ML7 set up

[WokaukParticipant @wokauk]

Have read sites on the web about setting up a lathe.

I seem to have failed at the first hurdle.

My lathe does not cut parrallel, it cuts a taper 8 thou mm in diameter difference over 4" mm. The smaller diameter at the chuck end. This taper was cut using the tail stock.

The sites I have looked at suggest that I put a 1" bar in the chuck and turn two collars approx 8" and compare the difference in diameters. I have a length of 7/8th dia 10" long. that I thought I could use. (mild steel)

Trouble is I cannot cut it, I just get awfull vibration regardless of the tool I use or the revs or the depth of cut I tryed 1 thou awful, briefly tried 5 thou hit the emergency stop in fear due to noise. Is it expecting too much of an ML7 to cut something like this? With the support from the tail stock it cuts lovely, but you should do this exercise without the tail stock?

This ML7 is I suspect well worn, so ultimatly I suspect the taper is due to bed wear, however I would like to find out for certain by setting the lathe up properly to start with.

The lathe is mounted on a very solid solid bench (though wood). I have made some mounting blocks and have levelled the lathe as best as I can using a buliders 2ft level.

I was hoping to get the two machined collars the same by altering the heights on the mounting blocks to compensate but as I can't machine the collars……….

Getting hold of the 10 inch bar when secured in the chuck and heaving on it does not highlight any play in the head stock.

To me a total beginner machining something with an 8" overhang would seem too much for my small lathe.

Any thoughts.

[WokaukParticipant @wokauk]

[John Stevenson 1Participant @johnstevenson1]

5" is enough, no need to stick it out 8"

What you need to do is machine 2 collars with a recessed in between.

Nothing to stop you doing this using the tailstock for support and rough out.

Then remove the tailstock and take a couple of light skims over the collars to clean up at the same setting prior to measuring.

[JohnFParticipant @johnf59703]

Look at your messages

[Anonymous]

I'm a bit confused over units, do you mean a difference of 8 thou in diameter over 4 inches? I think it unlikely that bed wear would cause such a large taper. If it was responsible, then the saddle would be very obviously loose.

My first thought would be that the tailstock is not aligned with the headstock. If machining a test bar without tailstock support still results in a taper then I'd consider a twisted bed. A builders level is way too insensitive to measure bed twist. In the absence of a precision level then machining a test bar is a good way of aligning a lathe. It's disadvantage is that it doesn't discriminate as to the cause of the error, so you may in fact end up twisting the bed to compensate for other errors.

An indication of where you are would be useful; there may be somebody close by who would be willing to help hands on.

Regards,

Andrew

[Rufus RoughcutParticipant @rufusroughcut]

Hi Wokauk

I've just recently revived an old ML7 where I found the tail to head stock to be out of line with each other, now I presumed that most of the wear or misalignment would be within the 8" or so from the head stock so I removed the chuck and fitted a small tail stock drill chuck in both tail stock and head stock spindle bore then tightly fitted a sewing needle in each of these, then brought the tail stock up to the head stock keeping a short distance between the needles (the distance really is immaterial at this point) having locked the tail stock at this point I advanced the tail stock chuck with needle fitted towards the head stock needle using the tail stock hand wheel in the hopes these looking through a magnifying glass would now meet point to point, which they did not the tail stock needle passed in front of the head stock needle, which was really obvious when I looked from above, from this I presumed that the tail stock needed adjusting inwards, so I back up the tail stock hand wheel until both needles appeared to be almost touching and adjusted the tail stock adjusting screws, by taking some of the pressure from the tail stock lock and undoing the far side adjuster screw a little and tightening in the front (near side) screw until the needle moved in line with the head stock needle when viewed from above, I re-locked the tail stock down, and check the travel alignment again, at which point the two needles points touch without any deflection from each other, I then screwed back in any slack on the rear adjuster screw, I then released the tail stock lock, moved the tail stock back to allow me now to almost fully extend the tail stock out and then slid them towards each other again leaving the last hand wheel wind to bring the needles together again, which they did. so before I get burned at the stake. the area along the bed nearest the chuck when fitted as far as I'm concerned where most of the cutting tends to take place was aligned head stock to tail stock across the bed at a needle point dead centre to each other, I then without removing the needles, set a cutting tool in the holder to the point of the head stock needle and locked it in the holder, I then moved the tail stock back along the bed ( say 10" or so) and wound the hand wheel back in and locked it down, I now traversed the saddle down the bed to see where the set cutting tip met the tail stock needle, these met tip to point, so that's me happy now to test cut, having refitted the tail stock centre and the chuck. to make a test cut I would need a bit of barstock which could be any length you like 4", 6", 8" whatever of a diameter that could be inserted into the chuck as far as possible to a make clean cut off end and centre drilled as near to the chuck as possible on each end of that barstock, I then extended the bar out of the chuck 1" or so and made a light cut to parallel the bar ends ( to the chuck (material rotation and holding point)), I then fitted that bar in the chuck and tail stock and was able to now make a known test cut at each end of the bar and re-check the cut,

At this point blethering aside I have only used a pair of needles, a Sherlock Holmes (non authentic) magnifying glass and a bit of bar to align, two point about which the bar is to rotate and set the cut height of the cutting tool to cut along between those two points, I found my lathe to now be 0.00025 out of true over the whole available working length of the bed.

