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Another Epoxy Question

Kevin Weir

Kevin Weir

Joined
May 13, 2020
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Ontario, CA
This one has me stumped. I have a 4 inch thick piece of walnut that had air dried for 30 years. It had a crack in it which I filled with epoxy prior to turning. When I turn through the area containing the epoxy, 1 or 2 passes actually dulls the tool. I mean, it’s Dull and it stops cutting entirely! There’s nothing wrong with the gouge, it’s a new Mastercut 1/2 inch bowl gouge from Oneway with M42 steel. The gouge will cut cleanly through an entire bowl from the same piece of walnut and even from non-epoxied areas of the same bowl blank. But when it cuts into the epoxied area, it’s dull after one cut. I used Chill brand epoxy with a 24 hour cure time. Anyone have any idea what’s happening?
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Epoxy is going to be a lot harder than the walnut. Not familiar with Chill, but other epoxies I can make quite a few passes before sharpening.

Rapid dulling is usually related to cutting abrasive materials.

Did you add anything to the epoxy to colorize it?

is it possible that 30 years of some fine abrasive accumulated in the crack and that abrasive material is dulling the tool?

I would also be suspect of the gouge if it is truly new. Do you have an old gouge to try for comparison?
 
I tried my other gouges just to eliminate that possibility and yes, they dulled rapidly too. I added 2 drops of black dye to the epoxy to make it black. Perhaps added too much? Mixed about 60 mL total. I have about 6 other blanks with varying amounts of epoxy. Now I’m concerned they may have to be discarded.
 
I currently use Zap 15 minute epoxy (https://www.amazon.com/gp/product/B007TUDALA/ref=ox_sc_saved_title_2?smid=A7S7577DAKSIJ&psc=1). However, I can't attest to how easily/difficult is is to cut when its fully cured. I use it to mix with metal powders and apply to cracks or areas I have carved after the second turning of my hollow forms. I wait about an hour and then smooth the surface with a negative rake scrapper. The little "shavings" of the epoxy that comes off are still malleable. I haven't used it to fill a crack for structural integrity prior to turning. Hope that helps.
 
Today I turned another piece of walnut from a different plank. It had a bark inclusion which had been filled with the Chill epoxy. Same dulling effect occurred. I have come to the conclusion that it is the epoxy. Next step is to buy some of the cheaper epoxy from a big box store, try it on another blank and see if I encounter the same effect.
I could always cast a small cylinder of epoxy, mount it in a chuck and see how it affects the cutting edge of the gouge.
 
FWIW, in the information I found about Chill epoxies, there was discussion about sandability, but not about machinability....
 
I use allumilite . You can turn that all day without sharpening a gouge. You can also drop a blank on floor and It won’t crack. Try dropping a pr resin block. The cheaper stuff. Acts like glass and blows up.
 
Last edited:
Glenn Lefley said:
I use allumilite . You can turn that all day without sharpening a gouge. You can also drop a blank on floor and It won’t crack. Try dropping a pr resin block. The cheaper stuff. Acts like glass and blows up.
Click to expand...
Hi Glenn. Where do you get your allumilite?
 
Today I turned another piece that had considerably more epoxy in it than the walnut blank above. No dulling, no problems. The epoxy came off in long ribbons. I’m starting to think that the crack contained sand or some other type of abrasive material. Next time I will blow out even these small cracks with compressed air. Live and learn.
 
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