Kysor/Johnson Horizontal Bandsaw: Part 3 – The Gearbox

I’m back with the third installment on fixing the KJ horizontal bandsaw.  This time I’m addressing the gearbox that drives the back wheel.  The gearbox has a few problems that I have to fix.

The gearbox is above the backwheel and requires a good bit of disassembly to remove.  I’m taking it all apart so it’s not a big deal for me.  It’s the boxy looking thing in the following pic.

Here’s a view from bottom of the wheel.  The input shaft of the gearbox is driven by the motor and the output shaft has a small gear on it that turns the large ring gear bolted to the wheel. You might be wondering what the giant blob is on the end of the small gear.  It’s welding filler metal.  A giant blob of filler metal.  The gearbox is held on by three screws.  These screws thread into three bosses on the gearbox.  As you can see, something bad has happened to two of the bosses.    The other boss is not pictured and is fine.  The boss on the far left is not used.  The gearbox has a back plate that can be removed to access the inside. I wasn’t really sure how to disassemble the gearbox but eventually determined that the short shaft has to be removed first through the open back which requires moving the small gear.  I wasn’t sure if the small shaft stuck up beyond the surface of the gear.  Since I didn’t want to damage the shaft, I took shallow passes on the the mill to remove the filler metal.  Once I got down to the surface of the gear I could still see filler metal in the middle.  I tapped the center with a ball peen hammer and broke the last little bit of filler metal out.  Once I got the small gear off I could see the damage to shaft.  I’m guessing the saw blade jammed and this was the weak point.  Someone attempted to fix it by welding the gear back on.  What they actually did was put a “cap” of weld over the end that didn’t touch the shaft at all.   I guess that was good for me as it made getting the gear off easier.  There was some damage to the large brass gear but I was able to file away most of the burrs.Next, the large shaft could be removed.  Both shafts had a plastic and rubber oil seal that had to be removed from the protruding side.  Then there’s a snap ring to be removed.  The other end of each shaft had a plate that covered another snap ring.  Finally, with all the snap rings removed, the long shaft can be pressed out.  There was a mix of shielded, sealed, and open ball bearings in the gear box which makes me think someone else might have been in here before.To fix the broken threaded bosses I decided to mill them flat and turn some spaces to take up the space.  The boss on the right ended up being taller and I was able to tap the hole a little deeper.  The one on the left required drilling through the casing in order to get enough threads to hold a bolt well.  I plan to use RTV on this bolt so it won’t leak.I decided to weld the broken end of the shaft as opposed to remaking the shaft entirely.  To start I ground the end of the shaft to clean it up as shown below.  I then welded on the end of the shaft to build the surface back up.  Next, it was over to the lathe to clean it up.  I repeated these steps over several times until I was happy with the results.  To finish it off, I milled a new key way.  Here’s the repaired shaft.  Hopefully, it’ll hold up.  The gear fits tightly on it and I used some green Locktite upon reassembly.With all the problems fixed I started reassembling the gear box.  I decided to use sealed bearings when reassembling in hopes that it would help some with leaks.Here’s a pic of the insides of the gearbox before closing it up.Instead of paper gaskets I used RTV to seal up the gear box.  I also bought a new small gear to replace the broken one.  The new gear is taller than the old one and would interfere with spokes on the wheel.  So, I took my brand new gear to the mill and removed part of it. 

Here’s the finished gear.Next up starting to reassemble the saw.

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Kysor/Johnson Horizontal Bandsaw: Part 2

I’m finally back with another update.  For a while it was too cold to paint and I’d been busy with some other things around the house.  Once again, I’m making progress on the KJ saw.

As you might imagine, de-rusting has ended up being a large part of this project.  For most of the big parts I’m using a wire cup on an angle grinder.

