Thread: hollow form blow out!

it is one of the most common areas for going through,

It has the sound of beign thicker than it acually is.

It is the old saying measure twice cut once.

Just looking at the photo it has only come out on one patch looks to me you may have a bit of run out ( wobble ) as well as what Jim just said take it slower stop and measure often

Originally Posted by Jim Carroll

it is one of the most common areas for going through,

It has the sound of beign thicker than it acually is.

It is the old saying measure twice cut once.

It's also the area that is easiest to hit and take heavier, controllable cuts. What are you measuring with Smiife???

Bore a hole in this one, put a contrasting tapered plug in it, and carry on.

Nice piece, nice figure, don't give up on it.



You could make or buy a laser guide. In the US one can buy a laser pointer for $5 - $10. Make a bracket to point at the end of your hollowing tool.

Expensive laser guided hollowing tools:

http://www.onewayeuropa.com/hollowing/

https://www.google.com/search?q=lase...w&ved=0CDkQsAQ

It does look like one partial cut of the tool with some run out, did you have a catch? How fast was the rpm?

Smite,

really wish I hAdnt seen this post, I've got a very similar one on my lathe which pushing my skills a bit too far ! Am terrified of blowing it up !! LOL.

i will be making a laser guide fitting soon for my tools, you can get a cheap laser pointer from Jaycar and Officeworks - fwiw.

Regards,
Cam

Smiife,

The blank may have shrunk a bit in that area in the week it was off the lathe, or it may have shrunk more on one side and bent the piece over,making the opposite side thinner when you hollowed. The spigot may have shrunk more on one side making the piece go off center.

Or any or all of the above.

I have had "dry" partially finished pieces move all over the place when left in the lathe overnight. The more interesting the figure, the more they tend to move.

Not always possible but try and turn the whole thing in one day. Like others have said measure frequently and not just in the same spot

I totally agree with Paul39 timber movement most likely way this happened with the time delay from start to finish. If you need to do in stages only rough out and leave plenty of meat to then finish the remaining cuts all at the one time.
Regards Rod.

Hi guys,
In a general reply to everyone,
as to movement i bought this blank quite a long time ago
as you can see it was waxed on all sides, and i thought it
was dry.
time is always a problem for me and i don, t always get
to finish a project in one session, so is it best to leave a project
on the lathe or take off and try get it centred again?

Laser pointer ! might have to look into that one!

Speed and measuring?? Not too sure on either
maybe 1200 /1500 rpm,,, and no I did not measure
with anything..but i will be next time............
No catch...i used my hollower

Thanks again for your comments and advice
much appreciated

Smiife,

My jaundiced opinion of waxed blanks is the seller hopes they won't split until they are sold.

I assume that anything I turn, mostly bowls, is going to move if left overnight, a week, or a month. If I'm going to be back to a bowl within a week, I leave it on the lathe. If the timber is fresh cut, it may rust the chuck, so I take those off.

I got busy with my smaller lathe and left a roughed out bowl of semi dry palm trunk on the big lathe for over 6 months. It twisted all over the place. I had left plenty of thickness so it will be OK.

The "dry" blanks I rough turn leaving the thickness about 5 to 10 % of the diameter, leave it over night and if not too warped take some more off and set it aside for a week or more, then finish.

The found-on-ground or fresh cut pieces I rough out with a thickness of 10 to 20% of the diameter and boil, or soak in dish washing liquid and water for two weeks, or not treat. Then I wrap in several layers of newspaper and let dry for 6 months or longer. They move all over the place and become oval shaped. Then I treat as above for "dry" blanks.

I assume that all timber moves when roughed out, some more than others.

Straight grained kiln dried cherry, maple, or walnut moves the least. Straight grained timber is the least interesting to me. Crotches, stumps, and burls are the most interesting to me and the least stable.

A steady rest could cure a lot of those ills.

Cheers,
Joe

Hi Smiife and all,

Movement is not only from moisture content perfectly dry timber can move considerably simply by the process of removing material from the piece and the resulting release of stresses in the timber can cause serious deflection in the circumference and vertical plane. (as for speed $13.00 digital taco is pretty simple)
Regards Rod.

Originally Posted by sure9

Smiife,tMy jaundiced opinion of waxed blanks is the seller hopes they won't split until they are sold.

I assume that anything I turn, mostly bowls, is going to move if left overnight, a week, or a month. If I'm going to be back to a bowl within a week, I leave it on the lathe. If the timber is fresh cut, it may rust the chuck, so I take those off.

I got busy with my smaller lathe and left a roughed out bowl of semi dry palm trunk on the big lathe for over 6 months. It twisted all over the place. I had left plenty of thickness so it will be OK.

The "dry" blanks I rough turn leaving the thickness about 5 to 10 % of the diameter, leave it over night and if not too warped take some more off and set it aside for a week or more, then finish.

The found-on-ground or fresh cut pieces I rough out with a thickness of 10 to 20% of the diameter and boil, or soak in dish washing liquid and water for two weeks, or not treat. Then I wrap in several layers of newspaper and let dry for 6 months or longer. They move all over the place and become oval shaped. Then I treat as above for "dry" blanks.

I assume that all timber moves when roughed out, some more than others.

Straight grained kiln dried cherry, maple, or walnut moves the least. Straight grained timber is the least interesting to me. Crotches, stumps, and burls are the most interesting to me and the least stable.

Hi paul
Thanks for your thoughts, very much appreciated

Originally Posted by joe greiner

A steady rest could cure a lot of those ills.

Cheers,
Joe

Hi joe,
Not too sure where you are going with that ?

Originally Posted by Rod Gilbert

Hi Smiife and all,

Movement is not only from moisture content perfectly dry timber can move considerably simply by the process of removing material from the piece and the resulting release of stresses in the timber can cause serious deflection in the circumference and vertical plane. (as for speed $13.00 digital taco is pretty simple)
Regards Rod.

Hi rod,
I think that is what has happened,
as for the speed I just turn It up to what i think is safe!