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Speaker Crossover

Posted by davidjbod on May 23, 2015

Over 10 years ago I made a center channel speaker for my home theater sound system.  “Home Theater” is over selling it a bit but it was my center channel speaker.  I made it from some scrap plywood my dad had I think along with some 4″ woofers and a tweeter that Radio Shack was clearancing out.  The tweeter came with a capacitor attached to it to filter out low frequencies which I considered good enough for a crossover at the time.  I assembled it and used it for several years.  Eventually, we moved and the center channel got shelved as we were using the TV’s speakers.

A couple weeks ago we decided to move the TV into one of the spare bedrooms and create a game room.  I grabbed a surround sound receiver a friend had given me and decided to pull out the center channel again.  Here’s a pic of the speaker as it sits now.

Co1

At some point some kids (not mine) had poked in and ripped the old tweeter as you can see below.  I picked up the one you see above from Parts Express and fit it to the cabinet.  Note that the old tweeter had four screws holding it on while the new has three.  This and the larger back of the tweeter required modifying the cabinet a little bit.

Co1a

Before I get into making the cross over, I should probably explain what a crossover is.  As I’m sure you know, speaker drivers (the actual transducer not the box) reproduce sound.  They do this by moving in and out at a specific frequency to reproduce a specific tone.  Put a lot of movement together and you get music or the spoken word.  There are numerous types of drivers.  Some are made for very low frequencies known as subwoofers.  Some for low frequencies called woofers, higher up the frequency spectrum comes midrange drivers, and at the top of the spectrum are tweeters.  This leaves out some but covers it for the most part.  Drivers work best when they’re reproducing the frequencies they were designed for.  Trying to make a driver produce other frequencies can result in poor, quiet, or no sound at these frequencies.  In the case of tweeters, passing them the high power signal that should go to the woofers can burn them up.  Some speakers, typically poor ones, have one driver.  Others have two, three or more driver.  A speaker with two different drivers is typically known as a two way system.  A three way system has three different drivers.  In a two way speaker there’s a driver for producing lows/midrange and one for producing highs.  A three way splits up the work even more.

This is where the crossover comes in.  The crossover filters out certain frequencies for each driver letting pass what’s best for that driver.  My center channel is a two way speaker despite having two woofers.  They’re the same and in this design the two woofers correct an audio issue I won’t bore you with.  In a two way crossover, frequencies below a certain point get sent to the woofer(s) and those above the point get sent to the tweeter(s).  Once again, I’m glossing over details, but thats the basic idea.  For my speaker I set the crossover frequency at 2000 Hz.  I found a website that calculates the values of the required electrical components to filter the signal.

When crossovers filter a signal they don’t just chop everything else off.  Instead, they slowly decrease the signal outside of the bounds.  The rate at which they decrease the signal is known as the crossover order.  The crossover I chose attenuates the signal at 12 dB/octave.  The crossover frequency is actually the frequency at which the signal has been attenuated by 3 db.  If the crossover is designed correctly the two drivers will complement each other and there won’t be a noticeable frequency range that is attenuated around the crossover frequency.   I don’t feel like putting the effort into verifying this for my speaker though.  So, I’ll just cross my fingers and be ok if everything isn’t perfect.

With the theory out of the way, we can turn to the actual crossover.  The calculator asks for the impedance of the drivers and the crossover frequency desired.  With this information, it generates a diagram with some capacitors and inductors and the value of each.  Each capacitor/inductor combination will filter the signal for a speaker or speakers depending on how it’s wired.  The picture below shows the diagram of the crossover and the parts I’ll make it out of.  In the diagram the signal comes in from the left and gets spit up into the crossover components.  The signal is routed up towards the tweeter and to the right to the woofer passing through the cross over components first.  Capacitors let high frequencies pass and inductors let low frequencies pass when wired in series with a driver.  That’s the role of the C1 and L2 components in the diagram below.    Without L1 and C2 I’d have a first order cross over but the addition of these components results in a second order crossover.

Co2

One of the fun parts of electrical work is figuring out how to actually wire things together.  The diagram has lines connecting all the components that you might think of as wires.  In reality there doesn’t have to be any wire and you can connect the parts together directly.  To figure it out, I first laid all the parts out on a piece of wood I’d build the crossover on.  Then I made all the connections to assemble the crossover taking time to triple check the connections.  Here’s what it looks like on it’s own.  The capacitors are the black cylinders and the inductors are the wound copper loops.

Co3

Happy with how it looked, I pulled out the hot glue gun and stuck the components to the wooden base.  This keeps everything from rattling around in the speaker cabinet and putting strain on the wires.

