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Tiger
29th May 2006, 12:26 PM
Dear all,

Having a few hours to myself on the weekend, I decided to turn some eggs and some fruit. Went ok except I keep getting concentric ring marks at the ends of the pieces. I've noticed display pieces don't have these. I wanted to know how do they come about and how do you get rid of them?

Also, I used jam chucks to finish the ends. One piece was very stubborn and I couldn't get the piece out. Tried hitting the chuck with heavy objects but still didn't release, how does one persuade a stubborn piece out of a tight fit? Did a search on jam chucks and came back with no matches. Anyone have a good reference for jam chucks?

On one occasion while turning, couldn't get the screw chuck out of the piece, obviously the pilot-hole was too small, again how does one get the screw-chuck out with out too much damage?

Thanks in advance for any suggestions.

arose62
29th May 2006, 01:39 PM
"I keep getting concentric ring marks at the ends of the pieces."

I think more info, or a picture, would be needed to resolve this. Are you talking about fine grooves left from the turning tools, or from sanding, or after you apply the finish? (Holding the cloth in place when finishing can leave rings from the weave of the cloth)

Each has a different cause, and correspondingly different fix.
It could also be the wood, if you are using a piece with the heart of the wood running through the axis of the piece.

"how does one persuade a stubborn piece out of a tight fit?"

Make a hole in the centre of the base of the jam chuck, so you can push the piece out.
Cut slots around the rim of the jam chuck, and use a hose clamp to tighten it onto the piece - loosen the hose clamp to remove.

"how does one get the screw-chuck out with out too much damage?"

The instructions for mine clearly state to lubricate the screw before mounting the workpiece on it - did you do that?

Cheers,
Andrew

Jeff
29th May 2006, 02:19 PM
I have a suspicion. I bet you had a tough time getting one of the eggs out of the jam chuck, then started make them fit a little looser so you could get them out easier. Am I on the right track here? A loose fit in the chuck is one (there are potentially many) reason you could be getting the circles. I have a suggestion. Always go for as tight a fit as possiple in the jam chuck. But, oh no, how to get out the egg without damage? Hah. Drill a small hole into the rear of the chuck so you can put a shot of air from the compressor into the chuck, behind the egg, and it will pop right out...have your hand ready to catch it. I've never had this fail to work. Now, if you start turning pieces that don't have a solid back inside the jam chuck, well, duh, it won't work. Don't have an air compressor? How about a bicycle tire pump? A basketball pump? A breast pump? Oh, sorry, that one won't work! If one of your sweet little eggs is a little loose in it's nest (jam chuck) try putting a bit of tissue paper around it when you stuff it into the chuck, and add a drop or two of water to make the paper swell up. As far as the circles are concerned, it is impossible to know without further info...tools...technique..sharpness. Let us know at what stage the circles appear and then we may be able to figure it out....it could be the infamous alien egg ring circles....

Tiger
29th May 2006, 02:20 PM
Hi Andrew,

Thanks for your reply. Pretty sure that the rings are caused from the turning tools. It seems that no matter how light my touch, they're still there.

Funnily enough, it occurred to me that I should put a hole in the base of the jam chuck but I didn't as striking the other end of the piece through the jam chuck would have dented and therefore ruined the piece.

I also thought about the lubrication of the screw chuck after I couldn't get if off:( . I didn't get any instructions with mine.

Jeff
29th May 2006, 02:31 PM
If you're getting circles from your tools, what tools are you using? If it's a skew you may have an dimple on the cutting edge. Get out the magnifying glass and look at it real close, resharpen and see what happens.

If a gouge, it's how you're using it, or the wrong size for that particular cut. Is it on one end of the egg or both?

Also, what position is your tool rest in? It should be running across the ways to some degree. If you've got it parrallel to the lathe, that will give you trouble too.

If you can figure out eggsactly when it happens we can better help you out of your jam!!:cool: :rolleyes: :rolleyes:

CameronPotter
29th May 2006, 02:36 PM
If it is from your turning tools, then try using a high grade abrasive (80 grit) and sand the egg. It shouldn't take long to get rid of tool marks, THEN if you still gets circels later on, it is soemthing else. I suspect it is the finish.

