Help Building a Straight Hollowing Tool

[Brian Kent]

I have pulled together bits and pieces of information, materials and measurements for a home-made straight Hollowing tool. This is not for small mouth hollow forms. It is specifically for reaching down 7" into the straight sides of mugs on a Delta Midi Lathe.

I have not found start to finish instructions, so this thread is to check out materials, measurements and process.

5/8" x 36" steel rod (zinc plated just because that was what was available).

1/4" x 1/4" x 2.5" M2 HSS tool bits from Enco. I can drill into the end of the rod on the lathe or drill press and super-glue the tool bit into the hole. Second tool will have an angled flat ground into the end and drilled in the drill press. I have no idea what angle this should be.

Measurements by guesswork:
About 8" of steel sticking out of the handle, 4" into the handle and an 18 to 24" oak handle with copper collar.

I welcome your ideas and corrections.

[Fred Belknap]

Brian I never made any tools but IMO you should mount the cutter with a set screw so that you can take it out and sharpen it. I would go with 3/16" cutter, just what I use in my hollower. I have the 1/4" cutter but don't use it much. I'm sure the set up you propose with the handle would be good.

[Glenn Barber]

Brian- Here you go, this should help you. Oland tool! http://aroundthewoods.com/oland.shtml

http://www.sawmillcreek.org/showthread.php?130700-Making-an-Oland-tool

and finally for on down the road *woodturnersresource.com/extras/projects/oland/index.html*

Good reading and good luck!

Glenn

[Hayes Rutherford]

Brian, drill at 45 deg. for your angled tool, it should work fine.

[Curt Fuller]

About the only thing I would do different would be to make the tool a little longer. 8" outside the handle isn't going to give you much to play with on a 7" deep mug. I'd go 10 or 12 inches outside the handle myself. Once you make the straight tool and the 45 degree tool, you'll probably find a need for a similar tool that will hold a tear drop or round scraper. Same basic idea but grind or cut a flat spot on the end of the rod, drill and tap a screw hole to hold the scraper.

[Brian Kent]

Fred, Glenn, Hayes and Curt - all points well taken. I placed an order for 3/16 and 1/4" cutters. Sure beats the price of ready made store bought tools.

[Aric Krueger]

I would recommend a longer handle for going in 7". A general rule of thumb for safety is that the tool handle should be at least five times the maximum distance you intend to reach beyond the tool rest. This gives you the leverage required for tool control. Therefore, a 35" handle would be required for reaching 7" beyond the tool rest in the absence of a captive system. (This information is printed near the front of every Woodturners Catalog from Craft Supplies USA on a page titled "Woodturning Safety 101"). A new replacement shovel handle made of ash from the hardware store would be ideal (and leave enough extra for some other tool handle; perhaps a 3 point tool if you don't already have one.) If using your own wood, I'd recommend a rived piece (to avoid breakage along the grain in use) of clear wood with no knots or defect.

I made a tool for hogging out end grain material up to 5" deep. It works easily and quickly to 4" deep, but from 4" to 5" deep, you need to concentrate, and you can really tell you need the leverage to maintain control. It has a 25" handle and 8" bar/cutter for a total length of 33".

Also remember to keep your tool over the the tool rest center post as much as possible. Going that far out over the tool rest is applying a lot of force to the rest. I saw a turner snap off a wing of his tool rest while hollowing to about 6" once. It sounded like a 12 gauge shotgun and left a lasting impression on me.

...just my 2 cents for your consideration. :) Good luck and I'll be interested to see what you come up with. :D

[Thom Sturgill]

Along the lines of Aric's comments there are also issues of how small diameter the bar should be for a given reach or overhang. For 5/8 bar 7" might be pushing the limit, If you went to 3/4" bar 36" long I would just put the cutters in opposite ends and grip the bare bar. Ellsworth teaches about a 36" handle for a 9/16 x 12" bar (drill rod not soft steel) Hold it with the back hand held at the end of the handle with the forearm approximately verticle and the upper arm horizontal. This actually takes off a lot of strain. BTW his bars with two bits are about $40 each for the large and less than $30 for the smaller 7"x3/8" bars.

