New Shop Tool - Old, Obscure Dividing Head

I've needed to create a gear to finish the hand lever collet closer attachment.  This meant I needed a good dividing head (well, I had the small rotary table, and could have done just fine with that one, because a 40 tooth gear is perfectly divisible on a rotary).  I ordered an old dividing head off of eBay. It's time to get it identified.

It appears to be labelled as a "Republic Tools", and the "1161" prefix stamped into the spindle was also stamped into the bottom of the casting (matching numbers... that's a good thing).  It rotates very smoothly, so it's been well cared for.

Typically, a dividing head is a 40:1 ratio, meaning you turn the handle 40 times and the spindle turns once.  This one looks different.  It felt like a 48:1 with the brief check I ran.  I will have to verify this, but it felt less like a 40:1.

The spindle through hole is about 1" (0.923" in the back, probably just an awkward angle and not accurate in any form of the word, and about 1.050" in the front).  There is no real taper on the bore of the spindle, so it's not 3C compatible.  It is definitely not 5C, or a morse taper.   That is going to force me to use the threads for any indexing purposes.

The spindle thread is 1 3/4-8 TPI, so it's an older thread that I might have to build an adapter or a backplate.  I'd like an adapter do I could potentially move from the lathe to this without removing the workpiece from the chuck itself, then things are more likely to be concentric if I need to change machinery between turns.

My brain went immediately to trying the infamous 127 tooth gear so I could potentially cut metric threads on the lathe, and that lead me to check the diameter of the hole plates :

At 4.875" on the outside diameter, if I ran a hole pattern around a 4.5" diameter circle (14.137155" of travel along that diameter) and divided that 127 times, we'd have 0.11131618" between holes along that path.  Seeing as that hole pattern would not have enough material between holes (let's call that "meat"), it could not be a 127 straight-line sequence.  I would have to offset the holes to get a good pattern into at least two rows, but considering 127 is a prime number, it should be three rows (or you end up with two holes on the same path right at the end).  Is that doable?  Absolutely.  I might just have a shop put the holes in the plate for me, though the accuracy isn't as critical for them because I'd be using that to bootstrap another 127 hole plate.  If another shop did it for me via CNC, I'd not need to bootstrap it - it would be accurate enough.  If I do it myself, I would use the index plate to make a second index plate (causing it to be much better in accuracy on the second one at 48 times, if the ratio is 48), and then I'd use the second index plate to create a third index plate.  This would improve the accuracy 48*48, by 2304 times.

Anyway, I need to adapt a chuck to it.  The chuck is a K72-80 (80mm) independent 4 jaw chuck.  I cut a backplate out of some cast iron and bored it to 1.595".

I used a threading tool to cut some basic threads (not big enough), and then used a boring bar at as much of an angle as I could manage to hog out as much thread material as I could.  I grabbed my 1 3/4-8 TPI tap, and man-handled that thing through the bore to get my thread.  This caused the bore and the face to be perfectly aligned (centers even).

While there, I faced it down to match the chuck.  I had to check that the thread was correct, so I spun the dividing head into the thread so I didn't have to re-clock the thread when I removed it..

Successful in the test fit, next up was to identify the bolt hole information so I can drill the holes and mill out relief for the socket head bolts to hold both together.

At 2.25" from bolt to bolt, on a three hole pattern, I could then start some calculations to convert that into usable information.  Frankly, I need the bolt radius.  I started out doing some serious math to determine the diameter/radius.  I spent a half hour doing math using trigonometry before I thought, "Why?"

I ran and grabbed the machinists handbook, looked up the circular segmentation chart, and on a 1" diameter piece of stock, the 3-hole pattern had segments of 0.866025".  Here's where we get tricky.  Because the table listed a diameter of 1, it should be a simple algebraic format :

Segment_Distance

=

Diameter * Segment_Value

Quick flip of terms to reverse what we need (we need the diameter, not the segment length), followed by isolation of terms :

Diameter	=	Segment_Distance
		Segment_Value

Add our values :

2.598	=	2.25
		0.866025

The 2.598, is the diameter of the bolt circle.  The radius (distance from the center) is what I need - to know how far to move it once I have it centered.  Dividing by 2 gives a radius of 1.299".  I grabbed the calipers and set them to 1.299" and lined it up with the center.... viola! That's what I need.

