Belt Sander Sharpening Problems/Solutions

B

BladesB4Firearms

Joined
Oct 13, 2013
Messages
182
Hello, everyone. I've been belt sander sharpening for the better part of 2 years now and there are somethings I have had problems with and woulkd like to speculate with you guys on possible solutions :)

Problem #1
Reprofiling Machetes/Axes compared to knives.

When sharpening knives, it is wise to use as light of pressure as possible for sharpening/reprofiling, but with machetes and axes, heavier pressure is required (for me) or I'll be standing at the sharpener literally all day long just to reprofile, even with an 80 or 40 grit belt. Is applying more pressure a valid solution to this problem? It certainly takes a lot less time to remove that heap of steel needed to get the kind of edge I prefer. However, using this heavy pressure on knives would likely result in way to much steel being ground off. Agreed?

Problem #2
The tip.

I cannot stress enough how important it is to NOT drag the blade all the way across the belt. The belt will wrap itself around the tip just long enough to rip it off. This is why i take the tip halfway (at most) across the belt and simply back off. I think this has been discussed before multiple times and agreed upon.

Problem #3
Rounding off the apex with the leather stropping belt.

I have done this so many times before I actually realized what the problem was. I didn't think that the leather belt would have more flex than the abraisive belts. The belt does almost the same thing the abraisive belts do to the tip. It wraps around the apex and knocks it off, doing MUCH more harm than good. How to combat this? Feather light pressure.

Problem #4
3M Trizact 6 micron belt leaving black on the edges.

I know this sounds strange, but after I use the 6 micron trizact belt, my edges will sometimes have a blackened coloration mixed in with the mirror polish. It's not burning the edge, because there would be other colors besides black and I keep the blade cooled off anyways, and it isn't a dirty belt because I uyse a cleaning stick. This is the one problem that absolutely baffles me. Does anyone have any idea why in the world this happens? It's a huge pain to see an ugly black stain on the perfect mirror you worked so hard to achieve :(

Thanks for reading, and please feel welcome to discuss these problems and other possible solutions to them, please :)
 
Hello everyone has forgiveness by the English three-agulo Trizact same angle and same band leather belt pressure but not less edge rounding greetings
Joseph
 
Preface: I've done all of my belt sander sharpening on a relatively small and weak machine: The WorkSharp Ken Onion edition. It only has a 3/4" wide belt (12" x 3/4"), has NO platen, and can be set to run very slowly. I usually run it at something like 60% speed while doing most of my work and turn the speed down as I finish blades off.

Some of my comments below might not fit in well with larger or more powerful belt sanders. I honestly don't know because I haven't tried them! Maybe someone with more "big sander" experience will offer an opinion or two.

BladesB4Firearms said:
Problem #2
The tip.
Click to expand...

I've never rounded a tip with my sander, but I'm very conscious of the process. I've found that using my off hand to touch the tip and first 1/2 inch of the blade helps me enormously in *feeling* where the grinding is taking place near the tip. I can then change angles until I get *just* to the tip. Using sharpie helps a lot too of course. It also helps to understand the proper path of the blade across the entire surface of the edge bevel. This gets you very, very close to correct. The off hand pressure and feeling gets me the rest of the way there.

Problem #3
Rounding off the apex with the leather stropping belt.

I have done this so many times before I actually realized what the problem was. I didn't think that the leather belt would have more flex than the abraisive belts. The belt does almost the same thing the abraisive belts do to the tip. It wraps around the apex and knocks it off, doing MUCH more harm than good. How to combat this? Feather light pressure.
Click to expand...

I don't use a leather belt, but I sometimes use a purple belt that's very, very fine. It's also SUPER flimsy and has that tendency to wrap around the edge. With no platen, this is worse of course. I've had pretty decent success with "sneaking up on the edge" by decreasing my edge angle on these kinds of belts. By making the angle between the edge bevel and the belt smaller, I compensate for the "give" in the belt. This takes some experimentation. It may or may not work well for you.

Brian.
 
Good evening.

#1 Just a thought a lot of edge deterioration using a 40 grit belt with pressure and with out a cooling system, I figure you've considered this.
#2 Dead on here, always lift and remove before it gets across the center line of the belt.

#3 Have you considered edge trailing for this process?

