal CmPerRev = 0.1M; // leadscrew pitch in centimetres

Hope this helps!

[mrmoo]

I have used the default preset (Low quality)

Your pictures look awesome. They are shiny as you have used PLA...
How much and type of infill did you use? I am worrying about echo effects from low infill.

[Lichar]

Hi everyone, my program is working fine, thank you to your help.
Now i have a question, is it possible to put the stylus only on the cones, without the styulus holder? The stylus would be put in a cube, fixed to the cones
Tell me if you cant understand, i'm french.

[tragwag]

Hi everyone, my program is working fine, thank you to your help.
Now i have a question, is it possible to put the stylus only on the cones, without the styulus holder? The stylus would be put in a cube, fixed to the cones
Tell me if you cant understand, i'm french.

You need the armature (the small angled linkage) to properly move the stylus itself.
it's all super important for stiffness, low moving mass, and proper angles for groove geometry.
keep in mind with a DIY head you're basically reverse engineering for the extremely well established parameters of record playback.

[dameng]

Hello, can you send this 3D printing modeling file? Thank you very much

[lulu]

Hi!

I am building very similar construction, now I am trying to use stepper for platter drive. I tried to PM you, would it be possible to have your arduino sketch for the platter motor control please? I have found all the other files on github wich is great, but the platter mottor control is not there.

Thank you!

Lukas.

[pentlandsound]

Lukas - please see PM.

All - my latest turntable platter driver script is uploaded to Github, in https://github.com/dn784533/lathe_guide/tree/main/Arduino/TT_2023.

David

[Fattcamp]

Hi all,

I'm new to the forum but have been doing lots of research and think I'd like to take a crack at this pentlandsound lathe with hopes of a stereo cutterhead such as the build by basssss (Thanks Estrada & grooveguy!)

From what I gather, and reading the newbie forum/starter guide, most lathe cuts/embossing are in mono with the exception units such as Souri's T560. I'd really like to achieve some decent quality stereo embossing if possible.

Just a few questions to get started:

• What is your experience with the Estrada stereo cutting head based on grooveguy's design? I'm wondering if I should I stick more closely to the pentlandsound build?
  • I'm concerned some 3d printed parts may need to be modified, such as the cutterhead (perhaps basssss has some insight on this regarding the Estrada.
• I'm in Western Canada and trying to source out parts for this lathe build. Some parts are overseas and some are currently unavailable. Wondering if you guy have any recommendations for suppliers/vendors closer to home in Canada (or the US)?
  
  • In particular, the Linear rail (KR2001) does not seem to be currently available and I know the 3d printed parts from this build were specific to these models.
  • The TEAX-19C01-8 coin exciters seem to be out of stock everywhere.
  • The the Z-axis bearing & dashpot new prices are bonkers as well!

(If my post is better suited outside of this thread, please let me know. I know I want to base my build from this same one but don't want to ruffle any feathers as I'm new to the forum.)

Thanks guys,
Dave

[markrob]

Hi,

You don't really get good stereo separation via embossing. The reason why is not totally clear. The theory is that the embossed grooves tend to be U shaped and this makes the playback stylus ride in the bottom of the groove. I'm not 100% sold on this explanation and I think more work could be done to investigate. However, as of now, don't expect great results for stereo embossing. Embossing is the easiest and lowest cost most foolproof method to start with, but cutting will give the best results with the widest compatibility on playback. I would start embossing, get comfortable and then move to cutting if you can justify the cost. Just a matter of paying for the diamond cutting stylus.

Mark

[Fattcamp]

Thanks for the info. I wasn't sure if there was something different required with the cutterhead design/wiring itself other than switching out the stylus for attempting stereo vs/mono embossing or cutting, or if you just send a mono signal from the PC instead by converting the audio before-hand. That's why I was debating the differences between the Estrada head and the the one from this (pentlandsound) build.

Does that mean I can ultimately stick with the build guide from David and simply swap out the sapphire embossing stylus for a diamond cutting stylus down the road without further cutterhead modification? I hope that makes sense. I'm trying to keep the cost down as some of these parts are quite expensive and if (when) I get this thing embossing, work on upgrades down the road.

