With so many new people getting into lathe cutting, we wanted to create a quick, concise guide to three essential parts of lathe calibration, no matter what lathe you are using. We won't go into too much detail, various topics are covered in our other blog posts, but for those starting out, here are three key steps you must complete to properly calibrate your setup for cutting.
1: LATHE CALIBRATION
Groove Depth
For cutting plastic, aim for a depth of at least 50 microns (0.05mm) as a starting point. Groove depth is crucial for accurate fidelity, stylus life, and playback quality. If you're unsure how to measure groove depth, we have two blog posts covering this here and here.
Stylus Travel To Centre
Your stylus must cut toward the exact centre of the spindle so your grooves end up perfectly centred on the record. You can check this by using a blank disc and drawing or scoring a centreline with a knife and metal ruler, or you can use the alignment tool we make specifically for this task here.
Vacuum System
Ensure your vacuum system is working properly. If there isn't much suction, you've got a blockage that needs sorting. Using a tiny amount of talc powder occasionally can help eliminate static buildup within the tube. Check the vacuum system regularly and make sure the vacuum tube is positioned correctly, a few millimetres from the stylus and blank is a good starting point.
2: PLAYBACK CALIBRATION
The only volume that matters when cutting is what you're actually putting onto the disc, and the only way to measure this accurately is from your VU level meter. You must calibrate your playback to 0 VU using a professional test record (we use the Ortofon Test Record). When setting your cutting volume, you monitor your cut and take your volume reading from this level meter. 0 VU is a good volume to learn with, later you'll be able to cut much louder. If you're using a level meter that only goes to 0dB at the end of the scale, you should remove these markings and set 0 VU at the end of your yellow LEDs, giving you headroom when cutting louder.
3: CUTTING CALIBRATION
It's advisable to get your cutting chain calibrated so the full system works cohesively and as expected. We use a custom cutterhead EQ (for those wanting to learn how to do this, see here), and due to the large high end boost, often 25dB in the high frequencies, headroom needs accounting for. In our setup, we normalise all audio to -27 LUFS before it hits the EQ. This gives plenty of headroom and means all audio cuts at roughly the same volume. If you're cutting an album, we normalise the first song, then adjust all others by the same dB amount to ensure the audio plays as intended from song to song. Your cutterhead EQ must not clip internally.
These three steps are essential to work through thoroughly when starting out, and doing so will save you a lot of headaches down the line. For those who haven't seen it, see here for 'A Beginners Guide To Lathe Cutting'.