Acetal Homopolymer
Also known as Delrin or POM, this is our favorite choice for plastic gears. Acetal naturally has low friction, high wear-resistance, high strength, and high stiffness. Use this material for gears, lightweight bearing surfaces, fixture blocks, and more.
| Overall Sizes |
| Largest Outside Diameter (ODmax) |
2.91 in |
|
| Max Length (L), no bored features |
9.5 in |
Limited by machine clearance. |
| Max Length (L), with bored features |
6.25 in |
Features cut into the face of the part require more room for the tool to move into the part, subtracting from available room in the machine. |
| Minimum Wall Thickness |
0.04 in |
|
| Max L:D ratio with no Tailstock |
4.5 |
If the part is too long compared to its diameter, the cutting forces will push the part away, causing inaccurate dimensions. Allowing for a Tailstock can help exceed this limit. |
| Max L:D ratio with Tailstock |
10 |
Even with a Tailstock supporting the end of the part, cutting forces near the middle of a long part can cause deflection and inaccurate dimensions. |
| Feature Sizes |
| Maximum Radial Step | 0.826 in |
0.119 in minimum groove width |
| 0.629 in |
0.060 in minimum groove width |
| Maximum Boring Depth | 1.790 in |
For hole diameters 0.258 in and larger |
| 1.340 in |
For hole diameters 0.196 in and larger |
| 0.890 in |
For hole diameters 0.133 in and larger |
| Minimum Groove Width | 0.119 in |
0.826 in maximum depth |
| 0.060 in |
0.629 in maximum depth |
| Internal Threads |
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| External Threads |
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| Gears |
| Minimum Number of Teeth |
12 |
Our gears are made by hobbing or single-tooth cutting, both of which have limitations under a tooth count of 12. |
| Maximum Helix Angle, Helical Gears |
45° |
Limited by machine clearance. |
| Available Tooth Sizes | 16 DP hob |
20° pressure angle |
| 24 DP hob |
20° pressure angle |
| 1.5 mod hob |
20° pressure angle |
| 1.25 mod hob |
20° pressure angle |
| 1 mod hob |
20° pressure angle |
| 0.8 mod hob |
20° pressure angle |
| 0.7 mod hob |
20° pressure angle |
| 0.6 mod hob |
20° pressure angle |
| 0.5 mod hob |
20° pressure angle |
| Maximum Gouge |
3 times module |
The maximum allowable distance for the gear cutting tool to enter the part. Features nearby to the gear surface will get gouged if they are too close. |
| Maximum Number of Gears per Part |
4 |
Be aware of gouging when combining gears in one part. See: How to Make Stacked Compound Gears and Herringbone Gears |
| Tolerances |
| Diameter Tolerance |
±0.005 in |
|
| Length Tolerance |
±0.005 in |
|
| Thread Tolerance |
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| Gear Class |
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| Material Properties |
| Not tested or guaranteed. Use appropriate safety factors in design. |
| Density |
1.41 g/cc |
|
| Yield Strength |
66 MPa |
|
| Ultimate Strength |
69 MPa |
|
| Elastic Modulus |
3 GPa |
|
| Hardness |
95SD |
|
