Surface finish problems

[gzig5]

Tim,
When I get the phonographing effect you describe on my Craftsman lathe with mild steel, I have had good luck by reversing the feed direction on the last cut. I usually take 2-3 thou off with HSS bits for the finish cut and the carraige traveling under power towards the headstock. I disengage the halfnuts at end of cut, turn off the lathe, reverse the tumbeler lever so the carraige goes towards the tailstock, turn on the lathe and then engage the halfnuts. This is done without touching the depth of cut. Doing this seems to take the "threads" off because the carriage is being pushed by the other side of the lead screw and is not in the same position relative to the work and the tool takes off the high spots.

The other option is leaving a couple thou to file or sand down.
Greg

[cybor462]

cut much 1018 and find as other said, carbide with a decent radius and fast spindle speeds with a slower feed. Must use coolant, I use flood and always get a mirror finish.

Tool must be on center, and yes I use Grizz cheapo holders with positive rake. Thier carbide is also C2 which is not the best but with a decent radius it does well.

[Spin Doctor]

I've usually found that with 1018 moderate top rake of about 5 to 7 degrees that slopes away from the direction of cut and the rear of the lathe combined with a tool nose radius of .05 to .1" and a moderate feed and speed works quite well as long as cutting fluid is used. It won't be as good a finish as ground but then 1018 doesn't grind that well anyways. Another option is to take a facing tool that is ground with no tool nose radius and turn it upside down and use it as ascraping tool with the edge between the side and end clearances being used as the cutting edge. That one I got from Home Shop Machinist years ago. We used to have to turn bearing diameters on large shafts for presses and sometimes we had to use that trick to get finished size and the surface finish we wanted. Plus aside from its machining characteristics I fail to see the almost mythical status that 1144 seems to hold in the HSM community. Its' sulfur content alone is enough to make me think twice as it does not lend itself to good welding applications. IMO 4140, especially 4140 TG&P is a far better material in almost any application that would see either 1018 or 1144. Just my $.02 so take it for what it is worth.

[h12721]

<<<<CRS 1018 machine over size and file and sand to size . You want good machined finish use 1020 hot roll and machine to size will weld good.1144 stress proof 12L14 will not weld 1215 can be welded.>>>>

Can you silver solder or braze 12L14?
Hilmar

[dp]

Some steel is ornery, leaving a "mouse tongue" finish with normal tools. A tangential tool may be helpful, mainly because of the steep rake angle; I generally get a better finish with this tool, especially cutting left to right.

I have a tangential tool I made for my shaper that I tried out on my lathe with 1018 in the chuck and it didn't do all that well. Better than what I had but it still left rings here and there. I also file and sand to fit and finish.

[h12721]

[QUOTE=h12721]<<<<CRS 1018 machine over size and file and sand to size . You want good machined finish use 1020 hot roll and machine to size will weld good.1144 stress proof 12L14 will not weld 1215 can be welded.>>>>

Can you silver solder or braze 12L14?
Hilmar

[dp]

Found an interesting video at youtube that shows a microscopic view of the cutting process and a (very) brief explanation of finish:

http://www.youtube.com/watch?v=86-xKFbdnOo