small wheel attachment
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Paul Mathews
Well-Known Member
Annoying as heck, isn't it? I try (I'm not always successful) to do as Tracy says, move fast, but also keep moving and keep the pressure light. I have a fixture that helps keep me square to the small wheel and I have to be careful or I'll hang up and create a really ugly divot.
Robert Dark
Well-Known Member
Those "ripples" are caused by the splice in the belt (there is a "hump" there), and it is more noticeable as the grits get finer.
Here a couple of tips (only good if you have a variable speed grinder) :
I assume you might be grinding a finger curve in the bottom side of your handle and trying to taper it out toward the rear of the handle. I also assume you might start with maybe a 60 grit belt.
Those "ripples" start with the 60 grit and are more noticeable as you go toward the back of the handle. Once you have the general shape that you want, stop grinding and put the knife in a vise. Draw file those ripples from the curve back to the rear until they are "leveled" out.
Now, as you progress through the grits (say next is a 220 grit), take a large felt tipped marker and mark the joint on the belt. Slow your grinder down really slow and start at the curve and quickly pull your tang toward you BETWEEN the marked belt joints. You have to stay off of the belt joints....... that is what causes the ripples.
Even though you marked the joints with a magic marker, you can also feel the joint as it comes by. Stay off of the belt joint.
It is very time consuming, but it works. Try it, you will like it.
Robert
Here a couple of tips (only good if you have a variable speed grinder) :
I assume you might be grinding a finger curve in the bottom side of your handle and trying to taper it out toward the rear of the handle. I also assume you might start with maybe a 60 grit belt.
Those "ripples" start with the 60 grit and are more noticeable as you go toward the back of the handle. Once you have the general shape that you want, stop grinding and put the knife in a vise. Draw file those ripples from the curve back to the rear until they are "leveled" out.
Now, as you progress through the grits (say next is a 220 grit), take a large felt tipped marker and mark the joint on the belt. Slow your grinder down really slow and start at the curve and quickly pull your tang toward you BETWEEN the marked belt joints. You have to stay off of the belt joints....... that is what causes the ripples.
Even though you marked the joints with a magic marker, you can also feel the joint as it comes by. Stay off of the belt joint.
It is very time consuming, but it works. Try it, you will like it.
Robert
Robert Dark
Well-Known Member
No, I use a flat "mill" file and start draw filing the bumps/humps from the curve toward the rear of the handle. If you don't get these bump/humps out to start with, as you proceed through the finer grits, your belt will only follow those bump/humps and make them worse.
Hope this helps,
Robert
Frank Niro
KNIFE MAKER
Thanks, Robert ! Frank
Justin King
Well-Known Member
I use larger diameter wheels whenever the radius allows and just try to keep it moving smoothly with light pressure. I only use my 3/4" small wheel for finger grooves and switch to the top wheel on my platen setup (2" wheel) for larger inside curves. I get rid of any minor ripples with sandpaper and a backing block when I fit up the edges of the scales.
Great explanation by Robert Dark in post #5, and this is one of the reasons why the machines will not completely replace good old-fashioned hand labor.:les:
I have not yet decided to purchase/use the small wheel attachment. Eventually I probably will, but I will utilize it only to form a precise radius, not to "follow the curve back".
Saving time and making things easier are the reasons we use our machines, so I can see where the initial hogging out of the entire profile can certainly be an advantage. But once we obtain the initial tight radius up front, I believe we are better served following the back with a larger wheel in order to increase the wheel footprint (in relation to size of the belt splice). This is in reference to post #2 by BossDog and post #11 by Justin King.
Again, I do not own or use one of these small wheel attachments. Currently, the smallest wheel I have for my grinder is 2". But I firmly believe in the adage of "using the right tool for the job", and my understanding is that the very small wheels have a specialized application- forming a tight radius.
Several factors contribute to this problem (the rippling effect), and it's up to each of us to find the solutions that work for the particular application at hand.
I like Robert Dark's solution, as it seems to be a great solution for the individual who may be limited in resources (e.g, "This is the only wheel I have to do this, and I can't afford a larger assortment of wheels right now.")
Some considerations for why different people get different results:
1. As always, we each have our own idea of what light pressure and fast feed rate mean. This is the unavoidable element that keeps us human.:3:
2. What type of belt is being used? What type of splice- butt or overlap? What type and size of abrasive?
Different methods of splicing (butt, overlap, etc.) the belt have a difference on the end result. Also, a splice with more angle will create a different "joint effect" than a splice that is more perpendicular.
As mentioned in post #5 by Robert Dark, the problem is usually more pronounced as grit becomes progressively finer. Makes sense to me, for two reasons: a) As with any abrasive application, going finer merely highlights any uncorrected imperfections of the previous step, and b) The abrasive particles are now smaller, yet the size of the splice probably remains the same (manufacturers do have their limitations). To me, this highlights the "joint effect".