I jigged up the scariest setup of my life on a mill.  It was a matter of using an angle plate (on 1-2-3 blocks to get it tall enough), and a lot of sketchy clamps.  I even had to clamp the back plate to the indexing head (only once it was in position).

I could mill the bolt head pockets, but I could not drill the bolt holes (the mini mill doesn't have quite the work space to use a drill chick and an indexing head on it's side.  Once I had the pockets, I could use a collet to hold a center drill to get those started, and then finished the through holes on the drill press.

Now, it's still too tight to install.  The back plate went into the freezer for a few hours, and the last 20 minutes of the freezer, the chuck went into the oven.  They all came out at the same time.  The different temperatures on the material gave enough expansion/contraction distance that it could be easily bolted together.

With that mated up, I could reverse chuck it into the lathe and face off the back, then add the clearance for the thread.  I first parted it off :

Then I faced it and clearanced the thread :

And finally installed it :

I'd call that a success.  I can now cut the gears (if the table is large enough to hold the dividing head, gear, and tailstock.  I did cut my first gear, but the setup time was extraordinary.  So, I had to change the 4 jaw independent chuck for a three jaw self-centering.  The only one I could find was a 4", and I didn't have a chunk of 4" cast iron for a back plate.  You don't want to try to tap the threads in good steel for a 1 3/4-8 TPI thread.  Trust me, the part just twisted in the jaws.  The only 1 3/4-8 TPI pre-formed back plate is actually much larger - I could only find it for a 6" chuck, so I ordered the 6" back plate.  Here's where things get tricky.

When you attach a chuck to a lathe, you have to machine the backplate on the lathe to maintain concentricity.  It is an absolute must.  In this case, it's going on a dividing head, so if you machine it on a lathe, you will end up with the chuck center line offset from the dividing head center line.  Simply put, you have to machine the backplate on the device it is to be used for.  Have you ever machined a backplate for a dividing head?  No?  Here's what to do.

Taking a 6.25" back plate to be used on a 4" chuck, you need to hog off a lot of material.  Also, I needed about 3/4" of depth, and this back plate is 1.25" deep.  I used the lathe to break down as much of the outside surface as I could.  You must leave it oversized, because you will still machine the plate on the device it will be used on.  So, after the lathe, I'd removed a bit of material.

After removing that, I could put the backplate on the dividing head backwards.  This would allow me to face off the rear surface that mates up against the dividing head.

Once that is surface is machined, I pulled the backplate off and turned it around.  I could then machine the outside edge down to match the chuck.  In this case, the chuck was 3.948", and at this point the back plate was 4.250" in diameter.  I machined off 0.030" using the mill.  You must be careful here.  As the end mill rotates, the direction where it meets the backplate must tighten the backplate instead of loosening.  The speed of the dividing head is minimal, so we don't need to worry much about having it round.  It's nice to do, though, for a finish.

With the outside edge, you can now machine the mating surface for the chuck.  This should be done very slowly - it is the same principle as doing it on a lathe, but the part isn't rotating, and you are taking it off with an end mill.  Remember, when you take off 0.125", it removes twice that because it takes the 0.125" off the other side, so it's really taking 0.250".  Take your time.

After the boss for the chuck has been cut, you can surface the boss so it is deep enough.  At this time, you can rotate the dividing head and drill your holes for mounting the chuck.  I flipped the back plate again, so that the indexing-side surface was on the outside.  This allowed me to bevel the rear flange for clearance on the screw caps.

With that complete, it is now time to pull the plate off and install the chuck.  That completes the installation of a new chuck to a dividing head.

