Hollowing tools

[Holmes Anderson]

What hollowing tool do you prefer for excavating to about 6"?

[David Walser]

As with most things turning related, the answer depends on what I'm turning. For example, if I'm turning a something that is 'open', with fairly straight sides, such as a pencil cup or kitchen canister, my favorite hollowing tool is a scraper. I've turned a lot of boxes using my skew (flat on the tool rest) as a negative rake scraper. Using light cuts and a thick-in-cross-section scraper, you can hollow fairly deep. If I'm turning a 'closed form', I prefer to hollow with an articulated hollowing tool, such as the Elbo 2 Hollowing System. (My hollowing rig was made by a company that's now out of business.) Such a hollowing system allows you to use different curved-neck tools to hollow under the rim. It also makes it possible to use a laser or video camera to help hollow to a uniform wall thickness.

It also depends on the type of material being hollowed. For most woods, I have a slight preference for using a negative rake scraper. But, a traditional scraper will hollow more quickly (which can be a factor when working on a large piece). For turning resin or resin/wood blanks, my preference for using a negative rake scraper goes from slight to very strong. Negative rake scrapers cause much less chipping of the resin than do traditional scrapers.

HTH

[Richard Coers]

I suggest you do some research here. This discussion comes up about every other week. I prefer my DIY articulated hollowing bar with a DIY camera guide. I have about $40 in the entire rig, just $10 of that is the camera.

[Holmes Anderson]

Thanks, I guess some more info might be helpful. In 20+/- years of occasional spindle turning for furniture and stair parts I never had a notion of making bowls or boxes until I was given a bowl gouge so end grain hollowing is unfamiliar to me. I have been using the bowl gouge to hollow with push and scrape cuts but the depth of push cutting is limited in a kitchen jar type object with a 40/40 grind and even the scraping is a slow slog. I looked at old threads and see that scrapers are commonly used. I don't have any carbide tools but I gather there are flat carbide scrapers and more costly cup-shaped carbide like Hunter that will shear. I have been looking at the Sorby RS200KT and Trent Bosh steel scrapers. I couldn't find much user opinion on the Oneway termite. It seems like it could be a great tool but one youtuber suggested that it is difficult to find and hold the bevel. I can't quite picture how to hollow endgrain with a skew but would like to give that a try because I already have several skews.

[Thomas Wilson80]

I have a more expensive Hunter carbide and relatively expensive Thompson scrapers but find I most often use cheap scrapers that I have made myself out of hardened steel bars purchased online for a few bucks each. I also like the hurricane scrapers which are relatively cheap but hold a decent edge.
Tom

[Randy Heinemann]

I have Trent Bosch's hollowing tools but I believe they work best with his Stabilizer, which is an accessory for mounting the tools while hollowing. The whole setup makes it much easier to hollow, with less stress on your hands, arms, and shoulders. Together his tools and Stabilzer are a great setup but not inexpensive. I would also suggest doing research to determine what might work best for you. It's a tough decision these days with a lot more choices which makes the whole decision more complex.

[Richard Dooling]

I also have Trent's tools and they work very well in and out of the stabilizer. I don't have a cutter with me but I'd say the 5/8" and 3/4" dia. tool cutters are about 3/16" wide. This takes a very controllable scraping cut. The narrow cutter naturally is subject to less downward force than a heavier cutter and I find I can be fairly aggressive. They are capable of reasonably fine cuts but will need a finishing cut depending on the desired outcome.

[Brice Rogers]

Holmes Anderson, you asked about "excavating about 6 inches". I guess that it depends on the diameter of the turned piece and the angle of the inside wall. If I'm making something with straight in walls, like a pencil holder then I'll use a box tool rest that provides support for the entire 6 inch excavation. Or I might consider using my Eddie Castelein inspired articulated mechanism.

I guess that the tool I choose can vary. I think that the challenging part is removing wood and avoiding catches. If the opening is narrow, I might avoid a bowl gouge because the angles don't work. So, I might switch to a sharp scaper followed by a sharp negative-rake scraper. I also have a Hunter carbide hollowing tool that might work fine.

[Holmes Anderson]

Ok, so I didn't know there was such a thing as a box tool rest. This makes a lot of sense. I was working on straight-walled containers for kitchen use so about 3.5"-6" ID. I re-profiled a round nose scraper with a 45/20 negative rake and it works much better on end grain. I drilled a depth guide hole and then hogged out material starting from that hole with the flute of a gouge but my spindle tools can't reach deep enough. The handles will bottom out on the rest and the tools chatter before that because too much shank is in front of the rest. I found a video by Ernie Conover making kitchen canisters and he used what looked like a bowl gouge for the bottom 1/3rd of the hollowing. He said the last third of the hollowing is the toughest because each pass can only remove 1/16". I did the same thing and it takes forever and the surface requires much sanding. It would be so much easier with scrapers and a box rest inside the opening.

[Neil Strong]

Thanks, I guess some more info might be helpful. In 20+/- years of occasional spindle turning for furniture and stair parts I never had a notion of making bowls or boxes until I was given a bowl gouge so end grain hollowing is unfamiliar to me. I have been using the bowl gouge to hollow with push and scrape cuts but the depth of push cutting is limited in a kitchen jar type object with a 40/40 grind and even the scraping is a slow slog.

Most speciality hollowing tool setups are designed to solve the problems associated with small opening, undercut rims and long reaches off the tool rest encountered when making hollow forms. If you are just doing things like end grain kitchen jar/canister with wider openings that won't be undercut very much, or at all, you don't need any of the expensive hollowing rigs.

If you add something like an Irons Tool Rest to your current kit of tools you should be able to get the job done.

However, I wouldn't use a 40/40 grind on the bowl gouge to hollow out end grain and certainly not with a push cut. The 40/40 grind works best with a push cut when severing through cross grain fibres. You could try using it with that grind and a reverse pull cut inside but I think you will find that a sweptback grind closer to 60 or 65° will work better. A reverse pull cut with the bowl gouge working from the centre out will be cutting the fibres downhill, which works best when hollowing out end grain.

Starting with something like a Forstner bit for making a pilot hole will also speed up the hollowing process when working from the centre out.

You may need to do some scraping to complete the very bottom inside walls to get into the corner if you are going for straight sides and flat inside bottom.

If I was doing a lot of end grain hollowing in forms like that I would consider adding a hook tool like the one made by Michael Hosaluck to my tool kit.

[Neil Strong]

A reverse pull cut with the bowl gouge working from the centre out will be cutting the fibres downhill, which works best when hollowing out end grain.

Note: that is for hollowing in end grain!

I don't recommend that inside pull and/or scraping cut with a bowl gouge used on the inside of cross grain pieces, unless you want to live dangerously. To explain why see the following video by Tomislav Tomasic who explains this at the 16:30 mark...

See https://youtu.be/NZnSABnDAqs?t=984

[Brice Rogers]

One of the challenges when working with straight walls can be catches because of the significant overhang. I made a box tool post out of 3/8" x ~1-1/2" steel welded to a 1" dia. post. It can stick into an open by 5 or 6 inches and provides great support for whatever tool I'm using. Being the tool post is common steel (as opposed to cast iron) there is no chance that I could snap it off due to a catch. Here is a picture I grabbed from the internet of a commercial box tool post: