1018 Finish Cut

[JR49]

Jim, you have gotten some great advise already. All I want to add is TRY USING POWER FEED, it is impossible to hand feed as precise as the power feed (yes, I'm saying machines are better than Humans). I couldn't believe the difference for this novice. Happy Sunday, JR49

 

[Jim1946 SB9"]

Awesome advice so far. Wreck it is 2" and I don't currently have any carbide stuff. I will keep this in mind when I finally get some. Not sure the old Southbend could ever use it at its max production potential but I am sure there are some things I could use it for.

I wanted to show this photo of what I was getting and where I am now after trying the shear tool.

 

[itsme_Bernie]

Looks like you may need to round the end of your tool a little - a good hone- and make sure the power feed is set as fine.

Bernie


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[randyc]

Well I tried the Shear tool. All I can say is Wow it works. Very early in the process and still need to experiment with DOC and Feed and such but so far this Shear tool looks promising. Will probably still need a little emery cloth to finish but much less effort than starting with the ugly surface I had before.

Jim, the shear tool may seem like the ultimate answer at first but it does have shortcomings including very small DOC and feed. The cutting edge can wear quickly resulting in a tapered diameter over long workpieces. What's worse is that the wear is not usually eyeball detectable ! Takes a little magnification to see the tiny little wear spot. (This is one of the times when you should use lots of cutting oil on 1018, to minimize the tool wear, by the way.)

This won't be a problem for general work but one of the main uses for the shear tool is not necessarily to produce a good finish but to obtain very accurate diameters, shaving off a few "tenths" at a time using the compound set at about 6 degrees off the spindle axis (google it and you'll understand the technique).

A little taper can be an important problem - for a bearing fit as an example - and then one is right back to using a scrap of emery paper to straighten out the taper

Good on ya' for trying it out, though, best way to learn is by doing ! (FWIW one time I tried a brazed carbide AL tool as a shear tool after honing the edge with a diamond lap, and got some good results. Was able to run the spindle faster with less tool wear although this won't be an advantage on your South Bend with its limited maximum RPM. I still used very small DOC and feed, however.)

 

[kwoodhands]

Hi everyone.
Well I have started my first project on my 9" SB. I am struggling with surface finish I am cutting 1018 and want some pointers on finish cuts. At this time I still have lots of material to remove but would like to figure this out before I get to my final dimension. I have been reading about feeds and speeds but have yet to try power feed as I am not sure what feed rate to start with. Any advice about 1018 would be appreciated.

Grind an arc shape on HSS .The front relief 7° / 10°. The cutter should look like a C shape when looking down on the cutter. The radius is about 1/16". Grind the top and side rake about 5°. You may have to stone the cutter if there are any burrs.Center the tool on the work. Place a 6" steel rule between the cutter and the work.If the rule is plumb the tool is centered. If the top of the rule is away from you the tool the tool is high.If the rule is towards you the tool is low.
Once you are set up, use the powerfeed on the slowest travel. Spindle speed set about 350 rpm,not critical.Make your cuts .005 or so at first.You will be removing twice that amount when turning.Use a cutting oil, I use plumbers thread cutting oil on 1018.If you grind the HSS cutter like I said ,center it , use a lubricant ,the finish will be much better.
Usually I can turn a shaft or axle so none or almost no other work is involved. If you have to sand or file, then make light cuts instead. The most you should have to do is 400 grit paper or scotch brite pad.Don't be afraid of the powerfeed.
When you get close ,especially at the lowest travel speed you have plenty of time to stop the feed.
mike

 

[l. bacon]

Some thoughts I have on this finish subject: A manual lathe is a thread cutting lathe. no matter whether it is cutting a 8 thread per inch or .005 per revolution. Look at your rough surface with a magnifying glass or under a microscope and you will see what I mean. So a pointed tool will leave a threaded surface or that rough surface that you don't like. To smooth that surface, a tool with a less point should help. A tool that is wide, straight and parallel with the work surface will work but will likely chatter and leave an uneven finish, so a tool that is only as wide as to bridge across at least two threads should leave a smooth surface ,but it will probably be too difficult to adjust perfectly parallel to the work. A rounded tool that is wide as described previously is what seems to work best. It cuts out at least two of the previous threads and isn't so wide that it chatters. Of course there are other things that can cause a rough finish such as a loose and worn machine, dull or sharpened with poor relief angles, and all the other things mentioned in previous posts.

I hope this helps. This is just my 2 cents worth.