Predator 2000 Inverter

From my last post, you might have guessed that I had decided to look for an inverter generator.  After doing a bit of online research and reading reviews I ended purchasing the Predator 2000 Inverter generator from Harbor Freight.  This generator has a 1 gallon fuel tank and puts out 1600 running / 2000 starting watts.   According to the specs it will run for 12 hours producing 400 watts.  I haven’t tested it yet but have read where some have and got similar results.  Based on running it some it does sip fuel.  Weighing in at only 50 lbs the generator is also highly portable.

The front panel has two 120V receptacles and an odd shaped 12V receptacle. There is also a switch which puts the generator in “Eco” mode which throttles the motor down to the required speed.  Included with the generator is a set of 12V leads that end in two squeeze clamps and some cheap tools.   The generator is also able to be paired to another identical generator to generate twice the rated power output.

One nice thing about the generator is that they took all of the stuff that is actually important out of the owners manual, turned it into a sticker, and put it on top.  There are steps for how to start it, the max load, and fuel type.

Both plastic side panels of the generator are able to be taken off by removing three screws from each side.  From there the insides can be seen.  As this engine has no oil filter I purchased a magnetic oil dip stick to collect bits of metal that are produced while the engine breaks in.  I also added an hour meter to help keep track of runtime for maintenance.  The meter runs off of 12V which I got by slipping wires on to the threaded studs on the back of the 12V receptacle.   It sits inside normally and I’m able to view it when I remove the side panel.  Ideally, it’d be nice to have it visible from the outside but I didn’t want to cut a hole in the generator case.One of the touted benefits of an inverter generator is that quality of the power produced.  Using a step down transformer I measured the voltage with my oscilloscope.   The picture below shows the results on the scope.  The wave appears well formed with no frequency distortion.  The frequency is almost perfectly 60 Hz.In case of a hurricane I’d like to be able to run a window AC unit, my refrigerator, and a few smaller items such as phone chargers and LED lights.  The AC and fridge were my big concerns since they’re the largest loads.  With this size generator I should be able to run both at the same time.  If both were to start at the same time it may overload the generator but I figure that is unlikely to occur.

As I mentioned in my last post, when anything containing a motor starts up there is a short time large current requirement.  This period of high current is called “inrush current”.  A the period of inrush current the current will drop down to near or less than the amount specified on the data plate on the device or motor.  My window unit lists the amps as 7.1 at 115V.  As my voltage is around 120 the running current will actually be a little less.  Power can the be calculated by multiplying the voltage times the amperage times the power factor.  Luckily, power is already listed on the data tag.  If the inrush current required by the AC is more than the generator can provide then it will kick offline and the AC will not start.

To measure the inrush current I used my Fluke 374 which has a special mode to do this.  When in this mode it will wait for a large spike in current,  take measurements for 100 ms, and then display the current.  Below is a picture of one of the AC start ups I analyzed.  Clearly, 30A is much larger than the listed 7.1A,  At 120V and 30A, 3600 watts  are required to start up the AC. For fun, I used my cheap current clamp and oscilloscope to show the  inrush current. Below is the startup of my AC.  The screen shot shows the current wave.  As you can see, after startup, there is a period of much higher current.  After this time the current then drops to the lower running level.  Also displayed are  two vertical lines which mark out 100 ms.  The values onscreen are calculated in this window.  The RMS value is 321.61 mV which converts to 32.1 A.  The values are not identical (probably due to several reasons I won’t go into) but are close enough for what I’m doing here.

