Index Parting tool

[Bernd]

Nice vid there websterz.

I use a rear post on my Sherline and Grizzly 9 X 19. Both work nice just like you showed. The one on my Logan lathe has to be front mounted and cut the conventional way. There's no way of mounting a rear tool post. If I set it up correctly it'll cut very nicely with automatic feed.

Again, nice vid and explation.

Bernd

[Bluechip]

Darren

You should be OK. This is the one I have:

http://www.iscar.com/ProductLines/ProductLineSubDetail.asp/CountryID/1/ProductLineSubDetailID/717

or very near.

Got it with the S7. plus 40 or so tips.

Sh*t Hot. Have to get it absolutely square to axis on deep cuts tho. But then we should do that anyway. 

Shouldn't I...  Yes, you should Dave ..

Dave BC

[Darren]

Yes you should Dave.....

The one I have just bought will only do shallow cuts, how much I have no idea, but will prob part a 20mm bar ok.

I will still need to find another to take deeper cuts.

But as they say....you can't have too many tools......

[Bluechip]

Darren

It's the slurp. Beer and lathes don't mix. But I'm working on it.  Practice, practice, practice.

I think it's the groove on the top face of the insert. This seems to 'fold' the swarf in on itself. It don't make a tight curl like my other parting tools.
Bogs is spot on, give a good feed. I've noticed it works a lot better that way.

I'm off. Sausage butty time ..

Dave BC

[John Hill]

Bluechip, that looks just like mine though mine is SECO brand.  It sure does cut and does not mind being well fed,  but 'crikey' (as the Aussies say) if you make a mistake and the blade breaks it does not half cause a laundry emergency closely followed by a significant wallet droop.

[Bluechip]

John

There's a fair number of makes along similar lines. I didn't get a laundry emergency, I run the Myford on a fairly fast speed usually to part off.

If I get a dig-in, the belts slip. But then I use the lathe mostly to part off ally & brass, if it's steel, I use a Sabre saw. Not too keen on trying to part off 2"+ alloy steel. On the few occasions I need to, I part off part way between centres, low speed, the saw the rest. Not recomended I know, but if I leave about 3/4"dia. to saw the practice seems harmless. So far ..

Dave BC

[John Hill]

So far Dave I have only worked steel, a little cast iron and a few bits of unknown aluminium alloy.

The first breakage was because I moved the lever to select long instead of cross feed and the second was cutting 22mm mild,  I dont know what I did wrong but I usually take it in and out a bit to widen the cut and maybe I did not do that enough or I did it too much and allowed chips to get down beside the blade,  either way it went with a terrific bang and snapped those teeth (that hold the insert) off the end of the blade.

[No1_sonuk]

I dont know what I did wrong

I do.  You didn't lock the carriage! 

[NickG]

I have no carriage lock on mine and don't lock the carriage for facing or parting ... is it something I should be doing?

How do people get the parting tool exactly square? I leave the tool post unclamped and with a silly angle then bring the carriage up so the tool touches the face of the chuck jaw and keep going until it looks parallel.

I've often thought it's a good idea to go in and out to widen it a bit to avoid rubbing, but now I try to get it as straight as possible and just go through it. I usually use about 200rpm (slowest none back gear) and for brass and aluminium, I seem to be able to use the slowest power feed which is good as it's nice and consistent. Can't do that on steel though, nearly broke the tool. My motor is powerful and the head is geared too so it'll break tools before any belts slip!

Nick

ps, why do rear tool posts with the parting tool other way up work better? Is it because it cant try to drag tool under?

[No1_sonuk]

I have no carriage lock on mine and don't lock the carriage for facing or parting ... is it something I should be doing?

It does help.  What machine do you have?  It might have one you don't know about - Someone recently asked on the Chester forums about modding his DB7 to add a lock.  I pointed out to him it already has one, but it's not documented.

If you really haven't got a lock, some people disengage the long feed leadscrew from the spindle, and engage the half nuts to lock the carriage in place.

How do people get the parting tool exactly square? I leave the tool post unclamped and with a silly angle then bring the carriage up so the tool touches the face of the chuck jaw and keep going until it looks parallel.

I use the face of the chuck, but yes.

ps, why do rear tool posts with the parting tool other way up work better? Is it because it cant try to drag tool under?

Yes.

[bogstandard]

Nick,

For parting AND facing (don't get the first letters muxed ip), the most important part is to get the saddle locked, plus the topslide (compound) if you are parting.

Without it being rigid you will be getting tapered cuts and putting side strain on the tooling. At one time, it was thought that having an angled face on the front of the parting tool would help enormously. But people were finding that it was snapping the blade off because it was putting a side load on the tip. The cutting face must be square to the blade and the blade has to be square to the job. I don't suffer from any of those problems because my toolpost is invariably always spot on square. Just drop the holder on, and the tip is square to the job.

