Earning Your Masters of Exotic Metals Degree at the College of Hard Knocks

Mule Motorcycles titanium exhaust

Mule Motorcycles titanium exhaust

After mentioning what a great education is available at Used Honda University and other DIY training centers, Richard Pollock of Mule Motorcycles describes a recent semester where he studied hard and earned some extra credit.

Here's Richard:

I received a “Masters of Exotic Metals” at the college of hard knocks.

I recently built a very exotic Triumph based on a new Bonneville motor. The primary goal was weight reduction. Starting out with a very heavy motor, it doesn’t leave much to work with in the chassis department. I had basically 100lbs (minus motor), as a goal, while still maintaining somewhat of a traditional looking streettracker styled, street legal bike.

Mule Motorcycles titanium footpeg plate

Mule Motorcycles titanium footpeg plate

So how do you get a rolling chassis, with tank, seat, lights, exhaust, brakes, battery and electrics to come in at just 100lbs? Not easily and certainly not cheaply. The first thought most people have is carbon everything right? That won’t satisfy the “Traditional” looking part, but yes, perhaps there could be some carbon worked in.

The most straightforward way to lighten parts that need the strength or structural integrity close to that of steel is to make them from Titanium. Wow, Titanium. Just that one word instills a sense of awe. The most common alloy bantered about while benchracing is Ti. Have you ever worked with it? I hadn’t, even though I’m a “Spaceship” mechanic by trade, our Spaceships use very little if any at all.

Mule Motorcycles titanium footpeg plate

Mule Motorcycles titanium footpeg plate

So here we go, diving into the unknown and the beginning of my “Practical” education in Titanium. I’ll share some critical lessons that have all been learned the hard way, hopefully saving you from the pain and suffering of enrollment into Ti-Ed. Please note that I’m not a technical expert and the lessons continue!

Lesson One: First, Ti is light. How light? Unfortunately not quite as light as you thought. On the weight scale, steel is heaviest, with Ti at about 65% of that, aluminum at about 50%, Magnesium is at 45% and carbon is just crazy light. So when you figure in the expense and hassles of Ti, remember that it’s the absolute final thing you do to make your machine lighter. For example, I built myself an XR650R Honda flattracker. The bikes are very heavy stock, on the order of 270lbs. I needed to be in 220lb range with 50% more power to also added in! A bet for a breakfast burrito said I wouldn’t make 240lb, so at that point, no expense would be spared. One of the lessons learned was that by modifying a 76 YZ400 aluminum tank, I saved 7lbs over the original monster offroad tank. Cost? About $60.00 or so. Next, I bought every single Ti bolt I could find for the entire bike, not including the axles and swingarm pivot. I trimmed 1.5lbs at a cost of $630.00. Ok, we need to start thinking about cost per pound when embarking on a weight cutting mission. Comprendez? Do everything else first before you purchase your ticket to Titanium-city.

Mule Motorcycles titanium rear axle and footpeg plate

Mule Motorcycles titanium rear axle and footpeg plate

Lesson Two: Titanium is very expensive! Axles, nuts and other assorted parts needed to be machined up by my local neighborhood aerospace machine shop, but they suggested I supply the material. No problem right? Holy crap! I ordered a piece of 1” x 36” bar that set me back close to $400.00 with shipping. The good news is that shipping Ti stock is cheap because it’s so light! I think I ordered maybe one more piece and then turned to “Raw Material” on eBAY. Ok, now we’re talkin’. I started buying remnants in the sizes I could use for $6.00-50.00. At least it became affordable.

The downside is that machining, drilling, cutting or welding all present new challenges, which equate to higher costs. At my local machine shop, the machining costs were about 20% more, plus I had to pay for a lot of tooling. Tap a hole, as in one hole and then throw away the tap. Drill maybe 2 holes and the drill bit is toast. And Ti has an appetite for not just any old tooling, but the really expensive, exquisite stuff.

Lesson Three: If you’re gonna drill or tap this stuff yourself, don’t. Unless you have lots of high quality, sharp drill bits. Personally, I have never successfully tapped a hole in Titanium. But I have broken off several taps halfway into tapped holes, so I’m halfway there most of the time! Drilling Ti requires more pressure than drilling a hole in steel and a much slower speed. If you almost break through and then it gets really hard to drill and you don’t see any chips being created, you just smoked a drill bit. Important point here. If you continue to try and drill with the same bit and more pressure, the material around the hole hardens up like a diamond. The titanium actually starts welding itself to the bit and common sense will tell you that a drill bit with a glob of Ti welded to the end of it doesn’t drill very well. You’ll begin to wish you’d just had the machine shop go ahead and do it. A couple more bits and you’re through!! You need lots of Ti specific drill lube (see lesson 3!). What I do at home is drill halfway through and then let the material and the drill bit cool way down. Then proceed.

