Sanding Choils and Spines

For questions/topics that don't fit into the other, more specific forums.
Sean-in-AK
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Re: Sanding Choils and Spines

Post by Sean-in-AK » Sun Jul 14, 2019 11:37 am

Automotive painter here. So I have quite a bit of time spent playing with the different types of sandpaper and using them on various substrates.

There are 3 basic types of abrasives used on automotive sandpaper’s. Aluminum Oxide, Ceramic and diamond. Within these types of abrasive there are varying qualities, but that’s somewhat irrelevant for the task at hand.

Aluminum Oxide is the softest abrasive of the group, it will cut the slowest and wear the fastest when being used directly on hard steel. It is also the cheapest and considerably so. This is also the most common abrasive used for automotive sanding.

Ceramic abrasive is considerably harder and will cut faster and last longer than aluminum oxide paper. You will go through less material to complete the same job but the material cost is more.

Diamond abrasive will cut the fastest and last the longest of them all. It is also the most expensive and not as easy to source outside of automotive paint and material supply stores.

So what does all this mean in regard to sanding knives?

When sanding the spine of a knife, the contact area of the knife to the paper is very small and very hard. That combination is going to cause the abrasive grit to be stripped from the paper at a much faster rate than sanding on a larger flatter surface area. This is going to be true no matter what abrasive type is being used. It’s just the nature of sandpaper, which is grit glued to paper.

For doing choils and spines I would go with the much less expensive aluminum oxide papers and just plan to use a fair amount of it. The added benefit of the faster cutting and longer lasting papers will not be fully realized due to the nature of this type of sanding.... I would add an exception, if you have more money than time, then the added cost might be worthwhile to that individual.

If a considerable amount of material needs to be removed to get the desired roundness or smootheness, I would strongly consider starting with some diamond needle files to rough in the shape and do the heavy lifting of material removal. Then move on to a sandpaper progression to achieve the desired smootheness and shine.

Carlo
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Re: Sanding Choils and Spines

Post by Carlo » Sun Jul 14, 2019 12:34 pm

Thank you Sean-in-AK! What do you think of these pads Mark sells?
https://www.chefknivestogo.com/3x4sotomisap.html

I’m interested in doing some softening of a spine & choil but not sure I’m motivated enough to search for a file. And I’ve sanded plenty of things with wet/dry and am not looking forward to going that route.

gastro gnome
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Re: Sanding Choils and Spines

Post by gastro gnome » Sun Jul 14, 2019 9:10 pm

Carlo wrote:
Sun Jul 14, 2019 12:34 pm
Thank you Sean-in-AK! What do you think of these pads Mark sells?
https://www.chefknivestogo.com/3x4sotomisap.html

I’m interested in doing some softening of a spine & choil but not sure I’m motivated enough to search for a file. And I’ve sanded plenty of things with wet/dry and am not looking forward to going that route.
Pretty sure those are aluminum oxide for what it is worth. I have some of these I bought at work (I work for an industrial supply company) and the general sense I get is that they can be used to sand down a little bit but there's probably not enough grit on the small 2x2 pads to take a sharp-angled choil or neck to smooth and rounded. Again, I don't have these exact products and I still haven't done this work myself, but that's my assumption from the discussion here and elsewhere (and looking at the size of the pads).

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Jeff B
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Location: Kentucky

Re: Sanding Choils and Spines

Post by Jeff B » Sun Jul 14, 2019 9:24 pm

Carlo wrote:
Sun Jul 14, 2019 12:34 pm
Thank you Sean-in-AK! What do you think of these pads Mark sells?
https://www.chefknivestogo.com/3x4sotomisap.html

I’m interested in doing some softening of a spine & choil but not sure I’m motivated enough to search for a file. And I’ve sanded plenty of things with wet/dry and am not looking forward to going that route.
You definitely want paper here and not pads. These are made more for refinishing a surface not rounding edges of metal.
If God wanted me to be a vegetarian he wouldn't have made animals taste so good.

Carter
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Re: Sanding Choils and Spines

Post by Carter » Sun Jul 14, 2019 9:51 pm

Indasa Redline papers work well. Better than the Norton/3M paint & body papers. Also, files can be use for the initial work.

Sean-in-AK
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Location: Juneau, AK

Re: Sanding Choils and Spines

Post by Sean-in-AK » Mon Jul 15, 2019 12:22 am

Carlo wrote:
Sun Jul 14, 2019 12:34 pm
Thank you Sean-in-AK! What do you think of these pads Mark sells?
https://www.chefknivestogo.com/3x4sotomisap.html

I’m interested in doing some softening of a spine & choil but not sure I’m motivated enough to search for a file. And I’ve sanded plenty of things with wet/dry and am not looking forward to going that route.
I have never used those, However to me they don’t seem like a good choice for rounding a spine or choil. They look great for removing patina or a ku finish. Or for using in a progression to polish a blade. Soft products like that get int low spots that sandpaper and sanding blocks won’t. So if you wanted to polish something without having to TrueType flatten the surface they would be good.

If you want to do the initial rounding fast, something like this works well. They make them in various grits, and they are cheap.
Fatmingo 7" Premium-grade Diamond Needle Files Set Grit120,Black Nickel Diamond Coated Variety Shapes Jewelers Files Kit for Metal/Ceramic/Jewelry/Glass filing https://www.amazon.com/dp/B06XS7WGRV/re ... lDbEGNEMQJ

Carlo
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Location: NYC

Re: Sanding Choils and Spines

Post by Carlo » Mon Jul 15, 2019 5:59 am

Thanks guys, and thanks for the link, Sean-in-AK!

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Jeff B
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Re: Sanding Choils and Spines

Post by Jeff B » Mon Jul 15, 2019 12:32 pm

I like cloth backed abrasives or emery cloth, something like this - https://smile.amazon.com/Assorted-Abras ... way&sr=8-7 or this https://smile.amazon.com/ABN-Abrasive-P ... ay&sr=8-11
There are many different brands and choices.
If God wanted me to be a vegetarian he wouldn't have made animals taste so good.

delmar
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Re: Sanding Choils and Spines

Post by delmar » Mon Jul 15, 2019 7:23 pm

Jeff B wrote:
Mon Jul 15, 2019 12:32 pm
I like cloth backed abrasives or emery cloth, something like this - https://smile.amazon.com/Assorted-Abras ... way&sr=8-7 or this https://smile.amazon.com/ABN-Abrasive-P ... ay&sr=8-11
There are many different brands and choices.
I said it before - this is the easiest and most cost effective for me. Protect and secure blade, then go back and forth over spine like you are polishing a shoe. The flexible Emory cloth makes short work of it. I use 100, 200 and sometimes 400.

milkbaby
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Re: Sanding Choils and Spines

Post by milkbaby » Wed Jul 17, 2019 2:38 pm

Note: For choils, I find that merely relieving the edges is best. You see sometimes people round it too much, but unlike the spine where the knife is the thickest, the choil is getting thinner and thinner as you go from the spine towards the edge. When you round out a really thin section like that, it actually ends up putting more uncomfortable pressure on your finger than a flatter choil with the edges relieved.

Ma_sha1
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Re: Sanding Choils and Spines

Post by Ma_sha1 » Thu Jul 18, 2019 8:36 pm

I like it slightly round, not cut my finger wit it

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