Finish turning the inside of hollow forms??

[Reed Gray]

Well, Kathy, this is all your fault. After that last Myrtle vase, I had to try a few hollow forms. The biggest problem I have had with them is getting good clean cuts on the inside, and getting a smooth even surface. I have been making some canisters, and other more open forms where you can see the inside, but getting the smooth even cuts had eluded me for a long time.

I have the McNaughton hollow form cutters, and they are great for roughing work, but not for smoothing. I have tried the tear drop type scraper tips, but they always seem to be very grabby, no matter how delicate I try to be. I have an Eliminator with the concave carbide disc, and it works, but again, I can't get the insides as smooth as I want getting a more washboard type end product. I have a ring type tool with a chip limiter, and it does cut clean, but still, to much up and down.

So, any hints? Any tools that I just can't do it without?

robo hippy

[Brian Kent]

50 grit gouge? :)

[Dan Forman]

I haven't tried it yet, but I think a tear drop scraper with a negative rake would be the ideal - that would take care of the grabby issue, while providing a broader edge which would be best suited to get out the ridges (washboard) that most small radius cutters leave. Do you hollow free hand, or have some sort of captive or articulated arm system?

Dan

[Glen Blanchard]

This, from Mike Jackofsky's website referencing his hollow-pro scraper (when used with his his hollow-pro hollowing tools)..........

"Made from high quality M4 powdered metal, they are sharpened with a 75 degree grind and have been heat treated to HRC 62-64. The scrapers may be resharpened with a diamond hone or light careful grinding. Since all Hollow-Pro™ Tools have a built in negative angle at the tip, when the M4 scrapers are inserted the result is a clean, less aggressive, final finish cut. Mike recommends using the scraper for your last few cuts, when you are close to your final wall thickness."

http://www.mikejackofsky.com/Tools.html

[Fred Belknap]

Reed I use a swan neck tool in a Monster articulating system and use the round cutter that came with a Sorby swan neck tool, the one about the size of a quarter. I sharpen it the same as my scrapers. It will do a respectable job of getting the inside cleaned up. I doubt I can reach over about 8 or 9 inches. It needs to be set exactly on the center. I'm sure there is several ways but that is what works for me. I sand what I can reach.
BTW I have a tool to put the cutter on to sharpen and when one spot gets a little dull just loosen the screw and turn a few degrees.

[robert baccus]

When asked why I was sanding with 60 grit I replied that I was out of 40 griit. When all else fails 2 quick puffs of rattlecan flat black saves the day.

[Kathy Marshall]

Glad to be the cause of something Reed :eek:.
I use a Jamieson captured system for my hollow forms and at the Desert Woodturning Roundup in February, I picked up a teardrop cutter from Monster tools. It fit right into my Jamieson bar and works very well to smooth the inside. I'm not able to reach the shoulder area on wide squat forms, but it's great on the sides and bottom. Except for cleaning up the very bottom, I use it just slightly above center, and take very light cuts and it hasn't been grabby at all. Before I got the teardrop cutter, I just used the 3/16 cutter, taking very light cuts and just try to move slow and steady, some woods just worked better than others.
If you're using hand tools, then I'm not any help, except for ornaments and minis, I gave up on hand hollowing when I got my captured system.

[Eric Gourieux]

Reed,
I've tried the concave carbide cutters (i.e.: Hunter), Sorby round scrapers, teardrop scrapers, and I always go back to my Hollow-Pro scraper. It is smaller that the Sorby (approx 1/2 " diameter) and works quite well. I've also set up a sanding jig for my articulated hollower when I want a better finish.

[Peter Blair]

Hey Eric. Any chance you would share your sanding set up for your articulated hollower?

[Glen Blanchard]

Hey Eric. Any chance you would share your sanding set up for your articulated hollower?

I'd like to hear it as well. I have been using a small piece of sandpaper wrapped around some rubber-like material on the end of a pair of curved hemostats with a good amount of success, but I am always open to new techniques.

[Wally Dickerman]

I've been using a Dennis Stewart tool since the 80's. Many hundreds of HF's. Dennis Stewart used to put out a tantung steel teardrop scraper. Since the tantung scrapers are no longer available I've had to settle for HSS. Reed, the secret to using a teardrop scraper is to angle it down, giving a shearing NR effect. I get few if any catches. The armbrace tool allows you to do that.

I now use a Monster articulated tool for some of my hollowing, whiich means that I can't angle the scraper down...so, I always do the final cuts with my Stewart tool. I feel very comfortable with that tool after all these years.