I thought about how to fix the crack in the leg and eventually decided on stick welding it cold in short runs.  After each short run I peened the weld while it cooled to help prevent cracks. I don’t have the ability to heat something this large up which ruled out brazing and stick welding it in one pass.  Before welding though I Veed out the front and back of the crack with a carbide burr.It’s not the prettiest weld I’ve done but I think it worked out ok.  I used some 55% Nickel rod which was a first for me.  There’s a bit of undercutting but there’s no more crack.  As this isn’t a highly loaded part I think it is a successful repair.  I started thinking about paint and Chris pushed me to go with something other than grayscale.  After looking around for a bit I settled on Rustoleum’s Royal Blue.  I started painting with it but found it was too bright for my liking.  It was brighter than what was on the can which wasn’t what I was looking for.  I mixed in black paint and finally ended up with a shade that I liked.  In the picture below you can see the darker paint on the lower bit of the leg in the foreground.  Eventually, I was able to start painting.  The paint looks a little brighter on the big leg for some reason but it’s all the darker blue.  I hand brushed these and the center section below.Here’s the center section getting its coat of paint.  Don’t worry, the blue inside the hinge holes is just masking tape.  Originally, I painted the wheels blue but changed my mind and went with black.  I spray painted these which was much easier than trying to brush them.The pans that came with the machine were torn up and had been cut down.  I don’t have the machines to remake the pans but a guy I know works in a machine shop.  I talked to him about it and he offered to help.  He was able to water jet the pans out and we were able to get them bent on his machines.  Below is my pan getting bent on a 400 ton press brake.  Cool!Here’s one of them in place and the other is hiding in the background.The next step in the project was to replace the bearings on the wheels.  From some online research I found that the bearings are standard wheel bearings that can be picked up at a local autoparts store.  That’s a positive.   There’s also some dust covers on the outside of each bearing that are hard to find.  I eventually came up with a method to remove the dust covers without tearing them up.

I’ll describe what I did even though it might not be useful to anyone.  There are two dust covers, two cone bearings, and two races in each wheel.  The assemblies are mirrored and there’s a snap ring in the middle of the bore.  Due to the snap ring, you can’t just push it all out from one side.  I ended up cutting a 1/2″ fender washer into three pieces and slipping them in between the two races.    Next, I used a 1/2″ bolt, other washers, and a nut to hold the three washer pieces .  You want to hold them as close to the edge of the bearing bore as you can so they don’t bend.  I then used a 3 jaw puller to push the cone bearing and dust cover out. One bit out.I now have more room to work on getting the other assembly out.  I used a fender washer again but cut into two pieces.  Once again I held the washer pieces with a bolt and pushed the other race, cone bearing, and dust cover out.Finally, I turned a piece on the lathe to push the first race out.

Here’s all the pieces I used to remove the bearing and dust cover assemblies.  I ended up with a few dust covers that were a little bent but was able to straighten them back out.

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Kysor/Johnson Horizontal Bandsaw

Thanks to Gill I have yet another tool to restore and put into use.   This is a good thing of course because I still had a little bit of empty space in my garage.  This time, it’s an old industrial horizontal band saw.  I believe this saw was made sometime between 1973-1985.  It’s a bit rusty but appears to be in good shape.  The motor mount is missing but it shouldn’t be much trouble to make are replacement.

The motor is connected to the gear box via a belt.  The gear box drives a gear connected to the drive wheel.  The other wheel (idle wheel) is used for tensioning the blade and is supposed to spin freely.  Below is a pic of the idle wheel and tensioning knob.  There’s a small piece of the rim on the wheel missing but I don’t think it will cause an issue.

Here’s the drive wheel.  There’s supposed to be a mechanical lubrication pump on the  bracket but it is long gone.  You can also see the gearbox and big internal gear.

The blade guides also appear to be in good shape.  One of them was broken and has been repaired.  Despite what it looks like everything still moves.  Here’s another view of the drive wheel and the hydraulic cylinder.  The saw cuts due to its own weight and the hydraulic cylinder slows its descent.

