wa handle advice

hi everyone, new to the forum and handle making. I've been having trouble with the joints on the buffalo horn. it looks as of there is a start of a splinter or maybe a small bit of air underneath where it is starting to delaminate(see pictures). my guess is that it is from too much heat due to friction on the belt sander. the brass can get rather hot and I'm thinking it is causing the epoxy bond to weaken and allow an air pocket to form.
thinking of using a lower grit belt than the 120 grit I was using then switching to a higher one, also taking more breaks in between sanding so the brass doesn't get too hot.
any other advice or critiques, especially from more experienced handle makers is greatly appreciated and welcomed. thank you.

 

Hi Moonbat
I can only see what you are talking about in images ending 38 and 29 when I enlarge them. I do see it and am curious myself. I have only one knife with buffalo horn, a Kaneshige which is I think an entry level knife, but it does not exhibit any of the defects you show. mine is buffalo horn to wood with no spacer, so I don't know if that is an issue. if the brass heats more than the wood therefore supporting your thought that it is heat related. I know this is of little or no help. but the real reason I posted is to say your handles are beautiful. I'd be happy to have one even with the defects. very nice work.

 

thank you for the compliment! this is mostly just a fun hobby i picked up because i want my knives to look pretty. will probably start selling them so i can buy more pretty wood and support my habit.
I'm fairly certain I just need to be more patient when working with metal spacers.

 

My joints with buffalo horn look similar to yours. No idea why it looks like this really. I was thinking it's because epoxy gets inside the horn (at it's still porous material). I'm using 80 grit paper on disk sander and constantly check temperature with fingers. When it's get too hot to the touch — I know I need a pause.
After 80 grit sander I start hand polish, so heat isn't a problem anymore.

 

hmm darn, i was really hoping it was a problem with my method so i could correct it. those little marks irritate me to no end and i cant get over it. im usually not a perfectionist but they make me want to scrap the entire handle sometimes. I keep my fingers on the brass the entire time im sanding as a temp gauge.

btw the wood I used for the two toned handle is Canxan negro burl
the yellow one is golden amboyna burl

 

Has you tried adding a thin (like 0.5mm) spacer of vulcanized fiber or something similar between horn and metal?

 

When I started out, I assumed they were translucent spots in the horn, but over time I learned that they are heat-related. Easy to see - just overheat one intentionally and they will look uglier... They also show up easier on lighter colored horn and on cow horn vs. buffalo horn. As Moonbat mentions, they are also more likely to show up next to the quickly heating metal pieces - the thicker the metal spaces are, the more likely - at least in my experience.

The best way to avoid them is to prepare pieces well, work slowly and, even more importantly, use belts as fresh as possible and not too much pressure on the belts. As a result, making handles with metal spacers is more expensive because I need more time and I use and destroy more belts in the process. I have also had bowls with cold water next to the belt sander to cool down pieces quickly, but I never felt comfortable doing that, so I limit it to very few occasions. As a first step, I cut spacers as close as possible to the actual size before assembling the handle to avoid having to sand away material which could heat up the whole piece. I also use very coarse belts for the initial sanding-away of the metal, i.e. 36 or 40 grit until I get closer to the actual shape. At higher grits I try to hold the handles at the spacers to control heat and pressure, and I usually never go beyond 320/400 grit on a belt sander with metal pieces - Anton stops even lower, but I find with fresh belts and a very light hand I can go a bit higher. But, in general, that means more hand-sanding, makes is easier to control for heat and keep everything flush. Heat that builds up on a belt sander may also affect metal and horn differently in terms of expanding and contracting, that's why they are more likely to remain flush with hand-sanding. And with doing all that, I still find it impossible to avoid these spots completely. What you show in the pictures, Moonbat, would still pass the 'annoying -because-not-perfect-but-just-acceptable' test for me. However, these days I prefer combining metal spacers with stabilized woods and have moved more toward avoiding them next to metal pieces, nice as they may look. But others may have had different experiences, depending on the material combinations. That said, nice designs & execution, Moonbat!

Stefan

P.S. Just saw Anton's point about additional spacers - definitely a good idea. Thin stabilized wood spacers also work.

 

i have some .25mm spacers coming in the mail that i will try out when they get here and will update when more testing is done.
Stefan, very helpful and detailed reply. in addition to being more careful with the belt and trying the spacers im going to start hand sanding a bit earlier. I AM DETERMINED TO GET THIS RIGHT!!

 

Firstly, lovely work

Brass, Copper heat up fairly quickly so it is something to be wary of when working with them as spacers or liners as it can easily degrade your expoxy.
Definitely don't dunk it in water to cool it down. As @apicius9 said, sharp belts / paper (disk) are a must.
I have seem G10 change colour when it gets too hot.

For WA handles I have found it's easier and faster to shape on a disk, rather than a belt grinder. But You will make your life far easier if your prep work is good as it saves you during the final stages.

If the horn is porous and that is what is causing the issue, try sealing the ends prior to glue up with CA / Super glue. May do the trick.

Good luck and look forward to seeing more of your work.

 

Thank you for the compliment and your reply going to try the ca glue as well next time and see if that does the trick.