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Lathe Spindle displacement ?

BGL

Hot Rolled
Joined
Sep 14, 2010
Location
Maryland, USA
2007 SL 10.
New to me, and has very low hours, consider it new! Seriously - I don't think it has ten hours of spindle on time. It is that clean, I need to look but trust me - its mint!

We came by this machine when the owner lightly crashed it and decided there is more to machining than he thought, PHD with deep pockets.

People with GEDs can run them, how hard can it be?

So seriously... I have never run a Haas lathe and I am struggling with a second opp with bored soft jaws to get the parts true. But a lathe is a lathe and an easily deflected spindle is bad - I can't do this on our Hardinge or Monarch.

Cut to the end - I set a 0.0001" Indicator on the tool post, touching side of chuck. With a 1.250" steel bar stock 8" from chuck jaw face.
Palm of hand on end, elbow on hip I can deflect the chuck 0.0004" pull back 0.0002". Total of 0.0006" agreed?

Using a bathroom scale against the concrete wall I can get just about 80 lbs pushing. No idea on pull but I imagine it less.

Tell me this is wrong please. We are contacting Haas for a service call. Any experience to share?
 
its an interesting method, what is your advantage ratio in your prybar setup? if your putting hundreds of pounds something is going to flex to some degree. (80LX x20=lots of force!)
what is the indicator mounted to? are you flexing that? or measuring the movement between it AND the spindle?
Is your indicator angle set correctly, or is the measurement exaggerated on the hypotenuse of movement?
a picture of your setup may help explain.

Ive never pushed around their lathes, but my tm mill was pretty flexy. run hard and light finish cut and it still gave great results!
 
Unfortunately I have no pictures. All the details of proper indicator set up were employed. Its base solidly on the side of the tool post.
and force applied in the X axis. I cannot imagine any influence on the indicator.

If you take in consideration the center point of the bearing behind the chuck to the point of pressure, yes that is close to 20". Correct me if
I am wrong but that is in my math 20" X 80lbs = 133 pounds force. But then there is more to the spindle then one bearing. Yes the chuck is properly
bolted and chuck closed with pressure of 130psi, 1.250" bored steel jaws.

I could not imagine one could set a tool rest like on a wood lathe and hold a tool by hand and make anything but random gouges.

I get what your saying on a VMC, shocked me that I can push on the table and get 0.003" of movement to the spindle and spindle head to table yet I can make parts to 0.001" or better. Movement from spindle relative to work is different, the control is smarter and stronger than me and actively pushes back to maintain position. In static mode [asfaik] it is casually holding position, in dynamic it is holding to a much smaller value. Both VMC and lathe work this way in machine movements but this is out of the dynamics, no force is applied to the tool block where the magnetic base is solidly sitting in any way - don't tell me I am distorting the casting.

If you were to set a long bar in your mills tool holder, indicator on the tool holder, base on the outer housing casting - see if you can move it.

A lathe spindle is like the VMC spindle - an ignorant log (no insult intended) two opposed bearings holding a steel tube - its big, simple and very strong. To my simple mind I should might be able to influence if I put a three foot bar in the chuck and used a strap to our 6000 lb forklift. I see in the service manual the spindle casting is seperate from the base loose bolts - no that can't be.

I am open to the idea I am overthinking it, that is my superpower. But I'm going with something is wrong here and we are calling in an expert.

Expert; noun, compound word - Ex, has been or once was. spurt, a drip forced by pressure.
By that definition I am. Hope we get one with experience, thats the pool the spurt comes from, the deeper the better!

Cheers!
 








 
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