I started disassembling the saw and was pleasantly surprised that everything came loose easily.  I sprayed on some PB Blaster a few days before starting which may have helped.  The first repair was to straighten the tension knob with the arbor press.  I’m not 100% sure how it got bent but the instructions do say to tension the blade as tight as you can.  Maybe someone took it to heart.

To remove the cutting section of the saw you have to separate the frame halves.  I was hoping to remove the axle and lift the entire cutting section off but it didn’t work out.  Instead, I supported the half that holds everything with the engine crane and removed the other side half by hand.  After that I laid the half in the picture down to continue disassembling it.

  I couldn’t get the drive wheel and gearbox out with the halves together.  As you can see the little gear from the gearbox runs on the inside of the larger internal gear bolted to the drive wheel.

The main axle has shoulders that keep it from being driven out with the side halves on.  There’s a grove in the axle that the little tab fits into.  I think this can be used to move the entire cutting section of the saw side to side.  It is a bit crude but I guess it works.  This pic also shows the mangled pans on the saw.  I don’t think they’ll every be straight again.  The legs are held on by a few nuts and bolts.  I supported the lower half of the saw with the engine crane to allow removal of the legs and then sat the bed down.

Here’s a pic of the rear leg which has so far been hard to see in the pics. 

Someone had broken a bolt off in the end of the axle shaft.  I tried vise grips on it but without luck.  I then tried the “weld a nut to it technique” and it came out easily.  I think this is one of my favorite things about owning a mig welder.

I removed the wheels from their axles and ran into what I’m guessing are the original bearings.  They feel stiff and gritty and will at least require new grease. 

Now for the some bad news.  Two of the three posts that the bolts go into on the gear box are broken.  Someone also welded the little gear onto the shaft and I can’t imagine that’s a good sign.

I also discovered a rather large crack in the main leg.  It runs most of the way across this foot and I’ll have to find a way to repair it.

People must like these saws because they’re still made today by the Dake company.  The castings have been greatly simplified because all industrial machines made today are not allowed to have character.  They’ve also made the hydraulic system easier to use and covered all the moving bits.

More later as the restoration continues…

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Hardinge HLV Part 4: It Runs!

I’d previously tested the control system on the Hardinge by directly hooking it to a 240V receptacle but now I’m up to the point of needing a more permanent solution.  I thought about it some and decided that feeding the control system independently of the motor power was the best option.  So, I took the two non-generated hot lines from the breaker box and hooked them up to what was labeled as the hot and neutral lines for the controls.

The hot leg in the diagram would have had 240V so using my two 120V lines provides the same voltage potential to the control system.  This new hot leg (former neutral) could cause problems though because it isn’t fused.  So, I put a fuse in line to match the one on the hot line.

The lathe makes use of some older European style fuses that seem to be hard to find and relatively expensive.  They’re labeled F4 and F5 on the holders in the pic below.

I removed the fuse holder and replaced it with a more common style.  Surprisingly, the holes matched up.  There are three more of the Euro style fuses which power the coolant pump but I don’t plan to use it.

I decided to take a look into the coolant tank though and it was a bit messy.    It cleaned up pretty well though and there were no rust holes.   I did all this a couple months ago but the project was put on hold while I was trying to find a tool post.  Happily, Gill messaged me one night to say that his father had randomly found a tool post and sent it to him.  So, I was able to get a new import tool post pretty cheaply.  I fit the post to the compound and prepared to take my first cut!  I put some aluminum in the collet, locked it down, and then proceeded to just push the aluminum in some.  After some fiddling with the collect locking mechanism I got it to hold correctly and proceeded to make some nice chips!  Well, strings.  Finally!    Now I need to get some carbide insert tool holders for it. Here’s a video of the first cut using the power feed.

I’m almost done with the Hardinge.  The only thing I have left to do is replace the bronze nut in the tail stock.

