Bowl turning technique - grain direction

[CHJ]

...... ...still cant take the forces) then messing up with badly formed dovetails on Axminster C jaws ...but finally figured that if I get my skew 'scary' sharp (and I know sharp is a thing of debate) and am super careful then even in rough old green fir the dovetail is kinda good enough ...so long as I dont hack too fiercely at the turning!
Keith

Keith are you saying you are using a skew for turning on chuck mounted 'bowl/box' projects? you should only be using a skew for basic stock removal on spindle work.
If ever you get a catch on something like a Bowl blank you could be in serious trouble, a skew catch on a spindle can be bad enough, one diving into a bowl blank could lead to serious injury.

You may see videos and demonstrations with someone being 'cleaver' with a skew but like you also see many demonstrators not wearing any face protection, sooner or later one of them gets bitten.

 

[Keithie]

I hadnt thought of skew use like that Chas ...but I suspect you're right again ...though it might be a grain direction thing ..

On a normal spindle I use a skew for 'planing', 'peeling' (including tidying up an end face), making 'V' cuts and forming beads (typically after a V cut)

On a bowl blank which is end grain (ie a spindle blank being used as a bowl blank) I use the skew to plane the cylinder (after roughing) and for cleaning the end and also making the dovetail on the end (which is what I wasreferring to above)

On a bowl blank with the traditional orientation (I've done three of those only...but have ordered some pre-made bowl blanks now) I use a bowl gouge to plane the cylinder and a bowl gouge to clean the end ...and indeed shape interior and exterior (plus a parting tool & round nose scraper at times!) . I was using a spindle roughing gouge to rough out the cylinder from its 'almost' circular shape but you quite rightly pointed out the risks there ..so now I use the bowl gouge for that. I hadnt considered using a skew on a correctly orientated bowl blanks...though I did use it to shape the interior of the wide flat bangle on the Cole jaws I made a while back (but that was end grain bowl orientation again) ..till you pointed out the risks! I've not made dovetails on spigots of correctly orientated bowl blanks tet, as I've been using the C jaws internal which has a simple 'ridge' so I use a 1/8 parting tool to form that in my spigot. Having said that though, I dont have a plan for how to make a dovetail in a correctly orientated bowl spigot...so would be curious to know the best method.

Thanks though ... better to help me keep safe than not !
cheers

 

[Keithie]

Apart from not being sure how to form a dovetail in the spigot of a correctly orientated bowl blank I did want to check one other thing I may have been getting wrong..

So far I've only made one handle ...for my long hole boring augur ...but I expect, in time, to make handles for most of my turning tools.

The handle I made was from a cherry spindle blank ..

with the grain running along it. Most of the forces it will receive, I guess, are rotational ... but for a gouge or chisel/parting tool the forces are probably different.

So my question is whether this is the appropriate grain orientation for an augur handle and whether it would be the correct orientation for mainstream tools.

I suspect it is for most tools (based on what existing handles look like) but now I think about it, I'm not sure what is best for augur handles ...the only type I've made so far!

 

[CHJ]

Keithie ,

All handles should be from spindle stock orientation, if turned from cross grain they would readily snap in the middle.

Spigot and socket Dovetail slope can be done with a straight Skew gouge laid flat on its side, (NOT in Planing Mode)

Form your spigot and straight sided socket with a parting tool, then form the taper surface with the skew , Flat side down on the rest.

Dovetail Jaws are usually at a 75 deg. angle, if you grind a 1/2" skew front edge slope to approx. this it makes it easy.

See this post for images

You will find tools available with appropriately ground front ends to form the dovetail slope, I've ground one up myself in the past, more trouble than it was worth and never got used, a sharp edge skew cutting in shear mode is far more effective in most woods.

 

[Paul Hannaby]

There's no reason why you can't turn end grain bowls (or hollow forms etc.). Strength is rarely the issue with the average range of woods and wall thicknesses.

Bear in mind that to achieve the cut "with the grain", a side grain bowl is cut from centre to edge on the outside and edge to centre on the inside. For an end gran bowl the opposite applies. A good way of getting the centre to edge cut on the inside of an end grain bowl is to use a ring tool. With some woods you can "cheat" and cut edge to centre with a sharp gouge and light cuts but some woods are less tolerant and will result in torn grain.

End grain bowls allow you to use a whole log section. Where a wood with contrasting heart and sapwood is used, it opens up the possibility of keeping that contrast all round the rim like the one below turned from an african blackwood log.

 

[Keithie]

Thanks Paul,

That's a particularly nice piece you turned there!

