New lathe arrived today : The ongoing saga

[Brian JohnParticipant @brianjohn93961]

The lathe has been repaired ; the technician bypassed both reed switches and the lathe is now fine. We took the chuck guard off completely but I put it back on later. I can swing it out of the way to the open position and the lathe will still operate so that is the main thing. I may take it off later.

Back to the mandrel : a 5mm allen key tool arrived this morning so that has made life much easier instead of using the regular allen key which was supplied. I also tried out the carbide cutting tools, one of which you can see in the photo. I am not real impressed but maybe they need a few swipes with a diamond file to get them working well. The HSS tool is giving me a much better finish at 800 RPM.

I am using aluminium bar this time as it is easier to work. The bar is 16mm and the part which goes through the flywheel has to be reduced down to 6mm ; so far I am down to 12 mm. I started taking 0.1mm cuts and then increased this to 0.2mm cuts. I am also using the new live centre….. just because I have it. I do not notice any difference between the live and the dead centre at this stage.

I am using the ball bearing oil point on the front of the chuck as my reference to the workpiece which has been marked with a black marker. I hope to finish this down to 6mm tomorrow then drill and tap for an M4 socket cap. I am still not sure how I will cut the slits yet.

 

Edited By Brian John on 03/09/2015 07:09:56

[Martin KyteParticipant @martinkyte99762]

Hi Brian

It's difficult to see from your photograph but I would say that the carbide tipped tool is being used on it's side. Looks like a left hand knife tool to me. Should be installed with the screw on the top face. If it is a left hand tool you cannot use it for facing or cutting from the right hand end of the work which is possibly why you installed it as you have.

Martin

[HopperParticipant @hopper]

Ah, that's progress now! Great to see you got the reed switch problem sorted for once and all! Generally speaking, a good sharp HSS tool will give a better finish on ally than a standard carbide tool. They do make indexable (replaceable) tip carbide tools with a specially ground sharp finish for machining ally and brass etc. But your standard brazed tip carbide tool is best for steel. Just make sure the tip of your tool is at centre height and carry on turning. 800 rpm is about right for ally that size. You could go a little faster but better to go slow and steady than too fast.

[AjohnwParticipant @ajohnw51620]

Posted by bodge on 02/09/2015 13:56:32:

Tallow . bovine as in cattle , nearest substitute probable dripping.

bodge

A quote from the wiki

Tallow is a rendered form of beef or mutton fat, processed from suet. It is solid at room temperature. Unlike suet, tallow can be stored for extended periods without the need for refrigeration to prevent decomposition, provided it is kept in an airtight container to prevent oxidation.

In industry, tallow is not strictly defined as beef or mutton fat. In this context, tallow is animal fat that conforms to certain technical criteria, including its melting point. It is common for commercial tallow to contain fat derived from other animals, such as lard from pigs, or even from plant sources.

There is no way of knowing exactly what was in it other than it was different to what is commonly available now.

John

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[JasonBModerator @jasonb]

Martin, first photo is the HSS tool which has a groove in the edge, second photo shows the brazed tip carbide tool laying infront of the lathe

Brian, with the metal held vertically in your bench vice just use your junior hacksaw to cut the slot, no need for being soper accutrate with a slitting saw. Just best you can do straight down the middle. Remember to only use the taper tap so the screw will act like a wedge against the tapered thread.

J

[Martin KyteParticipant @martinkyte99762]

That would explain it Jason.

Martin

[Neil WyattModerator @neilwyatt]

Tallow

I wonder if there is any mileage in Atora vegetarian suet

Neil

[Brian JohnParticipant @brianjohn93961]

Okay , taper tap it will be. I think I will buy a new hack saw before I make the slits. A better quality saw should give a better result. I am only using a $5 baby hack saw which I have had for years !

It would be nice to work out a way to use the rotary tool with the carborundum cutting wheel but I do not think it would hold a straight line very well.

Are 0.2mm cuts adequate …it seems to be taking a long time to reduce it to 6mm ? I know most people probably have much larger lathes but what sort of cut could I reasonably expect to make with a lathe this size  working on aluminium ?

Edited By Brian John on 03/09/2015 11:51:38

[Neil WyattModerator @neilwyatt]

I would not be surprised if you can take 1mm cuts in aluminium with a sharp tool with plenty of top rake.

<edit> the manual suggest an 'ap' of 0.4mm for outside machining of medium carbon steel, I assume ap is depth of cut </edit>

In time you will develop the ability to recognise when the lathe is struggling and when it can take a deeper cut.

Don't expect good results with brazed carbide tips on small lathes, keep on with the HSS or invest in one of the indexed screw-attached cutters as recommended for beginners in the manual..

Neil

Edited By Neil Wyatt on 03/09/2015 12:04:28

[AjohnwParticipant @ajohnw51620]

A full sized hacksaw is likely to leave too wide a slot not that this matters much. A junior hacksaw would be best and the ones that have a tensioning screw are probably preferable.

I would do it in they lathe as you will loose concentricity if you remove it from chuck. You should do it after the final location diameter has been turned for the same reason. So drill, tap, slit and then use.

