19 Feb 2019

Okay, a lot has happened in the last couple weeks, though I suppose there’s not a lot to materially show for it. Shown in the picture below is the sum of the work. Seen is a spindle light and speed sensor (made from a 100mm LED ring light intended for cars). Also seen is the black box below the DRO, which contains the mill controls for speed, direction, and jog. Both AC and DC braking are enabled, so when the mill is switched off, the spindle stops in 1.5 seconds. That and other features were found after hours spent combing through the 440-page Hitachi variable frequency drive manual. But, it was worth it, as everything now runs just the way I wanted. Oh, and of course, the mill had to have a Kurt vice. Anyway, with all this out of the way, it means…

The mill can now be used to actually do stuff. First on the list is something that’s been bugging me lately, the alternator mounting bracket in Midlana. For the life of me I can’t figure out why it flexes, as it’s made from 0.25″ steel, but that does appear to be happening. When belt tension is increased, the alternator nose moves in the direction of the tension, throwing off belt alignment. The concern is accelerated belt wear having it break somewhere remote, since it’s a pain to replace. The existing one will be replicated, this time from 0.375″ or even 0.50″ steel.

In the same area of the engine is the idle control valve. The last few times the car was driven, after it’s fully warmed up, idle has a bad habit of hanging up around 1600 RPM for maybe 15 seconds. I don’t think it’s software, and Honda idle control valves are known to stick, so it’s got to be cleaned. It’s Like the alternator bracket, it’s hard enough to get at that I might try the easy way first and shoot some carburetor cleaner into the idle port rather than removing the intake manifold first. We’ll see.

3 Feb 2019

So the mill arrived, with some heart-stopping drama.

Things started out well enough, with the truck arriving on time. The first thing to note is that for some reason, someone decided to sit the enormous 1,676-pound crate (with its integral pallet) on top of a weak and partly collapsed second pallet. That made it tough for the driver to get the pallet jack under it. The there was that he parked the truck pointing uphill, so once on the pallet jack, the crate wanted very badly to roll toward the rear of the truck. I asked if he’d like to turn the truck around, but he said no problem. Okay…

The only thing stopping the entire affair from rolling out the back was him dropping the floor jack and letting the pallet skid to a stop, and we haven’t gotten to the fun part yet.

So as he’s nearing the lift gate, I said that the pallet looked longer than the lift gate. Again, “no problem”, but I wasn’t buying it. As he rolled the heavy pallet onto the lift gate, it sagged, further increasing the downward angle, making the whole thing try even harder to roll off the end. At this point, he had the controlling wheel of the pallet jack about 12″ from the rear of the lift gate, yet there was about 13″ of pallet still in the truck bed. I was sure that we were either stuck, or that it would end up in the street. So at this point, he (now having to stand to one side) had to raise the pallet jack just enough to let it roll a bit more, yet stop it before the pallet jack wheel rolling off the end of the lift gate. He did, stopping it—I kid you not—1/4″ short of disaster. Of course, that meant that there was still 1.25″ of pallet in the truck bed, which was a big problem. The truck facing uphill, the lift gate bending downward, and the pallet still not fully on the lift gate. At this point, he couldn’t let go of the pallet jack handle because it would have swung down, likely causing the entire thing to end up in the street. So then he asked me to lower the lift gate a little. I asked “are you sure?” “Sure.” Ugh, okay, so I lowered it about an inch, and as feared, the front edge caught, causing the entire crate to tip even further towards disaster. He said, “drop it another inch.” Sheeze, okay…. (in hindsight, who’s fault would it be if it fell off? Hmm.)

With a crack and a thump, the 1,676-pound load broke off the leading edge of the bottom weak pallet, and it was finally entirely on the lift gate, and safely lowered to street level—I could breath again. It really was that close to disaster.

Once at street level, there was then the task of pushing it up the driveway, and it took all of our combined strength to get it there, but finally it was in the garage. The pictures show the rest of the story, having to cut away the pallet in order to gain access with the engine hoist. What’s not shown is the 1-2 hours my brother and I spent trying to get the mill onto its stand, which involved using tubes for rollers and literally “greasing the skids.” Then there was removing the mystery preservative on the surfaces, installing the power drives, and, what will take a fair bit of time, wiring everything, including the variable frequency drive.

Oh, and a few may wonder why the stand is so tall. It’s because it puts the work at about the same level as the lathe, which seems right to me. Doing it over again, I might have made it perhaps an inch less (it’s a stretch to access the spindle nut, but since it’s being set up to use the ER32 collet system, that won’t happen often.

Lastly, I took a picture showing a big circular scratch on the mill bed. Don’t know what they did, but since it’s not running yet, it’s my evidence that I didn’t put that there!

More as matters proceed.

