PDA

View Full Version : Don't you hate it when...



GoGuppy
11th November 2009, 09:23 PM
After working on the turning of the outside of a cedar bowl for the past 4 or 6 weeks on and off (more off than on :B) and being just happy with the finish achieved (see second photo), I was ready to start hollowing (still a skill I am attempting to aquire...).:rolleyes:

Rechucked the bowl and made the first cut with a freshly sharpened gouge..a light snap...and there lay the bowl on the bed (see firstphoto). Dove-tail spigot still nice and tight in the chuck jaws :oo: :( :toobad: :whatonearth:

Any suggestions what may have caused the bowl to snap off like that??:?

China
11th November 2009, 09:37 PM
How long is a peice of string, just one of those things.

GoGuppy
11th November 2009, 09:45 PM
Thanks China, sounds like a goodnuff concise technical explanation to me:2tsup:.

I gues I'll use an internal dovetail for expanding jaws next time I get round to rechucking it again....:D

Sawdust Maker
11th November 2009, 10:00 PM
bugga

munruben
11th November 2009, 10:10 PM
Doh! :doh:

issatree
11th November 2009, 10:26 PM
Hi GoGuppy,
I take it that was Aust Red Cedar ?.
If so it is pretty soft, & maybe you could have made your Spigot a bit bigger.

As it come off, it has most likely been marked on the outside as it hit whatever.

I don't turn bowls these days, but have done in the past, & I would have done it the same way.

Maybe you could Jam it up against the Chuck, bring up the T/Stock & cut a hole (with a parting tool ), so you can expand the ordinary bowl jaws. Just keep the speed down.
Worth a try, personally I don't like soft timbers, but it is horses for courses.
Regards,
issatree.
<input id="gwProxy" type="hidden"><!--Session data--><input onclick="jsCall();" id="jsProxy" type="hidden">

wheelinround
11th November 2009, 10:27 PM
Bummer but its rescue time an easy fix take bit out of chuck after truing it up on the face, remount bowl and true its face up epoxy together. Return the join nice and easy light cuts.

If you had used expanding jaw dovetail you could have had a blown bowl not just a broken base.

Those jaws look like they'd bit anything off!!

Ok now you have it ready to go turn a bit of wood as a chuck to fit the bowl use hot glue gun and secure to it each other then turn the inside of the bowl.

Or return the base so it doesn't have a foot do as above.

Ray

Skew ChiDAMN!!
11th November 2009, 10:39 PM
:whs:

If it's because the timber is generally weak grained, you could've lost a lot more if 'twas mounted in expansion mode.

I suspect that there was just a fault line in the worst possible spot. It happens sometimes. If that's the case, then you should simply be able to reglue the spigot back on and return the outside. (I wouldn't expect it to spin true and it's probably dented anyway.)

thefixer
11th November 2009, 10:44 PM
Correct me if I am wrong, but it looks from the second picture that you got a bit of a grab with the gouge and that has caused the piece to snap off at the tenon. It also appears from that picture that you may have been presenting the gouge at too sharp an angle to the timber. I.E. trying to use the gouge as a scraper rather than a sheer cutter. When hollowing a bowl try presenting the tool to the timber more like a space craft re entering the atmosphere. You need to come in from the side, start the cut and then feed the chisel in and roll it over clockwise cutting above centre as you feed in towards the centre and then once you have passed the transition area from end grain to cross grain roll the tool anticlockwise and work your into the centre and keep the handle of the gouge low as much as you can. This is so much easier to do than it is to explain. I learnt this from practicing on green timber. Now I can hollow successfully and confidently on cross grain or end grain with dry timber.This technique is most useful when reverse chucking a very delicate piece to remove the tenon.

brendan stemp
11th November 2009, 11:16 PM
Remedy: because it is a clean split you could use some PVA glue to glue it back together. If you line the two pieces up properly i.e. the way they were before they parted company then you will barely notice the seam when glue is dry. Place spigot back in chuck if you have taken it out and use the tail stock (without live centre) to apply pressure to top part of bowl.

Cause: Can't be sure but I agree with Skew in that it probably was just a weakness in the timber. And expansion would not be a better way to do this. Especially with a soft timber like cedar.

In the future: one thing you might consider before hollowing out the bowl is drilling a hole to the depth you want to go less perhaps 10mm. The bigger the better. You could use a 25mm forstner bit for instance. This will help you get started with hollowing and it will also let you know that you are close to the point when you need to stop hollowing.

Good luck with it all.

powderpost
11th November 2009, 11:25 PM
I agree with Brendan... Don't fiddle with the joint, just glue it back together and rechuck.
Jim

Texian
12th November 2009, 01:36 AM
Agree with Jim. Glue it back on (PVA glue), with pressure on the joint until the glue cures. Rechuck with pressure from the tailstock for as much of the hollowing as possible.

artme
12th November 2009, 04:25 AM
Bet you said "Oh dear! and bother""":D:D:D:p

Do what Brenda says and glue together, bring tail stock up for support.
Use the gouge as outlined by our friend The Fixer.

Patience and good luck.:2tsup:

Nice looking chunk of timber BTW.

