Change Gears for Hardinge HLV-EM

[glixons]

I just purchased a Hardinge HLV-EM and am interested in understanding change gears. During a recent trip to used tooling dealers, I purchased an English Banjo and two (different) Metric Banjos. Does anyone have a picture of the correct Metric Banjo for the HLV-EM?

Also, I have a pile of gears to go along with the Banjos. They are 3/8" thick with a 5/8" hole. In previous threads for other Hardinge lathes (not the HLV-EM), I see references for change gears have a pressure angle of 14 1/2 degrees and a 20 pitch (whatever these specs mean). Are these spec correct for the HLV-EM? If so, are the Boston Gear, GAxx series, correct for the HLV-EM?

Thanks,
Scott
(703)403-5364

[SGW]

Get thyself a copy of Ivan Law's book "Gears and Gear Cutting" for an excellent introduction to the theory and practice of gears.

Briefly, 14 1/2 degrees is the pressure angle of the teeth. It refers to the angle of contact between the teeth of mating gears.

20 dp is the diametral ptich, which determines the size of the teeth. A 20 dp gear with a pitch circle 1" in diameter will have 20 teeth.

[gwilson]

I don't know about the HLV-EM,,but my HLVH has 20 degree pressure angle gears.

[Rich Carlstedt]

I thought Hardinge used 22 pitch gears ?
Normally available gears from Boston or others are 20 or 24 Pitch

This use of non-standard gears or threads is typical of many manufactures, they want to keep the spare parts business to themselves. Sometimes it is just selfishness ($) and sometimes it is really for quality. I suspect it is the latter in Hardinge's case, as they want to make sure their precision quality reputation stays intact.

But the real answer here is "don't worry about it".
Hardinge has an internal gear box, but when you use the banjo's you are outside the gearbox and therefore as long as all the gears 'there" are the same pitch and pressure angle, it does not matter. That means if you have some Hardinge "external" gears engaging with the Banjo, swap them out with what ever you want to use.