ice auger blades won't cut

[Rcdizy]

I had these ice knives professionally sharpened and all they do is spin now and will not cut more that a concave small bowl out of the ice.. I have a dull unsharpened one sitting on top for comparison. Some how Ive lost the relief out of the geometry?

 

[4ssss]

I have the machine and fixtures to sharpen blades, and I do them for bait shops in the area. If you're talking about that little concave relief on the face of the really dull blade, that's automatically put in by the wheel, and the bigger the wheel, the less you get. I also never put the chip breakers back into them once they're sharpened. If the bottom of the blade has been touched, ground, honed, stoned, and anything I may have missed (the side with the writing on them) you can throw them away.

 

[Superburban]

I have the machine and fixtures to sharpen blades, and I do them for bait shops in the area. If you're talking about that little concave relief on the face of the really dull blade, that's automatically put in by the wheel, and the bigger the wheel, the less you get. I also never put the chip breakers back into them once they're sharpened. If the bottom of the blade has been touched, ground, honed, stoned, and anything I may have missed (the side with the writing on them) you can throw them away.

So what is wrong with Rcdizy's? From the pics, I'm not seeing anything that would make his not cut.

 

[P. Waller]

The rhombus angle is incorrect, in order to bore through ice this angle must be less then 7.1325 Degrees, 7.1310 degrees will cause all manner of problems.

While hundreds of years of ice drilling has proven that 7.1310 degree angles will work a tool rhombus angle of 7.1325 degrees is far more effecient.

 

[Superburban]

Silly me, I was thinking they used a metric blade sharpener.

I'll try to remember to check the angles on my Jiffy auger. But its so old, it was likely last sharpened before Mr Rhombus got into the ice drill business.

Just kidding. But I would have thought the rake, and relief angles would be whats important, and from the pics, they look like they should cut something. I have never used my jiffy (came free with a bunch of other stuff), I want to take a look at it tomorrow.


Thanks.

 

[4ssss]

It doesn't take much of anything to make an ice blade junk. A few years back Strikemaster was using Chinese blades instead of the Swedish blades they were using. Those were junk right off the pile. I have no clue what a rhombus angle is, and apparently the good people that make the machine don't think it's a big deal, or they would have calibrated the fixtures, and they've been making this machine for 30 years. I've been sharpening blades for 5 years now and I've never had one come back because it didn't cut well. I have to follow the angle that is there to begin with, and if that was screwed up from the start, you're just multiplying the screw up. I can't see what's going on with that blade because I don't have it in front of me. It may have been altered, maybe they were ground by hand, or it just may be that too much has been ground. You can't see what's going on down that hole. You need to complain to the guy that sharpened them for you, because you're not going to sharpen them by yourself. Now I'm heading out to walk on the water, hope they're biting.

 

[fkrel]

I have a magnum 3 that I have had for years and it still cuts great I sharpen the bade with my belt and disc combo and use the belt last year I had a problem with mine cutting and I sharpened it a second time, I have a lake just a couple of miles down the road so I went to test it and it would only cut a dish in the ice like yours unless I put all my weight in it and force it to cut so looking at the blade end I found the center point that I thought was there to keep the auger from walking around had an edge on it that was very dull I used my hand grinder and sharpened it and then went to the lake and it cut like it was new. Check your point in the center of your auger.

 

[middle.road]

Interesting read, I wouldn't have thought that there was that much detail to sharpening them.
Then there is the bit about cold, ice, wind, snow..... Testing sounds like a pain.

 

[P. Waller]

I have no clue what a rhombus angle is,

It was a joke on my part.
A rhombus is a geometric shape with 4 sides of equal length yet unequal angles.

 

[Superburban]

It was a joke on my part.
A rhombus is a geometric shape with 4 sides of equal length yet unequal angles.

You had me. If you would have left off a few decimal points, You may have had me better. I did spend some time trying to visualize how a rhombus would apply to the side profile of the blade. I waited to take a look at my old Jiffy, but it does not even have removable blades.

So Now I'm back to wondering how Rcdizzy's blades were sharpened wrong. Inquiring minds want to know.

looking at the blade end I found the center point that I thought was there to keep the auger from walking around had an edge on it that was very dull I used my hand grinder and sharpened it and then went to the lake and it cut like it was new. Check your point in the center of your auger.

I think you are on to something there. To me, it looks like there will be a bunch of ice uncut in the center. Looking through the internet, it looks like most of Moras do not have the center point.

 

[savarin]

I know nothing about ice augers but have done a fair number of large ice carvings.
The chisels I used had to be ultra sharp and the back edge had to be dead flat with no angle else they just skidded.
I would check if the edge of the blade against the ice has been ground away from flat I would suspect that this is what is wrong. In other words you have a flat edge on the ice rather than a sharp edge.
Your blade in the second photo looks as if the edge of the blade has been stoned on its back side to remove the grinding flash producing a tiny flat edge.
I could be totally wrong here, Just my 2c

 

[Rcdizy]

The sharpening guy is a fully equipped shop that sharpens everything, including endmills. He thinks that the circled area needed to be taken down , so I let him sand a few thou. off. He compared it to the circled area on the saw blade picture, and said it was just to control how much it can cut.

I would assume he understands relief angles, and geometry....?
I will try it and see,.
I figure it will get one of the following results.

1. still wont cut.
2. will cut good but wont like "finishing the last part of the hole" and want to corkscrew into the ice at the end of the drilling
3. will work good now?


At the end of the day worst case they are garbage.

The centre point is sharp, there has been no stoning of the bottom side....... new replacements are all Chinese unfortunately, the auger itself isn't out of angle alignment, the dull blades work fine.

 

[Superburban]

It has been an interesting thread. Hard to get a good idea of the three dimensions from a pic, But I can see what your sharpening guy is saying.

If By Chance they do not cut, and you think of it, take a pic of the hole for us.

 

[jim18655]

I can't tell how much relief angle is on the blade mounting but could the mounting bolts be rubbing on the ice? They look like they're sticking below the blade. Maybe missing a washer on the top?

 

[mcostello]

Why not take a turn or two around the ice with Your tool and see where it is cut after putting a coat of food coloring on the ice to highlight where it is not cutting? Pictures here help.

 

[Liljoebrshooter]

In the 3rd pic in the first set, that edge doesn't look sharp at all. You can see the edge looks rounded.
I would think you would want an edge like on a plane iron. Lapping the back to be perfectly flat to remove the burr from sharpening. That edge should probably be able to shave.

 

[P. Waller]

I use a Solstice 2 MK 3 121147 model ice auger, the blades have a .700 Degree positive rake angle and work a charm in Summer ice, often entirely to quickly.

There is some evidence that ice at 65 Degrees F is rather soft and easy to drill, I do not believe this.

 

[Superburban]

It definitely is soft at 65. I was able to scoop some up with a cup. Similar consistency as the beer I was drinking. I think it has something to do with the rhombus effect.

Maybe that could be a solution for RCdizzy, bring along a torch set to warm up the ice.