Saddle causing .150 taper 3” off chuck no tailstock need help.

Now that you mentioned a crash I believe the headstock has shifted. The test I mentioned earlier will prove it.
Pierre
 
pdentrem said:
Now that you mentioned a crash I believe the headstock has shifted. The test I mentioned earlier will prove it.
Pierre
Click to expand...
Thats why i sujested turn between centes as a test as i dident know if OP had a test bar for mesuring it.

Stu
 
It’s an interesting problem. I’d suggest getting some sleep, and coming back with fresh eyes.
 
Does it cut taper when hand feeding also? Seems like it must be a shifted headstock, I would check for that
Mark
 
I've had a shifted headstock and it cut a .005" taper over 10 ". It takes about an hour or two of adjusting(by very small amounts) and then taper goes away.
After adjusting I'm at .0001" taper per 10".
 
stupoty said:
a part between centers "should" turn with no taper even if your head is out of line.
Click to expand...

That is Not correct.....If either the headstock or tail stock or both are "Out of Line" with each other it will turn a taper, Unless (and this is a HUGE "UNLESS") Both the head AND tail stock somehow happen to be "off center" the exact same distance making the barstock parallel to the carriage travel which is Not Likely to happen.
 
Latinrascalrg1 said:
That is Not correct.....If either the headstock or tail stock or both are "Out of Line" with each other it will turn a taper, Unless (and this is a HUGE "UNLESS") Both the head AND tail stock somehow happen to be "off center" the exact same distance making the barstock parallel to the carriage travel which is Not Likely to happen.
Click to expand...

Yeah I see what your saying but a center in the head stock and slightly tweaked, lined up with a tail stock center aligned to the head stock center (OP said tail stock was dead nuts to center) will exhibit much less taper than an out of line head with a chuck holding a part in a fixed axis.

I don't see how you would have the tail stock not lined up with the head stock if you set it up to match your head end? You would generally dial in the tail stock to align to the head I would have thought.

Might be just the way I align my tail stock, I check their point to point when turning between centers and adjust the tail stock to remove taper. If you could do that it would show the saddle was tracking repeatably parallel and not some sort of gib issue.

But yeah caveats apply mileage may vary.

And I probably worded it badly.

Stu
 
stupoty said:
I don't see how you would have the tail stock not lined up with the head stock if you set it up to match your head end? You would generally dial in the tail stock to align to the head I would have thought.
Click to expand...

Yes I agree and would think unless the person was new to the trade and uninformed that they would dial in their machines if possible. However, from what ive learned thus far, depending on how one goes about this Alignment process the tail stock may or may not align perfectly with the headstock over then entire bed length based on the conditions of the mating surfaces and how true they are on each machine. Normally most of the wear is close to the headstock so if you placed the tailstock in the well worn area of the bed to dial it in with the headstock then there would be a very very good possibility for it to be off in areas that are not as worn or vise-versa.

Now i may be WAY OFF here but right or wrong this is what ive learned on the subject but that don't mean I'm not willing to learn something new about it so please correct me if I'm wrong.
 
Latinrascalrg1 said:
Yes I agree and would think unless the person was new to the trade and uninformed that they would dial in their machines if possible. However, from what ive learned thus far, depending on how one goes about this Alignment process the tail stock may or may not align perfectly with the headstock over then entire bed length based on the conditions of the mating surfaces and how true they are on each machine. Normally most of the wear is close to the headstock so if you placed the tailstock in the well worn area of the bed to dial it in with the headstock then there would be a very very good possibility for it to be off in areas that are not as worn or vise-versa.

Now i may be WAY OFF here but right or wrong this is what ive learned on the subject but that don't mean I'm not willing to learn something new about it so please correct me if I'm wrong.
Click to expand...

Yeah I see that bed will cause some issues with this, I do "point to point" my centers for alignment but my sadle and tail stock travel on two different sets of ways so I guess thats another source of inaccuracy. The sadle ways are somewhat warn near my head stock and the tail stock ways are fairly immaculate all over (apart from where a previous owner ground an extra bit of swing for something that didn't fit).

You could use this factor to find the most worn area of your ways like this I guess.

I'm getting the thread off topic , sorry about that.


Either way It to me looks like a head miss alignment issue rather than a saddle issue especialy as the same result happens with the compond slide set to zero degree's, definitely worth a check.

As others have said i'f you have some known strait stock or test bar you could mount it in the chuck, maybe use the tail stock to move an indicator , this would rule out a saddle issue. OP has prism ways so it should be stable enough to slide the tail stock with it lose and still be quite stable with regard to position.

Running a test indicator up and down a test bar using the saddle, wont be very helpful if the saddle is suspected as the root of the issue perhaps ?

Stu
 
You must log in or register to reply here.
Back
Top