In your case widening at the tail stock end would indicate the tail stock needle would need adjusting towards you rather than away (in my case), bed wear this far down the bed from the most used area near the chuck seems a bit unlikely although I'm about to be burned at the stake again, If all the bolts at the motor, head stock and head stock end of the bed are fully secure and belts are running true then the vibration would probably be due to, gibb strip being to too loose in the guide ways of top/ cross and or saddle.

Hope my Blethering helps and I'm certain you'll get any amount of advise all be some of it expensive options.

My ML7 is 1954 fixed to a bit of 2" work top bench and I don't know if that's level so don't get drawn into the spirit level paradox. Try the above which has no real cost first.

Barry (flame on)

[Sub MandrelParticipant @submandrel]

I'm more worried worried about the screeching. At 7/8" diameter even my mini lathe would happily take a 20 thou cut in mild steel.

It certainly sounds like something is loose somewhere, more than just wear.

Neil

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi W ,

An ML7 is a simple relatively rugged lathe for its size and it will at least basically function under all conditions of wear .

Most likely problems you have are :

(1) That there is no oil at all in headstock bearings – old ML7 oiling system can block with old oil gone to varnish . Flood oil in through cleaned pots and just slosh some over bearing ends .

(2) That your tools are not cutting at all – just rubbing . Causes are wrong shape , not sharp or mounted above centre height .

There is nothing magic about a tool for simple turning – if it looks like it would cut and is sharp in the simple sense it will work – well enough to get started anyway . Best to keep the part of the tool in contact with the work small to begin with .

Having a tool mounted above centre height means that in most cases it will not work at all . Line up cutting edge of your tool with centre in the tailstock and if you are not certain then leave tool a little low – a slightly low tool will cut far better than a slightly high one .

Where do you live ???

Michael Williams .

Edited By MICHAEL WILLIAMS on 19/04/2013 10:43:55

[WokaukParticipant @wokauk]

Thanks for advice off everyone, I shall try the knitting needles.

I am In Malvern, Worcestershire.

I am sure I have the the correct tool height. Tool sharp, I don't really have the experience to know if it is or not, I am pretty sure it would cut me!

There does not seem any obvious play anywhere, but I will check again.

Seems like I should solve this cutting problem before I even think of tackling the taper.

I am away this weekend, so cannot get into the garage to play.

Thanks again,

Woka.

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Malvern is too far away for me to visit but there are lots of home workshop people in that area so perhaps someone closer to you will volunteer .

Get you lathe to do simple turning satisfactorily before worrying too much about alignment .

[speelwerkParticipant @speelwerk]

Do also check if the headstock spindle is setup correctly, if it has to much play (axial and/or radial) and you cut without tailstock support 8 inch away from the chuck, you will get serious vibration. As allready mentioned 4 inch apart is enough and should be no problem. Niko.

[Ian S CParticipant @iansc]

Is the chuck worn, it may be only gripping at the internal end of the jaws. Ian S C

[WokaukParticipant @wokauk]

I decided that that there was slight play in the headstock bearings, strangely not at the chuck? Took the bearing cap off to reveal a combination of the laminated shim and other bits of packing. One side had 5 thou more than the other. Why would this be?

I packed up the caps in 5 thou invetervals until it was too loose (25 thou). Replaced one of the 5 thou shime with a 1 thou shim and I got a nice fit with no play. Both sides at 21 thou total. Does this seem a normal figure?

think ishould check out the other bearing, but I cannot detect any play in that.

I checked the run out on the chuck register it is it is half a thou TIR.

My cutting has improved unsing the same tool and piece of bar, it took a 15 thou cut at 4 inch from chuck without too much complaint. Crap finish though. 5 thou gave a nice finish.

I am pleased with the progress so far but should I expect better cutting performance than this? Or can I now look at the bed alignment?

I suspect that the lathe will still cut a taper, but I haven't checked yet.

Thanks for advice so far, it is much appreciated. It so difficult to distinguish between my lack of ability and problems with my tools, there is a saying about that…………..

Regards,

Wokauk

[SpannaParticipant @spanna]

has anybody suggested a lathe setting bar yet. They are expensive for a one off job, but its the only way to be sure.

It has the taper to ensure the head is straight and centres to check the tailpost is in line

Chronos and others sell them.

alan

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