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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Posted in Metalworking, Projects, Repair, Restoration, Tools | 3 Comments

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.

Parts

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.

 

Posted in Repair, Restoration, Tools | 1 Comment

Removing Broken Bolts

I spent the last month working on my car and got to deal with a couple broken bolts/studs.

The first one I had to remove was a stud from an exhaust manifold that broke off in the head.  I put a wrench on the nut, gently tried to turn it, and it fell off.  I’m guessing it was damaged before I touched it.  This stud broke off a little bit below the surface.  Unfortunately, the side of the head is angled down and I wasn’t able to see it clearly.  Below you can see the broken stud in the mirror.

I decided to drill it and try to use an extractor on it.  Due to the location there was no way to position a center punch or be assured I was drilling in the middle of the stud.  To help myself out, I came up with a few simple drill guides made from bolts.  I made them by holding one in the lathe, facing the end to get rid of the taper, and then drilling through the bolt.  In my case I wanted to remove the taper from the end of the bolt so that I could screw it into the little bit of thread available.  I recommend making multiple guides and drilling them to final size with the bits you will be using on the broken bolt.

Once deburred, I was able to screw the guide in on top of the broken bolt.  With it in place I could start drilling.  As a commentor reminded me, it is advisable to use left handed drill bits for this.  Sometimes the broken part is loose and the left handed drill bit will grab it and spin it out.  Once I reached the desired depth, I removed the first guide, and put in the larger one.  Then I was able to try out the extractor but the bolt wouldn’t budge (And I was deathly afraid of breaking the extractor).  Eventually, I gave up on the extractors and just drilled the entire bolt out, picked the bits out of the threads of the hole, and chased it with a tap.  Due to the accuracy of the hole I initially drilled, I was able to drill to just over the minor diameter of the stud’s threads.

If you unfortunately, find yourself in a similar situation I recommend making one of these guides.  Though I used a lathe, I believe the guides could be made on a drill press.

By far my favorite method for removing broken bolts is the “weld a nut to it” approach.  For this method you center a nut or washer over the broken bolt and weld the two together.  If you start with a washer, you’ll need to weld a nut to it.  After it cools you can gently try to remove the broken stud.  If the nut breaks off, weld another on and keep trying.  Ideally, use an impact wrench on the weakest setting to remove it.  Once it starts to move you’re home free!

This technique works well because the heat of welding helps to break the rust bond and the nut welded on gives you something to grip.

My exhaust manifolds have thin metal heat shield on them held on by small 6mm studs.  They were rusted pretty heavily and broke when I tried to remove them (I should have heated them).   I was able to remove the broken studs quickly with this method.  Just try not to partially melt the nut like I did.

Tada!

Of course the best way to remove a broken bolt is not to break it in the first place.  To avoid this, try rocking the bolt forward and backward, an impact wrench, using penetrant, or heat.

Posted in Repair | 2 Comments

100W LED Flashlight

I was wasting time on Youtube when I came across a video where someone had made a flaslight with a 100W LED.  I was curious how much they were and went to eBay to check.  It turns out they’re pretty cheap at around $8 shipped.  So, of course, I had to make one.  I can’t claim credit for anything new as I’m using similar parts to the folks on Youtube but it was fun to make.

The 100W LED is rated for 3 Amps at 30-35V.  It also puts off a bunch of heat which requires a heat sink.  I could make something but there are ready made heatsinks with fans for this LED on ebay already.  You also need a reflector and lens to focus the light beam.  In the pic below you can see the 100W LED mounted to the heat sink with the lens sitting off to the left.  For reference, I’ve also put in the smaller 10W LED I used on the Wheel Horse.

LEDs require a specific current which means I’ll need a way to supply it.  I also decided I’d use a power tool battery and boost the voltage up to the 30-35 volts needed.  I went back to eBay and found a DC to DC boost converter with adjustable voltage and current capability.  You can see the boost converter in the picture below.  The two blue potentiometers are used to adjust the voltage and current.

Before I built anything I rigged up the fancy testing apparatus shown below.  I picked up a cheap 18V rechargeable lithium drill battery from Harbor Freight to use as my power source.  It’s only 1.3Ah but it came with its own charger.  Importantly, it was also the cheapest option I could find.  To set up the converter, I first adjusted the output voltage to 30V before hooking up the LED.  Then I turned the current potentiometer down and hooked the LED up with my multimeter inline to measure the current.  Turning the LED away from myself, I turned it on and adjusted the current and voltage to give 100W.   Then I took it outside and lit up the world.The LED was bright but I wanted to get a tighter beam out of it.  So, with the current turned down, I messed with the positioning of the lens.  I was never able to get to really narrow the beam though.  I eventually sat down on the computer and did some lens ray tracing to see if I could figure out how to get the beam tighter.  Eventually, I realized that with this size lens and emitter there’s really no way to get a tighter beam.

