Turning hollow forms (boxes) from sapling sections

[JB]

I'm planning on having a go at turning hollow forms (boxes, with lids) from 100 to 150mm long and appx 100 diameter sections of young red ash/coopers wood. These are from saplings about 5 to 10 years old. Any advice on technique, suggested wall and base thickness, drying methods would be welcome as I don't want to waste too much time or get discouraged from going about it the wrong way. I'm already finding hollowing out the end grain quite challenging. The outside will be left as is with bark on.

[Skew ChiDAMN!!]

OK. End-grain turning. Love it! :2tsup:

First thing: when hollowing into end-grain, you use the chisel in a reverse-manner.

Reverse manner? :oo: What am I talking about? Well, when hollowing a bowl you cut from the rim in towards the centre so as not to "lift the grain," yes?

When working into end-grain, the blank (and thus the grain pattern) has been mounted 90deg. to 'normal bowl mode' so you should work the other way: start in the middle and cut outwards towards the rim! For exactly the same reason... because if you don't you're cutting "into" end-grain instead of across, and will end up with terrible tear-out.

Assuming you're using a bowl-gouge, of course. :D

For jobs of the size you're talking about, I prefer to use an oland tool with a bull-nosed scraper grind to remove the bulk of the material. Stopping, say, 5mm from the final interior wall and 1cm from the bottom, so I can clean up any tear-out from this... ummm... "brute force removal."

I'll use a good bowl gouge to clean up the sides, but more often than not I'll shear-scrape the bottom surface with the oland tool... and be prepared to do a lot of sanding down the bottom of the well. :- (Because it's all end-grain & awkward - if not impossible - to clean up with a bowl gouge due to it's 'depth' in the box.)

I like the oland tool because it's thickness minimises chatter when overhanging the tool rest so far. But a good, thick scraper will do the trick if you can manipulate the tool-rest in close enough for support..

(Forgive me if I'm pointing out what's obvious to you, but I'm sure there are those who are reading who've more or less just thought "Oh! I hadn't thought of that!" ;) )

[JB]

Thanks for that, some new info for me.

Don't have an oland tool but do have several good scrapers so will use those to finish. Do have a bowl gouge!

Thinking a rounded bottom might reduce some of the difficult tool work - so long as the extra thickness wall on the radius doesn't interfere with even drying of green wood?

[Skew ChiDAMN!!]

It shouldn't, so long as you don't store the finished pieces in a "desert dry" area. :)

D'you have any idea what sort of wall thickness you'll be aiming at? Because they're natural sided, the wall thickness will vary... it'll help if you mount it between centres and mark some circles on the ends so you can get an idea just how much variation you'll get.

Personally I'd be happy if the thinnest parts of the wall will be around 5mm and the thickest around 1cm. It depends on the piece, of course.



Oh... while I think of it... mounting the blank! You up for a few hints? Bad luck, here they are anyway. :D

Because you won't be roughing the outside round, you'll want the black mounted as accurately as possible. And because scraping can apply more "leverage" than a cutting action, it's a good idea to mount the piece as securely as possible. (While you may start with tailstock support, eventually it will get in the way and you'll be spinning a lengthy object solely from the headstock.)

Although using a chuck can give adequate grip, I believe this sort of thing is best mounted on a faceplate. Provided you don't mind losing an inch or two of overall blank length, anyway. I've pried loose way too many goblets from chuck jaws, never lost one yet from a faceplate. (Well... not from going "too hard" with a scraper, anyway. :rolleyes: )

So, I'd mount it between centres, taking my time and rotating the piece by hand until I got it just right, then power up the lathe and square off as much as possible of the headstock end. Remove from the lathe and sand/cut/whatever any protruding 'nubbin' left where the spur drive was so the whole end is flat enough to mount on a faceplate. It's also a very, very good idea to 're-punch' the centre mark left by the drive spur before sanding that part away, so you still have a reference point!

I have a metal rod that just fits nicely thru the headstock (think of it as a sharp, pointy knock-out bar) which comes in handy for re-alignment when screwing to the faceplate.

I replace the drive spur with the faceplate, poke this rod through until I can align the tip of the rod with the centre mark left by the drive spur, put the tail spur in the matching divot at the other end and tighten the tailstock. This means the blank is lined up exactly as it was when just between centres and I can drive the screws home in the faceplate. :2tsup:


Huh. It all looks complicated when I look up at this formidable wall of text, but really it's a very quick & easy process. I just make it 'seem' otherwise. :rolleyes:

[JB]

Yes I'm aiming for 5mm to 1cm

I have jaws that make life easier (see photo first post) but take your point about face plate mounting.

Regarding cutting direction...I agree that from inside out is with the grain, but I'm getting some nasty catches if I turn the chisel over too far. Whereas out-to-in I can rub on the bevel.

[JB]

Do have a bowl gouge!



Now I have two:(

[Osbojo]

That's definitely an oopsie! only happened to me once with a crappy roughing gouge when I forgot rule number one "engage toolrest before the wood". I agree that Olanders are great for hogging out and are real easy to make, try googling them.

[Skew ChiDAMN!!]

Ouch!

[JB]

Thanks for the feedback guys.

Happy with this raw and rustic look achieved with the scraper shown. Yes, I confess the gouge must have contacted the wood before the toolrest. But I am a curioius about the difficulty of gouging from inside to out: it seems a very fine line between okay and a nasty catch.

Now I'm wondering about wet sanding, or do I let the piece dry then sand. If I let it dry I will have to leave the spigot attached which means 2cm of base thickness which will slow down the drying (and increase the chance of cracking?)

[TTIT]

Skew has given you some good positive info there so I'm gonna come and rain on your parade :U You're going to be pushing the veritable uphill to stop Red Ash splitting wide open with the heart in it like that :no: Even if you were turning down the outside to give an even wall thickness, the bottom is going to pop wide open as it dries :C BUT, there is something that might help. You could try drilling a hole about 40mm or so through the bottom to allow the 'cylinder' to shrink evenly, then plug it later on with the same or a contrasting timber. :shrug: Just a suggestion :B

[JB]

U You're going to be pushing the veritable uphill to stop Red Ash splitting wide open with the heart in it like that B

Because it's red ash, or whatever the species?

[Colin62]

Yes, I confess the gouge must have contacted the wood before the toolrest. But I am a curioius about the difficulty of gouging from inside to out: it seems a very fine line between okay and a nasty catch.

Try using a spindle gouge for turning the inside of end-grain bowls, they're less prone to catches.

[TTIT]

Because it's red ash, or whatever the species?You will get away with it on many species but Red Ash (http://www.ttit.id.au/treepages/soapbush.htm) ain't one of them! - renown for cracking open even in board form! :no:

[JB]

You will get away with it on many species but Red Ash (http://www.ttit.id.au/treepages/soapbush.htm) ain't one of them! - renown for cracking open even in board form! :no:

I'll keep you posted. I suspect my 100mm diameter sapling offcut will be a lot less volatile than the beast you tackled on your link (http://www.ttit.id.au/treepages/soapbush.htm)