Does anyone here use this style of knife grinding jig?

S

setlab

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Apr 11, 2012
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I've been looking at this thing for awhile now and watched some so-so quality YouTube videos on it, it's defiantly is a slick set up. I can see how they grind the straight part of the edge with this jig, but it looks like they grind the rounded tip part of the knife in the same pass without changing anything; is that right? I'm relatively new to grinding knives on the belt grinder and have been using the bubble jig with progressively better successful results but keeping that same grinding angle on the curved tip of the knife is a pain.
 
If you are getting progressively better results, using the Bubble Jig, why stop the progress.

The tip and belly of ever knife is the challenging part. Its because this area is a spiral and does not follow the same angle as the straight area of the blade.

With the Bubble Jig the way to grind this area of a blade is, one, work on the straight area of the blade first. When making passes on the belt, pull the blade straight out across the belt; leave the belly and tip of the blade for last. Once you have the straight section of the blades bevels developed, its much easier to grind the tip and belly.
Whatever technique you are using to grind a blade; its a given that you rotate and twist the blade as it moves along the belly and tip.

If you are considering a sled type jig, as pictured above, the problem becomes more pronounced. In order to do it correctly the sled has to be lifted and twisted as you grind the tip and belly, thats just the way it works.

If I may ask; how many blades have you ground using the Bubble Jig? It takes a few blades to get the technique down, but as you state in your post you are progressing; now is not the time to change course. Give it a little time and you will master the technique.
There is nothing to be learned about grinding by using a sled type jig.

Give me a call on my 800 number if you would like to talk this over.

Fred
 
I have a sled jig similar to this one, and it's designed for the edge of the jig to be a file guide, to butt right against where you want your plunge lines to be. They're not EASY to use, and sometimes they take some tinkering to get things set up the way you need. They can produce a very straight and neat bevel, and are great for scandi grinds. They're clumsy to use, and not great for recurve grinds, or very large blades. Some modification to your grinder and tool rest is necessary for the "travel" of the jig. The one pictured shows the tool rest is angled. The jig that I have has a screw that elevates the angle, and my tool rest is square.

For a blade similar to the one pictured, or any other blade with an upward curve, the only action required is to pull the sled straight across, and pull the knife handle/sled backwards slightly towards your stomach when approaching the point. All in one fluid motion. No lifting, bending or twisting of the sled is necessary. Keep the sled on the tool rest, and pull the handle back towards your body approaching the tip. That's it!
 
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So far I have 3 blades ground with the bubble jig. The goal is to get good at free hand grinding so that's a definite plus to the bubble jig, I have no intentions to quit using it though. That angle iron jig just stuck out, as it looked like a potentially easier and faster way for me to produce a blade, plus I like to tinker around and make new tools to use in my shop. The end goal is to start making knives to sell soon, maybe one or two a week so I can offset some or all of my material and tool expenses; that jig lookes like it fit the bill for doing dummy proof repeatable and even grinds.

On my last bubble jig grind I almost had perfectly matching grinds on either side of the tip but one side was at a noticeable steeper angle then the rest of the bevels, so I'm getting there!
 
I use to have one I made following the example of the CJS video on YouTube. It worked well. Like Josh's jig above, mine had two screws in the bottom to adjust the angle. But the one pictured above looks easy as well.

The learning curve was quicker on this jig than with the Bubble Jig I had but eventually I decided to just bear down and learn how to free hand grind. Looking back now I'm glad I did. It probably won't hurt to experiment with a jig like this, but if you already own a Bubble Jig, you may want to put some more time into learning the ins and outs of it and I'm betting you'll get consistent results.
 
Sled jigs work and have their place in the shop; but if your goal is to expand your grinding skills, the Bubble Jig is the way to go. Every time you grind a blade you learn more about free hand grinding. After all it is free hand, you are just using a different reference point.

Like many hand tools in the shop, there is a learning curve. The same thing applies to the Bubble Jig; but I assure you, you will only get better using it. It was designed with this in mind.

One thing about sled jigs they have very narrow limits; with the Bubble Jig there are no limits. I design blades based on what the jig offers.

Let me know if I can be of any help, Fred
 
That "sled" type jig shoud work very well. When you want to do the opposite side of the blade , the blade doesn't have to be removed from the holder so it is kept in the same alignment. Get it lined up for one side and no change needed for the other. The angle is set by using the long adjustable table. I use two micarta blocks about 3/4" thjick on my set up to hold the blade but that should be super to use as well. Just follow the scribed lines for the blade edge thickness and it will all work out. My table is somne 3 1/2" "L" shaped aluminum. Frank
 
Both of those require you take the blade out of the holder and position it again for the other side. If you have a "sled" type and a tilting table no blade removal is necessary make it up with say 4 bolts - one on each corner and for folder blades use a piece of the same thickness in the opposite end to get it parallel. These can work REALLY well. Frank
 
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