Thread: Turning thin without breakage

Originally Posted by apricotripper

So no drivespur. Unfortunetly thats all I've got. Moneys too short to be buying chucks and the like......how about a make shift drive screw ?....Are you shore about that glue idea ? sounds a bit too weak.

I don't have a live centre either. Always used just a waxed up static one. Whats your take on live centres ? .....Which ones shouldn't I buy ?

If we could all afford to buy the appropriate commercial tool for any given job, these forums would be little more than social chatter. A drive screw should work, ditto for glue.

Personally I don't think it matters which centre you have. I think I've mentioned that occasionally I'll use a brad in a jacob's chuck as a dead centre at times? There's a whole range of live centres, steb centres, interchangeable centres, etc. out there... and AFAICT there's no major difference in 'em apart from quality issues. Sloppy bearings, etc.

Some hold certain shapes better than others, but it's a bit like arguing over whether a Holden Rodeo or a BMW is better before you even have a driver's license.

While I'm picking your brain ,,,,,,,how do you go about burnishing profile blades. Do you bother ?
[...]
I just sharpened the bevel at 70 degrees and backed off fairly ruffly, but I didn't burnish........the blade cut cleanly, but slowly, and blunted pretty quickly. Had me backing off the blade after every knob. The bluntening was probably cause it was just regular carbon steel and not say HSS.

I don't bother... else I'd spend more time sharpening/burnishing than cutting. To be honest, I don't like using profiled blades beyomd very basic shapes, precisely 'cos they're too much effort to keep sharp and IMHO don't give the best finish anyway. I'm inherently lazy, I want max. finish for min. effort from my powertools. Else I'd be darksiding.

The same basic cutting principles apply to turning tools as apply to hand-planes. As you know, (I've seen your thread! ) a skewed blade cuts better and keeps its' edge longer than working square across the grain. This is why I use a basic scraper at a skewed angle... and rely on skill, patience, measurements and a helluva lot of luck to get accurate copies.

The CS instead of HSS certainly doesn't help, but I think the real problem is that in sharpening by backing off the blade you're not creating a burr. And it's the burr that does most of the cutting on in scraper mode. I think this is true of scraper-planes as well?

Ta ribot and skew.

Originally Posted by Skew ChiDAMN!!

Some hold certain shapes better than others, but it's a bit like arguing over whether a Holden Rodeo or a BMW is better before you even have a driver's license.

Ta. I won't put much thought into it then. stick with me wax a static tailstock.

Surprised about the glue I must say. Hot glue gun you say ? That stuff granny uses to stick her paper daisys together with ? buy it at craft stores. Dribbles off in big strings like cheeze off a pizza ?

Originally Posted by Skew ChiDAMN!!

I don't bother... else I'd spend more time sharpening/burnishing than cutting. To be honest, I don't like using profiled blades beyomd very basic shapes, precisely 'cos they're too much effort to keep sharp and IMHO don't give the best finish anyway. I'm inherently lazy, I want max. finish for min. effort from my powertools. Else I'd be darksiding.

Well, you've got me there. I thought the idea behind these profile blades was to speed things up, cause you don't have to fiddle about with marking out and spindle gourges to get identical pieces the same.

As long as you can keep the thing sharp I suppose. When I cut those profiles from the plane blades I only ground the bevel once. Whenever it bluntened I wouldn't touch the bevel, I'd just lap the back hard ,,,,,that way I didn't have to fiddle about spending a great deal of time ensuring I didn't stuff the profile up......I thought that made the process justifiable.

Originally Posted by Skew ChiDAMN!!

The same basic cutting principles apply to turning tools as apply to hand-planes. As you know, (I've seen your thread! ) a skewed blade cuts better and keeps its' edge longer than working square across the grain. This is why I use a basic scraper at a skewed angle... and rely on skill, patience, measurements and a helluva lot of luck to get accurate copies.

The CS instead of HSS certainly doesn't help, but I think the real problem is that in sharpening by backing off the blade you're not creating a burr. And it's the burr that does most of the cutting on in scraper mode. I think this is true of scraper-planes as well?

Interesting stuff this I think. I've got skewed blades on the brain right now.
This is how it makes sense to me....

I think your right. Its all about removing material with the grain. Ideally slicing it off rather than scratching it off. But as long as the blade moves with the grain. Same stuff as with cross grain work with planes.

