How much magnification do I need to find the sweet spot?
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Hello there,
I’m asking myself how much magnification do I need to find the sweet spot placing a knife in the clamp holder. Do I really have to buy an USB-microscope or would a magnifying glass be sufficient?
A magnifying glass would be handier as I need no computer and it would cost less. For example a glass with a magnification of 30x and led light would cost just 17€ (https://www.amazon.de/Beleuchtet-Verzerrungsfreier-Doppelglaslinse-Kleingedruckten-Briefmarken/dp/B07MQ4CX2Q/ref=sr_1_6?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&keywords=lupe&qid=1562749733&s=gateway&sr=8-6).
With kind regards,
Thomas
Thomas, you can find the sweet spot with a sharpie marker painted across the bevel and the lighted magnifier you linked. You’re looking for the area where the ink is removed for the sweet spot.
The USB Microscopes we use are for very close up examination of the very knife edge; the apex.
Marc
(MarcH's Rack-Its)5 users thanked author for this post.
Hi Thomas! If you have good vision or good bifocals you don’t need a magnifying glass to find the sweet spot but it does help.
The USB microscope does add a layer of additional complication and require room for the laptop or tablet. However it really does make for a better understanding of what needs to be done and what has been done.
For instance, I have attached a couple of before, during and after photos of different areas of the same knife. You can see the damage that needs to be removed by inspecting before you start, and then during you can see if you have removed enough steel to fix the area and then nearing the end you can see that you have removed most of the scratches of all the previous stones. During the sharpening session I will inspect the knife several times during each grit but I don’t take photos every time I look. If so inclined you can document your progress as a learning tool to compare the results as your stones break in. The USB scope also is the Bees Knees for removing splinters, there are many other uses you will find once you have one!
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Hey Thomas and welcome back. Like you, I’m new to the WE system although I’m not new to sharpening knives. I used the EdgePro system for years and I thought it was doing a pretty good job until I understood that there were other solutions available to achieve much better results. I started out looking at my knife edge using a jeweler’s loupe with both the 30x/60x lenses https://www.amazon.com/gp/product/B01DWG89KQ/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1. It worked fine for awhile but as I matured in my skillset, I listened to other members on this forum and bought a USB microscope. The difference was just amazing, I could see details on my laptop screen which were barely discernible with the loupe. The grooves left by all the stones just popped out as did the actual blade apex. I have attached before and after pictures of a friend’s kitchen knife with a factory edge. I began with a 100-grit diamond stone and went all the way to the 1600-grit ceramic. As you might imagine, he was very pleased. Keep this in mind for a long time solution because it really does make a difference.
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This is all and well and good, but your bottom-line question was really, what do you need to see if you’re finding the sweet spot.
As Marc says, the black marking pen is the one major key to getting there. I, however, have found that I often cannot see (really old eyes) the last sliver of black along the apex. and at least some amount of magnification is the next key. Loupes are very effective and happily inexpensive, but they do require that you move your face and eye to directly above, close to and along the length of the edge. Kind of awkward and even a little bit risky. The USB is the best bang for the buck here, but does require that you come up with an older laptop that’s been put out to pasture. For a new user not sure of how far you want to go down the rabbit hole, I’d go with a loupe of 10-30X. Some even have an LED light built in to them.
And to be clear for new members of the forum, the “sweet spot” method of finding an optimal mounting position is intended to match the existing or factory bevels. Not necessarily the optimal bevel profile for a given knife.
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to be clear for new members of the forum, the “sweet spot” method of finding an optimal mounting position is intended to match the existing or factory bevels. Not necessarily the optimal bevel profile for a given knife.
I do agree with Tom, …0nce the knife is mounted in the “sweet spot” position it is a good efficient clamping position to profile the knife bevel any way you choose to, or to match the existing bevels if that is your choice.
Marc
(MarcH's Rack-Its)3 users thanked author for this post.
Thank you all for your answers!
Sorry for the late reply but there were other things taking my time.
You can see the damage that needs to be removed by inspecting before you start, and then during you can see if you have removed enough steel to fix the area and then nearing the end you can see that you have removed most of the scratches of all the previous stones. During the sharpening session I will inspect the knife several times during each grit but I don’t take photos every time I look.
Hello airscapes,
thank you for your pictures! I’m sure it’s great to repair knives but as I’m more interesting in cooking than in sharpening knives I’m not sure if a microscope would be really useful for me. Would the damage in your pictures have an impact on how good the knife slices tomatoes, onions or cutting meat or how long it stays sharp?
Keep this in mind for a long time solution because it really does make a difference.
Hello Richard,
to you also thank you for the Pictures. Perhaps I’ll add a microscope later on when I have more time. At the moment I would like to Keep sharpening knives as simple as possible. I know myself – if it get’s too complicated I won’t ever start with it. 😉
And to be clear for new members of the forum, the “sweet spot” method of finding an optimal mounting position is intended to match the existing or factory bevels. Not necessarily the optimal bevel profile for a given knife.
Hello!
Thank you for your opinion. That it’s a little bit risky to use a loupe I’ve never thought about, thank you for the good hint. At least I’ll be very careful.
I’ve read the tutorial about finding the sweet spot (otherwise I wouldn’t have known that there is such thing). So I know already what it’s for: finding the optimal clamping position that covers most of the already existing bevel so that the part of the bevel that get’s a new profile is as little as possible.
There come’s another question to my mind:
What stone do I have to start with when thanks to the sweet spot 90% of the existing bevel is covered? 400?
Greetings from germany,
Thomas
In my opinion, use a very fine grit. You’re only removing marker to see where you are hitting the bevel. I typically use my ceramics. My finest diamond is 1000. No need to introduce a deep groove when trying to find the sweet spot.
Hello Mike,
sorry, my question may have been a little bit inaccurate.
Of course you are right, to find the sweet spot i use the finest stone I have because I just want to remove the marker on the bevel.
What I wanted to ask: after I’ve found the “sweet spot” and 90% of the knife’s given bevel are covered in this clamping position (so only 10% need’s to get the profile adjusted) what stone do I begin with to sharpen the knife?
I hope that’s more understandable – sorry for my bad english.
You choose a stone grit that accomplishes what you need it to. One that is coarse enough to remove the steel from where you want it removed as quickly and easily as possible with the least amount of effort exerted and the least amount of deeper scratches applied then necessary.
I would start at 600 grit and if that doesn’t do what you need quickly enough and with very little to a reasonable amount of effort. Then I’d step down coarser to the 400 grit. If the knife is in very good shape with very little edge damage you might be able to start even finer. Maybe at 800 grit.
It’s a balance between the edge condition your beginning with and steel hardness. Remember even if your sweet spot clamping position is covering 90% of the edge your left to reprofile 10% of the edge, the first time out. The other 90% your still working on also, to impart the same even scratch pattern across the entire blade edge to make the edge sharp. uniformed and even across the entire knife.
If you start out too fine and it’s not getting it done, step down a grit and try again. You may find that works well or you may decide it’s better to step down a grit again. Remember to double check your stone angle settings with each and every grit change to insure precision.
I’m sharpening kitchen knives 90% of the time. I never sharpen any knife without the help of the USB Microscope. Once you’ve used one it’s hard not to keep using it.
Marc
(MarcH's Rack-Its)
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