New lathe arrived today : The ongoing saga

[AjohnwParticipant @ajohnw51620]

Posted by Brian John on 29/08/2015 12:21:05:

There was too much slop in the top slide : I have made some adjustments to the gib nuts now so things should be better tomorrow. I had not looked at that before. I probably got away with it on aluminium but not with steel.

NOTE : link to the '' men's shed '' has been blocked by my anti virus for some reason.

Edited By Brian John on 29/08/2015 12:22:10

The block is probably just down to the name. Obvious connotations and over zealous blocking.

John

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[AjohnwParticipant @ajohnw51620]

If you google Cairns none ferrous suppliers you will probably find some one that supplies aluminium locally. Very likely if there is some one who sells steel.

On simplicity you may find that one of your chuck jaw arrangements can grip the inside of the rim of the wheel so that you can machine the OD and one side in one go. In my view there is very little difference in taping a hole and slitting it for an expanding mandrel that running a die down some bar.

Few people would screw cut M6 or 1/4" by what ever. They would use dies. This is the sort of thing that is likely to be anybody who owns a lathe first major purchase. Screw cutting is used when this isn't possible. As far as dies go it's best to buy HSS split ones and taps to go with them. There are some very poor quality sets around. On taps money can be saved by just buying 2nd cut ones but on materials like stainless it would be better to have 1st cut as well. The other type plug is needed when tapping into a blind hole. When I started I bought individually as needed from an engineering supplier. The die stocks in sets can be a bit indifferent as well. It's an area where people tend to get what they pay for especially at the very cheap end. Good quality tool steel ones are ok as well really but most tend to be rather poorly produced.

I tried to find some web pages on screw cutting especially with your style and size of lathe which I believe doesn't have a screw cutting indicator but couldn't find anything at all. I did find a video that was using a mini lathe that did have an indicator for metric threads but that's not really suitable. Maybe some one else knows of one.

John

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[BazyleParticipant @bazyle]

You will find a die for this size is a bit difficult to use as it is hard to grip the rod tight enough to take the high cutting force so screwcutting is a good thing to master.
Stainless can be a bit hard and difficult to cut so stick to the silver steel.
But silver steel in its shiney new state is hardish. So cut off a short length enough for the job in hand and heat one end of it up to red hot in a gas blowlamp or cooker when the wife's not looking. After a minute or so hot withdraw it slowly so it gradually cools down. You can run a file over it and will see it is now softer. By heating only the end evenly it should not bend.

Mount it in the chuck with only about half an inch protruding to screw cut it. It is normal to work this close in so get used to it. We established earlier that the pointy first tool you were using is your screwcutting tool. Research on the web and youtube for screwcutting. There is no point in us giving the detailed instructions here. You will be looking for the offset or angled method, not the 'plunge method'. There will be lots of people now jumping up and down saying the plunge method works for me blah blah blah but ignore them. The old timers invented the offset method for the vey good reason that it works better on small lightweight lathes.
Do not try to screwcut under power. You will have to turn the chuck by hand. This is perfectly ok and I am still doing it on some of my lathes for which I still haven't made a mandrel handle (look that up and make one one day). Also you will only want to take a cutting depth of about 3 or 4 thou each time, and 1 thou towards the end. Yes it is slow but again ignore those who will say they take 30 thou cuts as they just want to boast that they were in industry with an elephant sized lathe turning battleship propeller shafts.

[Ian S CParticipant @iansc]

Brian, it might be worth your while looking up either the yellow pages, or the internet, there are quite a number of metal suppliers in Cairns.

For some work you can even make do with off cuts of rebar from a building site.

Ian S C

[HopperParticipant @hopper]

Posted by John W1 on 30/08/2015 10:55:07:

If you google Cairns none ferrous suppliers you will probably find some one that supplies aluminium locally. Very likely if there is some one who sells steel.

I missed the OP on this.

Brian, Norweld down in Portsmith on Ogden Street sells nice-machining ally offcuts of all shapes and sizes by the kg. Quite reasonably priced. It is "marine grade" which is as far as I can find out, 6061 or 70-something in a soft or medium temper. Machines beautifully. They are the only place in Cairns that sells offcuts. Ulrich Aluminium at Woree will sell you small quantities but at stupid high prices. Best place in Cairns I have found for small quantity steel is Tonkin Steel at Portsmith, unless you have found someone better?