And I think your right, if you take a square blade straight(like a normal bench chisel) into the centre of the turning.....thats not slicing, thats tearing, cause the blades taking big hits on the same fibres all at once.

but I think taking a profiled blade in is different, if you drag it a little below the centre of the turning, the curves begin to remove material with the grain (excepting the very top of the hills and valleys). Mate, I do make lots of mistakes, and it took me forever to picture all the angles in me head, but I'm certain of it.

I'm certain because the angles are similar to those I aim for when shaping a plane blade to cut well with the grain. And the finish I got when pushing those profiles in (from those pictures) in was pretty good I thought. Those pictures are straight from the blade. No sandpapeeer. I don't know how I could have ever done them better by swooping in a spindle gouge.....But then, I'm bloody useless with normal lather tools.

So, even though I didn't have a burr on the blade, and there was a lot of scratching going on, because the blades were angling in over the fibres and not catching under them, the finish was good.....if that makes sense.

you think I'm a ####en nutter don't ya

Originally Posted by apricotripper

Surprised about the glue I must say. Hot glue gun you say ? That stuff granny uses to stick her paper daisys together with ? buy it at craft stores. Dribbles off in big strings like cheeze off a pizza ?

Clear plastic sticks you put into a "heat-gun" and make spaghetti with. Yeah, that's the stuff. It's surprising how effective (and how many applications it has) in turning. Best thing is, to seperate it later ya can just bang it in the microwave or blow it with a hairdryer.

Well, you've got me there. I thought the idea behind these profile blades was to speed things up, cause you don't have to fiddle about with marking out and spindle gourges to get identical pieces the same.

As long as you can keep the thing sharp I suppose. When I cut those profiles from the plane blades I only ground the bevel once. Whenever it bluntened I wouldn't touch the bevel, I'd just lap the back hard ,,,,,that way I didn't have to fiddle about spending a great deal of time ensuring I didn't stuff the profile up......I thought that made the process justifiable.

In turning metal, that's true. Not really so with wood. The thing is, mounting a plane-blade backwards won't make it work well as a scraper plane. Try dragging a razor-blade backwards over yer fore-arm and I bet it doesn't shave. It's not cutting, it's just slowly abrading the hair away. For a scraper blade to cut it needs the burr left behind. The bevel's really only an artifact left over from creating the burr... as well as helping to support it.

These backward angled blades are whole new world of thinking in themselves.

Interesting stuff this I think. I've got skewed blades on the brain right now. This is how it makes sense to me....
[...]
but I think taking a profiled blade in is different, if you drag it a little below the centre of the turning, the curves begin to remove material with the grain (excepting the very top of the hills and valleys). Mate, I do make lots of mistakes, and it took me forever to picture all the angles in me head, but I'm certain of it.

So the blade's profiled to suit the angle you're cutting on and not to match the final knob profile? Smart lad, you've certainly given it some thought. I was a bit wary of brining it up, I'm glad I don't have to. It usually takes a while to explain... people can't seem to get past the idea that a profile & a template are two different things... and a profile doesn't have to be introduced square on.

But, as I've said (and will probably repeat frequently over the next few years) a scraper really needs the burr to cut properly. Sure, it'll work so-so without one but to make it cut better and hold it's edge longer, well... To make a burr you need to work the bevel, which'll change the overall profile slightly unless you make minor corrections, which makes 'em fiddly to use.

Of course, your way does work. I won't try to say that what you've accomplished so far is a figment of your imagination. But it's like comparing the aforementioned skewed plane to one cutting square across the grain. There's a noticeable improvement... if you're willing to put up with the inconveniences that go with it.

So, even though I didn't have a burr on the blade, and there was a lot of scratching going on, because the blades were angling in over the fibres and not catching under them, the finish was good.....if that makes sense.

It does. I'd hazard a guess and say you're using a forgiving timber too. Like most any w/work, that's also a major factor. Try the same profile with oregon, radiata or a similar wood with "loose" grain structure and let me know what you think.

you think I'm a ####en nutter don't ya

Not at all! Take everything you know about plane blades and it will still apply to turning chisels. Except that the rules of sharpening are stood on their head. Throw in a few other complications, such as some tools need to be bevel-rubbed while others shouldn't, etc., etc. and then you're getting close to nuthouse territory.

Especially once you get into making your own turning tools.

Originally Posted by Skew ChiDAMN!!

