# Making hollowing tools



## Phil Pascoe (9 Jul 2014)

I've been trawling evil bay, looking for ideas for when I come to make my own hollowing tools. Is there any merit in using hexagonal bar? I can see the theory, but has anyone tried this?


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## Vic Perrin (9 Jul 2014)

Personally I have always used Square Section bar which gives you that extra stability on the tool rest particularly when you are doing a deep hollow form.

Vic


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## Phil Pascoe (9 Jul 2014)

Thanks Vic, I can see this but is there any point in going for hexagonal bar - you've still got a flat underside, the downside being that pressure is slightly off centre if the tip is skewed, the upside being that the tip can be skewed and still have support. For the cost of making them I might make both, the main cost being the tips.


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## Vic Perrin (9 Jul 2014)

phil.p":55q3waev said:


> Thanks Vic, I can see this but is there any point in going for hexagonal bar - you've still got a flat underside, the downside being that pressure is slightly off centre if the tip is skewed, the upside being that the tip can be skewed and still have support. For the cost of making them I might make both, the main cost being the tips.



As you say Phil the tools cost very little to produce and an hexagonal bar might prove to be ok.

I don't know whether or not you have made any yet but I can assure you that if you haven't you will be well impressed on how they cut.

God knows how many different turning tools I have, but since making these carbide tipped tools they seem to have become my first choice especially for roughing out and end grain hollowing. 

I have also made some carbide tipped tools for my Lyle Jamieson Hollowing Rig and have really improved how that system cuts.

Vic


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## duncanh (10 Jul 2014)

Every tool I've made has been round bar except one which was square. I always use the round ones for hollowing. They give me far more control and allow me to rotate the bar and ease into the cut. More often than not I will rotate the tool during use to ensure the most efficient cut.

The square tool I made is useful for roughing down the outside of logs but that's about it.


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## Phil Pascoe (10 Jul 2014)

I can see the beauty of the solidity of a square bar when roughing and maybe a square bar with an angled tip for taking the final light cut, but I can see that the manoeuvrability of the round bar would be advantageous in other situations. Anyone going to disillusion me?  
I think when the time comes I'll just make and try everything.


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## chipmunk (11 Jul 2014)

Hi Phil,
I have made my own tools in both round and square, as well as having a Big Brother with a round shaft. 
I like HSS cutters rather than TCT ones - they're easier to make and sharpen IMHO - but each to his own.

Provided the square shafts have rounded corners it really makes little difference in use. However, it does help with reminding you of the orientation of the cutter when it's lost inside a vessel out of sight.







These are all mild steel and bending the swan necked tools is pretty straight forward if you heat the point of bend to dull red and then tweak it round - remeber to have the cutter in line with the shaft to prevent big turning moments in use.

I also have some square shafted tools with the cutters mounted at 45 degrees to the edges for shearing cuts like the Sorby tool here...






HTH
Jon


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## Phil Pascoe (11 Jul 2014)

Brilliant! Thank you. How do you find the angled tipped one to use?


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## chipmunk (11 Jul 2014)

Phil,
The angle tipped tool is very good for finishing cuts but it's not a heavy-duty hollower. 

For bulk hollowing you don't want too broad a cutter as it can be grabby. The Sorby No 8 cutter style are my favourites for real hollowing scrapers in smaller sizes and the No 4 bullet cutter in larger sizes. http://www.stilesandbates.co.uk/browse.php/section/6541/level/4

I used to buy these but I now make them from 1/8"x5/8"x4" HSS toolbits from ArcEuroTrade... http://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/High-Speed-Steel-Toolbits

Cut with Dremel cut-off tool, drill a 5mm hole with a high quality spade TCT tile drill and shape flat on benchgrinder platform. As an alternative to drilling you can cut a 5mm slot in the back with a Dremel or an angle grinder.

HTH
Jon


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## Phil Pascoe (11 Jul 2014)

Thanks - I've stored those links. It'll be a while yet before I get to making them, but I like to get the thinking done first. It's cheaper that way.  I'll post them when I'm done.
Phil


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## robinthebevel (24 Jul 2014)

Hi Jon... and everyone else...

New to turning and brand new to this forum.

Just wanted to say a quick thank you for the link to the tool steel supplier! Been trawling the internet for ages before I found your post.

