Hollowing tools

Hello, Gerald, I'll leave the more eloquent salutations to others, but to say welcome and good luck with your disease. Since I have a few moments while waiting for glue to dry I'll respond with my limited experiences on the subject. I'm sure I'll be pounded for any inaccuracies, but here is my 2 cents worth:

Different type of hollowing call for different tools and techniques. I'm still working on acquiring that elusive perfect 1-step hollowing tool that allows for fast, drama-free, smooth hollowing in all situations. I haven't found it yet.

For end grain, ring and hook tools seem preferable. I have only tried the Termite. You may reputedly make your own hook tools, but I have not done so due to a lack of metal stock, anvils, heat sources, and metalworking tools generally. The termite cuts pretty well, doesn't seem prone to catch easily, but does require adapting to its peculiarities. The hole clogs easily although the larger ring is less susceptible; yet larger ring is more prone to grab. It seems to hold an edge well. Comes with a cone sharpener that must be used in a router (and preferably with a table of some sort). The Termite doesn't seem to care for non-endgrain. I keep a 2x4 with an 8D nail driven through it nearby when using the Termite to clear the pack-in shavings from the ring. The replacement bits aren't cheap, IMHO.

I also have a homemade straight Oland tool, and a swan neck Hollowmaster. The HM comes with a round scraper and a profiled tool bit. They both work pretty well, although you have to watch the scraper's angle/positioning around abrupt wall profile transitions to avoid grab. The HM's scraper diameter is also too large for small radii. The swan neck makes it easier to reach hollowed vessel undercuts that you cannot get to with a straight tool. They sell (and you can build) articulated tools that use steel lathe bits like the Oland tool (and the HM bit) and if I were to buy or build another tool this would probably be the one; possibly combined with an arm rig and/or steady rig (i.e. Scorpion, et al.).

The tool bits which come with some hollowing tools are really overpriced metal lathe bits, some with a custom profile that you could duplicate or modify on standard off the shelf bits. For instance, a standard metalworking 3/16" or 1/4" tool bit costs less than a dollar, yet a HM replacement bit, if I recall correctly, costs around $16. Never bought one and probably never will. The rub is that the bit holder has a half round profile which the tool bit's cross-section mirrors. It can be modified or replaced so that standard bits may be used on the swept handle.

With the HM, I generally do the majority of hollowing with the tool bit, fair the curves with a scraper, and sand - starting with 180-220 grit. I used to start finishing with an 80 grit gouge (sandpaper), but found that leaving a smooth finish from the tool was much preferable, less time consuming, and generated less dust. The sanding scratches from coarse paper take longer to remove with subsequent higher grits. Even with persistence and care, a missed 80 grit scratch usually shows up in the finish application stage; thus I've pretty much stopped using really coarse grades of sandpaper unless absolutely necessary.

The prices for various commercial replacement scraper options vacillate wildly - all the more reason to DIY if possible. There are a number of scrapers which are sold for box bottoms and corners, and for fairing bowl profiles - both inside and out, and even cutting dovetailed rims for a chuck to bit into. I generally grind my own from the extras (the ones I never used) in a set of cheap HF tools. They work fine. My favorite is a round nosed internal bowl scraper made from the 1" skew. I've seen scrapers made from old files, but files are brittle and should not be used as cutting tools. Homemade scrapers can be installed on a tool like the swan-neck HM by simply grinding the desired profile and drilling a hole (with a carbide bit in the case of old files).

I've not tried carbide bits in either tool, but I am not adverse to trying one. I would imagine that they hold an edge longer, but be more difficult to sharpen. Old flat work rumour has it that steel can be honed sharper than carbide, but doesn't hold up as nearly as long on saw blades and such. New abrasive technologies may have rendered this invalid. As well, turning seems to be a slightly different paradigm with respect to sharpening, refreshing, and edge life.

There are a number of sites on the Internet which depict the fabrication, sharpening and use of various tools. Here is one:

I'm sure Darrell will respond shortly and also point you toward his site, which has a lot of useful info. As everyone develops their own techniques, let experience be your guide. YMMV. And just think, you just wasted 5 minutes of your time reading this rambling collection of random thoughts - time that can never be reclaimed...

Greg G.

if you are making boxes and doing just a little undercutting, you don't need special tools and hollowing rigs and all the other paraphanalia that you can spend money on

1. I really like the Soren Berger tool for making square bottom boxes - it's really optimized for that purpose - however, a bowl gouge and a square nosed scraper will do almost as well

1. for light undercutting, as long as you don't need more than about an 85 degree angle to the center line, just use the bowl gouge - if you need more than that, you will need somethihng with a bend in it - my favorite tool for that purpose is a piece of 3/4 inch cold rolled steel with a short extension at about 45 degrees that is in reality a 1/4 inch bowl gouge - that lets me undercut quite significantly - but beware that it can really really catch if you aren't right on top of it and get the angles wrong

2. a gouge bent into a hook will work just like number 2

1. a bent scraper is more forgiving

I, as others, use a gouge with a fingernail grind for undercutting. Just remember that the downhill direction is from under up to the rim when you do that, and you'll be happier with the result. Means cutting down from the bottom of the curve into the center of the bowl, and up to the edge.