Cam

Tiger
29th May 2006, 02:52 PM
Hi Jeff and Cam,

Jeff, I have tried to use the skew exclusively on this project to hone my skew skills. If there is a dimple on the skew, then it's pretty small. As for the breast pump, can you show me yours :D . You'll also have to show me how you use it, maybe a picture or two?

Cam, wanted to get the best possible finish off the tool, so reluctant to use 80 grit, but that would probably work as the lines are thin but annoying.

Jeff
29th May 2006, 03:05 PM
I'd be glad to show you how to use a breast pump if you provide your own sweet lass.:p :p :p :p

If you're certain the skew is smooth, then perhaps it is the technique you need to look at. Try to set your toolrest in a position that allows you a longer sweeping motion across the cut area at the end of the egg. If you have to start and stop your cuts it can often leave little marks. I don't want to get into these finer points because it can get a little dicey without seeing what is going on. If you haven't tried it already use a round nose skew and see how that goes. Also, get the speed up pretty high. And, of course it could just be the wood itself, for all I know you're using plywood:D :D :D !

CameronPotter
29th May 2006, 03:16 PM
Tiger, what I meant was try sanding with 80 grit, see how you go. If you still get the rings, then it is something else, if not, then you know that it is definitely a tool problem - which unfortunately probably means just more practice.

Cam

Tiger
29th May 2006, 03:19 PM
I'd be glad to show you how to use a breast pump if you provide your own sweet lass.:p :p :p :p



Hmmm, my wife's not really into woodturning so it might be difficult. I would have to tell her that something very important (rather than an errant jam chuck) is at the heart of all this "research";) .

By the way, the wood I'm using is pine, it's not great but is readily available.

TTIT
29th May 2006, 11:24 PM
Impeccable timing Tiger! Last week I realised I couldn't keep finished pieces from every type of wood I collect - the house just ain't big enough - so I decided to start an egg collection. Also needed some (a lot:o) of skew practice so off I went. Tried hand finishing the parted off end - yuk! :eek:Set up the chuck on the left in Pic 2 which worked but was a PITA to centre and awkward and slow (a bit like it's maker). After about egg no.8, the grandkids turned up and 4 eggs went AWOL. They loved em' so I figured I had better get used to making these:). Rough counting about 20 more wood types to go, I decided there had to be a better way:confused:. Went through the junk pile and found half a 50mm PVC joiner left from another chuck project. Cut a bit of a dovetail on the inside edge so it wouldn't fly off the chuck, turned up the wooden inserts from scrap and Bob's your uncle. A bit of tape inside the ring to avoids marking the egg on soft timbers. Almost self centering, quick and easy to make and use.:D:D:D
PS: Can't help with the fruit (yet!)

Gil Jones
30th May 2006, 04:09 AM
TTIT, that 2" PVC egg chuck is great!!

CameronPotter
30th May 2006, 10:22 AM
I agree with Gil.

Great idea mate.

Cam

hughie
30th May 2006, 11:42 AM
TTIT

Damn fine piece of lateral thinking. I am gonna pinch that idea :D
hughie

Tiger
30th May 2006, 02:26 PM
TTIT, great solution! It has given me some eggsciting:o ideas about how to chuck other objects. One could buy various sizes of PVC as it's readily available and make a number of different chucks out of it.

On the matter of wooden jam chucks, I've never had as much trouble with them as I've had with eggs and fruit, I figure it must be because of the convex nature of the objects that I'm turning. I find that unless you hit them pretty hard into the jam chuck, they won't hold (except for light sanding), then they don't release easily. With boxes as they are straighter there is more surface area in touch with the jam chuck, therefore not as hard to release. For those that use jam chucks a lot, what you think? Is there much you can do to make release on them easier when you design the jam chuck? All this makes TTIT's idea more meritorious.

Sprog
30th May 2006, 06:00 PM
Dear all,

I decided to turn some eggs and some fruit. Went OK except I keep getting concentric ring marks at the ends of the pieces. I wanted to know how do they come about and how do you get rid of them?

You can get this if you are rubbing the bevel with too much pressure, causes slight crushing of the fibres.