One other thing: Does anyone have thoughts on the alumide vs a more standard filament as far as pro's/cons sound-wise? I like the idea of alumide in the build but don't have my own 3D printer and want to make the best choices before getting the printing company to do their thing. I see some folks on the forum printing with whatever the standard filament but curious if there are any audio changes with the final product due to resonance or anything like that.

Dave

[markrob]

Hi,

Glad you find that useful. Yes, you should be able to do the standard build and start with an embossing stylus as long as the stylus holder is designed for the standard Presto long or short shank. One nice thing is that if you wear out a cutting stylus, you can turn it around backwards and it becomes an embosser. A purpose fabricated embossing stylus like the type Mike Dixon and others sell, will probably perform a bit better, but the backwards trick works well once you get it dialed in.

You can send a stereo signal to the head and take what you get in terms of stereo separation. You can also pre-process the stereo in Mid-Side mode and boost the side channel and convert back to stereo to get a bit more separation , but there seems to be a point of diminishing returns. Best to do a true mono mix (rather than fold the stereo to mono) and emboss that.

Never tried the high tech FDM filaments myself. It would probably be better, but I'm not sure if the extra cost justifies it. You might want to think about getting a low end Creality Ender or something like it. By the time you pay to have the parts printed, you might have paid for the printer. Once you have one of these, you will find so many uses you will wonder how you ever got by without one. It takes a bit of a learning curve, to get good at printing and CAD modeling, but its worth the time (I love Fusion 360). If you are going down the DIY rabbit hole, you will be spending quite a bit of time any money to get up and running, but if you stick with it, you will really happy you did. Just don't expect to compete with a Scully or Neumann and you will be fine.

Mark

[kugelblitz]

By the time you pay to have the parts printed, you might have paid for the printer.

I went the other route on this and just have everything done, there's loads of semi-pro guys/girls in love with their machines offering their services and i find they do a great job for relatively cheap.

[Fattcamp]

Thanks for the additional info guys. I've got a co-worker of mine printing the parts with PETG filament and everything seems to be going quite well. He did have a question about the "Torque Tube with 18deg Tilt.FCStd" that I converted to STL using freeCAD default export settings.

The torque tube is quite small and he was wondering if anyone had issues with printing it without further tweaks. I reached out to inspector77 but figured I'd ask here if anyone had any thoughts or advice while it was on my mind. I'm starting with the printed parts and will be acquiring the rest as close to David's build instructions as possible.

Dave

[Fattcamp]

Hey guys. I'm still acquiring everything needed for this build but have a few things so far. I've got the 3d printed parts which were printed by a coworker of mine, Arduino Uno, V-Slot, vertical micrometer, linear slide and the dashpot which is in transit. I still need to get the electronic components and the miscellaneous parts. I'll be putting the v-slot together tonight with the linear slide.

I'm Not sure if the motor mount for the Nema 17 will work being as close as it is on the rail, but thought it was worth a shot to try and get everything operational and take things from there. I'll be getting a TC2208 stepper driver to keep things as close as possible to the build.

Questions regarding the motor: I'm going to grab a Nema 17 rather than Nema 14 since my linear slide came with the motor mount for the 17. Are there any disadvantages to the 17 for this build regarding noise or anything else? Also, I'm new to working with motors... so what is recommended as far as voltage/torque etc for the slide to do it's work with ease? There are so many variants of the Nema motors. I'll be going with the Nema 17 unless the 14 is better for some reason but I believe this is just the spacing for mounting the motor itself. I'm aware that I'll need to step down the voltage either way, but I've been scratching my head a bit as to how much juice the motor needs to have for moving the linear slide.

Either way, excited to get more parts and see how far I can take this build!