#4 I'm using 3M plastic backed micron belts when I get this fine. I like them, they seem to run a little smoother than the Trizact belts and I use these also, good belt.


Fred
 
Good stuff Fred. I am gonna give those 3M belts a try next time I order. Can you list a source without breaking any rules?
Thanks, Russ
 
I use a Work Sharp Ken Onion and sometimes the Belt Grinding Attachment. I have a leather belt for each. A couple of quick comments on #3) and #4):

3) It's odd but sometimes light pressure works for me with the leather belts, but at other times heavier pressure has a better effect. I also recently came across this thread where knifemaker Daniel Koster recommends increasing your angle when finishing with a leather belt: http://www.bladeforums.com/forums/s...Tip-for-those-sharpening-their-knives-at-home

4) I was very interested to read your comments about the black discoloration on your otherwise mirror edge after using the 6 micron Trizact because I've experienced the same thing (more of a med.-dark gray actually) after I use the Norax 4 micron belt. I'd also love to know what's going on with this.

Andrew
 
I also have the 6u trizact but I've never had this problem. Bevel comes out close to a mirror. No idea what's causing that. You're right about the tip. The leather belt I always use on the platen with medium pressure with excellent results. Don't use the slack portion. With machetes and axes I do use more pressure and I use the slack portion. To make up for the extra deflection of the belt I grind at a shallower angle. I dip in water more often to counteract the heat. On the 3m micro finishing belts I started with those but became happier when I switched to trizact. One advantage to the plastic belts is they can be used cold. My problem with them though was because they don't have a cloth backing they really can't be used on the platen in my experience. I get chattering. Lee Valley sells them though if you want to try
 
I use a KMG rotary platen on most of my sharpening jobs. It allows
an excellent convex edge while keeping the belt somewhat cooler. No
chatter or splice bump.

If you are reprofiling an axe, you really have to put a fair amount of pressure
on it. And keep the blade cool by dunking frequently and not staying in one spot.
Keep it moving. Most axes are forged with too heavy a cross section and need
to be thinned. Make sure you ask what the axe will be used for. The cross-
section of a splitting axe will be thicker and "rounder" than an axe used for
cutting.

Bill
 
Just a thought, but machetes and axes/hatchets tend to be very low RC compared to sport cutlery. A good sized mill file can reprofile, thin etc very rapidly, and no issues with HT or taking a lot of life off a belt. Then go back and finish it off on the medium and higher grit belts.
 
If you are using a rubber "belt eraser" on your Trizact belt, that's where your black marks are coming from. The belt is too fine for the rubber to work and it melts and builds up in/on the belt. When you use the belt, it re-melts and deposits on the steel.
 
Depends on the axe. Gb axes are 58-59 hrc. That's harder than most knives. You're right though a bastard file will work on most cheap axes quite quickly. But a belt sander is still leagues ahead. To the op have you tried a 36 grit blaze or cubit eon belt. Much faster than your standard 40 grit belts

HeavyHanded said:
Just a thought, but machetes and axes/hatchets tend to be very low RC compared to sport cutlery. A good sized mill file can reprofile, thin etc very rapidly, and no issues with HT or taking a lot of life off a belt. Then go back and finish it off on the medium and higher grit belts.
Click to expand...
 
#1. I use a Norton Blaze SG Ceramic 60 grit for this. I have a sharpening business and occasionally get a real basket case. Even a pretty worn out Blaze 60 seems to make short work of fixing a real bear
 
Have you actually noticed that it gets dirty? That's one of the reasons I like trizacts. They really don't seem to load up because of the way they are designed. I use a standard pink eraser for my ceramic belts occasionally but never anything for the trizact belts except occasionally a sharp piece of mild steel to refresh when I notice the surface abrasive is getting dull
 
I'm just a neat freak I guess. It loads up and gets dark, but I've never noticed it effect the performance. Do you think I can eventually wear the melted eraser crap off?
 
Blades do you use a belt dressing? That would cause swarf to stick. Try like I mentioned a sharp piece of mild steel or something steel with a 90 degree edge and use a lot of pressure for a few seconds. It will refresh the belt and expose new sharp abrasive. May remove whatever is on it though I've never seen an eraser melt on a belt. If it's dressing use a rag
 
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