Friday, January 17, 2014

Steady Rest Redux, and some misadventures

I really started out to make a feed screw for the Taig lathe. Really I did. What I have found out about this machining business is that to make A, you have to first make B. However, that entails making C and D and so on, so sometimes you lose track of where you are.

I actually did make a feed screw. It was a 1/4"-20 RGU feed screw, approx. M6x1. It was far too flimsy.  I knew it had worked for Dean over on (look under "feed screw for the Taig lathe") but I found it very wobbly. So I needed a bigger screw. I am limited by ready availability, so maybe M10x1 would do it. Not for sale at Home Depot. Maybe 3/8"-16? This is about M10x0.75. But, here comes the problem, I cannot get a 3/8 screw through the bore of a Taig, so ... we need a steady rest. I made one before, see label "steadyrest", but it is too flimsy, just like the 6mm feedscrew. 

I had used a wood-turning attachment as the base of the old steady. It worked. But not really steady enough for what I want. So first I have to make the slide. This is a 45 degree dovetail slide, about 7mm on perpendiculars. So I set out to make the slide.

I had some 1/2" (12+mm) steel so I traced the outline of the old slide onto the new stock. Then I had to mill it out. And now we come to making C. I wanted to use my new Christmas present, a 4mm endmill. The bigger the endmill, the less work. But Cecil B. de Mille cannot chuck a 4mm bit.The biggest chuck is 3.2 mm or 1/8" RGU.
Now you cannot possibly turn down a 4mm mill shank down to 3.2 mm, even with carbide tools. The stuff is much too hard. But you can grind it down. So I mounted my trusty Dremel on the cross-slide. The adapter you have seen before, it is part of a chainsaw sharpening attachment. It ate the grinding wheel to a nub, but it worked. Sort of. Alas, I had a taper on it. It is very difficult to get the Dremel exactly parallel to axis of lathe. I finally set up a dial indicator.

I am getting far too much runout. (Off-center error), 0.1mm or so.  I actually did grind it down to 3.2 mm at base, but it tends to squeeze out of the chuck. Disaster. Time for another plan. 
I set up the vertical milling attachment on the Taig and put a really big (12mm) bit in the chuck. This is a no-no. You are not supposed to do this. I did it anyway and it worked.  So I "hogged out" most of of the slide by this method. I must say it was a pleasure to take really big cuts. By my standards anyway. So now we can clean up on Cecil. I put the bar right on the table and held it down with toe clamps, just like the big boys on YouTube.

The next job is to cut the 45 deg slots for the dovetail. The big boys use dovetail cutters. I haven't one; and it would never fit in my mill anyway, so we improvise. Using a protractor we tilt the piece to 45 deg and mill straight down.
Here you see the first dovetail cut. I am setting up for the second. Tomorrow, all deities willing, I will start cutting it. Then I can worry about the rest of the steady rest. Then I can worry about the feed screw. Whay did I ever take up machining? Because, in the end, it is fun. Getting to the end may not be so much fun, and is sometimes very frustrating. Life, after all. 

Thursday, January 9, 2014

Chain Mail, the coda

So we come to the end of the chain mail saga. I have made enough rings to go around the earth, or so it seems. One last thing to make. It is only fortunate that the recipient does not read my blog. She is much too busy! This number is a fine-mesh, 3/8" or about 10 mm as opposed to my usual 13mm rings. It is harder to do the small rings than the big ones. I have tried 6mm rings and I consider it almost impossible.

 As usual it is a pendant plus a chain. All in 4:1 mail, which means that each center ring links four side rings.

In this piece, the center rings are copper -- salvaged electrical wire -- and the others are steel, 14 gauge fencing wire. Very cheap stuff. I like the contrast. There are two pieces. the pendant and the chain to go around the neck. Here is the pendant. I like the contrast of copper and steel. Picture has a slight yellow cast to it. Sorry. Blame auto-exposure.
 The chain is single-strand 4:1 chain mail. If you were making this for protection you would not use copper, you would use all steel. But I'm making it for decoration. I want it to look nice; protection is merely symbolic.
The wire at the top of the pendant is there to stiffen it up. It does tend to sag, but I think I will remove the wire and just put in two more linking rings into the top.

And I am now really through with chain mail. If disaster comes and we all revert to the middle ages, at least I could make a living as an armorer. Although by now I am quite deft at this, it is very labor-intensive. But then, another word for the middle ages is labor-intensive. No machinery allowed. Glad I did it, but enough is enough. Now back to other things, such as my clock.