30 January 2019

This week had previously been planned as vacation, but coincidently, a minor operation got scheduled late last week. It’s just as well, because recovery has been rather unpleasant. Let’s just say that sitting requires much care, and does involve a donut cushion. I have no idea if it’ll end up back to normal, or if this is the new normal.

Anyway, never being one to sit around, (and the wife out of town), an epic garage cleanup happened in preparation for the arrival of the mill. First was finishing up the mill stand.

Next was an epic garage cleanup, and at the end of several days of non-stop purging, the side yard is a mess. With rain forecast for the rest of the week, not sure how much will get hauled off. From an anthropological standpoint, it was both interesting and disappointing to see what was dug up, things forgotten and buried for 10-20 years—there were even parts from Kimini. Some of the tubing and sheet scraps are so corroded that it, too, will likely end up at the scrap yard. I also have a (bad?) habit of keeping any tubing cutoffs longer than about 2-inches, so there were several very heavy containers of scraps of questionable worth. A line had to be drawn so much of it is going as well.

With the mill taking the place of the drill press, it was moved out from between the “welding table” (in quotes because I haven’t seen but a tiny corner of it in years; it’s a separate cleanup project) and the lathe. That left 15″ of valuable floor space where the lathe could be slide over and the grinding center rotated 90 degrees to free up walking space. The trick of course was actually moving the lathe. I have no idea what it weighs but no luck trying to slide it. I even backed up the truck to the garage and tied a strap to the lathe, with the thinking that I could pull it the necessary distance, but Little Voice in the Head kept saying “bad idea”, so I gave up (the concern being that it would have applied a sideways tipping force, which could have caused it to fall onto Midlana.

I then wondered if a crowbar could lift one end, and a metal rod placed under it to serve as a roller, and then push it. Yes indeed that worked great.

There was swarf, dirt, dust, and who knows what else everywhere, areas which hadn’t been cleaned in decades. (I have a wall-mounted garage vacuum with a HEPA filter; I’m glad it does because I know some of that dust picked up was from the TIG electrodes ground on the belt sander. Some of them contain 2% Thorium, which is radioactive… yeah.) Anyway, two trash bags were filled with just that, and it felt really good to get the entire mess finally cleaned up. I can work in messy conditions because I stay focused on the work-at-hand, but the mess is like a nagging… well never mind. It gets on my nerves after a while and at some point, it has to be dealt with.

Next, the large storage shelving unit was modified per the plan, shortening it 24″ to free up room for the mill (a non-negotiable step, proactively forcing the point that  enough stuff will be thrown to make up for it. So far so good.

In parallel with this, basic tooling for the mill was ordered: a Kurt (of course) vise, cutter bits, collets, and so on. That’s mostly to avoid the wife getting bombarded with many individual boxes arriving at the front door, which only generates troubling questions that I hate to burden her with.

After that, attention turned to the Hitachi WJ200 phase controller (for varying mill motor speed) and how to control it. An order to Digikey provided all the bits, and it was with some irony that I thought “a mill would be really handy to cut out and and drill all this.” This box contains a tachometer and even a cute little calculator to determine cutter speed. In addition there are direction controls, speed, jog, and emergency stop. Of course, it’s not complete without a self-peeling label; that’ll get dealt with at the same time the other controls are labeled.

Lastly, picked up some heavy wire and a fuse box and cut-off switch in anticipation of wiring the beast. We’ll see if the mill comes with a 115VAC outlet (it runs on 230VAC). It’ll be needed for the tach, DRO, and future lighting. Anyway, I don’t get too excited very often, but I feed like Ralphy in the movie Christmas Story when he realizes he’s getting the Red Rider BB gun. Expect more pictures soon since it’s scheduled to be here in about 30 minutes :).

19 Jan 2019

Something big and heavy is headed this way. Yeah, a mill is half way across the country, hopefully one that I won’t think about upgrading for a very long time.

Some background: I’ve gone back and forth on getting a mill for decades, weighing the small (which fit well into a crowded garage) and low-priced import bench mill/drills, against knee mills, and those against enormous, stout, and very used Bridgeport-sized machines. Long story short, I wanted the impossible: a small, high quality, inexpensive, and reliable machine—it doesn’t exist. Proponents of Big American Iron, who always seen to know of deals nowhere near me or deals I missed, insist that anything short of US-made machinery is junk. As is written in the book, if this machine was in a factory where time is money, I might agree with them, but that’s not me.

Buying an old, well-used large machine is not an guarantee of success, and I don’t know what I’m looking at. I get the point about them being more rigid, but that doesn’t guarantee accuracy or repeatability if the ways and/or bearings are shot. The big picture purchase price includes fixing the worn parts (who’s going to make the repairs and what does that cost?). Buying something used means looking at it in person, and most are far away. Then there’s tax and the expense of moving a 3000 lb machine to where I want. Since I don’t have the space for a full-size machine anyway, that doesn’t matter, narrowing the choices to smaller (non-domestic) units.

