2015 POTD Thread Archive

Last night I put the brass tip set screws to use while mounting the new 5C set true chuck. I got the run-out down to 2 tenths, before I got tired of chasing my tail.
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Can't be that difficult, Chev - if the spigot on the backplate's tall enough, all you'd need to do is take a few thou" off the diameter, drill the chuck and tap for the grubscrews, if it's not you might need to take some off the mating face to give the grubscrews somewhere to push as well. Might be worth making up brass tips for the grubscrews so they don't chew up the backplate spigot?

Dave H. (the other one)
 
Not sure it will work, the set true chuck is longer behind the keys than my non set true, but I may be able to grip a gage pin in a collet in the 5c chuck, then grip the other end in my 4jaw and dial it in to .0000 or close, then turn the boss on the back of the 5c chuck, then it would be concentric, I would have to re-turn the mounting adapter to the larger size but it may get rid of all the runout, I don't use the chuck now because of the runout...
 
I'm not sure you'd be able to get it to run true enough with out the set screws. Unless you're turning a taperd interface, getting something to be concentric within a tenth or 2 is really difficult.
 
chevydyl said:
Not sure it will work, the set true chuck is longer behind the keys than my non set true, but I may be able to grip a gage pin in a collet in the 5c chuck, then grip the other end in my 4jaw and dial it in to .0000 or close, then turn the boss on the back of the 5c chuck, then it would be concentric, I would have to re-turn the mounting adapter to the larger size but it may get rid of all the runout, I don't use the chuck now because of the runout...
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You can improve runout that way. I had a 3 jaw chuck with beat up jaws and .025 runout. I turned the shoulder down .010" on the backplate , centered the chuck as good as possible , ground the jaws. I then chucked a 1" OD pice of rill rod in the chuck and chucked that assembly in my 4 jaw on the lathe, indicated the drill rod as close as possible, then turned the recess in the rear of the chuck. Refit to back plate. This is the best chuck I have now.
 
chevydyl said:
I don't use the chuck now because of the runout...
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Chevydyl, why not grind the inside of the chuck when mounted? I had the same runout problem with my Bison D1-4 mount chuck. A 20 minute job with a tool post mounted Dremmel and grindstone and I'm down to a couple tenths.
 
That has crossed my mind numerous times, gotta make a mount for mine...
The other thing I gotta do is make a mount for my Bosch Colt router to mount to my mill head, especially for cnc engraving.
 
RJSakowski said:
LED's (and all other solid state diodes) have a property where the voltage drop across them will decrease with increasing temperature. If some sort of current control is not use, they go into a thermal runaway mode and self destruct. The simplest way of controlling the current is to put a resistance in series. When the current starts to increase, the voltage drop across the resistance increases, reducing the amount of voltage available to the LED.

The strip lighting which is becoming commonplace of late uses this technique. Typically, three LED's are connected in series and in series with the resistor. White LED's have an operating voltage window of about 3.0 to 3.5 volts so three in series gives a nominal voltage of about 10 volts. The resistance drops any remaining voltage. The strips that I have used will operate from about 11 volts to 14 or so with increasing current and brightness as the voltage increases. Somewhere above 14 volts, the LED's are being over driven, shortening their life.

LED's can also be operated on ac current, using their property as a diode rectifier. The now ubiquitous LED Christmas lights will series wire some thirty or so (for 120v.ac) without any additional circuitry.

Another method of driving LED's is using and active driver which contains electronic circuitry to set the drive current. This type of driver can typically operate over a large input voltage range. Some that I have used can have a 25 volt operating swing. Active drivers are also available in a boost configuration, where they increase the output voltage, and for operation on ac power, in which case the module has a built-in rectifier. Many of them also have provision for dimming, either internally or externally.

Bob
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