MC900 off center

[vk4]

Hi All,

i have brought an MC900 from E-BAY, the lathe is only 10 months old from new, the previous owner used it for around 4 hours , and found it took too long to make things , so sold it.

I have found that the main shaft is 0.5 mm out of center:(, and as it is 2nd hand the importer (HARE&FORBES) WILL NOT HONOR THE 12MONTH WARRANTY.:((

DOES ANYONE HAVE ANY SUGGESTIONS AS TO A QUICK FIX?:rolleyes:

I have priced a new shaft $60.00 delivered, so I may have to go this way, but i would prefer to look at alternatives as well.

Jeff
vk4

[Big Shed]

Hi Jeff and welcome to the forum.:2tsup:

When you say "off centre" I suppose you are referring to runout? If the spindle is indeed off centre then replacing it won't necessarily fix the problem.

If it is runout then I'm afraid to say that is not an uncommon thing in wood lathe.I at one stage bought a mini lathe and it also had unacceptable runout, but the suppliers' response was that it was "in spec". See here (http://www.woodworkforums.com/f69/bought-new-mini-lathe-110151/).

Some questions for you:

How did you measure to establish the off centre amounf of 0.5mm, and where did you measure this?

Are you perhaps referring to the sindle and the tailstock not lining up?

Did you measure this on the actual spindle, and if so where? Or did you measure this on a centre inserted in to the spindle?

Of course H&F had the perfect "out" on the secondhand angle, but I have a sneaking suspicion they would have had another excuse if you were the original owner, something like "it is in spec"!

[bellyup]

Hi Jeff and welcome aboard!!
When you say the alignment is out .5mm, I assume you mean .5mm too low?
If that is the case, you might be able to insert a shim under the foot/feet of the tailstock - most of the MC type lathes are pretty "generous" in their fit.
Having said that - .5mm is not a great deal in a wood lathe, in a metal lathe it would be unacceptable. Sure, perfect would be great but .5mm out is not unusual.
Bruce.

[vk4]

Falco,

Hi thanks for replying so quickly.

I turned several small bowls initially, and found that when the work was reversed on the lathe that it was off center.:?

I then took a piece of timber , turned it to a cylinder , then taking a 6mm parting tool turned a square groove this established a datum to work from,. The next step was to loosen the scroll chuck and rotate the cylinder 180'deg and re-tighten. I then cut another groove , I then measured the depth of the groove the first groove varied by 0.04mm, the second groove varied by 0.5mm+.( The tail stock and live center was used to stabilize the outboard end both times)

This seem a crude method and may not be perfect , but it does give a reasonable indication as to the run-out of the shaft.:2tsup:

Jeff
vk4

[Big Shed]

This seem a crude method and may not be perfect , but it does give a reasonable indication as to the run-out of the shaft.:2tsup:


Yes it does, and no, it doesn't:no:

All it does tell you is that there is a difference between the 2 grooves.

There are a number of variables here, of which the shaft is only 1.

Shaft, bearings, scroll chuck, scroll chuck insert (if any), scroll chuck jaws, the pressure on the parting tool and it's position, I could go on.

About the only thing I am almost sure of is that spending $60 on a new shaft won't fix whatever the problem is.

Just the fact of taking a piece of wood, of variable density, out of a scroll chuck and remounting it at 180deg can, and probably will, give you that sort of result. In fact you could get that by taking the wood out and re-mounting it in the same position on the scroll chuck.

The amount of pressure used to tighten the jaws again will give you a variation.

There are any number of threads here from people complaining about run out on their scroll chuck, usually caused by a crappy insert.

In your position I would start measuring the shaft run-out, both outside and inside, with a dial indicator as I have shown in my link above.

I would record all those readings, if there is run-out on spindle OD, I would look for play in the bearings first and finally consider replacing the shaft.

If the shaft is OK the next step would be to mount the scroll chuck and measure the run-out on the OD, then mount a piece of bar, preferably silver steel, in the scroll chuck and measure the run-out on that.

If there is run-out in these measurements, I would unscrew the insert and mount it on the spindle and measure the run-out on it.

By this stage you should have narrowed down where your run-out is, if indeed it is caused by the machine and not other factors such as re-mounting timber, variations in using the parting tool etc.

