[Pxsi]

I have recently purchased a new 9x20 lathe, and am having problems with it holding parts strait. If I put the shank of and end mill in the chuck and put a dial indicator on it I get a round out of .003”.

I figured that this was due to my high quality Chinese 3 jaw chuck, so I got a new adaptor and 4 jaw chuck from LittleMachineShop.com. I installed the new screw on adaptor and put an indicator its face to check it, and I still have a contour of .003”. You can hand turn the spindle to the high spot, so it is not bearing slop.

I now understand that you have to shim the chuck to eliminate round out. My question is, is it best to make an aluminum shim plate to fit between the chuck and the screw on adaptor, or to try to grind the screw on plate with a tool post grinder?

Pxsi

edit "I accidentally put this thread in the wrong place, is there a way to move it?”

[DDM]

It sounds like your bearings to me. I don't know if you can tear it apart and see what is going on and tighten things up or replace the bearings, could be the main shaft and spindle arn't concentric with the bearings causing the runout. With the 4 jaw on there you should be able to dial it right in at one point on the work. Does the Lathe make any strange vibrations like bearing noise or something is out of balance? I'd take some 1" Drill rod have about a foot stick out, dial it in at the face of the 4 jaw and check the end sticking out for concentricity. that will tell you if something is not lined up right. Tell us what you find out, that's a nice size lathe for the home shop.

Carl

[Runner4404spd]

i had an issues with my 9x20 as well. i ahd to take the spindle apart, clean the bearings, relube , then reassemble. after i did this i was still getting an error and found the front right bolt that holds the spindle to the lathe bed was stripped. had to take it all apart again and insert helicoil. finally everything is lining up. make sure that your spindle bearings are tight enough first.

[Pxsi]

I'll give that a try and see what happens.

Pxsi

[pepo]

You should install the adapter on the spindle and face it off just enough to clean it up. If it has .003 runout only take off .005. It is probably cast iron so grinding it is not required. With a 4 jaw chuck you can of course adjust the runout on the diameter as close as you can measure. By the way .003 runout for a 3 jaw is pretty much the norm. Whoever told you to shim the chuck to the adapter is blowing smoke up your a$$ or doesnt know any better. Id ignore this clown in the future. Just a guess,its the outfit that sold you the chuck right?

[dertsap]

I'll give that a try and see what happens.

Pxsi

if the lathe is new why not get the company you bought it from do it ,no reason you should be having to repair a new machine , doesn't it have a warranty ?

[Pxsi]

Dertsap, the machine is from harbor freight, so when you get them new they need some work to get them in good working order. I do have a warrantee, but it’s more for broken parts and stuff. I could call them and get them to mess with it, but I would rather do it myself and take the time to get it right. If when I’m done it is worse than when I started, then I call them to fix it.

Pepo it was a different web site that said to do that. This is the reason I joined CNCZone.

Pxsi

[pepo]

Pxsi, I am just telling you what 35 years in the machine trades has taught me. Chuck adapters are always put on the spindle they will be used on and cut to run true,that is how it is done. If the face of the spindle is running true and you put the adapter on and it is making intimate contact with the spindle face,and you have .003 runout (contour?) guess what...........your adapter is out of parellel .003. If you want to make an aluminum adapter plate for the chucks adapter plate,knock yourself out. But are you going to make the aluminum adapter plate for the chuck adapter plate parellel and shim it too? Or will you machine the aluminum adapter plate that you have attached to the other adapter plate when it is installed on the spindle and forget the shims? My freind you are overthinking this,face it off real nice,bolt your new chuck on and run the machine. It aint rocket science. BTW its runout,not round out or contour.

[Pxsi]

I was hoping that there would be a simple fix. I have never worked with cast iron so that will be a learning experience.

Pxsi