Wednesday, December 10, 2008

The G-Seat joins the setup

Several people have expressed dismay or concern about the crappy chair they saw in some of the photos here.

At last the truth can be told: the chair was a stand-in for an Ultraforce G-Seat by Pat Dotson. A couple of weeks ago iRacing released an API that allowed Pat to build a software interface between iRacing and the G-Seat - which means that I've been able to retire the chair.

Attached are some photos of the latest setup, with G-Seat complementing the pedals.

Friday, October 31, 2008

First test!

They work!

I plugged the pedals in last night and went through the calibration process. After just one small glitch I was in the Skippy and driving around Infineon. After only a few laps I was within one second of my personal best there.

Then suddenly the brakes "failed!" I went into the upper hairpin (turn 7) at Infineon and pressed the brake and nothing happened. I drove off the end of the dragstrip into the grass and then fell off the end of the iRacing "world."

A quick look under the table revealed that the crossbeam on the computer table had snagged the brake spring and prevented the pressure from the pedal from getting to the brake actuator. The table slides fore and aft, and as I drive, I tend to pull it toward me. I'd raised this crossbeam a few weeks ago, but clearly I hadn't raised it enough.

Other than that, the pedals felt pretty good, but it was clear that I needed to make some adjustments to the pedal angles and heights. For one thing, the brake pedal felt kind of soft, and I was locking up the Skippy's brakes too easily.

Since it was well after 2 AM I decided to knock off and have another go in the morning.

In the morning after some more testing I decided that I needed to raise the front of the pedal unit. I didn't like the angle that the throttle and clutch pedals were at when they were fully depressed, particularly the throttle. When I pressed it all the way down, my foot bent back at an angle and I was only pressing it with my toes and the ball of my foot.

There wasn't enough adjustment left on the pedal pushrods to get the pedals where I wanted, so I unplugged it (just a single USB connection!) and took it back to my bedroom "workshop." There was one adjusting hole in the aluminum straps, and I tried that, but it didn't raise the front enough to get the throttle at the angle I wanted.

I wound up drilling a new hole in each leg, and also doing some adjustment of the pushrods to get all of them into the same range so I could fine tune the angles once I got the height into the ball park.

I also found I had to make some adjustments to the pot actuators. The new pedal positions caused some interferance with the little plastic arms on the pots coming in contact with the large washers that serve as spring perches on the pushrods for the throttle and clutch. A little filing on one of the plastic arms and shortening the little pushrod on the other took care of the problems.

All this was minor stuff, the type of thing I expected to have to do, and fun besides. Less fun was raising the crossmember on the table, but it didn't take long to do this.

All the pedal angle tweaking required recalibration of the throttle and clutch, and while I was doing that I realized that I'd only calibrated the brake to use about 30% of the full range of the load cell. No wonder the brake pedal felt so soft! A quick recalibration got me up to 50%. I didn't want to go too high for fear of overstressing the load cell, but later Todd told me the load cell is good for up to 150% of its rated load, and that I can safely calibrate for 90% of its range.

Anyway, soon I was back in the cockpit of the Skippy. Now the throttle pedal angle was good, but the angle of the clutch and brake were too high. I was snagging my foot on the bottom of the clutch pedal when I tried to use it.

A few minutes with a couple of 7/16" wrenches and I'd cut back on the angle, and raised the brake and clutch pedals relative to their shafts, while lowering the throttle pedal relative to its shaft. All that adjustability we (and Todd) had designed in was paying off!

Now the angles and heights were just about perfect, but the throttle and brake were too far to the right. A few minutes with an allen wrench and I'd slid all the pedals to the left so their lateral positions were pretty much optimal too. Bravo to Todd for his design, and to Amos for his careful machining. It was very satisfying to be able to make all these adjustments so smoothly and easily.

Back in the car. This thing rocks! Within a handful of laps I was under my previous personal best. A few more laps and I'd lowered it by half a tenth, with several more laps within a tenth of the best.

This may not seem like much of an improvement, but I have not been driving much in recent weeks, so I'm rusty. Plus, there are a lot of variables. I'm using the new iRacing build, some different FF and steering linearity settings, and a different setup for the Skippy.

What is clearly different is how much more consistent I was. It's very rare that I am this consistently close to my personal best.

I still have more fine tuning to do, and I also think it will take me a little time to fully adapt to the pedals. But already I think they are better than my modified G25 pedals, which in turn were better than the stock G25 pedals.

