Turned items are not looking good ...

I have a Harrison lathe which has defintely got a bus pass and probably a free TV licence too

No matter how carefully I turn things it looks like rats have been gnawing at it. As far as I can see there are 3 possible explanations

1. I don't know what I am doing

2. The tools are blunt

3. The lathe is knackered

Or all three

Any suggestions as to the best way forward?

Bob

The age shouldn't be a problem I started with a lathe about 100 years old. If it's knackered you can fix it/get round it.

Your numbered points:

1. Fixed by asking here.

2. Try rubbing the cutting edge across the back of your fingernail. If it won't produce fine shavings sharpen it.

3. Make sure there isn't any play in the headstock bearings they should be tight enough so that without the drive connected if you spin the chuck by hand it won't do more than one or two revolutions before stopping. Make sure the gibs are tight enough. Is there any possibility of the tool movine in the toolpost or vibrating? Keep the tool tip as close to the toolpost as you can. Does the lathe vibrate much when in drive?

Hope that gives you something to look at as a start.

Russell.

Not familiar with this site so hope this post looks OK. Thanks for your help Russell

I have photographed a pic (Photo 1) of my best efforts done a few minutes ago. How does that look?

Bob

Hi There,

On my Harrison L5 I once experienced really ppor surface finish all of a sudden - the locking ring nut had vibrated loose at the back of the taper roller bearing at the front og the headstock and left excessive play - I made up a C-ring pin spanner and adjusted the locking ring nut and never had a problem after this. I had to remove the lid from the headstock of course and resealed the lid upon refitting with hylomar.

Hope this might help.

Neil

Is there an idiots guide to doing this anywhere, Neil? Or is this best left to competent people?

Bob

Hi Bob, If you need a handbook/partslist go to www.lathes.co.uk. Tony has quite a bit of info onsite

and sells a handbook for the L5. My own L5 is about 1960 vintage and works well, they are pretty bombproof if looked after . All the above advice is good but keep asking questions until you/we solve the problems. It sounds to me like you are cutting below centre and light cuts. Set the tool height by removing the chuck, fitting a good sharp centre in the headstock spindle and setting the tool to the point of the centre. Once you,ve done that and before removing the centre make a height gauge to sit on the bedways for future tool setting. It need not be anything fancy but must be accurate.

Nathan.

Nathan, this is my best so far ... is this what lead you to conclude I was cutting low and light?

Bob

Hi Bob,

I had a couple of different L5 manuals and I cannot remember them being that much help with carrying out fine adjustments. From memory on the lid of the headstock there are 6 or 8 cap head screws and I simply removed all of these and gently prized the lid off - you may have to cut the sealant to get it started to lift off. If you move the backgear lever into a central position it should release the spindle for free movement. At the right hand side of the headstock gearbox (ie the front end) you should see the bearing housing - should be a woven mesh filter on the top to strain the oil as it runs into the bearings. On the spindle just at the back of the taper roller bearings you will see a steel ring with about 4 holes radial round the OD - on my lathe these had been tightened with a hammer/punch - I managed to clean it up a bit and thats where the pin spanner came in - I tightened the nut until the bearings were tight to turn the spindle, and then backed it off a little bit at a time until the bearings were free but firm in running, and also smooth running too. I then refitted the lid - from memory I ran the lathe a short while under power but without sealant to make sure the bearings were OK. Then I sealed the lid up but didnt tighten the screws completely until 24 hours passed.

On the cross slide you should have a large chrome plated screw with a large pan type head - this screw head fit into a slot in the end of a tapered gib. advancing the screw into the cross slide tightens the gib, removing it slackens the gib. adjust it until the cross slide is moving smoothly but not too tight and not too slack.

I had bought the lathe and learned a lot by trial and error, but also found books like The Amateurs Lathe and using the small lathe very helpful.

Hope this helps,

Neil

Hi Bob,

If you face off the end of a bar do you get a pip left in the centre - if so your tool is set low - the diameter of the pip being twice the distance that your tool is below centre.

Neil

Hi Bob, Yes that photo is the one but I also wonder if your speed is too low. It,s also possible that you have a bit nasty metal in the chuck ! As Neil said you won,t get fine tuning info from the handbook but you will get speeds/ feeds/tool geometry and exploded drawings showing how things go together .

What are you cutting with and are you sure its sharp enough? The finish looks as though material is being torn out not cut . Resharpen and try again, we,ve all had to do that and it helps to gain experience .

Nathan.

.

No, I have got it right now - see my post above with pic in it

Regards

Bob

Bob,

Two things that haven't been mentioned are the type of tool you are using and the depth of cut. For example, if you use a carbide tipped tool and try to take a very fine cut you maye get a poor result as there is a tendency for the tool tip to rub. I find I can get down to about half a thou before this starts happening, but if the tool is just slightly above centre height this will happen sooner - and this isn't as easy to spot by the centre pip method. See what happens with cuts at various depths; if it gets worse for deeper cuts then it is more likely to be a bearing issue.

You will also find a great resource for advice on Harrison lathes on the Yahoo Harrison lathe group: http://groups.yahoo.com/group/harrisonlathe/

David

Edited By David Littlewood on 15/08/2012 20:03:38

I think you have hit the nail on the head there. I was hoping for an excuse to buy a new lathe but I think this is a case of pilot error rather than machine error ...

I will extend my range of tools, sharpen them and get them at the right height and report back in due course

Thank you everybody for your comments

Bob

I think I would look at the chuck as well. I don't think that has been mentioned, and if it has a bus pass, or not been looked after, the jaws may not be holding correctly.

Give the lathe a tune up (it probably deserves it), sharpen all and ensure you support the work properly too, with minimum overhang. But before despairing, mount a job in another chuck/collet/faceplate/4 jaw, and see. Culprit could easily be a dodgy 3 jaw.

Bob

Are you a member of the Yahoo Groups Harrison Lathe group? If not, I suggest you join.

http://groups.yahoo.com/group/harrisonlathe/?yguid=133995445

Dave

The Emerald Isle

One thing that hasn't been explicitly mentioned is the material type. Some steels (EN1A) turn like a dream, others (EN3B) can be a pig if the feeds and speeds are wrong. It can also depend upon where the steel was sourced; all suppliers are not equal.

Best Regards,

Andrew

I will keep it simple

You're just not trying

You're not observing the cut

You're not listening to the cut

Get it sorted

Get back to us in 12 months, after you've cut bucketloads of swarf

Don't look to anyone else, this one is yours.

A Harrison lathe is a major bit of kit

Edited By Ady1 on 16/08/2012 00:33:06

Oka-y

I'll take a couple of steps back (after falling out of the pub tonite)

How come you have a Harrison and you don't know what you're doing?

Edited By Ady1 on 16/08/2012 00:40:33

It's no different from women

How much can you learn from a book???

Dive in there and enjoy

My own Myford unit is 1944 btw

Edited By Ady1 on 16/08/2012 01:06:57

Hi I have been sitting back and watching this one, looking at the pics the 2 large bits of kit in what would look like a old school workshop, would also say that they are 3 phase. why the travel steady lying on the floor.
I would certainly go along with 1 and 2. as the lathe has far to much swarf around it to contribute to the example shown.

Bob.