Lesson Four: Trial by fire! This is a true story. However, if they find out about it where I work, I’ll deny it profusely and tell them I was just taking some literary license. Anyway, I was at work and during lunch I decide to “Lighten” up a piece of Ti with some .375” holes. I was doing well and was still on the first drill bit. But things were heating up and I was increasing the pressure. I decided to get some lube. It was a petroleum based lube called LPS. The next thing I know, I’m spraying LPS all over the material and some even got on the drill chuck. This was no ordinary drill press. It’s a very big, powerful, expensive one. It matches the cost of Titanium perfectly. What happened next was kind of a rapid fire blur. Lots of pressure, the tip of the drill bit turned red like a nighttime photo of a brake rotor on one of the big Porsches at the 24 hours of Daytona, and then a big whoosh as the lube turned in a giant fireball doing about 1200 RPM’s! Holy F!!!!! The air-hose was attached to another machine and wouldn’t reach anyway, the fire extinquisher was 100’ away, the water bucket for cooling parts was empty and lastly, my heart was about to leap out of my chest, closely following my BOE (bugged out eyeballs!) I blew it out rather quickly and cleaned up even quicker. Ok, I need to find out what kind of lube to use on this stuff.

Mule Motorcycles titanium brake

Mule Motorcycles titanium brake

Lesson Five: Over-expansion. While doing some exhaust work today, I was expanding the end of a piece of tubing to make a slip fit joint. I was doing a practice run on a 3” long piece of scrap material to get the hydraulic/electric expander set correctly. I had the head screwed down way too far initially and when I hit the pedal, the tube went to the point of splitting in about one second. Although, it didn’t just break or split. It split while making a big WHAM sound and shooting a fireball right at me! WTF?

Lesson Six: White sparks! My friend Don, way back in my Air Force days of the early 70’s showed me something really cool one day. If you hold a piece of Ti against a grinder or belt sander, the sparks that fly off are white! Cool! Fast forward about 38 years. I’m standing in front of a 10” wide belt sander contouring a piece of Ti with white sparks flying everywhere. I actually learned two lessons at once this day. First, if you grind on the end of a piece of tubing which fills with these pretty little white sparks, the tube turns into a bright flashlight. Very bright!! Second all the dust from the sparks that lands on your arms or t-shirt create an odd affect. I took an air blower and blew away the dust. My new Porsche T-shirt was destroyed with tiny holes. Conclusion. Those pretty little white sparks emitted from Ti are not just its “Signature”, they’re white because they are white hot!

Finally, after asking around and reading up I’ve discovered that Ti is for the experts. It takes special tools, handling, lubricants and a certain level of skill. I’m getting smarter and better at working with it. If you’d like to read a very good book that has an interesting take on the development of Titanium, I recommend “The Skunkworks” by Ben Rich. They tell all about the design and development/construction of the SR71 Blackbird. It was built with a Titanium skin as well as most of the rest of the plane to withstand 2000 degree surface temperatures in flight!

As Richard's experience clearly shows, learning can be a helluva lot of fun but it's not for the faint of heart. The thing is, after going through this process, he now has a large chunk of practical knowledge he didn't have before, the same kind of knowledge you can get at your own DIY technical institute.

Go ahead, sign up for a class and dive in. Start today!

And welcome Richard as a new contriutor to The Kneeslider! Richard, as most of you know, is "Mule," the builder responsible for the superb street trackers from Mule Motorcycles.


  1. Ian W says

    Wow, sounds like the College of hard knocks costs about the same as my University degree!

    Great post, thanks for the insight. I do my level best to avoid metalwork and stick to clay and fibreglass. Much softer to cut through, but also burn nicely given the opportunity.

  2. Tin Man 2 says

    I had no Idea that Ti was so hard to work with. Very informative and helpfull article,Thanks for sharing .

  3. Lawrence says

    There is no other way to put it.

    Richard Pollock”s trackers are just fookin awesome!

