Lathe

This page is merely a journal to keep track of my metalworking adventures. If I keep on working on it, something good may come out of it. If not, it'll die - big deal.
I think I just found a good supplier of small quantities of metal at reasonable prices. As I write this, I am going to submit my first order, and will reflect on their service later, once I have some experience with them.Update The experience was good, except they didn't have the order ready the following morning, as they say on the website. Well, to their credit, they used the word usually, so I can't complain about driving to Fremont in vain - it was my fault for not checking. Also, they lost my drill rod, and I didn't notice when I picked up my order. So, I am missing one piece. That would be their fault for messing up the order and my fault for not checking.
18 Dec. 2003 I've just took a first shot at machining titanium. Before trying, I made sure to try and learn as much as I could about the metal, as well as any tips and tricks about cutting it. It really wasn't as bad as a lot of people seem to say. However, I did have to regrid my HSS toolbit a few times - titanium seems to weld to the tip of the toolbit and breaks it off. I tried different speeds, feeds, even tried reducing the relief angle on my toolbit to offer more support - to no avail. I remembered that people suggested using copous amount of coolant, and, indeed copious amount does help. In fact, that was the only thing that would extend the life of my toolbit beyond a single cut. It is interesting to note, however, that, when drilling, my drill bits do not seem to experience the same welding problem. I used progressively larger drill bits, from 1/8" to 1/2" and, while running hot, none of them had any traces of wear after use. Is that because they are TiN coated? Is that because the cavity drilled constantly had a small pool of tapping fluid in it? Would carbide tools weld less? I guess, I probably should ask all those questions on the newsgroup. Meanwhile, here's the result (a Ti ring for my wife, to be presented around valentine's day).

30 Dec. 2003 Being unemployed has its advantages, I guess. Since I now have some free time, I decided to undertake a fairly large (at least for me) project - add a leadscrew to the lathe. I think, I have done more than half of it today, and hopefully have just one day of work left.
30 Dec. 2003 Beeing cheap as I am, I didn't bother buying a die holder when I bought the lathe. Nick strongly suggested I do so; I refused. Well, he knew better, but I was on a budget. After cutting the first couple of threads I realized that I really need a die holder. So, here's my fairly crude version of a die holder after cutting a nice long thread in brass.

1 Dec. 2003 A lot of things have changed since the last update. To name a few, I've lost my job and I have visited the Boeing Surplus Center, which is a treasure trove for some things. Among other things, I've made a simple version of a rotary table. Nothing fancy, but it allowed me to make this cam by milling it out of a chunk 6061 Al with a 3/8" end mill.

It was a bit of a hassle to make the cam because it is a bit larger than the largest piece I can mill using a milling attachment, but, as you can see, things have worked out OK. In the end, the cam turned out to be quite good - the arcs are milled within about .005" of the specs and all other dimensions are within .002". Besides the rotary table, I also ended up making some more tools to make this project work. In particular, I needed a couple of end mill holders, which can be nicely made out of blank arbors (I made two - 1/2" and 3/8")

and in order to make those, I had to make a really small and long boring bar that would allow me to bore holes smaller than 3/8" (in fact, the smallest it can do is just over 1/4" diameter at about 2" depth). Sounds very flimsy, but it did bore out the blank arbors with no complaints, so, I guess taig's tool steel is better that I imagined (not that I really knew what to expect - it just looked awfully thin when I was grinding it, and I had that nagging feeling that it would flex a lot and eventually snap when grinding steel).

