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Sawdust Maker
9th August 2009, 10:28 PM
Was sharpening up my Hughies today after finally getting around to putting handles on the newest one.

It dawned on me to wonder what the best grind angle was? My little Hughie was originally ground at about 45 degrees. I thought this might have been a tad aggressive. I note that some of the articles on the www suggest 45 degrees.

So what angles does the brains trust use? And any special shapes?

Skew ChiDAMN!!
9th August 2009, 10:44 PM
For a square-tipped oland bit, 45° is probably as good as anything.

However, my favourite profile is a rounded, semi-circular tip with both sides sharpened back for about as far as the tip is wide. Grinding this at 45° results in the two "side bevels" meeting at the bottom surface, making the tip thinner.

So I sharpen these at somewhere around 70°-80° so that I still have a short bit of "flat" on the bottom between the two side profiles. (If you understand what I mean?)

It's still an aggressive tool... I plunge cut with it and can then sweep left or right, taking out a 6mm(ish) swathe with a 5mm tool. :2tsup:

joe greiner
9th August 2009, 11:31 PM
45 degrees seems too aggressive to me. And both sides would meet at about half the thickness. I use rounded end, with about 10-15 degrees clearance angle on the end and both sides, slightly farther back on the left side of the cutter for hollowing.

Cheers,
Joe

hughie
9th August 2009, 11:36 PM
Yep thats about it for me as well, although I give the side a bit of a longer grind, say 10mm as opposed to 6mm for Skew. I also give the side grind only a small relief angle, say around 5-7'. Which makes it around 85ish, I find this does me fine.

But it does depend on what diameter your turning. If like Skew your turning a goblet then you must increase the angle other wise you wont get any clearance on such small dia.

TTIT
9th August 2009, 11:46 PM
I reckon mine would be about the same angles as Hughies but I don't come back on the side as far - but I have both sides even 'cos I cut both ways with it. :;

kdm
10th August 2009, 08:49 AM
It's early days for me but what I currently have for hollowing small boxes etc is a 45° angle at the tip fading on the sides like a fingernail grind on a gouge. I'm sharpening the tip by putting the whole tool in a Tru-Grind jig.

hughie
10th August 2009, 09:06 AM
I'm sharpening the tip by putting the whole tool in a Tru-Grind jig.[/QUOTE]

I generally remove the tip and set the standard grinder rest to the required angle and grind by hand. Once you get the hang of it, it will take very little time and effort

If you have a favourite grind, sharpen both ends and just swing it around when required, this will speed up things considerably.

TTIT
10th August 2009, 09:36 AM
I sharpen my Olands in a jig too. I find it quicker to clamp the whole chisel into the jig than it is to remove the tip and use the rest. Also removes less meat which is good when you are using the butt-ends of old drill bits which aren't all that long to begin with :B For the oland that sticks out the side at an angle, I often touch it up with a diamond stone until it needs a good grinding and then just drop it in the straight shaft to use the jig.

oldiephred
10th August 2009, 09:39 AM
I would appreciate some help. I use the oland tool almost exclusively and have no trouble as long as it is sharp. I never have been concerned about the angle. My question: How can the angle of grind affect the cut as long as there is clearance on the under side for the workpiece to clear the tool? The cutting is done by the top, leading edge of the tool so why does it matter how much the angle is?

NeilS
10th August 2009, 11:16 AM
The cutting is done by the top, leading edge of the tool so why does it matter how much the angle is?

Lower angles (ie the included angle (http://books.google.com.au/books?id=CtkWaJw5iXkC&pg=PA16&lpg=PA16&dq=included+angles+blade&source=bl&ots=TzmLUJE4WJ&sig=L2bvjjczxExqCZGIRRv1AjRXlrc&hl=en&ei=lV5_Sr-HNMmSkQX4vNHxAg&sa=X&oi=book_result&ct=result&resnum=3#v=onepage&q=included%20angles%20blade&f=false)) tend to cut/slice, higher angles tend to scrape. The latter often employs a raised micro burr that, ironically, cuts like a very low included angle edge which is fragile and has to be refreshed frequently.

Neil