Tru-Grind Jig & SAWG Spacers: Angle Questions

[Eben Fourie]

Greetings,

I am a newbie turner and am getting to grips with sharpening turning tools - finding that round shapes are slightly more complex in terms of angles than bench chisels :-)

I am using the Tru-Grind jig (the older version with 10 notches instead of 4 "teeth" for setting the leg angle), and have also downloaded and made the spacers from the South Auckland Woodturners Guild (SAWG)

Getting some (strange) results, and would appreciate feedback from anyone else familiar with the Tru-Grind jig and SAWG spacers.

Parting tool, scrapers and bowl gouges (with swept back wing type grind) I am all ok with.

Roughing Gouge (Hamlet 3/4)
using the 45-degree spacer, and setting the jig leg to the notch first stop away from parallel
at the bottom of the flue I get a measurement of 50 degrees
at the wing/tip of flue I get a measurement of 35 degrees

when I set the leg parallel to the tool shaft, I end up with wings that are higher than the cutting edge at the bottom of the flue, does not seem right...

http://i303.photobucket.com/albums/nn127/ebfourie/wood_turning/trugrind_jig/roughing-bottom.jpg
http://i303.photobucket.com/albums/nn127/ebfourie/wood_turning/trugrind_jig/roughing-top.jpg
http://i303.photobucket.com/albums/nn127/ebfourie/wood_turning/trugrind_jig/roughing-side.jpg

Spindle Gouge (Hamlet 1/2, roundbar type)
using the 30-degree spacer and setting the jig leg to the second last stop away from parallel (8 on old design or ? 4 for new design)
at the bottom of the flue I get a measurement of 45 degrees
at the wing/tip of flue I get a measurement of 30 degrees

http://i303.photobucket.com/albums/nn127/ebfourie/wood_turning/trugrind_jig/spindle-round-bottom.jpg
http://i303.photobucket.com/albums/nn127/ebfourie/wood_turning/trugrind_jig/spindle-round-top.jpg
http://i303.photobucket.com/albums/nn127/ebfourie/wood_turning/trugrind_jig/spindle-round-side.jpg

Spindle Gouge (???, 1 inch, flatbar type)
using the 30-degree spacer and setting the jig leg to the second last stop away from parallel (10 on old design or ? 5 for new design)
at the bottom of the flue I get a measurement of 50 degrees
at the wing/tip of flue I get a measurement of 30 degrees

http://i303.photobucket.com/albums/nn127/ebfourie/wood_turning/trugrind_jig/spindle_flat_profile.jpg
http://i303.photobucket.com/albums/nn127/ebfourie/wood_turning/trugrind_jig/spindle-flat-bottom.jpg (http://i303.photobucket.com/albums/nn127/ebfourie/wood_turning/trugrind_jig/spindle-flat-bottom.jpg)
http://i303.photobucket.com/albums/nn127/ebfourie/wood_turning/trugrind_jig/spindle-flat-top.jpg
http://i303.photobucket.com/albums/nn127/ebfourie/wood_turning/trugrind_jig/spindle-flat-side.jpg

- Comments / suggestions about the settings / measurements above
- Am I correct in saying that the further away the jig leg is from parallel, you seem to end up with a 15 or more degree difference between the bottom of the flue and the top/wing ?
- Any suggestions / tips on achieving a "flat across" type grind in a roughing gouge, using the Tru-Grind system ?

Hope this makes sense, thanks in advance,
Eben