Saturday, May 27, 2017

Making a Gear Cutter Arbor

I had some gear cutters for cutting some 16DP gears.  It was another break I needed away from placing a lot of stupid gears on a piece of paper to get them laid out.  I did not have a way to use them.  So, here is my stab at cutting an arbor down to size, drilling, and tapping the hole.

Now, I can potentially grab a slab of aluminum round large enough for the gear, true it up, then throw it on my rotary table and make custom gears (127 teeth and 100 tooth gears will be needed for a perfect metric thread base).

Truing a Chuck Back Plate

While preparing to create a tap in my last post, and still needing a break from that Cocoa Table project, I needed to put on a new, small chuck.  My two chucks I already had were either a 4-jaw chuck (takes a long time to get the work close), and a 3-jaw chuck that only had outside jaws.  I had ordered a small 3-jaw/4" chuck, and it had arrived.  So, it was time to get it mounted up.

  1. Install the back plate to the lathe, NOT to the chuck.
  2. Once it's on the lathe, use some tooling to face it off, and cut the shoulder you need for the chuck to fit.
  3. Now you can remove the back plate from the lathe and install the chuck to it.
  4. Once done, it is ready to use.
Yes, it is really that simple.  It was a quick task when I had just a little time to spend on it.

Creating a TAP

Hello, I needed to take a break from laying out so many little tiny gears on my dads Cocoa Table Project, and I did need to redo one of my brass pens.  In order to do that, I had to create a tap to cut some internal threads (15/64" 18 threads per inch).  I had a chunk of 1/2" tool steel from building a tramming tool in Calibrating a Drill Press, so I decided to use that.  It was a matter of chucking it up, turn down a section of that to 0.24" (15/64 is 0.235", but I wanted some space after the threads were cut).  Then, throw on the gears for threading, and cut some 18-TPI threads.

At that point, all you have is a screw or bolt.  For a tap to work, you need to cut some relief to allow the material somewhere to go.  I used a Dremel with a cutoff wheel to put in a leading cutting edge, then some stones to put some good relief in there.  I also cut two sides parallel so I could use a wrench to get a grip on it, then heated it up and gave it a good dunking to get it hard.  Worked great!

Friday, May 12, 2017

Calibrating a Drill Press

Remember that second-hand drill press I found that was made in Taiwan?  It was a little rough around the edges.  I had even checked the quill and replaced the bearings and chuck (that little South Bend chuck was worth every penny).  Well, as I've been trying to set up the tooling for building that table for my dad, I knew I needed to make sure the drill press table was level.  If it is not, you never get 90-degree holes.

In order to get it level, you have to "tram" it.  "Tram" is short for "trammel", which is a tool used to calibrate machinery.  A good trammel will give you measurements within 0.0005" - but I don't have that kind of dial indicator, nor will I unless it is a donation.  But, I needed a trammel.

I had seen a video on youtube (by Dale from Metal Tips and Tricks) on making one.  His was gorgeous, but I just needed it to work.  I ordered 1"x1" aluminum stock about 12" long, and a 1/2" chunk of drill rod, and two cheap dial indicators from Harbor Freight.  Do they have to be right on?  No, because it's a relational measurement that you are after anyway.

Once all of the parts arrived, it took me an evening of work to get the block drilled, cut, tapped, and the drill rod cut and faced, then the whole thing assembled (and to learn how to merge videos, convert them upload them and post).  Not a bad job.  Here's my new trial run at doing this - a video on youtube.

The above video was taken using a cheap Chinese "GoPro" knockoff, an SJ7000.  The camera does have its limitations (it won't do high-speed video work), but it is perfect for throwing a $40 camera into the shop and recording 1080 video (not fake 1080p resolution, the real 1920x1080x30FPS) without fear of destroying it or soaking it in cutting fluid or oil.  It's not bad, but I made the video even worse by having light behind everything - it washed it all out, but the video still came out okay (definitely not professional quality because of the way I did things).  Here's the final "product" :

With that, I threw it into the drill press and measured the table.

Forward-aft is pretty accurate (actually 0.005" off - which is phenomenal for a drill press).  Side-to-side was not so good.  It was 0.200" high on the right, and 0.200" low on the left.  That was actually amazing in itself, as all I have to do is loosen the bolt that allows it to tilt, twist the table, and re-tighten.  I'll do that on Saturday, and I should be able to drill some pretty accurate holes!