Another Tool Sharpening Jig.

[CHJ]

Objective:
1. To make an alternate style Fingernail & Bowl Gouge grinding Jig. (see previous limited adjustment version)

Reasons:
1. Need of an additional Jig to cover more diverse profiles, and explore different techniques.

Design criteria:
1. To provide the equivalent function of the commercial units.
2. To do it with components/materials readily available in a wood shop.

Materials used:
1. 2 pieces of Beech of 20 X 20 X 300 mm section. Main Rails
2. 2 pieces of Beech of 20 X 20 X 150 mm section. Bench Guides
3. 1 piece of Beech of 45 X 55 X 20 mm section. Tool Clamp
4. 1 piece of Beech of 45 X 55 X 10 mm section. Tool Clamp
5. 1 piece of Beech of 20 X 20 X 150(130 finish) mm section. Adjustable Pivot
6. 1 piece of Beech of 20 X 46 X 120 mm Support Up-stand. See later note.
7. 115 X 68 X 4 mm metal plate. (5mm Birch Ply as alternate)
8. Coach Bolts, Hex headed Bolts, Wing Nuts, Washers and Nuts to suit (6mm.)


Click on images for Larger Files (390 K each) for some reason the drawings do not display well but should be printable to near scale if first saved to local machine (dependant on users software of course).


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___________4mm Aluminium (or 5mm Birch ply).


___________
___________1 piece of Beech of 20 X 20 X 150 (130 finish) mm section. Bolt heads interference fit in recessed holes(10mm for 6mm bolts)


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___________Support Up-stand . 13 mm hole is relieved to 2/3 depth on front and sides to allow pivot swing.
EDIT: I have found that it is better not to have this support stand, forming the socket at the base rail level allows the weight of the tool to be more evenly balanced about the pivot point on smaller grinders.See later post

___________
___________Centre Line of Tool to Centre Line of Ball 150mm.


___________
___________Tool Support Clamp, Drilled to suit Tools, 12.7mm (1/2") is good for 13mm tools, a smaller width Vee Cut would allow wider tool shank size variation.


Some points on construction to note:

The dimensions are not super critical as the final angle of grind is dependant on user setup, the distance between the Pivot Rod Ball Centre and the Gouge Clamp Hole Centre and the Height of the Support Up-stand suit a 6" grinder, I see no reason why they are not viable with an 8" unit due to the adjustments available. The commercial equivalent appears to cover both grinder centre heights.

___________
___________Most of the Bits.

___________
___________Ready to Go.

___________
___________Socket detail.

___________

___________In use, Adjust Support Distance from Grinding Wheel and Pivot Angle to suit profile (or desired profile) of tool.

 

[RPM]

Hi CHJ,

Many thanks for sharing this, It's a great help for a newbie like me (pics too!).


The only problem I have is the socket peg, Did you turn it?
I am afraid I am still on the "rip the wood to pieces stage" at the moment.



Thanks.

 

[CHJ]

Hi CHJ,

Many thanks for sharing this, It's a great help for a newbie like me (pics too!).


The only problem I have is the socket peg, Did you turn it?
I am afraid I am still on the "rip the wood to pieces stage" at the moment.

Thanks.

Yes the Ball was turned, it's size is not critical just as long as the drill size for the socket matches its finished size.

Put suitable piece of wood, (over length) between centres.

Mark overall length, blend point of taper and ball dividing lines with pencil.

With slim parting tool cut two grooves either side of ball lines and one for the top to about half depth as aiming points.

With Spindle Gouge start shaping taper back from the grove to the blend point, working towards the grove, and gently round off top end as far as the bottom of your grove.

(The top grove and radius can wait until ball is formed to improve rigidity)

Do not remove too much wood at this stage to keep it rigid.

Now starting from centre of ball markings, working to left and right to form the ball radius.

When the bulk of the wood is removed, slowly complete the tapered section and the adjacent ball surface until the stem/ball joint is about 1/3rd diameter.

Complete the bottom of the ball as far as you feel confident and the same with the top.

Cut off bottom and top stubs and complete radius with abrasive.

If you are having difficulty in tool control or the wood is flexing enough to make you think disaster is imminent then just resort to some 100 or 120 grit abrasive to finish off. Back it with a 150mm steel rule or similar to work into tight corners and use it like a rasp.

As a new starter here you are in a chicken and egg situation, and IMO the important thing is to make a working tool, which will hopefully assist you to better tool sharpening and control rather than politically correct turning skills.

Hope this helps, a location in your profile may help a local turner give you assistance.

 

[RPM]

Hi CHJ,

Thanks for the swift and very informative reply.
You hit the nail on the head (no pun intended) with the chicken and the egg quote.

It seems impossible to get anywhere without the tools being sharp etc...
I will try the jig build and see how I get on. :wink:

RPM

 

[CHJ]

Hi CHJ,

Thanks for the swift and very informative reply.
You hit the nail on the head (no pun intended) with the chicken and the egg quote.

It seems impossible to get anywhere without the tools being sharp etc...
I will try the jig build and see how I get on. :wink:

RPM

The other one, (see link in first post) may be easier for basic fingernail grinding but does not have so much adjustment capability for other gouges.

I use Both, enables me to save settings for most commonly used tools.

 

[CHJ]

Some reservations about this version of jig.

Because the tool projects a long way forward of the pivot point there is far more contact pressure between the tool and the wheel than with the previous Jig style. With a free cutting wheel like my blue one I find metal removal far to aggressive.

I found that I needed to shorten the support post for one profile, and this has lead me to conclude that the post/support point needs to be much lower, in fact on my small grinder I am currently using it with the pivot socket on the bottom rail, (no post at all) enabling the weight of the tool to be nearer the pivot axis.

 

[treefella83]

cheers mate i'm going to give that a go. :lol:

 

[Philly]

Like it, Chas!
Well done (Also love your website, too!)
Cheers
Philly

 

[santiniuk]

Chas,

After seeing this form of jig in use I'm going to have a crack at making one.

Before I start are there any changes to the design you would recommend ?

Thanks for the plans.

Shaun

 

[CHJ]

......
Before I start are there any changes to the design you would recommend ?
...
Shaun

Don't bother with the vertical post, it throws too much tool weight on the wheel, without it the tool is more balanced about the pivot point, the difference of angles can be accommodated with the existing adjustments, well they do for the bevel angles I use anyway.

 

[santiniuk]

Thanks Chas,

Could be tomorrows project....