14 Nov. 2003 Well, it looks like my fears about the bearing being defective were unfounded. I just wiped off the grease, as Nicholas has suggested, and have been running happily for quite a few hours, with no more grease seeping, and no apparent problems. So far, I only have made a small mounting fixture that allows to mount a dial caliper off the depth stop, so now I can accurately measure the position of the carriage on the slide. (I've toyed with a few other ideas, but all of them resulted either in the DI being in the way, or the setup being too flimsy). I've snapped a picture, but I left the camera at home, so I'll post it later. I have already used it and found immensely useful. I've also learned that I don't know jack about milling. I wonder if there's a 'milling for dummies' or something similar to help my ignorance. So far, I have learned a bit about feed rates, surface cutting speeds, and seem to be able to make much better cuts than before, but I still have lots to learn. Currently I need to address the problem of chips piling up in narrow cuts and meling together resulting in a porous aluminum mess. Unfortunately, I do not have an air compressor to help with that problem. But I do have an old vacuum cleaner that might do the job - we'll see.
3 Nov. 2003 For my first project with the lathe, I've fixed a watch bracelet.. Also, I discovered something disturbing - after running the lathe for just a few minutes (maybe 15 or so), I noticed lubricant seeping out of the headstock bearing. I don't know if this is normal (e.g. first time you run the lathe, the bearing warms up and squeezes extra lubricant out) or not. I made sure to follow directions that said how tightly to tighten the headstock to the bed, so it is not over-tight. I do not know how much of a tension there should be on the belt, but, since taig recommendsthe 1/4 HP motor leaning on it with half its weight, I assume tension in the range of 7-8 lbs should be acceptable. The tension on my belt is not more than that. Lastly, the headstock doesn't feel too warm, and rotates freely, quietly and with no noticeable run-out. Everything seems perfect, except fo the seeping lubricant. I guess, I'll join the yahoo groups and ask people there. Here's how it looks:
3 Nov. 2003 I've got my motor today! Unfortunately, I realized that I don't have a switch that would survive very long turning this motor on and off - 1/2 HP motors seem to draw a lot of current when first turned on. Now, I could've figured that out if I used my brain earlier... Oh, well... For now I am just using a switch on a surge protector, which is a really bad idea, but it'll survive till tomorrow, and I'll come up with a better solution then.Here's how my setup looks like:
Yes, it is a bicycle handle you see hanging over the headstock pulley. My garage is really small, and I have to fit a car in there! The bike is hanging off the ceiling by its wheels, and there is another one on the other side of the garage over my drill press and grinder. Someday I'll buy a house and have a REAL garage. I hope.
30 Oct. 2003 Today two things happened.
  • First, I got a tap and die set, which is the poorest quality set I've ever seen in my life. It was also the cheapest, so I can't complain. Some of the smaller taps are unusable at all, and some dies will need some fiddling with a needle file to make them cut decent threads. Oh, well... I've got some set, and will buy more taps and dies individually as needed.
  • Second, I've learned that my motor won't arrive till next monday (3 Nov), but I can't wait that long to see my lathe in action. The only suitable motor I could find happened in my old thrift-store purchased drill. It does about 1300 RPM, so it works nicely.

    Unfortunately, the drill chuck is too small to grab a 1/2" rod that I could mount the pulley onto. And I don't have a lathe running yet to make one that would work. Hence, the use of 1/2" drill bit :). Also, note my tensioning system.The right clamp on the drill acts as a pivot, and the rubber tube is pulling the drill handle by means of a marshmallow roasting stick, thus providing adjustable and surprisingly constant tension to the V-belt.
    The system turned out to be quite functional. In particular, I managed to:
  • Bore out the soft jaws
  • Learn that I need to raise the lathe quite a bit; otherwise my fingers scrape the board when I try to use that nice little black wheel
  • Learn that I need a decent way to measure the travel of the carriage on the bed. I already found an inexpensive dial indicator to aid me in that.
  • Learn that drill does not overheat (I wasn't sure if it would), but is loud enough to harrass my neighbours

    In other words, just a few minutes of lathe turning were a lot of fun and gave me something to do before the REAL motor arrives. For starters, I have some woodworking to do to set the lathe up more conveniently, and make sure things run quiet.

    I just had to take this picture because I have created very few things that are uglier, and most of those were my computer program code, not the real things you can touch and see.

    28 Oct. 2003 So, a few days ago I finally got my lathe. There were a few quirks during putting the thing together, but none that couldn't be fixed with a little of filing/grinding/lapping. Nicholas Carter's suggestion to lap the screw in the crosslide did wonders! I knew lapping helped things run smooth and with less friction, but didn't know it helped that much. I went from needing to apply a few pounds of torque to the little crank handle (making me worry it might snap off) to only a few ounces to acheive the same effect.