Author Topic: Help with alingment of head stock  (Read 1292 times)

Offline lilyies

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Help with alingment of head stock
« on: September 02, 2017, 09:27:31 PM »
I have just refurbished the head stock on my old tiawanise lathe.
Have used a test bar for alignment.It is telling me that head stock
is running true when I travel the length of the test bar.It is also
telling me there is no taper when I put the indicator on the top of the
test bar. no run out in spindle mt5.Put the indictor at the end of
 test bar and rotate 8thou run out like an oval.?????  : :

Offline sparky961

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Re: Help with alingment of head stock
« Reply #1 on: September 02, 2017, 11:55:41 PM »
How did you validate the test bar before beginning? Seems suspect to me.

Offline lilyies

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Re: Help with alingment of head stock
« Reply #2 on: September 03, 2017, 12:51:22 AM »
Mate the test bar is ground to .0002 this thing has me baffeled.

Offline Pete.

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Re: Help with alingment of head stock
« Reply #3 on: September 03, 2017, 02:38:48 AM »
You can have no runout in the bar, no runout in the MT5 socket, but the bar will run out in the socket if there's dirt, rust or dings on either.

You have to fix the runout before using the bar to test the alignment, or you'll always get a false reading.

Offline lilyies

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Re: Help with alingment of head stock
« Reply #4 on: September 03, 2017, 04:13:26 AM »
Have no runout in head stock mt5 no runout in testbar.??? :scratch:

Offline jb3cx

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Re: Help with alingment of head stock
« Reply #5 on: September 03, 2017, 04:25:11 AM »
Have you tried with the test bar between centres?

Offline Joules

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Re: Help with alingment of head stock
« Reply #6 on: September 03, 2017, 05:14:28 AM »
Blue the taper on your test bar, insert and twist. Now pull it out as gently as you can, pulling it straight so it doesn't bump around in the taper.  Look at the contact pattern is it even, you might have to try this a few times.  Like wise with blue in the head stock taper you can do again with the test bar clean.

You may already have witness marks on the test bar.  If you do have a nick in the taper I would gently scrape it rather than hit it with a reamer.

Take readings along your test bar and rotate the spindle does the 8 thou gradually come in.  Clock the spindle outer at the rear of the lathe, any runout.
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline chipenter

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Re: Help with alingment of head stock
« Reply #7 on: September 03, 2017, 03:05:58 PM »
You can test the test bar using two vee blocks and a dti , any jumps of the needle is a ding that needs stoning off .
Jeff

Offline lilyies

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Re: Help with alingment of head stock
« Reply #8 on: September 03, 2017, 06:31:32 PM »
Have already done everything suggested so what next boy's.As you might imagine
I am about to tear my hair out.I think it is in the headstock but where??

Offline sparky961

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Re: Help with alingment of head stock
« Reply #9 on: September 03, 2017, 10:44:42 PM »
It is also telling me there is no taper when I put the indicator on the top of the test bar.

Huh?  Taper would be tested by running an indicator at 90 or 270, if designating the top as 0.

As for the rest of your tests, make sure you aren't inducing error due to indicator "sag" as a function of gravity.  You aren't completely clear where you're mounting the indicator and what the tip is contacting.

Don't tear your hair out.  Slow down and go back to first principles.  Make no assumptions!

Pictures, as always, would probably lend a clue here.

Offline nickle

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Re: Help with alingment of head stock
« Reply #10 on: September 03, 2017, 11:59:00 PM »
There is a good technique that will let you use the bar as is and evaluate your headstock alignment. Do a quick google for rollies dads method lathe alignment. The process is less dependant on precision alignment of the item in your chuck or headstock taper.

Regards,

Nick

Offline Pete.

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Re: Help with alingment of head stock
« Reply #11 on: September 04, 2017, 12:53:56 AM »
If you've checked the test bar then the first thing you have to do is get it running true in the taper. As I said further up you can have a perfectly good test bar and a socket that dials true but still have the bar running out if the interface between them is not perfect. Any dirt or dings will make it run out.

You might be able to improve the runout by setting the bar in firmly with a drift.

Check the socket at two different depths to make sure it's running co-axially with the spindle. If you can, run the lathe slowly and sweep a DTI up the taper very slowly to see if it kicks or jumps, indicating a burr or ding (or embedded swarf) in the taper.

Blue the test bar taper up (or use magic marker in a pinch) and set it in the socket, as Joules said above. If it doesn't fit perfectly it'll only remove the blue in a couple of tiny spots.

Until you get this test bar running true you are wasting your time checking alignment, it will always yield a false result.


Offline lilyies

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Re: Help with alingment of head stock
« Reply #12 on: September 04, 2017, 03:50:23 AM »
Pete have blued and checked the contact on the taper about 95%
I was thinking the spindle may be bent. But both ends of the spindle
run true.WTF

Offline Joules

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Re: Help with alingment of head stock
« Reply #13 on: September 04, 2017, 04:51:07 AM »
As has been said, some pictures would be very useful now. Did you remove the spindle and bearings from the headstock during refurbishment ?  Is the preload set, if not tighten it up some more and test. If you put a tool in the taper and push pull can you feel any movement or clicking as you rotate by hand.

I just read your introduction, do you have a model engineering society near by or know anyone else with a lathe.  Be as well to get a second "Hands On" opinion as we are all second guessing your skill level and abilities.
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline lilyies

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Re: Help with alingment of head stock
« Reply #14 on: September 04, 2017, 04:34:36 PM »
Joules I have not got a lot of machining experience but I have worked
with and around machinery all my work life.I am a am a rigging supervisor
on dragline builds so do a lot of work aligning big electric motors gearboxes large boring
bars ect.

Offline Joules

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Re: Help with alingment of head stock
« Reply #15 on: September 04, 2017, 04:52:12 PM »
OK sorry, can never tell if I am telling someone to suck eggs or talking way over what they are confident with.  You have me scratching my head over this one as the taper and bore can't both be good and then out when together ???
Just get doing and make swarf, you can decide what its going to be later.   :thumbup:

Offline lilyies

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Re: Help with alingment of head stock
« Reply #16 on: September 04, 2017, 07:06:00 PM »
Mate I have been at this for 5 days on and off.

Offline sparky961

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Re: Help with alingment of head stock
« Reply #17 on: September 04, 2017, 09:04:19 PM »
Mate I have been at this for 5 days on and off.

Take the next 5 days off then come back to it.  Bet things look different after a break. :)

Offline Fergus OMore

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Re: Help with alingment of head stock
« Reply #18 on: September 05, 2017, 01:16:53 PM »
'Myford' always suggested that you hold a round bar in the three jaw and  machine two rings at one setting- and then mike them.

Oddly I got a thing when I bought a very second hand Myford ML10.

It's not the classic way to evaluate the accuracy of your lathe but neither is what you are doing. 

Perhaps Georg Schlesinger is where you should really aim.

Norm

Offline gerritv

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Re: Help with alingment of head stock
« Reply #19 on: September 05, 2017, 06:57:53 PM »

Offline SwarfnStuff

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Re: Help with alingment of head stock
« Reply #20 on: September 06, 2017, 02:26:09 AM »
Thanks for posting that link gerritv, well worth bookmarking for future reference.
John B
Converting good metal into swarf sometimes ending up with something useful. ;-)

Online JonIndigoman

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Re: Help with alingment of head stock
« Reply #21 on: October 24, 2017, 05:28:36 PM »
Try googling "rollies dad's method". I've never tried it but it implies that you don't even need a straight test bar.