Belt sander speeds

Steel-Junky

Steel-Junky

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So I was looking at some belt sanders here recently. I noticed one model in particular that was a 4"X36" with Disc Sander as well. It had a speed of 1,100 FPM. If I understand that... that's Feet Per Minute right? Which would translate into about 18 feet a second. That's not terribly fast is it? By which I mean it might be a good speed for sharpening and reprofiling knives. I found that Jantz sells 4X36 belts in 400 grit which would put a nice edge on a knife and you could then finish it up with a power strop or by hand or whatever. Is 1,100 FPM gonna be alright with sharpening knives or is this too fast and i just don't understand the rating. Thanks everyone.
 
Never seen one rated in FPM always in RPM. I have a HF 1x30 it runs at over 3400 RPM's and IMO that's too fast. If you use it for a while you can get comfortable with it but its still to easy to ruin a blade. I think if I had a speed control my ideal speed would be between 500 and 1000.
 
knifenut1013 said:
Never seen one rated in FPM always in RPM. I have a HF 1x30 it runs at over 3400 RPM's and IMO that's too fast. If you use it for a while you can get comfortable with it but its still to easy to ruin a blade. I think if I had a speed control my ideal speed would be between 500 and 1000.
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3400 RPM is the rotation speed of the wheel though right... the belt doesn't make a complete 3400 rotations per minute does it?

1100 fpm would be 220 inches per second. That doesn't sound very fast to me... but I have nothing to base it on.
 
Steel-Junky said:
3400 RPM is the rotation speed of the wheel though right... the belt doesn't make a complete 3400 rotations per minute does it?

1100 fpm would be 220 inches per second. That doesn't sound very fast to me... but I have nothing to base it on.
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Um.... I don't know.

Its fast though.
 
I just use a 1"X30" belt sander that I bought from my local hardware store, it goes really fast, maybe too fast but I haven't had a problem other than the blade trying to wobble down :mad:.
 
Most one speed belt sanders are a little to fast for sharpening knives especially for a novice. I know that no one wants to be considered a novice. You can ruin a blade by removing too much or overheating the blade at the edge. Remember the edge is thin and does not take to much to overheat. On a fast belt you would need light pressure and keep dipping the blade in water to keep it cool. There are some good tips out there on how to modify some sander to a step pully system, which makes it more user friendly for sharpening blades. (This system allows you to slow the belt down considerably) Practice on low value knives when you start. This is just my opinion. Good luck.
 
rpttrsn said:
Most one speed belt sanders are a little to fast for sharpening knives especially for a novice. I know that no one wants to be considered a novice. You can ruin a blade by removing too much or overheating the blade at the edge. Remember the edge is thin and does not take to much to overheat. On a fast belt you would need light pressure and keep dipping the blade in water to keep it cool. There are some good tips out there on how to modify some sander to a step pully system, which makes it more user friendly for sharpening blades. (This system allows you to slow the belt down considerably) Practice on low value knives when you start. This is just my opinion. Good luck.
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Is 1100 FPM at the belt too fast though? That's the answer I'm after... is it any slower or faster than a belt sander that turns 3400 RPM at the shank?
 
I have on of those 4X36 sanders with a disk sander attached that I primarily use to flatten handle material. Mine runs slow but look at the motor speed and that will tell you a lot about it. Mine runs at 1725rpm. The belt speed is good enough for sharpening if your careful but where the belt sits is too far away from the edge to sharpen around the tang especially for pocket knives. Also the edge is rounded so even if you track the belt to the edge it still won't get to it. This is just the experience I have from mine so look it over good before you buy it. If your going to buy something and use it a lot I second the Kalamazoo 1x42. That is a much better machine and removing the platen will give you the ability to put a good convex edge on your knives if you want. You can get one for around $200 from Jantz the last time I checked. Good luck.
 
rpttrsn said:
If you check for the Kalamazoo 1"x42" belt grinder that many knife sharpeners and makers use, you will find that its speed is listed at 1800 SFPM.

http://www.kalamazooindustries.com/belt_sanders.asp
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Thanks so much... what is SFPM? I assume PM is Per Minute... what is the SF? Is that slow enough to sharpen well and have less worry about rounding tips and ruining edges? You'll have to forgive me... I'm a little power tool stupid. Power hand tools like drills, jig and circular saws are the limits to my power tool knowledge. Why do guys use those 3450 RPM belt grinders if this thing is available? I always thought that to get a belt grinder that wasn't 3450rpm... you had to spend thousands of dollars.
 
