Hollowing a cross-grain pot

John,

Part of your theory is correct, but you must also consider how far your tool was extended beyond the tool rest. In most situations, the closer you can keep the tool rest the better you are able to control the tool. A longer handle can help because you are increasing your leverage. Others here are more experienced than I and I'm sure you'll get more feedback from them.

Good Luck, JD

Might. Leverage is good, but only when you're trying to use the tool as a lever. Scraping broadside is one such operation. You really have to rely on your rest (fulcrum), and if it's far away what happened to you can happen easily.

Might want to consider edge presentation as the problem. Hollowing along the grain is easily accomplished with tools like hooks or rings, Darrell's Oland or a pointy gouge, as I use. It shears rather than bludgeons, and with the gouge, as I use it, has a bevel to stabilize it and prevent a catch. From what I can see, Darrell lays the side of the tool up against the wood for stabilization as well. The ring or hook tools have a bit less to stabilize them, but with a good rest there's enough there to maintain a catch-proof angle if the mouth will permit the handle enough travel. Any fingernailed gouge will also work, albeit more slowly, since the sweet spot is pretty small to get a good shear.

In message , George writes

I think part of my issue is obviously limited selection of tools. A secondary issue was that with an opening of only 2 inches and a working depth of about 4 inches, I was restricted on my options, and as such no option for my tool rest to be any closer to the working face. It was however as close as comfortable to the work piece.

Part of my thinking on the use of the tool was that with a longer handle you have a greater movement which means in my mind would be easier to sense and thus give a greater ability to react to the movement, where if its a short handle the movement may only be a fraction of that, and therefore less easy to respond quick enough. Another factor to that is that when you have a shorter distance between rest and tool you tend to grip tighter on the tool, than when you have a greater distance which tends to be a relaxed grip.

I think it really comes down to me having to by a bigger selection of tools :)

There will never be enough! But that's a good thing, especially if you have spouse, children and such. Three gifts and some Hallmarks every year, right?

Hello John,

About 15 years ago, when I had fewer tools as you likely do and wanted to do a hollow vessel, I made myself a hollowing tool using a three foot length of 3/4" round steel rod. I drilled a hole in the end of it to accept a 3/16" square machinist cutting tool. It seems like that was about a 1/4" hole. I then filed off an angle space, 45 degrees to the the shaft and drilled another hole that intersected the hole in the end of the shaft. At the intersection of the two holes, I drilled and tapped a hole for a 1/4 inch set screw. This allowed me to put the tool in the end for straight in cutting or at an angle for expanded cutting. I ground the cutter to have a semicircular cutting edge with about a 70 degree bevel. I haven't used this tool in several years, but it worked quite well.

I think this is probably similar to Darrell's Oland tool, but I had never heard of the Oland tool when I made it up. This is probably the leaset expensive solution to your problem. I never did put a handle on the tool, but simply gripped the shaft. One thing that I never thought of at the time was putting a second handle on the tool at right angles to give me more control of the tool when it wanted to rotate when using the cutter in the 45 degree hole. That trick I've learned about since making up that tool.

As others mentioned, there are many fine tools on the market to do hollowing and today, I own many of them. The best are the stabalized boring bars with the laser guidance system to keep one from turning through the side or bottom of the vessel.

However, as George says, with experience, you can do much of the hollowing with a sharp pointed bowl gouges with swept back wings. For less experience people, something as I just described or one of the hollowing tools on the market will serve you better.

Fred Holder

In message , George writes

Fortunately/Unfortunately only wife and dog. Though I can usually get whatever tools I want, I just need to decide which to get first.