[Brian JohnParticipant @brianjohn93961]

Thank you for all the advice.

Hopper : I have taken note of those suppliers and I will call tomorrow. Yes, I may need your help soon ; I live at Mooroobool.

Why would you want to lock the carriage in place ? Before I tightened this bolt up a bit there was movement in the carriage. Obviously tightening it up a lot stops it moving but a 1/4 turn removed the slight wobble it had. I was still having problems with getting a clean finish today. I am hoping that when I try tomorrow, things will be better now that I have removed all movement from the carriage.

I was warned by the company who sold this machine that it was not really suitable for steel and that it was better to stay with brass and aluminium. I was a bit surprised at this advice because it has a 500 HP motor. The Sieg C2 lathe which is a MUCH bigger 12 X 7 lathe only has a 250 HP motor. Are there other factors in play beside the power of the motor ?

I am using top quality HSS taps and split dies purchased from Arceuro in the UK.  I have found carbon dies to be rubbish. I am machining the 6.35mm silver steel bar down to 6.00 mm because I do not have any 6mm bar on hand at the moment. I will buy some 6mm aluminium bar instead as it should be easier to work with.

I regard screw cutting on the lathe as an advanced technique. If I am having trouble doing basic lathe work then I do not think I should be contemplating screw cutting on the lathe just yet  Cutting a 6mm thread on aluminium should be easier than cutting on silver steel.

Edited By Brian John on 30/08/2015 12:36:34

Edited By Brian John on 30/08/2015 12:59:00

Edited By Brian John on 30/08/2015 12:59:31

Edited By Brian John on 30/08/2015 13:00:18

[pgk pgkParticipant @pgkpgk17461]

You can cheat with screw cutting on the lathe ..in the sense of cutting a partial thread then running a die down to clean up and complete it to depth – the lazy way to avoid calculation and thread wires. saves a lot of die effort on a long thread.

[Peter HallParticipant @peterhall61789]

You can lock up the carriage tight if you are only using the cross-slide or topslide to move your tool. It removes one possible source of play. I have unimat and toyo lathes with the same sort of lathe bed. In my experience you'll never entirely eliminate all the play in the carriage. There will probably be some adjustment underneath the carriage. To access that, you'll have to turn the machine upside down. Oh. And if that's a drip tray underneath, you'll have to remove that too. If this hobby doesn't keep you fully occupied for the forseeable future,I'm a Dutchman

 

Pete

Edited By Peter Hall on 30/08/2015 13:18:12

[AjohnwParticipant @ajohnw51620]

Finish – I would be wondering if your tools aren't sharp any more. Turning at too high a speed, maybe running the lathe backwards and also harder materials can do that pretty quickly. Aluminium cutting speeds are usually stated as being pretty high but tools will last longer if it's cut at much lower speeds. Aluminium oxide is pretty abrasive stuff and it oxidises in air very rapidly. Free cutting stainless isn't to bad to machine. Real stainless is a bit of a pig.

It sounds like the locking screw also forms part of the gib adjustment set up. However it looks like a saddle lock so that is a bit unusual. The cutting pressures should keep the saddle firmly on the V on the bed. This is why some lathe info states the bed width but no one mentions what an ideal width is. Some lathes have a gib that runs under the rear bed strip and that holds it down as well and prevents it from being rocked by hand but strictly speaking it shouldn't be needed with this design of bed.

I did mention adjusting the screws with locking nuts on them on each of the slides earlier. It's not a 5min job and usually needs several tries to get it right as things settle down. You will need to oil the slides really.

I'm not suggesting you should but if you had bought a Peatol from the UK you would have found the instructions for doing this interesting bearing in mind that they are machined to a very high standard. They suggest taking the lead screws out and mixing some kitchen cream (CIF etc mildly abrasive) with oil and applying this to the slides and sliding them back and forth by hand and adjusting the gib screws until a smooth even pressure is obtained. This is sort of super machining them. Then clean up and oil and adjust the gibs so that some friction can be detected when they are slid by hand. This needs to be even too so all of the screw need setting and locking.. Then refit the lead screws.

