Slow speed gear option on 4 post 20” planer

[Bob Cooper]

I have a jet 20” planer that I put a helical head in a few years ago. I still get some tearout whenever the grain goes nutty like near a knot. Really not too different than my straight knife DJ-20.

I know Jet used to sell a reduction gear that would allow you to make the planer feed slower.

Has anyone installed this?
if so did you notice much difference?

[Bruce Wrenn]

I have a jet 20” planer that I put a helical head in a few years ago. I still get some tearout whenever the grain goes nutty like near a knot. Really not too different than my straight knife DJ-20.

I know Jet used to sell a reduction gear that would allow you to make the planer feed slower.

Has anyone installed this?
if so did you notice much difference?


Doesn't your planer already have a two speed gear box?

[Bob Cooper]

Yes but jet sells a different gear and chain as an add on kit to modify both speeds downward

[Alex Zeller]

I think it comes standard on the Powermatic 209 planer. Maybe asking if anyone with one has swapped the gears/ chain out for their opinion.

[Rich Aldrich]

I have a Powermatic 209HH. I changed the sprocket and cha. It made quite a difference on Birdseye maple for eye tear out.

I bought it used but the owner had the high speed sprocket installed. It came with the smaller drive sprocket and shorter chain. I will let you know later today the differences in the parts.

[Bob Cooper]

Thanks Matt

[Rich Aldrich]

Just pulled the cover off the drive. The high speed sprocket is 18 tooth. The chain is 53 pitches (number of spaces between rollers)

The low speed sprocket is 12 tooth. The chain is 50 pitches (number of spaces between rollers.)

I have the 12 tooth on so the low speed is 16 FPM and the high speed is 20 FPM. I think the high speed sprocket is 24 and 31 FPM.

Sorry I didn't get back to you sooner.

[Bob Cooper]

Thanks Rich. If I do the replacement I’ll need to do some comparisons on the same piece of wood to see if I can tell a difference.

[Alex Zeller]

I suspect that the gears/ chain can be installed in most 4 post planers. It would be nice to see real world results to determine if they are worth buying.

[Rich Aldrich]

Mine came with the extra sprocket and chain. Where I notice the difference is birdseye maple when I made the toy box for my grandkids. There no eye tear out. Unfortunately, I didn't think to take pictures of the boards before I changed the sprocket and chain.