Runout in spindle face plane

Please excuse what may be daft questions - but I am completely new to engineering having bought a WM250V lathe and WM16 milling machine. I had no background or association with any engineering profession, therefore no metalworking experience although an experienced woodturner. I hope to build model engines as my retirement hobby.

The lathe inspection sheet indicates that the spindle face plane has a permissible tolerance of 0.015mm runout. However, when I measure this using a dial test indicator I find an actual runout of 0.028mm as opposed to the testers recorded value of 0.005mm!

My questions are 1) Is this amount of runout acceptable? 2) If not what can I do to bring this into acceptable levels - I assume the spindle face is hardened and in any event I cannot see how I could get any cutter close enough to the face to machine it ( the leadscrew covers prevent me from getting anywhere close to the spindle face).

Any help appreciated.

Charles

If this is a brand new machine that has been set up for you then stick a bit of metal in it and see how it cuts?

If you start to mess with the machine itself then your warranty could be voided

Other Warco users (not me) will give you advice on what "safe" tweaks you can make, (a teeny bit more preloading on the spindle bearings for example may solve all your trubbles)

If you have never cut any metal at all before now then it's a bit early to start cutting at any precision parts on the machine itself

Edited By Ady1 on 28/08/2017 09:15:28

Significant error here is rarely caused by a machining error. Three things:

1. The lathe will have been tested at a factory held down on to a large, very solid bench. Unless you have it supported in exactly the same way you are unlikely to get exactly the same reading.
2. Check the spindle bearings are properly adjusted.
3. You have to be sure you are taking the measurement off the surface the chuck mounts on.

Neil

Pop the face plate on and check the run out at the outer face. I would not worry about a thou or so (0.025mm in new money). Most of your work will be sub 50mm in diameter and doubtful if any error would show. I retire now to get shot down by the "Tenth Chasers"

Edited By Chris Evans 6 on 28/08/2017 09:50:28

Thanks for the swift responses - as you can imagine I am in something of a panic !

I understand that I don't have the same degree of bench / measuring equipment - but the bench is constructed of 100mm x 100mm timber with a 40mm thick top - and 12 levelling feet, hopefully this has allowed an accurate set-up.

I have no idea how to check if the spindle bearings are properly adjusted - the Warco manual has no reference to this at all - any insights appreciated.

I have taken measurements from the spindle face in multiple places - the run-out of 0.028mm is pretty consistent - the run-out on the 'nose' itself is better (polished surface) but still 0.02mm out.

I have also taken measurements with the chuck backplate fitted - even worse with a runout of 0.075mm on the face and 0.13 as a radial test.

Strangely, a radial test of the chuck body fitted shows a better reading of 0.08mm?

Finally, I fitted a piece of 25mm silver steel rod and measured runout at 50mm from the chuck jaws - this shows a runout of 0.20mm.

When I turn any diameter of rod I see that it marks on one side only until I make a significant cut - to me, in my ignorance, this would indicate I have a serious problem? I have checked the jaws / scroll etc are meticulously clean.

Once again, any advice much appreciated.

Charles

Sounds like you should contact the supplier. If it does not meet, or come close to, the inspection certificate it has been sold in not fit for purpose condition.

Your 25mm bar would be better clocked and gripped in a four jaw, No three jaw is perfect

Roy

Can you post a picture of how you are making the measurements?

Hold a decent length of bar in the chuck. with one hand on the headstock and the other on the bar can you feel any movement? If you do this with a DTI sat on the lathe bed and touching the spindle nose, how much movement to you see?

Almost every example where people have 'out of true' spindles turns out to be poorly adjusted bearings. These tests should give a clue if this is your problem.

But certainly, seek Warco's advice before doing anything other than make adjustments or writing off the machine.

Neil

This is the test Neil is describing to see how much play there may be in the spindle, I'm pulling and pushing that bar as hard as I can. the imperial dial equates to about 0.012mm movement

Edited By JasonB on 28/08/2017 12:20:08

And this is how to measuer the runout.

My 280 gives 0.007mm on the flange face

0.013mm on the spindle spigot

0.006mm inside the taper

Well I have never read a thread (pun intended) which does not address the real issue. Charles as a newbie you are probably convincing your self that your machine is inaccurate or faulty. What matters is not any reading that you get from the outer diameter of any spindle mounted accessory like a 3 or 4jaw chuck, or faceplate. The only thing that matters is the accuracy of the work that you produce. So put your bit of silver steel, or a mild steel bar or a piece of aluminium and reduce it from its nominal diameter with a clean cut all round. Then measure the diameter you have created. Then apply attest cut of say .020 inch (0.5mm in the Napoleonic measure) and then re-measure. That will show you how accurate your machine is when removing metal Before taking the first cut, put your DTI on the bar and rotate it by hand and note the readings on the dial. Repeat after the first cleaning cut, and again after the test cut. By noting the diameter and the clock readings you will find out whether your machine cuts correctly. Remember write down the readings do not try and remember them. Do not run the test bar as shown in the video's. At the speed shown you may get bounce in the DTI and thus create apparently higher readings. Hope this helps, as you can practice cutting, measuring and establishing run out all in one exercise.. Please let us know how you get on.

