Making bevels in a knife factory?

aarongough said:
This is an interesting thread, I don't see this type of discussion happening much anywhere, and I for one welcome it very much!
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This is a great discussion for sure. We're always interested in this stuff and like you said aaron, there definitely isn't much discussion/information about mid-tech production methods.

We CNC mill our blades. Although our method is slightly different than others I've seen.
 
I miss read the OP and thought it ask about edge bevels. I have my glasses on now.

The same thing goes for grinding primary bevels as stated for edge bevels. Set up time as well as grinding the bevels themselves is extremely fast. The exact same bevel grinds can be produced over and over without errors. It does not take skilled labor and the technique can be learned in hours. Bubble Jig grinding is faster than any type of free hand grinding, bar none. If you are grinding distal taper in these blades the BJ can be used for this as well.
If your serious about doing quantities of blades, I will send you one of my shop Bubble Jigs to try out and see if it works in your situation. There are half a dozen makers doing this around the country. They are buying extra clamps and two Bubble Jigs to speed production.

PM me or give me a call @ 866-325-2164 if you want to discuss this, Fred
 
I dont know if this is relevant to the wire edm conversation, but I once got a quote to slice up a damascus billet into large blade thickness slices and the quote was something north of $1500. I just assumed that that tech was out of my financial league and never looked into it again. I would be interested if that is not the case.
 
Storm Crow said:
Nathan, I'd love to see this, or a sketch at least.
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Imagine a child's toy truck rolling over a hill. Only the truck has two cam follower bearings and the hill is a cam and it's shaped to create the same movement you'd make with your hands grinding a bevel. It controls elevation and rotation as it is drug back and forth. Depth of cut is a plane.

It's the simplest form of a tracer mechanism (no hydraulic feedback), which is what people did for motion control before CNC.

And for profiling you could make a variation of the inverted pin router used to copy things like furniture and picture frames etc. It has been used in production for 100 years and still is today.

If you're making things in quantity and aren't using CNC, there are mechanisms that people figured out a long time ago. There is no reason they couldn't be applied to a belt grinder. You wouldn't want to fool with it for 10 or 20, but if you're making 100 or a 1000 of a pattern it would be better than making them one at a time freehand.
 
Fred - I still need to watch through your video.

Nathan - Sounds like what I have been thinking about. It's how to design the pattern for the bearings to follow that would angle the blade appropriately to the belt that has me scratching my head the most. I can see it being set up on a little x/y slide table in front of the belt on the angled flat platen so that one simply cranks it in to for the belt to bite the steel, then cranks it over to grind down the length of the blade, with the blade turning to stay in contact. I'm sure calculus or at least trigonometry would be involved in figuring it mathematically, but my poor brain isn't wired that way. The pattern would need to move with the x-axis but be stationary on the y in the way I'm envisioning it.

I'd be starting with pre-cut waterjetted blanks.

I also am thinking that something like this hollow grinding jig:

[video=youtube;08gPbxaXtXo]http://www.youtube.com/watch?v=08gPbxaXtXo&list=PL2cZtXDTod8m1g-BiNGda4b64EqMfn-8T&index=7[/video]

could also be used with a flat platen angled back. It wouldn't need any vertical adjustment for flat grinding.

This looks like it could almost do it, but I'm not sure. He just shows a straight piece of metal.

[video=youtube;p0Jw2-S27vs]http://www.youtube.com/watch?v=p0Jw2-S27vs&list=UUVhMXjmpYE3OAFRppe1sm1g[/video]

But I think I'll go consult with some CNC shops soon.

I'd still love to see more options. Pictures and videos are great. This isn't just jogging the gears in *my* little head, y'know. :)
 
Travis Wuertz' surface grinder is pretty good for the home shop. In huge volumes there may need to be changes. I did some work with his grinder and with just the simple angle set up it cut down a lot of time in starting a grind. I don't know if it's what you're looking for but maybe someone will gain something from reading this.

Here is what I did to set up the angle - using geometry you can calculate the 'triangle' and thickness of the shim:

Hgyhixl.jpg


Setting up a blade can take 30-60 seconds, and grinding is about 30 seconds.:

EUcpHw1.jpg


I remember when I visited his shop earlier in the year he had a modified setup of this where it held two blades, point to point, and there was a mechanism to 'bump' the angle of each blade so it accounts for the change in profile. You'd have to model it out using a CAD program and tailor the modification to a specific model, but if doing a run of 100 or more blades in a small shop, it was really dang nifty. I'm not sure if Travis still does that kind of stuff, but I could always ask.
 