Your higher speed belt grinders is for removing material at a higher rate of speed. When you have a piece of steel and want to get it into the shape of a knife or anything else that you are making, you don't want to spend any more time then you have to doing it. Prior to hardening the knife you also don't have to worry as much about the temperture of the material. When putting the finishing touches to a knife you want control over what you are doing. The slower belt will add to that control and since you are not roughing out, but rather finishing you project you don't need the higher speed or rough sanding belts. With the high speed it can take seconds to ruin many hours of work. I'm sure that there are some out there that can control their work using the high speed when completing a knife but this takes a light touch and considerable skill which comes with time. I have been a machinest for 40 years and had to repair parts to million dollar machines. Would much rather run the belt grinder slower then faster when finishing up these presision machine parts.
I don't think a 4" belt sander is what I would use to reprofile or sharpen a knife. The belt is too wide and it will be very difficult to sharpen near the tang due to the plate behind the belt. Also not the best for a convex edge.
I just ordered the Kalamazoo 1"x42" for $225 (includes shipping) at a local supply shop. If I ordered the Delta SA180 about $135., I would have to add another $60 or so in parts + time to slow it down. The quality between the two does not compare IMO. This is a great forum with lots of info. Good luck in you sharpening.
 
rpttrsn said:
Your higher speed belt grinders is for removing material at a higher rate of speed. When you have a piece of steel and want to get it into the shape of a knife or anything else that you are making, you don't want to spend any more time then you have to doing it. Prior to hardening the knife you also don't have to worry as much about the temperture of the material. When putting the finishing touches to a knife you want control over what you are doing. The slower belt will add to that control and since you are not roughing out, but rather finishing you project you don't need the higher speed or rough sanding belts. With the high speed it can take seconds to ruin many hours of work. I'm sure that there are some out there that can control their work using the high speed when completing a knife but this takes a light touch and considerable skill which comes with time. I have been a machinest for 40 years and had to repair parts to million dollar machines. Would much rather run the belt grinder slower then faster when finishing up these presision machine parts.
I don't think a 4" belt sander is what I would use to reprofile or sharpen a knife. The belt is too wide and it will be very difficult to sharpen near the tang due to the plate behind the belt. Also not the best for a convex edge.
I just ordered the Kalamazoo 1"x42" for $225 (includes shipping) at a local supply shop. If I ordered the Delta SA180 about $135., I would have to add another $60 or so in parts + time to slow it down. The quality between the two does not compare IMO. This is a great forum with lots of info. Good luck in you sharpening.
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So 1800 SFPM is a good speed for sharpening and doesn't require tons of experience to master? I intend to use some cheapo knives to practice... but I just don't want a tool that one false slip and I just ruined a $500.00 Busse Combat.
 
rpttrsn said:
1800 SFPM should be fine. Practice practice, practice before touching that Busse :D
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Thanks... That'll be the one I get then. And don't worry... even when I'm ready skill wise to do my Busse Knives... I'm probably gonna still practice for a few more weeks just to make sure LOL.
 
Go to yard sales and get a bunch of cheap kitchen knives to practice on. You'll be happy you did! Do you know what happens when you overheat a tip and sand it? I do, unfortunately. It turns a nice pretty blue, then goes BLING, and travels at warp factor 8 and embeds into your wall....
 
sodak said:
Go to yard sales and get a bunch of cheap kitchen knives to practice on. You'll be happy you did! Do you know what happens when you overheat a tip and sand it? I do, unfortunately. It turns a nice pretty blue, then goes BLING, and travels at warp factor 8 and embeds into your wall....
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Where you using a sander like this or one that was moving 3450 RPM? I've heard it's easy to ruin a tip on the fast ones... that's why I don't mind spending a little more money to get one that is slower. To start I probably won't use any grit under 400 just because I don't want anything too agressive. As I gain skill I'll move into rougher grits to begin shaping edges... but for now... it's strickly a sharpener.
 
Steel-Junky said:
I probably won't use any grit under 400 just because I don't want anything too agressive. As I gain skill I'll move into rougher grits to begin shaping edges... but for now... it's strickly a sharpener.
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Just be careful about the heat with the 400. You will have the tendency to either press harder or leave the blade on longer to get it to cut. you will burn the tip very quick doing that. Honestly you will get the hang of it quick just practice on some old kitchen knives as said before. Try a dull 220 grit first because I think its a little more forgiving than a new 400 and won't create as much heat. This is all from my own experience and as I've said before once you try a few methods you will find your own "right way" to do it. Good luck and have fun.
 
Steel-Junky said:
Where you using a sander like this or one that was moving 3450 RPM? I've heard it's easy to ruin a tip on the fast ones... that's why I don't mind spending a little more money to get one that is slower. To start I probably won't use any grit under 400 just because I don't want anything too agressive. As I gain skill I'll move into rougher grits to begin shaping edges... but for now... it's strickly a sharpener.
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I've got the Harbor Freight 1750 one. You can ruin anything if you give it to me. Keep the blade moving, especially at the tip. And have a dunk tank. And don't give it to me. :eek:

I'm not very good at it, but I do enjoy doing it!
 
The trick with belt sanders is to try and use sharp belts, and move consistently and quickly across the edge. Use a very light touch, I prefer using a "slack" portion of the belt between the platen and a wheel. Never linger in one spot too long to remove more material, just make a few more passes. Done right the faster belt speeds won't be an issue. I do recommend finishing on a stone followed by a strop though. If it sparks then that means the steel coming off is hot, while this won't affect the blade I believe that any wire edge left by a fast beltsander has been overheated, a couple passes on a stone should remove any of that. Dull belts while not sparking, also don't remove that metal that's been heated by belt friction, so instead of being flung off as harmless sparklies you run the risk of actually overheating and damaging the blade.
 
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