While I was fiddling with the lens I started using my welding helmet to avoid seeing squares because it’s bright even when dimmed.  I snagged a picture of it at full power through the welding glass for you to see.

After I was done prototyping, I sketched out a few design ideas.  I ended up deciding on a triangular aluminum frame.  The first step was to mount the emitter/heatsink/fan.  I drilled and tapped some holes in the heat sink, turned some standoffs, and mounted it to the bottom rails.

Next, I closed off the end and put the battery in place temporarily.  I came up with a cross piece which links the two sides, attach the handle, and hold the panel.  I also decided I wanted to be able to adjust the brightness of the flashlight while using it.  To do that, I removed the current potentiometer and wired in a bigger potentiometer with a knob that I could easily adjust.  The potentiometer allows me to vary the LED current from 0.4 to 3 amps.  With the structure temporarily assembled, I wired it up again for some more testing.  The resistor sticking up, it just there temporarily to drop the voltage for the 12V fan while I was waiting on a voltage regulator to arrive.  Also, this battery pack doesn’t have a low voltage cutoff, so I’ve added a small display to keep track of the pack voltage.

Once I was happy with it, I disassembled the frame, smoothed the edges, and reassembled it with “proper” wiring.  I also found I needed a glare shield to keep from shining light at myself when using it.  Here’s another view.  I’ve packed the voltage regulator for the fan in between the battery and end of the frame and the voltage gauge onto the battery pack.  Here’s the business end.And the display.Here’s a couple pictures of the flashlight in action.  The camera settings are the same in both images.  On the left is the flash light at the low mode.  On the right is high.  High is pretty bright.

Clearly, I’m not going to get great run time with the flashlight on high.  In fact, I only got about 10 minutes until the voltage meter hit 15V and I shut it down.  At low though, I expect to get over an hour though I haven’t tested it.  Either way its great for when you need to light up an entire yard or signal a UFO!

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Headlights for the Wheel Horse

I went ahead and added LED headlights to my Wheel Horse garden tractor.  The incandescent bubs that were in it would have drawn more amps that the engine’s electrical system produces.  This would result in the battery being drained by the head lights.  To fix this I replaced them with some 10W LED’s I picked up off of ebay.  Together they’ll both draw a little under 2 amps form the electrical system which will leave some to charge the battery.  I’m sure the LED’s are much brighter than the OEM bulbs too.

Below is a pic of the area where the headlights sat.  Previously, there were two circular bulbs that were held in with a tab and bolt.

I used a scrap piece of 1/8″ thick aluminum to hold my LED emitters.  The aluminum will also serve as a heat sink to keep the LEDs from burning up.  I drilled and tapped holes in the plate to hold the emitters and brackets for the lens and reflector.This is a picture of the reflector that goes between the lens and emitter.  It’s made of plastic which is an insulator.  It is important to note that the reflective coating on it does conduct electricity though.  It’s not a dead short like metal would be but I did measure about 11 ohms between one side and the other.

On some other LEDs I’ve got from Ebay the reflectors fit on the white plastic part of the emitter.  On the 10W LEDs the reflector contacts the tabs for the wires that power it.  To insulate the reflector from the wires I used a bit of electrical tape.

Unlike the incandescent lamps, I can’t just hook 12V up to these LEDs even though they’re rated for 12V.  LED’s need a constant current and these require 1 A apiece.  To provide that, I found a simple constant current circuit online.  This circuit only requires two transistors and two resistors.  One of the resistors is used to set the current of the LED.  I assembled the circuit and blobbed some silicone on it.  It’s hackish and I’m sure I’ll be reassembling it at some point.

I temporarily wired everything up and turned the lights on.  They’re pretty darn bright. To give me the option of dimming them some I added an additional switch to the dash which picks between two different valued resistors in the circuit.  The up position on the switch runs the lights a 100% and the down position runs them at 25% current.    They’re still bright in the lower setting but there’s a definite increase switching to “high beams”.   The original light switch still turns them on and off.

Here’s a picture of the new headlights in position.

Finally, here’s a shot at full brightness in the dark.  It lights up with width of my yard, across the street, and a little into the neighbors yard.

So, yay mobile flashlight!

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Small Trailer Resto

I picked up a small trailer to go with the Wheel Horse last year off of Craigslist for cheap.  After I picked it up, I built a tailgate for it but have used it as is since then. It’s seen better day and I finally got around to fixing it back up.  I’m not sure who originally made the trailer but its got 17 cu ft of volume.

As you can see, it’s got some rust and flaking paint on it. OK, mostly rust.

