Help requested - Black Heart Sassafras

[Sebastiaan56]

The piece is on the lathe. The timber has two distinct characteristics, one half is heavy, dense etc, the other a lot more like Pine. The consequence is a shed that shakes and a turning that is perpetually out of round. Im sanding out the tear out, goes very well on the hard stuff, but the soft bit just digs away. Increasing the speed just shakes everything off the shelves and going at 350 is a bit tedious, 800 seems about the best.

I've packed the mushy area with some CA, and I'll see if that helps, anyone have any other ideas?

Sebastiaan

oh yeh, the date on the blank was 23 May 1993.

[Gil Jones]

Sebastiaan,
Kinda difficult to answer your question without a picture to look at. If you have not cut to far in, you could dismount the wood, remount it 90deg with the punky end toward the tailstock, and turn a spigot for your chuck on the hard end. Just a guess without seeing it.
Cheers,

[Sebastiaan56]

Good point Gil,

The blank is about 12" round, 3" deep, mounted on the chuck. The objective is a bowl. Its all roughed out, its finishing it that is a PIA. Im letting the CA dry and will see what happens, Ill get some photos later, chores next,

Sebastiaan

[Skew ChiDAMN!!]

Sounds like it's half sap-/half heart-wood.

Do you have it mounted on a chuck or on a faceplate? If on a largish faceplate, you may be able to bolt counterweights onto the faceplate to effectively balance it out (as far as the vibrations are concerned) and run it a higher RPM.

It's bloody fiddly though and there are definite risks: I've only done it twice that I can think of and have no great wish to do it again...

Still, this is how I've done it: mount a large disk of MDF to the faceplate and the blank to the MDF. I then removed the drive belt, so the heavy side of the blank dropped to the bottom, and used some blue-tack to attach weights (and the mounting bolts) to the top of the disk. I kept doing this, changing weights and positions until the same side didn't always drop to the bottom when I gave it a spin by hand. Once it was balanced to my satisfaction, I removed each weight one at a time, drilled a hole in the MDF and bolted the weight back on. I also drilled another hole on the opposite side of the faceplate to keep things balanced.

I used bolts instead of screws or hot-melt glue because I used heavy metal ingots and I really didn't want them to turn into UFOs! :no:

Also, although this type of balancing will stop the lathe from vibrating so badly, you need to remember that the wood is still unbalanced! I found that when roughing out, I had to keep stopping after removing X amount of wood and rebalancing, although I'd imagine that this wouldn't be a worry if you're already in the finishing stages.

I've seen similar disks made from plywood that are slotted like cole jaws. The idea is that you can mount this behind the chuck (ie. unscrew the chuck, slip the disk on, screw the chuck back on) and then move weights in/out the diameter of the disk until things balance nicely. I've been meaning to make myself one of these because it'd save a lot of time and fiddling, but like most projects, well... I'll get a round tuit one day. :-

[reeves]

:worthless:

[rodent]

Ca sounds great Sebastiaan but i prefer to use sanding sealer , its cheaper and you can cover a greater area quickly . and it works ( well most of the time ) try and see .

[OGYT]

All the above. Plus, you might try a 50/50 mix of lacquer/thinner, which dries much faster than the CA. It does help, along with very light cuts and higher speed... I know... it's out of balance... try Skews idea along with the 50/50 mix, and it might work a treat.

[PAH1]

Another possibility is that you have too much outward pressure on the gouge as you are doing this, leading to removal of too much material in the softer wood. This leaves a big problem when sanding as you have hard wood that finishes nicely and soft that never sees the abrasive. A couple of tricks are to reverse the sanding direction or learn how to shear scrape.

[Frank&Earnest]

Half suggestion to the poster, half question to the experts.

In situations like this, if the piece allows it, I work from the side with the skew or a scraper, like a metal turning motion, so that there is no perpendicular pressure. Does this make sense? Seems to work for me.

[Skew ChiDAMN!!]

In situations like this, if the piece allows it, I work from the side with the skew or a scraper, like a metal turning motion, so that there is no perpendicular pressure. Does this make sense? Seems to work for me.

That's more or less how I'd approach it, once I'd damped the vibrations down to manageable levels. Enough bevel-pressure to keep control of the tool, but not enough deform a hollowed piece. (Unless it's really, really thin - in which case I'd be using the ol' grit gouge anyway. :) )

[Sebastiaan56]

That's more or less how I'd approach it, once I'd damped the vibrations down to manageable levels. Enough bevel-pressure to keep control of the tool, but not enough deform a hollowed piece. (Unless it's really, really thin - in which case I'd be using the ol' grit gouge anyway. :) )

Hi guys,

Thanks for all of your well thought out responses, I'll post some pikkies when I get some tonight. I think Skew may be right in that its soft heart wood and much more substantial outer growth. The hard stuff polished like glass but the crumbly stuff, well a lot of sanding sealer later...

Sebastiaan

[Sebastiaan56]

Hi all,

Here it is, at last...., the first pikkie shows the L/R divide in the timber, the RHS is the hard stuff, the LHS the softer section. In the second, the soft section is to the rear of the bowl, in the third the soft section is on the LHS and some more of the soft grain and tearout on the front. The last is the beautiful glassy finish on the harder timber. Pity I couldnt get the chatoyance.