Don - That "bump" was what I was trying to describe in post #13. The knives he was demonstrating with were fairly narrow and straight. I wonder how boogery it would be to set up for something with a bigger, more gradual belly on it.

30 seconds of grinding and then heat treatment? Sounds great! With your (beautiful!) kitchen knives, you're likely using thinner stock than I will for my military-oriented blades, but still. That is impressive.

Yes, things like this are exactly what I'm curious about. Setups that make low-level production feasible to a small shop, whether that's grinding jigs or farming it out to a CNC shop.
 
I recall talking with Bob Egnath once and he mentioned he was running a large horse power belt grinder. Maybe a 3horse or more. He was grinding blade blanks for commercial sales and in bulk, freehand. Maybe just amp up your grinder? Some of the blades he was doing were similar size to many of my 8-10in blades camp knives and he said he was around 5-10 minutes per blade! I run my Bader BIII fast but I can't hit those numbers.
 
Storm Crow said:
Nathan - Sounds like what I have been thinking about. It's how to design the pattern for the bearings to follow that would angle the blade appropriately to the belt that has me scratching my head the most.
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It sounds complicated but I really don't think it is. You could develop the profile on paper by starting with your blade blank against a reference point and marking the location of both cam followers. Then moving the blade, keeping the "grind" location the same relative to that reference point and marking those locations again. Repeat the process, moving the blade up and down and rotating as required as it is pulled to the side until you have generated a point set. Connect the dots and you'd have your cam. Flip it over for left and right.

I've used this kind of approach before in a somewhat different application (generating an involute form from a rotating piece instead of a sliding piece) and it worked pretty well.


Now that I'm thinking about it, I think I'll build one when I get a chance.
 
Storm Crow said:
Don - That "bump" was what I was trying to describe in post #13. The knives he was demonstrating with were fairly narrow and straight. I wonder how boogery it would be to set up for something with a bigger, more gradual belly on it.

30 seconds of grinding and then heat treatment? Sounds great! With your (beautiful!) kitchen knives, you're likely using thinner stock than I will for my military-oriented blades, but still. That is impressive.

Yes, things like this are exactly what I'm curious about. Setups that make low-level production feasible to a small shop, whether that's grinding jigs or farming it out to a CNC shop.
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They were ground post-HT, on blanks that were 0.180" thick. With thicker blades, you really wouldn't see much of an increase in time, maybe 10 seconds or so. Most of the time is involved with stopping and changing out the blades :)
 
Bill - I've seen videos of Ray Ennis grinding knives on a belt grinder that looks like it'd eat your arm up to the elbow if you slipped! Sounds similar. But part of what I'm trying to sort out in my mind is a way of allowing for the expansion beyond being a one-man shop, with the possibility of having workers who are not necessarily skilled knife grinders in their own right to be able to consistently create a quality bevel. I don't know if I'll ever grow beyond a one-man shop, but it'd be nice to be moving that much volume. :)

Nathan - Was thinking of something along those lines for tracing out a pattern, but your method sounds more... methodical. :D

Don - Oh yeah, forgot about kitchen knives often being pre-heat treated before grinding. Makes sense.
 
Don Nguyen said:
Travis Wuertz' surface grinder is pretty good for the home shop. In huge volumes there may need to be changes. I did some work with his grinder and with just the simple angle set up it cut down a lot of time in starting a grind. I don't know if it's what you're looking for but maybe someone will gain something from reading this.

Here is what I did to set up the angle - using geometry you can calculate the 'triangle' and thickness of the shim:

Hgyhixl.jpg


Setting up a blade can take 30-60 seconds, and grinding is about 30 seconds.:

EUcpHw1.jpg


I remember when I visited his shop earlier in the year he had a modified setup of this where it held two blades, point to point, and there was a mechanism to 'bump' the angle of each blade so it accounts for the change in profile. You'd have to model it out using a CAD program and tailor the modification to a specific model, but if doing a run of 100 or more blades in a small shop, it was really dang nifty. I'm not sure if Travis still does that kind of stuff, but I could always ask.
Click to expand...

That's pretty much a Sine bar and gauge block set-up. Nice work
 
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