Co4

Next, I added all the leads and soldered it all together.  I hooked up all the speakers and checked the resistance value of the crossover at the input leads.  All I wanted to check was that there wasn’t a short.  A multimeter checks resistance with DC which you can think of as a 0 Hz signal.  So, this signal is blocked by the capacitor from the tweeter and passed trough the inductor to my two woofers.  I got a reading of around 4 ohms which makes sense for my two woofers wired in parallel.  With this check and a final review of the whole circuit I hooked it up to a small amp.  I ran music through it for a bit and everything seemed to be working well.

Co5

Next, I clipped the extra leads off of the components and taped them up with electrical tape.  Not pretty, but who cares.  No one else will ever see it…other than you of course.  Finally, I glued it in the bottom of the cabinet, stuffed my fiberfill back in and put it all back together.

Co6

 

Hooray sound.  But not good sound.  Something is off but what.  I put my ear close to each speaker and as expected heard lows out of the woofers and highs out of the tweeter.  For some reason though the speaker sounded odd like it was missing some lows and like there was re-verb when listening to voices.  Music sounded like it was missing the lows as well.  After a little bit, I decided to place a book over one of the woofers with some music playing.  The lows instantly came back and I knew what had happened.  I swapped the book to block the other woofer to confirm and heard the same results.  Somehow, one of the woofers was out of phase and canceling out some of the sound from the other woofer.  If you remember your wave theory, two waves that have peaks and valleys that occur at the same time are said to be in phase.  When you combine them they add together.  If they are out of phase a little bit then the frequency can shift.  If the waves are opposite, known as 180 degrees out of phase, they will cancel each other completely.   This is what my woofers were doing.  They didn’t cancel completely of course but they were fighting each other.

I pulled the woofers to see what was going on and realized how I’d messed up.  I reused the leads with the crimped on connectors that I’d made years ago.  The woofers have a large and small tab for the positive and negative terminal respectively.   When I went to wire the driver leads up I only looked at the stripe on the wire sets to determine polarity.  I’d put the wrong connectors on of the woofer back then and had never fixed it.  I suppose that when I’d wired it up years ago I hooked the wires up intentionally backwards instead of recrimping the connectors since I didn’t have the odd sound before.  Anyways, I changed out connectors and put everything back together correctly this time.  Much better!  Low and midrange frequencies were back.

Speaking of phase, here’s another note.  In a second order crossover system one part of the crossover will lag by 90 degrees while the other will lead by 90 degrees.  This results in a phase difference of 180 degrees.  To correct for this, I wired the tweeter “backwards” so that it will be in phase with the woofers.

 

PS – I picked up an old Sony Cybershot camera at a thrift store for $10 and tried it out on this post.  I don’t think it’ll replace the D50 though.  So, no bounce flash like normal this time.

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Replacement Focusing Knob

Posted by davidjbod on May 17, 2015

I have an old Bushnell spotting scope that I bought a while back.  Overall, it is in good condition.  One of the problems is that the focusing knob has been cracked from tightening down the set screw that holds it on.  As a result, it slips on the shaft and you cannot adjust the focus reliably.  Time to fire up the lathe.

FN1

I took some measurements and sketched out a rough drawing to work from.  Basically, it is a cylinder with a stepped hole in the middle and a threaded hole normal to the center axis where the set screw goes.

FN1a

I decided a steel 1″ knob would be a little overkill.  Instead, I chose to use some aluminum I’d recently ordered.  This is the first aluminum project I’ve done on my lathe.

FN2

The original knob was a little over 1″ but 1″ is the largest piece of aluminum I have.  The outer diameter isn’t a critical dimension though.  I took a light pass to clean up the surface. I was very happy with the surface finish I got from the old girl.

FN3

Next, I put a slight bevel on the bottom of the knob.  I did the same to the top after removing a little material.

FN4

To increase grip on the knob I wanted to put a knurl on it.  I only have one size knurl with my quick change tool post which made selecting the size of the knurl easy.  I slowed the lathe down, fed the knurling tool in, and engaged the feed to move it to the top of the knob.  The knurl didn’t come out perfect though as the final spot I knurled is slightly different than the rest.  I’m not sure why.  Knurling takes a bit of practice.

FN5

Moving on, I removed the live center from the tail stock and used the chuck to drill the small hole that the focusing shaft will go into.

FN6

Next, I removed the small drill bit and drilled the larger hole to fit the spotting scope.

FN7

To drill the perpendicular hole for the set screw, I removed the bar of aluminum and headed over to the drill press.  I then drilled and tapped the 8-32 hole for the set screw.

