close look at new tools

[woodfarmer]

I have at last made myself a grinding station. I wanted to just sharpen the new tools I had with the lathe and preserve the original grind from the manufacture to reduce metal removal. first the 1/2 bowl gauge. I had problems using this on a bit of hard old oak beam, mostly with tearing. Looking carefully at the original grind this was flat cut from teh face of a grinding wheel and not concave from the outer periphery. Actually ALL of the original grinds were done the same way. Flat not hollow ground. This makes a lot of sense to me as I am used to metal turning tools and giving vertical support to the cutting edge is a big thing. about three light wipes rolling it on the platform gave me a shiny surface which when tested both on the oak and a bit of pine cut beautifully. So I also "touched" my 3/8" bowl gauge as well as they both had the same original angle as did my large roughing gauge (45 degrees) none of this is what most books recommend . The 1/2" bowl gauge did not have a even round original grind but as I was able to get an edge in all the important parts I left the original side alone. eventually after a few sharpenings I will get down to that bit. Apart from needing to make jigs for other angles the basic grind station will do all of the tools I have except my skew chisel.. This came as a surprise because the parting tool is tapered from the middle to each edge and I was wondering how to construct something that would hold it square. Then I realised the the original grind was not square, It had been held down on one face and ground, then rolled over and held down on the same side and ground again. so the tip is slightly skewed. I have used it and it works fine out of the box. If you look closely you can see the tip is not dead central with the centre of the tool. Assuming that is that I can post a picture.
the spindle gauge I haven't sharpened yet as it requires another angle to be set in the

grinding station. the thing to note here is that it is lop sided as one side is ground back more than the other. Is this intentional or a manufacturing mistake? I dont want to make it even if it is meant to be lop sided.

EDIT the picture came out in the wrong order. the first is the offset spindle gauge.
the second is the 1/2" bowl gauge and the last is the parting tool as it came from the manufacturer.

 

[John. B]

I have found that most newly bought turning tools need to be sharpened/ profiled to one's own fancy, however,

the parting tool in your pic is I think a manufacturing fault. IMHO the point in a diamond shape parting tool should be in the middle.

Easily rectified, just hold the longer side on the grinding wheel a little longer.

john. B

 

[woodfarmer]

I have found that most newly bought turning tools need to be sharpened/ profiled to one's own fancy, however,

the parting tool in your pic is I think a manufacturing fault. IMHO the point in a diamond shape parting tool should be in the middle.

Easily rectified, just hold the longer side on the grinding wheel a little longer.

john. B

Thanks for the input, but you have misunderstood what has happened. There is no longer side, because the side you see that looks longer is the shorter side of the other side. Ie the edge is skewed across the centre so if the right hand side on top is longer the left hand side of the bottom is longer, or vice versa. At the factory they held one facet flat to the grinding work space, then rolled it over 180 degrees and held the same side facet down. so in effect it is a bit like a miniature skew chisel. I can see why they did it, I myself was puzzling on the best way to hold it straight on the table.

 

[chipmunk]

I wouldn't worry too much about the diamond parting tool grind being dead-on with the facets of the diamond. It is useful if it is square to the major axis though - i.e. the centre line through the tool. Otherwise you'll find it more difficult to cut square tenons.

I have a narrow diamond parting tool (A Robert Sorby actually) where the centre points of the diamonds faces do not line up and I make a best guess at a straight square edge between them and I have not noticed it binding or causing a problem at all.

The gouges are far more forgiving. If you ever get chance to see a Ray Key spindle gouge then you'll never worry about this ever again :wink:

HTH
Jon

 

[woodfarmer]

Thanks chipmunk. I have used the parting tool and it works well so quite happy to keep it as it is. Was just surprised to find that they had made it like that. Also none of the original angles seem to correspond to what I have read, but think much of it depends on the way a particular person handles them.

Just amazed at how much difference three gentle swipes of the grindstone made to the way the 1/2 bowl gauge cut the hard old oak beam.

 

[Robbo3]

I have at last made myself a grinding station. I wanted to just sharpen the new tools I had with the lathe and preserve the original grind from the manufacture to reduce metal removal.

first the 1/2 bowl gauge. I had problems using this on a bit of hard old oak beam, mostly with tearing. Looking carefully at the original grind this was flat cut from teh face of a grinding wheel and not concave from the outer periphery. Actually ALL of the original grinds were done the same way. Flat not hollow ground. This makes a lot of sense to me as I am used to metal turning tools and giving vertical support to the cutting edge is a big thing. about three light wipes rolling it on the platform gave me a shiny surface which when tested both on the oak and a bit of pine cut beautifully. So I also "touched" my 3/8" bowl gauge as well as they both had the same original angle as did my large roughing gauge (45 degrees) none of this is what most books recommend . The 1/2" bowl gauge did not have a even round original grind but as I was able to get an edge in all the important parts I left the original side alone. eventually after a few sharpenings I will get down to that bit.

