LumberJocks

3HP Motor Tear-Down Clean-up and Bearing Replacement #1: 3HP Motor Tear-Down, Clean-up and Bearing-Replacement

  • Advertise with us
Blog entry by RichmanNot posted 01-25-2017 08:27 AM 877 reads 0 times favorited 7 comments Add to Favorites Watch
no previous part Part 1 of 3HP Motor Tear-Down Clean-up and Bearing Replacement series Part 2: Clean-up Time and Painting Time! »

Well I decided it was the day to get after the motor of my recently purchased “barn-find” Powermatic 66. I ordered new bearings for the motor from Accurate Bearing and they came within a few days of placing the order by email using one of the PDF Order Blanks I found on OWWM.

My 3HP motor is a MARATHON Electric, it is 230v Single Phase. The Bearings for the motor were listed on the motor tag (White Sticker on the motor housing). Having the bearing information before hand saved me from having to tear down the motor to get to the bearings. As the number is stamped on the bearings. Once you do get down to removing the bearings it is a good idea to VERIFY that you did indeed order and receive the correct bearings and that the numbers on the old ones match the number on the new ones. (Or that the bearings are a cross-reference match)

Also you want to be sure and buy a “sealed bearing” UNLESS your motor has bearings that are periodically lubricated (some type of OIL PORT would be on each end of the housing if that were the case).

In my case the motor had these (2) plugs with a straight slot for a screwdriver… I later figured out they were Oil ports that were plugged off.

Most likely you will be replacing SEALED (permanently lubricated) Type bearings.

The Bearing numbers for my Marathon Motor are: 6303 LL NA, and 6305 LL NA. The total for the two motor bearings came to just $8.75 (I also ordered the two Arbor bearings for the saw arbor part number 6304 LL NA – they were $4.90 each) So my total invoice for all 4 bearings with shipping of $7.80 came to $26.35.

The first step was to get the motor onto my work table and do some bit of exterior cleaning. Here is where a shop vac comes in handy, along with some tool to do a little digging and scraping to get the “caked on” sawdust freed up and into the vacuum cleaner.

The next step is to remove the casting that mounts the motor to the saw arbor. (Boy this stuff is HEAVY DUTY!)
But before I started to loosen the 4 bolts, I took this photo to help me later when I need to reinstall the casting
.

Doing some cleanup with the shop vac.

Before you begin to remove the pulley, you need to take a measurement of where it sits in the shaft. I used a pencil and a razor blade to make a record of the depth of where the shaft is in relationship to the top (face) of the pulley. (In my case the end of the shaft is 3/4 of an inch down from the face of the pulley)

I sliced a cut on the pencil then measured where that slice was.

Here it measures right at 3/4 of inch on the pencil scribe ,mark.

The V-Belt Pulley is the next thing to remove. I was glad I used to work on cars and trucks, as I had these gear pullers on hand.

OK before you get all excited, you need to remove the set screw that holds the pulley onto the shaft. The set screw will be lined up with the Keyway Key. There may be several other holes in the pulley, but those are drilled to help balance the pulley (there should only be one set screw and one keyway) But your motor MAY be different?

Oh… by the way, I like to use a little “Kroil” on everything that needs to come apart! This stuff is AMAZING worth it’s wait in gold! A little bit is all you need!

Using an allen wrench (I like these long T-handled ones), Remove the set screw.

Now set up the puller. Having used the Kroil and letting it soak a few minutes, the pulley came off fairly easy.


Here is the removed pulley and the keyway.

Next I sat the motor up onto the cast mounting that I removed earlier so that I can work on the other end.

Using a 1/4 inch wrench (I used this little ratcheting one), remove the screws holding the rear sheet-metal shroud on the rear of the motor housing to expose the rear fan.

Here is the rear fan, again use the shop vac and scrapers to get rid of the caked on sawdust.

The rear fan is also held onto the shaft by a small set screw. With a little help of some Kroil, the fan came off easily just by lifting it up with my hands.

Here is the rear end minus the fan.

Next I decided to investigate the black junction box on the side of the motor (this is where the capacitor and wiring connections are located)

Wow what a lot of saw dust! How did it get in here? More vacuuming and delicate scraping in here (you could use an air hose and blow it out … but be cautious).

The J-box cleaned up pretty well.

On the rear end casting there is also a small cover plate, which is right over the little red reset button (not all motors will have this little red reset button).

I removed the access cover and the paper (or cork?) gasket and you guessed it more saw dust!