The ability to provide increased output for inrush current is called “Starting Watts” on generators.  My AC needs around 3600 starting watts but the inverter generator only produces 2000 starting watts according to the rating.  When I try to start the AC off the generator it starts fine though.  When Eco mode is not turned on the generator doesn’t mind the AC starting at all.  If Eco mode is on then the generator slows a little before increasing RPM.  I’m sure the voltage sags when starting on eco mode but I haven’t measured it.  Maybe later…

Even though the numbers say my generator shouldn’t be able to start my AC, it does.  This is a good thing but it makes me wonder how the “Starting Watts” number is produced.  I looked online and in the manual but there is no mention of it.  I would think there should be a table in the manual that lists X number of watts can be produced for Y amount of time.  Since there isn’t it’s a buy and try thing which is unfortunate.  As far as I know, all generators are this way.

I was also worried about starting the fridge but it drew a much less amount of running and starting current.  Thus, I’m not discussing it as it is similar to what was shown above but with smaller values.

So far I have about 25 hours of time on the generator.  I runs well and I have no real complaints against it.  I did replace the spark plug with an NGK because some people have reported issued with the Torch brand plugs.  I’ve also never heard of Torch.  The instructions do say to slowly turn the choke off and I’ve found this to be accurate.  If the choke is turned off quickly the motor will stumble for a bit like any other motor.

Also, for those who may wonder I purchased the generator and it was not given to me to review.  But if HF wants to send me the larger version of this one I’d take it.

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Measuring Generator Fuel Consumption

Prepare for a bit of hack sciencing.  Since I live in a hurricane prone area I have a generator.  It’s a Generac 7550 running watts / 13500 starting watts standard open frame generator.  It’s always started, run well, and puts out power reliably.  My only complaints are that it drinks a lot of fuel and is loud.  That’s pretty much standard for these type of generators.  They consist of a gasoline motor driving an AC generator.  To generate 60 hz voltage the motor has to run at a little over 3600 rpm.  It does this when idling and under heavy load.

There’s a relatively new kind of generator out there called an inverter generator.  They use a gasoline motor to drive a DC generator.  This DC voltage is routed through an inverter to produce AC voltage.  As such, the motor doesn’t have to run at 3600 rpm.  Instead, it can adjust to provide the needed power and slow down when unloaded.  This paired with the smaller motors found in inverter generators results in them being quieter and more fuel efficient.  I was interested in getting one of these generators but wanted to be able to compare it to my current generator.   To do this I first needed to know the fuel efficiency of the generator I already own.  This is the subject of this post.

Here’s my current generator.  Please understand that I keep the generator in my unpowered shed and keep the battery inside my garage on a float charger 24/7.  When I periodically run the machine I just clamp the cables to the battery instead of fiddling with the tiny bolts.  Lazy?  Yes but it works fine.  If I actually had to use it in an outage I’d bolt the wires to the battery.

Now for the hack science.  In order to measure the fuel efficiency of the generator I need to be able to measure the fuel consumed.  While professionals might use a graduated burette or fancy electronics, I’m going to slap a gas tank on a scale!   But don’t worry it’s an old government postal scale which is reported to be pretty accurate.  My scale reads in increments of 0.1 oz which is accurate enough for this purpose.  The plan was to partially fill the tank which was hooked to the generator’s carbureator to run it off this tank.  I then ran the generator for 10 minutes taking weight readings at every minute.  I measured two load conditions: 0 and 1250W. This brackets my expected household loads in an emergency situation.  More on this in a future post. The unloaded condition is pretty easy to achieve but the loaded one had me looking around a bit.  I ended up using my electric smoker which was rated at the previously mentioned 1250W.  This has the added benefit of being a purely resistive load which means I don’t have to worry about real vs reactive power.  Note the little heater I had originally planned to use.  I’d forgotten it had a thermostat and would not come on in the outside temperature.

I also kept and eye on things with my Kill-A-Watt.  It confirmed the watts I was pulling.