It's possible to set the gib screws by moving the slides via the hand wheels but they offer a lot of mechanical advantage so it's important to stress adjust for SLIGHT even resistance through out their movement range. What I usually do when I get a lathe is tighten them all firmly. Hopefully that gets everything in the right place. Then one at a time I loosen them and retighten so that the screw are just touching the internal gib strips. They then only need very tiny tweaks but that might involve tightening or loosening some of them. As each screw is adjusted the slide can be moved to see what is happening. Tightening the lock nuts sometimes messes this up on some or all of them. which is one of the reason it may have to be done again.

To be honest not taking the lead screws out and doing it by hand is being lazy. I'm as guilty as others in that respect. The by hand way can show if the slides are factionally too tight and causing the oil film to break down. Some don't bother at all and like them very loose. That's ok if cuts are large enough and the feed even enough to keep everything firmly pushed in place. On some lathes loose slides are a complete and utter no no what ever some one does. They vary. The bits and pieces on rather large lathes are so heavy that they don't move around anyway when light for them cuts are taken.

If only all lathes had tapered gibs. They are so easy to adjust but very costly to add. My boxford uses recessed grub screws and no lock nuts. Mmmmmmm I thought when I bought it but as the screw fit is good it's easier to set them and they don't drift out of adjustment. A big plus is that things don't change when the lock nuts are tightened as there aren't any.

John

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Edited By John W1 on 30/08/2015 16:06:16

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Brian John on 30/08/2015 12:35:33:

Before I tightened this bolt up a bit there was movement in the carriage. Obviously tightening it up a lot stops it moving but a 1/4 turn removed the slight wobble it had. I was still having problems with getting a clean finish today. I am hoping that when I try tomorrow, things will be better now that I have removed all movement from the carriage.

.

Brian,

May I suggest that you have a good look at 8.4 in the user manual.

There is a very clear 'exploded view' from which you should see how the mechanism works. … The grubscew and the caphead underneath are for adjustment; the caphead on top is specifically for locking [and is typically used when you are taking facing cuts].

MichaelG.

[Brian JohnParticipant @brianjohn93961]

Well, that is a bit awkward isn't it …why on earth put the adjustment screws UNDERNEATH ? Is it like that on all lathes ?

Tomorrow I will remove the tailstock and wind the carriage up to that end. Then I will slide that end of the lathe so that the carriage is hanging over the edge of my workbench and I can access under the carriage. Most of the weight of the lathe is at the headstock end so it should be safe to do it that way.

I just had the idea of putting a dremel diamond cutting wheel in the lathe chuck and using it as a slitting saw. The axle would be held in the tool holder and fed into the saw.  All very fine in theory but the dremel shaft may not be long enough or thick enough for the chuck to grip and the tool post may have problems gripping the round 6mm bar. I could make and 6mm diameter arbor   to take the dremel wheel….still thinking !

Edited By Brian John on 30/08/2015 18:17:14

[Neil WyattModerator @neilwyatt]

> Well, that is a bit awkward isn't it …why on earth put the adjustment screws UNDERNEATH ? Is it like that on all lathes ?

In essence, yes, because the non-adjustable surface should be the one that takes the usual cutting loads.

Neil

[Gas_mantle.Participant @gas_mantle]

Surely the leadscrew bearing at the tailstock end will prevent the carriage moving that far ?

I was able to adjust the carriage lock bolt on my machine from underneath, it's a bit fiddly but shouldn't take more than a few minutes.

As for the Allen bolt idea of locking the carriage on these bench lathes it seems to me there must be a better way, invariably the compound slide is over the bolt head and makes getting the key in a bit of a pain. I thought about grinding down the short side of an Allen key and leaving it in situ.

Peter.

[HopperParticipant @hopper]

Posted by Brian John on 30/08/2015 12:35:33:

Thank you for all the advice.

Hopper : I have taken note of those suppliers and I will call tomorrow. Yes, I may need your help soon ; I live at Mooroobool.

Mooroobool: no worries mate. I'm in that area quite a bit. Check your PM box, I'll send you my phone number so you can give me a call. I'm retired so you can catch me at home just about any time.

Re the aluminium rod, if you want that to make a mandrel, I would use some Bright Mild Steel bar from Tonkins. It machines very nicely and will be more sturdy for a mandrel than ally. At the 6mm diameter size it costs only a few dollars a metre so you might as well get some stock in. Avoid the black mill-scaled hot-rolled steel bar if you can. It does not machine as nicely as the cold-rolled "BMS".