Hope that helps.:2tsup:

[vk4]

Falco,
I will have a talk to a couple of friends and see if I can lay hands on a dial gauge , and see what I can see with it.

Thanks for the advice,:2tsup:
Jeff
vk4

[vk4]

I have found a dial gauge and mag base that I can borrow:), and I will check the shaft , insert and chuck ,. if necessary I will remove the shaft and get it checked by an engineer.

Cheers,

Jeff
vk4

[orraloon]

Jeff,
I think Big Shed has pointed out most of the things to look for. As you are getting a guage then check the shaft first. I would only be worried if the shaft was out enough to be spotted by eye. Bring up the tail stock with centers attached and have the points almost tutching. This will show if the alignment is good. 0.5mm with this is livable but shims can correct this. Next run at a low speed and if the shaft is out the center point will describe a circle around the tailstock point. It is common to have some runout with scroll chucks, even the best of them. If the shaft is close enough then the problem is the chuck and or the threaded insert. Often just cleaning the threads of the insert,chuck and shaft can help this a bit. It has been my experience that any time a bit of wood is remounted on the lathe then it will be a little bit out. I expect this to happen and plan a job around that. Usually a bit of trueing up is needed.
Regards
John

[hughie]

I am surpised that 0.5mm is an issue, my old MC1100 was out all over the place. But the moment you re-chuck a piece of timber you can pretty well gaurantee it wont be true and if its re-chucking with .5mm out of true, your doing well.

But if your going to test the eccentricity, then do it on the shaft at the register with the chuck off and then re-do it with the chuck on and compare. This will let you know if the insert is out etc.

I spent some time sorting through the more glaring problems, such as lousy headstock lock on the swivel, fully flexible stand :U No nylocks to the various locking nuts etc. I left the alignment as it did not really effect my bowl making, if I was doing pens it might be an issue.

Gave it away to a mate who hasnt had any problems with alignment, but again he does bowls only.

[vk4]

Thanks for the replies , I am still wary as i have just mounted a platter and turned the bottom and outside, and remounted in the scroll chuck, .to do the inside and outer edge.

I will be looking at all the aspects of the lathe :), and see how I go, I cannot get the dial gauge until tomorrow morning, should know some answers by tomorrow afternoon.:2tsup:.

Cheers

Jeff
vk4

[joe greiner]

I'm with hughie to some extent. Half a mm doesn't seem like a deal breaker.

I have two copies of (almost) that lathe - Harbor Freight 34706, but as yet, I don't have enough real estate for both of them. While overhauling one of them, I swapped headstocks, and tailstock alignment went into the weeds. For a Q&D remedy, I place a tongue depressor (~1/16") under one side of the tailstock, and alignment is close enough for drilling vases.

Even in a perfect lathe, reverse mounting is hard to attain real concentric conditions. In the metalworking industry, if perfect concentricity is needed, a single mounting is usually specified.

Cheers,
Joe

[Paul39]

I'm with the above mob that contends that .5mm is nothing to be concerned about.

If you turn something in the evening to dial in perfectly and leave it to finish on the lathe, by morning it will be much further out than .5mm.

The round will be oval and the rim will move to and from the headstock.

Wood moves, even theoretically dry wood.

I use both wood and metal lathes, I have never put a dial gauge on any wood lathe.

Assuming a "dry" blank, for the least amount of error with bowls and a scroll chuck, I mount the blank on a faceplate or chuck, top toward the headstock.

I semi finish the outside and make a very clean and precise spigot or recess for the chuck.

I remount the bowl, carefully fitting the jaws to the spigot or recess and make a mark on the bowl at the center of the #1 jaw. This is in case I must remove and remount the bowl. It will not run true if remounted, but will be closer (maybe) than if put on randomly.

I then hollow and finish turning, sanding, and finishing everything I can reach without removing the bowl from the chuck.

If this takes several days the bowl will move.

I then remove the bowl and use a piece of medium density fiberboard mounted to a faceplate, with a groove cut to fit the rim of the bowl (jam chuck) with blunt wooden live center holding it on to finish the spigot or recess. I then remove the bowl and hand finish the bit under the tail center.

Some use tape to hold the bowl on, which leaves the whole bottom free.

There are Cole jaws to hold the bowl by the rim to finish the bottom. I have found that the bottom of the bowl orbits quite a bit. I bought the jaws barely used, but even at almost half off I could have spent the money better elsewhere.