Cheers!


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## Melinda_dd (4 Aug 2014)

As someone who hasn't used a hollowing tool, what is the difference between a hollowing tool and a Robert sorby multi tip scraper tool...

Please dont laugh
..never even touched a hollowing tool


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## Random Orbital Bob (5 Aug 2014)

If the Sorby tool in question has a long and robust stem then not necessarily anything other than perhaps a swan/goose neck for the difficult access in the upper "corners".

Hollowing tools come in a variety of shapes but the access and long hang over the toolrest are two unavoidable problems that usually drive the design in the direction of chunk (handles often as well as stems) and swan necks.

The tips include quite a range.


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## bogmonster (5 Aug 2014)

First off, yes, certainly have a go at making your own. Simple hollowing tools can be very easy to make. Hexagonal bar is almost always tool steel of some variety. Unless you are going to incorporate the cutting edge into the same steel as the shaft then I would avoid unless you really know what you are doing and even then I would still avoid.

New tool steel stock is supplied annealed. Unless it is an exotic such as an air hardening steel then it is reasonably easy to work but there will be limited advantage to it over mild steel in its annealed form. You would need to harden and then temper the steel to get any real benefit from the tool steel. This is difficult to achieve in the home workshop for anything other than ends of tools or small pieces. Certainly very difficult for a 2 foot tool shaft. The implications of screwing up can be dangerous if you end up with hardened sections that you have not tempered as they can shatter (this is why you should never sharpen files and use them as chisels on a lathe as they are too hard and brittle).

By all means have a go at making your own cutting tips. A piece of ground flat stock (usually O1 or similar steel) is a good place to start. Can be worked with hacksaw, file and good HSS drill bits. Can be hardened with fire bricks and a good propane torch or better still a MAPP gas torch. Quench to harden in oil for GFS or O1. You can temper in your kitchen oven but make sure you use an accurate oven thermometer and I recommend you quench in veg oil if this is your plan. There is loads of info on the internet on this topic.

This link has some tooling I made from GFS (only the dies, the frame s MS, and in these pics pre-hardening and tempering) - use the back and forward arrows to see a couple of other pics. These are 1" x 2" x 4" so too big for most people to tackle at home without special equipment.

https://www.flickr.com/photos/[email protected]/14175729906/in/photostream/

BM


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## Walney Col (5 Aug 2014)

There's some great pointers in this thread, thanks everyone.


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## chipmunk (5 Aug 2014)

bogmonster":2wkxdcdf said:


> Hexagonal bar is almost always tool steel of some variety.



That's a bit misleading IMHO. Mild steel hex bar is very readily available for making nuts and bolts.

Jon


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## bogmonster (6 Aug 2014)

Yes, I'm sure you are right Jon. Appologies for any confussion caused.


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## finneyb (6 Aug 2014)

The easy way is use a piece of 6mm Square tool steel http://www.rdgtools.co.uk/acatalog/Squa ... -hss-.html
Put in the end of a 20mm carbon steel rod - mine's about 2ft long - with an extension handle for deep hollowing.

Snap the tool steel to length - score with a file and snap with pliers - use eye protection
Grind the end that's going into carbon steel approx. round.
Drill end of carbon steel and fix tool steel with superglue - if you need to change the tool steel heat breaks the glue bond.
Grind the cutting edge as you desire.

Brian


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## duncanh (6 Aug 2014)

I still don't see the need for hex or square bar. Round is much more controllable for getting a better finish. Almost every hollowing tool on the market is round.


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## xraymtb (6 Aug 2014)

Would square bar not give better control in circumstances where the cut is being made to one side? For example if the cutting tip projects at an angle sideways this will exert a rotational force on the bar which the square bar counters better? 

I have some DIY carbide tools and square bar makes keeping the cutters level easy (although makes a shear cut with the cutter at 45 degrees much harder)


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## Phil Pascoe (6 Aug 2014)

Unless of course you offset the cutter as Chipmunk has done. It's two tools instead of one I suppose, but if you're using carbide cutters, the main cost is the cutter rather than the rest of the tool.
Your last paragraph sums up what I was getting at - if hex bar were used, would it be a worthwhile compromise? I suppose logically the cost of making the tool is small enough to justify making all combinations of bars and cutters, then keeping the ones that suit best.


