Ritter's DIY lathe and 45/45 cutter head

[Ritter]

Hi all,

I've been lurking here for some time, and I've been really inspired by some of the awesome builds out there.

However, now it's time to start my own build. So, here goes. The intention is to keep this topic updated as I progress the build.


Lathe

I don't have an existing lathe, or access to one, so I'll be building my own. The first target for the lathe will be an existing mono cutter head, followed (hopefully) by a stereo cutter head.

To get the lathe off the ground I thought it best to get the control electronics done first. So, I spent some time over the last few weeks building a "demo" to get the stepper working with an Arduino clone. I've opted for a "remote control model": the Arduino will be connected to a PC and receive commands (via USB/serial) from some software that will run on the PC. The arduino will be responsible for timing and driving the stepper, something that a PC may have issues with (given it's also busy doing other things; context switching and interrupts).

1-lead-screw.jpg

I read somewhere that a directly driven lead-screw might not be ideal either, because it introduces sound into the cutting process, but I'll start with this and can always change to a belt-driven version later.

I don't have the experience to build something in metal, so I'll be using my favourite material: wood (it's very forgiving). The following picture shows the initial frame I built recently. It fits nicely over my 301, which I'm hoping will have sufficient torque for cutting.

2-lathe-frame.jpg

Cutter head

The cutter head (initial, unfinished design below) will be 45/45 stereo head, using a neumann torque tube and vspring. The body will be crafted in 6mm metal; I'll get a friend to help out with that part. I'll be using a pair of AuraSound Cougar (extended range) drivers, and some kind of concical shape to take the movement from the driver to the torque tube. I see people using little metal funnels... looks like a great idea.

Following EpicenterBryan's advice, I've opted to get a ready-made torque tube from ROLANDJAYS. Looking forward to getting that in the post one of these days. I doubt I could have engineered one myself. When that arrives I'll be able to finalise the head design and get that body built.

3-cutter-1.jpg

4-cutter-2.jpg

The design is missing a back plate for the piano wire anchor to the torque tube. I'll handle that when I update the design.

More updates soon (hopefully).

[CountMoogle]

I love it! Keep it up, seeing another build in progress give me determination to continue working on my build.

[Ritter]

Hi,

Time for a quick update. So many things have happened since the last posting.

I managed to obtain an old RCA mono cutter head, and have outfitted it with an embossing needle. The lathe is now running (mostly) and today I managed to emboss my first record onto "record shaped" sheets of acetate. Man, what an experience as it traces new grooves into the plastic. I won't upload the sound, as it's pretty poor, but I'm on the way. I'm keen to get into cutting, so may try a sapphire or diamond stylus with something a bit stiffer next (those acetate sheets are too flexible).

In the meantime I've received the torque tube in the post and am finishing up the stereo cutter head design. I'll start the build on this over the next few weeks. Two photos below, one of my current experimental set up, the other of my first record.

2017-02-12 17.54.26.jpg

2017-02-12 17.54.39.jpg

Cheers!

[Ritter]

Just as an afterthought, it's worth noting that the Garrard 301 seems to have plenty of torque for embossing.

[Soulbear]

Hi There,

Just as an afterthought, it's worth noting that the Garrard 301 seems to have plenty of torque for embossing

How fascinating, I found the Garrard 401, which shares the 301's Motor to be well "Under-Nourished" in the very subjective, non-objective "Stalling the Platter with a Finger" Test. Hence my decision to go the Technics SP10 Route. Perhaps I maybe could have been less hasty and shown a little more patience. Before "Trading" this Turntable, I should have tried Cutting with the 401 as a Lathe Drive (As was my Original Intention) Oh well, we live and learn te he!

http://lathetrolls.com/viewtopic.php?f=1&t=6381&p=41102&hilit=technics+cosmetics#p41102
Regards
Soulbear

[Ritter]

How fascinating, I found the Garrard 401, which shares the 301's Motor to be well "Under-Nourished" in the very subjective, non-objective "Stalling the Platter with a Finger" Test

Well, that is interesting; it is my understanding that the 401 has a slightly improved motor over the 301. I recently serviced mine, and gave it a good half-hour warm up first. That said, the testing I was doing was not at the outer edge, but towards the middle of the platter and of course I was just happy to have cut something, not really being very scientific about it yet.

I had considered the SP10, but there are not many of them down here in the south pacific. So unfortunately trades are out...

[Ritter]

It's been a while since the last update. Life goes on and hobbies get pushed to the back of the queue behind house renovations

Anyway, it quickly became clear that the 301 really wasn't up to the embossing task (Soulbear, you were completely right ). So, I set about making something that would be more powerful. I found an old treadmill and stripped the motor from that... plenty of torque, but only at higher speeds (upwards of 5000 RPM). Gearing it down proved to be difficult, since I would have needed 3 large pulleys, and they seemed to be hard to get hold of. Making them proved to be equally difficult, and a time consuming task. Not to mention the serious amount of movement in the whole thing. Here an image of one of the pulleys I built from MDF.

2017-08-06 12.10.51-1.jpg

I then tried to re-use an old platter with a geared motor from RS. This worked well, but was very noisy. The motor felt like it was a bit beyond it's capabilities and the thin belt driving it didn't give me much confidence either.

