Thread: Hollowing tools - which?

Originally Posted by tony_A

G'day Crock, I read somewhere that the commercially available articulated systems aren't as good for deep hollowing as a heavy captive bar due to vibration. Presumably this relates to the stiffness of the build as some of the articulated systems look a bit light. I find that once I get beyond about 200 mm overhang from the tool rest I start getting vibration. How deep can you go with yours in hardwood before you start running into problems. The design I have in mind would look something like yours but based on the "Kobra Hollowing System" using 2 knuckles built with something like 50 or 75 mm RHS and a 32 mm hollow bar that will hold a 16 mm hollowing tool. The 16 mm hollowing tool can be slipped inside the 32 mm hollow bar with about 100 mm stickout and the heavier bar run on the tool rest.

Tony

Tony

Tony, here is a photo of Trent's 20mm/ 3/4" total access tools including the new scraper I bought last trip and the extension bar I made. Yes they do sometimes chatter, but I made a micro adjuster for the height at the origin pivot post and by dropping the cutter height the base of the tool rubs and limits the cut. I have to admit to a very sphincter tightening moment on the 1st Camphor Laurel hollow form as it just hogged the wood out and was self feeding. It takes a bit of adjusting the speed of the lathe as well as the cutter height, but it works fine for me. Trent recommends using the straight tool, 2nd from the bottom to do 90% of the hogging out.
I can do 400mm/16" with it as in the original photo I posted and deeper with the extension in this photo, only limited by my bed length.
Why did I chose these tools?
The local woodturning competition limits the entry hole to 20% of the diameter of the piece and these worked the best. Not sure of the total weight of it all, but it's heavy and all the mass takes up the transfered forces. I saw a Simon Hope rig demonstrated at the Prossie Turnout and liked it and the Monster from the US, both good bits of gear.
As to your Kobra tool, I have not seen one in real life so not sure how it will handle our harder woods?
Rgds,
Crocy.

I too have gone down the Trent Bosch path. I don't use any support jig just yet but that's not to say i won't in the future. I find the 6mm carbide tip very easy to control and I would definitely recommend it to anyone wanting to get into hollow form turning.

Peter

I have a mix of free hand and captured systems 90% of which I have made my self. Mainly due to the fact I have found the bars are of a minimal thickness ... well from my perspective

So my main head type for hollowing is the Proforme from Woodcut. I have two heads one for roughing and the other set for a fine cut for finishing. Both of them are used on 20mm dia hardened steel shaft for maximum stiffness. They are ex linear bearing shafts and generally surfaced hardened and so can be worked quite readily.
I use the same dia on both hand held and captured rig is a type of Kobra with 3 or 4 knuckles, with either system I can get in around 400 if required as I am not much interested in going any deeper.
In order to minimise vibration over 250-300 I have a toolrest with a swiveling Irons Gate attachment set up, on the larger hollow vessel this gets shoved in about 3/4 of the way in to support the boring bar.

Sorry no images at the moment, the shed is out the back and it raining and darn cold. But I did post images up way back as I made this tools.

Having tried many of the so called hollowing tools, I fully endorse the earlier comment about the Woodcut hollowers, primarily because they use a capped elliptical cutter. Rollei Munro and the old Exocet use the same form. This means you can hollow across the bottom of the form and up the sides without having to repositon the cap over the cutting edge. Circular cutters with a circular cap have varying amounts of edge exposed so you are continually going from minimal cut to real 'arm hangers'.
I would avoid any tool that has overly complicated heads, with fine adjustment dials and so on, as these require a larger entry hole, meaning you are creating a vase not a hollow form. Nor am I a fan of scrapers, be they high speed steel or carbide.
Regarding side handles, I just turned a wooden handle, glued in a stub of threaded rod and this takes the place of one of the shaft locking grubscrews. And one tip on this, make sure the handle is horizontal when the cutting edge is horizontal, so you can use the handle as a reference for the cutter angle.

Originally Posted by hughie

Sorry no images at the moment, the shed is out the back and it raining and darn cold. But I did post images up way back as I made this tools.

Would appreciate a photo Hughie if you think of it when you are in the shed, no tearing rush. Found an old thread where you were talking about the Kobra and building one but its prior to the great photo catastrophe. I ran an advanced search using hughie as the author and hollowing as the topic then did the same search with NeilS. There is a heap of archival material that makes interesting reading, spent a couple of hours reading old posts.

Not sure if hey are available in your area but, if you get a chance to try the Easy Wood Tools hollowers, I think you'll be sold!

I actually have an easy wood hollower already - it's a handy tool for very tough woods (and epoxy), but not much good for deep hollowing.

Originally Posted by Lewie

Not sure if hey are available in your area but, if you get a chance to try the Easy Wood Tools hollowers, I think you'll be sold!

Yes, they are also here. Like a virus, Easy Wood Tools have spread everywhere. They seem to spread by infecting the novice and stifling their turning development from there on.

They are just a carbide tip screwed to the end of a bar. If curious, make your own. I made my own version but only occasionally use it on dirty root balls (with stone inclusions) and the like.

I consider them to be a tool of last resort.

But, a bad habit to get into if used as a primary turning tool by novices. They will, IMO, stunt your turning development.



Sent from my ZTE T84 using Tapatalk

I totally agree with you Neil. it's not woodturning
Cheers Mick

Originally Posted by NeilS

Yes, they are also here. Like a virus, Easy Wood Tools have spread everywhere. They seem to spread by infecting the novice and stifling their turning development from there on.They are just a carbide tip screwed to the end of a bar. If curious, make your own. I made my own version but only occasionally use it on dirty root balls (with stone inclusions) and the like. I consider them to be a tool of last resort. But, a bad habit to get into if used as a primary turning tool by novices. They will, IMO, stunt your turning development. Sent from my ZTE T84 using Tapatalk

Actually, I've found there isn't anything I can't do with the Easy Wood Tools (except sharpen them). My turning abilities have expanded with their use. Their new negative rake cutters are perfect for acrylics.

Originally Posted by mick661

it's not woodturning

I'm not sure that I would go as far as that, Mick...

But what I can say is that last year I spent ten days with a bunch of the best woodturners in the world who had hundreds of turning tools between them and I didn't see a single Easy Wood tool among them. That must say something.

It is probably time to have another discussion about cutting vs scraping, which is what Easy Wood tools do, but this is not the thread for that. I might kick that off in a few weeks when I have a bit more spare time.