Winter trail riding - South March Highlands

Rode about 50km of single track on the fat bike this weekend, including a Saturday night ride at South March Highlands and then a Sunday ride on the same trails. Other than the cold and blowing snow at night, conditions were excellent and it was fast riding. Highly recommended!

This bike is a Norco Bigfoot that I bought last fall. It's been a total blast in the snow. The only mods were replacing the tires (originally Vee Rubber) with the 45North Dillinger front and rear, and swapping the stock joke of pedals with some Saint flats. The Dillingers have a 120 tpi casing that shaves a pound off the bike, rolls and grips a lot better. Otherwise the bike is stock and it's an excellent build for $1500. At some point I may replace the front hub. It's a cone/cup style which is stupid to adjust reliably, and this weekend I noticed it was way too tight. No obvious bearing damage though in spite of some serious abuse in horrible trail conditions over the past few months. Also, the bar grips loosen in the cold and should be replaced with a locking type.

Here's a video of today's ride. Grip was solid. Got a bit tricky when the packed tread narrowed and led to pedal strikes on crust that could rip you off the bike. There's about a 4" sweet spot to ride in. Lots of fun once you get warmed up and the hands finally thaw out.

Lost Iron Mines of Lanark County - Almonte Lecture Series Feb 21

Here's the blurb for my upcoming lecture on the Wilbur Mine.

Friday February 21 at 7:30 p.m.

Almonte United Church

106 Elgin St.Almonte, ON K0A 1A0

If you are visiting the Lanark Highlands just to the west of Ottawa, you'd be forgiven for thinking that it has always been a sparsely populated, rugged wilderness. But if you scratch beneath the surface, you'll find another story that's all but forgotten. 

In the late 1800s, Lanark County was transformed by discoveries of rich deposits of iron ore and other minerals. Demand in Kingston for local iron sources to feed the booming industry there led to the creation of the Kingston and Pembroke Railway. As the rails pushed north, mines and towns sprung up along the way and helped turn eastern Ontario into one of the most active mining regions in Canada. But the boom was short-lived. By the early 1900s the ore deposits proved uneconomical. The mines closed, communities became ghost towns, and finally the rails were pulled up. Dense overgrowth now hides few remaining clues.  

In this lecture, Jordan Smith of Almonte will present the story of the Wilbur iron mine, once the largest iron mine in Ontario. He will share insights gained from exploring the mine site itself, a project he started after discovering some curious gaps in the historical record. 

Jordan Smith holds a combined degree in physics, engineering, and English from the University of Waterloo. Following careers in high tech and the arts, he now works at Deloitte where he advises clients on finance matters relating to R&D. Jordan's many interests include history, archaeology, and teaching which is especially close to his heart. He can often be found deep in the backcountry on his motorbike exploring old trails and ghost towns.

Edit: Over 100 people turned up for my presentation. I heard later that many people were disappointed they couldn't attend. I'm looking into giving the presentation again soon, so if you're interested in that stayed tuned.

Jet Engine - Part 7

This morning I painted and cured the exhaust scroll after grinding off a few spatters and bumps, and filing the flange flat. It turned out reasonably well considering how pitted the original part was.

Then it was assembly time. There's really no secret to this: all the parts go together one way only, except for the shield under the turbine. At first I thought it should cup away from the base of the turbine, since that seemed to match the existing curve better. But after assembling the core I heard the shield rattling around. A quick Internet search showed it should be mounted the other way, curving towards the turbine. This made for a snug fit. The photo shows the correct orientation.

I should mention that it is a good idea to replace the retainer ring on the shaft under the turbine. Since the old one was a pain to remove it was tempting to avoid this step, but under was some coked oil that needed to be carefully scraped out with a dental pick. Cleaning up little details like this can make the different between having the seals last (because of lower friction and the ability for cooling oil to get in there), or blowing them out fast.

