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Mobyturns
23rd August 2015, 10:33 AM
In another thread I was asked,


Mobyturns,
I'd be interested to underststand what it is about the P&N skews that you don't like in their standard form?


Short answer - in standard form - two things the square corners & the finish of the steel. Both can be remedied easily if you have the time and the gear to modify them.

This is a very good topic - how and why we select the tools & tool profiles we use.

First off a couple of links to very good resources.

Jon Siegel - http://www.bigtreetools.com/articles/sharpening1.html has a couple of good illustrations.

Alan Batty is an excellent tutor on the skew & spindle turning - https://www.youtube.com/watch?v=KfeLAHQSbqk (note - Alan is using a square cornered skew with the corners eased with an aris.)

I use skews far more than any other turning tools I have, next would be a toss up between the original 13mm (1/2") Sorby Spindle Master (longer grind) and spindle / detail gouges as I prefer spindle turning which is mostly small spindle items like spin tops etc. My comments are about my preferences for the spindle turning I do and the skews I use and will be very different to a production architectural spindle turner.

My preferences are hollow ground, Figure 8 "C" with the Figure 9 "R" with a blunt included angle more towards 55 degrees & about a 75 degree bevel angle, photos below.


Radiused Corners and not square corners
The reason I do not like most skews as supplied including P & N skews has nothing to do with the quality of the steel, but is about the corners of the tools. I use both long and short points when making spinning tops to cut what are essentially large sections of "beads." IMO square corners make rolling beads more difficult to do fluently as they are more prone to trip up on any small imperfections, nicks & dents, in the tool rest which makes the skew "twitchy" and more prone to catches. This is one reason why "round skews" are popular with some turners. Keep the maintenance up on the tool rest = fewer problems.

Hamlet and a few other makers have "rolled edge" & "radiused edge" or RE skews which suit the way I have learned to use skews. Most of my skews are Hamlets, but I also have a set of Thompson skews & all my skews have radiused edges on all four corners (or both sides). The Thompsons were modified for me before I received them.

Thompson and some other manufacturers supply skews with RE on the short point side only. The thinking being that turners use the RE on short point side to roll beads and the square corners on the long point side to add stability to Vee & pommel cuts etc. If you closely watch videos of gifted skew turners like Alan Lacer, Alan & Stuart Batty etc you will find that the skew is almost always rotated slightly off vertical when making those cuts. In my view the RE is easier to use (less twitchy & glides better) with a wider "footprint" on the tool rest but trades off a little with the support or contact on the tool rest being / not being closer to directly under the cutting section of the skew edge.

Heft
I like a skew that has what I call "heft" - weight and rigidity, something that I believe contributes a lot to the stability of a skew and the quality of the finish off the tool. Oval skews are much lighter in cross sectional area & are far more prone to vibration. All of the oval skews I have used exhibit vibration in normal planing cuts but they are great for cutting fine deep Vee cuts. They are still twitchy, and the very narrow edge will find and follow any nick in a tool rest when used on edge. However I like to use an original Sorby Spindle Master (longer grind) which exhibits many of the same "faults" of an oval skew. The Thompson skews have a thicker section which I am growing to prefer over the Hamlets.

Steel
Whether a tool is M2 HSS, 2030, 2060, V10 or V15 does matter for convenience reasons but the primary objective for a skew is a very keen edge. If a skew can be sharpened to a keen edge & it holds the edge for an acceptable length of time then it is a good skew in my book. Most turners will say the edge holding or wear resistance matters greatly, and means lest trips to the grinder. Partly true. I grind skews infrequently and hone frequently using a diamond stone and Eze Lap hones & often end up with a slight curve in the edge toward the long point from the constant honing. Other often overlooked desirable features of a skew are the quality of the steel finish, which allows the tool to glide over the tool rest rather than drag, & how brittle the edge may be (see below).

Profile
Allan Batty's video explains angles at the 2:45 mark. Our harder Australian timbers generally mean higher wear on fine edges, so the solution is harder steel and or less fine cutting edges on our tools. Harder steel generally equates to more brittle and more difficult to sharpen. My preference is for a "blunter" included angle, towards 55 degrees, which is more robust but not as "sharp" and does not cut as efficiently as a finer included angle. I use skews with varying bevel angles and included angles as each has benefits. Finer included angles will wear faster and are more prone to damage from embedded objects and some of our harder woods but they permit deeper & finer Vee cut detail etc. Tamarind kills edges on skews very fast.

I use & much prefer a pretty traditional skew grind & vary the angles to suit my preference. Other very good spindle turners like Powder Post & "Retired" have quite different preferences that work well for them, neither is "better" or "correct" in my opinion and it is always a good topic for discussion over a beer.



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Flindersia
23rd August 2015, 11:01 AM
Really appreciate this Moby. I personally like the P&Ns because they have one long edge rolled, or at least the older ones I have do. I don't know why but I never considered rolling the edge towards the long point as well. Makes a great deal of sense really when you put it in that light. Your note has opened up my mind to some further experimentation.
Thanks

Mobyturns
23rd August 2015, 11:13 AM
Really appreciate this Moby. I personally like the P&Ns because they have one long edge rolled, or at least the older ones I have do. I don't know why but I never considered rolling the edge towards the long point as well. Makes a great deal of sense really when you put it in that light. Your note has opened up my mind to some further experimentation.
Thanks

With the tops in the photos the pine ones are straight off the tool so 400# finish of the skew is very achievable with practice BUT the profile & presentation of the skew has a lot to do with the quality of the cut as well.

The large "bead" on the upper surface of the top is cut long point down and the point slightly below center (I think - never really thought to hard about that) in a long sweeping arc.

The included angle on the bevel of the skew makes a big difference to the starting and finishing positions of the tool handle to maintain bevel contact through the cut. I also break the rules in that I start that particular cut with no bevel support - takes a while to master. When you think of it it does not matter if you use the short point or long point on that cut as neither has bevel support at the commencement of the cut on a spin top with a thin edge.

chuck1
23rd August 2015, 05:03 PM
Here are photos of my go to skews for spindle turning. The half by half is used for beads and fillets and V cuts on posts.
it is boliher S600 and it is used as a parting tool.
the angles are grinded free hand the honed on my old India combination stone.
They get a fair bit of use at work. From turning pine to recycled tallowood.
I have a fair few skews in the rack at home. Some are 6mm by 6mm

Pat
23rd August 2015, 05:35 PM
Moby, you give me much to think about. I use the long edge a fair bit and I never thought of relieving the top edges :doh:

Chuck, I managed to pick up a 32mm Bohiler S600 Skew from an older gent. It is now my favourite skew and the 3mm parting tool is the go to toy.

Old Croc
24th August 2015, 01:45 PM
+1 for P&N skews. After a lesson from Retired at the Prossie Turnout, I bought one from Vermec, radiused the edges, reprofiled it on the Tormek and have never looked back. I was one who has always struggled with a skew, but since i got this one set up I just grab it and turn and turn and turn some more. It just feels a natural part of turning now. As usual, very good post Moby.
rgds,
Crocy