||[Apr. 30th, 2010|11:02 pm]
Forging titanium, as it turns out, is easy: get it hot, hit it hard, and it moves readily under the hammer, more like a good quality low carbon steel than anything else. Certainly easier than any stainless or tool steel.|
Grinding titanium . . . ugh. This stuff is tough. It will grind, but even the burrs take some effort to grind off, and removing all the surface scale is going to take a while.
Pictures? Well, I've got to reformat them, but I took some videos. I'll see if I can get them up later.
(edit: actually, if anyone out there likes video editing and would like to make the rough shots viewable, please let me know and I'll put up the raw .avi somewhere.)
Is this some sort of weird alloy?
I was under the impression that Ti absorbs a lot of O, N, H when it hits about 1300C and embrittles.
Well I found this squib
which tells me how I'm wrong. I guess I'm remembering why one can't *weld* titanium except in a vacuum or some sort of inert gas rig.
Yeah, it's 6al-4v, which forges much like low-alloy steel according to the literature. I forged a bit thick in order to allow any nitride/oxide contamination to be ground off. If I can find an effective grinding belt to use, I'll probably be doing a lot more titanium -- I think I like it.
Oh wow, making titanium in a flowerpot
might not be so pointless after all if you can forge it (although not forge weld it).
You may be interested in this guy's site
. He has sections on how to anodize titanium
, and how to make an anodizer
. I learned how to anodize titanium from a costumer at the world SF con in Toronto (94). he would build up fantasy swords with layers of surplus titanium sheet, and then make them pretty colors like green and gold. He demoed using diet coke as the phosphate ions in it are cheap and readily available. He recommended using TSP, but I like using borax instead because it's more environmentally friendly than phosphate and it's a thing that's hanging around most blacksmiths' shops anyway. On top of single color you can do multicolor by doing the higher voltage colors first and then following up with a "wash" of a lower voltage color for the background. For example you could do up a finished blade in a rose color, then do the finish work including the sharpening and then follow up with a nice gold color. Also it's possible to create an "electric paintbrush" where you make the ferrule of your brush a cathode, paint dry titanium with electrolyte and you get color wherever the brush goes. Then do a wash or not afterwards. One problem with this technology though is that it does not wear well. The color is an optical effect based on the thickness of the Titanium Oxide layer (rutile), and anything that gets a lot of wear will polish down to normal titanium color. So you might not want to anodize stuff to sell, but if you have the ability to touch up your own gear, why not? I've had a lot of fun recently buying titanium sporks from REI and anodizing them. If I was of a more merchantile bent, I'd make a bunch and try to sell them at BaitCon ^_^
I have an idea way out from left field. I remember my shop teacher bragging about drilling titanium using common HSS. He said the trick is that when Ti is cut it work hardens, so to remove material on the next pass, you have to reach under that layer and cut through the unhardened material beneath (in drilling this translates to drill slow with a heavy feed). I'm guessing sandpaper grains don't have that kind of reach especially once the belt has gotten loaded up a bit.
I have been told that vikings did not use sandpaper, but rather used a sharp knife edge to make wood smooth. Is it possible to make some sort of HSS "peeling knife" from HSS (maybe something that looks like a spoke shave, with a tool bit in it, or a draw knife), or maybe if you have a shaper you could remove the oxide layer that way.
Actually, the problem is that Ti is too soft to allow the belts to self sharpen -- the abrasive is designed to break as it grinds, revealing fresh, sharp edges. On Ti, it just gums up. Trizact or similar structured abrasives gets around this by wearing down and exposing new grit.
What you're looking for is generally called a sen, a Japanese tool used for making swords -- sort of like a draw knife designed for use on unhardened steel. I'd guess Ti is too hard for it to be effective.