help, big bowls, big problems

Allen,
You will probably get other ways to re-mount this, but here's my idea. I would mount my chuck in the headstock and insert a jam chuck of some kind. Another smaller roughed out bowl would work. Place your damaged rough out over the smaller bowl, bring up the tailstock with the point of your dead center on the center point of your recess, put enough pressure on it to hold it and re-sculpt the bottom including a new recess. When finished, loosen the tailstock and cut the small nub under the dead center off with a flexible saw. With regard to your recess, try and make your recess or tennon just slightly larger than the closed diameter of the jaw set you are using. The closer the recess/tennon is to the closed diameter of your jaws the more bearing surface the jaws will have on the piece and the better the jaws will hold. Also, after you make your new recess give the inside edge of the recess a liberal soaking of thin CA glue. It will harden the fibers in the area and help keep the wood from tearing. Try and keep the glue inside the recess because if it runs it can leave 'stain' marks that are hard to sand off. You can use blue painters tape to help control it.
I always use roughing out a bowl as an opportunity to practice some finishing cuts. I notice a lot of tear out in the end grain sapwood. If the wood is truly green, the sapwood should be turnable and not too punky. If the log was down for a while the sapwood deteriorates fast, while walnut heartwood will be workable for years. I suggest you look up some YouTube videos demonstrating shear scraping with the bowl gouge (you can shear scrape with the easy rougher too, but it's more prone to catch because of the small cutter) and use re-sculpting the bottom of this piece for some shear scraping practice. If that's really green sapwood, you should be able to shear scrape it smooth as a baby's buns and it will be less work when you finish the piece.
 
I don't think the blank was really green. Im not sure.

I knew right away I made the mortise a bit larger than usual, its all that sapwood that chipped out and I tried to even it out.
the diamond shaped cutter on the easy tools has always made the mortise cut very simple for me. I cut the mortise so the outside of it is on an angle so the chuck is very secure.(ive made 1/2 down plates and a few bowls and have not a problem of the mortise side cracking off, but Ive never turned fresh wood)

Ive seen the chucks that holds the bowls reversed so you can finish off the bottom, I don't own one of those, like I said, I don't want to dump a ton of money into this all at once.


first, Id have to go buy a fortsner bit large enough, the ones I have don't cut, so much for amazon and its bargains.

if I cut a new mortise, the bowl will lose another 3/8 or so of depth, but I may not have a choice.

before I wrap it up, Im going to rechuck it tomorrow, move the jaws so they are as far away from the chip as possible, and see if I turn at real low speed and very light if I can get a bit more out of the inside, then Ill let it dry for a few weeks and take it from there.

Its weird, its really troubling me, even though its only wood, losing a piece like that bothers me.

Ill try teds suggestion and use one of the scrapers I have to smooth out the outside., Ill try at least.

ok ted, after looking at vaughns thread, (I realized maybe I should just stick to flatwork), I see what you mean about a smaller scrap bowl...oh wait, I don't have any bowls turned to do that!.......its a jam chuck thing, liked the idea using the rubber matting to hold in place........but before I attempt that, Im going to see if I can rechuck it and go slow.
If I can get the jam chuck idea to work for me, I can just make the mortise a bit deeper and rechuck it, would only have to go another 1/8th or so.
 
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Allen,
Sometimes if the bowl isn't too deep, I just put the chuck with the jaws open as wide as possible on the headstock as a jam chuck. Try it, and if the rim of the bowl clears the lathe you're good to go.
 
...ok ted, after looking at vaughns thread, (I realized maybe I should just stick to flatwork), I see what you mean about a smaller scrap bowl...oh wait, I don't have any bowls turned to do that!...

Doesn't have to even be a bowl. It could be a disk of scrap plywood mounted on a faceplate, with the edges rounded over and trued up. Size-wise, it just needs to be a bit smaller than the inside of the bowl at the rim.

With your existing recess, are the jaws on your chuck pretty much closed, or are they opened up quite a bit?
 
Doesn't have to even be a bowl. It could be a disk of scrap plywood mounted on a faceplate, with the edges rounded over and trued up. Size-wise, it just needs to be a bit smaller than the inside of the bowl at the rim.

With your existing recess, are the jaws on your chuck pretty much closed, or are they opened up quite a bit?

Id guess halfway.
 
Well my thanks to you Allen for asking all these questions and Vaughn and Ted thanks for the explanations i learnt a ton. And i have been eyeing that one way center for years since Stu first posted it. Time to pull the trigger. What a clever idea to mount the faceplate with bowl on center. Would never ever have thought that was doable. Thanks guys.

Sent from my SGH-I337M using Tapatalk
 
I think it takes more talent to make the jam chuck, as it has to be exact.

I didn't think it was going to be easy.

That's why I use a "friction" chuck as opposed to a "jam" chuck. No measuring or precision needed. Instead of a perfect fit, I rely on keeping the tailstock in place all through the process of turning away the tenon.
 
What Vaughn said...friction chuck is better. That's really what I was advocating. I just got the terminology mixed up...but the 'chuck' part was right:)
 
From you remarks about the wood not being green the pictures look like punky wood to me (able to pick it with a fingernail). I use shellac thinned down to 1 pt shellac to 2-3 pts dna. It will firm it up a lot but still only penetrates about 1/16-1/8". It dries quickly and you may have to reapply every few cuts. You can also use Minwax wood hardner but it takes a lot longer to dry and may stain the wood. If it is punky I would turn a disc of good wood to just fit the recess and glue it in.
I would turn this off at the end to finish the base and not try to cut it off on the bandsaw or other tool.

