GRINDING

[Pipster]

Sorry everyone but I'm sure you are all fed up with newbies asking about grinding ... BUT
I have been looking at some jigs available and realised that they only hold the tool at a fixed angle..that is to say, they stop you from pivoting the tool in the vertical plain (back hand up or down). Well I have made one very easily that does this and I dont think there is any need for anyone to spend much. However.. there is no jig that controls the amount of pressure you put in the stone (forwards and backwards) so.. even when using a jig..how do you control the amount forward/ backward force that inevitable results in a faceted surface if inconsistent ??? I can get the bevel constant..NO PROBLEM.. but it is faceted and uneven .

Can I just add that i am very proficient in knife blade/ chisel/ plane blade sharpening so i do understand all about angles and honing etc and I can sharpen a knife until you can shave with it ... so I am not just some beginner who it attacking a grinding wheel with free abandon !

 

[CHJ]

I know of no jig that is used in a fashion that allows you to pivot the tool fore and aft in the jig whilst you are grinding.
Once the desired tool approach angle is set the jig is locked and shaping done with lateral swing only.

If you are getting facets on the bevel then you are not smooth enough in your pivoting of the jig.
Tool contact pressure is down to operator, if you jig is set up correctly then the tool/jig balance should be neutral so that only the lightest finger pressure is all that is needed to kiss the tool against the wheel.

 

[Pipster]

I know of no jig that is used in a fashion that allows you to pivot the tool fore and aft in the jig whilst you are grinding.
Once the desired tool approach angle is set the jig is locked and shaping done with lateral swing only.

If you are getting facets on the bevel then you are not smooth enough in your pivoting of the jig.
Tool contact pressure is down to operator, if you jig is set up correctly then the tool/jig balance should be neutral so that only the lightest finger pressure is all that is needed to kiss the tool against the wheel.

so the jigs actually STOP you from pushing on the stone ?
the videos are very misleading then . they all look like they hold it at and angle and allow you to swivel sideways and rotate but not stop you from putting pressure on the grind stone.. the amount of pressure on the stone depends on how much the tool needs to be ground so how can the jig or the operator know that untill they start the grind? at which point it is too late ?

Im not being argumentative ..i just cant see how

 

[CHJ]

As I said , Tool contact pressure is down to operator, no lathe tool jig is going to remove operator skill.

You should NEVER need to apply any significant pressure to a grinding wheel, if the wheel is sharp and cutting correctly then the lightest kiss against the abrasive should remove metal fast enough, applying pressure only generates unecessary and unwanted heat.

 

[cambournepete]

I know of no jig that is used in a fashion that allows you to pivot the tool fore and aft in the jig whilst you are grinding.

The Tormek bowl gouge jig lets you move the gouge in and out...

 

[CHJ]

I know of no jig that is used in a fashion that allows you to pivot the tool fore and aft in the jig whilst you are grinding.

The Tormek bowl gouge jig lets you move the gouge in and out...

Yes it does, all jigs do to allow tool contact with the wheel/belt but you do not pivot about the Jig adjusting joint.
You pivot about the location base until the tool kisses the wheel/belt with the lightest touches.
The only fore and aft movement in that case is either to touch the wheel/belt or not touch it, no way should it cause facets to be formed on the bevel.

For skews a straight contact with the wheel/belt produces one continuous facet across the whole face, with gouges, one continuous lateral sweep produces a continuous curve with no facets, if you are producing facets then you are not sweeping the tool smoothly or pressing excessively hard at one or more points.

 

[cambournepete]

Sorry Chas, I didn't explain clearly (well at all really ), so I'll try again.

Here's a picture of the Tormek SVD-180:

As you say you pivot the jig holding the tool forward about the horizontal bar so that the tool touches the grinding wheel and then swing it side-to-side smoothly to get the lovely face they show.
If you loosen the collar on the left (using the big black knob bottom left) then you can move the tool forward to grind away the heel of the face.

This jig works equally well on normal grinders by the way.

 

[CHJ]

Yes I understand the principle Pete.
I use it on various home made versions using the same principle that the Tormek uses.
I even did a Mag. review of the Tormek for turning tools.