Gentlemen,

Thanks again for the support.

JasonB - your videos much appreciated - fortunately I was doing exactly as you were. I've now obtained a supposedly much better DTI (Jewelled no less) and remeasured with the oversight of a local engineer who knows much more than I do.

Flange face - runout 0.35mm (formerly measured by me at 0.28mm) - spindle hand-turned using the drive belt - spigot face not polished, obviously ground as you can see the striations.

Spindle spigot - 0.008

Inside the taper - no discernible movement

Dead centre in the taper - again no discernible movement measured from the angled face.

In essence the flange face is the culprit in my view and I cannot see how this can be easily corrected.

I also tried putting a large wooden dowel in the spindle and pulling / pushing whilst the dti in position - no movement - mind you I'm getting weak in my dotage.

I appreciate what you say MadMike - but if you buy a machine with a test report which says spigot runout tested at 0.005mm / max permissible 0.15 and in reality it is way above and beyond that it does little to instill confidence in the quality control / honesty of the Chinese tester - I'd like to think you get the quality specified and paid for in a new machine.

As a novice I need to be able to discount machine error so that I can be sure any failures are mine and mine alone. I have now turned a piece of brass rod in the three jaw chuck, lovely finish but the 'wobble' was evident even in a 100mm length - the cut diameter less at the jaw end than the tail stock end.

I should perhaps make it clear that I am an experienced wood-turner - i believe I can see more accuracy in my wood-turning lathe!!

What can I do - there has been reference to the bearing adjustment - how do you approach this?

Charles

Talk to Warco tomorrow.

However as the faceplate and chuck backplates can all be trued once in place you may want to go down that route. Provided they are always mounted as per the "0" marks then they can be turned in situe to have minimal run out. The chucks can be mounted on the trued backplates and will run a lot better.

If you can't wobble the spindle I would not try adjusting it at the moment. If you had got a reading on the DTI then it would be worth adjusting.

Edited By JasonB on 28/08/2017 17:13:14

Will do - emailed them last night.

I understand about truing up the backplates - another stupid question - how can you do that when you can't bring the toolpost / tool near enough? The leadscrew covers prevent me getting anywhere close.

I'll measure the 'gap' tomorrow if I haven't resorted to a lump hammer before then!

Really want to make a model engine to pass on to my grandson - got plans for a Stirling 60 and castings for Perseus.

Thanks again.

Charles

Hi Charles,

On my lathe I have the same problem as you, the leadscrew cover prevents me from getting close enough, so I use a sturdy boring bar for such jobs. You can mount it upside down and run the lathe in reverse, just make sure the cutting edge is on lathe centerline.

Thor

Hi Charles,

Definitely speak to Warco but check your figures first, you state 'the flange face - run out is now 0.35mm (formerly measured by me at 0.28mm) maybe .028mm as per your first post? I have just noticed Warco actually test the lathe so they can explain what is going on.

Good luck, keep us informed.

Tony

My figures should read 0.035mm runout formerly 0.028mm - i.e. 1.4 thou by measurement with my new dti.

Apologies for any confusion.

Thor - strangely enough I had thought of the upside down boring bar - discounted it as a mad idea. Delighted to hear it may well be feasible !

I assume the flange hardened and a carbide tipped tool a necessity - any suggestions for spindle speed, feed rate and minimum depth of cut that could be taken - I'm not sure I have the skills for this kind of operation - speak about being thrown in at the deep end!

No don't touch the flange

The faceplate and the chuck backplates are soft so can be trued but only if you have no luck with warco.

Charles I have seen your reply to me about the piece of brass you turned. However at what point did you observe the "wobble"? Was it before you made the cut? Did you measure the diameters you produced and measure the run-out on the turned piece as I suggested? If you did then what readings did you get?

Edited By MadMike on 28/08/2017 23:26:49

Mike,

Any piece of bar held in the 3 jaw chuck shows an obvious runout ('wobble' in my terms) - even a piece 100mm in length. I put a dti on a bar at 50mm from the chuck jaws and got 0.22mm runout at the end of the bar - i.e. 50mm in the jaws 50mm out. Tried with several bars just in case - all with very similar results.

On first cut you can see it cleans one side of the rod only.

Unfortunately, I haven;t as yet followed your instructions to the letter - I will do so today with a piece of aluminum - acquired a micrometer (only had digital calipers before) so will check the cut / diameters at various points.

The lathe has factory fitted DRO's - haven't yet sussed how to use the Sino control unit - will have a go at that also.

Just a little concerned about using the lathe at all in case I jeopardize any case I might have with the supplier.

Just waiting for them to open.

Your support much appreciated.

Charles