Craftsman 109 Lathe - Spindle

It seems is a well known fact that Craftsman 109 has a weak spindle. The spindle is just over 1/2 inch in diameter (0.550"), and is easily bent. On the lathe I bought, with its age, I'd have to assume that it is bent. So when I have it stripped into parts, I took the opportunity to measure it.

I googled and it seems that people are checking the spindle with dial indicators. I have one which I recently bought, but I don't have a holder. Since the dial indicator does not need much force to hold it in place, I just put it on top of a few boxes and blocks and it worked fine.

It is off. So I marked it, took it off the headstock, and whacked it with a hammer. After a few tries, I have finally get it close enough, and on it goes.

Here is the test cut after straightening the spindle. On the left was the best I can get before rebuilding, and on the right is with the newly straighten spindle. It really looks much better.

The advantage of having a weak spindle is that it can be corrected really easily if needed.

Craftsman 109 Lathe - Setup

I have been thinking about getting a lathe for a while. When I was building my 3D printers and CNCs, there is constantly needs to make some parts. Some of the reasons are for lower the cost compared to buying from stores. Some of the reasons are just that the parts needed is not available commercially, and needed to be custom made.

So I finally saw this lathe on Craigslist listed for $160. It is for a Craftsman 109 lathe. I knew nothing about that lathe at the time. After some quick reading, I found that this was a really popular hobbyist's lathe in early part of last century. After a quick negotiation, I got it for $140, and went on to pick it up.

A lot of information on this lathe can be found on Internet. The lathe I have has a model number 109.20630. According to the website, it was on sale on 1945. That puts it at almost 70 years old now.

The guy who sold it to me was kind enough to show me how it works. Before that point, I have never operated a lathe. So all is very exciting. I took it home. Of course the first thing I did is promptly strip it into pieces. This model of lathe comes with thread cutting gears. The last owner has never put it up, so they are all in a tin box. After some study, I found that it is missing a few gears. And a search found that Craftsman 109 (sometimes called AA 109 for Ann Arbor who made it for Sears) is a very popular vintage lathe. Parts are are readily available on eBay and also available in the Home Shop Supply (a shop specializes in Craftsman 109 parts), but quite expensive if to get it complete. Oh well, I will figure out a way later.

The other minor issue with it is that it comes with a 3" chuck with only outside jaws. With a call to the last owner, I was told that that's all he has. Fortunately, there is the Little Machine Shop, which sales all the stuff a home machinist will need. $33 plus tax and shipping gets me a set of inside jaws that works with the chuck. It is not arrived yet when the picture below was taken.

This is how the lathe looks like when everything is put back together, spindle straightened, and everything tightened. It is really not too bad for a piece of 70-year-old machine.

Homemade CNC2 (Z Head)

The first thing I built for the CNC is the Z head. As a starting point , I went to Ebay and got a cheap linear slider for $20. It is the black metal slider you see in the picture below. It is made by DI, and has a travel range of a bit over 2 inches (which is sufficient for a CNC). I also plan to use the tool holder I have left from my ShapeOko after I have converted it into a 3D printer.

I have been thinking about different materials for the base board. Aluminum is definitely an options. But after some consideration, I decided to use wood. It is very easy to cut and shape, and has great strength weight ratio. It is cheap and easy to acquire too. The only downside of it is that the bulk of the size needed to reach the strength needed. But that is an acceptable trade-off for this build, as I can always replace them later. So here is the top plate of my Z head, with holes drilled for mounting.

These are assembled together as below, with a 300W spindle (which I also got from Ebay) mounted on the tool holder.

Next, we need put together the linear drive. For the Z-axis, I used a simple threaded rod going through a HWPE block. The HWPE block is a low friction plastic and is used here to achieve low backlash linear drive. It is a very simple setup. The threaded rod is hold with flanged bushing that fits into the wood blocks. The bushing is made of bronze with built-in lubrication. Two nylon insert lock nuts are used on each end as the holding points (which rides on the flange of the bushing). The stepper motor mount is made with an angle aluminum with a few drilled holes. Again, the coupler is purchased from Ebay.

Here is how everything are put together. A few more nuts are added for mounting the Z-Head plate to the Z post.

Homemade CNC2 (Planning)

Since I built my first CNC with ShapeOko (see my previous post) as a learning practice project, I have being thinking about designing one by myself and build it. I have since converted the ShapeOko into a 3D printer and gave it away in a hurry. So for the new build, I will have to start from scratch and bootstrap it again. This is challenging because as we know it usually takes a CNC to build a CNC.

One thing I am thinking differently now is that I may want to build a CNC just as a CNC, instead of a potential CNC / 3D Printer combo. I have looked at a few milling machines and their CNC conversion. Also from my experience playing with my last build, I realize that it maybe advantageous to have a CNC with fixed tool head (and Z axial) with a separate X/Y compound table (as in traditional CNC). One advantage of this configuration is that enables easy change of tools without disturbing X and Y position. It also makes more sturdy and stable machines too, which is more important for CNC machines.

I have looked at the Harbor Freight milling machine (at $600). Another one of interest is Proxxon milling machine MF70 (at $400). But both of them are a little expensive. Then I found that the compound table of the Proxxon machine can be had for $90. That is perfect.

My plan is to build the head and the frame from there, and then put it with the compound table. Afterward, I can use it as a mini milling machine to mill the parts that is need for CNC conversion and go from there.