Troublesome Ebonite..

[chriselle]

I got a few 1 meter rods of plain black ebonite from a local producer here in Japan and while the stuff looks good it is a bear to turn. I don't know if it has a higher sulfur content or something but I dulls my tools in seconds. Even the Woodchuck with it's carbide cutters are no match. A couple passes and that facet is dull...and I mean DULL. I realize there probably isn't much I can do but if you guys have any ideas, let me know.

 

[KBs Pensnmore]

Are you able to find out from the supplier/manufacturer its content, otherwise try turning it a bit slower or putting it in a metal turning lathe.
Good luck

 

[bitshird]

Chris, guys have told me that Ebonite, does a number on my carbide, but they've said they got two or three pens from one side, but WOW killing an insert in a couple of passes, incredible. since it's basically a very hard rubber, it doesn't figure to me it should be that hard, or abrasive, but like everyone else, I'd assumed it was the Sulfur causing the extraordinary wear on the cutting edge.

 

[drgoretex]

Well, I'd have to say that I have found the same thing with ebonite. Takes a terribly long time to turn, as I have to keep sharpening. Perhaps not quite as bad as what you are describing, but certainly similar. I will sharpen perhaps 5 times in the course of turning a barrel or cap. Probably 12 times in the course of turning the whole kitless.

Ken

 

[jd99]

Maybe try a different grade of carbide, or a coated insert to help with the abrasiveness (sp?) of the part.


Thats one thing I noticed that no one states the grade of carbide they are selling for the the inserts of these wood turning tools.

There are different grades for different applications, might be benificial to investigate something different to use.

 

[wizard]

I don't know if this is helpful or not...I have a background in chemistry and polymer science (previous lifetime). What I do know is that..Ebonite comes in different degrees of "indentation hardness" which is determined by both sulfur content and degree of "vulcanization"......I would imagine it's availability in multiple degrees of hardness is to accomodate it varying uses. There are differences in Ebonite made from Germany, France, India and Japan. I normally have just used Ebonite from Germany or France. I got some Japanese produced black ebonite from a supplier on E-bay that was hard as rock while turning...to the point I gave up on making the pen..and the remainder of the rod is still sitting in the shop. Doc

 

[chriselle]

Thank you for the responses guys. Well, maybe I can just use this remainder stock for front sections...although with 3 one meter rods...that's a lot of sections..haha. I'm going to contact the supplier to see if he has any other "softer" stock.

 

[chriselle]

Chris, guys have told me that Ebonite, does a number on my carbide, but they've said they got two or three pens from one side, but WOW killing an insert in a couple of passes, incredible. since it's basically a very hard rubber, it doesn't figure to me it should be that hard, or abrasive, but like everyone else, I'd assumed it was the Sulfur causing the extraordinary wear on the cutting edge.

Yes Ken....I was like...What the F.....? The stock I got is only 19mm so there isn't all that much material needed to shave off but I used one four sided cutter for one kitless cap and barrel. All four sides couldn't cut butter after ....amazing.

 

[BRobbins629]

I have another theory (as well as a background in polymer chemistry). Yes, more sulfur and longer vulcanization times make for a harder rubber but in hardness terms I doubt that any ebonite approaches the hardness of metals that are less harsh on the tools. In all likelihood, ebonite contains more than 50% filler material - carbon black and a variety of clays if it is black and a variety of clays if it is colored. Some of these fillers which are needed in the formula to give the ebonite its properties can be very abrasive. I suspect they, rather than the amount of sulfur vulcanization time are responsible for the wear.

 

[wizard]

I have another theory (as well as a background in polymer chemistry). Yes, more sulfur and longer vulcanization times make for a harder rubber but in hardness terms I doubt that any ebonite approaches the hardness of metals that are less harsh on the tools. In all likelihood, ebonite contains more than 50% filler material - carbon black and a variety of clays if it is black and a variety of clays if it is colored. Some of these fillers which are needed in the formula to give the ebonite its properties can be very abrasive. I suspect they, rather than the amount of sulfur vulcanization time are responsible for the wear.

Bruce, So I found out you are a chemist !!! You got me curious...so I looked up some the formulations of ebonite (..and there are hundreds) and it was interesting. ..some of them have silicates, metal oxide powders intermixed between the crosslinked ebonite...increases the Shore hardness scale. Very likely that does take a toll on metal tools. Doc

 

[chriselle]

OK....so...determined not to have 3 meters of ebonite rod just sit here in the shop I decided to try working it again. Well, low and behold I found a way.

Turn the damned lathe speed down !... ALL the way down. I turn everything with the lathe cranked but this ebonite wasn't having anything to do with that. Slow..and it cuts like magic.

So, if you are having trouble turning ebonite, try turning down the lathe speed.

 

[wizard]

OK....so...determined not to have 3 meters of ebonite rod just sit here in the shop I decided to try working it again. Well, low and behold I found a way.

Turn the damned lathe speed down !... ALL the way down. I turn everything with the lathe cranked but this ebonite wasn't having anything to do with that. Slow..and it cuts like magic.

So, if you are having trouble turning ebonite, try turning down the lathe speed.

Chris,
I tried your technique and it worked great!!! I think Bruce is right on target with his theory on abrasive fillers. Makes sense. The higher speeds coupled with the abrasiveness would definitely cause the tool to dull quicker.
Doc

 

[SteveG]

WOW! We have ebonite nerds here, impersonating penmakers