Delta Mortiser Running in Slow Motion

  • Advertise with us

« back to Power Tools, Hardware and Accessories forum

Forum topic by bruc101 posted 09-16-2018 06:30 PM 593 views 0 times favorited 10 replies Add to Favorites Watch
View bruc101's profile


1383 posts in 4319 days

09-16-2018 06:30 PM

I’ve got a Delta Mortiser that I bought several years ago. I’ve not used it in several months due to having a more powerful one.

Yesterday I started to use it, and when I switched it on, it ran in slow motion and kept getting slower. The motor also warmed up more than usual so I switched it off.

Anyone have any suggestions as to why and a fix for it?

I’ve got it set up to run only 3/8” mortises.

Thanks in advance.

-- Bruce Free Plans

10 replies so far

View lumbering_on's profile


578 posts in 1267 days

#1 posted 09-16-2018 06:38 PM

Have you checked the tension on the belts? Or is this a direct drive?

View a1Jim's profile


118066 posts in 4354 days

#2 posted 09-16-2018 06:51 PM

Many times problems like this pops up it involves sawdust clogging things up.


View runswithscissors's profile


3099 posts in 2802 days

#3 posted 09-16-2018 10:48 PM

Could be a start capacitor, maybe?

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

View GR8HUNTER's profile


7577 posts in 1489 days

#4 posted 09-17-2018 02:26 AM

not a start cap from what he describes :<((

maybe motor cant breathe if it got hot :<))

-- Tony---- Reinholds,Pa.------ REMEMBER TO ALWAYS HAVE FUN

View bruc101's profile


1383 posts in 4319 days

#5 posted 09-17-2018 05:20 AM

Thanks guys for your replies. I’m going to open up the motor today and see what I can find. I’ll let you know.

-- Bruce Free Plans

View bruc101's profile


1383 posts in 4319 days

#6 posted 09-17-2018 07:12 PM

I was able to get the fan off the top and blow some air down into the motor. It acted like it wanted to pick up and go and then there will be a little bump and it starts slowing down again. The motor also starts getting hot the longer I let it run.

-- Bruce Free Plans

View DBDesigns's profile


232 posts in 775 days

#7 posted 09-19-2018 07:20 PM

This is a blind guess but it sounds like a bearing or some kind of drag on the motor shaft.

-- I remember when Grateful wasn't Dead

View waho6o9's profile


8909 posts in 3354 days

#8 posted 09-19-2018 07:36 PM

That’s odd.

Technical Support
Product Assembly, User or Other Product-Related Questions


Good luck

View pintodeluxe's profile


6158 posts in 3590 days

#9 posted 09-19-2018 08:31 PM

Clogged or bent mortising bit? Remove bit to rule that out.

Bad Run Capacitor? If yes, replace both capacitors.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View bigblockyeti's profile (online now)


6581 posts in 2498 days

#10 posted 09-19-2018 11:39 PM

I believe those have a single capacitor, check it and replace if bad. I can’t remember if they have a centrifugal switch for the start windings but having that fail would result in slow running and getting hot quickly.

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

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics