We are three students currently working on building a lathe for a science fair project. We have the cutter head moving along a gear belt from the outside of a cd to the inside. The gear belt moves slow but we think it should probably be moving slower. Since this is the case, we’ve increased the speed of our turn table while embossing. Should we be doing this?
Also, before embossing the cd, we heat it up with a hairdryer on the hottest setting. Our needle (sewing needle) is creating grooves and vibrates in the cutter head when noise is played through the speakers, however, when we play back the cd, we only get static. We’ve tried experimenting with different counterweights to alter the pressure of the needle. We also have the base turned down and the treble turned up (to account for the RIAA curve). All this said, we aren’t sure what our next steps should be. We would really appreciate any suggestions!
Attached bellow are images of our cutter head and general set up.
PLEASE HELP! Students new to lathes
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PLEASE HELP! Students new to lathes
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pentlandsound
- Posts: 69
- Joined: Mon May 16, 2011 11:25 am
- Location: Edinburgh, Scotland
Re: PLEASE HELP! Students new to lathes
Hi,
First of all, welcome to the Lathe Trolls site, and well done with your project to date. From the pictures it looks as though you've made a really good start on this. I hope I can make a few suggestions / hints that may be of use to you.
If the turntable in the first picture is the one you're using to make the embossing, it may not have enough torque (informally, rotational power) to handle the extra downward force required to emboss a playable track into the CD. A playback deck is designed for a stylus tracking force of up to about 7 grams; if you're using a sewing needle to impress the groove, you may need a down-force of anything between 35 and 100 grams. Most domestic record players may struggle with this, slowing down or even stopping. I've heard good things about certain DJ decks such as the Technics 1210, and models by Stanton; could you borrow something like this for the duration of your project?
For embossing on CD, use the highest speed you can. At least 45 rpm would be good. The reason is that sound waves need a certain amount of 'real estate' - linear space on the record - in order to be recorded and tracked properly on playback. Record companies tend to organise the tracks on LPs so that the most dynamic tracks are near the edge, where the groove is travelling at its fastest, and the more quiet and subdued numbers are nearer the label. As a CD is small, its surface travels slowly under the recording stylus, so try to use the highest rotational speed.
The other main point has to do with the construction of the recording head. The stylus should be mounted in a holder that connects firmly to the inside of the rear of the head. This holder (solid or tubular), the "torque tube", has (at least) two functions: it ensures that the stylus is kept vertical with respect to the disc when it is moved by the drivers, and does not rotate; it also prevents the stylus being pulled forward of the centre of the cones (or even pulled off completely) due to the friction between the stylus and the blank disc. From your second picture, the torque tube should be connected to the raised semicircular tab; it looks as if it is missing.
The construction of the head needs to be as 'stiff' as you can make it. From the second picture, the stylus seems to be held in place by tape or glue, which is likely to be causing problems. A torque tube / stylus holder should help with this, the apexes of the two cones connecting to the tube at 90° respective to each other. The stylus would pass through the tube close to the cones, perhaps at a slight trailing angle, and be held in place firmly - either glued permanently or by means of a setscrew in a tapped hole.
The sewing needle in its unaltered form may be too sharp. If you're getting lots of noise and little else, you may actually be cutting into the CD instead of merely embossing. Steel gramophone needles are still available, are fairly cheap and can be used for embossing. For what it's worth, I used a Dremel, a protractor and a jeweller's magnifier to give the gramophone needle a conical point of approximately 85°. it met the blank disc with a trailing angle of 30° off vertical, and the down-force was about 100 grams.
My first thoughts. Hope some of this is of use! Good luck with the project - making records is quite the rabbit hole once you get started.
David
First of all, welcome to the Lathe Trolls site, and well done with your project to date. From the pictures it looks as though you've made a really good start on this. I hope I can make a few suggestions / hints that may be of use to you.
If the turntable in the first picture is the one you're using to make the embossing, it may not have enough torque (informally, rotational power) to handle the extra downward force required to emboss a playable track into the CD. A playback deck is designed for a stylus tracking force of up to about 7 grams; if you're using a sewing needle to impress the groove, you may need a down-force of anything between 35 and 100 grams. Most domestic record players may struggle with this, slowing down or even stopping. I've heard good things about certain DJ decks such as the Technics 1210, and models by Stanton; could you borrow something like this for the duration of your project?
For embossing on CD, use the highest speed you can. At least 45 rpm would be good. The reason is that sound waves need a certain amount of 'real estate' - linear space on the record - in order to be recorded and tracked properly on playback. Record companies tend to organise the tracks on LPs so that the most dynamic tracks are near the edge, where the groove is travelling at its fastest, and the more quiet and subdued numbers are nearer the label. As a CD is small, its surface travels slowly under the recording stylus, so try to use the highest rotational speed.
The other main point has to do with the construction of the recording head. The stylus should be mounted in a holder that connects firmly to the inside of the rear of the head. This holder (solid or tubular), the "torque tube", has (at least) two functions: it ensures that the stylus is kept vertical with respect to the disc when it is moved by the drivers, and does not rotate; it also prevents the stylus being pulled forward of the centre of the cones (or even pulled off completely) due to the friction between the stylus and the blank disc. From your second picture, the torque tube should be connected to the raised semicircular tab; it looks as if it is missing.
The construction of the head needs to be as 'stiff' as you can make it. From the second picture, the stylus seems to be held in place by tape or glue, which is likely to be causing problems. A torque tube / stylus holder should help with this, the apexes of the two cones connecting to the tube at 90° respective to each other. The stylus would pass through the tube close to the cones, perhaps at a slight trailing angle, and be held in place firmly - either glued permanently or by means of a setscrew in a tapped hole.
The sewing needle in its unaltered form may be too sharp. If you're getting lots of noise and little else, you may actually be cutting into the CD instead of merely embossing. Steel gramophone needles are still available, are fairly cheap and can be used for embossing. For what it's worth, I used a Dremel, a protractor and a jeweller's magnifier to give the gramophone needle a conical point of approximately 85°. it met the blank disc with a trailing angle of 30° off vertical, and the down-force was about 100 grams.
My first thoughts. Hope some of this is of use! Good luck with the project - making records is quite the rabbit hole once you get started.
David
Re: PLEASE HELP! Students new to lathes
Thank you so so much! Your suggestions are so helpful. We really really appreciate you helping us out. We were unable to find a dj turn table but we’ve come up with another solution! We’re going to use a pottery wheel because they can withstand a lot of pressure and spin very fast (we can also control the speed if need be). Additionally, we’re going to redesign the cutter head thanks to your suggestions! We’ll attach pictures soon 
. Thanks again!!
. Thanks again!!