So far I feel very gratified with the results of the project, and I'm looking foward to putting some more miles on the pedals. I'll report back soon.

Thank you Amos! I loved working with you on this project, and I really appreciate all the hard work you put into it. I'm really looking forward to building your set.

And thank you Todd! Thanks for all your help, and thanks for creating such a terrific concept and such a well executed design.

Thursday, October 30, 2008


At last the pedals are wired! I've had them at home for a couple of weeks now, but various distractions have delayed their completion.

I also completed some other details once I brought the pedal unit home. I added some glides to the "feet" to protect my landlady's shiny new (but very soft) Chinese oak floor, and built a heel board and attached it to the feet below the pedals. I also spent some time adjusting the travel of the pedals by shortening the plastic tubing that fits over the threaded pushrods.

Finally, this evening, after a lot of snipping and soldering and shrinking of heat tubing, the wiring is done.

I used a project box from Radio Shack to enclose the Leo Bodnar load cell controller. It's way bigger than necessary, but the next smaller size available from Radio Shack was too small. Anyway, with this one there was plenty of room for a loop of extra wire inside. And despite the extra room inside this box it was still pretty tricky to get the load cell wires into their tiny little sockets on the controller board.

One thing I'd do differently next time is to get some 22 or 24 gauge wire instead of using the 20 gauge I had on hand. I tried to get some from Radio Shack but they don't have stranded wire that small, so I figured I'd make do with the 20 gauge.

But it's harder to solder to this thicker wire without getting the little posts too hot and melting something, plus the stiffer wire is more annoying to deal with, especially within the tiny confines of that little project box. I'm sure Digikey or YouDoIt or someplace like that has smaller stranded wire.

I left some slack in the wires so I will have room to move the pedals side to side a little as necessary to get perfect adjustment of the brake and throttle for heel and toeing, and to get the clutch in a comfortable position relative to the other two pedals.

Note that a standard USB cable plugs into the Bodnar load cell controller board through an opening in the bottom of the project box.

The next steps are to slide the G25 pedals out of the way, slip the new pedal assembly into place under my desk, hook it up to the computer, install Todd's software, and calibrate the pedals. And then DRIVE!

Don't you feel flattered that I took time out to post these photos for you first? ;)

(BTW, I'm sure these pedals will lop whole seconds off my lap times and make me as fast as Greger Huttu. Not!)

Tuesday, October 21, 2008

Trial Fitting

Finally the pedal unit is "home"! Here are some shots of its trial fitting under the desk in my racing dormer.

I had to modify the table that holds the monitor, wheel, shifter, mouse, and keyboard. The horizontal crosspiece at the rear of the legs that gave it a modicum of horizontal stability was too low to clear the tops of the pedal mechanisms, so I had to move it up about two inches.

Now the table's legs are even more wobbly, so my next project, once the pedals are done, is going to be to add some boards to the outside of the legs and some 1x1's in between to create a box section, which should be much stiffer.

Another small thing I did was to add plastic glides to the bottoms of the "feet", front and rear, and also projecting out from the rear surface of the feet, resting against the baseboard to prevent the feet from damaging the nice quarter-round molding at the intersection of the floor boards and the baseboard.

Anyway, this trial fitting shows that the pedals do indeed fit into their planned location, and they seem to look quite happy there!

What's left? The wiring, and fine tuning the pedal ranges and angles. Then I can try them!

Also I need to make a nice heel board out of poplar, and if I find I'm happy with the pedal heights and angles, I'll go back out to Amos' and use his table saw to make some poplar legs and feet to replace the temporary pine pieces.

PS. Please ignore the mess on the floor behind the pedals. There's a surge suppressor and a UPS and a bunch of cables. That will all be tidied up once the pedal installation is finalized. I promise!

Overview Shots & Pedal Pad Adjustment

Here are some wide-angle overview shots of the completed assembly, sitting on a work table in Nate and Amos' garage. Please ignore the ugly scrap wood heel board for now.

Note that although the throttle pedal arm is at the same angle as the brake and clutch arms, its pedal pad is not only longer but mounted closer to the arm than the other pedals. This is to facilitate heel and toeing. The throttle pedal pad has only a couple of washers between it and the pedal arm, while the other pedal pads are mounted considerably further away from their arms.

