lead in groove

[fredbissnette]

now that there are literally 100s of lathe cutters doing work now my biggest hurdle on my diy machine is a lead in groove

can you make a consistent lead in groove on embossed records?

[Jccc]

i do lead in grooves on embossed records.
Its really easy to do on a Presto 6N.
when you start cutting you slowly turn the crank thats connected to the feedscrew which causes the spacing to widen.

I am sure you can do it with your machine as well if you figured out how to install a crank on your lathe.

[fredbissnette]

im thinking a variac on the motor (its a geared ac disc ball motor) to control the speed would work??

[markrob]

Hi,

If its a DC motor, you don't want a Variac. That adjusts AC. A variable voltage DC power supply might work, but depending on what voltage and cutting LPI you are currently running you motor at relative to its full speed rating, you may not have enough headroom available to get the carriage moving as fast as it needs to be. You would like the lead-in to be in the 16-32 LPI range (according to the an RIAA standard I have here). If you are cutting at 160 LPI, then you need about a 5:1 speed ratio. For most DC motor's, the speed is approximately proportional to the applied voltage. So if you run with 12V on the motor at cutting, then as a first approximation, you would need to apply 60V to get the speed up to the required level. In practice, you will probably need more drive voltage to compensate for mechanical loading. Running a motor overdriven by that amount might not be good for its health, but in a DIY application, you might be able to get away with it, since it only needs to run at the speed for a few seconds.

Mark

[fredbissnette]

I think your right, I'm gonna switch from a ac geared motor to dc and use a pwm with a momentary switch to hit it with full speed for the lead In.