The Pointy Stick Thingey

I was asked to lead some music, specifically, a congregation.  With my background, I needed a baton, and the closest thing I had was a piece of 3/16 stainless steel rod.  I grabbed it and did what I was supposed to do.  When all was said and done, someone was teasing me about my "stick thing" (which was hilarious, because that young lady knows music and what a baton is).

I needed to step up my game.

Today, I ran out to the "shop", and found a chunk of 3/4" round brass rod.  I drilled and tapped the end, then turned the outside down to just over 1/2" (I hit 0.600", not that it really matters), about 1.75" long.  I threw the 3/16" stainless into the chuck next, and turned the tip down, then flipped it and threaded it to match the brass pommel using an 8-32 common thread.  A dab of Loc-tite, and the baton (official term is actually "pointy stick thingey" now) was complete :

Note, the music is copyrighted.

Kennedy Cantilever Toolbox

I found a local guy willing to sell an old cantilever tool box.  I bought it for $50.  It was dinged up a bit, internal paint chipped, and needing some oil.  It seems functional.  Turns out it was a Kennedy 1017-336418 .

I was going to put the fly fishing tying setup into it, but it is a little large.  I might need to just make the right sized tool box for that and use this in another position.

Finally, MQTT Sensor for Home Network

I had been building my own home alarm system a long time ago.  I found that the event server had a memory leak I tried to figure out numerous times, but never succeeded in getting it identified.  It would just get killed randomly on the raspberry pi.  I needed a better interface.

The first iteration was the Arduino with code and a custom TCP connection for alerts.  The server side was the problem here.  This functioned well, but the "server" was a cheap desktop PC that failed because it was on all the time and wasn't designed to.  The PCI bus failed, and it went down.

After the server crash, I then moved it to a raspberry pi to get it online (I didn't care about the PC).  Though it functioned well, it was at this point that a memory leak raised it's ugly head.  I found a number of that I tried to figure out numerous times, but never succeeded in getting it identified.  It would just get killed randomly on the server by the out-of-object memory killer.  (SSH would also get killed, which made it difficult - the process killed was random, and the SSH job dying would force me to pull the plug on it and go through the filesystem scans, HMPH!).

At that point, I switched over to MQTT.  I ran some initial tests using Raspberry PI GPIO's as inputs and Mosquito as the server.  Most seemed to work, but the raspberry Pi would die on me weirdly.  I think the issues with the memory leak were the Linux distribution on the Pi, but it still frustrated me.  Rebooting it forced me to start those processes manually, even though they were in the proper RC files.

At this point, just MQTT (still Mosquito) and a few MQTT translator python scripts was the next move.  It's been going for a while now (with a few power outages) and it fires right up into operational state fairly quickly.  The GPIO's (probably where the kernel had the memory issues) have been offloaded to an Olimex ESP32-PoE device.  It has a simple MQTT plug-in loaded onto it and all it does is check pins and update the MQTT server. I do have one problem where the garage reports errors regularly, so I have to figure out one line (hope a mouse didn't chew through it, or next I'll have to go mouse hunting).

Easy way to a Lathe Tool Holder

I have a cheap Chinesium quick change tool post (the found-everywhere 250-100 AXA clone), and a few tool holders.  I'd wanted a way to keep the tool holders close and organized, but I was frankly too lazy to 3D print something I didn't think would last long.  So, I cheated.

I bought some 1.5" x 0.375" 6061aluminum rectangle bar ($50 for 5').  I tossed it into the Wen angle vise ($75), and then milled the bar at 30 degree angles to get the 60 degrees needed for the tool holders.

I tested them out, and probably should have used bar that was more than 1.5", but it will still work just fine.

The next step is to drill and counter sink the pieces so they can be bolted up to a brace, and then they're done.

Installing a Collet Closer Attachment to a South Bend Heavy 10 (10L) Lathe

I'd been eyeing the collet closers that keep appearing on eBay, and finally pulled the trigger.  On arrival, I realized I had a few issues to work through.  Not having ever used one, I didn't know what I was getting into.  As I played with this puzzle, I realized I was missing a few things, so I asked a great machinist forum (all are welcome there except for folks who push for power or troll everyone else endlessly - it's a welcome forum) - The Hobby Machinist Forum.  The response came back rather quickly.