The type of abrasive being used is important. Friability is the key here. I love the ceramic belts by Norton- they cut well and provide the best bang for the buck because they last so long. (Matter of fact, it's about time for me to order more.) But the downside is that pressure is required to keep them cutting well.
Refer to post #3 by Paul Mathews. It seems to me that light pressure would indeed help minimize the problem being discussed, so the most logical choice is a highly friable abrasive material that requires little pressure to stay sharp enough to cut. SC (silicon carbide) belts are certainly friable enough. Next up would be AO. The downside? Using these belts to shape metal means we're spending a lot of $$ on belts due to rate of wear.
So for abrasives more suitable for metal use (Zirconium oxide or ceramic) that provide reasonable service life, I modify my approach. In the end, it's all about keeping the belt sharp enough to cut without the use of high pressure.
Whenever I don't want to "lean into it", I like to "sharpen" the belt beforehand with a piece of scrap to expose fresh abrasive. This decreases the amount of pressure needed to effectively grind. If it seems to dull during the grind, I stop and "resharpen the belt" rather than apply more pressure on the actual project. This procedure can be frustrating due to the fact that not every material being shaped is the same, nor is every belt. In other words, belts wear (go dull) at different rates depending on a lot of factors, and most of us (including myself) simply want to "get it done". So we usually apply more pressure while grinding on the actual project.
So why do some people get good results while still using "normal" pressure?
3. Aside from belt quality, wheel hardness is most certainly an important factor.
Refer to posts #9 & #10. Indeed, some people are going to accomplish good results using a "spindle" sander, and one of my oscillating sanders has over 3000 hours of use. I have used them with diameters as small as 1/8" to as large as 10". As usual, using it for different purposes produces mixed results.
Consider that most of these machines (at least the ones most of us are are familiar with) cater to the woodworking market, so ideal design characteristics of the drums may differ from the wheels we use on our belt grinders.
As supplied by the manufacturer, most of my drums are around 40 duro. Great for sanding wood, because a softer backing is needed to prevent burning of the wood while still being able to apply "normal" pressure. But consider that the average hardness for our belt grinder wheels are somewhere around 70 duro or higher, because they're intended for grinding metal.
If I use the softer drum/sanding sleeve on metal instead of wood, I do indeed get a reduction in the ripple effect. But I cannot get a precisely defined radius with this method because the backing (soft drum in this case) "gives" at a greater rate than the metal being ground, and the result is a radius less defined than intended. In the meantime, I'm heating up the part and wearing out the abrasive band.
Switching to a harder drum gives a more defined radius, but introduces more ripples as I "follow back".:les: Same problem as using a belt.
Speaking of oscillating sanders, a large consideration is that the most commonly available sanding sleeves are the open-coat AO construction. Again, great for wood, not so great with metal. They work, but not in a cost efficient manner. Sure, the abrasive manufacturers will happily supply us with customized products, but in the end, the concept of a sanding drum and a belt are the same- they both have to be spliced, and both need to have a backing of some sort. The intention of both is to either create or follow a radius or curved profile.
Matter of fact, a sanding sleeve is nothing more than a tiny belt, and this is why I hold the belief that those who have had success with oscillating sanders should contribute that to hardness of backing material, not the type of machine.
The message I'm attempting to convey is this- if one has an oscillating sander, great. If one has the small wheel attachment for their belt grinder, great. I do not think either one is taking a back seat to the other. They're simply different approaches to the same concept. I have found no difference in using a 2" drum on my oscillating sander vs. a 2" contact wheel on the belt grinder provided they are equal hardness.
I like using the "spindle" sander, but that is only because it allows me to present the material to the machine in a fashion more comfortable and controllable to me. Sounds exactly like the concept of a horizontal belt grinder!
In the end, I'll probably purchase the small wheel attachment simply due to the fact that longer belts (belt grinder) last considerably longer than tiny belts (sanding sleeves). Also, belts are available in more variety than sanding sleeves, assuming common stock. And then I'll convert one of the grinders to horizontal use to simulate the experience of the "spindle" sander.
Good luck,
Robert
I have not yet decided to purchase/use the small wheel attachment. Eventually I probably will, but I will utilize it only to form a precise radius, not to "follow the curve back".
Saving time and making things easier are the reasons we use our machines, so I can see where the initial hogging out of the entire profile can certainly be an advantage. But once we obtain the initial tight radius up front, I believe we are better served following the back with a larger wheel in order to increase the wheel footprint (in relation to size of the belt splice). This is in reference to post #2 by BossDog and post #11 by Justin King.
Again, I do not own or use one of these small wheel attachments. Currently, the smallest wheel I have for my grinder is 2". But I firmly believe in the adage of "using the right tool for the job", and my understanding is that the very small wheels have a specialized application- forming a tight radius.
Several factors contribute to this problem (the rippling effect), and it's up to each of us to find the solutions that work for the particular application at hand.
I like Robert Dark's solution, as it seems to be a great solution for the individual who may be limited in resources (e.g, "This is the only wheel I have to do this, and I can't afford a larger assortment of wheels right now.")