So many times I nearly bought a bench-top Chinese mill, figuring something was better than nothing, but I just couldn’t. There are so many negative posts about them that I figured there has to be something to that and they should be avoided.

There’s another aspect of this as well, at least as important as the machine itself. Due to the expense, this needs to be a one-time purchase.  I don’t want to risk spending $$$$ on a beat-up or low quality machine only to find out it’s terrible, then have to explain to the wife why I have to dump more money into it, or worse, get rid of it for half what I paid, and then spend double that to get a good one. I ended up compromising between American and Chinese and went Taiwanese. The mill is available in several versions: switchable belts, variable speed, and single or 3-phase. The variable speed version is mechanical, meaning that the speed is set by an adjustable-radius pulley. I’d have gone for that one but it’s $800 more and has a lot of moving parts. Because 3-phase is also available, however, a variable-frequency drive (VFD) can be added, resulting in a much wider speed range, more torque, and it’s also much cheaper, but does require substantial setup. The manual for the VFD alone is 98 pages of dense settings, so there’ll be time spent getting that going, and making a small box containing the controls (speed, fwd/reverse, start/stop, and bump).

The unit is basically a baby Bridgeport and weighs 1500 lbs. so I don’t want to move it any more than necessary. Also, being a baby Bridgeport means that at normal working height, the table is (said to be) fairly low for anyone taller than maybe 5′-8″. For those reasons, a wheeled stand will be made to adds roughly 7″ of height. While it’s tempting to go higher, the thought of having that much weight that high up makes me nervous. The large iron-wheel casters will give it mobility, and it’ll have three (yes, three) leveling pads. The thinking is that four pads won’t spread the weight evenly; there’s always going to be one that has more, less, or even no(!) weight on it, distorting the machine base to some degree. Yes, having three is less stable, but the idea is to crank the pads down so that they just remove weight off the castors. That way, if there’s ever any tendency to tip, the wheels are there to stop things. The plan is to use the engine hoist and lift it off its pallet, straight onto its stand, where it’ll live from then on.

Before it arrives, there’ll be a massive garage cleanup, pulling out everything and probably tossing out or giving away a bunch of stuff. The final layout will probably be slightly different than the drawings from the last blog entry. I’m also going to try something which may or may not go well, as the new layout requires a slightly smaller storage shelf. The one I have is huge, 8′ high, 8′ wide, and 2′ deep, and heavy duty. I just hate to throw it out and then spend more on a smaller unit that probably won’t be as good. The plan is to disassemble this one, cut the frame down 24″, and reassemble it. Either I’ll congratulate myself, or get pissed if it all goes wrong or takes too long. We’ll see.

Lastly, I ordered a manual mill because I can’t justify the expense of CNC. Plus, some of them don’t even have handles! About the only thing I think I’ll miss is the ability to mill curves or circles, but again, the number of times that’ll come up will be few, and virtually everything I make is a one-off, nothing requiring “production”. Because, if I just have to do something requiring a CNC, I know a buddy with a $25K machine 🙂

31 Dec 2018

First off, happy New Year!

So having just reached a big age milestone, a thought bouncing around is, “what am I going to do with my time if/when I retire?” The telescope is useful in that respect because it’ll be something to do when I don’t have to worry about getting up early for work. There’s also a growing itch to start planning for a better-equipped shop where I can make whatever strikes my mood, retired or not. The lead contender right now is getting a mill of some sort. With a mill and lathe, just about anything can be fabricated. The lathe has been indispensable, but there are many things that only a mill can do, and without it, quality suffers. Take drilling several accurately-placed holes…

One of the most annoying things that’s been a bother for, oh, forever, is the drill press—the bit “walks”. One of the worst examples happens when drilling holes through square tubing. Mark one side accurately, drill that hole, and then, “since it’s accurately located, I’ll just continue drilling through the opposite side”, instead of flipping it over, measuring a second time, and drilling that hole separate. For whatever reason, the drill always emerges off-center, enough that on suspension brackets on the car, the part had to be tossed out. I know what you’re going to say: center-punch the hole (I do), use a center drill (I do), don’t bear down on it (I don’t), and check that the table is square to the arbor (it is). It may be radial play in the drill press arbor, or maybe all drill presses do this to some degree. It does it even with single holes as well, I can watch it walk slightly as it initially starts to bite. It’s okay for ordinary drill work, but not for anything requiring precision.