Here’s the data I collected:

Load 0W Load 1250W
Minute Fuel weight (oz) Minute Fuel weight (oz)
0 69 14 57.9
1 68.1 15 57.1
2 67.3 16 56.1
3 66.6 17 55.3
4 65.7 18 54.4
5 65 19 53.5
6 64.2 20 52.6
7 63.4 21 51.7
8 62.7 22 50.8
9 61.9 23 49.9
10 61.1 24 49
Fuel burned 7.9 Fuel burned 8.9

As expected the loaded condition burned more fuel.  Since the fuel was measured in weight I need to convert it to volume.  To do this I can divide the weight by the density of gasoline which I found online to be approximately 0.426 oz/in3.  Also since amount of fuel burned in 10 minutes is not to useful I’ll convert it hours and days.

Doing the math I get:

Load 0W 1250W
Fuel consumption 111.27 125.35 in3/hr
0.48 0.54 gal/hr
11.56 13.02 gal/day

As you can see, doing nothing but making noise, the generator consumes about 0.5 gallons of fuel an hour or almost 12 gallons a day.  Loaded at almost 25% doesn’t really increase the fuel consumption that much.  Of course you wouldn’t run a generator 24 hours a day. But let’s say you run it for eight hours a day.  That’s still a minimum of 4 gallons of fuel a day or 28 gallons of fuel a week.  My neighbors had no electricity for two weeks after hurricane Ivan hit.

Inverter generators on the other hand get much better fuel economy.  For the most part, inverter generators come in approximately 1500W and 3000W varieties.  For example, a 1700 running watts Generac is rated run for 10.25 hrs at 25% load on 1.2 gallons of fuel.  A 3000 running watts Generac is rated to run for 8.9 hrs at 50% load on 2.6 gallons of fuel.

An inverter generator is vastly more efficient than a standard generator and much quieter if you can run within the 25%-50% running watts range.  On the other hand if you need more power and the ability to start hard loads standard generators are still your best bet.  Typically, the starting watts rating of standard generators are about twice the running watt rating while inverter generators only seem to give you a 400-500W difference.

More on inverter generators and a rant about starting watts in my next post.




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Wooden USS Baltimore: Part 3

In Part 2 I finished building the USS Baltimore. Now, in Part 3, it’s time for painting, painting, and more painting.

The first step was to spray everything with primer to make sure the paint adhered well.

My research online showed that the Baltimore spent its WW2 time in dazzle camouflage.  Specifically Measure 33/16D.  I also found some nice USN high quality pics of the ship at the Mare Island Navy Yard in California in Oct of 1944 at Navsource.  Online there was some text saying it went back to a more conventional paint scheme in 1945 but I could never find pictures to confirm it.  So dazzle camo it is.

Luckily, the official documents showing the dazzle pattern for this ship (and many others) are available online.   I printed them out to scale and then used them to sketch pencil lines on the hull.The hull has five different colors (mostly shades of gray): three on the vertical surfaces, two on the horizontal surfaces, and red on the bottom of the hull.  I worked from lightest to darkest color and started by masking the hull off.  Then I’d spray a color with my airbrush.  Then more masking and spraying.  I don’t know how many of these iterations I did but it was a lot.  Here are a few pics showing the process.

After FINALLY finishing the hull, I started on the super structure.  It’s shape meant I wasn’t able to tape as many things as I’d have liked.  Instead I used masking tape where I could and free-handed the rest with a brush. Then I worked on the big and medium guns.  The diagrams were a bit problematic for gun barrels.  The top view showed them at one color and the side view would show them at another.  As they’re round these both can’t be true.  So, I looked at the USN pics which showed them at the lighter color.Next ,came the support structures for the side mounted 40mm AAA guns.  There were some interesting patterns on them.As I was progressing, I realized I’d forgotten to make the Kingfisher float planes carried on the Baltimore.  I found a simple drawing of it and proceeded to scratch build a couple of them.  I roughly cut the pieces out on the bandsaw and then sanded/carved as required.  Tiny little buggers.I waited till near the end to put the masts and cranes on since I knew I’d probably just accidentally bump them.  I was not wrong.  Only a few more things to do now.Yay!  Finally finished and on deployment to the Tarpaulin Sea with the Fletcher (same scale).