GoGuppy
12th November 2009, 07:31 AM
Thanks guys for all the good feedback, it's very much appreciated.
Refelecting back on it, I think it may have been a combination of a weak fault line and poor tool usage technique. I will definately PVA the pieces back together and am confident this will hold with a bit of support from the tail stock.
With regard to the gouge technique, I actually (try to) use the method outline by thefixer and have had success with this on other trial pieces, but perhaps the tool rest was a smidgeon high and resulted in a slight catch.
Anyway, I am sure I will recover the work piece and end up with a presentable bowl...watch this space.:D
Cheers

GoGuppy
21st November 2009, 12:30 PM
Well guys, I duely glued the snapped off spigot back to the bowl with PVA glue and set it aside for a couple a days to set. I had all intentions of supporting the tail stock end after remounting the bowl, but I thought 'What if I try without?' :- Guess what.. it snapped off again..:oo::(. Yes, I did say something like 'Oh bother...":doh::D Interesting to note that it snapped off not on the glue line but just behind it.:)

Well third time lucky, I thought better listen to what the forum suggested and after turning a new spigot (of a slightly larger diameter) remounted the bowl and provided support from the tail stock. This proved to be the solution as I had no problems at all after this.:U

Cheers

Manuka Jock
21st November 2009, 10:46 PM
Well guys, I duely glued the snapped off spigot back to the bowl with PVA glue and set it aside for a couple a days to set. I had all intentions of supporting the tail stock end after remounting the bowl, but I thought 'What if I try without?' :- Guess what.. it snapped off again..:oo::(. Yes, I did say something like 'Oh bother...":doh::D Interesting to note that it snapped off not on the glue line but just behind it.:)

Well third time lucky, I thought better listen to what the forum suggested and after turning a new spigot (of a slightly larger diameter) remounted the bowl and provided support from the tail stock. This proved to be the solution as I had no problems at all after this.:U

Cheers
Alls' well that ends well eh :2tsup:

artme
22nd November 2009, 07:20 AM
Bet you won't ignore the combined wisdom next time!!!!:D:D:D:p:p:p

Nice result. Beautiful grain>:2tsup::2tsup::2tsup:

How did you find it to sand?

wheelinround
22nd November 2009, 08:34 AM
:2tsup::2tsup:

texx
22nd November 2009, 09:09 AM
i have a theory on why this happens . course i could be wrong :oo:. and it wont be easy to explain without diagrams but , when you are using a chuck in that way on a dove tail spigot setup if you keep cranking the chuck up real tight i rekon the spigot pulls into the chuck because of the dove tail taper , now it can only pull in so far until the bottom of the bowl comes in contact with the jaws from then on any more tightening of the chuck is trying to pull the spigot section off the bowl its self , or pull the spigot in and push the bowl out , probably depends on how much angle is cut on the spigot dove tail , then depending on the grain direction , i think if the grain is parallel to the face of the chuck it will split quite easy.
kind of the chuck jaws are working as a wedge to separate the spigot from the bowl .
what ya rekon good theory or load of rubbish

GoGuppy
22nd November 2009, 01:51 PM
Thanks Guys, and no won't ignore collective advice in future :no::no:.

Hey Texx you might be onto something there.....I can see the theory, but if this was the case wouldn't you hear about this happening all the time on softish kinds of woods?

Artme, sanding was a b*gga, in fact after I posted the above photos I spent a bit more time finishing it (photos are unforgiving :-:-). I turned away the chuck marks on the spigot and had another go at sanding it a bit more and waxing it. But even now, at the areas of end grain. you can with a very gentle stroke of a finger brush the endgrain one way or the other, with a resulting lighter or darker appearance, depending on where the light is shining from. That's OK though, I can live with that..I think.
Cheers

rsser
22nd November 2009, 02:06 PM
If the dovetail angles matched and the jaw face was properly against the bowl bottom the spigot shouldn't have gone anywhere.

Cedar's so soft it doesn't surprise me that you snapped it off. And it's a sod for tear-out.

Onya for persisting.

At casa del Ern it would've hit the wood pile.

texx
22nd November 2009, 02:13 PM
Thanks Guys, and no won't ignore collective advice in future :no::no:.

Hey Texx you might be onto something there.....I can see the theory, but if this was the case wouldn't you hear about this happening all the time on softish kinds of woods?

Artme, sanding was a b*gga, in fact after I posted the above photos I spent a bit more time finishing it (photos are unforgiving :-:-). I turned away the chuck marks on the spigot and had another go at sanding it a bit more and waxing it. But even now, at the areas of end grain. you can with a very gentle stroke of a finger brush the endgrain one way or the other, with a resulting lighter or darker appearance, depending on where the light is shining from. That's OK though, I can live with that..I think.
Cheers
on the sanding thing that is the very reason why when i built my lathe i had it wired for forward and reverse , and for the last few sanding grits i sand with the lathe spinning both directions ( not at the same time of course :U).
it helps when sanding some woods ,helps stop that furry finish that you get when the fibers are all laying one way kinda

GoGuppy
22nd November 2009, 05:12 PM
Yep, I've heared about reversing for sanding and in fact a reversing switch was thrown in when I bought the Leady.

But, I might wait with hooking it up, I've heard Santa may have a variable speed drive somewhere in the bag.....:rolleyes::rolleyes:.

brendan stemp
22nd November 2009, 05:54 PM
Top marks for perseverance .... and workmanship. Well done GoGuppy.

Ozkaban
23rd November 2009, 09:03 AM
Sounds like it was a useful experience all round - you get a nice bowl at the end, and have a couple of learning experiences along the way... Oh, and a couple of people on the forums got to say 'I told you so':D:D

What more could you want from one block of wood :rolleyes:

Cheers,
Dave

rsser
24th November 2009, 09:18 AM
Re reverse sanding, just reverse the direction of the power sanding disc if that's what you're using.

FWIW with fluffy grain I've found that more is often needed. Water, oil, wax or sanding sealer; sometimes one of those as well as hand sanding.

GoGuppy
24th November 2009, 09:25 AM
Re reverse sanding, just reverse the direction of the power sanding disc if that's what you're using.

FWIW with fluffy grain I've found that more is often needed. Water, oil, wax or sanding sealer; sometimes one of those as well as hand sanding.

Yep, agree with this and did all of that...:wink: and as I said it was a b*gga, but am reasonably happy with the end result.:D
Cheers