# Friction fit saya(s) scratching the blade(s)



## Matus (May 17, 2019)

I guess I need an advice here. I have made just a few sayas so far - from birch and Lime wood - both very nice, clean with straight grain. I am doing the sayas with friction fit and keep getting scratches from finished sayas. I am pretty sure that this is not the wood itself, but some particles that get embedded in the wood. I shape and finish the sayas with combination of belt saw, belt grinder and hand sanding and most likely I get some grains from the sanding paper or belt finding their way inside. Now I can imagine some solutions, but I would love to hear how others are working around his issue.

Thanks in advance for tips and advices.


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## Bensbites (May 17, 2019)

I have seen that too, I don’t know if it is particles in the wood or the wood it self with softer cladding. I stopped doing friction fit for that reason. 

Keep in mind, repeated drying with kitchen towels will scratch blades. 

Even my wooden magnetic knife bars cause some light surface changes to my clad knives.


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## Matus (May 17, 2019)

I forgot to add that the knives in question are monosteel. Yes, cladding would mark or scratch much easier.


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## milkbaby (May 17, 2019)

In my experience, it's very easy to leave contaminating abrasive grit inside when sanding. You could try compressed air then a tack cloth to remove it best you can.

I've seen some makers go to leather, felt, or other material lining to limit the scratching, but then of course the user has to diligently avoid moisture. 

While I still admire the craftsmanship, I personally won't make friction fit saya after making a couple. Too much work with the disadvantage of possible scratches, and I feel a less snug saya with retention pin protects the blade just as well.

Another thing that I personally did was switch to laminate construction with a soft basswood middle spacer that is kinder to the knife edge. These are of course just my personal choices, but as noted, ones that I came to for practical reasons.


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## Matus (May 17, 2019)

Thank you, I will try the compressed air. Yeah, I may stop making friction sayas because of this.


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## BT11 (Aug 12, 2019)

My trick, I rough up the inside of the say with 80 grit sandpaper, and smear a thin layer of clear silicone adhesive where the blade will be. Provides good friction, and doesn't scuff up the blade. Ive also applied a thicker bead where the edge goes on some sayas. 

I have seen a few makers line the inside of a saya with felt. I tried once and the glue soaked through the felt which defeated the purpose of having soft felt.


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## thebradleycrew (Aug 12, 2019)

@Matus: you might try working your way up with fine grit sandpaper on the inside of the saya, finishing at say 800 grit. You didn't say directly, but I'm assuming you stop at a grit below that level?

Another option for a friction fit saya is to create a tighter fit at the thinnest and thickest points in the saya on the inside, specifically the tip and heel/spine. If you create more space in the middle , that leaves less area in direct contact and less potential for scratching. 

Just a few ideas that you can take or leave.


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## pkjames (Aug 12, 2019)

it is always very tricky to have a friction fit saya. If it is done via friction fitting across the blade, even if it is not scratching now, there is always a chance that something can go in and scratch the blade down the track. It is easy to deal with knives with a thick neck (Sanjo knives) as the friction only comes from contacting a small area of the blade around the spine at heel , but it is harder to carve the saya.


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## HRC_64 (Aug 12, 2019)

All of this was too daunting for me to sort thru due to expense/hassle so I still use alot of cardboard 



> Farmer measured the amount of free acid produced by various woods under controlled conditions at intervals up to two years. For all timbers examined, including oak, Douglas fir, Sitka spruce, beech, <<birch>>, obeche and Parana pine, there was a progressive increase in free acid. More than 90% of the acid was volatile and was identified chemically and chromatographically as acetic acid.
> ,,,
> 
> Most metals are attacked by acetic acid, which can cause corrosion at concentrations as low as 0.5 ppm in air. Serious damage can occur through long-term storage, especially in damp conditions...









My understanding (correct me if I'm wrong) is that magnoia is pretty good but not available outside japan.


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## TB_London (Aug 13, 2019)

Carve the inside with chisels, no sanding means no grit to get stuck. If you are sanding you will get shed abrasive embedded in the wood. With a sharp gouge it’s quick work too


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## Matus (Aug 13, 2019)

@TB_London - that is what I am thinking ... after my last experience. The key issue will be to make sure no loose grit from the belts (shaping of the saya) will get inside.


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