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Hardinge HLV Part 3: Feed Motor

I’ve finally gotten back to working on the Hardinge.  This time I’m addressing the feed motor on the carriage.  When I hooked it up previously, I was disturbed to find that the motor only ran in one direction despite the direction switch being changed.  I checked it out with my multimeters and found that the switch worked fine and was reversing the voltage.  I started checking out the motor a discovered that one of the field motor wires had continuity with the motor’s case.  Not good.

The motor is a right angle 240V DC motor that moves the carriage and cross slide.  This isn’t a motor that would be easy to buy a replacement for.  So, I decided to dig into it and see what was wrong.

Since I had continuity between the field coils and case I knew that I was looking for some kind of contact between the two.  A field coil is just a continuous piece of coated wire folded into a bunch of loops. When electricity is connected it generates a magnetic field.  Once I opened the motor I quickly found a charred area.  Here’s a better view of the charred area.  As the coil is a continuous wire, any break in the wire means the coil won’t work any more.  Electrical contact between the coil and the motor frame will also cause problems as it shorts to ground. 

Other than the bad coil the rest of the motor looked fine.  So, I started trying to figure out how to fix it.  I took the motor around to a couple of motor shops but most didn’t work on motors this small.  One did but said they wanted $250 + parts to fix it.  Me, being cheap, though about possibly winding the coil myself.  Sure, I’ve never wound a coil before but it can’t be that hard right?

First, I took some measurements of the bad coil.  The wire was 34 gauge magnet wire and I was able to get a spool off of eBay.  I also made some drawings of the coil and thought about how to wind it.  I measured the resistance of the other coil and found it to be 944 ohms.  I looked up the resistance per length of the wire to figure out how much wire would be in the coil.  The result?  3,557 ft of wire.  About 0.67 mi or a little over 1 km.  Looking at the bad coil I could see that there were an uncountable number of turns in the coil.  I did some math on the coil and decided that I needed about 4500 turns in my coil.  I planned on doing more turns than that because my winding would be more random than my mathematical model.

To count the turns I picked up a magnetic switch and wrote a Arduino program that would count up every time the switch was closed.  I stuck a small magnet to the lathe’s chuck and mounted the magnetic switch near it.  I tested it by hand to make sure it worked as planned.  Once the bugs were worked out, I turned on the lathe and watched the output on my netbook’s screen.  The program steadily output the number of revolutions and current RPM.

Given that many turns I’d definitely want to use the lathe.  The bad coil is rigid and lumpy which made it hard to measure with much precision.  If the coil were flat it wouldn’t be that hard to wind but this one is curved.  I thought about the possibility of winding a coil flat and bending it.  I eventually talked myself out of that and tried to figure out how to wind it in place.  Luckily, some PVC pipe has about the right size inside and outside radii to match the bend of the coil.  With the PVC and some MDF I built a curved form. I quickly found out that I’d have to hand guide the wire or design some kind of mechanism to guide the wire.  I started trying to hand guide it and found that the max speed I could achieve was 17 rpm.  At that rate I’d be there about 5 hours.

So, I went back to the idea of winding the coil flat and bending it.  I made a much simpler form, worked the bugs out, and started winding.  Once I got to around 4700 turns I stopped winding, crossed my fingers, and cut the wire to measure the resistance.  It was right at the resistance I needed.  (In retrospect this wasn’t a good sign as I did 200 extra windings and should have been greatly above the desired resistance.) I pulled the coil off, taped it together in spots, and found it would bend without issues.  Next, I tried to fit it in the motor frame and found it wasn’t wide enough.  Ok…I just call this one the prototype.

Comparing my prototype to the bad coil I found that I needed to make my new coil about 3/4″ wider.  I used the same form design for the prototype and this coil.  To aid in bending I made the width of the form increase over the outer 1/2 of the coil thickness.  I don’t really know if this made a difference but it seems like it would in my head.  The form is in two pieces to enable me to remove the coil.  The center hole is for mounting on a bolt and the smaller holes were for string that I placed before winding.  After winding, I would carefully remove the top of the former and use the strings to keep the coil together.