  4. FREEMAN says

    I work with Ti on a daily basis, and to read your story getting acquainted with the material was extremely amusing. Ti is one of those metals that’ll generate a self-sustaining fire. So in the future, I recommend you be very careful grinding and drilling with it. And speaking of drilling, I recommend you use carbide drill bits, drill at 500 rpm max or even less, use lots of lube compatible with Ti use (could accelerate Ti corrosion or catch fire otherwise), and use step drill bits or reamers and a pilot hole. Also, it’ll take a class D (combustible metals) fire extinguisher to put a Ti fire out.

  5. says

    Merlin, assuming you’re referring to the XR650R Honda flattracker/burrito bet, I took a lot of weight off of it! Never did weigh it, but I won a crap load of races on it and doubled the horsepower. In the end, the weight was no longer a factor, proper set-up and traction were the most important factors.

  6. Oldyeller8 says

    I am anxiously awaiting the UnObtanium-Ed course along with an intro in Rubber Cam Lobes.

    Recently did my first welding. Sorry though – Made a BBQ not a bike – and the damn things doesn’t even have wheels!!! But it cooks like a dream. Even doubles as a beer bottle opener for those non-twist off Dutchies!

  7. says

    good posts Kneeslider & Richard

    re: lesson 5

    my h.s. physics/chemistry is getting (uh-hum) rusty, so I could be wrong, but I think you learned the hard way that the coefficient of thermal expansion of ti happens faster than iron (iron may expand more than ti but the expansion happens sooner in ti).

    Temperature dependent

  8. dano says

    We work with Titanium on a regular basis making jet engine parts. There are many different types of Titanium material and they all have their nuannces. When tapping Titanium you need to toss out the standard drill/tap chart. You must ‘shoot’ the tap through in one direction, no cut and back off or the tap will break, the material grabs the tap. After exiting the hole you can back it out in one complete operation. You should use a “gun tap”, two flute with a concentric/coneccentric grind. N.Y. Twist and Clevland Tool know what this is.
    Titanium has “memory” and tends to expand and contract when you use the wrong tooling. H.S.S. tooling is N/G, a cobalt based tool is the best, sometimes prefferable to carbide. When drilling we consider a hole a deep one if it is through a thickness or to a depth of one and one half times the diameter of the drill. (.500 dia. drill, .750 is a deep hole)
    High pressure coolant and a CNC machine are preffered, A water soluble coolant with a high pressure additive in it is the best, straight oil can cause fires.
    There is a ton of information available for working with Titanium but it is sometimes held close to the vest by the companies that have developed it. The new Machinery Handbook does provide some great help.
    I could hold a seminar and class on working with this wonderful material but doing it is the best expierience but you should have the correct tools to begin with or your working against yourself.

  9. says

    As a machinist myself, I can certainly identify with you Richard.
    Titanium is difficult but worth it, One thing I’ve noticed is that it’s frequently used as a material replacement for steel parts. Being lighter than steel and stronger, It is a good replacement but because of that, you can use less of it and achieve further weight reduction.

  10. MacKenzie says

    This contribution is a perfect example of the reason why I read the Kneeslider daily, on an almost religious basis. My experience as a “machinist” was limited to building one-off prototypes (we only got one shot!) as an elec/mech engineer in the film special FX biz; the more skilled guys worked with Ti for very small parts in camera movements. These had to be strong, light, and stiff. Occasionally, we made larger structural parts out of magnesium. We had the odd small fire……. ! But I never knew that Ti was so difficult to drill and tap; my skills limited me to 7075 and stainless steel.

    That Triumph is gorgeous! I’ve owned lots of Triumph powered street trackers, still have one 750 – kitted TrackMaster. Some day would love to have a modern version based on the new lump.

    Great writing and great work!


  11. says

    Heres another Ti-tidbit I forgot about. I have a friend who does beautiful Ti welding. He welded the exhaust on the bike shown here. He said since we were welding up very thin tubing, he needed .045″ Ti weld wire. I had to source it. It was ordered and cost about $140.00 for one pound. The good news is, a pound of Ti weld wire will weld about 16 dozen exhaust systems.

    Tidbit 2- I have a Ti plate in my shoulder with 9 screws and there has been zero maintenance required! So it seems to hold up pretty good as a structural component. The hits just keep on comin’ !

  12. rohorn says

    For threading with a CNC machine, try thread milling (guess what I used to do for a living…).