I use a pointy-grind gouge for hollowing deeper. It's Darrell's Oland tool with a flute, and corrals the shavings into a good flow out and down. The main problem with scraping cutters is that they choke on their own waste. With an undercut, the curlies won't flow over the rim on their own.

Hooks and rings and Hunter tools are all pretty much the same, gouges at 90 degrees to the handle. The hook has an opening for heavier cut shavings to flow through, the ring is closed, and the Hunter must turn a modest shaving tightly in the gutter around the edge. It's a metal-working tool adapted to wood, which is why the carbide. From my experience with carbide metal-cutting tools, they cut pretty well for a long time, never as well as a good steel edge, though.

One other type is the shave-type cutting tool, where an edge is depth-limited by a throat which the turner sets. Never used one for any length of time, but the theory is good.

Hello Gerald,

A couple of years ago, Lyn M. wrote an extensive multi-part report on hollowing tools. The articles are located at my web site. You can access them at the following link . Lyn did post regularly to this newsgroup, but he became ill a couple of years ago and has not been able to do much lately.

There are some new ones that have come out since those articles were written. The Hunter Tool, a carbide cutter, and the Eliminator, also a carbide cutter. Both of these latter tools are excellent endgrain cutting tools. I also have a stabilized hollowing tool manufactured by Vermec in Australia which is easy to set up and does an excellent job. Also, while at the Irish Woodturning Guild annual meeting in Ballina, Ireland in October I got to see the Vicmarc hollowing system, which seems to work very well.

Good luck with whatever tool(s) you select.

Fred Holder

Hi Gerald, Good post that's prying up some good responses.

One way to evaluate tools and gadgets is to look at past and current catalogs. What's not advertised in current catalogs that was listed in years past is probably something that few turners are using. I figure that perennially advertised tools work, so let others use and misuse a new tool for a while before you buy it. Hollow with whatever tools you have, using whatever techniques you know. As has been said before, "hollow end grain anyway you can". :)

For hollowing boxes, you might want to wait a while on specialized tools and just drill a hole in the end grain to finish depth, widen out and shape the cavity with a gouge, undercut the neck with a 90 deg. or greater inserted bit tool, smooth with straight and curved scrapers and finish up with sandpaper. BTW, I think most commercial small swan neck tools are too flimsy, designed to hollow maybe 3 inches, but since the swan's neck can't be on the tool rest it adds to the overhang.

Another approach might be to look in catalogs or a friend's shop and choose what hollowing tool makes sense to you from the many options, then make or buy your choice. With so many size, grain, form, tool, method, cost and experience variables to contend with there is no one best. Pick one that suits you and try it, no matter which one you pick or find satisfactory, you'll want to try a different one soon, then another. It's a shame we can't exchange our used once and discarded tools to satisfy each other's tool curiosity. There would be plenty to go around without buying or making any more culch. IMHO, if a tool requires a "learning curve" that's a lot more difficult than learning the usual turning technique, something's amiss.

BTW, I believe that it's right to emphasize good tooling, but In a way, sanding as a tooling effort is becoming the "no-no" of the 2000's, sort of like scraping was in the 1980's or the "great skew-scare" of the

1990's. Scraping is now very legitimate and skewing is very popular while use of the "80 grit gouge" has become laughable or suggests incompetence. Nevertheless, abrasives are cutting tools.

Turn to Safety, Arch Fortiter

I want to thank you all for the posts as Arch said it is "prying up some good responses."

I will review all said above and try to build some of my own (thanks to Darrell) and may even try to grind the Berger tool profile (thank you William). I have access to a small metals supplier and a Harbor Freight for the HSS blanks & carbide they sell for metal lathe work.

The local club here in Ventura County has been very helpful and they may facilitate that tool trade plan Arch mentioned above. They do offer mentoring for turners like me trying to find their way

I want to let you all know that an undercut maple bowl I just made for my wife started all this. I just knew there must be a better way than the chatter I saw (and had to remove) while making this bowl. It is only 3" deep but the wood moved or the tools because it had ridges (from chattering?) around most the inside surface getting worse approaching the rim. It was not too thin at 3/16" but it took sanding to 1/8" before I got it smooth. Thank you all again,

Gerald