Saturday, April 29, 2017

Pickle Jar

I had a proof-of-concept at one point for bleeding brakes on the car.  It was a simple design, based on a large bulk jar of pickles.  I had drilled two holes in the lid, and used teflon tape and brass fittings to seal the jar.  Then, one of the lines is run to the brake zerk fitting on the brake calipers.  The other line was connected to a vacuum source.  This allowed me to connect it, start the vacuum, open the zerk, and then simply top off the fluid at the master cylinder until I had fluid in the jar.  Functioned pretty good, until I loaned it to someone who broke the jar.  He got me a new jar, but I thought I'd make a better lid for it.

I ordered two things - a chunk of 4.25" aluminum round cut-off, and a rotary table (needed to cut the bayonets in the lid so it would lock down).  I turned it oversized according to the dimensions from the existing lid, drilled a through hole it (so I could thread in a rod and hold it up (hang it).

I then marked a groove (for concentric attachments, drilled 120-degree-apart holes, then tapped them with a pipe thread.  That allowed me to simply thread in the brass pipe inserts.

The hardest part was putting the bayonets on the bottom lip.  There were six of them, so I HAD to have a rotary indexing table.

First, I used a boring bar to cut it to a solid lip on that bottom inside edge.  Next, I had to mill out between the bayonets.  This is what required the rotary table.  I threw a collet into the spindle with an end-mill, positioned it for a cut, then simply milled the lip off to get a bayonet.

Then I assembled it into a functional brake bleeder :

While I was at it, I had a neighbor who needed a thumb screw for a photography gimble.  So, I cut two of them :

Now I can get back to work on the corvette!

Friday, April 21, 2017

South Bend Junior - How To Set Up For Screw Cutting

I have a problem.  My lathe came without quite a few parts.  I've purchased change gears, and those change gears came with a thick idler gear :

(It's the one on the left.)  You can see the gear used to transfer to the lead screw on the upper right.  Obviously, the one on the left won't fit to the small teeth on the gear on the right, so I ordered an 80-tooth one from eBay.  It arrived, and it, too, wouldn't fit :

I don't have one of those forking banjos, either :

I was not sure how I was supposed to set these up, so I looked up the gearing for cutting an 18-pitch thread :

I needed a 32-tooth gear on the stud and a 72-tooth gear on the lead screw.  I reversed the screw gear and bushing so it would line up with the large gear on the idler (the same one connecting to the stud gear).  This turned it from a compound gearing to an idler gear.

Next, I chucked up a small chunk of cheap aluminum, because scoring from a tool cutter would show up easily, and it was soft enough I could rotate the chuck by hand.  Then, I turned it a few times to get enough for a thread pitch gauge :

And measured it :

18 on the pitch!  Success!  Next, cut some actual threads.  Again, I started with aluminum.

Next, I threw on my 25/64 bar I needed for a custom tap (yes, I had to learn all of this for a tap, which was for a stupid brass pen).

I removed it from the chuck and used a dremel to cut some relief in it (some of the reliefs I cut backwards, so beware if you make a tap), heated it up red-hot, and quenched it.  I didn't care how hard it really was, because it had a single purpose - to cut some threads in a plastic insert to finish a brass pen :

For anyone who doesn't know about South Bend Juniors, that's how screw cutting is set up!

Saturday, April 1, 2017

A Beautiful Spring Day in the Shop

Today, I finally had some time to spend out in the shop.  So, I tackled a few projects.  I have a neighbor who is a machinist, and a few days ago, he caught me and asked if I'd be interested in any of his cut-offs.  So, I ran over today to go pick them up :

In that pile of great stuff was some 303 and 304 stainless, brass, bronze, aluminum, steel, and even some Delrin.  I had a colleague asking if I'd be able to machine him some shock pistons for his RC cars.  They are supposedly 12mm across, with a 1.6mm hole in the middle.  I measured it up and threw down a quick drawing :

So, that 12mm is actually 11.80mm, or 0.465".  That hole in the middle which should be 1.6mm is actually 2.54mm, or 0.10".  It means I have some really good leeway when it comes to machining them.  I chucked up some Delrin, and cut five pistons (because one was a little too think).  They didn't turn out too badly!

Next up, I dropped the starter.  I needed to know how large of a fly wheel I have on the Corvette.  I couldn't find the receipt, so I had to do it.  But, I was having problems turning the crankshaft and also counting teeth while I was at it.  I remembered I had an old Harbor Freight composite camera system, so I grabbed the camera, build a frame to hold it, and placed it pointing at the hole through the scatter shield where the starter connects to the fly wheel.  That allowed me to count teeth :

I have a 168-tooth flywheel. I ordered a 2.5HP adjustable starter from eBay, so when it comes, I'll get it installed and running.  Then, I thought I'd finish a brass pen while I was at it.  It came out not too badly :

It was a good day today!