Chester’s CQ2365/ 920

[Stephen RowleyParticipant @stephenrowley13300]

My spindle will not run true.

[Stephen RowleyParticipant @stephenrowley13300]

I have a Chester CQ2365 which is the same as the 920 but is older. I
bought the lathe some 5 years age but due to a house fire, moving twice
and a back injury the lathe has not been used for 4 years until 5 weeks
ago when after giving it a good clean and oil I put a peace of 8mm par
in the chuck to find that it is running out by about 10 thou.  I then
find out that in the first move my son and his mate had dropped the
lathe so I thought that the spindle was bent and contacted Chester’s and
that were very helpful and today I fitted a replacement spindle but the
lathe still turns 10 thou out which is good if I want eccentrics.

Can anyone come up whit an idea why or what I can do.

I
am not an engineer as all I know came from school some 40 years ago and
as I was good at scroll work the teacher was more concerned that I
finished his new gates that teach me more about the lathe.

I there is anyone who lives in Whitchurch Shropshire and would like to come and have a look I would be very grateful.  jsk.  

[John Stevenson 1Participant @johnstevenson1]

Chances of having two bent spindles and one being new is quite remote.

 

Sounds more like chuck fixing.

 

How is the chuck secured on this machine ?

 

John S.

[Stephen RowleyParticipant @stephenrowley13300]

Hi john

the chuck is a screw fitting. I have tried touching the side of the chuck with a tool in the tool post and turning the chuck by hand and again it is out and so is the face plat and the four jaw chuck.

James

[John OlsenParticipant @johnolsen79199]

Hi JSK,

I would suggest eliminating the variables by taking the chuck off and try a dial gauge against the inside of the spindle taper. The small type with the lever would be easier than a plunger type. With that you should be able to detect any runout easily . My guess would be that it is a chuck problem. Is this a chuck with a backing plate? If so is it a close fit on the backing plate or has someone done the trick of allowing some clearance so you can centre the chuck up with a soft face hammer. If it is set up like that then a good bump might have moved the chuck off centre on the backing plate.

 

Actually if you put a centre in the spindle and another in the tailstock, and bring them close you would easily be able to see if there is any wobble in the spindle one as it goes around .

 

regards

Another John

[JasonBModerator @jasonb]

Just a thought has the belt taken on a “set” from standing tensioned in one positioncausing it to pull on the spindle with irregular pressure, try taking the belt and all gears offand turn by hand.

 

Can’t see it being a chuck problem if it does it on both chucks and the faceplate

 

Jason

[Stephen RowleyParticipant @stephenrowley13300]

I will try what you have suggested but will have to buy the dial gauge this weekend and a MT3 centre.

If the spindle is out the chuck only fits on to points on the spindle. one is a band parallel on the spindle and the other is a step.  If both of these run out and I face them off square once more would that make it come back true.

I think I will add a Photo later so you can all see what I mean.

James

[Stephen RowleyParticipant @stephenrowley13300]

I was up bright and early this morning as there  was something I needed to try.  I removed the back plate from the chuck turned it round and screwed on to the spindle and that made the error worse even though it is another machined face.  so, have I been unlucky to get a chuck, back plate and four jaw chuck were the fitting has been made out of true ?

James.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi James, even if the backplate was running true the correct way round, it is unlikely to run true back to front as they don’t have a true registrar on the front to fit the spindle nose. Regards Nick,

[Stephen RowleyParticipant @stephenrowley13300]

I would like to thank you all for the good advice.  One thing I forgot to correct is that the replacement spindle was a second hand one and with a laser shining on the spindle and can see that the replacement is also out.

 

In an act of desperation I re fitted the chuck and put a gauge bar in and then with a new tool put a mark at the highest point then with the assistants a peace of oak and a 1/2lb hammer gave the spindle a smart crack. I then spun the gauge bar again and to my amazement the high point had moved and was  worse.