Here’s a test for you.  Does dazzle work?  The Fletcher and Baltimore are both sitting out and I took some pictures from a distance.  Which way are the ships pointing?  Answer down below.

















Both ships are facing the same direction and at an angle about 40 degrees from the horizon with the bows closer to the camera.

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Wooden USS Baltimore: Part 2

After completing the hull in Part 1, it’s time to move on to the superstructure and guns.  My plan for making the superstructure was to print out the identification drawing at the scale I needed it.  Then, looking at both views, I broke the forward and aft superstructure into levels.  For each level I’d cut out a template and measure its height (or thickness for each piece of wood).  Below, you can see the forward superstructure’s six levels.  The number of levels may not match the actual ones on the ship but it’s a compromise between realism and reproducibility.

The templates were then traced onto 1/4″ thick wood to be cut out on the bandsaw.After cutting out the parts for the forward and aft superstructures, I temporarily put them in position on the ship.  Some of the parts were made of thicker wood and I still need to do some sanding on the rear exhaust stack.If you’re like me, you probably think WW2 battleships were big boats with big guns.  In actuality they’re floating anti-aircraft platforms with some big guns thrown on there too. It turns out heavy cruisers were built with the same idea in mind.  The Baltimore had 9 x 8″ guns (the big guns), 12 x 5″ guns (dual purpose surface or air guns), 48 x 40mm guns (air to air guns in groups of four), and 24 20mm guns (additional air to air guns).  The design principle seemed to be “If there’s an open spot stick some 40mm guns there.  If they won’t fit put a 20mm gun there.”  This isn’t surprising when you think of the primary threat at the time which were enemy aircraft.

I’m going to have 8″, 5″, and 40mm guns on my model.  I thought about trying to put the 20mm guns but they’re so tiny at this scale.  I started with the big gun turrets by cutting them out with the band saw.Then I drilled holes for the barrels.

To make the barrels, I trimmed down some nails.

The 5″ guns were done in the same way except I sanded them to shape.

Smaller nails this time.

The 40mm guns came two or four guns per emplacement.  The Baltimore had four gun emplacements.  The best idea I had was to make each emplacement out of a 1/4″ x 1/4″ square stick. Then I’d drill tiny holes for the barrels and cut slots into for detail.  To drill the tiny holes, I made a jig out of a piece of scrap.  

I made another “jig” for making the barrels.  Since the wire for the barrels was made from steel, I used a magnet to set the barrel length and then hold the barrels after cutting.

Next, it was time to assemble.  One of the emplacements has escaped in the pic below.

After I made all the guns I placed them on the ship to see what I thought.  Nothing is glued yet so I was able to tweak things as needed.

I then cut out a few more pieces for the aircraft related hardware.

About this time I started looking harder at the model of the USS Baltimore in World of Warships.  It’s much easier to see the ship in their 3D model than through old photos and drawings.  I found that some of the stuff in my drawing didn’t quite match up and there was some stuff I could improve.  From what I saw, I was able to make some new pieces for the superstructure that looked better.  Below is a piece for the front superstructure that replaces one of the original pieces.

I also replaced a few pieces that weren’t symmetrical.

Finally, I added some more details like the gun directors and some structures where some of the 20mm guns would have been.

I also started working on the masts.  I found it easiest to solder them as opposed to trying to glue the pieces together.At this point I’m largely done with building (though there are still some more details) and have started painting the ship.  Shockingly, it’s taking a while.

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Wooden USS Baltimore: Part 1

I’ve decided to make another wooden warship like my Fletcher.  This time it’s the CA-68 USS Baltimore from WW2.  This one will be in 1:350 scale like the Fletcher.  I wanted something bigger than a destroyer but smaller than a battleship and ended up with a heavy cruiser.   In real life she was about 673′ long by 71′ wide.  Here’s a picture of her from Navsource.

