jigs to help maintains consistent angle when sharpening or beveling...

V

Vulcanite

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Jan 16, 2009
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This is a "monitor arm", this one to hold a lap top. There are other similar ones to hold computer monitors or big flat screen TVs. Some of them mount to a bench, some to a wall. Some even have three arms. The problem is that they cost at least $100.

I was thinking of something like this for a while that would hold a knife w/ a clamp or magnet and would maintain a perfectly consistent angle when using my belt sharpener, an upside down Harbor Freight 1x30. I can't remember if I have seen pictures of sharpeners with arms like this or if I just imagined it.

Anyway, is there anything like this for sale reasobnable or is there any way I might could put something together w/o welding w/ various hardware? Maybe some square tubing and bolts & lock nuts or something. Or any similar mechanisms that I could mount adapt for this?

Thx
 
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Try Fred Rowes bubble jig, or a device called a sled jig. There's all kinds of threads on both devices
 
strider214 said:
Sorry, but I can't wrap my mind around how it would be of use.
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Here is another picture, though one with three segments might be better:
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Basically, you would mount that in front of the belt sharpener, maybe on a 2x4 that can be tilted w/ a screw jack, remove the plate that holds the back of the TV and replace w/ some way to hold the blade and then sort of do free hand passes across the belt but w/ that arm moving w/ you and holding the blade at same angle.

Is probably too complicated. I should probably just make an double rest that would straddle either side of the belt that could be adjusted to different angles and secured w/ wingnuts.
 
I looked up the bubble "jig." Very interesteing. I should get one at some point to develop some free hand grinding skills.

I found this a thread here about jigs. Would this be a sled jig?
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The problem w/ this type of a jig, it seems to me, is that it can only be used to easily make a straight edged knife w/ no belly. Here is the thread of the pic above:
http://www.bladeforums.com/forums/s...one-here-use-this-style-of-knife-grinding-jig

THe OP states:
"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?

It seems like one would have to sort of tilt it up when grinding the tip area to keep the edge referenced to the belt...

I'll probably just make one like this,
IMG_5610.jpg

though a cruder version of the concept for the belt sharpener. That is the straddling rest I was talking about, Functionally similar to the hollow grinding jig Stacey posted but narrow rests straddling the belt rather than a broad work rest so you can hold the handle.
 
Try the sled jig. It's dead simple. Ignore anyone that says you need to lift, tweak, raise etc. The sled stays on the tool rest and to grind an upward curve, the only motion you need to make is to pull the handle end backwards toward your body. Pull the sled horizontally across the tool rest and towards the tip, pull the handle back. That's it.
 
The problem with the articulating arm is that any side to side motion will inherently also change the distance from the belt. Also, there is no way you can make this operate smooth and friction free, you would end up fighting the arm. Sled jigs are used by many and seem to have a place but I never tried one. I do have the bubble jig and I think it is as close to free hand (actually is free hand) as you can get without a fixture. It allows you to develop that skill so eventually you learn to work unaided.
 
Josh Mason said:
Try the sled jig. It's dead simple. Ignore anyone that says you need to lift, tweak, raise etc. The sled stays on the tool rest and to grind an upward curve, the only motion you need to make is to pull the handle end backwards toward your body. Pull the sled horizontally across the tool rest and towards the tip, pull the handle back. That's it.
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Okay, thx for clearing that up.

I guess the only theoretical draw back to it would be that you would be doing one bevel entirely, and then the other.
 
Vulcanite said:
Okay, thx for clearing that up.

I guess the only theoretical draw back to it would be that you would be doing one bevel entirely, and then the other.
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I'm one of those people that Josh says you should ignore.

Sled jigs work just fine if the goal is to grind blades where you want the grind line to follow the edge profile . They do this quite well. If you are grinding a blade with full distal taper, you don't want this to happen. It alters the distal taper at the tip, causing the angle to pinch in.

They are great for scandi grinds without distal taper. They do this well.

If you are looking to make big bowies or fighters with distal taper, find another way.

Fred
 
I finished building a adjustable table for a sled jig, and love it :). As long as you end with the tip still on the belt it will not round it. The only challenge with mine so far is setting it even on both sides so the plunges line up.
 
I've ground full flat ground knives with distal taper on a sled jig. No big deal.

Good luck man.
 
For the the little sharpening belt grinder I will make a little wooden tiltable rest for the knives to lay on as I draw the edge across the belt.

For the 2x42 grinder, I worked out a design to make sort of similar to the one narrow one pictured above that has little legs straddling the belt.

My question to you all is:
can I make it out of a slab of paper micarta I got from TX Knifemaker? If the blade is two or three hundred degrees it wont burn the micarta will it? It will be made out of four pieces. Can I bond micarta pieces together with wood glue?

Otherwise, I will have to grind out the pieces and take them somewhere to be welded togther and I don't know if they could guarantee it to all be perfectly flush and square...
 
Nick Wheeler made a nice jig that I may try some day. I don't know where the link is at the moment, but it solves many of the issues mentioned. I should go look for it and save the picture.
 
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