Clear plastic sticks you put into a "heat-gun" and make spaghetti with. Yeah, that's the stuff. It's surprising how effective (and how many applications it has) in turning. Best thing is, to seperate it later ya can just bang it in the microwave or blow it with a hairdryer.
:

Ta. Well, I'm going to have to get a gun....and a dryer (or create a stink, by pinching the wifes )

Originally Posted by Skew ChiDAMN!!

In turning metal, that's true. Not really so with wood. The thing is, mounting a plane-blade backwards won't make it work well as a scraper plane. Try dragging a razor-blade backwards over yer fore-arm and I bet it doesn't shave. It's not cutting, it's just slowly abrading the hair away. For a scraper blade to cut it needs the burr left behind. The bevel's really only an artifact left over from creating the burr... as well as helping to support it.
:

I agree entirely. A burrs a good thing.

I took a photo of a photo from that leneod lee book ' A complete guide to sharpening' ......I've attached it to this post.....What do ya think ? ...Its a jig with a carbide rod sticking out to burnish your scraper at 10 degrees...Which I thought was clever. Probably been around for years. I don't know.

Anyway, I was thinking of making up something similar to burr into the valleys and over the hills of those rough profiles I made from those plane blades. But with a smaller rod....something real small to get into those tight curves, like an old 2mm HSS drill bit shank maybe.....Maybe just drill it into a block of wood at about 10 degrees, loosen the chuck and just leave it there.....clamp the wood in the vise and burnish away sort of thing.

How would that fail do you think ? .....and also.... (sorry mate)

do you know of thrifty way of getting hold of HSS blanks ? Decent sized. Thinking it be better than those carbon steel plane blades.

Originally Posted by Skew ChiDAMN!!

So the blade's profiled to suit the angle you're cutting on and not to match the final knob profile? Smart lad, you've certainly given it some thought. I was a bit wary of brining it up, I'm glad I don't have to. It usually takes a while to explain... people can't seem to get past the idea that a profile & a template are two different things... and a profile doesn't have to be introduced square on.
:

oh don't think I'm being that clever Skew.....the simple picture I had in my head was, that with the blade going in below the centre of the turning, had all curves going off the valleys in my blade cutting (I mean scratching ) with the grain. That sort of told me.......' as long as I point it in below, draging the blade, similar to how a card scraper leans forward the thing will make a smooth cut, regardless of how the profile waved about. '.....which mean't just deciding on what profile. Anyway forget it. I'm confusing myself now.

Originally Posted by Skew ChiDAMN!!

But, as I've said (and will probably repeat frequently over the next few years) a scraper really needs the burr to cut properly. Sure, it'll work so-so without one but to make it cut better and hold it's edge longer, well... To make a burr you need to work the bevel, which'll change the overall profile slightly unless you make minor corrections, which makes 'em fiddly to use.
:

Good point..... still thinking its worth a try, at least for my own education....Thinking now-> sharpen the bevel intially, buff the contours of the bevel slightly on occation with carving buffer (probably start to round a bit, so not too much)....but generally to sharpen just back off heavily.....maybe even with a coarse grit first to rip off the previous bluntening, then jap stone to clean up a bit, then burnish with this drill bit in the block idea (fingers, toes, testicles crossed) and hopefully find a HSS blade 3" thick to begin with, to deal with all that backing off

Originally Posted by Skew ChiDAMN!!

I'd hazard a guess and say you're using a forgiving timber too. Like most any w/work, that's also a major factor. Try the same profile with oregon, radiata or a similar wood with "loose" grain structure and let me know what you think.

Probably right. I don't know what I used actually. Pinched it off the MIL's wood chop pile. Pretty shore its red gum. But I've given up trying to be clever in remembering wood species.

But, I know what you mean. Begining to think its a good general test of skill.....ie. being able to cut #### soft timber well cross grain. Similar problems with cross grain hand planing. But even worse with lathe work, I'd imagine, with all that speed.

I'll sharpen up the profile plane blade as best I can and try it out on some radiata....and see what happens. Guessing the hills in the profile will rip out in places.....see what happens. . Ta mate . Good talking with you.

Originally Posted by apricotripper

I took a photo of a photo from that leneod lee book ' A complete guide to sharpening' ......I've attached it to this post.....What do ya think ? ...Its a jig with a carbide rod sticking out to burnish your scraper at 10 degrees...Which I thought was clever. Probably been around for years. I don't know.
[...]
How would that fail do you think ?