At scale my model will be 23″ long by 2.4″ wide and about 1.6″ deep.  This size is almost perfect for a standard pine 2×4.  Unlike last time, I’ll be using a softwood for the hull which is much easier to shape and lighter too.  Somewhere in the piece of wood below is the hull of a ship.  As a 2×4 is only 1.5″ tall I needed to add some more wood to the stem and stern of the ship where the deck rises.  After the glue dried, I trimmed most of the blocks off leaving material where I needed it.To start shaping the hull, I used a top and side view of the USS Chicago (another of the Baltimore class) from here.  Both the Chicago and Baltimore were turned into guided missile cruisers which radically reshaped the superstructure and armament of the ships.  I figured the hull was still the same which ended up being a mistake but that’s for a little later.   I scaled the drawings appropriately, printed them out, and taped them together.  Next, I cut them out and taped them to my block of wood.  Then I used the band saw to cut out the hull.  I cut the side view first and then the top which kept me from having to tape pieces back on after the first cut.

I used my stationary 4″ wide belt sander to turn large amounts of the wood into saw dust and shape the hull.  To profile the bottom of the hull I used some of the body plan lines that were included in the general plans.  I cut the available lines out after printing them on card stock and marked their locations on the top of the hull.  I then alternated between sanding an area and checking its profile.  Once I had all the areas close to shape, I blended the hull and hand sanded the entire hull down to 240 grit.  The hull’s shape is pretty close except for the front quarter of the ship which has a concave shape to the sides of the hull I was unable to duplicate with my method.      

After all the sanding I finally had a boat hull.  I next turned my attention to the superstructure and started looking for pictures of the ship.  The Navsource site had numerous good photos including one of the stern…that looked much blunter than mine.  It turns out they did reshape the stern in the conversion.  I looked for more plans but was only able to find a basic identification drawing of the ship which was probably ok for its purpose but not great for mine.  It’s all I could find though.  Below shows the stern of my boat along with the drawing.  Note that the stern still ended in the same spot but I’ve moved my ship some to show the aft end of the ship in the drawing. 

After all the work I’d put into the hull I didn’t want to chunk it.  After thinking about it a bit I decided to cut off the back of the ship and attach block to correct my issue.  Since this is end grain to end grain gluing, I drilled holes for dowels to reinforce the joint.

Once the glue had set for a few days it was back to the sander for more saw dust creation.

After all that I finally had a complete hull.Up next, I’ll start work on the superstructure where I’ll learn to dislike the identification drawing even more and learn just how many guns this ship had.



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Repairing the Rockwell-Delta 46-499 Lathe

A while back I bought a Rockwell-Delta 46-499 wood lathe.  The motor mount in it was a Jerry rigged affair and I decided to finally get around to replacing it.  The story from the previous owner was that his shop had flooded and he’d put a replacement motor in there.  I’m guessing the replacement motor (which is double the power of the stock motor) wouldn’t fit in original location because he’d put it on this hinged board thing.  It worked but you’d often hear the motor flopping around and the angle of the motor shaft resulted in the pulley walking its way off eventually.

From the factory, the motor bolted to a plate which was bolted to a raised panel in the back of the cabinet.  This raised panel is shaped like a very short hat stringer and is welded in.  The panel has three studs sticking out of it for the motor plate to bolt to.  One of the studs was broken off and I managed to break another trying to remove a nut.  I got the bright idea that I’d grind the welds off, remove the back panel, replace the studs, and reassemble it.  I quickly found out that there was no easy way to get to the welds.  I tried a burr and a small cutoff tool to no avail.  In the picture below, I’ve removed the motor and part of the speed adjustment mechanism.  You can see the one remaining stud and the three holes where the hinge was bolted.