[Brian Kent]

Oops. I should have checked Sawmill Creek before cutting that piece of oak from 36" to 24". :rolleyes: Looks like I will be making a nice Padauk and/or shovel handle! I am sure I can find another use for a 24" oak handle.

I really appreciate NOT learning this stuff from experience. Thank you for all of your wisdom and experience, everybody.

By the way, I saw one of those handle / arm brace combinations for hollow forms. I have the Delta Midi, but it just seems that with a bigger lathe you could just twist your arm OFF.:eek:

Good word about using the center of the rest.
I will also keep my eyes open for 3/4" steel rod. Home Depot just had through 5/8".

This all started with - Hey dad, can you make us some 7" mugs for Renaissance Fair? Sure, no prob.

[Thom Sturgill]

BTW, have you considered making a stave mug?

Cut wedge shaped pieces that would fit together to make the rough outside shape. Turn it just enough to smooth the sides. I would make a pair of jamb chucks to allow for mounting between centers to round the outside. Glue the top (smaller end) on on to allow mounting it in a chuck to turn the inside and create the notch for the bottom. Wrap it in duct tape or plastic wrap to keep it together while hollowing. One smoothed and the bottom notch is cut assemble and optionally glue (barrels are made similarly and not glued)
Use a pair of straps to re-enforce it and hold the handle. Rings could be hammered down to fit tightly into notches on the outside.

While this is a complex project it is period typical and prevents having to do much deep hollowing.

[Brian Kent]

Thom, that is what I have going right now. I did it with my 4/4 oak instead of finding a piece thick enough for a whole mug.

I have an end piece glued on for the sake of turning the insides, but I don't know yet whether to use an end cap or a plug. They will be sealed with a poly finish but will also be on a shelf all but a couple of days each year.

[Thom Sturgill]

I would try to taper the outside some. It looks like you have enough thickness to do that. From what i understand, the 'secret' to barrels is that the wood swells and helps seal - they are never glued. If you taper the outside and just touch the inside enough to round it, I think those will work fine, and that could be done with a scraper. No need to round all the way to the bottom or to flare it out. Sandpaper on a large dowel might be enough to round the interior.

Since they look to be glued up, I would cut a rabbit on the inside bottom and turn a stepped plug that sits against the inner wall and the rabbit wall. At that diameter, I would not worry about wood movement too much, but if you are, cut it slightly undersized and set it in place with either epoxy or silicone sealer.

Since I have kids that do the Ren fair in costume every year (and have been know to go myself) I may just have to make a few of those myself...

[Brian Kent]

Here is a link for he mug that they saw and asked me about, so I am using roughly the same dimensions, but with staved construction:

http://www.etsy.com/listing/97678288/wooden-tankard-beer-mug-or-stein-maple

[Thom Sturgill]

OK, this is what I was thinking
http://www.umsos.org/1aMaryRose-wooden_tankard5.JPG

[Brian Kent]

I am glad you showed me the picture. I was thinking you meant small at the botom and large at the top. I love the lid. You just made more work for me :).

[Wally Dickerman]

Brian, what you are asking about is commonly called a boring bar. My first hollowing tool was a boring bar I made perhaps 30 years ago. Hollowing tools were not available in those days so if you wanted to turn HF's you made your own.

You have received some good advice and some that from personal experience I don't agree with. For hollowing up to 7 inches your 5/8 iunch bar is okay. I suggest a 3/16th in. cutter. You'll need about 10 or 12 inches of metal bar showing and no more than a 20 inch handle. The key is in how you handle the tool. Your Delta midi has a short bed which allows you to stand at the end of the lathe facing the turning. IMO, that's the proper and safe way to hollow when using a hand held tool. (A long and heavy boring bar can be used as a captive tool with a setup like Jamieson's) To properly control the tool, the handle should be tucked under your forearm and against you body. You can actually feel that increase in control. You move the tool by moving your body. Anything but a very large catch will be kept under control. My theory is that most large catches are a result of losing control of the tool in a small catch. Happens so fast you don't realize that.