FN8

Before I’d removed the part from the lathe, I turned my tool post to bevel the edge of the large hole I’d drilled in the bottom.  Before I can part off the knob I need to align the tool post to be perpendicular to the work.  This is important for the cutoff operation.  If the cutoff tool isn’t perpendicular to the part then the sides of the tool will rub the work which can result in a poor finish and possibly break the tool.  (Technically, the cutoff tool has to be aligned with the direction it is being fed in.  Since I’m feeding in with the crossfeed it needs to be perpendicular.)

FN9

I parted the knob off, filed down the post left on the top of the part, and sanded the top down to 600 grit to leave a nice brushed finish look on the knob.  I thought this was a good alternative since I couldn’t think of a way to hold the knob to clean up the top of it.  After that, I put the knob back on the scope and can now focus without issue.

FN10

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Making a T-Bolt for the Hendey Lathe

Posted by davidjbod on December 6, 2014

In the process of grinding the jaws on my lathe, I tightened down one of the compound bolts…but it never got tight.  Hmm.  I looked at it carefully and noticed the nut and stud were both turning.  Not good.  I disassembled the compound and found one of the T bolts had broken.  I pulled the bolts out and found one had sheared apart.  It turns out that this wasn’t an original bolt.  Someone had made it by welding a stud to a small plate.

HT1

As you can imagine, I need a replacement T bolt and you can’t just pick up a replacement part.  Luckily, Gill offered the use of his lovely Monarch 10EE to make a new one.  I ordered some 1″ 1144 steel to make the bolt and headed down to his house once the steel had arrived.  I cut off a piece to use and mounted it to the lathe to being work which first involved facing the piece.

HT2

The T bolt uses a 7/16″ – 14 tpi thread.  To cut the thread on the new bolt the diameter of the piece was brought down to the major diameter of the thread.  behind the section to be threaded, the bolt was brought down to the minor diameter so that the tool would have a place to stop after making a pass to cut the threads.  Without this area, the cutter would cut a V shaped groove into the part when the carriage stopped moving.

HT3

Cutting the threads required making several passes advancing the compound each time.  After demoing how it worked, Gill turned the threading operation over to me.  After a small error at the beginning of the first pass, cutting the threads went well.  In the picture below you can see the results of the threading operation.  In this pic, I’m about to reduce the diameter of the T, which explains the cutter.

HT4

Once I was happy with the part, it was parted off and rechucked to clean up the opposite side of the T bolt.

HT5

Here’s a pic of the new bolt fresh off the lathe compared to the original T bolt.  The original T bolt has a kidney bean shaped head.  So, there’s a little more work to do.

HT6

To shape the head, I painted the bottom of the bolt, held both bolts back to back, and scribed the correct shape on my new bolt.  I set to work using a file to shape the bolt after putting it in my vise with Aluminum jaws in place.  I used couple coarse files to remove most of the material and then finished the edges with some smooth files.

HT7

Here’s the final part compared to the original.

HT8

With the new bolt in place, it’s time to make chips again.  I’ve added a green arrow to show where the bolt goes.  They’re loosened and tightened to rotate the compound.

HT9

Making the T bolt I learned a couple things.  First, 1144 steel machines very nicely on Gill’s lathe with carbide and on mine with HSS.  I even got a good surface finish with a regular cutting tool profile.  Second,  you have to be quick when threading. Threading involves the carriage moving pretty quickly.  When the tool exits the area you’re threading you’ve got to disengage the carriage feed before the tool hit the work piece.  Third, quick change tool posts are wonderful.  Being able to just drop the tool in place and go without setting the height is great.  Finally,  Gill’s lathe is very nice.  Well, that last one was just reaffirmed.

 

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Hendey Finishing Touches: Jaw Grinding

Posted by davidjbod on November 28, 2014

I decided to address another problem with my Hendey lathe.  This time I turned my attention to my three jaw chuck.  My chuck had two issues I wanted to address.  The first is that it would not hold a part perfectly centered which is known as runout.  Runout is measured by holding a ground bar in the chuck and placing a dial indicator to measure the surface.  The spindle is turned through a complete revolution and the maximum and minimum values noted.  The difference of these values is the runout.  It’s easier to set the dial indicator to zero at the low point and then find the high spot.  I measured 0.008″ runout with a 1.25″ diameter ground rod.

JG2

The second issue with the chuck was that the jaws were wider at the front of the chuck than the back.  I’ve seen this referred to as being “bell mouthed”.  This is easy to see because you can see light between the part and the jaws.  To illustrate this I’ve slipped a 0.006″ feeler gauge between one of the jaws and the part.  It goes in about 0.25″ and thinner gauges went in further.