The reason why rear parting SEEMS to work better is a bit of a conundrum. All sorts of theories have been come up with, but all can be disproved one way or another. My personal view is that the chips fall away rather than get jammed on the tip. But again, that is just a personal view.
I have never had to do it because I don't have any trouble parting at all, and never have had, even with smaller less rigid machines, just a little more care has to be taken the lighter you go with machinery or the smaller the parting tool. I regularly part off brass up to 1/2" diameter using a 0.025" (0.6mm) wide parallel tool.

Your heavy machine should be able to part off under power at a high speed on non ferrous, and a fairly fast hand feed with nasty ferrous materials.

A square, very sharp tool, on centre or a couple of thou above to allow for tool flex, lubrication and cooling, and a steady CONTINUOUS feed is always the way I tackle parting. Depending if it is a fast or slow feed, and of course material, I sometimes omit the lube and coolant. Brass, bronze, cast iron and some of the leaded steels, I don't bother. For ali and stainless, then definitely used.

John

[raynerd]

If you really haven't got a lock, some people disengage the long feed leadscrew from the spindle, and engage the half nuts to lock the carriage in place.

I regularly do this on my Boxford as there doesn`t seem to be any other inbuilt way of locking the carriage. I do it when parting because I read it somewhere  and didn`t have a clue until I read this thread about side strain on the tool. When facing, I have to do it or the carriage runs away towards the tail stock as I put pressure on the face of the work - it pushes the carriage.

This thread has inspired me to purchase the indexable one from RDG so I`ll let you know how it goes - it was a little pricy at £28 so it better do a good job.

Chris

[Darren]

Do I see a video coming Chris......

Please.....

[raynerd]

haha - sure mate. I`ll try and get one done tonight - hopefully could be a video of it parting my new pulley for this boxford - 2 1/2 inch alley. It will probably be normally front mounted as I don`t have T-slots on my cross slide. I do want to eventually rear mount it but on the boxford it will mean machining and modifying the cross slide.

It was mentioned before that parting from the front upside down and in reverse would in effect be the same from running it forward and parting upside down from the rear. Of course, this seems logical but I have been told from words of wisdom that from the rear works better - he doesn`t know why but it does. Is this just his experience or has anyone else found the same?

Chris

[No1_sonuk]

It's essentially the same, so it shouldn't be different.  However, rear-mounted would usually be in a fixed, dedicated tool post, that once set up can be left as-is.  The front/reverse/invert method would need some setting up every time.

Another issue is the chuck fixing.  If your chuck is threaded on, I would assume it might undo if you use the reverse option.

[NickG]

Thanks John, I've never thought of using lube and coolant parting ... silly me! I really could do with sorting the suds pump. I am the same, power feed for aluminium and brass seems to work but even the slowest speed seems a bit fast for steel.

No1_sonuk, my lathe is a harrison L5, don't think it has any dedicated method of locking, but I could engage the half nuts as mine has a separate shaft with a dog clutch for threading. With my other lathes I've had to lock it but maybe because this one is so heavy, I just leave it and it seems to stay put whilst facing / parting. Maybe I'd get even better results if I did lock it though. Can't remember how it's adjusted, may be able to turn grub screw on a gib into a lock.

Interesting anyway.

Nick

[Darren]

Nick, what do you think of the Harrison ?

It seems a common enough lathe that one may pop up at the right price....

[John Hill]

OK then, carriage must be locked? Obviously then the practice I saw recommended of widening the cut is not the go?

I am always careful to square the blade with respect to the ways by sighting the edge of the blade against the machined face where the travel steady mounts,  maybe I am a bit timid on the RPM as I usually use 340 unless I can see a good reason to go up or down.

Plan of action:

1. pour double scotch.
2. chuck up some 22mm mild.
2a. put chuck key in its proper place
3. square the blade.
3a position blade at cut off point
3b. lock saddle
3c. lock compound
4. select 340RPM
5. select a slow(ish) power feed
6. erect plastic splash shields
7. start coolant pump
8. direct coolant at tip of blade
8a. don safety goggles
8b. close chuck safety
9. start spindle
10. engage power feed
11. wait and watch
12 when blade breaks chuck back scotch to steady nerves, switch off and go upstairs.

Alternative:
Put workpiece in cold saw vice.
Douse blade with cutting fluid.
Start saw.
Lean on saw handle while thinking of red-head next door.
Switch off saw.
Release vice.
Carry workpiece to lathe and carry on.

[NickG]

Darren,

I can't really fault the harrison at all, it was probably one of my best decisions ever! It is very heavy and takes up quite a lot of room, but I guess that is partly what makes it so good. Mine is an L5, 4 1/2" centre height, 24" between centres I think, (think it's actually  4 5/8" but they call it a 9" swing.) with a screwed spindle. It has power cross feed, quick change gearbox etc. Mine has 8 speeds from 34 rpm to 720, have hardly ever used the top speed though. They are all selectable via levers on top of headstock. Some of the later ones were 11" swing and had camlock chucks with bigger spindle bore, they also had 16 speeds, you could double everything up but this was via motor speed so you would need to retain 3 phase. Some of them had gap beds, mine doesn't, not too bothered though, makes it even more rigid. Oh, it also has a light and suds pump built in. Very solid machine, superb quality. I got mine for £650 with accessories, although the 3 jaw had had it, then I spent about £100 on motor. About £750 seems the going rate. A lot of them come from schools where they have had little use, some have been abused, some have hardly been touched. I remember at our old school, the boxford got all the hammer .. was still a great machine. There was a harrison too, but only ever saw somebody turning wood on it! There do seem to be quite a lot about, if I was being ultra picky, about the only thing I can think of that it doesn't have is a T slotted cross slide. That could be handy for boring between centres etc. The 11" with large spindle bore would also be better I guess, could make some pretty big stuff on that. A DRO system would also transform it!