Apart from needing to make jigs for other angles the basic grind station will do all of the tools I have except my skew chisel.. This came as a surprise because the parting tool is tapered from the middle to each edge and I was wondering how to construct something that would hold it square. Then I realised the the original grind was not square, It had been held down on one face and ground, then rolled over and held down on the same side and ground again. so the tip is slightly skewed. I have used it and it works fine out of the box. If you look closely you can see the tip is not dead central with the centre of the tool. Assuming that is that I can post a picture.

the spindle gauge I haven't sharpened yet as it requires another angle to be set in the grinding station. the thing to note here is that it is lop sided as one side is ground back more than the other. Is this intentional or a manufacturing mistake? I dont want to make it even if it is meant to be lop sided.

Original post above, split to make it easier to answer.

I've had several attempts at composing a reply which just seem to get more & more long winded - so some basic answers which may also benefit others:

There is nothing wrong with a 45 degree bevel on either a bowl gouge or a spindle roughing gouge.

Those that sharpen using a belt or flat disk don't get a hollow grind but the majority of woodturners use a grinder from the front. I wouldn't worry about flat verses hollow grind too much, as long as the tool is sharp, you will find the correct presentation angle to get it to cut.

Most beginners benefit from using a jig to sharpen bowl & spindle gouges. A basic one is fairly easy to make & to use:
- viewtopic.php?t=4443
- viewtopic.php?t=5360
or

Cap'n Eddie Castelin - https://www.youtube.com/watch?v=5i9RDnJHz9g
&

probably the original - the Ellsworth jig (opens as a PDF file which can be saved to your PC)
- http://www2.woodcraft.com/PDF/77B61.pdf

With the handle resting in the socket & the length suitably adjusted you can sharpen parting tools, narrow skews, spindle roughing gouges & bowl gouges that require a straight across grind etc evenly & consistantly.

Lots of good info to help you understand the shape of the tool (bottom of page)
- http://www.peterchild.co.uk/info1/sflute.htm

----
Spindle gouges are normally ground with matching sides (yours just hasn't been ground evenly) but there is nothing wrong with having one side longer than the other. Again, you will adjust to get the tool to cut but it is probably slightly easier if one side mirrors the other.

----
A skew only needs something solid to rest on. If the rest is adjustable, alter the angle to suit & slide the tool from side to side across the front of the wheel. Repeat fot the second side.
If the rest is fixed, use the outermost top edge to slide the tool along whilst your fingers butt up against it to act as a stop.

----
I suspect you will always be unhappy with that particular diamond parting tool & will probably end up grinding the sides flat to make a conventional tool. Perhaps buy another or make your own.

 

[andersonec]

I would imagine your parting tool needs to be square across the end for when you need to cut a small recess or tenon with a flat and square base, if it parts off easier with a skewed edge then maybe two would be the answer.

Andy

 

[Robbo3]

If I understand it correctly the thickest part on one side of the parting tool is not opposite the thickest part of the other. To grind between the two high points, a requirement to stop the tool binding, may result in a square grind but one side will be higher than the other.

I seem to recall an article written by Ian Wilkie (I think) who ground the parting tool like a skew to overcome the ragged edge that the tool sometimes produced - the point being the clean cut & the heel the ragged.
This evolved into a standard parting tool being ground to a slight 'v' shape, using the corner of the wheel to produce two points - probably the precursor to the fluted parting tool.

 

[woodfarmer]

Thanks robbo3 for a detailed and considered reply. I think my original post may have come across more as a complaint than that of an observation. I have looked at the Peter Childs page before and found it very informative., I need to re read it.

What I did was set myself up to grind the tools as they were originally ground. The three that I can now grind with the current jig/angle could have been straight ground using the periphery of the wheel using the same rolling action.. I will try to post a picture of my set up to make it clearer. Later I will include a periphery platform as some tools will be easier to grind that way. The face grinding is probably more for metal lathe tools for use in my Holbrook lathe.

I actually find that the parting tool is much easier to use than I remember it, but I have to say I don't think I have used a wood turning parting tool since before 1960. Oddly enough I seem to get on better with the skew chisel than I remember also. It may well be that reading Keith Rowleys book has helped me, although I seem to be more circumspect using the gouges now which I have used before with complete abandon.