What Have I done wrong?

[joebiplane]

I have my Logan 820 up and running )and
Everything works, sounds quite smooth ( except for the Metal lacing ) but when I attempted to reduce the size of a 1" alum bar I cant get a smooth surface :angry:
I am using a small ( 1/4 ") tool bit HSS and it is in a bit holder that is in the "Lantern" holder in my compound rest.
The results look almost like threads I have the longitude feed set as slow as it will go on the QC gear box.
I am including a photo that is high resolution so it is BIG...I apologize for that but I wanted to give you as clear a shot as I could ( probably a waste of space)
When feeding manually I can improve the finish a bit...but not completly and I have a Compact 8 lathe so I know what it should look like.
Beside having the Emco compact 8, , I am a green horn and just surprised, silly, that the this Logan :huh:thing works at all :lmao my first lathe refurbish)
I tried the same tool bit in my emco and it works fine... I set the tool just a " tad " ( 2RCH) below center any ideas ???
The machine is almost 70 years old....but so am I ...so thats a poor excuse. The gibs are snug...I resolved cross side slop with a new cross slide nut. Everthing feels firm, tight and movable as it should
Any Ideas ???
as always Thanks
joe

 

[pjf134]

Try putting the tool on center and feed it slow manual and see what happens. Take a light cut, sometimes feeding too fast will give lines on the bar. It just happened to me today on some brass, I slowed the feed and got a nice finish. Just a thought.
Paul

 

[Tony Wells]

You may want to check your spindle bearings as well. Do you know the feedrate, exactly?

 

[pjf134]

Joe,
I missed the part about manual feed in your post, so I would try doing the lift test on your spindle to see how much slop there is on it. The lift test is covered in the download section I am almost sure. Is this the first time it has run since the rebuilt? Are you hearing any chatter when cutting? How much material are you cutting off per pass? Maybe take a light cut to see if that helps if you are cutting deep. Just throwing some things out there.
Paul

 

[hq308]

I'm no expert (not even close) but I get a similar finish to that if my tooling isn't sharp enough or is incorrectly ground or positioned.

 

[pjf134]

David,
He did say he took off the bit and put it on his compact 8 and it worked there. Don't feel bad David, I missed the part of him trying running manual, as I did not remember that when I first read it. Since it was just rebuilt, I would go all over it with a indicator to see if everything is good. How far is the material sticking out of the chuck, and is it supported if too long? Are you using a pointed tip or rounded tip for a cutter, maybe round the tip some and slow down feed rate. Just trying to cover all the bases to see what works.
Paul

 

[Starlight Tools]

make sure it is not in thread mode instead of feed mode as well. Not sure on the 820 how that works. Is it half screws for both feed and thread or half nuts for thread and feed rod for feed?

Walter

 

[ScrapMetal]

I tried the same tool bit in my emco and it works fine... I set the tool just a " tad " ( 2RCH) below center any ideas ???

As I understand it, the tool should be at least 2RCH above center. As some have said, it almost looks like your using the half nuts instead of the friction feed. I am probably the least qualified to help so take anything I write for what it's worth.

-Ron :biggrin:

 

[hq308]

David,
He did say he took off the bit and put it on his compact 8 and it worked there. Don't feel bad David, I missed the part of him trying running manual, as I did not remember that when I first read it. Since it was just rebuilt, I would go all over it with a indicator to see if everything is good. How far is the material sticking out of the chuck, and is it supported if too long? Are you using a pointed tip or rounded tip for a cutter, maybe round the tip some and slow down feed rate. Just trying to cover all the bases to see what works.
Paul

Yep I missed that bit, told you I'm no expert.:biggrin:

 

[Davo J]

I would check your spindle bearings as said above and also check your gib adjustment. Could you post a picture of the tool?

Dave