JG1

To fix these problems the jaws are ground on the lathe.  As there is slack in the jaws, they must be forced outward to take out this slack.  I used a method I came across on Home Metal Shop Club‘s website.  The author of the article suggested using shims to push the jaws apart as opposed to the more commonly seen ring.  Using my friend Gill’s Bridgeport, I made a set of 1.25″ shims.  In the picture below, you can see I’ve also marked the jaw faces with Dykem to monitor progress on the jaws.

JG3

Professional machine shops and well equipped hobbyists use tool post grinder for grinding the jaws.  It is setup to be mounted in the tool post to easily attach it to the lathe.  I lack such a tool and instead used the arrangement you see in the picture below.  It’s a pneumatic die grinder that I’ve “attached” to the tool post.  Though it looks rather shoddy it held the grinder tightly enough for what needed to be done.

JG4

I don’t have any pictures of the actual grinding because I wanted to focus on that.  First, I covered my lathe as best I could to keep out grinding dust.  Grinding is done with both the lathe and grinder spinning.  I ran my lathe at ~100 rpm during grinding after trying several slower speeds first.  To start the actual grinding, I advanced the grinding wheel to the back of the jaw until it contacted to locate my zero.  I dialed out 0.002″ with the cross slide and slowly moved the grinder out with the feed wheel.  From here I kept advancing the grinder out and making passes checking my progress frequently.  At first I was only contacting one jaw but eventually all three were being ground.  As expected, in the beginning the area ground was in the back of the jaws.  As work progressed the ground area moved outward.  Once I was happy with the results, I moved the grinder in, dialed out another thousandth, and made a pass out of the jaws.  I figured that this would impart a slight taper into the jaws which would be wider at the back since the grinding stone wears as the pass is made.

Seen below is a picture of the results.  Note that my shims now have a concave edge on them.  Before I started grinding I noticed they would get hit first by the grinder.  I pulled them off and ground them on my bench grinder.  The jaws all showed an evenly ground area everywhere except at the very tips.  The tips were banged up and I didn’t want to remove the material required to get the last little bit ground.

JG5

While I was set up for grinding, I figured I’d touch up the front face of my jaws.  As you can see below, the front faces of my jaws near the middle are a little dinged up.

JG6

I made passes with the grinder taking a couple thousandths off each time until most of the front face was cleaned up.

JG7

Once I was done grinding, I wiped all the surfaces of the lathe down to remove any grinding dust.  I also removed my chuck, disassembled it, and gave it a cleaning as well.  I put it back on the lathe and proceeded to take another measurement of the runout to see if there was improvement.  I was rewarded with a runout a small bit over 0.003″.  I’ve seen this runout specified on some new chucks.  So, I was pleased with my results.

JG9

The “bell mouth” was also gone.  I couldn’t see any light between the chuck jaws and the part.

JG8

If you’re wondering why I don’t have zero runout, there are a few reasons.  The first is that inside of the chuck is a large scroll which also wears some over time during operation.  The jaws ride different portions of the scroll depending on how wide open the jaws are.  Thus, the area the jaws were pressed against on the scroll when I ground the jaws is not the same as when the jaws are at some other position.  Since the scroll has probably worn unevenly, even if my jaws were perfectly ground in one position you can’t say that they would be perfect in another position.  This also means, that my ~0.003″ runout measurement is only at that one diameter.  I measured runout with a ground 0.25″ rod and had less than 0.001″ runout.  Another reason would be my grinding set up.

I’m happy with the improvements I’ve seen in my chuck.  I’m not sure how old the chuck is but I imagine it is quite old.  I’m glad to keep running it with the lathe.  Even if my runout had not decreased the removal of the “bell mouthing” will result in a better grip on the work piece.  I’m hoping this will translate into an easier time parting off on the lathe.

Unfortunately, while tightening down one of the locking nuts on the compound, I broke one of the T bolts.  It looks like someone had fabricated it from a stud by welding a piece of steel on top of it.  So, I will be fabricating a replacement T bolt in a future post.  For that, I’ll be taking a field trip to Gill’s.

 

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Jack Repair

Posted by davidjbod on November 15, 2014

I was doing some automotive work last weekend when the release mechanism on my jack broke.  I had jacked the car up and placed jack stands under it.  When I went to lower the jack, which requires twisting the handle, there was a little bit of resistance and then the handle spun freely.  Hmm, not good.  I used another jack to free my broke jack and was able to get the car safely back on jack stands.  I inspected my jack and found that the universal joint had broken.  My jack is an aluminum Craftsman jack and they felt like saving an ounce by making the U joint out of aluminum as well.  This doesn’t seem like the best decision in my mind.  Anyways, seen below is my broken universal joint.  The square end on the left fits inside of the jack handle and rotates the valve on the right side of the pic.  The U joint has two pins of different sizes and the body piece that the larger pin went through broke.  I looked online but Craftsman didn’t offer a replacement part that didn’t involve buying the cylinder.  Guess I’ll make a replacement part.