First, these collet closers include a pin that sticks out of the headstock.  My headstock didn't have that pin.  Most Heavy 10 lathes include a threaded plug that you can pull out and install the pin.  However, I didn't even have that on my headstock.  I had to drill the headstock, tap it, and thread a shop-made pin in.

Second, I was missing the gear.  Yeah, in case you didn't know, the outboard gear on a heavy 10 lathe (the one driving the reverse tumbler mechanism) is not the same for collet attachments.  That one sticks out a little bit to engage a woodruff key in the attachment itself.

Third, the good collet closer attachments have a Gits oiler on top to keep the brass bearings for the clutch handle lubricated.  Mine didn't have that.  It means I'd have to replace the threaded pin holding it on up top with a new one that had a hole through it and an oiler.

First was handling the pin in the headstock.  This is easiest (and doesn't get cast iron chips into the machinery) if you remove it from the lathe and dismantle it.  Once ready, you need to center punch where you will drill, then do the normal.  The procedure is documented on the hobby machinist thread where I originally asked those questions.

If you look in that last picture, you'll see my lathe's live center in the quill.  It allowed me to keep the tap centered along the axis of the hole I'd just drilled.  However, it should be noted that you don't want to do this if your live center doesn't have a tang to help remove it when you are done.  It's a serious pain to remove if you don't pay attention to this.  I first tried holding things at an angle into the quill, different keys, and even prying on things I shouldn't.  I finally gave up, grabbed one of my ball joint separator forks, shoved it around the live center taper, gave it a couple of small whacks with a hammer, and it came loose.  Again, please don't ask me how I know not to do this.  It's a painful memory that has repeated itself twice.  [sheesh].  Don't forget to counterbore the hole.

Well, with that ready, I had to make the pin.  It's pretty simple,  Again, dimensions come from that hobby machinist thread I'd mentioned earlier.

Install the pin, drop that arm over it, then bolt the arm up to the closer handle, and this piece is done!

I also had to create the set screw/Gits oiler combination.

Next was to get the gear.  I'd watched eBay for a while after knowing I needed one, but never found one.  It's an 18DP, 40 tooth gear that sticks out 1.4" farther than the standard gear.  This was a bit of a surprise to me because the other gears (for the banjo and the change gears) are all 16DP.

I bought a chunk of iron, and bored it out, then turned the outside down.

This gave me the gear blank.  I still need to face the outboard end of the gear and clean it up a touch, but then I need to cut the actual gear teeth.

Tools to Make Tools

I've been wanting a tubing bender.  So, I downloaded plans from the chopper builders handbook website (a JD2 clone), ordered some stock, and started making it.  In the middle, I realized I needed to bend some flat stock on a hard angle for the handle.  So, my tool quest turned into a second tool quest.  This tool, my "brake attachment" for the harbor freight shop press, is made from :

• 1" angle iron about 16" long (4 pieces)
• A flat bar stock that will fit two pieces of angle iron wide
• A flat bar stock to hold the upper piece of angle iron
• 7/8" tool steel dowels about 5" long (two of them) for guide pins

First, I cut the edges on two of the pieces of angle iron so they could be welded site by side to the bottom plate.  I then welded the second piece of angle iron to the other two inverted.  This gave me an inverted 90-degree channel offset by 45 - exactly what I needed.

I then drilled and tapped at 3/4-16 the two ends of the bottom plate, turned down the two dowels to 3/4", and then threaded them to 3/4-16" to fit the bottom plate.  This was my first foray into power tapping.  Can you do it on a harbor freight mini mill?  Yes, but you want the tapping head.  Collets are a bad idea - you'll ruin your collets when it galls from spinning.  This got it started, and I was able to hand finish the tapping.

I punched two matching holes into the top plate to loosely fit the two dowels.

Lastly, I need to weld the last piece of angle to the top bar with everything in place so that it all lines up perfectly.