After the bowl has sat around the house a week or so you may notice that it rocks a bit on the bottom.

Tape a piece of 220 grit paper to something flat - table saw, piece of plate glass, plywood, - and holding the bowl firmly down, give it a few strokes going with the grain. When it sits flat, do the same with 400 grit and refinish the bottom.

[vk4]

HI Guys,

Well I got the loan of a DIAL GAUGE today, I sst it on the lathe bed and after removing the chuck, and insert, I checked the Lathe shaft, .003 run out:2tsup::2tsup:, outside, inside .002:2tsup::2tsup:

I then mounted the chuck insert, that was .015 -.020 variation,:rolleyes::rolleyes:,

I then mounted the chuck (vicmarkVM100) the body was measured just behind the JAW Grooves, and measured .020 out , I then moved out to the actual chuck jaws, these showed the greatest variation at .030-.038 , ..

So it appears that the issue falls to the Scroll Chuck and Insert , the actual lathe is not the issue as I first thought.

I have contacted Hare & Forbes an advised them that I have found the issue is not the Machine /Lathe , to do the right by them.


Thanks for all your assistance ,

Jeff
vk4

[Big Shed]

That saved you $60 for a new spindle and a fair bit of work:2tsup:

Actually, what you proved there is that taking a piece of wood out of a chuck and remounting it, either at 180 deg or in the "same" place will give you some runout.

I assume the dial gauge was an inch one?

[vk4]

HI Falco,

Yes it is , I checked the M2 drive spur as well and there was only .003-.005 run out on it as well. :2tsup:

Also happily the tail stock live center and drive spur , line up nicely , so over all I am very happy.:2tsup::2tsup:

Many Thanks for your advice , I have managed to acquire a good quantity of Camphor Laural , both green and seasoned , along with a small block of Huon Pine, some Grevillia, and a couple of species I don't know but the blocks are seasoned and still weight a ton, :D.

So I have a good basis to work with.

anyway cheers for now ,

Jeff
vk4

[Mrs Blackie]

Hi vk4, I have the same lathe you will have to excuse me as I am on antibiotics right now and might have missed some of what our fellow members have said but I just wanted to remind you that our headstock is a revolving one mine sometimes is out and a quick fix for me is shake shake shake if it moves I re align it and tighten it then bring the tail stock over to see if it is out or not, I just hope we are talking about the same thing here, am a bit slow tonight. But try that and see.:)
Cheers!

[vk4]

Hi Mrs Blackie,

No the lathe head stock is fine and in alignment:2tsup:, the problem is with the insert and chuck,:(
I have worked out how to over come the variance:) , so will see how it goes.

Cheers,

Jeff

[hughie]

No the lathe head stock is fine and in alignment:2tsup:, the problem is with the insert and chuck,:(

,

Jeff, I have found in the past that its invariably the insert, especially if you have bought a known brand of chuck.

[vk4]

Hughie,

Yes the vicmarc is a good chuck:2tsup:, and came with an insert from VERMEC , I don't know if Enzo makes his own inserts,:no: but I doubt it,

Jeff

[mimpi]

I had a very similar experiance with a hare and forbes new lathe matching a supernova2 chuck and insert. I ended up padding out the thread between lathe and insert with plumbers tape and it ended up giving me near perfect runnout.

[vk4]

Thanks, I will give that a go today.:)

The joys of being retired:D, we were fishing in the boat yesterday.:2tsup:

Jeff

[socratous]

Hi All,
I have found that the main shaft is 0.5 mm out of center:(, and as it is 2nd hand the importer (HARE&FORBES) WILL NOT HONOR THE 12MONTH WARRANTY.:((


FYI only cars and houses carry the warranty on to someone other than the original purchaser. You could have bought that lathe 3 days after the original purchases bought it and the warranty would still be out the window :(

[vk4]

Yes also the same for caravans , no warranty on second hand either,.

Any way I have thoroughly checked the lathe out:2tsup:, and found an issue with the CHUCK:oo:, which I brought NEW, I took this back to the supplier and it was fixed immediately :2tsup::2tsup::2tsup:.

So I now have all working as they should be.

And i am now making some sanding jigs etc.

cheers,

Jeff