JR1

To start I chucked up a piece of 3/4″ steel rod into the lathe to drill a hole through it.  Before drilling, I used a center point to start the hole.

JR2

Next, I drilled to an appropriate depth with the lathe.

JR3

I cleaned up the surface with a few light cuts to eliminate the mill scale.  The original part was 3/4″ diameter.  So, my part will be a little smaller but made of a stronger material.

JR4

Here’s my piece once I’d parted it off the lathe.

JR5

From this point, making the part will require drilling three holes through the part.  Two holes are for pins and the other hole is to remove a large amount of material to form the U.  I used my height gauge (Thanks Gill!) and some Dykem to scribe the location of the holes.  I also used a small machinist square to scribe a vertical line to align the two pin holes.  Finally, I lightly punched the hole locations to keep my drill bit from wandering.

JR6

Here’s the point I’d use a mill…if I had one.  Since I don’t, it was off to the drill press that did a good job.  I oriented the part as best I could under the drill bit and proceeded to drill the two pin holes.  JR7

I rotated the pin 90 degrees and drilled out what would be the bottom of the U shape.  After drilling I noticed that this hole wasn’t exactly 90 deg from the two pin holes.  This was unfortunate, but not bad enough to trash the piece.

JR8

I held the piece in the vise and used a hack saw to remove the material between the large drilled hole and the end.  Then, I used a file to round over the edges and clean up the inside of the part so that the cross journal block would fit.

JR9

I dressed the ends of the pins I’d removed and then reassembled the universal joint with my arbor press.  Once I was satisfied with how everything fit I peened the ends of the pins to keep them in place.

JR10

I reinstalled the part back into the jack, bled it, and gave it a couple test releases.  Success!

JR11

Now back to putting the transmission back in the car.

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Hendey Finishing Touches: Part 1

Posted by davidjbod on November 10, 2014

As expected, as I’ve been using my lathe, I’ve run into some issues.  The first issue I mentioned in my last post.  During drilling with the tail stock, the spindle would seize in the conical bearings.  My Hendey employs two conical bearings for the spindle to run on.  The face of the front bearing runs against a spacer that presses against a flange on the spindle.  Over time this spacer and the bearings will wear.  As a result the spindle can contact the bearings instead of riding on a cushion of oil.  Shims can be added to the spacer (or a new spacer made) to maintain the correct spacing between the bearing and spindle.  Thanks to the folks at Practical Machinist I knew why I was having this issue and expected to run into it.

The first thing I had to do was get the back plate off the threaded nose of the spindle.  To do this I removed the chuck from the adapter plate.  The adapter plate is held on with three screws with recessed hexes.  Unfortunately, the screws had somehow been damaged to the point where I couldn’t remove them with a hex key.  I ended up drilling out the heads enough to where I could remove them with a screw extractor.

H140

With the adapter plate removed, I had access to the back plate.  Though I’d tried to get this off before, I was able to finally.  After seeing the idea in a post on Practical Machinist, I wedged a tapered piece of wood under the bull gear to immobilize the spindle.  Then, with a piece of mild steel and a hammer, I struck the shoulder of the cut outs on the back plate.  After a hand full of moderate blows the back plate broke loose and I breathed a sigh of relief.

H141

Here’s the nose of the spindle.  It looks to be in great shape.

H142

From posts on Practical Machinist, I was able to determine what size shim for the spindle was required.  The method to determine the proper spacing first requires you to remove the spindle, wipe the oil from the spindle and bearings.  Then, remove the stock spacer and reinsert the spindle using firm hand pressure to seat it.  Next, measure the spacing between the front of the bearing and the inside of the spindle’s flange.  For my lathe the space was 0.129″.

H143

Next, you need to measure your spacer, as I’m doing in the picture below, and subtract this from the gap size. Then add about 0.006″.  I say about because there was a small range I saw discussed and this was in the middle.   The 0.006″ provides the correct spacing for the bearings.  Doing the math says I needed a 0.011″ shim.

H144

I ordered some 0.012″ shim stock from McMaster and went to visit my friend Gill to cut it out on his Bridgeport.  Try as we might, we were not successful.  In the end, I picked up a piece of 0.01″ thick brass locally which we were able to successfully cut.  I didn’t get a picture of the shim because my camera was dead but you can see it installed in the picture below.  Brass will probably wear faster than if I’d used steel but I think it will last a long while under the light use it’ll see from me.