A few drops of oil on the shaft and it all slid together beautifully. There were two circle clips in the rebuild kit and I'm not entirely sure what they're for. One could be a replacement for the expansion ring at the bottom of the core, to prevent the brass journal bearing from falling out the bottom. Since there are two replacement journal bearings, it's probably a new clip for each. I just left the original clip in place since it seemed fine. It is unlikely to fail and would be really hard to remove anyway since it's a coil-style and not a circle-clip with ears for a tool.

Admittedly, the washers to hold on the turbine scroll look a little hokey. The originals are too corroded to reuse and are an unusually thick material. I'll have to look for some decent replacements. The seal on the turbine scroll is my main concern with this turbo. I'm not sure how gas-tight it'll be. It wouldn't be good for hot combustor gases to blow out around the perimeter.

The shaft spins nicely and nothing seems to be interfering, so I think things are good to go to the next step: designing and fabricating the combustor. Before I can start that, I need to finish my thermo calculations and come up with a design spec. There are some online tools to help locate the air holes for optimal flow of shield air and combustion air. However, some experimentation will be required before I'm confident to attach the combustor to the turbo.

As you can see, I've rotated the compressor outlet so it's pointing the same way as the turbine inlet. The combustor will mount to the flange I welded to the turbine inlet, and a U-shaped hose will connect the combustor inlet to the compressor. It's looking pretty industrial already and I need to start thinking about how to make this look steampunk with appropriate details for the overall assembly. Lots of brass and stained oak, I think.

Update (April 4, 2014): Work and the need for a MIG welder have delayed my progress. But I promise: more to come!

Jet Engine - Part 6

Welded the flange this morning. Well, actually, Chris Branje (John Branje's son) stick-welded it for me. He earned a case of Bud for his mighty fine job. Check it out:

The procedure was to pre-heat the parts to 800F in the kiln, giving them a good soak before welding. Chris used a nickel flux rod for filler, laying down a remarkably nice fillet. Penetration looked good all around except deep in the scroll crevice where it was hard to reach. We decided to flip the scroll over and just fill that entire area with rod to ensure a gas-tight fit for the flange. The inside of the flange was perfectly aligned and no cleanup there is needed. 

Thanks to the preheating, Chris said the welding was like butter. He's successfully welded cast iron before, but this was the easiest he's seen yet. 

After welding he peened the welds lightly to knock off the dross and I stuck the whole shebang back into the kiln. After re-heating to 800F, I let it cool slowly to about 160F over 6 hours. No cracking observed in the finished product. Oxidation is mild and cleans up easily with a wire wheel on the Dremel. After a thorough cleaning, I'll paint it with the black VHT paint and fire it again in the kiln. 

After Chris finished he let me have a go welding some scrap steel. I had a hard time sparking it up and not getting the rod to stick, never mind dragging a puddle and actually welding. This was my first time trying stick welding. Gives me all the more respect for skilled welders! Hopefully I have better luck with a MIG. 

Jet Engine - Part 5

Time to test that Very High Temperature paint. It's actually a ceramic material, although you need a microscope to read that detail on the label. Prep was pretty straightforward: thorough cleaning with degreaser and water to rinse out all the sandblasting dust, then quick shot of WD40 to displace the water, then another degrease with acetone and then a quick shot of compressed degreaser. The parts came out nice and clean after that, with no apparent oxidation even on the cast iron. You can see why it's called gray iron. Compare the appearance of these parts now with the rusted and filthy junk at the start!

Then it was time to mask and spray. I chose black for the hot turbine parts and red for the compressor. There's not much choice in this temperature range anyway, and these colors should look suitably Victorian. Two light coats and then one medium coat all done within the recommended one hour max, and then into the kiln for a three stage cure at 250, 400, and 600F with a 30 minute soak and cool down between each heat. That red sure looks bright right after painting.

