Shaper won’t get up to full speed

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Forum topic by DaveNielsen posted 08-02-2019 12:15 AM 354 views 0 times favorited 4 replies Add to Favorites Watch
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4 posts in 89 days

08-02-2019 12:15 AM

Topic tags/keywords: shaper

I have a fairly new Jet shaper. It won’t get up to full speed now, and is incapable of making any cuts. It runs smoothly when it isn’t under load, just at low speed. I have no idea why. My table saw is also 220, and runs fine, so it isn’t an electrical issue. I had the motor replaced last year when it stopped running entirely. Any help would be appreciated.

4 replies so far

View WoodES's profile


152 posts in 2205 days

#1 posted 08-02-2019 05:11 AM

I had a similar problem with my Grizzly jointer, 220v, 3 hp motor. Turns out it was the points for the start capacitor and a bad start capacitor.

After discharging, you can test your capacitors with a volt meter. Perform a google search on capacitor testing for more information.

Here is a link to testing and adjusting the centrifugal

switch. Centrifugal Switch

I replaced the start capacitor, run capacitor, centrifugal switch, and points for about $40 and it runs great. Grizzly tech support was very good with the assistance. Hopefully you’ll have similar luck with Jet as I have a few of those tools too….

View TDSpade's profile


117 posts in 2930 days

#2 posted 08-02-2019 06:32 AM

Make sure that it is properly set up for 220v. Find a wiring diagram for that model and double check. There should actually be a wiring diagram on the inside of the access plate.

Also make sure that the wiring cord didn’t have a wire come loose. Sounds like it’s only running on one leg.

I had the same kind of lack of performance with an old jointer I bought off of craigslist. Fired right up but couldn’t handle a load. It was Wired incorrectly. Rewired it and it ran like a champ.

-- For every expert, there is an equal and opposite expert.

View CaptainKlutz's profile


1900 posts in 2008 days

#3 posted 08-02-2019 07:57 AM

If it used to work ok, then either:
- loose wire
- loose belt
- Centrifugal switch is not activating. Check contacts and adjust.
- Bad run capacitor (since it starts OK)

If it has never run right:
- it’s wired wrong voltage, or
check the list above.

Best Luck

-- I'm an engineer not a woodworker, but I can randomly find useful tools and furniture inside a pile of lumber!

View bigblockyeti's profile


5984 posts in 2235 days

#4 posted 08-02-2019 04:00 PM

That symptom sounds much like running a 240V motor on 120V which will work perfectly fine 99% of the time but be way down on power once a load is applied. If the centrifugal switch isn’t toggling off the start to the run windings, it would pull too much current and get hot pretty quick but should have plenty of power before tripping the breaker or thermal overload. It sounds like you have a bad run capacitor assuming everything works normally while it’s getting up to speed.

-- "Lack of effort will result in failure with amazing predictability" - Me

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