I'll let you know after I try it. It's a new one to me, but I'm no Raffan. Sounds like it'd be almost perfect for profiled scrapers... and it might have me rethinking a few ideas too.

do you know of thrifty way of getting hold of HSS blanks ? Decent sized. Thinking it be better than those carbon steel plane blades.

McJing is the first commercial supplier to pop to mind... check out both their "woodworking/turning tools" and "engineering/turning tools" sections. I'm not sure whether they carry stock suitable for profiling though. About 6" x 1.5" x 3/8" is probaby the widest, from memory. (At least, that's the largest I remember drooling over. )

The big ol' multihead moulder I used to operate for a crust took solid HSS knives but I can't get any more of them, dammit. If there's any joinery's near you, it wouldn't hurt to ask about their throwaways.

oh don't think I'm being that clever Skew.....the simple picture I had in my head was, that with the blade going in below the centre of the turning, had all curves going off the valleys in my blade cutting (I mean scratching ) with the grain.

Yeah, but you thought about it before having an "uhoh" moment.

Good point..... still thinking its worth a try, at least for my own education....Thinking now-> sharpen the bevel intially, buff the contours of the bevel slightly on occation with carving buffer (probably start to round a bit, so not too much)....but generally to sharpen just back off heavily.....maybe even with a coarse grit first to rip off the previous bluntening, then jap stone to clean up a bit, then burnish with this drill bit in the block idea (fingers, toes, testicles crossed) and hopefully find a HSS blade 3" thick to begin with, to deal with all that backing off

By all means, go ahead! I'll be interested in your findings, too. It may not be suitable for production turning but if it works for you, that's all that matters, right? I use a few... ermmm... "frowned upon" methods I also like to use. And it's always nice to have an alternative method up your sleeve, for those times when more traditional methods just don't cut it. (Sorry... couldn't resist that. )

Probably right. I don't know what I used actually. Pinched it off the MIL's wood chop pile. Pretty shore its red gum. But I've given up trying to be clever in remembering wood species.

You'n'me both. I really, really, REALLY wish I'd taken the extra few mins to label each bit of wood in my curing shed after cutting/stacking it instead of thinking "Oh, I know what that is" and pissing off for a well-earned brew. [sigh]

Apricot,

The device you posted a pic of can be purchased. One is made by Veritas. See the Timbecon online catalogue.

Claims are that it actually raises an edge, not just a burr.

Never used one but would be interested in what it can do.

Originally Posted by Skew ChiDAMN!!

I'll let you know after I try it. It's a new one to me, but I'm no Raffan. Sounds like it'd be almost perfect for profiled scrapers... and it might have me rethinking a few ideas too.

I'll try it too when I get a chance and post here. But who knows. Might be crap too. Spose just have to keep trying.

Ta for the link. And I'll make a visit to the local boys,,,,try and catch em in a smoko and ask about throwaway blades.....it'll have em rolling their eyes, and calling me a bloody scrounger though...betya.

And thanks Rsser..... didn't know you could buy them. I'll check it out.

Sorry, should've been clearer: it's designed for a handled scraper since it needs the shaft of the HSS to lever off.

i ahve been using a diamond honing pad after grinding the shape. This helps a lot keeping a good edge without too much drama or loss of steel.

Originally Posted by rsser

Sorry, should've been clearer: it's designed for a handled scraper since it needs the shaft of the HSS to lever off.

If apricot's planning on using it for any length of time, I'm sure it'll end up spouting a handle of one form or another.

Hmmm... that could be an interesting project in its' own right. No, no, I've enough on my plate, I don't need any more. Get out of my head! Out, out damned spot! Bloody ideas, circling around like birds of prey... I can see it'll be another sleepless night...

Yep, you got the bug Skew ;-}

Time for more machines and materials - not a cure, only a palliative.

btw, like Reeves, I touch up my tools with a diamond lap to keep them fresh. Suspect too much since comparing with an off-the-wheel touch up. Could have been getting a dual bevel.

Ditto the diamond lap for my gouges and more... "normal" scrapers.

But they're not much chop on concave profiles. I used to use a SS burnishing rod (salvage from an old dot-matrix printer) for my ring- & hook-tools, but I don't now. Not sure why; probably 'cos I don't use 'em often and am inherently lazy.

I like the idea of that plate... something that can just be clamped near the lathe and is always there, convenient to hand.

Reeves don't know if this will help but this was a site that had some info on crochet hooks, hope it helps, http://www.turnedtreasures.com/proje...chet_hook.html
Cheers
Darren