When I was looking to change mine I was looking at all sorts from chinese ones to 2nd hand smart and brown, I actually bid on a couple of those but it wasn't to be. That's what you have as well as your mini lathe isn't it?

John     I would select the slowest power feed! I know exactly what you mean though, I sawed things off today rather than setting up my parting tool, it was just faster and less unnerving!

  at red-head next door ... nice is she?!

Nick

[websterz]

You forgot "Share candid pix of red-head next door with good people at Madmodder"...

[Darren]

Mine has 8 speeds from 34 rpm to 720, have hardly ever used the top speed though.

When I was looking to change mine I was looking at all sorts from chinese ones to 2nd hand smart and brown, I actually bid on a couple of those but it wasn't to be. That's what you have as well as your mini lathe isn't it?

Crickey, I hardly ever use anything lower than 750rpm, usually 2 or even 3,000 rpm....except when I decide to partake in the joy of parting off....!!

A friend of mine has the same lathe as yours and loves it, but then it's the only one he has ever used. Has made some nice stuff on it though.

You're right have a S&B model L, a 5C collet nose with a thread for chucks as an afterthought.  I love it, strong as an Ox, but I wouldn't recommend it as an only lathe due to no leadscrew. Anyone reading beware, Model L's with 5C collets are rare beasts, usually have S&B's own collet facilities which they are getting much harder to find.

I do rather fancy one of the other S&B's as they all have collet noses I believe ( and I have a set of collets to fit). There are a couple local but not for sale.

[NickG]

I must admit I was slightly put off when I first got it by the low speeds and tried to fit a two pole motor which would double up all the speeds, but they just didn't have the torque ... even if it was a bigger motor. So I got the 4 pole one, back down to original speed and it's amazing, I just don't need the high speed. I could turn 1/8" steel at about 350rpm and still get a really good finish. Most of the time it's just left at 465 rpm or what ever it is, 1 below top ...I forget the actual speeds.

They are a gorgeous piece of kit, I'm sure the one I was looking at had all the feeds etc.

I also looked at another thing called http://www.lathes.co.uk/hembrug/ . It was a tool room lathe made for dutch ordnance factory though ... what a piece of quality. There were some bits missing though and thought sort of making them, they'd be like rocking horse s**t to find!

So I am a big believer in quality old machines, I just couldn't find a nice old vertical mill for the price I was looking for. Tom Seniors etc are all well known and fetch too much money.

Nick

[Darren]

I only use high rpms cos there are no machine feeds, hence my love of carbide tooling. But it works and the finish is excellent.

Nothing wrong with slow speeds, after all it's an industry standard machine. The feeds make it all work......

I am looking for another lathe, a Herbert with a mass of tooling was offered to me for £200, but it's just not what I'm looking for in a machine.
I will find one eventually.....hopefully an S&B if I'm lucky.

If you really want another mill and can house it forget the popular stuff, Toms and Harrisons, too expensive for what they are. You can get something sturdier for a fraction of the price.

Take my Beaver, 20mm cutter, 800rpm and it'll plough through an inch of steel with no complaints. Still a real eye opener every time I use it. I'm looking for a lathe like that.

I was offered a Colchester master recently with a VFD fore silly money, but it was too far gone. And it was too big, as much as I like big lumps of iron.

[NickG]

Masters are big! Something like a chipmaster has good capacity but is relatively compact ... still weigh a ton mind you! Used those and students at uni and they were both superb machines.

Yeah, I'd love something like the mill you have. I always used to think small, but with good quality large machines you really can do everything on them. Having said that, the way my workshop / garage is now is just about right because i can still get a car in the middle ... not that I do at the moment but it could come in handy!

[Darren]

My index parting tool arrived today. At 25mm sq the shank sure is sturdy.
A little on the large side but my thinking is to fix it directly to the top slide and not a tool holder. I gave it a go but had to wedge it to get the tip on centre.
I realise the angles are now way out, but it cut through this non-free cutting steel like butter....



The surprising thing is it didn't like the very low speeds I'm used to parting with. Whacked it up to higher speeds and it just ploughed through with no fuss at all. No need to be gentle it seems.



Now to think about how I'm going to mount it. Maybe let it have a little chat with the miller to correct the centre height, drill a vertical hole in the middle and use a T-bolt to clamp it directly to the slide......unless someone has a better idea?

It'll cut to a depth of 15mm, so will deal with a 30mm bar. Even with a 50mm bar it would only leave 20mm in the centre to hacksaw. But then most things we make have a hole down the middle anyway....