After my lack of success removing the back panel I came up with plan B.  I decided I’d weld a plate to the back panel with holes tapped for bolts to hold the motor.  During this time I also pulled apart the motor, replaced its bearings, and put a quick coat of paint on it.  The picture below shows the machine viewed from the bottom while I’m trying to determine where the new plate and the tapped holes in it need to go.  The slots in the motor base will allow me to move the motor and tension the lower belt.

After everything was marked out, I drilled and tapped 5/16-18 bolt holes in the plate and welded it into position.  Next, I gave the inside lower half of the cabinet a coat of paint.

Once the paint dried I installed the motor and put all the belts back on.  Getting the motor adjusted and tightened down is a bit of a pain due to the lack of space.  Luckily, I don’t plan to adjust it often but I do understand why Rockwell-Delta went with the design they had.

I also took time to check out the other bearings in the machine.  The speed adjustment mechanism uses a Reeves pulley setup which rides on a shaft with a couple bearings.

The Reeves pulley is made of aluminum or zinc and I was fearful of breaking it.  As such, I wanted to remove the shaft without taking the pulley off.  To do this I used a bearing splitter and a puller to push the shaft with pulley out of the casting.

With the shaft removed the old dry bearings were hammered out and new ones pressed in.  These bearings had the same OD but different IDs which means you have to be careful not to get them mixed up.  

I also wanted to check out the bearings in the head stock.  I found out that the rear one was a little gritty and replaced it.  The bearing in the machine was a shielded bearing which probably let fine dust in.  I replaced it with a sealed bearing which should help the new bearing last longer.

I wanted to remove the spindle to get at the front bearing.  (I later realized I didn’t have to remove the spindle to do this though.)  The spindle assembly has a pulley on it which is keyed to the shaft and securely held in place by the rest of the assembly.  So, there’s no way this pulley can slide on the shaft once it’s all back together.  I tried to remove the pulley and found that it was securely held in position.  After bringing out the large puller and applying heat, the pulley finally came loose.  Afterwards, I could see where red loctite had been used to….do nothing but frustrate the person trying to remove the pulley I guess.  If you look closely you can see where the pulley has been previously broken and poorly repaired.  I left the pulley alone even though it doesn’t run smoothly but there’s no easy way to fix it. With the new motor mount in place the lathe runs a little smoother.  I had hopped it’d run more quietly as well but it doesn’t  The metal cabinet acts like a speaker box and amplifies the sounds inside.  Oh well, it still works superbly!

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Identifying Bad Ball Bearings

Ball bearings are an integral part of all kinds of machines around us.  They are found in most anything that has rotating parts such as cars, machinery, appliances, electric motors etc.  These bearings can range in size from smaller than a grain of rice up to 12 ft in diameter according to a website I found.  (Some different types of bearings are even larger!)  The size bearings I regularly deal with when restoring machinery are of a much more benign size in the 1″ to 3″ range.

When I go through a piece of machinery I like to check out the bearings.  I say “check out” instead of inspect because bearing health is a technically complicated field done by professionals.  I, on the other hand, am some random guy on the internet (though I think that makes one an expert in everything these days). I’m going to discuss my layman’s conservative approach to determining if a bearing is good.  I’m going to define good as “like a brand new bearing” and bad as anything else.  Sure, there’s a spectrum and bearings in between good and bad exist.  I prefer to replace any bearing that I don’t think is good because bearings are relatively cheap, they’re not always easy to get to, and you might forget about the so so ones.


Ball bearings are composed of a few parts made to high precision.  The outer ring of metal is called the outer race and the inner is called the inner race.  Inside all the balls which are held in place by the cage.   On either side may be the shields.  Depending on the type of bearing there may be one or two rows of balls.  Here’s a sampling of some bad ball bearings I’ve replaced.

