Advice on feedrate needed

[350xfire]

Guys:
I have been running my $300 12x36 lathe quite successfully for the last week or so. One thing that I am not too fond of is the finish it is leaving on my parts. I have it set to the lowest feed rate possible (0.04") and it leaves pretty noticeable lines on the piece. I have tried changind feedrates and spindle speed and still the same. Now, I'm not saying the finish is horrible, but my HFT 10x lathe left pretty nice finished on my work.

I was wondering, where I need to go with this, bigger radiused cutting tools or anything else? Oh, BTW, I am using some of those 5 for $25 "Carbide" HFT turning tools and I have also tried a Grizzly threading tool (the cheap one)... The Grizzly leaves the better finish.

Also, I usually run at highest speed 1500 rpm, but have tried 1000 and 600 with the same result!

Thanks

 

[precisionworks]

I usually run at highest speed 1500 rpm

In mild steel to medium carbon steel, try 150 sfpm to 200 sfpm. Slowest feed rate & at least enough DOC to fully engage the tip radius. Support the free end of the work with a live center, unless working right next to the chuck. "Right next to the chuck" varies with workpiece diameter, if the part is 1/8" diameter, have no more than 1/4" stickout. If the part is 1" diameter, have no more than 2" stickout.

Make sure tip of tool is dead on center.

Some materials turn badly, with HRS and CRS being two of the worst. Try something easy like 12L14 or 1144 Stressproof (both available online or by phone). If you still don't get a nice finish in 12L14 or 1144 Stressproof, check tightness of headstock bearings, tightness of cross slide gibs, etc.

 

[350xfire]

Thanks... I still don't have a qctp so may be my bit is not centered. Should be getting it this week!

 

[gadget_lover]

You can center the tip by simply adding shims under the tool to raise it or grind it down to lower it.

When I used a 4 station toolpost, I used the steel bands from a packing crate as shims. People often use a few leaves from a feeler gauge as shims.

Daniel

 

[precisionworks]

When I used a 4 station toolpost, I used the steel bands from a packing crate as shims.

+1

I worked in a shop that had a BIG 4-way post ... after a while it wasn't hard to grab almost any tool from the cabinet & know how much packing was needed under the tool.

The 4-way is a couple of steps above the lantern post that was standard issue for most of a century. The problem is that almost every job requires more than four tools, so one (or more) of the four stations is constantly being switched out. Aloris, in 1946, invented the QCTP as we know it today - specifically to address the shortcomings of both the 4-way and the lantern post.

 

[350xfire]

Got my QCTP in. Turns out the old post was not held by a press fit bolt. It was threaded. I just had to take the QCTP bolt and rethread to 5/8" NC11 and it works great!! No more shims!