Flat grinding with a BUBBLE JIG

[crazyhorse]

Fred,
Being a new member I was unable to see your original pictures. Would it be possible to have them reposted. Sorry for the inconvience. But thanks for the trouble. I need all the help i can get.

Daniel

[beachcaster]

Fred,
Being a new member I was unable to see your original pictures. Would it be possible to have them reposted. Sorry for the inconvience. But thanks for the trouble. I need all the help i can get.

Daniel

YES ! Fred another request to see your original pics

many thanks


Barry

[jerbal]

could you put a little swivel in it to be able to grind the other side without taking it off?

You'd have to be able to lock it or the swivel would let it change angle to the belt face.

[MushiSushi]

could you put a little swivel in it to be able to grin the other side without taking it off?

you just release a screw and turn it round, no angle change

[n0rth3rnlight]

i will make one of these this weekend.
/M

I just feel that it gives you one more thing to focus on. It appears you have to concentrate on that bubble in order to get you angle right and that seems a bit tedious

When I came up against the problem of flat grinding and keeping your angles exact, I made a jig that had a blade clamp that moved up and down a round bar held in a frame (I need to make another one!!) how close you clamped the frame to the grinder determined your angle and you could work all day long and never lose that angle. In theory you would have been able to grind a hundred blades each with exactly the same bevels and no little bubble to concentrate on. And because the clamp rotated on the bar, you were able to take the blade away from the grinder and look at your work and then put it back knowing that your angle would be perfect every time.

lets see if a sketch helps:

[Sparrowhawk]

Fred, original pictures please as I have no idea what you're talking about and desperately need a useable jig!

[Benji]

I've been toying with the idea of getting one of these for a while, plenty of video showing the thing in action on Fred's website: http://bubblejig.com. Maybe Fred could do BB a group buy if there's interest

[Stew]

I've been toying with the idea of getting one of these for a while, plenty of video showing the thing in action on Fred's website: http://bubblejig.com. Maybe Fred could do BB a group buy if there's interest

Why do a group buy? For a discount? If you take into account the onward postage from the UK to each person and possible import tax charge, there's little point.

Fred's prices are very reasonable and his service is excellent. He stands by his product and stands by his customers.

[Greenbeast]

What i'd like is a set of those angled blocks! i made one a while back but don't know how accurate it was, these seem handy little things.

[Fred Rowe]

i will make one of these this weekend.
/M

The greatest advantage of my invention is its versatility. Grinding with this system gives total free hand control but with repeatable accuracy. All sled style jigs are controlled by their contact with the work rest. This makes it difficult to grind along the blades tip and radii because the angle control is dictated by the jigs contact with the work rest. Using the bubble as a reference its quite easy to make the required twist and lift of the hand that is needed to grind along the radii and tip of a blade. Blades with four surface grinds, like daggers can be easily accomplished with but a little practice with this system. The system is quite simple to use and quite accurate to boot.

Fred, original pictures please as I have no idea what you're talking about and desperately need a useable jig!

Sorry, the original pics have gone with a hard drive change.

I've been toying with the idea of getting one of these for a while, plenty of video showing the thing in action on Fred's website: http://bubblejig.com. Maybe Fred could do BB a group buy if there's interest

I had considered a group buy but I decided instead to offer free world wide shipping. Thats a 16.95 savings on the complete kit.

Why do a group buy? For a discount? If you take into account the onward postage from the UK to each person and possible import tax charge, there's little point.

Fred's prices are very reasonable and his service is excellent. He stands by his product and stands by his customers.

What i'd like is a set of those angled blocks! i made one a while back but don't know how accurate it was, these seem handy little things.

The degree wedges can be cut on a miter saw. They are quite accurate.

There is no risk to buying this jig; your money back if you are not completely impressed and satisfied with the product. We have sold over 600 of these without a single return.

Regards, Fred

[rojaz]

Another recommendation for Freds bubble jig.

From the start of making knives, and given obvious the lack of confidence and skill - I made and used dozens of jigs for helping with the grinding. They all have their limitations. For example the one shown above will be fine for a straight line, but considering the curved blade, it will never be able to produce the grind shape required without some manual control (ie taking it off the jig) to follow the curve and get a distal taper toward the tip.

Grinding a blade requires hundreds of subtle angle and pressure changes that can only come with free-holding the blade and it requires practice and experience until the action becomes second nature. The grind bevel has multiple aspects that have to be monitored during the process - including the thickness to the edge and tip, proximity to the spine, plunge neatness and symmetry, flatness etc.

There is no quick fix and it is difficult. There will be many wasted pieces and this is why lots of people become frustrated and give up.

I am not an expert and this is my opinion. What work for me might not be for everyone, but my advice would be to forget the jigs, use the time saved constructing them to concentrate on practicing freehand grinding. Use wood the same dimensions as your knife and play with the grinding. This way you don't worry about wasting tool steel and can Just have fun watching how your different holds, pressure angle changes and movements create subtle effects on the grinds. You will learn the best way for you to brace the knife and how careful you need to be to keep that line steady.

Freds bubble jig is used freehand and helps with the angle observation as you are learning. With experience you will make these calculations yourself, but at the start it is excellent.

[Sparrowhawk]

I just feel that it gives you one more thing to focus on. It appears you have to concentrate on that bubble in order to get you angle right and that seems a bit tedious

When I came up against the problem of flat grinding and keeping your angles exact, I made a jig that had a blade clamp that moved up and down a round bar held in a frame (I need to make another one!!) how close you clamped the frame to the grinder determined your angle and you could work all day long and never lose that angle. In theory you would have been able to grind a hundred blades each with exactly the same bevels and no little bubble to concentrate on. And because the clamp rotated on the bar, you were able to take the blade away from the grinder and look at your work and then put it back knowing that your angle would be perfect every time.

lets see if a sketch helps:

How do you grind the tip of the blade? Surely if you keep the blade perpendicular to the grinder the tip of the blade will be ground at a different angle than the flat section.

[MushiSushi]

How do you grind the tip of the blade? Surely if you keep the blade perpendicular to the grinder the tip of the blade will be ground at a different angle than the flat section.

There is a fractional change in angle as you get towards the tip, and I mean fractional. Can you notice it on this blade ground using that jig?

[Sparrowhawk]

There is a fractional change in angle as you get towards the tip, and I mean fractional. Can you notice it on this blade ground using that jig?

So what do you do? Just lean the blade in at a shallower angle? Or do you adjust the knife on it's mountings?

[MushiSushi]

Just lean in a little bit more. Depending upon the length of the arm on your jig (the longer the better) you're probably not even changing the angle by a whole degree. It's not something discernable to the naked eye. You'd probably have to have a digital angle finder to hand to even be able to tell that the angle is fractionally different. Alternatively, tilt the blade a little in the jig so that the bottom of the edge and the tip are parrallel, that way you just have a fractionally shallower angle on the belly of the blade.