I am probably the one guilty of telling people to buy a 1"x30" belt sander.
I am pretty sure I recently suggested as much. <img src="/ubbthreads/images/graemlins/blush.gif" alt="" />
I don't know everybodies qualifications for use of tools, so for me to generally state that everybody should get one could probably cause some problems.
But, I personally highly recommend a belt sander to "those capable of using one".
So, as much as I empowered people to get one before. I further empower you to use your own judgement and be responsible for all effects of purchasing, owning and using such tools. Be carefull!!! - especially when grinding sharp knives and similarly sharp tools!!! <img src="/ubbthreads/images/graemlins/thumbup.gif" alt="" />
If you read certain posts over at Bladeforums and knifeforums, even the professionals talk about an occassional knife going flying!!! <img src="/ubbthreads/images/graemlins/ooo.gif" alt="" /> <img src="/ubbthreads/images/graemlins/shocked.gif" alt="" />
They especially warn about buffers! The loose knit material is apparently notorious for grapping and throwing blades.
Hold the knife carefully.
Don't grind off knuckles.
Wear eye protection.
Wear masks.
Keep loose sleeves and similar clothing away from wheels and belts - as they can catch and quickly grap your arm or similar causing a knife to fling or similar.
Etc. etc.!
Short of having a professional knife-maker teach you, there really isn't much to substitute for lots of practice if making modifications to nice knives.
And just heads up - Pay Attention! - Look for possible issues.
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The platen is crucial for flat grinds.
Not using the platen - when grinding with a flexed belt seems to be generally referred to as "Slack belt grinding" - creates a convex grind.
The more you push or the looser your belt is the more convex the blade will be.
More convex edges and/or more obtuse grind angles are sometimes better for very thick blades or blades to be used as choppers as the curve can add reinforcing strength to the edge. - personal preference and use (????).
More flat grinds and/or more acute grind angles are often better for smaller knives not heavily used for chopping and intended for sharp cutting.
Most of the typical do-it-yourself belt sander don't truly have much in the way of tightening the belt. The adjustment screw can tighten it some, but usually also controls alignment. So, your ability to tighten much isn't really there much.
So, sometimes you will need to alter the amount of pressure against the belt for different radius curves or flatter grinds on your convexing.
As Vic mentioned, the proper belts are easily the most realistic way to get a proper finish or proper edge. Felt or leather belts with compounds go even further. *Hint: only use one felt or leather belt per given compound. It is generally not considered good to use multiple compounds on one belt as you will get mixed results. Whatever color compound you put on your belt will eventualy turn black and make them hard to tell apart. I heard of a good way to keep them correct is to keep them in a labeled zip-lock bag.
I don't always have to remove the platen to do some slack belt grinding on my sander, but it depends on your platen (and how your platen is attached), size of blade and your technique.
The tables do just tend to be in the way for most anything related to knife modifications. The general concept of the table is to help give you a fixed angle against the platen - say for a 90 degree grind. But, most knife modifications involve a knife with a handle already attached and it is pretty hard to ever get much if any use out of the table. It is just in the way.
But, don't loose or throw away the table either. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />
I honestly don't know how people would properly hollow grind on a belt sander. It is my understanding that hollow grinding is done on various sized abrasive wheels with a bench grinder.
But, be careful if you think you can go buy a bench-grinder to work on or modify a heat-treated or already sharp knife. The typical Bench grinders typically run at VERY high speeds. I think most knife-makers would only use this type of bench-grinder prior to heat treatment AND prior to the edge being sharpened. The high speeds WILL easily damage a heat treatment and would likely be dangerous with a sharp blade.
I think the typical hollow ground knife goes like this:
1) cut and rough shape blank
2) grind primary grind on bench grinder
3) drill holes for handle
4) heat treat
5) Clean and finish blade after heat treat
6) add and finish handle
7) sharpen
** Notice sharpening is last and heat treat is after bench grinding. I think most knife-makers seem to use belt sanders with various belts and compounds for sharpening.
** I would highly recommend any knife be kept away from a bench grinder if already heat treated and/or already sharp!
If you are referring to grinding or sharpening the recurve of an edge on a knife such as a Yard Guard with a belt sander, this is done by changing the angle of the blade - same as if grinding or sharpening any curve in the belly of a blade. - This Takes some Practice!!!
I have tried tinkering with some hollow grind areas on the wheel of the belt grinders, but I have not been thrilled with my results. Very hard for me to achieve anything consistent on the wheels.
If you are hoping to strip, modify or reshape a hollow ground blade with a belt sander, I don't really have any good advice as I don't really know how it is done. But, I assume knife-makers only use their belt sanders to clean or finish heat treated blades and don't use bench-grinders. I assume they have special platens or special wheels.
My belt sander's wheels are very convexed and I just can't really get good results when trying to do anything on my wheels. This might even be dangerous for some reason (????).
I have not seen a radiused platen (????). But, I have read where some knife-makers grind and shape their platens to create a certain style or shape to suit their own personal needs or techniqes such as shape of a plunge line. There are a lot of knife-maker opinions and people with their own certain techniques for using the platen.
Research Bladeforums or Knifeforums for term: platen
The belt curve and shape as well. Certain types of belts more or less than others. Again, takes practice.
Best tip I can think of for beginning with a Belt sander: Go slow! <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />
Also, if you have a Drill press, I found a "Kit" with various sized drum sanding heads at Sears that has been pretty helpful for a lot of concave shaping - such as choils and handles and such. Something to consider.....
I already had a drill press and find lots of home projects I use it for. It can do a lot more precision than a regular drill press and it really helps free up your hands which can be very helpful.
But, a fairly cheap Delta drill press or similar would start at about $100 and go up. I have a counter-top model that I can move around, BUT it is still pretty heavy to move. I have been considering buying or building a table I can roll it around on, but it would need to be able to roll off and back onto the edges of my garage. And then I would need to take up floor-space in my garage.
I have lots of pretty expensive tools as I do lots of home renovation projects. Compressors, table saws, miter saws, nail guns and many other high dollar tools that make my drill press seem like a good deal. Heck, most little 12V, 14.4V and 18V cordless drills cost more than $100. But, not everybody will justify a drill press (?????).
I am actually curious to find out if I can purchase certain carbide milling bits to use in my drill press for certain little machining metal projects and such. It can take a very long time to reshape certain knives with a grinder. Maybe a caride bit could be a lot faster (????) I don't know much about machining metal. I generally work with wood. So, I still have to do a fair amount of research on that....
Anyway, again, Good luck!
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