    While Ti is lighter than steel, it flexs more – check out the elasticity modulus and compare it to steel. It matters – sometimes. That’s why one can, say, drill out a steel axle and have both the same weight and stiffness as the same part as Ti – which is another reason why I think the stuff is grossly misused. Nobody ever won a race because of titanium clutch cover bolts. The only reason I would ever use it is when I can’t run an aluminum due to heat or fatigue (think valves, springs, and exhaust tubing – that’s about it).

  13. Tim says

    Titanium also makes the BEST bicycle frames, in my experience. I had no idea it was so difficult to machine. I understand it is also difficult to weld (need for sheilding etc)?: Anyone care to comment?

    By the way I have a Litespeed mtb frame that is nearly 15 years old, and rides just as well as it did new. Try that with an aluminium one!

  14. Billy B.Tso says

    great post guys!!!! a very entertaining and informative read!
    And the end result is a work of art Richard, top effort! Nice choice of motor too, would almost be perfect if the motor lost a few pounds also, to match the effort placed in the awesome frame work.
    Look forward to reading more about your future projects!

  15. B*A*M*F says

    All I’ve ever done with Ti was make a pendant and a spoon out if some 22 ga. sheet in a college jewelry class. I used so many jewelery saw blades and forming it was ridiculous. On the plus side, it anodizes beautifully and had an iridescent quality to it. Also, the anodized color is determined by the thickness of oxide layer, not a dye. It’s essentially a light interference coating.

  16. says

    Billy B. Tso, The motor actually lost aprox 22lbs! Which gave me a bit of wiggle room.

    Tim, I’ve never ridden a Ti bicycle frame. I had a few aluminum frames(all road) and a few carbon, including an SL2 Specialized. I’ve gone back to aluminum as I always feel like it accelerates better in a sprint and while climbing.

    Rohorn, This bike has ceramic coated Ti rotors, spokes and most of the heavy stuff where Ti seemed to really make a difference. There’s a whole science to weight reduction and eliminating parts all together is the first choice! Like replacing plastic fenders with carbon is a great way to flush money down the potty.

  17. Emmet says


    wow. I’m studying the Machinery’s Handbook right now in school and the lightweight metals get tricky in machining processes (magnesium, titanium, etc.) There’s literally formulas for selecting the best lubricant. But I do not believe that titanium is covered in detail, showing the level of expertise required for a titanium job. Loving your work!

  18. says

    I love these classes. Should I take Advanced Fiberglassing or Titanium Welding for my next elective?

  19. johnny says

    wow, very interesting, I had no idea titanium was so tricky to work with.
    As for the bike, double WOW, one of the best trackers I’ve ever seen! Mind you, I think that about every one of Mule’s bikes I see…I love them, they always look so perfect.

  20. jim says

    Just shows how much trouble and expense some guy will exert to shave a few pounds off a machine. Meanwhile, what if the rider is packing an extra 50 pounds under his jacket? The rider is a significant percentage of a bike’s weight, so going on a diet and losing that 50 would be the cheapest and most beneficial way to go. BTW — that is one fabulous-looking bike! The big Triumph twins never really appealed to me (I’m a fan of the old Meriden Trumpets), but it looks right at home in this street-tracker frame.

  21. says

    Jim, Good point. Although the feeling of tossing around a very light bike vs a heavy bike on the road or track is a feeling that’s worth the money to many riders.

    Who couldn’t stand to lose a few lbs, especially in this day and age. Exercising a ton allows you to eat all you want.

  22. Paulinator says

    This is GOOD STUFF. Just a comment here – I always look at shape first, then materials/processes. Mule, you’ve compared the weight savings of some common versus exotic materials. A small change in shape (cross-section, fillets, radii, etc) can often have a dramatic (exponential) effect on strength, fatigue and rigidity with minimal cost or weight penalty.

  23. rohorn says


    Fun stuff. I was wondering about that disk – I would think that an uncoated one would gall like crazy. Good point about replacing light plastic with light CF plastic – I’m convinced that an awful lot of CF parts are just techno-bling with NO performance benefit.

    I once had a complete rear brake setup with an aluminum disk and phenolic pads for a project – never did mount it.

    I can’t remember who said it – and I’m too lazy to look it up – but I love the saying: Parts left off cost nothing, weigh nothing, and don’t break.

