A Very Basic Record Lathe

[ilovedrums247]

Hello, I have been working on this lathe for about a year. Starting with a drawing and eventually onto cutting metal and soldering cables.

This week it all came together and i've just started cutting/embossing.

I've got the counter weight set to about ~80g-100g and have been toying with different springs for the cutter depth.

The needle is from Wilson Logan and set to about 7 degrees. I also experimented w a 15 degree rake but it made no difference.

I've got a heat lamp warming up the blank to about 30 degrees.

The 10" blank is from myshank and it does have a slight wobble but it's being held very securely to the platter.

The problem i'm having is that the cuts seems to be too deep, but when i adjust the depth spring i'm unable to find a spot where it'll cut a nice looking groove but also doesn't skip at some point in the rotation. The picture above is from the last cut i made magnified x150

As it stands, everything that's been cut sounds terrible.

Any ideas/solutions from fellow trolls would be greatly appreciated.

[ilovedrums247]

Also using myshanks antistatic wax

[Crismgc]

Do you have an audio sample? Maybe is something about the speaker’s cones, some piece not attached well. With an audio sample maybe I can notice what it should be.

[Crismgc]

The weight of the turntable needle is a factor too

[boogievan]

Awesome build, ...247.

How wide is the groove, across the top, when it looks 'too deep'? (Does it look much wider than most groove-turns on known-playable 'embossed' cuts when viewed on your platter when using the same mic / objective?)

Is there any swarf-suction nozzle? (swarf strings visible on workpiece...)

The counter spring looks kinda 'sprung' and is attached at an angle. Normally, this is vertical. It can be behind or in front of the cutting head.

Is there a silicone fluid-filled dash-pot in that lift-drop box to dampen the oscillations of the counter-sprung pivot? If so, what's the viscocity? ...like, how many CentiStokes is its 'weight''?


- Tim E.

[chris-zwarg]

The grooves in the microscopic picture look terrible. Not sure whether you are trying to emboss or actually cut, but what is happening is that you are just scratching the surface. Unmodulated grooves must look mirror-like and smooth, without any of the small "fuzzy" structures seen in the image. Look at an unworn factory-pressed disc (preferably some classical music that tends to have extended passages at low volume, or use the silent grooves between tracks) to get an idea how it should look like. When the cutter touches the surface there must be no audible mechanical noise at all. If you hear any hissing, squealing, or screeching while cutting silent grooves, something is VERY wrong. Maybe the stylus tip is rough/broken, the angle is very wrong (it can e.g. happen when trying emboss at a "raking" rather than "trailing" angle, with the tip going against the movement of the disc), the weight is much too high, or the material unsuitable for embossing (Polystyrene or PVC rather than polycarbonate). To get a smooth groove without any of this scratching and screeching is maybe the most delicate and complicated aspect of constructing a lathe. Great precision is needed, as a stylus being off the sweet spot in terms of angle, but also position on the disc surface (in front of or behind, rather than bang-on the tangential line from the center spindle outwards), by a very small amount can already ruin the cut, especially on hard materials like Polycarbonate or PVC. Lacquers and wax are much more forgiving, which is probably one reason they were always the preferred materials for pro-grade cuts.

[ilovedrums247]

Awesome build, ...247.

How wide is the groove, across the top, when it looks 'too deep'? (Does it look much wider than most groove-turns on known-playable 'embossed' cuts when viewed on your platter when using the same mic / objective?)

Is there any swarf-suction nozzle? (swarf strings visible on workpiece...)

The counter spring looks kinda 'sprung' and is attached at an angle. Normally, this is vertical. It can be behind or in front of the cutting head.

Is there a silicone fluid-filled dash-pot in that lift-drop box to dampen the oscillations of the counter-sprung pivot? If so, what's the viscocity? ...like, how many CentiStokes is its 'weight''?


- Tim E.

Hi Tim,

Thank you.

The lathe has come along a little further since the first post, although the last couple months i've been lacking the time and energy to experiment (see: 9 m/o & 2 y/o).

The grooves have now gotten much closer to a 'normal' width, but in order for that to happen tho i needed to do two things.

-back off the cutterhead weight (now ~20-30g)
-build a lapidary to make needles

The picture from the first post was taken at an incorrect angle and also the grooves were WAY to deep (goodbye playback needle).

I haven't been able to cut swarf yet, so it's only embossing with metal needles. I also ordered some [0.6 x 0.6 x 3mm] CVD diamonds and have been slowly polishing them but need more diamond coated discs to do so. Hopefully they'll last longer/stay sharper then the steel ones. I've built a swarf catcher but don't have a side blower yet...That's all for "Phase 2"

One big problem i'm having is cutting music loud enough, with grooves deep enough, that doesn't skip on playback. It has seriously made me consider also building a mono head and simplify it all a little more.

The counter spring has been totally changed and now hangs ~75º.

The dash pot is filled with "Team Corally differentieel olie 60ml - 5000CPS", but have considered going thicker and experimenting with different size cans. I've found some small aluminum 'pill/ear plug' containers that are very inexpensive and have rubber seals.

I'll upload pictures soon.

[ilovedrums247]

Do you have an audio sample? Maybe is something about the speaker’s cones, some piece not attached well. With an audio sample maybe I can notice what it should be.

Not yet, but when i get something i'm happy with i will upload it with some pictures and more info.

[ilovedrums247]

The grooves in the microscopic picture look terrible. Not sure whether you are trying to emboss or actually cut, but what is happening is that you are just scratching the surface. Unmodulated grooves must look mirror-like and smooth, without any of the small "fuzzy" structures seen in the image. Look at an unworn factory-pressed disc (preferably some classical music that tends to have extended passages at low volume, or use the silent grooves between tracks) to get an idea how it should look like. When the cutter touches the surface there must be no audible mechanical noise at all. If you hear any hissing, squealing, or screeching while cutting silent grooves, something is VERY wrong. Maybe the stylus tip is rough/broken, the angle is very wrong (it can e.g. happen when trying emboss at a "raking" rather than "trailing" angle, with the tip going against the movement of the disc), the weight is much too high, or the material unsuitable for embossing (Polystyrene or PVC rather than polycarbonate). To get a smooth groove without any of this scratching and screeching is maybe the most delicate and complicated aspect of constructing a lathe. Great precision is needed, as a stylus being off the sweet spot in terms of angle, but also position on the disc surface (in front of or behind, rather than bang-on the tangential line from the center spindle outwards), by a very small amount can already ruin the cut, especially on hard materials like Polycarbonate or PVC. Lacquers and wax are much more forgiving, which is probably one reason they were always the preferred materials for pro-grade cuts.

Hi Chris,

Yes, they did not sound good either, but thankfully much has improved. It's currently cutting silent unmodulated grooves. I'll upload pix soon.