And I keep having to turn dog bones ! Even today the checked offcut from the log I hollowed became a dog chew. Well at least its better than her chewing bricks :)

longer, thicker scrapers are always good if you can afford them (I can't)

Type of rest can be as important with a scraper as where it is, IMO.. For stuff like you're doing, I really like a box scraper rest... (Item G in link below)

You get better support and can usually get some of the rest inside the opening that you're working.. As you get more experience with the scraper, you'll also have less catches.. it's actually pretty hard to get one once your technique smooths out..

mac

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As you say to pointing the rest into the hole and laying the tool on it length wise hence having a large surface area of contact would definitely increase stability

Something else I just remembered which is probably a big factor is the height of the rest to centreline of work piece. I was looking into this the other week, and found that the lowest height of standard tool rest is (using metric here) 5mm below centre, with the tool being 7mm thick ( One reason I have been looking at an upgrade to the lathe. But if I make some rests I can drop that height

I must say I only get a handful but they are often spectacular, but if I can reduce the controllable variables maybe I will make none :)

I can remember when hollowing a box with a 2 or 3" opening to a depth of a few inches was challenging.. Then, again, that's when I ran to Harbor Freight and bought a set of cheap forstner bits..

mac

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Cool.. if you lived in my neighborhood, I'd keep ya busy! While you're at it, make some flat-topped rests in like 3", 5" and so on, the sizes that you can't buy...

Yes, and maybe just as important, it gets you used to good angle on the scraper and will minimize catches..

I'm going through the results of doing just that... When I was using the 14" Jet, I bought several rests and most were a an inch too long for use on the Jet, so I shortened them..

Now that I've moved up to the Nova I find that those rests are too short to use on it... ya just never win..lol

I've found that as you get more experienced and more comfortable, and have enough catches, they become much smaller.. and because you've "been there, done that", your reaction is a lot milder, which minimizes damage to the wood, tool and you, and keeps the laundry bill lower..

I really hadn't thought about that until I recently got the Nova and read about the spindle sensing going on in it's brain and that if it detects a catch it stops the motor... I realized that it's been a long time since I had the real "thunk" kind of catch that makes the belt slip... the few I have now are more of a "tap" and are easily corrected..

mac

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Don't jump too fast. Remember, the piece is rotating, and the edge in contact wants to twist the handle, not tip. Not a lot of gain in the box toolrests except in bottoming unless you can extend them inside the turning and up close to the sides.

Percentage play lies in limiting the amount of metal in contact while scraping by using a narrow bit like Darrel or the other makers of hollowing tools, or increasing the amount of metal in contact when cutting, thereby stabilizing on the place you've been to get where you want to go. It's the principle behind "shear scraping," which is cutting without benefit of a guiding bevel. If you use the side of your cutter or buy one of those depth-limiting kinds like the Munro, you're following precept two.

Other thing you may have noticed about the commercial tools is that they get you handle swing by curving the bit holder, yet keep the bit in line with the main handle to minimize leverage and twist.

One principle I learned from the first book I ever read on turning (old bodger name of Frank Pain) was that you can't get a catch if your cut is above the wood. Inside, that means below the center, outside, above. Figure your toolrest height from those principles, and things will go a bit easier.

From what everyone has said, and looking into the tools mentioned and more, I have an impression that the tools that have a 'better result' ( I include safer in that) are essentially a very mechanical construction, almost similar in operation to the tools on a metalworking lathe, albeit quite a different construction. i.e. the user is not really a part of the equation other than for moving the tool.

I have found an interesting design in the poolewood catalogue

if the link doesn't work try and search for 'dave reeks' I think that in the coming months I will be constructing something similar, combined with the ideas mentioned elsewhere in this thread for the toolhead design. The most obvious extension of the design would be to include laser guidance I wonder if anyone here has tried/used a dual laser design for guidance, all I have seen are single lasers. My thought is either one vertical laser which is common and one horizontal both pointed to the tip of the tool edge, or both from above but at 90 degrees to each other Using this method the thickness of the form could be determined by how close the lasers are on the surface

Oooh so many ideas to play with :)

