Hello All,
I service two lathes that are right next to each other. Lathe 1 and Lathe 2. Recently, Lathe 2 has started having an issue when "dropping" the cutting head and when it cuts a lock-out groove. Sometimes it sounds horrible. It definitely looks horrible. Now, one thing that I observed between the two lathes is the delay of the lead screw from when the cutter head is "dropped" with the lever to when the lead screw starts rotating again.
Lathe 1 starts up again almost instantly. Lathe 2 on the other hand does not. On Lathe 1 it is possible to see the actual initiation of the groove, where the stylus started cutting. On Lathe 2, you cannot. The stylus cuts into its previous groove.
Is there any way to adjust this with a pot on one of the cards? I really hope so!
Here are two videos showing the timing difference between the two lathes.
Lathe 1 - https://drive.google.com/open?id=0B_Mjin07WeVAY25lQTRZalpWbVU
Lathe 2 - https://drive.google.com/open?id=0B_Mjin07WeVAdnE4TjlVamZlVVE
If anyone knows or is able to point me in the right direction that would be greatly appreciated! If you need any further information from me in order to better understand or help me with a solution, please do not hesitate to let me know!
Sincerely,
Thor
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grooveguy
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Re: Initiation of cutting (head down) - Lead screw delay
Hello, Thor; I'm really surprised that no one has got back to you on this yet. It would be nice to see a 'longshot' of your system; I have no idea of what lathe you are talking about. Here is some information from my own experiences, however.
Very often the one-way 'clutch' that drives the leadscrew uses a coil of spring wire wrapped around an unthreaded part of the screw. One end of this spring is connected to a drive gear or pulley, and when the pulley turns in its normal direction, the spring tightens around the screw and drives it. This allows you to turn the screw in this same direction much faster, to spiral between cuts or for a lock groove, for instance. There is always a 'catch-up' time following a manual turning of the leadscrew, for the spring to once again tighten up and provide the slower drive.
Often these springs will get messed-up, usually by someone trying to turn the spiraling crank in the wrong direction. If the spring is not almost tight on the screw to begin with, it takes longer for it to coil-up and tighten. Most of the Rek-O-Kut lathes I've had work this way, and I did have one that did exactly what yours appears to be doing. The fix is to disassemble the clutch mechanism completely and very carefully put coil tension back in the spring. Be cautious and work slowly; your spring wants to look a little smaller than the leadscrew end when your are finished. Place it over the screw and turn in the 'slip' direction to get it back on.
This supposes that we're talking about the same type of clutch mechanism. Again, more information on your lathe would be helpful. Also make sure that there is no end-to-end play in the leadscrew. Usually there's a 'dead center' bearing that can be adjusted to take out any slop.
Very often the one-way 'clutch' that drives the leadscrew uses a coil of spring wire wrapped around an unthreaded part of the screw. One end of this spring is connected to a drive gear or pulley, and when the pulley turns in its normal direction, the spring tightens around the screw and drives it. This allows you to turn the screw in this same direction much faster, to spiral between cuts or for a lock groove, for instance. There is always a 'catch-up' time following a manual turning of the leadscrew, for the spring to once again tighten up and provide the slower drive.
Often these springs will get messed-up, usually by someone trying to turn the spiraling crank in the wrong direction. If the spring is not almost tight on the screw to begin with, it takes longer for it to coil-up and tighten. Most of the Rek-O-Kut lathes I've had work this way, and I did have one that did exactly what yours appears to be doing. The fix is to disassemble the clutch mechanism completely and very carefully put coil tension back in the spring. Be cautious and work slowly; your spring wants to look a little smaller than the leadscrew end when your are finished. Place it over the screw and turn in the 'slip' direction to get it back on.
This supposes that we're talking about the same type of clutch mechanism. Again, more information on your lathe would be helpful. Also make sure that there is no end-to-end play in the leadscrew. Usually there's a 'dead center' bearing that can be adjusted to take out any slop.