Hollowing Cutters

[Edward Weingarden]

I recently started to do some hollow forms with a homemade articulating arm setup. I'm using a piece of 3/16" square steel, with a curved end, as a scraping tool. I've only turned two pieces thus far, and found the hollowing process slow and tedious. Would a carbide cutter work better? What shape should I use for getting the bulk of the wood out? Should I be doing something different, or is the hollowing process slow and tedious, regardless of whether using a scraper or a cutter? Thanks.

[Thom Sturgill]

Several issues here - you said 'square steel' is is HSS? Almost all hollowing is scraping and scrapers need sharpening regularly. Carbon steel will lose its edge very quickly.

Secondly size matters - a 1/4" cutter will take a bigger cut than a 3/16" cutter and thus will hollow faster.

Are you hollowing green or dry wood? Dry will cut slower than green....

Are you letting shavings pile up inside? They can get between the cutter and the wood and need to be removed regularly or they can cause catches and other problems.

A carbide cutter will generally cut better and will leave a much cleaner surface. I prefer one that is cupped and mounted at a 45 degree angle for shear cutting, but also use square HSS cutters and disks and teardrops depending on where I am at in the process. It helps greatly to drill out the center to depth even if its only a 3/8" hole. Fighting the center takes a lot of extra time. Being able to start a cut at the hole and sweep toward the outside is the fastest.

[Edward Weingarden]

Thom:
The scraper is HSS. I'm turning green wood thus far. I stop to get the shavings out when I sense they're building up. Can you tell me the shape of cutter you're using at the different stages of the hollowing process. Thanks.

[Scott Hackler]

Every hollwing tip I have is shaped exactly the same, rounded. The cutter should have a bur on it and you should be checking it regularly and refreshing it with the grinder or a diamond hone. For me I use the hone while still in the boring bars and with a downward stroke...in one pass... I go completely around the edge. Works very well. Every once in a while I will remove the bur and start over.

Carbide cutters like the hunter cups cut extremely well. Almost to good, because they will remove a lot of wood if you dont approach the wood with the cutter at an angle. But... they can't really be sharpened and are just rotated to get a sharp surface again. They do stay sharp for quite a while though (unless you are hollowing a wood with a lot of dirt (buckeye) or with a high silica content (osage orange).

I use HHS cutters 95% of the time and still hand hollow any thing under 4-5", but the hunter cutter I have for a deep bar makes me want to "upgrade" the cutters on my Bosch bars to the carbide cups for a real smooth interior.

[robert baccus]

There is one cutter that cuts shavings as big as a 5/8" gouge--no scraping and very fast. Check out the Woodcut cutting tip. Been using one for 20 years doing vases to 20".

[John Sincerbeaux]

I like the Monro Articulated Hollower2. The carbide cutter seems to stay sharp forever. Just rotate the cutter occasionally for a super sharp edge. Also you can adjust the links for your desired "angle of attack".
I usually need to stop the lathe every 30-45 seconds to clear the shavings.
I don't use the shield over the cutter.

[Thom Sturgill]

Thom:
The scraper is HSS. I'm turning green wood thus far. I stop to get the shavings out when I sense they're building up. Can you tell me the shape of cutter you're using at the different stages of the hollowing process. Thanks.

I have a large flat round cutter and a teardrop cutter that I use for smoothing the interior and getting ridges out. I will switch between the Hunter style cutters and the rounded square cutters depending on how well the wood is cutting. As others have said, the Hunter cutters can be too aggressive and the square cutters can be too slow depending on the wood and how good a burr you have.

I haven't tried the Woodcut or Munroe cutters so I can't talk about them, but have tried the termite and hook tools. Both have their places, especially dry wood for boxes.

[Edward Weingarden]

There is one cutter that cuts shavings as big as a 5/8" gouge--no scraping and very fast. Check out the Woodcut cutting tip. Been using one for 20 years doing vases to 20".

The Woodcut site shows a few different options (e.g. Scraper Cutters, Hook Cutter). Which one are you using? Thanks.

[David Delo]

Edward,

Yes, hollowing is a slower process, that's just the way it is. Certainly nothing like using a 5/8" bowl gouge to hog material out. Here's a couple pics of the cutter shapes I use.
From left to right:

1/4" HSS straight cutter (probably like the one your using only bigger). This cutter seems to remove the most material but I have a harder time producing a nice surface with it. Very easy (for me at least) to get divots when trying to blend in the final thickness passes. I sharpen this cutter on CBN.

Round HSS cutter seems to work best for my skill level and technique. As long as I can get the cutter in the hole, this cutter is becoming my go to cutter from the beginning of the job. I sharpen the top of the cutter upside down on a 300/600 diamond card.

The teardrop is a HSS/Carbide combo material. I sharpen it the same as the round cutter. Maybe not as sharp as the round cutter but the edge does last longer. I use this at the bottom of my vases and also to smooth out cuts from the straight cutter.

#1 Hunter Carbide bit. As you can see it's a round cupped cutter tilted 45 degrees and as others have said, can be a very aggressive. I've used it a few times but have put it back in my toolbox, just waiting for that once in a decade special wood find.

Had a chunk of wood on the lathe that I was going to turn into a jam chuck but decided to hollow out after reading your post. Just some very dry glued up poplar that I used the round cutter on. Not perfect but not alot of sanding would be required to finish it off. Try one and see how you like it.

Carter Cutter 1.jpgCarter Cutter 2.jpgCarter Cutter 3.jpg

[Edward Weingarden]

Thanks for the photos David. A picture(s) speaks a thousand words.

[robert baccus]

I use only the $85 cutterhead and mount it on a homemade control bar. They sell many articulated versions now as well s handles ect. The old original cutterhead I use is also jam-proof(except wet aspen), unbreakable, long lasting and is sharpened with a diamond stick in about 30 seconds. This cutterhead has a brass limiter making it cut like a safety razor hence no catches. It is actually a heavy built hook tool with a limiter.

[robert baccus]

I use these also to trim up around the vase lips but these are stone age for removing a lot of wood wood smoothly.

[David Delo]

I use these also to trim up around the vase lips but these are stone age for removing a lot of wood wood smoothly.

Robert,

What other style cutter would you use instead? The vases I make are usually 10" to 13" deep. Might be some variations as to the radii of different mfg.'s cutters but if your aware of something different, let me know.

Dave

[Thom Sturgill]

Robert,

What other style cutter would you use instead? The vases I make are usually 10" to 13" deep. Might be some variations as to the radii of different mfg.'s cutters but if your aware of something different, let me know.

Dave

Robert uses the woodcut cutter which is a HSS hook tool with a brass cover that limits the cut and prevents catches. Hook tools are excellent at endgrain hollowing. I have made some carbon steel cutters and like them and may well end up buying their cutter and bar though I would have to adapt the 1/2" bar to fit my 3/4" handles and rig.

[David Delo]

Thanks Thom, Very interesting indeed. I don't know how I missed Robert's explanation above the first time.