Craftsman/Atlas 618 [page 13]
Monday, Nov 28 2016
I’ve spent part of this month converting expensive stock into useless chips in an attempt to learn how to operate the beast. The carriage stop I made is helpful, but a bit fiddly to move around. I see how a second stop could make some jobs easier. I also bought a cheap bench top drill press.
This is what I came up with. The slot is the body of the stop is the width of the ways. I don’t have a mill so I made the slot by boring a hole of the appropriate diameter and depth then spent a bunch of time filing the edges to get the needed shape. The marks on the bottom of the stop that are a larger diamter than the slot are due to a learning experience.
I was using a left hand turning tool to bore the hole. Once I got deeper than the relief cut into the end of the tool the bottom of the tool started hitting the part. It took me a while to understand where the vibration and chatter were coming from. Once I switched to a boring bar – after all, I was boring a hole even though I didn’t think of it that way – all was well.
I turned a circular cam at the end of a steel rod by offsetting the rod in my four jaw chuck. I turned the rest of the steel rod down to size using the three jaw chuck and drilled and threaded a hole to attach the handle. The rod fit in a hole drilled in the body of the stop next to the slot.
The lever is a piece of mild steel trimmed to length. I added the brass collar with a set screw to control the depth of the cam. If pulled up too tight it would bind in the body of the stop. The brass piece was found in a junk drawer. I drilled it out to match the diameter of cam shaft and tapped it for the set screw.
This is the stop in use. Takes about a second to unlock, reposition, and lock again. Itis quite useful for setting a rough limit for carriage movement. If I hit against the stop hard enough it will move. Not a lot, but enough that I wouldn’t depend upon it if precise measurements are needed.
I may modify the stop to add a dial indicator. Not sure, yet.
Wednesday, Nov 30 2016
I added an extension to the small end of the carriage stop held on with a couple of 8-32 cap screws. The extension is tapped for a 1/4-20 screw which holds the dial indicator in place. I like this better than using a magnetic base for the indicator as I’d originally planned. This is easier to move into place, easier to remove, and it doesn’t attract chips when turning ferromagnetic metals.
However, the indicator is thrown off by movement of the cross slide. The slide is not square and the gib screw adjustment can interfere with the nose. For now I’ve angled the nose down to the carriage (not shown). I’m aware that the reading is no longer accurate due to cosine error. I’ll take care of this issue, later.