 

My next idea is to look at the adverts for someone who could make me a new spindle out of better quality metal    or buy a new lathe.

 

I am now going to console myself at the Malpas Steam rally just up the road in Cheshire..

Once again thank you all for your help and advice.

 James

[Keith LongParticipant @keithlong89920]

Hi James

I’d be surprised if you need to get a new spindle made or change the lathe to solve your problem. If the headstock bearings are the same as the 920 then they are tapered rollers. The fact that giving the spindle a smack with a small hammer has caused movement suggests to me that something in the bearing system is not seated correctly. If the bearing outer ring is not located correctly that should give you an axis misalignment and if it can move variable run out. If the inner ring is not seated on the spindle shaft then that could give rise to variable run out under changes of loading – giving it a smack with a hammer. I think you need to strip the spindle and head stock bearings down and start from first principles. Are the bearing seats clean and undamaged – there might be burrs. Are the bearing rings seating correctly when you enter them ie are they fully home and correctly aligned? Is the spindle itself straight? Are the bearings correctly adjusted – taper rollers (opposed) should give a very “rigid” bearing system (I don’t mean tight to turn) – thats what is often used in car wheeel bearing systems, about the same diameter bearings and those have to put up with large shock loads and “overturning” loads from steering. Trying to diagnose the problem from “outside” by swapping bits around and tapping with a hammer won’t do it unless you are VERY lucky. Basically if you can affect things with a half pound hammer something ain’t right – your cutting loads will cause everything to shift.

Keith

[Sub MandrelParticipant @submandrel]

I vote with Keith.

 

The hammer treatment is not a good idea, even if you get it straight, you will be storing up stresses for later.

 

You really need to check the bearing’s adjustment first.

 

Neil

[Billy MillsParticipant @billymills]

Is there a crack in the headstock casing?if it has cracked then the bearings would move apart slightly under the preload. There may be some adjustment to preload the roller bearings, might be a selected distance piece on the spindle. Manual needed!

 

Would try mounting a dial by the toolholder  and then putting the plunger onto the face of a chuck, apply hands to the chuck and see what the deflection is when you apply force to the axis of the spindle.  Would then try same at 90 degrees on the side of the chuck and then on top to get an idea of  what movement might be there. Similar variations on the three axis would suggest no preload on the taper bearing. But don’t use that hammer yet!

 

regards,

Alan.

[Keith LongParticipant @keithlong89920]

Hi JSK

You have a message.

Keith

 

[Stephen RowleyParticipant @stephenrowley13300]

I had a friend call today (Monday) who plays with lasers and he put a mirror in the MT of the spindle and when we started the lathe instead of getting a dot of light fro the laser we had a circular beam which over a distance of 12ft showed quite a marked discrepancy.

I am going to put the old spindle back and order a dial gauge as the one I  though I had was lost in the fire.

James. 

[John OlsenParticipant @johnolsen79199]

Well, you are making progress anyway. When you take things apart you should be looking at things very carefully. This is a lathe with some sort of rolling bearing, right? For it to be turning eccentric, it seems to me that there must be a problem between the spindle and an inner race, or maybe in the race itself. If the problem was between the outer race and the housing, the spindle could be out of line with the bed, but should not rotate eccentricly. So  either the spindle has to be bent as you first suspected, but that seems unlikely when you have tried two, or there has to be a problem that means that the bearing race is not properly seated on the spindle, or else maybe the bearing has some play. Not being familiar with the particular arrangement, I’m not sure how that could come about, but I would be looking for things that might cause that. If the bearing was not set up properly you might get play, but that would be erratic as it moved within the available clearance.

 

regards

John

[BogstandardParticipant @bogstandard]

If it has tapered spindle bearings, have you correctly set the preload?

 

If not, the spindle could be positioned almost anywhere.

 

Belting with a hammer wouldn’t have helped at all.

 

Bogs

Edited By Bogstandard on 14/09/2010 11:17:08

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