I think I'd got my head round the theory of 'inside to outside & outside to inside' and then the opposite way for end grain bowls ... the practice of course being a skill I'm gradually learning (the difficulty being compunded by my inconsistent freehand grinding of my gouges!). I've been trying to resist the easier (?) tools for now and stick with gouges, skews and a 1/8 parting tool (but a round nose scraper ...adapted to make it partly swept on one side .. and a forstner bit have already crept in) while I learn the basics.

For the inside of an end grain bowl (centre to edge direction cutting) I use a 8mm forstner to make the centre hole then try to cut out slowly little by little... putting a couple of safety 'ring' recesses in with a parting tool to stop my gouge skidding all the way out to the edge and knocking a chunk off it (a tip I think Chas gave me) .. any other tips on technique with a bowl gouge for the 'end grain bowl internal inside to out' would be very welcome!

You're quite right about the grain tearing ... I'm using mostly green 'western red cedar' (which I think is probably douglas fir or western hemlock as there's lots of it round here) which soon lets me know about cutting too roughly and sanding unevenly etc .. certainly far less forgiving than the little bits of elm, oak, iroko and chestnut I've used. Do you have any tips (beyond keeping the tool sharp and making very light consistent cuts .. easier said than done!) for minimising grain tearing in green softwoods when I use a gouge ?

I'd also be interested to know how you sanded that blackwood log piece .. I find it tricky to sand smaller parts of pieces well by hand as my fingers are like a bunch of bananas and putting hermes blue/yellow paper on a stick seems to carve more than sand under my guidance! (I'm assuming of course that no matter how clean your cuts are you probably still sand at some grade ?)

cheers

 

[woodpig]

Carbide cuts end grain well. As you can see just past half way in this video you can remove material quite quickly.

https://youtu.be/7A7u_IPPN9s

 

[Dalboy]

There's no reason why you can't turn end grain bowls (or hollow forms etc.). Strength is rarely the issue with the average range of woods and wall thicknesses.

Bear in mind that to achieve the cut "with the grain", a side grain bowl is cut from centre to edge on the outside and edge to centre on the inside. For an end gran bowl the opposite applies. A good way of getting the centre to edge cut on the inside of an end grain bowl is to use a ring tool. With some woods you can "cheat" and cut edge to centre with a sharp gouge and light cuts but some woods are less tolerant and will result in torn grain.

End grain bowls allow you to use a whole log section. Where a wood with contrasting heart and sapwood is used, it opens up the possibility of keeping that contrast all round the rim like the one below turned from an african blackwood log.

As Paul has stated, the cuts however will change slightly if you have an open bowl with a undercut in which case follow how I have indicated in the picture below the outside will be cut in the opposite direction to that of the inside

 

[Keithie]

Thanks Woodpig ...another nice video ... that cutter certainly shifts wood pretty swiftly ..i think it was around 5min15 and on for a bit where in a couple of mins he cut out what would take me probably 30mins!

I'm trying to resist that and similar tool types though, till I get to the point where I've learned how to use the basic tools well enough to make consistent cuts that I'm pleased with ! Does look a heck of a lot easier though!

Thanks Dalboy also ..I'm just starting to try undercuts...but only have (by choice) the basic tools ...all of which are straight. For undercuts like you show in the pic I was thinking (but havent tried yet) about reversing the lathe direction and cutting from the nearside of the bed across ...I'm not sure that's how it should be done though ? presumably its more normal to use a swan neck or hook type tool for that sort of undercut is it? (I understand in your pic though that cutting in the opposite direction for the undercut...as you show..makes sense from a grain perspective ...I'm just not sure how to do it with the tools I have)

 

[Dalboy]

The diagram is only for information and undercutting does not need to be so obvious as I have shown. I have done undercut like in the diagram with normal tools but it did mean that I had to turn the headstock outwards, otherwise it would mean having to lean over the lathe bed.

 

[Paul Hannaby]

Thanks Paul,
I'd also be interested to know how you sanded that blackwood log piece .. I find it tricky to sand smaller parts of pieces well by hand as my fingers are like a bunch of bananas and putting hermes blue/yellow paper on a stick seems to carve more than sand under my guidance! (I'm assuming of course that no matter how clean your cuts are you probably still sand at some grade ?)

cheers

Sanding was done by hand. The wings were done wth the lathe stationary to avoid rounding over the edges. This one was around 8" diameter so it was big enough to get my hand in. For some natural edge bowls, I power sand the edges, it depends on the shape.

 

[Keithie]

Thanks Paul... I guess I'm going to need to get/make sanding machines/tools in due course rather than only holding the paper in my fingers.