Stellite vs plywood?

[stephen thomas]

I sometimes make brazed tools (shaper wing cutters, e.g.) with stellite tips; so am familiar with the material and prefer using it (building tools with it) over carbide. But it occurred to me that i can't remember if i've used stellite on plywood edges. The "party line" from one source, which is repeated by every other mention of stellite online, is that it is "not good on glue lines". I can't really remember. Seems like if it was not good, i'd have noticed. But again, maybe never applied it specifically to ply.

Today i made a set of cutters to go in a shaper tool body. to cut a 1-3/4" dia specifically on plywood.
Naturallly i used carbide. One of the cutters cracked after the silver solder cooled, i decided to carry on anyway. No different than a multi-piece edge. Literally.
Then they both showed cracking after roughing out the blanks.
Since i wanted to prove the process to myself (that the method of radius grinding would work) i pressed on.







The cutters would probably get this shortish job done, OTOH I'm probably not going to run them.
I've made brazed carbide tools & sets in the past too, never had a problem, but never quite this wide, either.
One thing that occurred to me is that the carbide blanks were "unknown" and part of an auction box lot. They were probably C6 instead of the C2 i normally use.

So, need to make the cutters again on Monday.
Can go to my stash of C2, and take some precautions in fabbing that i neglected in a hurry on these.

But really, i'd rather use stellite.
Again, the tool will be used to round over (not full bullnose) the edges of 1-1/16" thick micro-lam plywood.
Anyone with experience think stellite would "easily" run 40 ft?

Blanks shown are a little over 2" wide, the radius is 7/8" or 1-3/4" dia.
Multiple cracks in carbide are easily visible. click on photo and then use magnifier /+ icon if not.

 

[dgfoster]

Stephen,

One thing that has always been niggling in the back of my mind running brazed carbide tipped saw blades, router cutters, and milling cutters has been the concern about a piece of the carbide letting go and finding me. I think cutters for wood are often running in the 60mph+ range. I imagine you were out of the line of potential travel. Did you feel nervous running a cutter known already be cracked?

Denis

 

[stephen thomas]

Denis -
These are as completed.
I am "pretty sure" I am not going to run them even though only need to get 40 ft out.

I just really want to limit my exposure to grinding carbide anymore and the question is whether stellite/Tantung G would get the job done on plywood? If not, i'll suit up with all the protective gear and make another set, being sure to use known C2 this time, and take some extra precautions silvering the blanks and grinding them.

smt

 

[gbent]

Store bought tools with that large of brazed carbide use a sandwich with copper between the steel and the carbide. You can (could?) buy silver braze/copper/silver braze laminated filler.

 

[camscan]

Store bought tools with that large of brazed carbide use a sandwich with copper between the steel and the carbide. You can (could?) buy silver braze/copper/silver braze laminated filler.

spot on, I used trifoil.

 

[DJ2]

I found a difference with Chinese carbide vs. German carbide when cutting off 1/8" dia. solid engraving tools. With a diamond wheel, the German stuff took twice as long to cut through.

 

[Conrad Hoffman]

Here's my page on cast alloys. Lots of cobalt in all, so don't breath it!

Cast Alloy Lathe Tools

overview of new and vintage cast alloy lathe tools

www.conradhoffman.com

 

[Rocketdc]

I bought a tantung brazed cutter from freeborn and vaguely remember it was not to be used with glue lines however I never tried it. You might shoot them an email and see what they say.

 

[stephen thomas]

Stephen, the steel blanks could be slit with a saw to give three "fingers" a bit deeper than the length of the carbide

Miland - that is an interesting thought.
Pretty sure an early error was to not cut out the steel blank before soldering.

One of those things where i planned it all in my mind, then got ahead of myself, blanks cleaned, fluxed, pieces aligned, torch in one hand silver in the other and the little voice said "you forgot to bore the steel". The voice on the other side said "screw it. It won't waste that much diamond and you don't really care since your are giving it up after this job anyway". :

Even if the slits partially fill with solder, it should give more than the areas around it.
If these had cracked perpendular to the face, i'd just run them and sand the slight tracks on the work.
But multiple fracturing in layers makes them seem dangerous, and possibly not even durable for 40 ft.

Conrad - good point that all these materials contain cobalt, which is also absorbed through the skin.
I grind most materials with heavy mist, both to cool the tools and to keep the dust down. (Also wear full cartrige mask and rubber gloves). Do you have thoughts on grinding a tipped tool, (perhaps?) as oppposed to solid, with mist?

I like your site resources, but have not visited recently. Today my wife & i went up to Linwood for the tree peony festival, then on to your alma mater for the end of the biennial quilt show, and back down through your town of Canandaigua. Will have to finagle an invite some trip....

 

[stephen thomas]

Several suggestions to use "trifoil" a silver brazing product that includes a copper middle layer, with the silver solder on each side.
This accommodates & cushions the differential stress that occurs between carbide and steel bonded at the same temperature, after cooling.
https://www.jmmetaljoining.com/pdfs-pro ... i-foil.pdf

Naturally, i didn't want to wait around. :^)

Other suggestions included 1.) use C2 since the app is for wood anyway.
2.) slit the steel into 3 fingers, so they can distort as the bonded metals cool.

3.) My own considerations were that I had intended to cut out the steel before silvering the first time, mostly to save diamond. But found everything prepped with torch in hand when the voice commented :" you forgot to bore the steel blanks." I decided, screw it, i don't intend to do this much anymore, so what are a few wasted carats? In retrospect, pre-boring the steel should help, as less area is bonded. (saves silver, too)
4.) Ideally, both the steel and the carbide should probably be pre-shaped for best insurance. But it is just too much nuisance and extra mess.

I did 1.), 2.), & 3.)





The following pix are from the previous cutters. Did same process again, using R & A dresser.




The blade holder keys into the dresser, same as the regular diamond holder, or the rat tail holder.

 

[stephen thomas]

Got side tracked by dinner bell.
No videos, but more pix since you asked.




Climb cutting. 6000 rpm.




Individual pieces are 1-3/32" thick micro-lam plywood, maple faces. Holes are for 1/2" dia dowels.