  24. tom says

    One more Ti tidbit – don’t degrease it with chlorinated solvents. They aren’t as available as they used to be, but if you had some tri-chlor sitting around and you dropped your titanium parts it can cause cracks. An aircraft tech told me about a helicopter rotor head that had been put in a degreaser. He had to do a dye penetrant crack inspection & said it was just full of cracks. $$$$ on the scrap pile, but better than losing the helicopter.

  25. Bob says

    I also work in aerospace, but, on the other side of the mouse. I see rejection tags in Ti parts for complex processes like drilling holes, done by shops that do this all the time. An in-law works in the manufacturing side of the house and describes watching CNC machining Ti, cutter submerged in coolant, flashes of sparks and bubbles from those hot spots.

    Someone mentioned Ti as being stronger than steel. Specific strength (strength per weight) yeah, but, absolute strength not really. Ti-6Al-4V typically has an ultimate strength of about 160 ksi (thousand pounds per square inch). That’s pretty pedestrian for alloy steels where 150 ksi is pretty ductile (soft, tough) and can top out north of 200 ksi (pretty brittle). Rohorn mentioned stiffness. Ti is about half as stiff as steel and about 50% stiffer than aluminum. Fiberglass is actually pretty strong (specific strengthwise) compared to carbon fiber and stronger than steel or ti. The problem with fiberglass is that it isn’t very stiff. If you make a part with only enough fiberglass to carry the load, compared to parts made of other materials it will deflect much more easily. Not good for many structural applications.

  26. Gabe says

    What about doing honeycombs? I’ve seen some stuff in a british aerospace museum comparing straight carbon fiber to a carbon fiber/metal honeycomb of comparable strength and the honeycomb was much lighter. Would that work well with fiberglass, too?

  27. tim says

    Speaking of honeycomb, I went to a museum exhibition last year called “The Art of Formula One” Had cars covering all eras (and some hell cool memorabilia from the NZ giants of F1 Bruce McLaren (yes, that McLaren) Denny Hulme and Chris Amon) but the thing that I liked the most was the stuff you could pick up and play with: brake parts, gears from a gearbox, struts. It was designed for kids but picture a bunch of guys in their 40’s going “ooooh, look at how beautiful this gear is” and “Ahhhhh, feel how light this part is”. Anyway, back to the honeycomb: they had aluminium foil honeycomb sections with CF structures built around it. Thats what F1 tubs are built from. Absolutely amazing. But you need a LOT of technology to make it. (computer modelling, and design and manufacture) Hence the rather large investment in the McLaren building in the UK. Absolutely not something you could do in a shed. I dont think so anyway.

    Oh, and all you rich guys need to get your deposits in for the Hulme Supercar:


  28. says

    Rohorn, The brake rotors, front and rear are ceramic coated Ti. Titanium sheet as rolled is not very pretty or smooth/flat. First it’s surface ground then ceramic coated, then surface ground for the final finish.

    In the 70’s, the trick set-up (for light weight anyway), was a Hunt Plasma sprayed aluminum rotor. They were made by Kosman. That would be the same guy that had the XR124 Harley on here a few weeks ago. The problem I believe was that they expanded like mad! I don’t think they were around the paddock for too long.

    While building the Web Surfer Special, I found and purchased one of these rotors. It was for a TZ250, the early having the same diameters as an RD350. So we made a center carrier and everything fit right up. Last November however, I rode the bike in the Norton Owners club of So-Cal annual ride. A very ” Spirited” 80 miles. The brake swelled up, dragged on the caliper and wiped out the rotor and caliper! So both units have been replaced. This time I just used a conventional steel/stainless RD rotor that had been thinned. Works bitchin’, but heavier. Light is cool, but it still needs to be functional. Especially brakes!!

  29. Paulinator says

    There is a huge pool of knowledge in this forum. I’ve heard that carbon fibre will eat aluminum, but not Ti. I’ve also heard that CF lay-up and Ti have about the same coifficient of thermal expansion, making the materials viable in a common structure. Is this all TRUE???

  30. says

    Carbon and aluminum have to have some type of insulating sealer-goo-separator between them or they turn into a battery. They start eating away at each through a corrosion process.

    There are bicycles made from sections of carbon and other sections of Ti. They are bonded together with the combo giving the proper stiffness, compliance and ride characteristics desired.