In addition to accurately locating holes, a mill is perfect for cutting accurate slots (instead of drilling holes and using the jigsaw to connect them, which is hard or impossible in tubing), being able to face blocks of metal and know it’s flat, and on and on. And finally, closely related to accurately locating holes is having a Digital Read Out (DRO); once you use a lathe or mill with one, you won’t want to go back. DROs also have built-in smarts for things like tool diameter offset, locating holes spaced evenly in a line, or X number of holes on a diameter. Sure, placing holes manually has been done forever, but the DRO is such an enormous help, it’s also on the list.

This brings up the old problem: where does it go? My “shop” is confined to one half of a two-car garage—with both cars in the garage, which makes working on anything far more challenging. Backing out the cars only helps temporarily since the large equipment stays put. Because of this, adding anything to the shop is a struggle, and especially a mill since a 30″ bed typically needs about 72″ total lateral space due to it moving both left and right. Because of that, its envelope is best suited to a corner, if I had one. Messing about on the computer with paper dolls produced these floor plans. The second one fits better, but counts on the mill bed to project under the band saw table; hopefully that’s not wishful thinking. Regardless, it all starts with a big cleanup, as there’s a lot of stuff taking up space but probably isn’t worth keeping around. It also means giving up half my storage space, but it isn’t that bad since 3/4 of it has sat unmoved for years.

The proximity of the band saw to the grinding center works since the grinding center is lower than the band saw table. As for what mill I’ll end up with, who knows. It all depends what pops up, and while everyone always says to get a used Bridgeport, they’re so old, tired, and huge, that getting one up and running could be a long and expensive endeavor, one I’m not really wanting to get into now. The reality is that it’ll probably be a smaller bench unit, but we’ll see.

9 December 2018

Some updates:

 “Why has it been so quiet?” While Midlana builders continue to make progress, and I keep a close eye on them for support, I haven’t been driving my car much. Why? It’s because I’ve been distracted by a number of things, including telescopes. Back 25 years ago, I built a 10″ f6 Newtonian, used it a while, then got distracted by, of course, cars. Fast forward to now and it’s been sitting in the garage this whole time under a tarp. With the grandkids growing, my interest has been rekindled, but the mirror is in sorry need of being recoated. Me being me though, I see it as a chance to built a larger one, and of course one thing leads to another…

Speaking of being distracted, this weekend was a trackday at Fontana and for several reasons I didn’t feel like going. My brother went and, well, now he knows how I felt a couple years ago. He went out for one session and all was fine for about 20 minutes, then the LS-3 started running rough. The water pump/alternator belt had broken and the engine overheated. No problem, he had a slightly shorter spare and installed that. Went back out and things went from bad to worse. The slightly shorter belt apparently bottomed out the tensioner, overheated the bearing, and the pulley disintegrated, and as it flew off, it took the drysump belt with it, so in about two seconds of running without oil pressure, the engine was junk and his day was done. If there’s a good side to this, it’s that an brand new LS-3 with a factory warrantee is “only” about $7000, and the external oil lines, drysump tank, and pump, are fine, ironically because they failed first. He’s bummed, but not as bad as when I blew up my engine!

21 Nov 2018

Okay, it’s that time of year again. If you or someone you know is planning to get the Midlana or Kimini book, now’s the time to start monitoring the printer’s site, Lulu. Between now and Christmas, they typically offer varying  discounts, sometimes quite a bit, but I make no promises. It’s highly recommended to check with them everyday as discounts change frequently.

And yes, I’m still around, just distracted by other interests at the moment, but don’t worry, I visit the Midlana Builder’s Forum every day, and I shall be back!

15 October 2018

I’ve been catching a bunch of abuse about not posting… I didn’t know you cared so much!

After getting abuse for posting non-Midlana material, I thought, okay, I won’t, which has led to the aforementioned periods of, well, nothing. I haven’t posted because I feel a bit guilty about not having anything worthy. There are a couple track events coming up, but they’re scheduled out far enough that registration hasn’t even opened yet. There’s also a Laguna Seca event, and while part of me wants to go, I’m too afraid until the car has wings. Why?

I used to drive my old Datsun 1200 at that track and loved it, coming up over the rise past Start/Finish, with the car getting just a little light as it crested the hill and the track curves left. It drifted over toward the right edge of the track somewhat, but no problem.

Fast forward to running the Mini there, which had probably 3X the power/weight. The first time I crested that rise I remembered thinking “oh crap”, because I was carrying way more speed and at the same time, the front end got really light, so the car floated way over to the right edge of the track and there was nothing I could do about it (lifting abruptly can cause a spin). After that “clincher”, I had to let off slightly as I got to the top of the rise so that weight transferred forwards onto the front tires, allowing it to turn.