I normally use recesses and size as indicated below. It is easy to lay out the diameter with a set of dividers. This allows the best fit when resized after the item has dried. For tenons I do make them about 3/8" larger to allow for warping while drying.
Stuart Batty has three very good videos on chucks/tenons/recesses.
http://vimeo.com/woodturning/videos/sort:alphabetical/format:thumbnail

Like many others I use a friction chuck to finish the base. You can use the chuck jaws themselves but it doesn't take long to turn a few disc to fit your jaws.
Mine are about 3" - 6" diameter and I try to match the diameter to a little over the size of the base. This puts support where you are making the cuts.
 

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thanx for all the advice everyone,

I had zero motivation yesterday and today, the weather absolutely gorgeous, put the top down in the car, went out parked yesterday at the Brooklyn promenade, a walkway across the river overlooking downtown manhattan, took a walk, had lunch...and today, another glorious day, put the top down, went to the local casino, for a quick bit, then went out to lunch again, now sitting here doing nothing but reading.

Hopefully, tomorrow I will resume and get going on the logs.

ted sent me a beautiful chunk of cherry already rounded out ready for the lathe, a large piece, so Im hoping I don't ruin that one and get to work on sometime early next week. Wedding this Saturday, surprise 60th on sunday, and doing the final office installation at my sons home on Monday.
but Im off flatwork as long as I can stall my wife and her new plans for her updated sewing room, all the furniture I made her is getting scratched, she wants a new design.
 
I learned something new today, and Im really ticked off about it.
Having a frustrating time with the bowl, I left it on the lathe and just closed the shop down.
Been 2 days. Went out there today to realign the chuck, got it in for a while until another piece chipped out so I was done, wrapped it up in paper and will get back to it whenever, gotta make a jam chuck eventually to finish it.
But I did notice, the moist shavings from the green wood, totally rusted my lathe bed. I left the shavings on there, never cleaned up, never had this problem before.
Ill have to address that problem tomorrow, I was busy doing the second piece. this chunk had cracked, and it cracked all the way through one side so I had to trim it down, round it out, it was very uneven, so as suggested by Vaughn, used my power planer, got it even enough and face plate mounted, after I got the sides even, I worked on the bottom quite a bit to get it flat as it was very uneven and made the piece unstable.
this one is going much better, a lot smaller, but I didn't have a choice.
you can see after turning the bottom a bit, I still had a very uneven piece, so I kept going until I got the flat section off and now its all nice and bowled shape. Will flip it whenever I get a chance and continue shaping and inside.

I know this is all mickey mouse easy nonsense for the bowl turners here, this stuff is a lot harder than I thought, but even with that, its still loads of fun and enjoyment.

btw, I experimented with my scraper and one inch bowl gauge (harbor freight 3 dollar chisels), after sharpening the 1 inch bowl gouge, it worked great for me, had less catches than my carbide tools. go figure.
 

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Allen,
If you are going to be away from the lathe for any length of time (hours/days) and leave a partially finished piece, it's a good idea to wrap the piece in a plastic bag to keep it from drying out. Maybe not so important with a big chunk like you have now, but its a good habit to get into for everything. I've come back to some pretty warped and cracked bowls before I learned my lesson:( Also, do you have a picture of your 1" bowl gouge? That's awful big for a bowl gouge and I'm concerned you are using a spindle roughing gouge as a bowl gouge, which could be very dangerous.
 
it looks like a spindle roughing gouge, worked great for me, no catches, why so dangerous? I only used on the outside to shape it.
as I read, I see I wont be using it anymore, darned thing worked so well on the outside to get it all even.
 
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it looks like a spindle roughing gouge, worked great for me, no catches, why so dangerous?

Allen the roughing gouge doesn't have a strong connection to the handle. I haven't taken one apart but am told that is something like the tang on a file and can break out of the handle if you get a serious catch. When I started turning I used mine on a lot of out of round bowls with a lot of bang, bang, bang going on. It called a roughing gouge so I thought it was for roughing out bowls. Your bowl is looking good. If I am going to leave a green bowl on the lathe for a while I put a grocery bag over it with a rubber band holding it on. Good luck and keep us posted. I put my rough outs in denatured alcohol over night or longer to help keep them from cracking and reduce the drying time. I still have a few that crack.
 
What Fred said, Allen. The tang on most SRG's is a weak point that can bend or break during a catch or, because they are fairly short, can actually break out of the handle and go flying. This guy talks about it at about 8:45...the rest of the video isn't bad either. https://www.youtube.com/watch?v=4CGkUi_zHVs John Lucas also talks about it at the end (9:30) of this video:
https://www.youtube.com/watch?v=h8YYYYA-6jQ&list=UUZrs6ZBE4MSW-cA72xg8Uhg
I didn't believe it either until I had a colossal catch with that wide blade and nearly threw my arm out.
 
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the tool has been just about retired. I read about why its not used for bowls.
I rarely do spindle work, and when I do, Ive used the carbide tools and found tht they work extremely well.

thanx again for the heads up.
 
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