Some considerations for why different people get different results:
1. As always, we each have our own idea of what light pressure and fast feed rate mean. This is the unavoidable element that keeps us human.:3:
2. What type of belt is being used? What type of splice- butt or overlap? What type and size of abrasive?
Different methods of splicing (butt, overlap, etc.) the belt have a difference on the end result. Also, a splice with more angle will create a different "joint effect" than a splice that is more perpendicular.
As mentioned in post #5 by Robert Dark, the problem is usually more pronounced as grit becomes progressively finer. Makes sense to me, for two reasons: a) As with any abrasive application, going finer merely highlights any uncorrected imperfections of the previous step, and b) The abrasive particles are now smaller, yet the size of the splice probably remains the same (manufacturers do have their limitations). To me, this highlights the "joint effect".
The type of abrasive being used is important. Friability is the key here. I love the ceramic belts by Norton- they cut well and provide the best bang for the buck because they last so long. (Matter of fact, it's about time for me to order more.) But the downside is that pressure is required to keep them cutting well.
Refer to post #3 by Paul Mathews. It seems to me that light pressure would indeed help minimize the problem being discussed, so the most logical choice is a highly friable abrasive material that requires little pressure to stay sharp enough to cut. SC (silicon carbide) belts are certainly friable enough. Next up would be AO. The downside? Using these belts to shape metal means we're spending a lot of $$ on belts due to rate of wear.
So for abrasives more suitable for metal use (Zirconium oxide or ceramic) that provide reasonable service life, I modify my approach. In the end, it's all about keeping the belt sharp enough to cut without the use of high pressure.
Whenever I don't want to "lean into it", I like to "sharpen" the belt beforehand with a piece of scrap to expose fresh abrasive. This decreases the amount of pressure needed to effectively grind. If it seems to dull during the grind, I stop and "resharpen the belt" rather than apply more pressure on the actual project. This procedure can be frustrating due to the fact that not every material being shaped is the same, nor is every belt. In other words, belts wear (go dull) at different rates depending on a lot of factors, and most of us (including myself) simply want to "get it done". So we usually apply more pressure while grinding on the actual project.
So why do some people get good results while still using "normal" pressure?
3. Aside from belt quality, wheel hardness is most certainly an important factor.
Refer to posts #9 & #10. Indeed, some people are going to accomplish good results using a "spindle" sander, and one of my oscillating sanders has over 3000 hours of use. I have used them with diameters as small as 1/8" to as large as 10". As usual, using it for different purposes produces mixed results.
Consider that most of these machines (at least the ones most of us are are familiar with) cater to the woodworking market, so ideal design characteristics of the drums may differ from the wheels we use on our belt grinders.
As supplied by the manufacturer, most of my drums are around 40 duro. Great for sanding wood, because a softer backing is needed to prevent burning of the wood while still being able to apply "normal" pressure. But consider that the average hardness for our belt grinder wheels are somewhere around 70 duro or higher, because they're intended for grinding metal.
If I use the softer drum/sanding sleeve on metal instead of wood, I do indeed get a reduction in the ripple effect. But I cannot get a precisely defined radius with this method because the backing (soft drum in this case) "gives" at a greater rate than the metal being ground, and the result is a radius less defined than intended. In the meantime, I'm heating up the part and wearing out the abrasive band.
Switching to a harder drum gives a more defined radius, but introduces more ripples as I "follow back".:les: Same problem as using a belt.
Speaking of oscillating sanders, a large consideration is that the most commonly available sanding sleeves are the open-coat AO construction. Again, great for wood, not so great with metal. They work, but not in a cost efficient manner. Sure, the abrasive manufacturers will happily supply us with customized products, but in the end, the concept of a sanding drum and a belt are the same- they both have to be spliced, and both need to have a backing of some sort. The intention of both is to either create or follow a radius or curved profile.
Matter of fact, a sanding sleeve is nothing more than a tiny belt, and this is why I hold the belief that those who have had success with oscillating sanders should contribute that to hardness of backing material, not the type of machine.
The message I'm attempting to convey is this- if one has an oscillating sander, great. If one has the small wheel attachment for their belt grinder, great. I do not think either one is taking a back seat to the other. They're simply different approaches to the same concept. I have found no difference in using a 2" drum on my oscillating sander vs. a 2" contact wheel on the belt grinder provided they are equal hardness.
I like using the "spindle" sander, but that is only because it allows me to present the material to the machine in a fashion more comfortable and controllable to me. Sounds exactly like the concept of a horizontal belt grinder!
In the end, I'll probably purchase the small wheel attachment simply due to the fact that longer belts (belt grinder) last considerably longer than tiny belts (sanding sleeves). Also, belts are available in more variety than sanding sleeves, assuming common stock. And then I'll convert one of the grinders to horizontal use to simulate the experience of the "spindle" sander.
Good luck,
Robert
Frank Niro
KNIFE MAKER
I use a router with a slow down switch and the drums. It works super where the drums will fit in. Frank