Fast forward to now, where Midlana has 2.5X the power/weight of the Mini, with even less weight on the front end. Unless I let off, probably a lot, before the crest of the hill, I worry I could do a “Mercedes Backflip” (jump to 0:32). Could that really happen? I don’t know, but suspect Midlana would be at around 120 mph at that point, and with no down force at the front and air getting under it, so I don’t want to find out. So, wings are in order before running there. I’m not entirely imagining things. Two friends, after hearing my plans for the weight and power of Midlana back during the design phase, staged an intervention, saying that they seriously recommended I not track the car without wings, especially if there are any rises or drops.

Another annoying issue with Laguna Seca is, of course, the sound limit, which is 90 or 92 dB. Even some OEM cars struggle to reach that, and I have no idea how loud Midlana is at 50 feet. Yes, it’s got a muffler again, but 90 dB is really low. I’d hate to pay the high track fee, drive the 450 miles there, only to get black-flagged after a couple laps for sound (which did happen with the Mini).

Back to wings for a moment, my brother found another source of extruded aluminum wings, these being about 50% larger chord than the ones I already have. Haven’t decided to switch to these for the main elements, available from Nine Lives Racing.

14 Sept 2018

The hoped-for car event – the Virginia City Hill Climb – was indeed cancelled, the rumor being that they were unable to obtain the necessary city permits. I’m skeptical that next year’s event will happen because once a city starts weighing the liabilities versus benefits, it’s a small step to permanently cancelling the whole thing. Guess we’ll see.

Was going to take the car out and glanced in the engine compartment, only to see that again, the alternator bracket broke. As some of you may recall from earlier diary entries, this has happened several times with both my bracket and a commercially-available part–there must be some really nasty resonances going on. My solution, like last time, was to add more reinforcing. Eventually the failures will stop, or another unit will be produced out of much thicker material.

During repair, one thing crossed my mind that might not have helped things: I may have dunked the hot bracket in water to cool it off after welding. That’s a great way to harden metal–making it much more brittle. This time I let it air cool so we’ll see how that goes.

 

26 August 2018

I was going to add an update, but after checking the previous entry, it says pretty much what I was going to write: being too warm to work on the car, and that I visit Midlana Builders’ Forum several times a day. The only new development is that there’s a big-deal driving event coming up, but as of right now it’s unclear whether it’s going to held. More as the time nears, or maybe I’ll just drop the video after the fact, hopefully with the caption, “It went well!” 🙂

 

24 July 2018

Ugh, too warm and humid to be do much, but I visit the Midlana Builder’s forum several times a day. Progress is being made on several builds there, but as warned of in the book, Life gets in the way now and then–it’s just how it goes. Several of the builders are getting closer though, and hopefully that’ll ignite some urgency in the others, hah.

Speaking of motivation, I keep getting told that I don’t promote myself, the car, or the book enough. I understand, and even agree, but it’s because I really dislike pushy ads and salespeople, so I don’t like to do it to others. Nothing shifts me to the opposite tact faster than someone pushy selling something. I had a guy  selling a bottled water service show up at the door, and when I opened it, said “uh oh.” For a second, I thought he was going to take a swing at me – he got really angry. I was curious how he planned to transition to asking for money, or maybe he planned to demand it. I suspect he realized no sale was going to happen and kinda went off the rails after that… but I digress.

So yeah, I do plan to do some promotional stuff, more shows and videos – when it cools off, which around here is October or so. There’s also all the other stuff: cold air inlet, new engine cover, wings, and so on.

16 June 2018

Finally swapped in the Inconel turbocharger mounting studs. Hopefully this stomps out that failure mode for good.

I also had the pleasure of again meeting Martin Waide at a dinner party, ex-Lotus engineer from back in its heyday.  To talk to someone who worked for Colin Chapman himself,  and with Graham Hill and Jim Clark, is just, wow, expanding my world while at the same time making it feel a lot smaller. It’s like finding a little window through which to peer back into history, marveling at the golden age of racecars.

He asked many questions about Midlana and not unexpectedly, surrounding guests rolled their eyes and moved away as we went into suspension design. Since car design is such a niche, I don’t discuss it much because I know that it’s not at all interesting to most people, but, get me in the same room with someone who works in the field and off I go.

I’m going to meet up with him again so that he can check out Midlana; not as “look what I did” but to get a real engineer’s perspective on its design.

7 July 2018

Still here – building a cover over the pond filtration and wiring it with proper GFI outlets instead of the spider web of extension cords I had before. That’s done, but work on the car is postponed due to the first heat wave of the season; it’s currently 101.8F outside and high 90’s in the garage. Just before dawn it was 75F, hah.

