New lathe arrived today : The ongoing saga

[HopperParticipant @hopper]

Brian, what sized holes do want to bore with it, and what material? The larger the boring bar you can use, the more rigid it will be. I think your lathe has a 10mm tool height so should be able to use more than a 6mm boring bar. Most boring bars have a flat ground on the bottom and then the insert is positioned at about half the diameter of the bar.

The bar you are looking at has the disadvantage of the thin and chattery 6mm shank but the large 9mm insert that will not fit in smaller holes to bore them. If you want a 9mm insert, use a 10mm boring bar. If you want to bore 6mm holes, get a 6mm bar with 6mm insert.

I have not had much success with insert boring bars on the old Drummond, but I think if you buy the ground finish inserts made for boring aluminium they will work better on smaller lathes. Make sure the boring bar you get has positive rake for use on smaller lathes. The negative rake ones offer more clearance but require a rigid machine to work well.

Edited By Hopper on 13/11/2015 12:49:20

[AjohnwParticipant @ajohnw51620]

Brians lathe has 7.85mm +0 -0.3mm height form the tool seat to the centre line of the spindle and a 12mm holder.

I would be rather surprised if that wont take a 10mm tipped boring bar. Maybe some one could measure the tip height on one for him. It's best to buy that sort of thing with tips if you can. Often works out cheaper. Eg

**LINK**

And if it's a touch too high it's always possible to file some off the bottom or better still mill some off. The Taig vertical slide can often be fitted to a lathe some how or the other. Neil and me will vouch for it's quality and rigidity. The "vice" that comes with it is even good for various sizes of things. Looks crude but works well.

For the sort of work it sounds like Brian will be doing something more flexible will be needed. I used various sizes of these in the past but generally because I was machining cast iron.

**LINK**

There are also some round solid hss bars about with a bent / forged end. They need grinding as the ends are generally too wide. This is the type

**LINK**

Really though round HSS is just as good. Typically grind the cutting top down to 1/2 the dia and then relief along the side. It's possible to make a holder for these on the lathe. Put a block of whatever usually m/s in the tool holder and drill via one in the chuck.

For max flexibility on hole size HSS tool bits are more or less essential. I'd suggest 1/4" sq bits and maybe some larger sized bits for Brian's lathe. I'll come back with an example shortly.

John

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[Neil WyattModerator @neilwyatt]

Posted by Danny M2Z on 13/11/2015 11:36:26:

G.E.O. Thomas wrote a beaut article on boring bars many years ago in M.E. Maybe somewhere it is archived?

* Danny M *

It's reprinted in the Model Engineers Workshop Manual

Neil

[KWILParticipant @kwil]

Gordon T,

The reason for the difference between website and E*** pricing is to allow for the commission payable to E*** on each sale.

[AjohnwParticipant @ajohnw51620]

This one was made for 1/4 sq hss. Not much needs grinding off the tool bit. Just radius the corner with a little off the cutting side width.

Just ate a lovely bacon sandwich and it finished cooking as I was posting before.

John

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[egaParticipant @ega]

Posted by Neil Wyatt on 13/11/2015 14:00:12:

Posted by Danny M2Z on 13/11/2015 11:36:26:

G.E.O. Thomas wrote a beaut article on boring bars many years ago in M.E. Maybe somewhere it is archived?

* Danny M *

It's reprinted in the Model Engineers Workshop Manual

Neil

Indeed, and I recall urging the OP to invest in a copy some time ago.

[Brian JohnParticipant @brianjohn93961]

I need to drill/bore holes 10mm and 14mm in brass. I think I will go ahead and buy that 6mm indexable tip boring bar. I assume from the flats on the tool that it can be held directly in the tool post…..only the round tools need a holder ? I realise that packing will be needed to raise the cutting tip to the correct height.

I do NOT want to make my own tool at this stage. This will be my first attempt at boring and I do not want to be blaming a faulty tool if something does not work out ie. there will be only one variable…me !

[JasonBModerator @jasonb]

Brian, whats the largest drill your tailstock can hold? you will need to be able to drill 9mm before the tool will fit without rubbing the back/bottom

If you do go for thattool then get a TCMT insert for use on brass and alumininm, as your machine is not teh nost rigid the "blunter" standard tip will have a tendancy to be pushed away from teh work giving a tapered bore. The tool maynot be faulty but it may NOT BE SUITABLE.

There are some nice small HSS boring bars available have a look at some of those.

[Brian JohnParticipant @brianjohn93961]

The drill chuck is a 1-13mm chuck. The largest drill bit I have at the moment is 9mm.

There is a HSS boring bar in the Arc Euro HSS set I bought. I thought the indexable tip tool would be more useful.

[Ian S CParticipant @iansc]

I would suggest that a HSS steel boring bar would actually cause less trouble Brian , but I don't suppose you have anything like a broken tap, or centre drill. One way to make one is to grind one from a bit of 1/4" sq bit of HSS, must take a photo of my one, it will bore from about 3/16".

