How to turn really hard wood ?

[woodfarmer]

And I don't mean wimpy stuff like old oak beams which are soft in comparison to the 115 year old greenheart I am trying to turn.

My bowl gouges won't go near it, can get the odd dig but no real "cut". The only thing I have been able to use to make any progress is using my skew chisel as a negative rake scraper, and I have to sharpen that frequently, like every 5-10 minutes.


I cant see why a gouge presented at the right angle with a cutting edge wont cut, but a scraper will.

 

[Dalboy]

How about trying carbide tools

 

[marcros]

cant help on the tools, but watch out for splinters- they normally turn septic.

 

[Doug B]

How about trying carbide tools

+1

 

[CHJ]

How are you sharpening your gouges, the minutest rounding of the bevel edge will present a blunt cutting edge that wont penetrate the wood.

Not exactly a rounded bevel in the above sketch but it shows the principal, something easily achieved in error by folks trying to hone a turning gouge on a leather wheel for instance.

The above would also explain the tool diving in at times when the edge bites without any real bevel support.

A scraper will have a sharp edge because the narrow front face will be most unlikely to have any rounding and you are not attempting to rub the bevel.

 

[woodfarmer]

How are you sharpening your gouges, the minutest rounding of the bevel edge will present a blunt cutting edge that wont penetrate the wood.


Now you will criticise....

I use the flat end face of the wheel to grind, the gouges rest in a long Vee groove that is fixed (at 45 degrees to the face of the wheel). so I just rotate them as I grind. little light touch /rotate.

they have been fine up until today.

Even my round nose scraper does not work, either no cut or a dig in. ONLY the skew works but then only for a very short while and removing very little, but they are shavings, not dust.

 

[JimB]

I remember seeing a Grand Designs programme where they had to put greenheart through an industrial bandsaw. They had to keep changing blades.
Have you tried grinding a less acute angle on a gouge to see if it helps?

 

[RogerP]

Of course it depends on exactly what you are trying to make from the green heart. If at all feasible I'd put it on a metal working lathe and treat it as brass.

 

[duncanh]

As already suggested - try some carbide tools. Either buy them ready made or just buy the tips and make your own.
Alternatively, find some harder than usual HSS and make some scraper tips (I have some made from some unusually hard planer blades).

I don't often turn exotics but I've had several where my regular gouges didn't work well - I think lignum vitae was one example. In the end I used a scraper.
If the skew is working then try sharpening your scrapers at a much more acute angle. Also try honing the edge so that there's no burr - does it make a difference?

Sharpening 5-10 minutes isn't as bad as the time I turned gorse - very abrasive and not something I'd want to repeat.

 

[Nick Arnull]

Hi I would recommend shortening the bevel on your gouges and use negative rake scrapers,Progress will be slow but should work I would also recomend a slower speed to do the initial shaping.

 

[bugbear]

I'd try to find some (probably old) info on ornamental turning.

They work in boxwood and ivory (and other exotics) as a matter of course, and some of their techniques
might be transferable to a plain lathe.

BugBear

 

[woodpig]

Only tried it once but soaking difficult to turn woods in a 50/50 mix of water and washing up liquid is a trick I've heard once or twice. Not a quick process though as it may need to soak for a couple of months then let to dry a little for a week or two. Worked for me though on some 300 year old oak.

 

[woodfarmer]

At slower speeds I can remove material along the grain, but they wont look at the end grain. At least I now know how to turn oval shapes

Using carbide tipped tools I get sometimes get the odd few sparks. Bit scary in the dusty wood lathe shed

When I first had it cut down into 5 inch square sections from the ex pile from Par harbour, there were sparks a plenty flying off the 6 foot diameter carbide saw teeth driven by a Ford 6D diesel engine.

I have made some progress along with more than a few trials and tribulations.
It was just a little bit too big to put in the Holbrook so I had to angle grind it smaller. Bit sad because I spent two days getting a good finish to the outside of the bowl, now lost.
The new tin of beeswax isn't. It is some kind of white paste and leaves a very anaemic looking finish.
There was a split just where the rim was to be so it isn't anything like as deep now.

Plus a good few other things...

Given the choice I think I would rather have turned it from EN316 stainless, it would have been easier.

Attrition is my friend.