Ball bearings fall into two categories: Open and “greased for life”.  An open ball bearing has no shields on the sides and no lubrication applied from the factory.  These bearings will have lubrication applied through another means such as an oil bath or greased by the installer.   The “greased for life” ball bearings come with grease from the factory. They also have shields on the sides which try to keep the inside of the bearing clean.  The shields are either metal shields or rubber seals.  The metal shields are a thin piece of metal that blocks off the sides but does not perfectly seal the bearing.  Rubber seals do form a sealed environment which offers better protection.  Bearings typically have the same shield type on each side but don’t always.  Below, in the picture, shows an open bearing (left), metal shielded bearing (center), and a sealed bearing (right).

Good Bearings

To me, a good bearing is one that feels like it just came from a factory.  A new open bearings should spin freely when spun by hand and be perfectly clean.  If you spin it quickly with your finger it should continue spinning and slowly come to a stop.  A shielded bearing should turn with light even resistance and almost immediately come to a stop when spun by hand.  Both should feel absolutely smooth with no gritty or lumpy feeling.  The races should also look good with no chunks missing or discoloration.  The inner race should also not move in any other direction other than spinning in the same plane as the outer race.  Finally, the shields should also look flawless and, in the case of rubber seals, the rubber should still be supple.

I know describing things by feeling is a little suspect.  I’d encourage you to pick a few brand name ball bearings up and play with them.  You’ll soon get a good idea of how they should feel when new.

Bad Bearings

Now I’m going to discuss the signs and symptoms of bad bearings I’ve come across.  Open bearings are subject to contamination from the outside environment before installation and during use if the lubrication isn’t properly maintained.  Dirt and debris can get into the bearings and mess up the precision surfaces inside of the bearing leading to vibration, increased heat, and higher rotating resistance.  Low lubrication levels, the wrong type of lubrication, and water intrusion can also cause trouble for a bearing.  Below is a picture of an old open bearing I took out.  I cleaned it out and left it sitting around out in the open.  As you can see it’s picked up a lot of junk from the environment.

You might guess that the shields on a shielded bearing are important and you’d be right.  While an open bearing is used in a closed environment, shielded bearings are typically left exposed.   Metal shields can become damaged which can reduce their effectiveness at blocking contaminants or cause the shield to rub against the balls inside.

Similarly, ball bearings with rubber seals can have issues with punctures and breakdown due to age.  Older rubber seals become brittle over time and can crack easily.  When I’m checking out seals I like to gently poke them with a flat bladed screwdriver.  The blunt end of the screwdriver should push in on the seal some but the seal should quickly return to normal once the screwdriver is taken away.  I did this test on the bearing below and it cracked and fell apart.

Ball bearings can also be subject to rust.  At some point the bearing below seems to have come in contact with water for a bit leading to the rust.  I’d assume that the amount of water that did this probably made its way inside too.  When I opened this bearing up I saw pitting and discoloration on the inside of the outer race.  The balls inside will roll over the rust breaking it up and wreaking havoc elsewhere inside over time.  Not good.

Remember when I talked aboutgreased for lifebearings?  Well, it should actually be “greased for the life of the bearing” bearings because the life of the bearing may be shorter than the life of your machine.  Grease will break down over time and lose effectiveness.  You can feel this when spinning the bearing by hand.  In some cases you’ll feel lumpiness or grittiness when turning it.  In other cases the bearing will actually spin more freely than a new bearing.  In the picture below I’ve shown a new (cheap) bearing on the left and the bearing from above on the right.  The new bearing has soft clean looking grease.  The one on the right shows dirty looking hardened grease and a lack of grease overall.  When spun by hand this bearing turned freely in between numerous lumpy spots.

I should note that when I say “turn by hand” I mean completely remove the ball bearing from whatever it is in and on.  I’ve found that when a bearing is installed it will feel completely different than when it has been removed.  When installed, problems cannot be as easily felt.  I’ve spun motor rotors and pulleys before and the bearings felt fine.  Yet, when removed felt dry and/or lumpy.  Of course some bearings can be so bad you don’t have to pull them.

Ball bearings can also suffer physical damage from shock loading.  Below is half of the inner race of a wheel bearing that shows deformation from shock aka going over a median.  This damage could be felt and heard.