In message , mac davis writes

I think it was the JET 3520 I saw which had the best design, with the hole for the tool rest offset on the banjo, which in theory would allow as long a stem as you like. This is other than the occasion of avoiding the lathe bed, and assuming the top of the banjo is low enough

My usual result it to loosen the turning in the chuck jaws, and the worst, using it as a a projectile across the room. Unfortunately with a minimum speed of 400 I am partly restricted. So tool rest is as close as possible which helps control the missile :)

Wow.. that's (in my mind) a pretty radical tool, especially for what you're doing.. I think if I was going to spend that much money trying to imitate a metal lathe, I'd just use a metal lathe..lol

You might consider a rig like that in the future, John, if you get into hollow forms and such, but what you need right now to do your 4" deep, 2" wide hollowing is more practice with the tools you have... Just a little patience and a learning curve and you could do that hollowing with a bowl gouge.. *g*

Remember that folks have been making cups, pots, vases, etc. for a lot more years than we've had high tech laser guided carbide robotic arms available.. YMWV

Also, since you seem to have metalworking skills, (wish I did), you might want to learn a bit from the master and make one of these:

Since I'm metalworking impaired, I have one of these for hollowing: but I wouldn't use it on something less than maybe 5 or 6 inches deep as it really doesn't work well with shallow stuff..

mac

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I think because of my background, Avionics QA, Production and R&D I have too often seen low cost solutions employed to a problem, only to see a few months later the investment being discarded for a more expensive but reliable/versatile solution. For that reason I often now invest to save :) Another advantage of this approach is one learning curve rather than two or three.

If I can sort my tool rest I think the bowl gouge will work a bit better. At present with the standard minimum rest height and the rest is touching the face of surface being turned, to get the bevel to rub the cutting edge will be almost 1/4 inch above centre. My latest bowl gouge has better swept wings, and have found that it seems to work a lot better, but I need some more practice.

Very true. I think technology has improved some aspects, but also taken some of the skill out of the process. As I do not consider myself to have the skill level to achieve quality results, I can use the technology to fill the gap :) Maybe one day my skill level will rise so that I am pleased with my results without the fancy technology

I have a few nice blanks here which are 12inch + deep which I will play with later in the year, when it gets warmer ) My workshop has recently been up as high at 6 deg C

Well, the termite and my other toy, the Supercut "universal tool" are both supposed to be for end grain but seem to work fine for either orientation.. I'd guess that they're called "end grain" tools because that's a task that most of us find more difficult than cross grain?

I (no longer) feel your pain.. I used to use my shop about 6 months a year when we were in the States.. Right now, at 7pm, it's hovering at 22C with the outside temp at 19C

mac

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Seems to me you got this exactly backwards. Inside below center the catch drives the tool into the wood. Same with outside above. Inside above center a catch drives the tool into air. Same with outside below.

Seems to me you got this exactly backwards. Inside below center the catch drives the tool into the wood. Same with outside above. Inside above center a catch drives the tool into air. Same with outside below.

Nope, Catch comes from raising the nose of the tool into wood or the wood coming down into the nose of the tool. Keeping air over the tool keeps from catching. Puts you at 8:45 inside, 9:15 out as optimum. The bevel on the wood keeps you steady and away from a roll and catch.

Of course you are talking non-cense George. A catch is a un-controlled dig into the wood, be it a spindle or bowl, inside or outside. That means the tool is taken by the turning wood in its turning direction. A tool inside a bowl cutting above centre height will be pushed down into air, end of catch, and a tool cutting below centre, will gat pushed down also, but into the wood, digging into a mayor catch. A tool cutting on the outside of a bowl below centre will be pushed down into the air. above center just the opposite. Maybe you have to draw a picture george, and see what a tool does, when it gets caught on the outside of a turning, it goes down george, it makes an arc george, as the tool rest is the fulcrum, and the tool going down will have the end swing away from the wood. Maybe someone can draw a picture for you george, have a nice day george