Craftsman/Atlas 618 [page 7]
Wednesday, Sep 7 2016
The play in the spindle was partly due to worn bearings – they are oilite bushings in this old lathe, not the tapered roller bearings that were in the Atlas version. Sears went to the Timkin tapered bearings in the early ’50s I believe. None of the local shops had the sleeve bearings in the size I needed so I ordered some on line. $4 for new bearing. Shippingn was about the same.
I installed the bearings and re-installed the spindle. The new bearings reduced the spindle up and down play from .005” to less than .002”. Axial run out measured at the front of the spindle flange went from .003” to about .002”. Radial run out measured at the top of the spindle flange stayed the same at 0.003”.
I tried to measure the run-out at the taper but the surface of the taper is so chewed up it is impossibe to get a good reading. It doesn’t help that I dont have a MT2 center. I think this is the best I’m going to get. [See the Sep 10 entry for a better measurement method.]
Tomorrow I’ll try to machine the face plate to size so I can mount the chuck. It will be the first cuts I’ve made on this lathe. It will also be the first cuts I’ve made on any lathe in 45+ years. I need to machine the face plate to mount the chuck so I can machine the spacers needed to install the back gears.
When that’s done I’ll look at machining a new ball-crank to replace the broken unit for the cross slide. That will likely stretch my skills to the max.
Friday, Sep 9 2016
Yesterday I machined the backing plate and mounted the chuck. I didn’t do that great of a job. I’ll fix it later. In the mean while I wanted to check a few things.
I chucked up and faced some scrap steel. I left the little tit on the end (the tool wasn’t perfectly centered) to rough check tailstock alignment. Oh oh. I adjusted the tailstock so the horizontal alignment looked good, but the height is off. The tailstock is above center. Not sure what I’m going to do about that.
Saturday, Sep 10 2016
I attempted to check if the tailstock was parallel to the ways. First I measured between the ways and the bottom of the ram using a cylinder bore gauge. I loosened the set screw abnd rotated the ram 90 degrees so the slot in the bottom of the ram didn’t mess up the measurements. A parallel was laid across the ways to use as the base of the measurement. There is about .002” drop between the end of the ram and the base of the ram when fully extended. I repeated the test with the tailstock at various positions on the bed of the lathe. Same values. I then put the tailstock back to normal configuration and installed the chuck. Measuring from the top of the chuck to the ways with a test indicator as the ram was extended shows about the same drop. I’m going to call the tailstock good enough. On to the headstock.
The lathe did not come with a center to fit the headstock taper but it did come with a taper mounted chuck. The chuck is bell mouthed and not very usable as a chuck. I can use it to measure spindle run-out, though. Wish I had remembered that on Wednesday.
The pictures show the worst measurement. I removed the chuck, made sure the tapers were as clean as I could get them, and then repeated the test. Only .008” out this time. I repeated the test several times rotating how the chuck was mounted in the taper each try. I also switched to marking the spindle for high/low spots, not the taper on the chuck. The problem is with the spindle and its magnitude is .008”. The high spot is 180˚ from the low spot.