Again some more house cleaning required.

Once this area was cleaned up I moved back to the rear end and loosened the (4) long motor housing case bolts. This allowed the rear casting piece to come loose. BUT >>> DO NOT REMOVE IT YET! Just loosen the bolts and leave the (4) long bolts connected WE ARE NOT QUITE READY TO REMOVE REAR END CASTING! WAIT! We will take it off shortly!

NOTE: Good advice offered in the comments by maxhall which I will repeat here: Before you remove that endbell I would put a piece of tape across the piece where it mates and draw a vertical line on the tape so you can easily line it up. Also take copious amounts of pictures and put everything in labeled baggies.

(I used a small plastic jar for the small parts)

SO NOW WE ARE about to get into the “guts” of the motor. The (4) long bolts have been loosened on the back end of the motor BUT NOT COMPLETELY OUT YET.

So now what you need to do is either use a plastic dead-blow hammer or a small block of wood with a hammer to give a few light taps on the END of the shaft protruding out of the BACK casting. Gently “whack” on the end of the shaft and it will “PUSH” the rotor OUT THE FRONT of the housing and force the front end casting to separate and come off of the motor housing.

As you begin to see the separation take place keep a free hand available and as the rotor begins to be exposed, take ahold of the casting allowing it to slide out of the housing keeping it “balanced” to avoid “dragging” on the “WINDINGS”.

Once again you will have some cleanup! It seems that sawdust can get into everything on the motor!

(The shopvac took care of the loose sawdust— later I will describe how I used an air gun to blow out the motor housing and cleaned the “windings” back to “like-new” condition.)

Once the rotor is out it is still connected to the front casting, and the next step is to remove the rotor from the front casting, and then proceed to the task of removing the “front bearing”.

The front casting is held on by those (2) small flat head screws. These flat head screws hold a ring that is located behind the front shaft bearing. Loosen and remove the two screws now.


The front end casting now needs to be “separated” from the the rotor shaft.

As the rotor and front casting are now free, the rear casting will also now be able to be removed BUT WAIT leave the long screws in and let’s get the front end dealt with 1st.

OK… grab that dead blow hammer (or your block of wood and hammer) and tap on the end of the shaft to free the shaft from the front casting .

Yeah, I know I am showing the rear shaft with the hammer – but you get the idea – the front end needs the same gentle “whack job”

Next it is back to choosing the right configuration of puller arms on the gear puller so the front bearing can be removed (pulled) off of the front pulley/rotor shaft.

BUT…. Before we go to that step, let me show you the opposite end first! On the rear end of the rotor shaft where we removed the “rear fan” previously, there is a device on the shaft which it typically called “the starter” (although that is probably a layman’s term and not the correct term). The correct terminology and description is that it is a “Centrifugal Switch”. The device is an electrical switch which operates on the centrifugal force of the spinning rotor shaft and it activates and deactivates the starting winding thus the term starter switch it essentially releases the starting winding once the rotor reaches its normal operating speed.

More information can be found on WikiPedia in case you are curious for more details on this function of this device

For your motor tear-down here it is prudent to just take a look at the device and see if it “LOOKS”OK… No signs of damage or loose parts. The springs should be looked at and anything out of the normal will be pretty obvious.

OK time to get that bearing removed!

Once you have the gear puller in place, grab a heat gun (or your wife’s hair dryer). Put some HEAT to the old bearing! My heat gun can get pretty hot!

(The HF heat gun claims it can get up to 1,112 degrees – and I believe it will)

Just use the low setting and try and heat the bearing uniformly by rotating the rotor as the heat is applied. Once you think it is pretty well heated up, try tightening the gear puller nut. (I was unable to hold the puller against the force of the pressure – so I engaged the puller side between the vice jaws to restrict the twisting effect which allowed me to continue the tightening of the nut.

WARNING! DO NOT BE TEMPTED TO USE THE VICE JAWS ON THE ROTOR OR ROTOR SHAFT! NO, NO, NO!

As the nut on the puller is getting harder to turn, be sure the gear puller stays in place between the vice jaws and the shaft does not touch anything. I was glad to hear that “SNAP” sound—as that is when I knew the bearing had been pulled free! (A little bit of Kroil was used earlier – and seemed to help even though the heat pretty much ended it’s life)

Remember that “RING” well here it is. It sits behind the bearing and essentially holds the front casting on with those two slotted head screws.