Now the whole foot needs to be redone but Im going to rest it a week as I'm sick of the shaking. The balance point for the bowl in about 1.5cm into the heavy section. The bowl is about 250mm wide and 55mm deep. There is quite a marked difference in density and hardness. This made sanding a pain as the softer section sands more easily and increases the unbalance. It also tears out more easily. The harder section is a joy in comparison.

I mostly used the scraper, it spat the skew back at me and the gouge dug in and tore out about 1/2 mm deep in the soft sections, the scraper only tore out 1/4mm. It had a couple of coats of sanding sealer but in retrospect it probably needed the laquer. The CA filled a couple of little holes but these dug out either side later on. Waste of time in this case.

Skew, next time I'll explore the counterbalance idea. Im sure the bearings on the lathe copped a hammering. I'll just have to learn about faceplate mounting. Even then to reverse it to finish the bottom the shakes would continue, but it may make the front side a lot easier to manage,

As I said, thanks for all of the input.

Sebastiaan

[Skew ChiDAMN!!]

Very nice, considering the situation. :thyel:

[BANNED]

Hi Sebastiaan56,

Shame that some timbers are a total mongrel to work with, and we have to spend so much time with them, in your case it did turn out pretty nice.
I'm not sure how you want to finish/fix the broken foot, as a suggestion, if you like to keep the original appearance, I would remove the rim still left, and I would cut a recess of 4/5mm deep and the some thickness as the existent one, in the same place. Cut from the same timber species a rim to replace the broken one, no forgetting to leave it 4/5 longer for the recess. I would finish the new rim before gluing it with white PVC, wipe the excess glue with a wet rug, and let it dry. I believe a nice tight fit and you wouldn't need to do much more to it.

I tent to get plenty of wood like that, one side too heavy the other too lite, one side too hard, the other too soft. When weight is the only problem, I soak the lite part with water (normally put it upright in a bucket and fill up with water until the desire level is reached) live it there overnight, until you ready to turn it.

If part of the timber is too soft, apart from been lite, I soak the soft area, using the bucket technique, but use Fungishield or Prooftint Pine Sealer from FeastWatson, instead of water, for the same amount of time. The next day remove the timber out, and with the wet part down, live it to dry for a hour or so. As soon as the "surface dry" appearance is reached, back into the bucket but this time, with sanding sealer right to the same level. Live it overnight, remove from bucket and let it dry (cure) for at least 2/3 days in the shade.

The bucket is any container with enough size to accommodate normally half of the timber blank, when turn into its side (angle), normally 1 litre of liquid is enough for each stage, with left overs re-usable time and time again. For some patchy areas, sometimes a 1 mm drill bit, and a syringe with a large needle, are a preferred choice.

Again, this weight/dry wood stabilisation procedure, has given me some excellent proved results, one of a few methods I learn through the years.
Something you or anyone, could try one day.:2tsup:

Cheers
GV

[Sebastiaan56]

Hi Sebastiaan56,

Shame that some timbers are a total mongrel to work with, and we have to spend so much time with them, in your case it did turn out pretty nice.
I'm not sure how you want to finish/fix the broken foot, as a suggestion, if you like to keep the original appearance, I would remove the rim still left, and I would cut a recess of 4/5mm deep and the some thickness as the existent one, in the same place. Cut from the same timber species a rim to replace the broken one, no forgetting to leave it 4/5 longer for the recess. I would finish the new rim before gluing it with white PVC, wipe the excess glue with a wet rug, and let it dry. I believe a nice tight fit and you wouldn't need to do much more to it.

I tent to get plenty of wood like that, one side too heavy the other too lite, one side too hard, the other too soft. When weight is the only problem, I soak the lite part with water (normally put it upright in a bucket and fill up with water until the desire level is reached) live it there overnight, until you ready to turn it.

If part of the timber is too soft, apart from been lite, I soak the soft area, using the bucket technique, but use Fungishield or Prooftint Pine Sealer from FeastWatson, instead of water, for the same amount of time. The next day remove the timber out, and with the wet part down, live it to dry for a hour or so. As soon as the "surface dry" appearance is reached, back into the bucket but this time, with sanding sealer right to the same level. Live it overnight, remove from bucket and let it dry (cure) for at least 2/3 days in the shade.

The bucket is any container with enough size to accommodate normally half of the timber blank, when turn into its side (angle), normally 1 litre of liquid is enough for each stage, with left overs re-usable time and time again. For some patchy areas, sometimes a 1 mm drill bit, and a syringe with a large needle, are a preferred choice.

Again, this weight/dry wood stabilisation procedure, has given me some excellent proved results, one of a few methods I learn through the years.
Something you or anyone, could try one day.:2tsup:

Cheers
GV

Mate, thats dedication, Im not sure I would bother. There is plenty of Crapiata in the world :wink:

Sebastiaan

[reeves]

mate just ditch the foot and flatten it off. Nice bowl anyways, sassy can be a very capricous wood to work and each peice seems to give a slightly different result..it doenst like being taken too thin or it breaks...;-)

i find it can take quite a while to get used to how each differnet wood may behave on the lathe...

jhave fun !