John

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[John Stevenson 1Participant @johnstevenson1]

Is it just me or do others think that HSS tool has come straight out the packet ?

Can't see anything that looks like rake on it.

[AjohnwParticipant @ajohnw51620]

I think it's one of the minimal grinding ones John. Just grind a shallow "groove" on the cutting edge and maybe leave the front clearance as it comes on most tool bits and add some side rake. Less work than a normal bar turning tool.

Bit like adding a chip breaker.

John

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[Brian JohnParticipant @brianjohn93961]

These HSS tools were purchased from Arceuro.

[Gas_mantle.Participant @gas_mantle]

Posted by John Stevenson on 03/09/2015 13:26:14:

Is it just me or do others think that HSS tool has come straight out the packet ?

Can't see anything that looks like rake on it.

Looks very much like a right hand knife tool to me :-

**LINK**

[roy entwistleParticipant @royentwistle24699]

It looks like a blank unground piece of HSS to me

Roy

[JasonBModerator @jasonb]

As Peter says its the R/H one from Arc, if you can't see the groove then I suggest a trip to specsavers

Edited By JasonB on 03/09/2015 15:01:46

[John Stevenson 1Participant @johnstevenson1]

Right, Specsavers first thing in the am.

Very handy actually as it just across the road from Weatherspoons who do a lovely breakfast for £2.39 and a bottomless cut of coffee thrown in for 99p.

[Neil WyattModerator @neilwyatt]

Posted by John Stevenson on 03/09/2015 21:37:01:

Right, Specsavers first thing in the am.

Very handy actually as it just across the road from Weatherspoons who do a lovely breakfast for £2.39 and a bottomless cut of coffee thrown in for 99p.

You've got bottomless cups of coffee in your workshop – it dissolves straight through the china.

Neil

[Brian JohnParticipant @brianjohn93961]

I had another go at making this mandrel. I reduced the smaller shaft that goes through the flywheel down to 6.1mmm and then decided to part off the larger shaft. I got only so far parting off before the bar started bending so I finished off with a hacksaw. Is this normal procedure ?

I have drilled (2.4mm) out the mandrel to take an M3 socket cap. I do not think an M4 is necessary for aluminium. I would use an M4 for steel.

Problems arose when trying to finish the mandrel so that it would a accept a drilled flywheel with a 6mm hole. What diameter should I be aiming at ? I went for 5.95mm and ended up with 5.85mm ! I do not know how this happened as I was being so careful near the end ; the cutting tool also seemed to dig in as I wound it along. That last 3mm close to the shoulder is down to 5.6mm….useless ! I do not think this mandrel will now work but I will use it to practise tapping the hole and cutting the slits.

I am still not happy with the finish I am getting.

UPDATE : I have just noticed some play in the top slide. I had adjusted this and locked it down the other day. It is obviously something that needs to be checked constantly.

Edited By Brian John on 04/09/2015 07:53:52

[mahgniaParticipant @mahgnia]

Brian,

Please do not part off material between centres…

Andrew

[Gas_mantle.Participant @gas_mantle]

I'm no expert but surely you are making a lot of work for yourself here.

Why not just turn the end of a piece of stock to a diameter that is a very close fit to your flywheel axle hole, cut an external thread on the end then use a nut to secure your wheel. I've done it a few times now and never had any problem using it for small wheels.

Make sure the mandrel shoulder is at least a wide as your wheel hub so that you have a solid true running face to press up against. So long as you don't remove the mandrel from the chuck till the wheel is finished and it's a good close fit you should be able to turn the wheel over to machine the other side.

[JasonBModerator @jasonb]

But if you do part off between ctrs which is quite OK provided you remove the tailstock support towards the end of the cut or as you have done saw it off.

2.4mm is too small for M3 tapping size, as a quick general rule of thumb subtract the pitch fropm the dia. So for M3 x 0.5 you get 3 – 0.5 = 2.5mm tapping drill.

Just because you drilled the flywheel 6.0mm does not mean the hole will be that size, most likely it will be a bit more. Once you start to get nearer to finished size take very small cuts and keep test fitting the flywheel ontop the shaft rather than try to measure an exact size.

Did you have the tailstock centre in place while taking those cuts as a smaller dia nearer the shoulder suggests the work was flexing away from the tool.

[Brian JohnParticipant @brianjohn93961]

Jason : No, I tried to put had the tailstock centre in place but the piece would not rotate without a wobble….I have no idea why so I removed the dead centre and it seemed to be rotating quite well with no wobble. I did something wrong along the way here. I will have another go tomorrow.

Peter : Í did try to cut an external thread the other day but that was on steel with no success. Perhaps I might revisit the idea now that I am using aluminium. Yes, It does seem easier but there are things to be learnt using both methods.

 

Edited By Brian John on 04/09/2015 08:01:17

[Neil WyattModerator @neilwyatt]

> I went for 5.95mm and ended up with 5.85mm !

Don't forget, taking 0.1mm cuts will take 0.2mm off the diameter and so on.

Neil

[John HaineParticipant @johnhaine32865]

Neil, metric lathes are normally calibrated in diameter mode, certainly all 3 I have had are that way.

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