NOTE: The front cooling fan remains on the rotor shaft and need not be removed. Likewise the “centrifugal switch” does not need to be removed (unless of course it is damaged or non working). I noticed some spots of rust on the rotor, but I did not do anything to them, the rust was not severe and won’t affect the rotor function.

OK turning now to the rear casting… This is the “business end” of the shaft. The rear casting has the electrical components (the contacts) and in my case it has that small red reset device (again your motor may not have one)

The “contact device” is held to the rear casting by (4) flat head screws seen here. Remove the screws, treat the contact device “gently” it will remain attached to the winding on this end of the motor. Be gentle also with the wiring here!

Once you have removed the “CONTACT DEVICE” held by (4) screws to the rear casting, set the casting down. Looking at the inside of the casting, you will also see a “flat-head screw” that screw is what holds the rear bearing down in a well in the casting shown here…

Grab a flat screwdriver remove the screw and bearing.

Remove the rear bearing (mine was kinda stuck from the grease – so I used a small screwdriver and pushed it out from the back of the casting) The bearing just “lays” in the “well” it is not “pressed in there”.

But, under the rear bearing is what is commonly referred to as a “wavy washer”. It may be hidden under some grease but dig it out…

(make sure it is still wavy and not cracked?)

YEP… Time for more housecleaning. Vacuum the sawdust from the parts BUT be very careful with the contact device! DO NOT TREAT IT ROUGH! Later you will need to “clean” the contacts with some fine emery paper (or a ignition points file)

ALL RIGHT….SUCCESS! We have the motor apart. All that is left to do now is some more cleaning (and in my case a new paint job) and we can move onto reassembly!

So until next time… I will try and post more pictures of the clean-up I did plus my “masking and painting” of the parts, then the re-installation of the new bearings and putting EVERYTHING back together! :)

-- "can't died in the poor house" (Because he always went around saying... "I can't")



7 comments so far

View Rich's profile (online now)

Rich

1854 posts in 400 days


#1 posted 01-25-2017 03:31 PM

What a great project. The level of detail in your work is impressive. I’m really looking forward to seeing how it turns out

-- No matter how much you push the envelope, it'll still be stationery.

View ShaneA's profile

ShaneA

6846 posts in 2409 days


#2 posted 01-25-2017 03:53 PM

Nice detail, and pictures.

View N2wood's profile

N2wood

22 posts in 509 days


#3 posted 01-25-2017 05:50 PM

I’m looking forward to your follow up post. This is an area that I need to learn more. Thanks.

View maxhall's profile

maxhall

72 posts in 2012 days


#4 posted 01-26-2017 03:29 AM

Before you remove that endbell I would put a piece of tape across the piece where it mates and draw a vertical line on the tape so you can easily line it up. Also take copious amounts of pictures and put everything in labeled baggies (found that out the hard way). I also have a good method for putting the new bearing in place. I’ll be following along and willing to help if possible.

View RichmanNot's profile

RichmanNot

39 posts in 322 days


#5 posted 01-28-2017 03:54 AM

OKAY… I apologize for the lag in getting this going again, but here we go.

Good advice offered above by maxhall which I will repeat here: Before you remove that endbell I would put a piece of tape across the piece where it mates and draw a vertical line on the tape so you can easily line it up. Also take copious amounts of pictures and put everything in labeled baggies.

(I used a small plastic jar for the small parts)

When I left off, I was at the point where I was about to get into the “guts” of the motor. The (4) long bolts have been loosened on the back end of the motor, and what you need to do is either use a plastic dead-blow hammer or a small block of wood with a hammer to give a few light taps on the END of the shaft protruding out of the back casting. Gently “whack” on the end of the saft and it will “PUSH” the rotor out the front of the housing and force the front end casting to separate and come off of the motor housing.

As you begin to see the separation take place keep a free hand available and as the rotor begins to be exposed, take ahold of the casting allowing it to slide out of the housing keeping it “balanced” to avoid “dragging” on the “WINDINGS”. Once the rotor is out it is still connected to the front casting, and the next step is to remove the rotor from the front casting, and then proceed to the task of removing the “front bearing”.

As the rotor and front casting are now free, the rear casting will also now be able to be removed.

Once again you will have some cleanup! It seems that sawdust can get into everything on the motor!

The shopvac took care of the loose sawdust, later I will describe how I used an air gun to blow out the motor housing and cleaned the “windings” back to “like-new” condition.

At the front casting there are (2) flat head screws. These hold a ring that is located behind the front shaft bearing. Loosen and remove the two screws now.