    I built a Harley for a guy and had a carbon seat shell made. His 500lb(yes!) brother took it for a ride and tflew over a railroad crossing. The seat shorted out the wiring and the seat (carbon is a conductor of electricity), started on fire. He tore thye burning seat off, but a lesson was learned. No 500lb riders please!

  31. says

    Richard, What grade of Titanium is used on the front brake disc and what type of coating did you use? I’ve only tried using grade3 with soft pads, It works well enough but could be better. Thanks for the article by the way.

  32. Greybeard says

    I’ll bet your customer is damned glad he didn’t ask you to gold plate anything!!

    Giddyup Mule!

  33. RyanSTolen says

    fantastic reading. Good writers are hard to come by these days, and you sir, are one of them.

  34. rohorn says


    I remember those – worked on a chopper once that had those on the front – with the old Airheart calipers. The brake I had was to meet the rules requirement and nothing else – it was for a Twins racer project than needed serious weight loss due to the choice of engine (guess which one) – but it was never finished and the frame was cut up & thrown out.

    Remember the aluminum discs with the stainless surface and radially drilled that were made & sold by Pittsburg Performance about 25 years ago? I was told that the reason why they stopped selling them was because the maker of the clad plate freaked out when they found out what they were doing with them – the material was intended for making cookware.

  35. SteveD says

    “No 500lb riders please!”

    Another thing I learned on the Kneeslider. I’ll lay off the M&M’s

  36. FREEMAN says

    @ Paulinator:
    The corrosion issue you mention is true. There is a chart called the Galvanic Series that illustrates this point very well. Basically, it lists the metals or what-have-you in a electrolye environment (like saltwater) and at one end you have the most reactive (least noble) and at the other you have the least reactive (most noble). When two or more dissimilar materials are paired up, the one that is less noble will corrode and the one that is more noble will actually start to galvanize. By pairing up materials closer together on the galvanic series, or by insulating them from each other, you decrease their chance of corrosion. Here’s an example of the chart. Carbon fiber falls under graphite on the galvanic series, which is the most noble material on the chart, with Ti only slightly less noble. Al, on the other hand, is almost at the other end of the chart. Ti and/or CF will corrode Al if paired together without an insulator.

  37. Tony Smith says

    I’ve known Richard, the “Mule”, since pre-Mule days and his fabricating and story telling abilities are second to none. I’m also his boss (ok, no one is “his” boss, I just “suggest” what he works on) at the rocket factory and thought I should share my e-mail sent to him after I read this story.
    “Konnichi wa from Japan,
    In a brief moment of leasure I read the Kneeslider article.
    When I get done wetting myself and laughing, your fired for abuse of company
    Send me Taki-san’s address or web site. I’ll try to visit him this trip.
    “The Boss”

    In a past life I also built racing motorcycles (Tony Smith Racing) and thought I’d share a tidbit about working with exotic materials I experienced the hard way. I worked at Don Vesco’s shop in El Cajon and one night working late on a project the guy (who must remain nameless, but it wasn’t Mule) who was helping me was facing a magnesium TZ750 hub on the lathe. It had stainless helicoil inserts for the sprocket and disc bolt holes. Most of these were below the surface but some not as deep as others. As he faced off to that depth the bit hit the stainless, and started to spark. The machinists out there know where this is going. Needless to say, the sparks fell in the pile of mag shavings in the lathe bed and we instantly had flames to the ceiling. Let me tell you it was BRIGHT in there. I ran to the lathe just in time to see my helper pick up a bucket of water and before I could yell stop he dumped it on the flames. Well mag burns hot enough to separate the oxygen out of water and that just made the fire that much bigger. Fortunately we had dry flame retardant and dumped that on the lathe before the whole shop caught. A good thing as there was no explaining this one. When we were done cleaning up, including our shorts, I looked at my helper and had to crack up. Although the flames never touched him it was hot enough to singe all the hair from his arms, eyebrows, and the front third of his head and perm the rest. He looked like Bozo the clown.

  38. Paulinator says

    I had a similar “thermo” experience doing something low-tech when I was a kid studying at “Hard Knocks”. I was hanging a VW 1600 cc engine I’d just built and I needed a bit of clearance for the 12 volt flywheel. I used a big angle-grinder and stone wheel to over-size the bell-housing of my old crash-box. I made a big pile of Mg dust before I hit a steel bolt. The flash almost etched my shadow on the garage wall.

    @ Freeman, thx.

  39. says

    Several thoughts:

    – it cost more than I thought it would
    – it’s worth every penny
    – Mule is the best at this by far
    – Greybeard’s right….

