Milling machine spindle run out

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Milling machine spindle run out

This topic has 14 replies, 7 voices, and was last updated 17 February 2012 at 10:58 by Dave C.

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15 February 2012 at 21:19 #84859
Dave C
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@davec87625
I have just made some checks on my Harrison mill after having put a drill chuck and centre drill in to spot some holes. There was an obvious wobble at the drill tip. I first suspected the drill chuck arbour which was new. The chuck is a pretty good one and seems fine in the lathe. When I ran the arbour on its own and checked with a DTI there was a 4-5 though run out which seems pretty excessive. It is a new arbour as I say but I have to admit not an expensive one.

I then carried out more checks. When a test is carried out on the outer surface of the actual mill spindle there is absolutely no run out at all or movement of the needle on the DTI so I can assume the bearings are fine.

I have no way of checking the internal taper for run out but it is clean and very smooth with no obvious visual marks at all.

I then put in my new Vertex er32 chuck which shows 2 thou run out on the body but @ 4 though on the end of a 1.5″ bar when run in the chuck.

What can I reasonably expect for tolerances using the above equipment and is it normal perhaps that the internal taper is slightly out from the external surface.

Any advise would be appreciated.

I have searched for previous threads but they dont really answer my question.

Thanks

Dave
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15 February 2012 at 21:19 #5959
Dave C
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@davec87625
15 February 2012 at 22:01 #84867
Jon
Participant
@jon
Clamp something up in the drill and put the DTI on it.

The outsides can be different to the inside certainly if chinese.

DTI up the bore?
15 February 2012 at 22:41 #84872
MICHAEL WILLIAMS
Participant
@michaelwilliams41215
It is unlikely that the spindle of a Harrison mill is much out of true if the machine is in general good order .

As for you various runouts these should all be less than one thou . A plain arbour without any chuck fitted should run nearly dead true .

Be aware though that drills are almost always bent – runout of them could be anything even in good chuck .

Suggest strip everything down and look for minute burrs and bits of trapped swarf – when all is clean test again .

MW
15 February 2012 at 22:58 #84874
Versaboss
Participant
@versaboss
Hi Dave C,

wonder how you managed to put a 1.5″ bar in an ER32 collet chuck. My ER32 set only goes to 20 mm.

(also just a test for the so-called new editor, I see no differences…)

Greetings, Hansrudolf
16 February 2012 at 09:14 #84890
Dave C
Participant
@davec87625
Hi Hansrudolf

The bar was actually 0.5″ DIA but protruding from the chuck @ 1.5″ in length.

I was trying to explain where the measurements were taken.

MW

I will carry out some more checks as you say after a good clean down and more investigation. The machine seemed in good order until I came across this problem. It certainly hasn’t been abused as it was purchased from the estate of a well respected model engineer who produced some fine work.

Regarding the drill arbour, This was a chinese import and I dont hold out much confidence with its accuracy. You get what you pay for I guess.

regards to all

Dave
16 February 2012 at 09:23 #84894
John Haine
Participant
@johnhaine32865
Do you have a “finger” type DTI? You could mount that upside down to the table with the finger on the inside of the taper bore – that will show you the inherent spindle runout.
16 February 2012 at 11:36 #84904
Weldsol
Participant
@weldsol
Hi Dave a silly question but the 0.5" bar that you used was it just plain BMS or machined ? as plain bar is never truly round. You could check the bar with a micrometer.

Paul
16 February 2012 at 20:00 #84963
Sub Mandrel
Participant
@submandrel
Even a 'cheap chinese' drill arbor ought to run virtually true. The Vertex chuck body should't show run out..check for a loose bearing?

Neil
16 February 2012 at 21:18 #84978
Dave C
Participant
@davec87625
Paul

The bar was a new piece os silver steel and checks with the micrometer show all is well.

Neil

I have just been back to the workshop and removed the top cover on the spindle. All looks well an I have run with a DTI on the same top end of the spindle with absolutely no needle movement. so I have regreased and put back as found. I have also run with a DTI on the bottom end of the spindle with no needle movement at all. So I assume bearing wise all is ok. I have borrowed a finger type DTI as John suggested and run a check up the bore. The results were 0.03mm of movement on the dial which seems constant as far up as I can go.

The previous results which I have posted have been total needle movement on the DTI, Perhaps I should have halved these results for true run out ? Excuse my ignorance. Therefore the 2 Though run out on the vertex chuck is actually 1 Thou ?

Am I to assume that there is just an amount of wear in the bore or would that amount be acceptable. The bore has been cleaned and checked for swarf. It also looks uniform with no obvious signs of damage.

My Clakson chuck also shows 2 thou of needle movement on the body so I have to assume that it is all down to the bore and not the chucks.

Regards and thanks to all

Dave
17 February 2012 at 08:12 #85002
John Haine
Participant
@johnhaine32865
.03 mm is a thou. What sort of taper is it? Does a clean male taper fit properly? If socket is worn it probably wouldn’t. If socket not worn then runout was put in by the maker.
17 February 2012 at 09:31 #85006
Dave C
Participant
@davec87625
Hi John

It is Int30 taper. male tapers fit snuggly with no evidence of play. I cant see how it should wear as there are 2 driving lugs which would eliminate any slip. There is I have just noticed a very slight difference in the surface at the two positions adjacent to the driving lugs at about the same width, maybe 3/8" wide and this is where the 1 thou difference is showing. This is not all the way up the bore and obviously totally opposite to each other. I dont know if this is something that is meant to be there or is posssibly down to wear somehow ? The difference of the 1 thou is at these two positions with the rest of the bore being uniform. It is 1 thou larger though can I assume it shouldn't affect things greatly with the majority of the taper being uniform.

I am obviously stuck with things as they are but it would be nice to know. The machine is still more accurate than my ability and I have to say of a similar age too so I cant really complain.

Dave
17 February 2012 at 10:40 #85018
MICHAEL WILLIAMS
Participant
@michaelwilliams41215
Hi Dave C ,

Time for a bit of real engineering :

(1) Find your best ISO30 shank and do the Hi spot blue test of this shank into spindle bore .

Repeat test with shank inserted again at different positions roughly 120 degrees apart . Careful examination of bore and shank on test will show you how well they bed together and in particular if there are any high spots bad enough to send shank out of true .

(2) For each of the tests that you did before with dial gauge repeat them all but with all the various components turned around relative to one another by the same 120 degrees variations and see whether results are constant or vary at each assembly . If they vary you can by deductive reasoning work out where the errors are .

NB : Three tests at 120 degrees separations finds most errors but you can also do additional tests at odd angles if you wish . This editor is doing funny things and I'll have to stop . MW
17 February 2012 at 10:48 #85019
MICHAEL WILLIAMS
Participant
@michaelwilliams41215
More :

If you have still got the dogs in the ISO30 drive flange best to take them out temporarily for tests .

MW
17 February 2012 at 10:58 #85021
Dave C
Participant
@davec87625
Thanks Michael

That makes perfect logical sense to me. I will carry out the checks as you suggest.

Unfortunately I have to be away for 4 -5 weeks now on work commitments so I will wait untill I get back and can devote some time to the job.

I will post my findings at a later date.

My appologies to anybody else who offers any assistance but I will not be able to respond immediately whilst away.

Dave
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