I have a beginner's lathe book by Harold Hall I could lend you too. It starts from the very basics and works through a series of exercises and might be of some help.

[Brian JohnParticipant @brianjohn93961]

Well, good news and bad news ! I removed the lathe from the workbench to look underneath the carriage. There were two cap heads there but neither one was keen on moving in either direction so I decided to leave leave them alone rather than create more problems.

Now that the lathe had been lifted off the bench I decided to drill two holes through the timber bench top to bolt the lathe down. There are two holes already drilled in the drip tray so I could use these as markers. Problems arose when trying to push the bolt through from underneath. After much trial and error and moving the lathe about I eventually discovered that the holes in the base of the lathe are threaded 1/4 inch which is strange considering that it is a metric lathe designed in Germany.

Having successfully bolted the lathe to the workbench using 1/4 X 3 inch hex bolts and removed all the play on the carriage it was time to have another go at the mandrel. The lathe is as dead as a doornail ! I have tried everything but it will not work at all. I am now waiting for the technician to call me and offer advice.

I did buy 1 kg of aluminium bar stock from Norweld today : 6mm, 10mm and 15mm. All for only $10 so that should keep me busy when I get the lathe going again.

Edited By Brian John on 31/08/2015 06:55:32

Edited By Brian John on 31/08/2015 06:56:42

[JasonBModerator @jasonb]

By the looks of things the 4 grub screws are used to adjust the gap between carrage and bottom plate and then the two capheads tightened up. So to adjust (reduce play) you need to loosen the capheads, slightly loosen grub screws and then retighten the cap heads.

You really want to use a larger dia material than the bore for the mandrel, as Neil said somewhere earlier the flywheel wants to tighten against a shoulder.

Check that none of the micro switches are open.

J

[Brian JohnParticipant @brianjohn93961]

Yes, I strongly suggest the micro switches. The company also second that idea. They are going to send me some photos by email of what I have to open up and how to adjust them. I have already had a look a tried a few things but nothing is working. Of course it may not be the micro switches at all.

Regards the mandrel : if I make the expanding mandrel then could I not use a 6mm nut and a large washer as a shoulder for the flywheel to tighten against ie. it will have a nut and washer on both sides ?

Edited By Brian John on 31/08/2015 08:24:44

[MalcBParticipant @malcb52554]

 

 

 

"After much trial and error and moving the lathe about I eventually discovered that the holes in the base of the lathe are threaded 1/4 inch which is strange considering that it is a metric lathe designed in Germany."

Nothing strange in that Brian if it's actually manufactured in or around China. They have a nasty habit of mixing imperial with metric fasteners in their manufacture and build.

 

 

Edited By Malc Broadbent on 31/08/2015 08:53:36

[JasonBModerator @jasonb]

Posted by Brian John on 31/08/2015 08:08:53:

Regards the mandrel : if I make the expanding mandrel then could I not use a 6mm nut and a large washer as a shoulder for the flywheel to tighten against ie. it will have a nut and washer on both sides ?

Edited By Brian John on 31/08/2015 08:24:44

If you are having a nut both sides then that means you will be placing the flywheel bore against a threaded shaft, you will not get the fit or concentricity required. The flywheel needs to be a very good slop free fit on a plain parallel shaft for at least 2/3rds of teh hub width.

[JasonBModerator @jasonb]

Make your mandrels something like these. expanding at the back, nutted at the front. in both cases the hub should come most of the way over the split or thread

[Howard LewisParticipant @howardlewis46836]

As has already been said, you don't have to have an Aluminium mandrel for an Aluminium component. In fact it would be better not do that. If the Al flywheel should slip on an Al mandrel, there could be local welding, and then in worst case, the two could be welded together, and only separable with force. Even if the worst case did not happen, there could still be scoring damage in the bore of the flywheel.

Mild steel should be easy to turn, FAR easier than stainless. Just don't try taking deep cuts.

Ensure that the tools are sharp, and set at centre height, and don't try to take deep cuts, "Slowly, slowly, catchee monkey".

Cut up tins, or coke cans for shims to adjust the tool height. Faced with a choice of a thou or two above or below centre height, go below. This will give increased front clearance , whereas above the tool will not cut properly, and merely rub.

High Speed Steel tools will cope better with small cuts than disposable tip Tungsten carbide tips.