  40. Chris says

    Reading the story made me laugh my ass off. Ti was a commonly used material at my first machine shop job. Brought back loads of memories and humble smiles. Thanks for the walk down memory lane.

  41. Greybeard says

    Mind, Streetmaster, I do hope everyone realizes I was giving Richard a bit of a tweak there.

    We have history and I have the utmost respect for his talent and engineering skills and I fully acknowledge that I couldn’t have gotten what I did for twice the price anywhere else.

    The fact that he attacked the challenge of machining titanium without an ounce worth of prior history with the material only speaks to his dedication and “WILL DO” attitude!

    So what that 5 minutes worth of Googling would have shown him he doesn’t know his arse from beta transus? Not to be deterred he destroyed $100’s of dollars worth of tooling and material in the quest for perfection!!

    Me thinks there’s titanium in his cranial structure as well.
    Who else would come home from a hard days work work only to listen to us break his chops?

    Must be stubborn. Stubborn as a MULE!


  42. Hawk says

    WOW, I had no idea that working with titanium was so intricate. When I heard that the SR-71 outer skin was made of it, I assumed that’s why it was cheaper to fly sattellites than the Blackbird.

    Now I have a new respect for the folks who built my titanium knees. Also, for the surgeon who put a whacking big titanium frame in my back, secured with ten titanium screws, each 6mm dia. by 7cm long. Is this why the knees cost $30,000 each? I’ll admit that I freaked when the surgeon told me that the back screws were put in with 85 ft-lbs of torque. Damn, that’s what I used to put to my old Volvo headbolts.

    On the other hand, maybe carbon-fiber bits wouldn’t cause so much ruckus at the airport screening point ….

  43. Marneyman says

    Before this article all I knew about Ti was that it made the world’s coolest spork (thinkgeek.com). Now I know I never want to work with it.

    Great article and great comments. I might try that magnesium flash trick just for laughs. If I kill myself I won’t blame any of you.

  44. Joek Hondius says

    Oh and this:
    i know of a project where a Ti exhaust was duplicated in steel.
    The steel version dyno’d less HP, alledgedly because of it’s thermal properties.
    Seemed really far fetched to me, the guys who did it are both highly respected professionals. One engine builder, one exhaust specialist.

    Anyone comment on that?

  45. says

    Ti, stainless, Inconel all do a better job of keeping the heat energy within the pipe. Steel, not near as good. Aluminum can melt and tranfers heat very well and very quick.

    That’s why your example is true and why they don’t make oil coolers or radiators out of Titanium.

    So why aren’t all production exhausts made out of Ti? The new sportbikes DO have Ti collectors which feed into huge, heavy Cat mufflers. But you pay for it! Indy cars, I believe, have their exhausts and especially any plumbing on the “Hot” side of the turbos made of Inconel which keeps the heat in really weel and can hold up to glowing heat conditions.

  46. FREEMAN says

    @ Joek Hondius:
    I would also venture to guess that weight had something to do with it. Pure Ti is just as strong as many forms of steel out there but roughly half the weight. However, I don’t know if the dyno takes that into account.

  47. Bob says

    A dyno only measures engine output and weight isn’t a factor. Mule is probably on the money. At http://www.dpcars.net, Dennis Palatov has been building a motorcycle engine powered AWD track day car/gokart. He has a lot of cash and he had a Ti bicycle maker fabricate an exhaust system in Ti for the car. He connected it to an off the shelf motorcycle carbon fiber muffler. The heat transfer properties of the Ti and the change in cooling airflow to the exhaust led to the car burning up the muffler.

  48. says

    Very cool ride, I dig custom bikes.

    In the SR-71 back shop’s Metal Technology Section, we use to tinker around customizing rides like NO2 Ninjas, with 4130 wheely bars, and scaled down mini drag bikes, all kinds of fun stuff.

    The titanium the Blackbirds use is primarily a BETA 120 / 13V – 11 Cr – 3 Al.

    If you notice in your Machinist Handbook you’ll see that the BETA can be 15000 psi higher in tensile strength than similar treated 6/4 aircraft titanium.

    The material was developed by the Lockheed Skunk Works under a CIA contract. Every time the the Black Jets flew, atmospheric thermal friction would heat treat the titanium make it more resilient, to the pounding conditions of MACH 3 + flight at the edge of space.