Sharpening Jig, take 2

[Fumbler]

Following on from the sharpening set up, which works fine for roughing and spindle gouges with regular grinds, but I found I need to regrind for swept back wings and detail gouges. So saw this jig online, downloaded the plan, and although the measurements written didn't match (exactly) the plan when printed, a little adjustment with the photocopier, ie copy by 103% and she was apples.

I had some spare 6mm project ply (the one with the nice face), and more of the left over $2.00 12mm ply bunnings offcuts. And for the pivot, some left over Jarrah, jointed and thicknesses to 12mm.

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Pictured with an un-handled 1/2 spindle gouge. Want to make another fancy handle, as opposed to my last one which was straight Jarrah and although still very nice, it is quite bland in comparison to some of my others.

[Skew ChiDAMN!!]

Looks good.

I'm not too sure I like the way the head of the bolt is used to hold the tool in position; but that's really only a minor nit-pick.

(I prefer if it applied the pressure to a separate brass plate, to prevent any possible damage to the tool from over-tightening. However, even in the commercial ones at best there's just a pivoting iron washer.)

[Fumbler]

Looks good.

I'm not too sure I like the way the head of the bolt is used to hold the tool in position; but that's really only a minor nit-pick.

(I prefer if it applied the pressure to a separate brass plate, to prevent any possible damage to the tool from over-tightening. However, even in the commercial ones at best there's just a pivoting iron washer.)

do you mean damage in via flex to the tool shaft, or scuffing/scratching from the bolt head as it tightens down? I have 2 things in mind as they both drew my attention, 1. A support at same height as the bottom of the hole, and 2. to prevent scuffing, a self adhesive rubber pad or the loop side of hook & loop self adhesive tab.

[Paul39]

I think any scuffing that happens will not make any practical difference as it is far down the shaft. If you are using a swept back grind the cutting part will be below any scuffing. The fixture will be torn apart before enough pressure is put on the tool shaft to bend it.

Very nice shop made jig.

[Fumbler]

I think any scuffing that happens will not make any practical difference as it is far down the shaft. If you are using a swept back grind the cutting part will be below any scuffing. The fixture will be torn apart before enough pressure is put on the tool shaft to bend it.

Very nice shop made jig.

after my reply to Skew, I did think there wouldn't really be that much pressure over a 2inch span to create flex in the HSS steel, and I know what he means, no one likes tools that are scuffed unnecessarily.

and thank you by the way.

[NeilS]

The screw attachment that makes contact with the top of the gouge and presses down on the upper edges of the flute is the most critical component in getting a repeatable grind on this style of jig. IME, there are two critical factors:


That contact surface MUST maintain its squareness to the screw shaft. If not, the grinds will vary a bit each time. Result: one wing or the other will be ground but not the other. The more out of square the more unpredictable this will be.
That contact surface MUST also rotate freely on the screw shaft. If not, the gouge will be moved by varying amounts from the set projection each time the screw is tightened to secure the gouge. Result: an unpredictable grind area between edge and heel. eg, only the previous edge will be reground and not the entire bevel or just the heel.

Of course, the screw shaft must run true and not have any play.

If the contact area rotates freely on the screw shaft it will not mark your tool, if that is important to you.

Other jig designs, like those that have a cantilevered plate that pushes down on the tool, do not have these but other factors to take into account.

[Fumbler]

I'm new to the sharpening gig, and will practice on some el'cheapo $39 tool set i bought many years ago from Bunnings (when they actually sold more than just screwdrivers and outdoor settings). But as the screw down clamp is zinc plated, it will probably scuff before the tool does.

I bought some 1/8" 20mm flat bar HSS for a new thin parting tool and went to cut a tang and hit it with the hacksaw with a cobalt blade, only the blade (which slices through stainless like a knife through butter) didn't leave a mark, so i doubt that HSS turning tools will get scratched.

[Skew ChiDAMN!!]

NeilS raises a couple of legitimate concerns (the 2nd is the bigger, IMHO) but with a bit of use you'll soon find out whether your jig has these problems or not.

Even if it does, there's a simple - if slightly klugey - fix... grab a bit of thin brass plate (or iron if that's all you have) about 4mm x 1" x 2" and slip that in from the side of the jig, between the tool and the screw, before tightening. (I've also seen these plates made from a bit of ply, but they're best considered as sacrificial.)

[Fumbler]

NeilS raises a couple of legitimate concerns (the 2nd is the bigger, IMHO) but with a bit of use you'll soon find out whether your jig has these problems or not.

Even if it does, there's a simple - if slightly klugey - fix... grab a bit of thin brass plate (or iron if that's all you have) about 4mm x 1" x 2" and slip that in from the side of the jig, between the tool and the screw, before tightening. (I've also seen these plates made from a bit of ply, but they're best considered as sacrificial.)

As per this pic, I have put self adhesive Velcro pad to allow free rotation and once locked down 1. Doesn't damage the tool or 2. Doesn't allow any rotation/movement of the tool whilst in the holder. As you can see the furniture bolt I have used is not fully threaded so to put anything else under it I would need to thread the entire length of the bolt to give me clearance. Not a drama, but I will have to buy a die set as I only have taps......

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