Ian S C

[mechman48Participant @mechman48]

Try & make your own, re Ian S C suggestions. I have made a few of my own over the years from broken HSS taps…

… a couple of home made boring bars

George.

[HopperParticipant @hopper]

Posted by Brian John on 14/11/2015 08:27:45:

The drill chuck is a 1-13mm chuck. The largest drill bit I have at the moment is 9mm.

There is a HSS boring bar in the Arc Euro HSS set I bought. I thought the indexable tip tool would be more useful.

Get your HSS boring tool out and give it a go on some scrap ally. You might be surprised.

[JasonBModerator @jasonb]

And if it does work then also use your part with the 14mm hole as a practice piece. Bore a 10mm hole and see how accurate and well finished you can get it. Then open the hole out to 12mm again aiming for size and finish and finally do the 14mm finished hole.

This will give you some practice before comitting to a part and you will not have wasted any material as practice pieces

[Ian S CParticipant @iansc]

I'v bought 3 boring bars over the twenty odd years I had my lathe. The first two were about a week after the lathe was up and running, they were a 3/16", and a 1/4" by Eclipse from the shop in Christchurch that was the Myford agent in the area. They were bits of (unpolished) HSS about 4" long, shaped like a hockey stick, about as good as useless. The other one was a good solid one with a brazed on carbide tip, it was great on the job it was bought for, boring 30 mm flame cut holes in 8 mm hot rolled steel discs out to 35 mm, HSS and my home made carbide tool just bounced off the hard gas cut area, then one day as I backed out, Bang and the tip split in half, so we're back to homemade.

Ian S C

[Brian JohnParticipant @brianjohn93961]

Can I use this parallel shank slitting saw held in the lathe chuck ? The work piece (5mm square section brass) will be held in the tool holder.

**LINK**

The saw :

**LINK**

Should I drill a centre hole in the end of the slitting saw so I can support it between centres ?

[egaParticipant @ega]

Ian S C:

GHT made a similar comment about a forged tool which he likened to Harry Lauder's walking stick!

In defence of Eclipse, however, didn't those "unpolished" boring bars have a ground flat on the underside and ground cutting edges? I feel they would have been of some use in the *right* hole; three boring bars seems much too few for the average worker.

That said, I'm all in favour of shop-made tools.

[JasonBModerator @jasonb]

Yes you can use a holder like that in the lathe chuck. Just watch teh sizes, the saw is listed as 5/8 but the holder 5/8-16mm if it is 16mm then the blade won't fit.

Run at your slowest speed

[Brian JohnParticipant @brianjohn93961]

Yes, most of the saw blades are listed in metric but the holders all seem to be imperial. I suppose a 3/4 19mm ID saw would be the way to go.

[Brian JohnParticipant @brianjohn93961]

Here : parallel shank arbor and three saws all in one package from Chronos. This way, I know everything will fit.

**LINK**

[AjohnwParticipant @ajohnw51620]

Arceuro do slitting saws and morse taper arbours that will take them Brian. You may need to make a draw bar for the arbour. I usually use a length allthread to save the bother.

John

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[Ketan SwaliParticipant @ketanswali79440]

Hi John,

I have just checked. Unfortunately, there isn't anything in ARCs current range which will fit Brians needs in respect of slitting saws and arbors for his lathe. All I would say to Brian is, what ever you choose, please be careful when using these products.

Ketan at ARC.

[Ketan SwaliParticipant @ketanswali79440]

Brian,

Did you try using the 8mm HSS boring tool and did it work, or was it a little too high for your tool post?

Ketan at ARC.

[Ian S CParticipant @iansc]

The only finishing on the Eclipse boring bars was the grinding of the cutting edge of the tool, I fitted the end of the round shank into a mild steel block to hold in the tool post, they might have been fairly useless, but I still used them until, with resharpening the hooked end disappeared, I'v still got and use the 1/4" one, the end looks like a D bit, and now that it is shorter it doesn't chatter so much.
Ian S C

[egaParticipant @ega]

Ian S C:

As you describe them they do sound a bit agricultural!

Good to know you got some value out of them.

[Brian JohnParticipant @brianjohn93961]

Ketan

1. Why ''be careful'' ? Are you referring to the danger of using spinning blades in the lathe or the possibility of buying the wrong thing ? Everything about the lathe is dangerous !

2. I have not tried the 8mm boring tool yet. I am more inclined to use either a 6mm indexable tip tool or an 8mm brazed carbide tip boring tool. I seem to get good results when turning with brazed carbide. I have been told that this is quite common with beginners as the HSS tools need to be kept very sharp to get good results. The brazed carbide is a bit more forgiving.

John : you have lost me…why do I need a draw bar for the arbor ? (arbour ?). This is a parallel shank arbor to be held in the lathe chuck.

Edited By Brian John on 16/11/2015 10:55:12

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