Notes on drawing to specify spur gear

[alexit]

Hi all, I order gears and (only) specify:
No. tooth
Dia Pitch
Pressure Angle
Face width
Ball Diameter
Outer Diameter
Diameter over balls

I get pure junk, involute profile is good on 1/2 of tooth, like arc tangent to addendum circle and dedendum circle on other 1/2. Any two even from same lot won't mesh. Since I didn't specify on drawings Max Runout or TCE, they send garbage and want money. Is learning experience for both (I learn to add notes on drawings, they learn I only pay for parts that mesh together.)

So I ask, what notes are required on drawings to get gears that mesh?

I am looking online and find lists like:
NUMBER OF TEETH xx
STD. DIAMETRAL PITCH/MODULE xx.xxx
STD. PRESSURE ANGLE xx.xx°
HELIX ANGLE xx.xx°
OPERATING CENTER DISTANCE xx.xxx
FACE WIDTH xx.xxx
STD. TOOTH THICKNESS xx.xxx

CIRCULAR PITCH xx.xxx
PITCH DIAMETER xx.xxx
BASE DIAMETER xx.xxx
THEORETICAL OD xx.xxx
ROOT DIAMETER xx.xxx
MIN. ROOT FILLET xx.xxx
ADDENDUM xx.xxx
DEDENDUM xx.xxx
WORKING DEPTH xx.xxx
WHOLE DEPTH xx.xxx

NORMAL BACKLASH xx.xxx
OPERATING BACKLASH xx.xxx
PITCH RUNOUT .xxx
TOTAL COMPOSITE ERROR .xxx
TOOTH SURFACE FINISH (RA) xx
QUALITY CLASS (AGMA/ISO) xx

Is this enough?

Thanks for your help!

 

[diamondjim]

Alexit,
You might want to specify an agma
quality level and TCE value that
you need. You need to specify
also the SAP or TIF diameter that
you need or else specify the mating
part that meshes with this gear.
You need a dimensional spread on
the dimension over pins or balls
in lieu of spread on tooth thickness.

No. of Gear Teeth
Diametral Pitch
Pressure Angle
Face width
Addendum
Dedendum
Tooth thickness Min and Max.
AGMA Quality TCE

To Mate with Mating Part (30 tooth pinion)
Addendum
Dedendum
Tooth thickness Min and Max.
AGMA Quality TCE

 

[israelkk]

This is how I ususally specify a fine pitch gear

Parameters Millimeters Inches
-----------------------------------------------------------------------------------------------
AGMA QUALITY/CLASS No. (2000-A88) Q10C Q10C
Number of teeth 27 27
Diametral pitch (1/inch) 72 72
Pressure angle (deg) 20° 20°
Standard Pitch Diameter (ref) 9.525 0.3750
Actual Pitch Diameter (ref) 9.737 0.3833
Max Testing Radius 4.848 0.1909
Min Testing Radius 4.819 0.1897
Total Composite Tolerance 0.020 0.0008
Tooth to Tooth Composite Tolerance 0.013 0.0005
Outside diameter 10.402 0.4095
Outside diameter tolerance - 0.076 - 0.0030
Max root diameter 8.748 0.3444
Tooth Correction (ref) 0.3 0.3
Measurement pin diameter 0.677 0.0267
Max measurement over two pins (ref) 10.719 0.4220
Min measurement over two pins (ref) 10.675 0.4203

 

[scarecrow55]

Any gear manufacture worth his salts wouldn't send garbage. They would ask questions and help you specify what you required. I'd change suppliers

 

[alexit]

Diamondjim,
What is this SAP or TIF?

Israelkk,
Thank you! Your actual pitch diameter is then 1/2 of operating center?

Scarecrow55,
Was too rush job, quality got bypassed.

 

[Carburize]

"Scarecrow55,
Was too rush job, quality got bypassed."

It never ceases to amaze me how we never have time up-front to get the quality we need but somehow find time at the end to fix it!

 

[diamondjim]

Alexit,
The start of active profile (SAP) diameter is
also referred to as lowest point of single tooth
contact. True Involute Form Diameter is the lowest
point on the gear that still has a true involute
form on it. If your TIF diameter is less than the
SAP diameter you do not involute interference at
the bottom of the teeth. Are your teeth generated
by a hob or shaper or simply laser cut?

 

[alexit]

Gears were supposed to be hobbed, look like made with hand file and pliers. We change to MIM process for new production. THanks for all help.