On the car, the cold air (hah) intake, wings, and engine cover remain to be done. There’s a driver’s school in September which got my interest because they claim they’ll be running a large-diameter wet skidpad, something I’ve always wanted to run Midlana on (though it means me and the car getting drenched). With all the recent changes (engine, turbo, tune, transmission ratios, differential upgrade, shock settings, and new tires), Midlana’s capabilities cannot be  legally and safely tested on public roads. I say they “claim” they’ll be running it because having water trucked in for the purpose is reportedly around $800, so I want to make sure they’re really going to do it before signing up. An inquiry was sent but I’ve heard nothing back – what a surprise*.

Other odds and ends: Adding the engine tray has aerodynamic advantages but carries with it other consequences. The most striking is that both oil and coolant temperatures increased roughly 4 deg C after adding the undertray, so convection cooling through the engine compartment was measurable. I imagine it’ll be even worse once a new engine cover is installed because the only cooling air will be coming in the side vents (the right-hand vent is currently non-functional but will be cut open). There is some concern that convection and ram-air effects may not be enough to keep things under control, so Plan B is being considered: an engine compartment cooling fan. I remember reading something interesting about the development of the McLaren F1, where they had similar engine compartment temperature issues. The most interesting aspect was where they mounted them: flat on the floor, sucking air upwards into the engine compartment. This had the double effect of moving air in the direction it wants to go anyway (hot air rises), but most importantly, lowered the pressure under the car by a measureable amount, thereby increasing downforce (or decreasing lift) at the same time. That’s pretty clever. The downsides I see are that dust and dirt kicked up by the front tires is likely to get sucked up, plus, the highest ambient temperatures is located closest to the ground. Granted, it’s (probably) cooler than the air around the engine, but I’m not sure whether it would work as well here in Southern California as it might at McLaren’s home of Woking, UK! Effectivity aside, finding space for it could be a challenge, as there’s just not that much open space anywhere in the engine compartment – whoever designed this didn’t oversize things much!

*This is a continued irritation with me, vendors that sell a product yet make it difficult or downright impossible to give them money. I’m currently designing a new pond filter which uses “feather rock”, a volcanic stone with interconnected pores. We have a local distributor of the stuff and I’ve called or walked in four times now, trying to get them to tell me if they can get the stuff – I know they can since they already sell the boulders, which come from the same mine, but I want the 2″ stuff, but the vendor just won’t answer my questions. As a last try, I’m contacting the mine directly and will ask them if they can kick their local distributor in the nuts to make them answer me. Best of all would be for the mine to offer and sell it to me and ship it with the boulders next time they make a shipment to my local outlet, then I pick it up there. I would enjoy walking in and asking for status, and after they give me another non-answer, I say “I’ve done all your work for you; here’s what’s going to happen.” Apparently business is so good these days that vendors just don’t want to bother with special orders – fine, but they could at least say so!

18 June 2018

Had a brief dream of backing Midlana off a trailer and realized there’s a problem, in real life as well – that unless the angle is very mild, there’s a fair chance the diffuser will drag. Have to take some measurements before that happens.

On a related note, I found an unintended airflow experiment has been going on. Back when I replaced the turbocharger studs (more on that in a moment), the turbo oil feed line and feed adaptor had to be removed. It leaked a little and dripped onto the diffuser near its front center. Because of the way the diffusers attaches, some of that oil ran to the forward edge and got caught up by the air flowing under the car. The cool part – which looks better than the picture – is that the air flow remains well attached as it flows aft. What’s hard to see is that near the front edge, the air flows in and sort of “funnels” into the center channel of the tunnel, showing that the strakes are working as well. Also, along the top edge of the picture, you can see how the air flowed up onto the frame/Gurney flap, which would be expected if it was doing its thing. Good.

Regarding the turbo studs, after doing some more reading and getting some helpful hints on the Midlana Builders’ Forum, it was decided that they’re being replaced again, with the only type of stud that won’t stretch under high heat – Inconel. Actually ordering them though was a bit of a drama. For whatever reason, they’re fairly common in the aftermarket – in Australia – but not so much here. Testing the waters, I found they wanted about $50 shipping for their $50 parts, so no go there. In short, they were found domestically in a somewhat-surprising-but-shouldn’t-have-been source, Mazda. Seems the factory had such serious problems keeping their turbos attached to the second(?) gen RX-7, that they use Inconel studs. Thanks somewhat to mass production, they’re “only” $12 each, but hopefully once they’re in, that’ll be the end of that.

As an aside, a vendor in the US advertises “Inconel” studs, but reading the fine print, it turns out they’re actually “Incoloy”, which research shows isn’t the same thing. The vendor tried convincing me they were and that Inconel is just a brand name of Incoloy, yet research seems to indicate that Inconel has more nickel in it and is quite a bit more expensive (less profit). We use the material at work for really high temperature applications and use Inconel and nothing else, so there.

Lastly, if someone tries selling you fasteners and claims they’re Inconel, a simple test is that they will look like ordinary steel (not stainless) but are non-magnetic.