Cut at or a little above center. cutting below center will invite a catch. Set the rest so that the tool is level or pointing a little bit at a downward angle. Grind the cutter so that there is some cutting edge on the right side.

As has been said, keep the tool over the tool rest post as much as possible. That's especially true with the 5/8 in. post used on most small lathes. A mistake in design IMO. As you get deep into the vessel make your cuts lighter. Less chance for a bad catch. The more tool that hangs off the rest the stronger the leverage. Start your hollowing by boring a hole down the center. I use a 3/8 hand-held drill. Cut from center out. Measure frequently. It's easy to remove too much wood in spots, making the walls too thin. Be aware that in deeper HF's the faceplate is the most secure holding there is.

You can epoxy the cutting bit into the bored hole. Heat it to remove it for replacing it.

I bored a hole in the end of the handle and poured some lead shot in, followed by a wood plug. I've done this with several heavy duty tools for better balance. I used to reload shotshells for my skeet shooting so I have a good supply of #9 shot.

When I give beginners classes in HF's I show the students how to make the same boring bar. Costs no more than $20. I have several modern hollowing tools but I still use my boring bar for part of every one of my HF's. (Except the very small ones)

[Brian Kent]

Thank you Wally. Sounds like I have what I need for my first two boring bars. I can follow most of your advice. My Delta lathe has the extension and is bolted to a turning table. (see picture) I had thought about cutting into the table a few more inches to snug up as close as possible to the bed. I can still use the arm-tuck for straight boring but need to extend away from my body for undercut rims.

Right now I am also doing long turnings for chair legs, but I could remove the extension and cut enough of the table away to stand behind it (of course with more bracing underneath to compensate.) This is especially if I get into something like hollow forms.

I really appreciate the teaching about the center of the tool rest and the position of the cutter above center. When I sharpen the cutter is that about a 70° angle like a scraper?

I have been drilling out the center with a drill chuck on the lathe and either a 3/8" brad point or a wider forstner. That also gives me a careful way to measure depth if I use a recess for the chuck. On my current project I will just use a glued on tenon screwed to a faceplate.

I guess it is time for me to get the right caliper so I can measure the curved wall thickness. I just have the straight divider-type.

I'll use the epoxy.

I don't have any shot handy, but I was saving my pennies - literally and I can put about 4-1/2 ounces of pennies (1 roll) in a 3/4" hole.

Thank you for all of the good words. This is great - Wally and everybody.

Brian

[Brian Kent]

Package came from Enco that includes the 3/16" cutting tools, the right size drill bits and a center punch. I also found a 3/4" steel rod at Lowes, and tomorrow is my day off. Woohoo!

[Joe Kaufman]

I have been using the Harbor Freight Pry Bars for making tool bars. There is sufficient carbon and heat treat so they will flex much less than plain low carbon steel. The corners are already rounded and the plastic handles are useable. Don't try to drill or tap the bar with carbon steel tools. Use Ground HHS taps as carbon steel taps will most likely break off in the bar. As others have stated, metal lathe M2 HHS bits work great for the cutting portion of the tool.

I have a Midi lathe so the longest I have made is 20". The tool bits can also be installed at an angle to the bar for hollowing applications. I use a vice grip on the shaft to counteract the torque.
Joe

[Brian Kent]

The first tool - the straight boring bar - is done.

It didn't cost much but I added to its inherent value by putting some really money into the tool. Most of a roll of pennies.
But when I sanded the end I was reminded that pennies are mostly made of zinc now.
That's why I have trust issues. (I really don't have trust issus, it just seemed like a good thing to say next).

[Brian Kent]

I tried out the boring bar. It works, and I have several observations.

1) I am glad I used the 3/4" thick bar and not the 5/8".
2) I am glad I used the 3/16" cutter and not the 1/4".
3) I only went 5" into the oak mug (end grain).
4) I may have been smoother my first time surfing or driving a stick shift than I was today.
5) I finally got a little rhythm going when I went so slowly that each pass felt like the exact same pass I had just made.
6) I am officially and deeply impressed with people who make hollow forms.
7) There is something like an oak mug sitting on my lathe.

Thank you Wally and all.

Brian