H145

Once I had the shim taken care of, I reinstalled the chuck.  To replace the screws I had to drill out, I bought some from the store and then turned the heads down to fit on Gill’s superb Monarch lathe.

Next up, is the issue of the rear bearing leaking oil profusely.  As the machine is running oil is picked up by a ring and carried onto the spindle.  It then runs out both ends of the bearing into a flanged section of the bearing and then back into the reservoir via a small hole.  As you can see below, a piece of the flange was broken before I got the machine which lets the oil leak out.

H146

To take this back to factory would require making a new bearing which is something I’d like to avoid right now.  Instead, I cut a piece of flashing and formed it to the shape required.  It is held in place with a metal band clamp.  The back side of the flashing was covered with a thin coating of RTV sealant before putting it on to keep it from leaking at the edges.

H147

With the guards back in place the bandage on the rear bearing doesn’t stand out that much.

H148

The last thing I did was to replace the key in the tail stock.  The original one had been worn and allowed the tail stock spindle to rotate slightly under load.  This key fit tightly into the tail stock and took some filing to fit correctly.

H149

Once the lathe was back together, I tried drilling steel with a 1/2″ drill bit like I’d done previously.  This time the drilling went well and produced some nice chips.  Yay!

H150

Now I can get back to making stuff on the lathe.

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Hendey Assembly: Part 5

Posted by davidjbod on October 15, 2014

In my previous post on the lathe, I’d reached the point where the lathe was running.  I still had a few more things to do though.  When I’d started on the lathe I set the tail stock aside since it is pretty much a separate item.  It came apart easily as it was covered in gunk like the rest of the lathe.

H130

I ran all the parts through the parts washer and then hit them with a wire wheel/cup.  The parts were cleaned and then painted.   I hit all of the shiny parts with a buffing wheel and they cleaned up nicely.  I reassembled the tail stock and noticed that the spindle didn’t move in and out easily.  I removed the main screw and mounted it between centers on my woodworking lathe.  Using a dial indicated I determined that there was about 0.03″ run out on the shaft.  To fix this, I took the screw over to my arbor press and straightened it.  After one iteration the screw showed 0.005″ of run out which allowed the tail stock spindle to move freely.

H131

Here it is back on the lathe.  Luckily, the tail stock spindle has a #3 Morse taper instead of the hybrid Morse-Hendey taper I feared it might have.  The #3 Morse taper is a standard size and arbors can easily be purchased today.H132

I removed the motor and the motor mount I fabbed up.  I added a simple metal electrical box to cover the cord to motor wire connection.  I then used double sided tape to hold the box in place in case I decide to remove it later.   I also painted the motor mount black to match the rest of the lathe.

H133

While I had the motor off I replaced the motor pulley.  The old motor pulley is poorly made and allowed the belt to slip excessively.  I replaced it with the gray pulley which works much better.  Shown below, are both pulleys for comparison.  I removed the old pulley before reinstalling the motor.

H134

With the combination of V belt pulleys, the countershaft turns at 266 rpm.  After taking measurements of the cone pulley diameters I should have spindle speeds of approximately 93, 193, 368, and 761 rpm.   I measured the actual spindle rpm unloaded at 97, 193, 351, and 678 rpm.  There seems to be a little slippage on the upper two speed values.  I’m not sure what it slipping but I’d place my money on the V belt.  Additional tension may solve this but I think the slippage can be attributed to the combination of really large and small pulleys.  The belt doesn’t get a lot of contact with the small pulley since the wrap angle is small.

The first project I completed on my lathe was to turn some plugs for the two spindle oil holes in the head stock.  I patterned my replacement plugs after the original ones on Chris’ lathe.  They have a ball on top which flares out to a rim and then reduces to a cylinder.  You can see them in the picture below the front and back tie bar contact points.

H135

Here’s a few pictures of the finished lathe.

H136 H137 H138

Overall, I feel the lathe works pretty well.  There’s some backlash in the movements but that’s probably not surprising given that the lathe is around 100 years old.  The nuts for the cross slide and compound are brass and I imagine they have worn instead of the screws.  As such, I could probably make new nuts in the future.  I may also make new half nuts as the threads show a lot of wear as well.  There’s also some tightening in the cross slide as I move it in and out due to wear but so far it isn’t problematic.  One of the gears on the side of the late is made of brass and seems a little loose on its shaft.  When running it tends to make a ringing noise.  At some point, I’d like to bore this gear out some and make a new shaft for it to run up.

Here are a couple videos of the lathe in operation. In the first video, I’m taking a light cut on some hot rolled 3/4″ steel. I’m also showing the automatic stop feature.

In this video I’m taking a little heavier cut.