9 June 2018

I know how much you guys just love it when I post non-car related stuff. This year a couple of hawks had babies in a nearby tree and have been visiting the yard, looking for mice, lizards, and gophers. Usually I don’t have the good camera handy and by the time I do, the moment’s gone. This time I got a couple really good shots; I like the first one because of the glint in his/her eye, and the second one, I’ve definitely been spotted!

 

8 June 2018

The aluminum strakes were swapped in; notice how the aluminum end plates are now tucked under the body panel instead of on top. Because it’s cantilevered out behind rear axle centerline, it means that its vertical motion is mechanically amplified. I knew this and plan to trim back the strakes if necessary, and it didn’t take long to learn it might be. Backing out the car with the diffuser for the first time, when it rolled from our slopped driveway onto the level street, the rear suspension compressed just a little and I heard a brief scrap. I couldn’t help but laugh that the new diffuser had lasted all but 15 feet before being scarred. If this happens more frequently, it’ll be trimmed.

After finishing the diffuser, I happened to glance at the engine – never a good idea when in a good mood – and spotted that a stud holding the turbocharger had backed out. If that had been it, I wouldn’t be telling you, but it turned out that two were loose, with the second one being a pain because the turbocharger compressor has to be removed to get at it – you may remember the big Circlip pliers bought just for this. Sigh, when one thing gets fixed, it always seems like something else pops up.

New locking studs and nuts were installed and we’ll see how they last. Drilled-head bolts were not used for two reasons. One is the tight clearance, it wasn’t certain whether they could even be maneuvered into position to drop into the turbine housing mounting holes. The other reason is, being bolts, there’s a fair chance that the threads will get frozen in the stainless exhaust manifold, possibly breaking during removal. For now I want to stick to studs and see how they hold up. If they loosen again, safety wire will probably be involved one way or another. Stainless fasteners were not used because they thread into a stainless manifold. I learned the hard way – several times – that screwing together stainless parts is a recipe for disaster. Even spinning them together by hand often results in the metal galling and basically welding itself together. That said, there is a new stainless alloy that would be great in this application: Nitronic 60. The problem is that it’s so new, bolts made of it are really hard to find. Most vendors who handle it just advertise, “we can make whatever fasteners you want out of this material”; yes, I’m sure they can.

Let’s see, what else… wings. Based upon the references regarding diffuser design, placing the rear wing above the diffuser outlet makes a large improvement in downforce, so that’s the plan, but there are consequences though. Much like how the diffuser’s proximity to the ground is mechanically amplified by being behind axle centerline, so too is the downforce provided by the wing. Given how fast the car is, there is some concern that with a rear cantilevered wing, cresting a rise at high speed could allow enough air under an already-lighted front end to lift. For that reason, I think it’s wise to build both front and rear wings and install them at the same time. Hopefully the front wing will produce enough downforce to keep the nose planted.

In other news, one quirk of this WordPress blog template is how it arranges posts. First, they’re always in descending order, meaning that in order to read a multi-entry chronology, you have to read from the bottom up. That’s not a big deal, but it’s got another quirk of how past some number of posts, it places these additional entries on a second page. If you don’t notice the page selection buttons at the bottom of the blog and just start reading from there, you may miss entries hiding on the second page. I just changed the maximum number of displayed blog entries from “10” to “20”, so hopefully hidden entries are no longer an issue.

2 June 2018

Had the week off so between honey-dos and being on-call, the diffuser was built. As background, the vertical strakes were going to be aluminum, but later, because there’s a fair likelihood that at some point they’ll drag on the street, I switched to HDPE (high-density polyethylene) because I had it, and because it seemed like it would wear more gracefully, unlike aluminum that would bend and stay bent.

Having made the decision to go with “wearable” plastic, the vanes and end plates were initially going to extend lower, such that there’d be only 2.5″ of ground clearance. The idea was that they’d “self adjust”, but after thinking it over, that seemed like a recipe for disaster. Images of having the leading edge(s) catch on something and having the entire assembly pulled off the car didn’t seem impossible. For that reason they were trimmed back so they’re even with the bottom of the car. Anyway, on with the pictures.

There was an aspect of HPDE that I casually considered, that it’s rather heat sensitive. Since there’s a lot of air flowing past the exhaust where it exits into the left-most tunnel, how hot could the air really be? The answer is illustrated in the last picture – “hot enough” (and this was a casual drive, I imagine on-track I’d be dripping melted blobs… sigh – they’ll be replaced with aluminum.