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## CHJ (6 Aug 2014)

duncanh":24w1y1fb said:


> I still don't see the need for hex or square bar. Round is much more controllable for getting a better finish. Almost every hollowing tool on the market is round.



Some confusion here on use of the different shaft forms methinks.

Round tool shaft does give angular flexibility for use with tips intended for shear cutting/scraping as a finishing cut, and shielded or ring cutters needing angle of attack adjusting in use.

Square tool shafts come into their own if you use the tips much as I do the majority of the time in plain Boring mode for rapid removal of internal waste and external rough truing and shaping of a blank.

Used for this type of cut external or internal, a square shaft is ideal for tool stability.


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## finneyb (6 Aug 2014)

Lyle Jamieson a US turner, wood sculptor etc has an article for building your own hollowing rig, if you want to go deeper than say 5". https://www.lylejamieson.com/tools/tool_howto.asp

Site is worth a look around also

Brian


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## duncanh (6 Aug 2014)

No confusion at all. With a round bar you can control how aggressive a cut you take, whether it be roughing/boring or shear cutting/scraping. A lot of my hollowing is done from start to finish with the Munro tool (because I can take large cuts for roughing and tiny cuts for finishing) but I also use flat cutters (which can also be used as shear scrapers) and toothpick style cutters (either from Sorby or home made from HSS).
If you use a round bar you can vary the cutting angle and roll into the cut, helping to avoid catches. This is particularly useful when inside a closed form where you can't see the cutting tip. Also, if you've done most of the hollowing with a flat scraper on a round bar it's simply a matter of loosening the bolt, rotating it slightly on the tool to then use it as a shear scraper.
Maybe it's just because that's how I first started hollowing, but I've never seen the need to buy square stock when round serves me perfectly well.

The only time I use a square shaft tool is when I rough out a large well out of round log using a 1m long square bar with a square carbide tip. 
I have a couple of Sorby tools (RS200? and cranked version) but hardly use them for hollowing anymore (although that's partly because I tend to make larger forms beyond their reach).




CHJ":8rb50vzw said:


> duncanh":8rb50vzw said:
> 
> 
> > I still don't see the need for hex or square bar. Round is much more controllable for getting a better finish. Almost every hollowing tool on the market is round.
> ...


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## graduate_owner (17 Oct 2015)

Another really useful guide. Thanks guys.

K


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## chipmunk (19 Oct 2015)

Well I have a bit of a confession to make. I have since tried Simon Hope's little 6mm round TCT cutters and have become a real convert. 

Simon's are circular TCT positive rake uncoated indexable tooling tips intended for Aluminium mounted with an M2.5 torx screw on a short section of 6mm bar which can be held in the end of a hollowing bar like these.





I bought a bent tip from Simon and then knocked up some straight tipped versions based upon a slightly different cutter tip from APT which woodpig had suggested (https://www.ukworkshop.co.uk/forums/post989253.html#p989253). To make these you need a 6mm end-mill to create a flat bottomed seat centrally in the 6mm rod and then drill and tap an M2.5 hole right through on the same centre. Finally saw, file or machine away the end of the rod to expose the cutting edge. A flat on the 6mm rod makes it easier to mount and unmount without binding in a 6mm hole in your boring/hollowing bar. 
I can mount these in some hollowing bars I've made for my Monster knock-off hollowing rig (http://i1298.photobucket.com/albums/ag49/jonathanagibbs/IMG_20150818_194154894_zpssxq3uond.jpg) or a short wooden handle and I also have a couple of mild steel flat stock holders with a 6mm mounting hole so I can use them directly in the Big Brother shaft in place of the HSS tips.

Here are the APT parts references (http://www.shop-apt.co.uk/carbide-tips-hobby-use/pack-of-2-rcgt-0602mo-alu-ak10-carbide-tips.html) and a sharpening gadget comprising a 6mm rod threaded at the end M2.5 so that a diamond file can sharpen the cutter easily as it rotates under power.






HTH
Jon


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## woodpig (19 Oct 2015)

They don't get much easier to make than these:

http://www.fromthetree.co.uk/hollowing-tools.html

Inexpensive to make as well.


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