I’m reusing the picture from up above to talk about the middle bearing.  This bearing is from the back end of the head stock on my wood lathe.  Installed, it felt, sounded, and looked fine.  When I removed it, it felt loose, spun more freely than expected, and the inside race could be moved around (out of plane).   Being at the far end of the headstock I’m sure it had to deal with a lot of shock loading and the saw dust on it tells me some may have made it inside.

This brings me to symptoms of bearing issues that I can’t take a picture of.  Bad bearings can also make noises, cause vibration, and runner hotter.  Bearings can be listened to using a mechanics stethoscope or any kind of solid rod such as a dowel or screw driver.  While in motion place the tip of the stethoscope/rod/screwdriver on the housing that the ball bearing is in near the bearing.  Any rhythmic sounds, sequels, or other irregularities can indicate bearing problems.   I’d recommend listening to multiple bearings to get a good idea what sounds good and what doesn’t.  Bearing temperature can be checked with an IR thermometer gun, thermal imaging, or if it’s bad enough, discoloration.

Bad Bearings?  Who cares?

So, you run across a bearing and it’s questionable.  Maybe its a little gritty or has a small amount of damage.  Should you replace it?  In my opinion yes for several reasons.  The first is that whatever the bearing is in or on is probably several orders of magnitude more expensive than the bearing itself.  The second reason is that you’ve probably already got to where you can access the bearing or have it removed already.  You’ve already done the work.  Just replace it.  The last reason is that most regular ball bearings are super cheap for what they are.  If there’s any doubt in your mind, just replace the bearing.

Also, most of the time a shaft (such as a motor rotor) has bearings on each end.  Replace them in sets.  You don’t want to replace just one and have the other one develop problems in a year or two.  Then you have to do all the disassembly and reassembly again.

Story of Woe

A long time ago when I started this blog, I ran into my first bad bearing issue on the Clausing drill press.  I gave it a once over when I bought it but didn’t find this issue until I was as home.  I grabbed the chuck and discovered I could move it side to side with a soft clunking sound.  Once disassembled, I found that the bottom bearing on the spindle was extremely hard to turn and had worn away the spot on the spindle where it was supposed to sit.  It wore the spindle away so much that the bearing (or a new one) would easily slide along the spot.  Bearing races are extremely hard.  If it’s a battle between a race and most any other steel, the race is going to win.  The picture below shows the bad bearing.  It shows damage to the metal shield from something and even damage to the edge of the race.

This picture shows the spot where the spindle was worn away.  Note that the worn spot is even smaller in diameter than the rest of the spindle shaft.  It must have been this way for a while but no one noticed or cared.

At this point I was left with a drill press that wouldn’t work properly because of a bad spindle.  I looked into several possibilities for fixing the issue.  I could have had the spindle spray welded back up and machined down which may have possibly warped the spindle.  I also called Clausing to see how much a replacement spindle was.  They wanted around $350 for it.  It’s not really unreasonable considering they still supply a part for a 40-50 year old machine but it’s more than I wanted to pay.  Eventually, a used spindle popped up on Ebay for around $120.  I went with the used spindle.  Not a terrible price to get my drill press running but you have to compare it to the $5-$10 ball bearing which caused it.  Technically, whatever/whoever damaged it and neglect cause the issue but you get what I’m saying here.

Finally, ball bearings are cheap but don’t cheap out on bearings.  These days you can have a good name brand bearing shipped to your door for less than $10 from eBay or pick one up from a bearing supply house in your area.  You can also pick up no name super cheap bearings off of ebay. DO NOT DO THIS for any serious use.  If a name brand bearing is $10 and the no name is $3 for 10 something is suspect.  Don’t be a penny wise and a pound foolish!

Anyways, I hope this long winded post will help you gauge the health of your ball bearings and perhaps save you some heartache in the future.


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