Tailstock Problem

[Dragon]

Hi , happy holidays ¶¶¶¶¶¶¶
I have g0602 lathe that I got last year and I am facing weird issue that making me chasing my tail all around the shop! any inputs, idea are appreciate

first I would like to say sorry for opening an old topic been repeated so many time BUT this time its little weird at less for me!

here is the tools I use in my tail stock :
ER 32 collet chuck HHIP <= .0002 confirmed brand new
lyndex (Japan) 3/16 collet Brand new .00005
3\16 center drill made in USA
dead center Royal USA made .00005 confirmed brand new

starrett last word indicator .0005 new old stock
noga style short magnetic holder

when I put the holder on the chuck and point the dial indicator on the first inside the opening of the tailstock quill and align the tailstock by tightening the both side screws: I get .0001 in both sides and .002 up and down

then when I put my deadcenter in the quill and check the reading I see almost .003 different in both sides!!! I didn't change the length of the quill as I keep it 5.5 out of the tail stock

and when I redial or realign the tailstock with the dead center in by keeping the dial on the end tip of the deadcenter and using same screws on both sides
I can align it again to .0001 both sides and .001 up and down!!

but when I re position my dial tip to the thick taper of the dead center the reading will be different again and start giving me .003 off in both sides!!

I re checked my dead center and I found no problem with it and TIR within .00005 in all taper area

same when I put the ER32 and use my USA new 3/16 center drill and point the dial shank of the drill the reading will be ~.004

I also checked my ER32 by checking it with my magnetic brown and sharp V block by putting the dial point on the drillcenter and rotate the shank (mt3) by hand and it giving me repeatable reading of less than .0002
and I don't change the location of the tailstock in every tool change also I don't over tight the quill as I use the same torque each time I tight the quill.


can you please tell me how to solve this problem or what is the cause of the problem you think?

I appreciate all your help

thank you
OZ

 

[talvare]

Oz,

I would first check the inside surface of the Morse taper in the tailstock quill for any imperfections. It only takes a tiny burr or flake of metal to cause a significant change in alignment of tools that you insert into the tailstock. Any burrs you may find can be carefully removed with an India stone, just be careful to only stone the imperfection.

Ted

 

[chips&more]

Are you just tinkering around? Maybe just looking for a problem? I have been in this field for about 50 years now and have never checked what you are doing. I’m not saying you don’t need to. But if you keep looking you will find ALL KINDS discrepancies throughout your machines and tooling. If you are making NASA parts then please continue with your inspection. If just making stuff, then only worry about the stuff that didn’t come out right…Good Luck, Dave

 

[Dragon]

Ted and Dave, thank you very much guys for your replies !
Dave; I agree with you that I should not looking for that accurate machining specially with china lathe!!

but the project I am trying to do is little difficult
I am trying to machine a true shaft that will be going in place of original 8mm KV motor shaft that will spin very High RPM and that shaft will be 6" long and the OD of that shaft should change from 8mm to 6 mm for 16mm long then reduce again to 5 mm and stay 5mm for the rest of its length
so its : 6" long with 2.5" 8mm then go down to 6mm continue 16mm then go down to 5mm diameter to the rest of it

this shaft will spin main gear in rc helicopter and need to be free of vibration

so I ordered the ER 32collet and the lyndex collet with Royal dead center just to get close OD and TIR as I can !

and I am using 4 jaw chuck and using o1 steel tooling so I can harden the shaft to RC_62

Ted;
I will take the quill a parts and check every thing I may see something need to be stoned down!
I appreciate your guys time
Oz

 

[stupoty]

Thats not going to be a fun job, well it will be very satisfying when you get one made corectly

I would aim at tolerance zones for it and concern my self with the areas that need to be very very acurate and worry less about parts of the shaft that can be outside tolerance.

Its a very long and very slender shaft.

I have used 1" wide abrasive strip for working small (and less small) long shafts to reasonable tolerances.

Probably worth making some experiments at the various diameters and seeing how much the shafts flex as your cutting them.

Stuart

 

[rgray]

It's going to be hard to keep thet straight if your machining it first and then hardening it.
Something that critical should probably be machined oversize then hardened and then ground to final size.

 

[Dragon]

The only one problem I have is that I don't have grinder !! And I think hardening the shaft will not make it smaller! I am not sure but I did one straight shaft 5mm and it was pretty good!

Here is few pics of the shaft that I am welling to do!
I also want to make another shaft to spin the main rotor blades and that shaft should be 10mm OD 9" long and also will reduce from 10mm to 9mm OD so that can go inside bearing blocks holders

My question here :
How your guys machine shafts with different OD's at the same time machining then with no flexing during the cut!!

I know most of you will say use ( fallow rest)
But I tried that didn't work And that because the are of the machining part is too damm small!! And that fallow rest jaws Need to drive on space!!! And need to adjust the Jaws every cut!!

Hope your guys can share some of your good ways to do these shafts!!
Thank you

 

[Dragon]

If I can get these shafts within .001 I will say ok
Since the .001 will not create much vibration and will not hurt the bearings or other frames screws

But again it's difficult to keep that shafts sturdy while machining them!!

If I can make some kind of support like fallow rest and can be automatically adjusting while cutting in different sizes! And small enough to stay within the cutting area will be greate!!

Otherwise I think it's not easy task!!
Oz

 

[Ulma Doctor]

with some forethought and some will, i believe you could adapt or fabricate an offset rollerbox for your tailstock or maybe create an adjustable box for a qctp for that matter.
you may need to do the machining in steps and have a few setup issues, but it is possible to do it!
i use roller boxes on my turret lathe to turn single diameters to size, a series of them could produce the shaft you are trying to make.
in case you have not seen roller boxes, they look like this:

 

[tq60]

Consider a collet for unfinished diameter then have shaft protrude small amount and perform work then slide it out a bit more working always near the Chuck then support with TS as needed.

You only need bearing fit where the bearing goes so the rest can be tiny bit under for a sliding fit that you can verify before moving work.

If using collet work will stay true and if using 3 jaw then mark one pivot and only use that one to loosen and tighten to allow stock to move.

This is easy work.

Be careful with heat treat as hardening makes it brittle and can warp it.

Unless this is large or having tight high g forces just use good material to begin with and no suggestion there.

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