I put the cast iron turbo core and the compressor cover plate under a kiln shelf so it wouldn't be exposed to direct heat from the elements and the little bit of crap that comes off the elements as they expand and contract. I was also curious to see how direct and indirect heating would affect the paint cure. The next morning showed an interesting contrast: the scroll cover which was under the shelf was a nice bright red (although not as bright before curing), whereas the scroll case left exposed to the direct heat was a dull red. Either the direct heat did what it should, or the indirect heat did what it should--but one of them isn't quite right. Thumbnail scratch tests of the three parts showed that the paint is more fragile than I anticipated. Oh well, we'll see what happens when it's really cooking. Hopefully it slows down the oxidation at least a little bit.

The turbo core also took on a blue sheen from surface oxidation due to prolonged heating. Not sure why it would've been so hot for so long: I double-checked my kiln program, but maybe my ramp-down rates were too low. Anyway, this oxidation is cosmetic and should have no impact on the turbo performance since the moving bits are supported by the bronze bearing and an oil film, and there's nothing left to flake off.

Next step was to rig a method of holding the flange to the turbine scroll for welding. I used a scrap of 1/4" plate for a base and then wired everything in place, engraving a groove around the scroll case where it contacts the flange so I can relocate it precisely in case something moves. John Branje, our local expert welder, will attempt to MIG these pieces together using a nickel filler and by peening the welds between passes. Before that I will pre-heat the parts to about 800F in the kiln so there's less risk of heat shock (which can crack the iron casting or weld), and then post-weld slowly cool the parts in the kiln for the same reason. As you can see from my set-up, it'll be easy to lift the parts out of the kiln and onto a ceramic fibre sheet using a long steel rod inserted through the scroll case. One of the benefits of working with kiln-formed glass is I have refractory materials just lying around!

If it all holds together, I'll clean up and paint the scroll case black as well.

The turbo rebuild kit arrived today. All the parts appear to be of high quality and fit perfectly. As a bonus, the replacement o-rings smell like cinnamon oil. Given the kit cost only $78 delivered from Amazon, I should've bought it long ago and just moved on with the project. It's exciting to see this crappy old turbo start to show some promise here! Fingers crossed that by the end of the weekend I can have it all back together and ready to plumb for oil pressure. Then the project really begins.

   

Almonte Riverside Trail now open to Mill of Kintail

After complaining about the dismal singletrack options in the Ottawa area in 2010, I got busy solving the problem and am happy to say that there's now 8km of new trail from Almonte to the Mill of Kintail. The main trail (flagged blue) is about 7km one way, and there's a 700m loop (flagged green) in the middle which goes down to a picturesque set of rapids on the Mississippi River. After cutting the first 4km by myself, local rider Phil Maier did a ton of work to help clear and bench the final stretch to Mill of Kintail. There's now a growing group of local hikers and bikers who use the trail every day.

What next? Well, the plan is to extend the trail all the way to Mt. Pakenham and build a trail centre there. This will require the cooperation of many additional landowners and will take at least a few more years. But having the first phase complete is a big milestone and a great local option.

We are also in discussions with the Mill of Kintail to revamp and open their existing trail network to allow (at least partially) mountain biking.

Group rides are typically Thursday nights at 7:00 pm, starting at the Strathburn St. trailhead. Yes, we ride at night, and we also ride all winter. Fat bikes strongly recommended in the shoulder season and on snow. If you walk on the trail, please use snowshoes so you don't create dangerous postholes for other trail users. Skiing is not recommended because the dense bush prevents good snow coverage over many sections.

Jet Engine - Part 4

Over the last few weeks I've done a pile of work on my jet engine project. It's been on the back burner (afterburner? haha!) for the last few months while I focused on riding, the Wilbur Mine project, and work--which pays for the fun stuff.

Unfortunately, most of the work I've been doing is math: calculating all the thermodynamic transfers from the compressor to combustor to turbine, so I could determine the design requirements for the combustor and develop a fuel injection system. This exercise proved to be quite challenging since it's been about 20 years since my last thermo class, and many important details for the parts I have and system I want to design had to be deduced from a pile of measurements, web info, and educated guesses. I'm not going to go into all the details here just now. For one thing, this blog lacks an equation editor; for another, it would be more useful if I proved out my assumptions before going to all the effort of showing my work.

