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HLVH speed lever conspiracy theory?

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
The speed lever lie has always bothered me. Swing to the left and I have 0 to 1000 rpm. Ok, adjust to say 700 rpm.
Now swing lever to the right and adjust the speed to 700 rpm by the rpm gauge. The speed is always noticeably faster and not by a little amount.
The speed gauge is the strip of metal that moves up and down next to a metal plate with numbers on it. I say the numbers are a lie.

I recall the right and left names originated from the French chambers of government.
 
I bought a very nice digital laser tachometer on eBay for around $10. It works fine and is, of course, made in China. You need to add a 9V battery and a small scissors to cut the reflective tape.

I have several mechanical tachs, and one even has a digital display, but the rotating shaft input is not as convenient for checking a lathe speed.

Digital Tachometer Non Contact Laser Photo RPM Tach Meter Motor Speed Gauge New | eBay

Larry
 
I bought a very nice digital laser tachometer on eBay for around $10. It works fine and is, of course, made in China. You need to add a 9V battery and a small scissors to cut the reflective tape.

I have several mechanical tachs, and one even has a digital display, but the rotating shaft input is not as convenient for checking a lathe speed.
.

I have the exact same rpm indicator as yours; I have 2 targets, one on the chuck and one on the black hand wheel: they both read the same of course.
Using the "mechanical" indicator on the lathe, won't be as accurate as a digital electronic tach.of course, but it's close enough.
For instance, when I get the silver rod on 470's center, I read 465 on the elec.tach; at 580, I read 606 on the elec.tach; at 770's center , I read 813 on the elec.tach. On the fast scale now, when selecting 2300, I read 2484 on the tach. 1400 ind. was 1405 on the tach., and at 800 indicated, I got 843 on the tach.
It is obvious here, that the rod is only meant as a ball park number. If you want 700 rpm, it makes little difference what scale you use, because you can't read accuracy on that rod.
 
The speed lever lie has always bothered me. Swing to the left and I have 0 to 1000 rpm. Ok, adjust to say 700 rpm.
Now swing lever to the right and adjust the speed to 700 rpm by the rpm gauge. The speed is always noticeably faster and not by a little amount.
The speed gauge is the strip of metal that moves up and down next to a metal plate with numbers on it. I say the numbers are a lie.

I recall the right and left names originated from the French chambers of government.

I would bet maybe a quarter, that the 2 speeds were more nearly correct when the machine was new. With new belts the difference would probably get smaller.
 
I would bet maybe a quarter, that the 2 speeds were more nearly correct when the machine was new. With new belts the difference would probably get smaller.


To be fair, wear on the Reeves drive sheaves at the most commonly used speeds will also affect the linearity of the speed indicator's readout.

Don't most HLV* users adjust the speed and feed to get the desired finish by eye, once the approximate starting point is set, rather than to some exact number, even to the extent of increasing the speed during a facing cut? That's what I do.
 








 
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