Brian-in-Oz
Retired Swarf Maker
- Joined
- Mar 8, 2013
- Messages
- 137
- Reaction score
- 133
Easy! make it out of titanium.
Hi all - a while back a friend gave me a piece of titanium bar 10'' X .750". Originally it was a hydraulic ram on the Sydney to Hobart winning yacht Wild Oats X1 which is one of the boats he works on. I must have been in an adventurous state of mind today as despite all the horror stories I had heard about machining titanium I decided it was time to put that exotic looking piece of metal in a chuck.
With sweating palms I decided the first thing I would do is attempt to cut the 5/16" X 24 thread. I had some nice HSS taps (mid taper and plug) and set about the task. First drill a hole with a I letter drill. It soon became apparent that this light weight and rather pretty metal is some tough customer. Despite using a liberal dose of tap magic as cutting fluid quite a bit of heat was generated but with a bit of patience and care a hole was drilled without delegating a spare hole in my letter drill case. Next step was to load the mid taper tap in the tailstock chuck and have a go at cutting a thread. Once again it became immediately apparent that this stuff was not remotely related to brass but non the less by repeatedly and very carefully cutting a bit and backing off I managed to get to the bottom of the hole without breaking the tap. I then finished with the plug tap with no further drama.
The big surprise was that on cleaning and inspecting the thread I would have to say that it was one of the nicest looking threads I have seen. Not the slightest sign of pickup, just a beautiful polished looking thread.
So far - so good, now to turn the nut and nose diameters. For this I used a slightly rounded nose sharp carbide insert and cut 10 thou. at a pass. While it was obvious once again that this is tough stuff the swarf peeled off cleanly leaving an excellent finish.
To mill the flats of the nut I ran my mill as fast as it would go and used a four flute HSS end mill cutter taking cuts of .2mm (my mill is metric) and sprayed CRC while cutting.
No problems were encountered and the finish was excellent and the cutter remained sharp. I was sure my ball turner would not take the stress of cutting the rounded nut nose so I did this with a coarse file first progressing to a fine file and finally polishing with carborundum paper.
And so ends my first encounter with titanium, admittedly on a small component.
Does it deserve its horror reputation? - in my opinion no.
Is it more difficult to machine than most metals I encounter? - definitely, but with solid rigid machinery and sharp tools and patience it is quite do-able.
Will I be using more titanium in future projects? - almost certainly not unless it is particularly specified - it is simply very time consuming (not to mention the cost) at least with the tooling most home shops possess.
I guess a bonus of having a titanium propellor nut is when someone asks what my Edwards Radial is made of I can say oh! titanium -uh- and a bit off other stuff.
Cheers all - Brian th_bs
Hi all - a while back a friend gave me a piece of titanium bar 10'' X .750". Originally it was a hydraulic ram on the Sydney to Hobart winning yacht Wild Oats X1 which is one of the boats he works on. I must have been in an adventurous state of mind today as despite all the horror stories I had heard about machining titanium I decided it was time to put that exotic looking piece of metal in a chuck.
With sweating palms I decided the first thing I would do is attempt to cut the 5/16" X 24 thread. I had some nice HSS taps (mid taper and plug) and set about the task. First drill a hole with a I letter drill. It soon became apparent that this light weight and rather pretty metal is some tough customer. Despite using a liberal dose of tap magic as cutting fluid quite a bit of heat was generated but with a bit of patience and care a hole was drilled without delegating a spare hole in my letter drill case. Next step was to load the mid taper tap in the tailstock chuck and have a go at cutting a thread. Once again it became immediately apparent that this stuff was not remotely related to brass but non the less by repeatedly and very carefully cutting a bit and backing off I managed to get to the bottom of the hole without breaking the tap. I then finished with the plug tap with no further drama.
The big surprise was that on cleaning and inspecting the thread I would have to say that it was one of the nicest looking threads I have seen. Not the slightest sign of pickup, just a beautiful polished looking thread.
So far - so good, now to turn the nut and nose diameters. For this I used a slightly rounded nose sharp carbide insert and cut 10 thou. at a pass. While it was obvious once again that this is tough stuff the swarf peeled off cleanly leaving an excellent finish.
To mill the flats of the nut I ran my mill as fast as it would go and used a four flute HSS end mill cutter taking cuts of .2mm (my mill is metric) and sprayed CRC while cutting.
No problems were encountered and the finish was excellent and the cutter remained sharp. I was sure my ball turner would not take the stress of cutting the rounded nut nose so I did this with a coarse file first progressing to a fine file and finally polishing with carborundum paper.
And so ends my first encounter with titanium, admittedly on a small component.
Does it deserve its horror reputation? - in my opinion no.
Is it more difficult to machine than most metals I encounter? - definitely, but with solid rigid machinery and sharp tools and patience it is quite do-able.
Will I be using more titanium in future projects? - almost certainly not unless it is particularly specified - it is simply very time consuming (not to mention the cost) at least with the tooling most home shops possess.
I guess a bonus of having a titanium propellor nut is when someone asks what my Edwards Radial is made of I can say oh! titanium -uh- and a bit off other stuff.
Cheers all - Brian th_bs
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