For now I will say that I found an extremely useful paper from an MIT engineering student who went through the same design exercise as a 4th year project. However, that design used a different turbo than mine and adopted a propane fuel source. Since I want to use kerosene, I needed to recalculate the entire design starting from a different chemical (combustion) reaction, and using a different performance map for my turbo (a Garrett VNT-15 from a VW TDI). The operative concept is calculating the enthalpy of reactants and products through the three stages of compressor, combustor and turbine.

I've completed the calculations and come up with a preliminary design spec. The next step is to design the combustor itself, now that I know the required fuel flow, input and output temperatures, and mass air flow through for my desired operating point.

Meanwhile, I took a break from the math and got my hands dirty. Machining a new main shaft journal bearing has been a real nuisance. I successfully made most of the part to 0.0001" tolerance compared to the original, then took it to a machine shop to bore out the critical internal diameter which includes two steps (the bearing surface) and a recessed area to allow pressurized oil to reach the bearing surfaces. I was unable to make a boring tool fine enough to cut the inside to the required profile, and was reluctant to buy the required tool for about $250. Hence the machine shop. But they screwed up the diameter so now the whole part is junk. Even if I got the interior right (which I'm confident I could), there was the other problem of how to machine an offset circle in one end to accommodate the anti-rotation plug. That would've required a 9mm end mill plus a way to mount it and the part for machining. All told, I was looking at several hundred dollars of tooling.

The easy solution was to order a bearing rebuild kit, which I did for $78 from Amazon. This proved essential anyway, because when I dry-fitted the turbo with my junked new bearing, I discovered that one of the thrust bearings needs to be replaced as well. Plus there's a redesigned oil plate cover in the rebuild kit which is supposed to improve cooling. Bottom line is the kit should solve a bunch of problems and let me move on to more fun things. It arrives next week.

Today's job was sand-blasting all the cast components to remove rust and prep them for painting with Very High Temperature paint. This paint is good to about 2500F and will be applied to all the hot components to prevent further oxidation. The paint is really a ceramic material that sprays on and must be cured at high temperature. Fortunately I now have my glass kiln up and running, so I can cure the paint to 1700F if necessary, which is well above the anticipated ~1100F operating temperature I expect from the jet engine. As you can see, the clean cast iron looks quite different from the crusty lump I started with. This turbo is is in really poor condition--lots of surface corrosion which has eaten away substantial metal--but it should hold together OK. The important bits are there and it doesn't need to take further abuse from a car engine.

The next step was to fabricate a flange for turbine inlet to which I can attach the combustor. This is going to be a tricky operation and it may well fail: I need to weld the mild steel flange to the cast iron turbine housing. It is metallurgically possible to weld cast iron to steel using a nickel filler, but the challenge is keeping everything at the same temperature so the iron or weld don't crack. Cast iron contains a lot of carbon compared to mild steel, which makes it brittle. This problem is exacerbated by the grungy iron of the turbo, which has been soaking up even more carbon from the hot exhaust. The trick will be to heat everything to the same temperature in my kiln before MIG welding it, peening the weld periodically to remove stresses, then cooling the whole welded assembly slowly. This will be a task for John Branje, my local welding expert, who offered to perform the delicate operation for me in my shop.

The flange was cut from 1/4" plate using a combination of angle grinder, jigsaw, and drilling according to a template I made based on the inlet shape. Lots of filing later, it ended up looking pretty good. It'll be important to clean everything before welding, because any contaminants could reduce the ability to weld. I also bevelled the outer edge of the casting to 45 degrees to allow a bit more penetration for the weld bead. Not sure how easy it'll be to get a MIG in there.

Tomorrow I'm going to try painting the all the turbo housing components except for the turbine scroll, which I'll do after it's welded and cleaned up. Fingers crossed that I can pull this off! Otherwise I'm back to square one on this project, and will have to look for a different turbo design.