I put the form in the lathe and set the lathe’s speed to 90 rpm.  I positioned the spool of wire on the carriage and the netbook in a good spot to easily view it.  If you look carefully, you can see the magnetic switch (attached via blue tape) and magnet on the chuck.  I turned the lathe on and started winding.  I found it better to guide the wire with my fingers to even out the bumps in tension and get the wire where I wanted it.  I shut the lathe off periodically to check how it was winding. After about an hour, I arrived at 4700 turns and checked the resistance again.  It was a lot higher than I needed but that’s ok.  I unwound turns off and checked the resistance frequently until I got the resistance I wanted.

Tada!  I marked the inside of the coil so I wouldn’t forget which side was supposed to be inside.

I wrapped it completely in tape leaving the ends hanging out.  Playing with the prototype coil, I found that it would bend but wouldn’t hold the shape which isn’t surprising.  It would stay bent some though. 

To see if I could permanently bend it I put into the pieces of PVC from my curved form and left it sitting for a few days.   Unfortunately, but not expected, it didn’t hold the shape.

After that I decided to see of I could hold it in place with some spray varnish I bought for insulating coils.  From what I’ve read, normally coils are dipped in a varnish to protect them but didn’t want to buy an expensive can for a one time use.  I tried the spray instead, which isn’t really a varnish.

I soldered some thicker wire onto the coils ends and tapped them in place.

You may recall that a magnet has two poles: North and South.  The magnetic field of a coil also has two poles.  The orientation of the poles are determined by the direction that the electricity flows through the coil.  Looking from the inside of the coil, my coil is wound counter clockwise though this isn’t critical.  More on that in a few.  To determine the orientation of my magnetic field, I used a compass and ran 12V DC through the coil.  As you can see, the North pole is to the left and the South pole to the right in the pic.  To change the direction of the poles, you swap the positive and negative wires.  To hook up easily to the existing coil is the reason I wound mine CCW.

The new coil has to have its magnetic field in the same direction as the other coil.  To check this, the wires are hooked up to the other coil and the compass direction is noted.  I actually, checked the direction of the magnetic field on this coil before winding but I’m showing it here.

I spray varnished my new coil in PVC bender showed above but once again it didn’t hold its shape. 

Finally, I decided on epoxying the outside of the coil.  Some coils are dipped in epoxy which penetrates the entire coil but the bad coil didn’t appear to be dipped.  So, I settled for brushing on some epoxy in my modified form. Plastic wrap was used to keep the coil from sticking to the form.

I ended up with a horrible finish but the coil held its shape!  I tied the coil in place like the other coil but didn’t get a picture of it.  After that, I replaced the bearings on the armature, trimmed, and soldered the wire before reassembling the motor.  Next, I checked the motor over to make sure I had continuity where expected and that there were no shorts to the case.

Finally, I hooked the motor back up to the lathe and gave it a try.  It actually works!!  I expected it to of course but I still half way expected the magic smoke to come out.  I tested it apart from the carriage to make sure it moved and went in both direction. After the successful test, I reattached it to the lathe, filled the oil reservoir in the carriage, and tested it again. The speed and direction worked correctly.

This is a short video of winding the prototype coil:

This is a video of testing the feed motor on the lathe:

 

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Wooden Fletcher Class Destroyer

For some reason I decided to make a wooden model ship of the US WW2 Fletcher class destroyer.  I attribute it to reading Sea of Thunder.  I used 1:350 scale like those used with some plastic models.

I looked around online for some drawings of the ship and stumbled across a picture on shipbucket.com that I liked.  It seems to be gone due to some changes on photobucket’.