 

 

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Hendey Assembly: Part 3

Posted by davidjbod on September 21, 2014

After weekends of traveling and retrieving Chris’ lathe, I was finally able to get back to working on my own lathe.  While I was visiting my parents, my dad and I took a trip over to a friend of his who owns Goode Machine Works.  They were able to fix the motor support arm that was cracked.  I also got a tour of the facility where I was able to drool over the numerous cool machines they have!  A 400 ton shear is an impressive machine.  Here’s a couple pics of their handiwork.  Best I can tell they heated it up and used Nickel rod to make the repair.

H100 H101

I proceeded to grind down the welds and prime the arm in preparation of painting it.  I left the serial on it so someone can be confused about it like I am in the future.

H102

The chain drive “tank” took a trip through the parts washer and was then painted as well.  On my machine, it only supports one end of the countershaft as it had been gutted previously.

H103

The support arm, bracket, and tensioning mechanism received the same treatment.  They were hung to dry on my fancy drying rack.

H104

When the lathe fell, the lid on top of the chain drive “tank” took damage.   A chunk popped out of the side and the lid was cracked from there, through the hole, and almost to the other edge.  I decided to see if I could weld it up.  I’m happy to say it turned out successfully!  Since the lid is cast iron, which is tricky to weld, I was concerned.  I ground the crack out with a carbide burr and then welded it with some Nomacast rods since I didn’t need to do any machining on it.  I ran short beads and peened them with a needle scaler while it was cooling as I’d read to do online.  I don’t think anyone would mistake it for the work of a skilled welder, but after a little filler I don’t think anyone will notice.

H105

I turned my attention to the counter shaft which held the upper cone pulley.  Once I got it apart, I discovered that the pulley shown in the center of the picture below is wooden.  There were also several broken screws and a drill bit in it for some reason.

H106

This is the other half of the cone pulley.  As expected it is cast iron.  For several reasons, I don’t think this is the factory setup on the lathe.

H107

I reattached the arm and brush painted it in place.  It was simpler than trying to hang it some place and spray it.  The cylindrical bar at the top of the arm is actually backwards in this pic.

H108

I turned the bar around and started adding parts back on.  The folks at Goode said that it wasn’t worth fixing the broken motor mount given how badly it was broken.  I also realized that it was broken and missing some parts before I got the lathe.  I’m going to fab something up to support the motor later on.

H109

I used the wood lathe to clean up the upper cone pulley.  This section has a fair amount scoring and the smaller pulley shown below has an odd wear pattern on it.

H110

 

Here’s the wooden pulley.  It also has some scoring but cleaned up well.  I re-profiled it a little bit to put a slight hump in the middle of the pulley.

 

H111

I’m currently waiting on paint to dry on some parts but it is definitely getting closer to running.

 

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Hendey Lathe Assembly: Part 2

Posted by davidjbod on August 22, 2014

Work continues on the lathe….

I used my woodworking lathe to clean up the lower cone pulley and the back gears shaft.  I made an arbor out of wood to mount the pieces and then worked on them at my lathe’s lowest speed.  It made the work much easier.  You can see the difference in the clean and rusty sections below.

H80

I cleaned the gear box gears one by one with a wire wheel.  Overall the gears appeared to be in great shape as there were no missing or deformed teeth.

H81

I cleaned up the smooth bars using a wire wheel but the lead screw was a lot more trouble.  I capped off the end of a 1-1/4″ PVC pipe to soak the lead screw in parts cleaner solution.  It dried out the grease on the lead screw but I still had to clean every thread with a Dremel wire wheel.  But once it was done I was able to reinstall the gears and lead screw into the gear box.  The gear box and bars were then reinstalled on the machine.  Somehow I managed to miss the end of the reverse rod but I cleaned it up after the pic.

H82

Next up was putting all the gears back on.  This went pretty smoothly since I’d numbered everything and took plenty of pics.H83

The carriage was dunked in the parts cleaner and then hit with the wire wheel.  This was followed up with a little bit of paint.

H84

I reassembled the apron and carriage next in preparation of reinstalling them.  After that was finished, I put the carriage back on the lathe, installed the plates which keep it from lifting, and put the apron back on.H86

It’s beginning to look like a lathe again!

H85

One of the things I broke when the lathe fell was a threaded rod in the taper attachment.  I’m not 100% sure what the rod does but it has to be replaced.   I ended up drilling through the rod and using a square ease out to remove the broken section.H87

I figured I’d clean up the chuck while I was cleaning everything else up.  The inside of the chuck is pretty well sealed and was clean inside.  It went to the regualr cleaning progress.  Once everything was clean I oiled, greased, and reassembled the chuck.