2017-10-13 10.43.58.jpg

So, in the end I bought an old Rekokut LP-743. It's easy enough to convert these to 240V by adding a toroidal transformer, and getting a new pulley (since frequence has gone from 60Hz to 50Hz). The LP-743 has a nice flat platter, and it's got good torque, so we're all set now. Thanks Gus for your tips in this space.

2017-11-14 15.28.49.jpg

The moral of this story is: don't spend 6 months trying to avoid the obvious.

[Ritter]

Well, now that I had a decent platter and torque, I decided it was time to rebuild the overhead to be as sturdy as possible. In this process I discovered 4040 extruded aluminium profile, and a local supplier, so that made life easy. The new overhead is now built mostly from 4040 extrusion, with a few parts in wood. I also managed to get a nice pull dashpot that drops the head slowly.

2018-01-09 13.12.07.jpg

Next on the list was a new control "box" for the lathe. I had an arduino fully set up with a DRV8825 module for controlling the stepper, however I tried to switch to a Chinese clone TMC2130 as these offer much nicer stepping. Unfortunately these units were "hard-wired" for some other mode, and I wrecked two units trying to convert them. In the end, I went back to the DRV8825, and added a number of controls: start/stop, 33/45, head position (using a pot), variable spacing (using a pot) and lead-in/normal.

2018-01-12 21.08.46.jpg

Some test runs using the variable spacing controls.

2017-12-27 14.47.59.jpg

Now that the lathe was up and running again after a downtime of almost an entire year, I did some test embossing runs using a cone provided by jjwharris. This gave me excellent results, so that was really pleasing! Good clear signal and not too much background noise. Of course, now I was keen to try cutting. The good folk at myshank were more than happy to help with a long shank for my old RCA head.

More soon.

[Ritter]

We finally got a 3d printer.. man these things are handy for prototyping parts! Anyway, the last two days have been about getting suction designed and built. I spent some time designing a mount for the suction tube... I think revision 8 was the final version. Here a sampling of some of the revisions, and the final in place on the lathe.

2018-01-22 10.47.33.jpg

2018-01-22 18.00.37.jpg

With the suction tube attached, I managed to cut some music into a blank, with the swarf going nicely into the vacuum tube. The vacuum tube is currently connected to an old home vacuum via a 10mm hose and a weird "adaptor" built using cellotape. The home made anti-static spray seems to be doing the job too, so really pleased about that.

The final seems to have well formed grooves that tracked nicely in our two record players... however they look a bit "small" to me; so will compare these grooves to a real record, and see what, if anything, should be changed.

2018-01-22 18.01.16.jpg

The only problem seemed to be a bit of jumpiness in the head towards the end of the blank... not sure yet what was causing that. It certainly wasn't swarf, since this was all being sucked up. Thoughts anyone?

Well, now that I've got that all working, it's time to start on the stereo head.

[jjwharris]

Looking and sounding good!

I need to get started on my turntable...and overhead.

Looking forward to seeing what you come up in regards to the stereo head.

Let me know if you need any ali extrusion!

[jjwharris]

Do you have any close ups of how you are attaching your cutting head?

I'm using a couple of bearings on mine and the wobble is a bit too much..

[Ritter]

Do you have any close ups of how you are attaching your cutting head?

I'm using a small 4040 corner bracket, with a 2020 pivot joint. I've replaced the M5 bolt/nut with an M4 bolt and butterfly nut so that the angle can be adjusted.

2018-01-28 10.20.30.jpg

[tragwag]

for the jumpiness of the head, you'll want to search for a dashpot
some folks have made new ones, I think they'll called Air pots, or something?
But the originals are oil filled, for dampening sudden vibrations to the cutting head.

[stoneley]

This build is great and looking to make something similar myself, so thanks for sharing all your info. Could I ask a couple of questions please, where did you source your dashpot and have you any details on the wiring of the control panel for the arduino

[Ritter]

Hi Stoneley,

Sorry for the delay; been out of town for some time. Anyway, in answer to your questions:

1. The dashpot came from airpot.com. They will sell you a dashpot, but they also offer free samples.

2. The arduino: it's a fairly simple build using a DRV8825 library (from github), and the wiring is just a series of switches that control the software. You can find more on wiring switches to the arduino on the net. For example: https://electrosome.com/switch-arduino-uno/

Cheers

[Ritter]

for the jumpiness of the head, you'll want to search for a dashpot
some folks have made new ones, I think they'll called Air pots, or something?
But the originals are oil filled, for dampening sudden vibrations to the cutting head.

Yeah, thanks for the suggestions. I have an airpot attached to the head. However, it's a "pull" down only, so no protection from upwards motion. I'll need to fit a "push-pull" type to provide that protection.

I think I'll also need to reconsider how I fastened the suction tube to the overhead, since it seems to be providing "drag", possibly causing the jumpiness

[soeffingodly]

This is absolutely amazing so far. Well done. Keep at it, I'll keep reading!

[Ritter]

This is absolutely amazing so far. Well done. Keep at it, I'll keep reading!

Thank you, I really appreciate the feedback!

I've recently rewired the controller to use a A4988 instead of the DRV8825, since that has serious accuracy issues. Not sure if I've posted it before, but this guy did some accuracy tests that show how DRV8825 is skipping parts of steps in 1/16 mode:

https://hackaday.com/2016/08/29/how-accurate-is-microstepping-really/

I'm also reworking the overhead so that the suction doesn't affect the balance of the cutter. I'll post more updates soon.

[basplin]

This is incredible! Would love to know how this is coming along...