# Plastic Gears in the G0704



## Wheels17 (Mar 9, 2013)

I just bought a G0704 from Grizzly, and I've read a lot of notes that talk about breaking plastic gears in the headstock.  I figured the best way to prevent this was to order a spare with the mill.)  So, I talked to technical support and they had me order part P0704209 GEAR 37T, which appears to be the gear that is driven by the gear on the motor shaft.  It was, and still is, backordered.

I then noticed in a YouTube video, someone was replacing a different plastic gear, the double one that slides to change speeds.  I believe the part number is P0704212, GEAR 42/62T.

So my question to any and all that have broken a gear in a G0704.  Which one did you break?  Part 209 or part 212?


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## Dr.Fiero (Mar 10, 2013)

I haven't made enough chips to break one yet - but I'm pretty sure that if ANYTHING happens up there, I'm doing a belt drive conversion like Hoss'


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## 7.62x39 (Mar 10, 2013)

From what I've read the best way to approach this is to change out the gear box gears with metal ones such as these.
http://littlemachineshop.com/products/product_view.php?ProductID=3449&category=1687114045
But leave the intermediate gear (the one you were referring to) plastic. The reasoning behind this, which makes sense to me, was to leave the plastic one there as sort of a "shear pin" (weakest link in the chain) since that one is cheap and easy to replace. Where as gear box gears changes are a lot more work.
Anyway that's the advise I followed


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## Wizard69 (Mar 13, 2013)

7.62x39 said:


> From what I've read the best way to approach this is to change out the gear box gears with metal ones such as these.
> http://littlemachineshop.com/products/product_view.php?ProductID=3449&category=1687114045
> But leave the intermediate gear (the one you were referring to) plastic. The reasoning behind this, which makes sense to me, was to leave the plastic one there as sort of a "shear pin" (weakest link in the chain) since that one is cheap and easy to replace. Where as gear box gears changes are a lot more work.
> Anyway that's the advise I followed



Tose are for Sieg style machines.   I believe the 704 is fundamentally different.   As to the 704's plastic gears I'm not too sure they have the same failure rate as the Sieg gears.   Most people updating the 704 do so for other reasons.


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## JOSHUAZ2 (Mar 14, 2013)

My 0704 has had the speed control turned up to max and i am not nice to it and i have never hurt the plastic gears. i did clean and grease them when new and set the clearance as tight as possible (it was very loose from the factory).

Roy.


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