H88

Brass plates look nice but are time consuming to clean up. Best I can tell there’s no easy way of cleaning them.  I soaked the plate and the scrubbed it with a soft bristled brush.  Judicious scrubbing cleaned most of it up but some of the corners required the use of a dental pic.  Eventually I got it cleaned up and then used some some Brasso on it.  Much better.

H89

I got the back brass ring on the head stock fixed (it’s threads were messed up in a spot) and then reinstalled the spindle.  With it in place, the back gears and the rest of the gear train was reinstalled.  After that, covers were reinstalled.

H91

The last touch on the “main” part of the lathe was reinstalling the brass plate. Big difference from when I originally got it.

H92

At this point I could do some turning if I had an overhead line shaft.   Since I don’t, next will come repairing and cleaning up the motor arm components and tailstock.

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Hendy Lathe Assembly: Part 1

Posted by davidjbod on August 3, 2014

In my last Hendey post I’d finally reached the point where I’d taken the lathe completely apart with the exception of the tail stock.  Now comes the repetitive task of cleaning and painting.

The handles, knobs, and dials were originally polished steel or brass.  I cleaned them up with a Dremel and buffing wheel.  One of the handles below has had its pin replaced with a bolt and nut.  Once I get the lathe up and running I’ll fix this.

H60

I picked up a parts washer off of Craigslist and it has been great for cleaning the smaller parts.  The parts were tossed in and left overnight.  After they’d dried, the grease was converted to a chalky gray substance that was easier to remove than trying to wipe off all the grease.  I used a variety of wire brushes for cleaning.  Where I could, I used a wire cup on an angle grinder.  Any spots I couldn’t reach with the grinder were cleaned using a 3/4″ wire brush on a pneumatic die grinder and if needed a wire wheel on the Dremel.  I ordered a large lot of wire wheels for my Dremel off of eBay for much less than you find them in the store.  They seem to shed a little more than the name brand ones but at the cost I was ok with it.  Below is a picture of the compound in the middle of being cleaned with the wire cup.  It works well and is fast.

H61

Once the parts were cleaned, I wiped them down with paint thinner until the rag didn’t pick up any dirt (or close to it). Next, most of the parts were primed but some of the gears were left bare and then painted.   I hand painted some parts but spray painted what I could.  The brackets could be easily masked but the gears were easier to hand paint.

H62

The body casting of the lathe is held on to the intermediate legs by six bolts.  With them removed, the casting can be separated for cleaning.  I tried pressure washing it but it wasn’t very effective.  After a bit of time with the grinders I was able to get it ready to paint.  No more straps here.  The lifting setup has a significantly higher working load limit than the engine crane.

H63

The main legs and pan were cleaned and primed with self etching primer.

H64

The pan required a little bit of masking off with tape.

H65The body casting required significantly more masking.

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For the most part I didn’t worry about filling imperfections.  I don’t mind mold texture on the castings or the occasional flaws.  It is a tool not a Corvette.  That being said, it looked like someone had taken a grinding wheel to the outer gearbox cover.  So, I used a little filler here and there.  I should mention that I used some dental picks in cleaning as well.  They’re great for scraping crud out if tight corners.  I got a large amount of them from my father in law.  Check to see if your dentist is tossing some out and you may luck out.

H67

The brass plate with the gear chart on it was held on with brass nails that had been peened over.  I drilled them out to remove the plate.

H69

Here’s the completed compound.  I polished up the dial and handle and adjusted it as best I could.

H66

The apron has a bunch of parts but most of them don’t require paint.  I painted the inside of the apron because it was there.  I doubt anyone would notice if they saw the machine.

H70

For the most part the apron didn’t have any issues.  The first was that someone had replaced the set screw on the half nut lever with a bolt that they ground flush.  I drilled it out and taped it for a 1/4″ set screw.  The second issue was a pain.  Show below is the longitudinal feed mechanism.  The shaft on the bottom goes inside of the assembly with the gears.  The large wheel fits on the assembly and a knob screws onto the end of the shaft on the bottom.  Tightening the knob causes the carriage to be driven longitudinally by the lead screw.  In the past someone had hit the hand wheel bending the entire thing.  The end of the hollow shaft was egg shaped which required a little bit of hammering and drilling to fix.  The shaft for the knob required a little filing, polishing, and numerous test fits to correct.  Finally, the knob tightened and loosened with a light constant drag.  H71

I discovered that modeling clay can be used to cover small holes and the Gits oil cups.  It hardens after a day and pops off cleanly.  I used if several times to help mask off the head stock.H72

The legs and pan were primed and hand painted by brush separately before being reassembled.  I primed the body casting and then dropped it back on the stand as it held it well for painting.  H73

More later!

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