[John Beaver]

I suggest rolling the cutter over so it's sheer scraping. You can do this with a tear drop or some of the new carbide tools like Hunter or JT Turning tools.

[Faust M. Ruggiero]

I do exactly what Wally described with the same tools. I cannot say "hundreds of hollow forms" but I have time to catch up to Wally if my luck holds up. I own the Dennis Stewart tool but my tear drop scraper needed replacement so I began making my own from used planer blades. I cut them off with an air grinder and shape and sharpen them with my bench grinder and your adjustable tool rest. I make various shapes and try them out. Since blades are too hard to drill a hole, I usually grind a slot.
faust

[Reed Gray]

Well, thanks for all the tips. I do use the McNaughton, hand held for roughing, and since I have a laser system for my coring tools, it works fine for getting close. I am guessing that it is as much "10,000 more times" as anything else. Right now I am working with some 'too soft' big leaf maple, which is almost impossible to cut cleanly. My preference would be for a tear drop scraper at a shear angle so you are not just scraping but cutting, and at the 45 or so degree angle, you cover a wider path. I do have a Monster system that I use for the final cuts, and I do like it, but wish it was a bit more hefty. Only finish cuts out past about 6 inches. I also have a bigger captured system that was made for me, and I need to get it raised 2 1/2 inches for my Robust as the original went on my old PM. Getting that dead center spot in the bottom is a pain. I do remember the Ellsworth tip about up/down and side to side feeling with the cutting tip, but again for the dead center, a straight on scraper tip doesn't work too well. The concave cup type carbide tipped cutters can take a cut from dead center as long as they are at a shear angle.

Wally, I love tantung. I called up AG Wesson, who makes it down in Florida to get some more. I am going to make some of the old 'Big Ugly' scrapers, but more my style, 3/4 and 1 inch wide scrapers rather than the ones on the 3/4 inch bar stock. I tried to convince then that their product could be used a lot in the woodturning world, but they weren't too interested. The worry is since it is a cast metal, there can be voids. This is why you put a 1 inch piece on 7/8 inch wide stock. For those of you who don't know, it keeps an edge as fine as anything out there, it can be sharpened on standard grinding wheels, and it is almost as durable as carbide. I do have some 3/8 inch wide strips coming for retipping my McNaughton tools.

http://cutting-tools.vrwesson.com/

robo hippy

[robert baccus]

Like Wally and Reed my last tantung is verysmall and hoarded. On my homemade captured system I have a Jamison 1/2" bit holder that is twisted 15 deg? and when the holder is rotated slightly it makes a true shear scraper with a teardrop. Sharpened on a power 1200 diamond disc it really cuts clean. Soft, dry crappy woods can always win somedays. And then there's 60 grit.

[Nate Davey]

I'm really lazy, I got a bunch of broken tempered glass, put it inside the form and let the lathe run overnight (think of a rock tumbler). You have to keep the speed low enough so that centrifugal force doesn't hold the glass is one spot. I'm thinking about getting an old rotisserie motor, welding a 1 1/2 x8 bolt on it, put it on a board I can change the angle on and screwing it to my work bench so I'm not tying up the lathe.

[Scott Hackler]

Reed, I have discovered for me, the method that works the best is to rough out the inside like usual, being as careful as possible to maintain a consistent thickness....then a final push cut, by feel. For what ever reason a final push cut (or two) simulates a non-stop gouge cut and with no start-stop points and the inside walls are generally ridge free. Now I will take a teardrop or Sorby round bit scraper/hollower tool for some final pull cuts at an angle. That's usually as good as I get it. I don't even like sanding inside the forms. Mostly because I try to keep the hole under 3/4" and it's just too difficult and time consuming.

[Eric Gourieux]

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Glen and Peter,

These are the tools I use to sand the inside of hollow forms (when I sand them).

I use the tools in the first pic to sand smaller forms. The two on the left are from Vince (Vinceswoodnwonders), and the one on the right is a shop made ball with velcro on a steel rod. I usually hold this one in my had to sand, resting the rod on my tool rest and angle the ball downward into the hollow form.

In the second pic is a larger 2 1/2" disc holder from Vince. It's an old one that I boogered up and re-glued. It is mounted on a shop-made hollowing tool with a Sorby tip holder. I ground one side of the stem flat to fit into the Sorby holder. I could also mount this on one of the Sorby tools, I suppose.

Reed,
In the third pic is the sander as well as the scraper tip with the Hollow-Pro tool.