The drawing had some profile lines for the hull which I tried to use.  I glued the profiles to the wood to aid in cutting on the bandsaw. I cut out the hull from one side, taped the pieces back together, and then cut out the top.    Next, I used rasps and a sander to finish off the hull.The ship’s structure using 1/4″ thick strips.  Once again, I glued the drawings to the wood to use as templates. I cut out multiple pieces to build up all the parts and used nails as the gun barrels.   It turned out that making everything was the quick part.  I ended up spending the next week getting all of the parts (mostly the hull) painted.  I went with the Measure 22 camouflage scheme which used haze gray on horizontal surfaces and a navy blue on the top surfaces.  Light gray and dark gray paints which I already had around were pretty close. Painting the hull was the hardest part of the project.  It required red, black, light gray, and dark gray stripes.  I masked the hull off and slowly got it painted.

For a mast, I glued together some thin steel rod I had laying around.  I assembled it over sized and then trimmed it down as required.  With everything finally painted, I was able to assemble it.

I thought I’d see if it floated….nope.  Well, technically it did float. It just wanted to capsize.  Oh well.  Maybe the Yorktown next!

 

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Inspecting an AC Motor

I got another single phase AC motor for free.  This one is an older GE single phase dual voltage 1hp motor.  The cradle mount is missing and I’ll have to deal with that later.  Currently, I’d like to check it out to see if it will run.  Here’s a picture of the motor.  It was missing the cover over where the wires connect and I made a new one from some scrap.

Sure, I could just hook the motor up and flip the switch but that’s not the best approach.  You could damage the motor or shock yourself if something is wrong.  Both are not desirable. There are a few checks that can be done first before trying to run the motor.

The first is a simple mechanical test.  Does the motor spin freely?  On a single phase motor, you will hear a slight rubbing from the centrifugal switch but other than that the armature should spin easily.  Are there any nuts or bolts missing from the front or back.  Usually the ends of the motor are held on with long bolts that go from one end of the motor to the other.  There should be a nut on the end of each bolt.  Sometimes the end bells are directly bolted to the middle of the motor.  Either way, make sure the end bells are attached to the rest of the motor.

After the brief mechanical inspection is done, it’s time to move on to an electrical inspection with a multimeter.  Most of this can be done without disassembling the motor but I’m going to for clarity.  Disassembling this motor is pretty simple.  First, the nuts are removed from the long bolts to allow the bolts to be removed.  Next, the end bells are removed by tapping them off with a hammer.  This motor has little pockets on the end bells where a screwdriver can be placed to tap the end bells off.  You’ll want to mark the orientation of the end bells to the body of the motor before removal.

Sometimes with an open motor you’ll want to take apart the motor just to clean it out.  Dirt and other gunk can get sucked into the motor which can cause overheating.  Keep an eye out for any shims that may be in the motor.  You’ll want to put the mall back in in the same orientation as they came out.

In theory an induction motor is a pretty simple device.  There are loops of wire called windings that AC voltage passes through that are fixed to the body of the motor known as the stator.  In the middle are more loops of wire on the rotor which turns.  The AC voltage in the stator creates a rotating magnetic field that interacts with the rotor causing it to spin.  A single phase motor won’t start on its own.  One way to start one is to add some more windings (start windings) on the stator in series with a capacitor.  The capacitor shifts the phase of the current in these start windings which helps start the rotor turning.  The start windings and start capacitor will burn up if left running though.  To remove them from the circuit, a centrifugal switch is used which switches when the motor comes up to speed.  Sometimes single phase motors have a second capacitor called a run capacitor.  It’s not the same as a start capacitor and does keep working when the motor is running.

On my motor there is also an over overload device that will shut the motor down if it overheads or draws too much current.  It is a normally closed switch which opens if a small piece of metal becomes too hot.