The trailer must have sat front down for a while and collected wet leaves. This caused the heavy rusting in that area.This view is from the inside and backlit to show the rust holes in the bed.  This is a tipper trailer and the front support for the bed is in this area.  Eventually, it would push through the weakened area. After disassembly, I worked on removing all the old paint and rust.  This was easily the worst part of the resto.  I hate removing paint. Once it was mostly clean, I cut out the rusted area to weld some replacement pieces in.Welding in the replacement panels was tougher than I thought it’d be.  Though I’d removed the area where the rust had eaten completely through, there were still a lot of spots where it had partially eaten the metal.   This resulted in the welder burning though in spots and generally being a pain.  Eventually, I got the replacement pieces welded in.The next step was to start painting it.  First, I laid down a coat of primer.

Next, came the paint.  I figured IH red and black would match the Wheel Horse. I also painted the wheels and put new tires on.  I’m getting faster and changing these annoying small tires.

Yay! Finally done with it.

Here it is in use picking up pine straw. 

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Replacement Prentiss Vise Nut

Recently, a reader commented that he had a Prentiss vise with a broken vise nut.  He asked if I knew of how to find a replacement.  I said recommended a few places but said he’d probably have to have one made.  He replied that he had approached several machine shops but none would accept the job.  This isn’t too surprising given what’s involved in making a replacement.  You would either need to single point cut the thread or buy a tap to make the internal threads.  I decided to offer to make the nut for him and he accepted.

He sent me a picture of his broken vise nut. After a few emails back and forth I realized that my Prentiss vise has the same nut which would make reproducing it much easier.   The original nut is made out of cast iron but the new one will be made out of steel.   Cast iron has better wear properties but the vise won’t be seeing a lot of use so it doesn’t matter in this case.

Here’s a picture of my vise nut to show what I’m trying to make. 

The first step in copying the nut was to determine what thread the vise uses.  After some measurements and research I determined that it’s a truncated 7/8″ diameter 3-1/2 TPI 10 deg modified square thread.   This isn’t something you’re going to be able to find a tap for off the shelf.  You’d have to have one custom made as I’m sure the factory did.

I determined that the easiest approach would be to single point cut the thread.  This required grinding an appropriate tool bit.  Though I could use my vise lead screw to test the fit on the nut, its length would require moving the carriage to the end of the lathe each time.  Instead, I decided to make a shorter plug that also let me test cutting the thread.  As I cut the thread on the plug I tested the fit with my vise nut until I got the fit desired.

Here’s a short video showing part of a pass.

Yay, it fits!

I also tested cutting the internal thread into a piece of aluminum.  Using aluminum meant that the machining would take less time than steel.  I learned a great deal cutting the test piece.  Cutting the internal thread took longer than the thread on the plug because the boring bar I used tended to chatter and flex.  I eventually got it done though.  Now on to the steel.

The first step in making the steel nut was to remove some of the material on the front side.  I could have done it after cutting the thread but having less thread to cut was a big positive.

I started by drilling a hole and boring it to the correct size. 

Cutting this thread was slow for several reasons.  This first is due to my lathe.  The carriage doesn’t immediately stop when the feed is disengaged due to momentum in the gear train.  This requires me to run the RPM slowly (about 90 rpm) so I don’t crash the lathe.   The second is due to tool pressure and boring bar flex which required very light passes of about 0.002″ in steel.  This internal thread has a height of about 0.1″.  That’s a lot of slow passes.

I started cutting the thread but ran into an issue where I couldn’t cut the thread any deeper due to the bar flexing.  Since the thread is almost square, a large side force is generated on the boring bar while cutting which causes it to bend.  At a certain depth I could not longer advance the bit into the work.  To deal with this, I made another tool bit that cut a thread with more of a V shape.  This thread shape created less force on the boring bar allowing me to cut the thread to depth.

Next, I went back to my original tool bit and cut the entire thread again.  Since some of the metal had already been removed there was now less force on the boring bar and I was able to get the thread finished.  Once I was near the final depth, I used my test plug to get my desired loose fit.  I didn’t want to make the fit tight because the plug is based off my vise’s lead screw which may have some wear.

Here’s a view showing the internal thread.

Eventually, I moved the carriage to the end of the lathe and tried the actual lead screw.

Once done on the lathe, it was time to remove the extra material from the nut. (That’s a cool smoke trail from a chip!)

Then some grinding and flap disc work.

Finally, I could test fit the nut in my vise and verify it worked.

After this, I got the the nut into the mail and crossed my fingers that it would fit the commenter’s vise.  I know it should but I was still concerned.  Happily, it did fit!  I’m happy to have helped someone out but can firmly say I have no desire to make another one of these.

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