Dave

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[Thelatheofus]

I'm not an expert of stepper motors so double check this. From what I understood with stepper motors the voltage will change the torque : they operate within a certain range (my nema 17 works from 12 to 24V by example), the higher the voltage the higher the torque. For our purposes we don't need much torque but I guess the higher the torque the better (not sure how it translates to noise or missing steps though)
The problem with stepper motors is that they are noisier than DC motors, and their pitch changes with the speed of rotation. The lower they rotate the lower the rumble, and lower noise usually propagates more through the machine than higher ones. So you need to decouple the motor from the machine as much as possible and use a belt. To get around the noise issue you can also think of gears, so the motor can operate at a higher speed to provide the same rotation of the screw of your linear rail.
Also you should get the parts of the cutting head printed in alumide (like the author mentionned) or you'll never be able to cut higher frequencies

[markrob]

Hi,

You should be able to get a handle on the required torque if you attach a lever off of the feed screw shaft so its parallel to the surface of the table. Hang weights off of the end end of the lever see how much it takes to break free. Measure the length of the lever and the torque is the weight (force) times the length (watch your units e.g. Kg-cm). I would double that number for safety. I suspect if a NEMA 14 worked, so too will a 17. The torque ranges do overlap quite a bit. For a constant current stepper drive like the Trinamic 2209's, the current sets the torque. However the supply voltage sets the speed at which the torque decreases due to the effect of motor back EMF. At very low RPM, the stepper will reach full torque as the motor back EMF is low as compared to the supply voltage. In this application, you have speed ranges of up to 100:1. So, the issue will be during lead out and lead in (4 LPI during lead out vs 300 LPI during your cut). Sizing steppers can get complicated, but in general, you want to make sure you choose a stepper that meets the torque requirements (look at holding torque to get in the ballpark). Next you want to make sure it is wound to perform at your available power supply voltage at the speed you require. Select a motor with a current rating that matches the driver. The 2209 can drive about 1.4 Arms without shutting down thermally. Now look at the DC coil resistance and multiply this by the drive current (1.4 Arms) make sure this voltage is about 1/5 to 1/10 of your supply voltage ( ~2-5 V). This gives you headroom for high speed operation. Fortunately, most 3D printers these days are running 2209's and 12 or 24 Vdc supplies, so the cheap StepperOnline motors you will find have been wound to work with this combo. I have developed an Excel spreadsheet to help with evaluating steppers. If you are interested, I can post it. Hope you find this helpful.

Mark

[Fattcamp]

Thanks for the info Mark! I'm not going to lie... some of that went over my head but I'll just need to take my time parsing the info to sort things out. If you could post the stepper eval spreadsheet, it would be much appreciated! I think I'll temporarily mount the stepper to the rail itself just to get everything up and running and once operational, use a belt & pulley and mount it elsewhere on the v-slot as per Dave's design. My airpot showed up finally so just need to get a few odds & ends to get things happening.

Is there any benefit to swapping the 2208 stepper driver for the 2209 without having to drastically alter code for the Arduino driving the motor for the rail movement? I was trying to keep things as close to the build as possible on that end but didn't know if there were any glaring advantages/disadvantages over those 2 stepper drivers. I'll be using the Arduino Uno R3.

Thanks,

Dave

[markrob]

Hi,

The 2208 and 2209 are very similar. There are some differences, but if the 2208 works for you, I would not change to the 2209. Here is a nice rundown of the differences.

https://www.utmel.com/components/tmc2208-vs-tmc2209-what-differences-is-between-them?id=1378

Here is my spread sheet with values for a 17HS24-2104S stepper. You can use values for any stepper that you want to eval and save to a new file name. The important parameter besides the data sheet info is the max motor speed. Once you enter that number, you will see the torque and required power supply needed to reach that at the entered speed. If its larger than the chip is capable of, then torque will reduced. Note that this is the torque at the motor shaft. What you get will depend on any gear ratio used between the motor and the load. This is where is gets interesting. High ratios give you more torque at the load but require higher shaft speed. So running a high ratio, might not be the best idea. You can also see if the winding for a selected motor is able to run at the torque it is capable of using the limits of the driver supply voltage and max rms current.

Stepper Calcs 17HS24-2104S.zip

Also, here is a formula to calculate the required stepper motor rpm given platter speed, desired lpi, and gear ratio:

Stepper RPM = (Platter RPM / Desired LPI) * Motor revs/in

For example given a leadout of 4 lpi at 45 rpm platter speed and an overhead that needs 3 stepper shaft revolutions to move 1 inch

requires a shaft rpm of 33.75 RPM

Mark