OK… grab that dead blow hammer (or your block of wood and hammer) and tap on the end of the shaft to free the shaft from the front casting .

Next it is back to choosing the right configuration of puller arms on the gear puller so the front bearing can be removed (pulled) off of the front pulley/rotor shaft.

Before we go to that step, let me show you the opposite end first! On the rear end of the rotor shaft where we removed the “rear fan” previously, there is a device on the shaft which it typically called “the starter” (although that is probably a layman’s term and not the correct term). The correct terminology and description is that it is a “Centrifugal Switch”. The device is an electrical switch which operates on the centrifugal force of the spinning rotor shaft and it activates and deactivates the starting winding thus the term starter switch it essentially releases the starting winding once the rotor reaches its normal operating speed.

More information can be found on WikiPedia in case you are curious for more details on this function of this device

For your motor tear-down here it is prudent to just take a look at the device and see if it “LOOKS”OK… No signs of damage or loose parts. The springs should be looked at and anything out of the normal will be pretty obvious.

OK time to get that bearing removed!

Once you have the gear puller in place, grab a heat gun (or your wife’s hair dryer). Put some HEAT to the old bearing! My heat gun can get pretty hot!

(The HF heat gun claims it can get up to 1,112 degrees – and I believe it will)

Just use the low setting and try and heat the bearing uniformly by rotating the rotor as the heat is applied. Once you think it is pretty well heated up, try tightening the gear puller nut. (I was unable to hold the puller against the force of the pressure – so I engaged the puller side between the vice jaws to restrict the twisting effect which allowed me to continue the tightening of the nut.

WARNING! DO NOT BE TEMPTED TO USE THE VICE JAWS ON THE ROTOR OR ROTOR SHAFT! NO, NO, NO!

I was glad to hear that “SNAP” sound—as that is when I knew the bearing had been pulled free!

Remember that “RING” well here it is. It sits behind the bearing and essentially holds the front casting on with those two slotted head screws.

NOTE: The front cooling fan remains on the rotor shaft and need not be removed. I noticed some spots of rust on the rotor, but I did not do anything to them, the rust was not severe and won’t affect the rotor function.

OK turning now to the rear casting… This is the “business end” of the shaft. The rear casting has the electrical components (the contacts) and in my case it has that small red reset device (again your motor may not have one)

The “contact device” is held to the rear casting by (4) flat head screws seen here. Remove the screws, treat the contact device “gently” it will remain attached to the winding on this end of the motor. Be gentle also with the wiring here!

Once you have removed the “CONTACT DEVICE” held by (4) screws to the rear casting, set the casting down. Looking at the inside of the casting, you will also see a “flat-head screw” that screw is what holds the rear bearing down in a well in the casting, Grab a flat screwdriver remove the screw and bearing.

YEP… Time for more housecleaning. Vacuum the sawdust from the parts BUT be very careful with the contact device! DO NOT TREAT IT ROUGH! Later you will need to “clean” the contacts with some fine emery paper (or a ignition points file)

ALL RIGHT….SUCCESS! We have the motor apart. All that is left to do now is some more cleaning (and in my case a new paint job) and we can move onto reassembly!

So until next time… I will try and post more pictures of the clean-up I did plus my “masking and painting” of the parts, then the re-installation of the new bearings and putting EVERYTHING back together! :)

-- "can't died in the poor house" (Because he always went around saying... "I can't")

View N2wood's profile

N2wood

22 posts in 509 days


#6 posted 02-02-2017 11:47 PM

Can’t thank you enough for this thread. I just picked up 4 motors today and one of them needs a bearing. One of them is an antique Leland. Two were freebies so I wasn’t concerned. For $50 bucks And the 1 hp 1 phase Dayton is in great shape. Now maybe I can start on a band saw build. I am looking forward to seeing your final post.

View RichmanNot's profile

RichmanNot

39 posts in 322 days


#7 posted 02-03-2017 12:44 AM

N2wood… I have posted the final post which describes the reassembly. There are 3 parts to this motor restore. Thanks for your comments, Regards Richard.


Can t thank you enough for this thread. I just picked up 4 motors today and one of them needs a bearing. One of them is an antique Leland. Two were freebies so I wasn t concerned. For $50 bucks And the 1 hp 1 phase Dayton is in great shape. Now maybe I can start on a band saw build. I am looking forward to seeing your final post.

- N2wood


-- "can't died in the poor house" (Because he always went around saying... "I can't")

Have your say...

You must be signed in to post the comments.

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

HomeRefurbers.com