Gear cutting

[Herbertkabi]

hi crafters and philomaths,

I need some 48 DP spur gears, ca 90 tooths,
Pinions I already have - PA 20°,
Very hard to get these spurs from aluminium (or stypidly expensive),
thats because tried to find Gear Cutter and DIY ,
the only cutter I found and bought is No2, 48DP, PA 14 1/2°,
I will use Aluminium for Spurs, pinion is plastic.

Question:

Will I have big problem when 90 tooth spur has PA 14 1/2° when 20 tooth pinion has PA 20° ???

Cheers,
Herbert

[JLSD]

Hi,
I don't know if it will help, UK supplier lists gears 20deg. P.A.
hpcgears.com.
Price for 90t approx 20 GBP.
Website has full catalogue with prices.
John.

[RICHARD ZASTROW]

Herbert, A 20 deg.PA should not be run against a 14 1/2 deg. PA. That may work for a short time on gears made of soft material, but will wear rapidly.

Involute gears "roll" against each other. Different pressure angles running against each other will interfere and "rub" causing wear.

A 20 deg PA gear tooth is thicker than a 14 1/2 deg. PA tooth and will not fit well in the tooth space of the 14 1/2 deg. gear.

Dick Z

[RotarySMP]

Hello Herbert,

Have you looked at the gear selection of Maedler.de? The metric Module gears are PA 20°. They don't have aluminium, but the do have plastic 90 tooth gears.

[Herbertkabi]

Yeah guys, many thanks for reply.
Pinions I have are very specifics, made especially to fit with ´something´,
thats because I need the spur what fits exact.
Plastic spurs I did think about ... but rather no, it will louse up my design.
Spurs I need ... lets speak about 50 ... 100 pieces, means that when to buy per 20£ then I have to gnaw moss instead of to get some profit after hard work
Also sent few emails to gearcutter companies advertises custom gears - no reply,

Why they making those differend angles at all, why not just one

Seems the only way is to find 48DP No2 20 degree gear cutter,
Spent already two days and cant find ...


regards,
herbert

[RotarySMP]

You could rough grind one to fit your fly cutter by hand, and then finish grinding it to shape on your CNC.

[Herbertkabi]

Yeah, some humdinger machinist can do what ever,
not me with my modest knowledge about.

Thanks to ´Finegrain´ from PM forum at last I found needed cutter for $ 56.27 and already ordered,
48 D/P #2 E188 20º INV. HSS GEARCUTTER TTC PROD
Product: 10-289-482

Im not a grudging guy - perhaps someone else will need this address
http://www.travers.com

Cheers,
Herbert