I’m sure you’re wondering whether the diffuser works – good question. My imagination thinks so*, and I can offer that leaves fly up behind the car. But, sometimes leaves flew up behind the car before. My thinking is that it can only improve airflow and at track speeds, will very likely be doing its thing. Oh, and the rear wing will be placed above the trailing edge, which enhances diffuser flow even further. There’s simply no easy or safe way to test it out on the street.

* Of course, after I change the oil on a car, I swear it runs smoother, so there’s that…

26 May 2018

Over on the Locost forum, someone built a diffuser using 1/8″ (3mm) ABS sheet, doubling it on the strakes. I’ve got some left-over black 1/4″ (6mm) HPDE sheet which might work well for the strakes due to being potential wear items. I’ll have to make templates and see if there’s enough material on-hand. Given how diffusers work, it’s tempting to extend the end plates lower than the floor, though that makes them the lowest point on the car…

20 May 2018

Worked on two projects: the cold air intake and the diffuser.

Unlike how I normally do things – scratch-building everything – this time I wanted to see if I could find something “off the shelf” to serve as the air filter enclosure. After wandering around half a dozen stores, a stainless double-wall ice bucket (complete with woven bamboo weave) looked “promising”, mostly because nothing else in the kitchen sections was even close. Removed the bamboo, then used the “death wheel” to cut out the inner wall. It was pretty amazing how perfectly it fit the conical air filter – though I did test-fit it in the store. What still has to be added is a 5″-diameter extension to pick up the duct hose. At the other end, another fabricated duct will feed air to the hose from the side air inlet next to the dry sump tank. It’s either going to be composite due to the oddball shape, or a rather curvaceous aluminum assembly.

Diffuser: after reading that excellent article, given that the bottom of the car is flat from front to back, the diffuser might actually have a chance of doing something. It’s a 24 x 48″ (609 x 1218mm) aluminum panel, with a lot of mockup work. The forward edge will be captured by the aft edge of the engine tray. Right now I’m thinking of aluminum angle below to support the strakes (yes, that’s the term), and another piece across the rear edge to prevent bending and to (very optimistically) perhaps even act as a Gurney flap. That should make it rigid, but it’s still has to be supported, either off the side panels or via tubes or cables off the inboard chassis. Mostly because of the muffler, the diffuser angle ended up being 13 degrees. Yes, I know, everyone says the maximum divergent angle should be 7 degrees, but as the article notes, diffusers run at lower speeds and with larger ground clearance can handle bigger angles. In any event, something will close off the current open area around the exhaust, probably screen just like above, though the shape needs some thought to not totally mess up the appearance.

There is a bit of concern about the nearly 2-ft extension behind the rear axle. For example, going over speed bumps, not currently a problem, could become so at certain speeds, where as the rear of the car passes over and down, the suspension compresses somewhat below ride height as the shocks compress, so the speed bump could end up kissing the bottom of the strakes. I’m trying to plan for that possibility, so that the worst that happens is a bit of aluminum gets bent, rather than it hooking on the leading edge and ripping the entire assembly off the car!

18 May 2018

The wings – not yet fabricated – will only be mounted for track events. I’m not impervious to what people think (partly because it can affect book sales) but also because I’d feel silly driving on public streets with them. While technically functional at all speeds, they’re realistically pointless at legal road speeds, so it’s sort of a lose/lose proposition. I mention this now because to a somewhat lessor extent,  the same applies to the diffuser.

The diffuser will be a 24 x 48″ (610 x 1220mm) panel with the forward edge attaching to the rear-most cross tube. Due to the muffler, it’ll have a small angle toward the front, then a larger angle behind it.

This Racecar Engineering article and Willem Toet article were both very helpful (though the latter was obviously not proof-read!). Before reading the articles, I was going to leave out the strakes (the vertical vanes always seen on diffusers, but the figures graphically show why they’re a good idea. The articles were found while doing a Google search to answer whether a flat or curved diffuser works better. While neither article answers this directly, it appears that the sudden slope change at the front edge is necessary to initiate the spiral air currents drawn in from the sides. (On a related note, most forum discussions about diffusers are very inaccurate, go figure.)

Getting back to the question about street use, I’m sort of on the fence concerning the diffuser. Like the wings, even if it works, it’s of little to no practical benefit at legal speeds. Unlike the wings though, it’s not quite as “in-your-face”, being mounted down low. Also, there’s the practical issue of where to keep it when it’s not on the car. The wing assemblies will be tall and slender, and can be stored against a wall out of the way. Not so much with a large three-dimensional diffuser assembly. As of this writing I’m leaning toward leaving it on the car and putting up with the increased boy-racer look. That said, if I can drive down a leaf-covered street and kick them up high in the air behind me, that’s so totally worth it 🙂

Before anyone says “well what about the pretentious air intake on the roof?” Unlike the wings and diffuser, cooling the intake charge is of benefit whenever the engine’s in boost, which is often, so it stays.