although i've never used one, i am familiar with the way a hollowing rig works. however, the other day i stubbled upon somebodies gallery and they had turned a 14 inch vessel with a 1/2 inch opening. just was wondering how this was possible or if anyone knows how this would be done?
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the smallest opening possible on hollow vessels
- Thread starter jcooper
- Start date
I saw Dave Hout turn a vessel on DIY that had a very small opening. He cut the top off, hollowed out the bottom, lined up the grain and glued the top back on, then finished hollowing out the top through a small opening.
Hope this helps!
Hope this helps!
I've seen the same technique written up as well as used by turners. A skill job of cutting and later gluing the piece back in place can be really hard to spot. Otherwise I don't know how you would manage to hollow through a 1/2 opening, especially one with a bit of a neck to it, without leaving pretty thick walls. Hollowing tools made from the same material as Gumby and Pokey? Hmmmmmm?
Seriously though. I suppose you would use as heavy a stock of metal that you could get through the opening and bend it to allow it to reach the walls and shoulder of the vessel, and use a really light touch?
Am curious now, how narrow an opening have you folks hollowed through and what were your experiences?
Dave
Seriously though. I suppose you would use as heavy a stock of metal that you could get through the opening and bend it to allow it to reach the walls and shoulder of the vessel, and use a really light touch?
Am curious now, how narrow an opening have you folks hollowed through and what were your experiences?
Dave
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wdwork
I have seen a few vessels that were hollowed through a hole in the bottom,then a plug of matching wood is glue in the hole.If done well, it can be hard to spot.
I have seen a few vessels that were hollowed through a hole in the bottom,then a plug of matching wood is glue in the hole.If done well, it can be hard to spot.
Smallest opening
When I want to hollow out a piece deeper than about 14" I have to go from the 3/4" bar to a larger one. I have a 1 1/4" bar for more stability ( keep the vibrations down). A 1 1/2" hole will leave very little room for this bar. Keeping in mind you can see the bottom through a 1 1/2" hole. If I have very much of a curve at the top of the piece I need even more room. In an old John Jordan tape he shows how to part off a section of the top to be re-attached later. Now you are limmited to a size opening that can be covered up by the cut off's dia. Once the piece is hollowed and the piece glued back on you can turn the finial shape outside and drill any size hole. If you are careful to match the grain it is very hard to see where the pieces were joined.
Ron 🙂
When I want to hollow out a piece deeper than about 14" I have to go from the 3/4" bar to a larger one. I have a 1 1/4" bar for more stability ( keep the vibrations down). A 1 1/2" hole will leave very little room for this bar. Keeping in mind you can see the bottom through a 1 1/2" hole. If I have very much of a curve at the top of the piece I need even more room. In an old John Jordan tape he shows how to part off a section of the top to be re-attached later. Now you are limmited to a size opening that can be covered up by the cut off's dia. Once the piece is hollowed and the piece glued back on you can turn the finial shape outside and drill any size hole. If you are careful to match the grain it is very hard to see where the pieces were joined.
Ron 🙂
Did the form have a collar? If so that could explain it. You can work through a larger opening and then cover it with a collar.
Ed
Ed
I think the shape of the vessel has a lot to do with how large the opening has to be. I find that if the shape is basically a sphere, (at least at the top of the vessel) hollowing with 1/2" tools may be possible. But the opening has to be at least 5/8" or a bit more. 14" in diameter is a bit of a stretch though. Things start to vibrate too much. If you use light cuts - and lots of them - maybe possible. I think it would take more control than I have. When the design starts to get flat - it gets much tougher. I have done some fairly large vessels (for me) about 15" - 18" diameter using the Stewart tool (3/4" dia.), but I need about a 1" opening to get the tool head inside the vessel.
1/2" openings are pretty much reserved for smaller vessels up to about 8" - 9" dia. in my shop. I used to try to make the opening as small as I could and have found that in looks a 1/2" opening is not that much different that a 1" opening. You just can't get your finger in a 1/2" opening. It seems that it is just more of a challange to make a smaller opening.
Of course there is always the larger opening with a hidden joint. If you put a small groove or a slight bead at the joint - you can get a pretty good match. I have seen some of John Jordans earlier vessels that one had to look hard to find the joint.
Hugh
1/2" openings are pretty much reserved for smaller vessels up to about 8" - 9" dia. in my shop. I used to try to make the opening as small as I could and have found that in looks a 1/2" opening is not that much different that a 1" opening. You just can't get your finger in a 1/2" opening. It seems that it is just more of a challange to make a smaller opening.
Of course there is always the larger opening with a hidden joint. If you put a small groove or a slight bead at the joint - you can get a pretty good match. I have seen some of John Jordans earlier vessels that one had to look hard to find the joint.
Hugh
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Hugh said:
Here's where decorating the bottom with a couple of harmless grooves comes into play. Only it's not really a groove, it's a method of masking the slight grain mismatch between the parted-off and reinstalled plug which hides the comfortable hole you worked through and what you end up with.
It's doubly clever, because most people won't be picking the piece up and turning it over anyway, but will rather be studying the upper areas for a sign of a non-existent join. I don't regularly do built-up pieces, but if I did, you can bet they'd be turned as mating open bowls for final assembly.