(But this then gets you into grinding tools, which you will need to learn, eventually)

The advice on parting off is all good. Lubrication can help. For Al, kerosene is a good lubricant. Occasionally withdraw the tool to clear swarf, and when cutting, keep a small but steady forward feed. Don't let the tool rub. Don't force it, that will be likely cause dig ins, possibly a broken tool, even a scrap workpiece.

If there is a build up on the edge of any tool, stop and remove it. Lubrication helps to prevent this.

If you suffer chatter with any tool, reduced speed often helps, as will lubrication, sometimes.

If you decide to make split mandrels, remember that the central screw(s) will need to have the head turned to a taper so that the mandrel is expanded as the screw is tightened. Ten degrees (Five degrees Topslide offset) should be enough. My advice F WI W is to use as large a diameter screw , as possible, within reason.

You'd be pretty sick to have a M3 shear off, when a M4 or M5 wouldn't have!

Since you are bolting down the lathe, the bed needs to be free from twist. If the bed is twisted, it will not be possible to turn parallel over any length. (It won't turn parallel over a short length, but the error over a short distance will barely be detectable). If bolting to a wooden bench, my advice would be to have a piece of 3mm steel under the chip tray, to spread the load, before starting to remove any twist.

Since you are cutting dry, the level from Headstock to Tailstock does not really matter, but it is important that the front to back level is the same at both ends.

If you can get hold of a copy of the Myford Series 7 Manual it sets out how to remove twist from the lathe bed.(see page 42; although the same info will be available elsewhere, for sure). Turning a holding down nut just a flat can make a difference!

Do take up offers of help, you will learn, by seeing as well as hearing of how others do it.

Good luck! You'll get there in the end, but try to learn and make your mistakes on material. that you are prepared to scrap, not raw castings for you next project!

An undersize bar originally meant to be 6mm can always be raw material for a 5mm or 4mm piece.

(But I am an inveterate hoarder. "It'll come in useful one day&quot

Experience is what allows you to recognise the mistake, the next time that you make it.

Keep trying.

Howard

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Howard Lewis on 31/08/2015 11:09:58:

Since you are bolting down the lathe, the bed needs to be free from twist. If the bed is twisted, it will not be possible to turn parallel over any length. (It won't turn parallel over a short length, but the error over a short distance will barely be detectable). If bolting to a wooden bench, my advice would be to have a piece of 3mm steel under the chip tray, to spread the load, before starting to remove any twist.

.

Howard,

It's interesting to compare your advice with that in the manufacturer's user manual [which I linked a couple of pages back]. …. Bear in mind that the lathe is apparently designed to be gentlly fixed using two 1/4" bolts.

MichaelG.

[Brian JohnParticipant @brianjohn93961]

''gently fixed'' ……why would that be the case ?

The lathe is not working at all at this point. I am hoping that the company can come up with a solution tomorrow otherwise it will have to go back.

I might open up the casing up tonight and look at the micro switch arrangements or see if I can see anything else that does not look right.

 

 

Edited By Brian John on 31/08/2015 12:10:30

[Frances IoMParticipant @francesiom58905]

almost certainly in your moving of lathe you have dislodged either a power feed (check especially connections from plug to machine as if lead caught + pulled one connection may be broken or pulled out of a screw terminal block) or a internal connection dislodged – are no pilot lights on ? – there is usually a fuse buried somewhere on motor controller has this become dislodged ?

A somewhat more worrying possibility is that a small bit of swarf has entered motor controller box and shorted something but normally such usually result in a loud bang + smoke

Edited By Frances IoM on 31/08/2015 12:32:22

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Brian John on 31/08/2015 12:07:42:

''gently fixed'' ……why would that be the case ?

.

 

3.3.2 Assembling

ATTENTION!

The lathe can slip slowly during operation on the ground. Attach the machine to the ground.  Attach the lathe to the provided through holes (2 pieces) along with the chip pan and the intended base.

 "Dimensions, installation plan“ on page 18

ATTENTION!

Tighten the setscrews on the lathe only until it is firmly secured and can neither move during operation nor be turned over. If the fixing screws are too tight in particular in connection with an uneven substructure it may result in a broken stand of the machine bed.

_______________

.

Edit: …. I can understand that readers of this thread may not have read the manual, Brian … But I think it would be very wise for you to do so.

Edited By Michael Gilligan on 31/08/2015 13:10:08

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