PDA

View Full Version : Gear cutter question



rockrat
07-03-2006, 08:36 PM
Ok, I got a question on finding gear information. After making a few gears for others, I now have the need to make a gear for my lathe. I can gain a few strange instrument type pitches by making a gear or two for my large Southbend. The way I see it, I can spend $40 for a gear cutter and make a few different gears or I can spend $20 - $30 per gear and only have the gears. Greed!

So, I have been reading my little book on gear cutting and it tells me that finding the diametrial pitch can be done by adding 2 to the number of teeth on the gear and dividing by the outside diameter. This has worked so far.

But today, I check the outside diameter of the gear at 2.197 (ish) and 30 teeth. So (30+2)/2.197=14.5 DP. I can juggle the 2.197 around and assume that it is really 2.2 but that only changes things aout about the 2nd decimal place.

So, is this a special order cutter for this here gear? MSC and McMaster list some standard stuff but nothing in 1/2 dp's.

So what say you all.

Thanks rock-

John Stevenson
07-03-2006, 08:40 PM
Check a few more and take an average.
problem is because change wheels don't have fixed centres you can get away with anything.

Chances are they are 14 DP and 14-1/2 PA

.

CCWKen
07-03-2006, 09:23 PM
Or... post a pick and bore. I'll check to see if I have one.

Timleech
07-04-2006, 06:18 AM
14.5 DP is near as dammit 1.75 Mod, which does exist. Unlikely on an American lathe, I suppose?

Tim

rockrat
07-04-2006, 10:09 AM
14.5 DP is near as dammit 1.75 Mod, which does exist. Unlikely on an American lathe, I suppose?

Tim

Well this is a South Bend Toronado. I was told by LeBlond that this series of lathe was mostly built in Spain and then shipped to the US for the final touches like grinding the ways and wiring. So, it may be metric.

I am in need of a 35 tooth gear with a......

Ok now I see. Just took a measurement. I need a 35 tooth gear 16mm tooth width & a 22mm bore. Damn, didnt even think about the metric thing. Live and learn.

So, back to the calculator and books to find a sutible cutter. Thanks for the info guys.

rock-

snowman
07-04-2006, 10:43 AM
yup...make the gears.

14 pitch gears are not available.

i've got a quick change i'm about to part out, old leblond regal, but not for a while...as i want to try to offer the lathe up in whole condition before i part it out. plus i have to wait and make sure my new lathe purchase goes through.

John Stevenson
07-04-2006, 11:37 AM
Well this is a South Bend Toronado. I was told by LeBlond that this series of lathe was mostly built in Spain and then shipped to the US for the final touches like grinding the ways and wiring. So, it may be metric.

I am in need of a 35 tooth gear with a......

Ok now I see. Just took a measurement. I need a 35 tooth gear 16mm tooth width & a 22mm bore. Damn, didnt even think about the metric thing. Live and learn.

So, back to the calculator and books to find a sutible cutter. Thanks for the info guys.

rock-
http://www.hpcgears.com

1.75 mod, 35 tooth 18mm wide 15mm bore £11.99 in my book
but not sure if it's the latest.


[Edit]
http://www.hpcgears.com/newpdf/spurgears_pdfs/spurgears_1.75mod.pdf

Current prices.

.