This motor is currently set up for 115V though it can be setup to run on 230V.   The voltage is selected by moving some small metal links which change the way the windings are connected.  For 115V the windings are wired in parallel and for 230V the windings are wired in series.   Here’s a little drawing of the wiring in the motor.  The ovals with two dots represent the metal links for this motor.  With the diagram, you can see multiple things can be tested such as continuity through both windings and the start winding, operation of the centrifugal switch, continuity through the overload devices, and the capacitor.  Note that any  resistance values are specific to my motor and probably don’t apply to others.Here’s a view of the end of the stator with all the interesting bits.  The black circular object is the overload device.  The wishbone looking thing is the electrical part of the centrifugal switch.  Finally, there’s all the wires, metal links, and posts for the motor line connections.

The first electrical test, is to check for continuity through the windings.  This is done by checking the resistance with the meter hooked up to the two line connection posts.  With the windings wired in parallel there’s a possibility that one of the windings is burned out.  To check, the metal links would need to be switched to the 230V setting and continuity checked again.  Alternatively, if you have a diagram of the motor, each winding can be checked separately.  I look for a low, but not zero, resistance value.  An open would indicate a failed winding or bad connection.

Next, is to check for continuity between the windings and the motor casing.  This is done by checking continuity between one line connection post and the casing.  You’ll need to find bare metal on the casing such as a screw hole or screw threads to connect to the motor casing.  For this test, I expect an open result otherwise the winding is contacting the motor casing which should trip a breaker or shock you.

The electrical part of the centrifugal switch is a simple switch.  When the motor is stopped the switch should be closed and opens when the motor is up to speed.  On my motor, without the mechanical part of the centrifugal switch in place the electrical switch is open.  I can close it by gently pushing on the wishbone.  If it doesn’t respond as expected check for loose wires or dirty contacts. The mechanical part of the centrifugal switch consists of some spring loaded weights that fly out when up to speed pulling the plastic piece down on my motor.  It should be checked to make sure it opens freely though not effortlessly by pushing down on the plastic piece.

On a capacitor start motor, the capacitor is usually on the outside of the motor under a metal cover.  Before you start messing with the capacitor be sure it is drained by putting a good sized resistor across it or connecting the two posts with a piece of metal that you’re insulated from such as a screwdriver.    Ideally, you’d check the capacitor with a capacitance checker but not everyone has one of those.  If you don’t there are a few makeshift tests you can do.  After the capacitor has been drained, disconnect and remove it.  A multimeter can be used to measure the resistance of the capacitor.  You shouldn’t get a low or open reading.  On mine I got around 14 megaohms.  Another way to test is to drain the capacitor and check the voltage.  It should read zero.  Then hook a 9V battery up to the capacitor for around 10 seconds.  Remove the battery and check the voltage across the capacitor.  You should see that the voltage is no longer zero and somewhere near 9V.  Mine was around 7V and slowly decreasing.  If you short the capacitor you should see a weak spark.  The results indicate the capacitor should probably work.  These kinds of tests are about all you can do without a capacitance tester and none check the capacitor at the kind of voltage it will operate at.

The overload device on my motor can also be checked for continuity.  It has three posts and should show continuity between all three sets of two wires.  If it does, it will let the motor run.  I suppose it could fail open or closed but there is no way I can think of to check the operation of it without specialized equipment.

I did some of the tests before opening up my motor and thought it should run.  I plugged it in and it ran.  It operated as expected but the bearings were noisy.  I ordered some replacement bearings and pulled the old ones.

The new bearings were pressed on with my arbor press. After that I did some more of the tests covered above before putting the motor back together. 

If you have a single phase capacitor start motor that won’t start but had previously been running well, there’s another simple test you can do.  Remove the load from it and turn it on.  If it still doesn’t start, quickly turn it off.  Find a piece of string and wrap it around the motor shaft.  Quickly pull the string off to get the motor shaft spinning and turn the motor on again.  If it starts up it’s probably the capacitor as the centrifugal switch isn’t likely to work fine one day and fail the next.  Obviously, don’t wrap the string around yourself or try to start the motor before the string is free of the shaft.

There are other tests that can be done on motors but hopefully these simple ones will help you get your motor running.

 

 

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