Thread: Deep hollowing tools???

Just as an observation on your tipped tools HSS, you'll get better control the closer the cutting point is to the shaft centreline. You could look at bending a swan neck in one or two of these as well.

And your rectangular scraper (2nd last pic) used narrow side upward, is rather like the Kelton designs.

[quote=rsser;1339560]Yes.

And with green timber the capped cutting tools are somewhat prone to clogging. Promforme less so than Munro.

Agreed it seems any covered tool has this problem . Although I am doing my darnest to get around the problem.

The Martel hook tool would be better but that's one that cutting blind with would be living dangerously or require a lot of practice

Yep, but very easy to make and if you practice on open bowls first it will be of great help.

And as an aside, Chinese M2 can vary quite a bit in quality. Something of a lottery.

Found this myself and gave away most of my Chinese M2. Poor HSS is a pet hate of mine.

Originally Posted by Ozkaban

Interesting thread, though I've never tried deep hollowing.

That is one serious looking lathe there. I'm having trouble working out the scale of it, but what is the bed height/length?

Cheers,
Dave

Wadkin, drool.

HSS, could we have more pics of your lathe and some specs?

Any lathe that makes drool, must be good

Originally Posted by Pat

HSS, could we have more pics of your lathe and some specs?

Any lathe that makes drool, must be good

ditto
or at least having a closer look at

Any lathe that makes drool, must be good

Naa that's not right.

You don't need a lathe.

A bit of chocky cake will do.

Cheers

Tim

HSS if I read it correctly you have reasonable size opening given that you are only doing 120 diam. which means you don't really need to angle the tool very much and you should be able to overcome the tool twisting action with either 1. an auxiliary handle or 2. use a gated hollowing system
But you do need
1. very small tip tools
2. have the tool rest as close to the opening as possible and/or use a hollowing gate.

From what you have said the pieces are more like 'vases', deep but not very wide. Think of turning inside no different than outside ( in regards to tool tip size) Most turning tools actually only cut on a very small contact area.

My best advice is to have a look at the Kelton web site, as they are one manufacturer that makes hollowers, in various sizes, and a gated hollowing system (that uses the hollowers and a hollowing gate for freehand use. Their ER handles also have a auxiliary side handle.

If you are thinking of using Tungsten tip tools (aluminium style cutters) (like Vermec and others) they can be very 'grabby' unless they are angled correctly and/or guarded, but then they clog. So, scraper type tips are often the best. IMO

By the way, on that lathe you should be able to turn ANYTHING!!! you just need the the right tools.

Ern,
Mcjings sell the tool unhandled as a ''flat holder and cutter''. It is half round with a flat side. The flat side gives it stability against wanting to torque when hollowing. The half round side makes it good for sheer scrapeing. They have a selection of cutters to fit and I also had some others at home. The others came from a much more expensive tool but work better on this one. At a rough guess the overall shaft diameter is 19mm but I have not measured it.
Regards
John

G'day, HSS.

For a cantilever beam of length L, with concentrated load (P) at the tip, the tip deflection is

d = P * L^3 / 3*E*I

E = Modulus of Elasticity (varies with material, ~30,000,000 psi for steel)
I = Moment of Inertia (depends on shape)

For a rectangular bar of width B and depth D,
I = B * D^3 / 12

For a circular bar of diameter D,
I = Pi * D^4 / 64

Cheers,
Joe

Good thread.

I have used the rig below to hollow to 350mm. It's a Munro head on a Hughie 22mm shaft + side handle to resist rotation.

I find I have to go above a 3/4" shaft for that depth/overhang.

The Munro head does tend to clog on green wood. As others have suggested, the Proforme head (Jim stocks them) has a better shaving escape topology for green wood.

I really like hook tools (the type you make yourself from cement nails) for deep hollowing green end grain. The shavings readily escape the cutter, there being no gate. They are not HSS, so get blunt, but I make and sharpen them in batches and just swap in a new hook when the current one gets blunt. You can also modify the profile to suit yourself. If I was better at tempering them I would stay with them, but I seem to end up making too many of them that are too soft or too brittle. A metal worker would have no problems getting that right.

Some people also re-profile old drills and the like to use as the cutters for deep hollowing.

If you are heading into deep hollowing territory check out this thread.

HSS - You are welcome to try the hollower below if you would like to give it a go...

Attachment 174763....Attachment 174762

or Hughie's Rip Snorter (I think it has a 1" shaft), if that takes your fancy.

Attachment 174761
.

Looking at some of those tools it is a wonder some of you gents do not just go out and get a 25pounder and blow the middle out of the trees you are turning. Honestly tho I have never tried deep turning, but it will happen one day I hope.

Well firstly, sorry about the late response to all your comments, I just haven't got myself organised enough to reply.

Attached are some photos of my lathe and workshop for those that requested it. It's a Wadkin RU 18 (sold to me as an RU 15 but I'm pretty sure it's an 18 as it has an 18'' swing over the bed)

The entire bed winds out on a rack and pinion, increasing the length between centres from approx 2.5m to 3.5m ish. This also creates a gap between the headstock and the bed allowing turning up to 1800 diameter between centres. Outboard turning max's out at just over 2000 diameter. The banjo weighs about 20kg, the free standing tool rest is about 150kg (currently being used as a heavy duty lamp stand), one of the face plates needs 2 people to lift it off the ground (visible behind the lathe). All up it weighs around 1500kg.

It's got a 3hp english electric motor and is geared rather than belt driven. It has 9 gears (100-1900rpm). The major draw backs are that all but the two highest gears are fairly slow, there is no variable speed and the gearbox is pretty noisy at high speed. Also, there is a carriage and tool post which is really invaluable for the work I do. The only problem is when doing short spindle turning, it gets pretty crowded around the headstock, with the banjo, carriage, tailstock and hand tools, all of which are inherently oversized and bulky. It's in mint condition but does require a fair bit of TLC (Inox, oil and grease) to keep the rust at bay and all the moving parts moving how they should.

Anyhow, back to the deep hollowing tools:

I like the look of your deep hollowing jig TTIT, awesome job! I'll think about doing something similar and might look at incorporating my carriage or tailstock somehow. I have a problem with some off-the-shelf accessories due to the 18in swing.

Cheers for the tips about capped tools and the kelton scrapers. I was looking favourabley at the woodcut hollower but I might have to settle for scrapers. After I made those tools I realised how much control you loose due to the torque inherent in having your cutting edge out from the centreline of the shaft (especially on round bar). I tried to counter this by milling a 12mm flat on the underside of the bars but it isn't enough sometimes. I didn't want to take more than 12mm off as I would loose too much meat.

Cheers for the formulas Joe, I'll try and apply these to what I'm doing. I'd like to be a bit more scientific about things!

Neil, I'd love to try out those tools and see how you're set up if that's ok. I'm down in Hindmarsh but I can come up anytime that suits you if that's alright. Likewise, if you're interested in what I'm up to you're welcome to check out the new workshop.

I'll definately try making my own hook tools but tempering I need to work on also, I've only done it once.

Cheers for all the responses,

John.

Nice shed.