The clutch and brake pedal pads are adjustable in terms of height from their pedal arms, similar to those on Todd's production pedals. Instead of using plastic spacers as specified in Todd's DIY plans, I used nuts to lock the flat head bolts to the pads, and then used a pair of nuts on each side of the pedal arm to clamp the bolt to the arm.

This allows me to make some adjustment; all I have to do is loosen the nuts, twirl them up or down for more or less distance to the arm, and then tighten them. If I need more, I can simply substitute longer flat head bolts.

Oh yes. Just in case you're worried about me overtightening the nuts and squashing the pedal arms, which are made of 3/4" square aluminum tubing, don't be. We used tubing with 1/8" wall thickness for these, instead of the 1/16" specified in Todd's plans. They are plenty strong!

The pedals are now ready to go home to my apartment with me. Amos was sad that he won't be working on the pedals with me any more. I was too, very much so. We had such a great time working on them together! But we are looking forward to building a set for him, as soon as he has time.

The next step will be a trial fitting at my apartment, to see if the angle and position of the pedals feels right when rear of the feet (the "heels"?) are up against the wall in the dormer where my racing computer lives.

Leg Attachment Details

While Amos was madly drilling and reaming, I cut and drilled aluminum straps which would be used to attach the aluminum tees to the legs, which we'd made of pine. (Amos did some of the work on these straps too.)

I plan to replace the pine with poplar, but we decided to use the pine for the initial build, in case we wanted to change something, because pine is a little cheaper than poplar so it would be less painful to throw it out if the original parts didn't work.

It took some fiddling and trial and error to find the lengths we wanted for the aluminum straps to get the pedal heights and angles just right.

I wanted to make the pedal unit low enough that I would be resting my heels on the floor, but Amos voted for using a heel platform across the tops of the "feet", the 1x2 strips of pine that bolt to the bottoms of the legs. He felt this would raise the overall unit, giving a more natural angle when you're sitting in a chair, and requiring less tilt on the pedal unit to get the pedals at just the right angle.

We don't have the height adjustment relative to the floor that Todd's production design does, but we do have some angle adjustment, both at the leg attach brackets and by changing the length of the pedal pushrods.

Legs On! The Project Comes Together

At right, Amos has finished his precision drilling and reaming and is beginning to reassemble the parts of the brake pedal assembly onto the brake pedal platform.

Note that in this photo, the pedal platform, bracket, and rod assembly is sitting on the wooden mockup I made several weeks ago to use for trial fitting and testing.

This mockup has proven to be quite useful, both for initial testing of pedal heights and angles, and also as a work platform on which to sit the pedal assemblies while we were working on them.

In the next photo and the ones below, the metal assembly is bolted to new wooden legs in the configuration which we expect to be final, although these legs are temporary ones made of pine.

We also reassembled the throttle and clutch pedal assemblies and pushrods and springs onto their respective platforms.

While Amos was doing all his precision drilling and reaming, I marked and cut the brackets to which the legs would be attached.

We came up with a tee design that would have approximately the same structural function as the steel weldments used in Todd's production design, but our design used rectangular aluminum tubing, bolted together.

I marked the holes in these tee brackets and drilled some of them, but Amos took over for the half inch horizontal holes that would accept the steel rods, including them in his process for drilling the precision holes in the pedal platforms.

Note that - unlike in the first photo, above - the bottom (vertical) part of the tee brackets have been bolted to the horizontal parts by long quarter inch bolts running vertically through both parts.

Amos also drilled the holes for the bolts that hold the tees together. Amazingly, all of these 1/4" holes lined up so well that the bolts just dropped through without any reaming at all. Amos has become brilliantly skilled at doing precision work - with a drill press that has a bent chuck!

One thing you can't see in these photos is that Amos made small spacers out of some scrap aluminum (actually an old shifter kart tie rod!) to fit inside the upper part of the tee (the crossbar) around the 1/4" bolts, so that tightening down on the bolts won't squash the aluminum crossbar. It's made of 1/8" wall tubing, so it's pretty strong, but these spacers allowed us to tighten the bolts quite firmly, which makes the whole assembly more rigid.

One last thing: note the round steel collars next to the platforms and tee brackets. These have set screws in them and will allow us to lock the pedals in place once we've settled on their lateral positions. This idea comes straight from Todd's production pedals, and gives this design its terrific lateral adjustability.

Keep in mind that the legs and feet are pine and the heel board is a piece of pine scrap, long ago painted what looks like might have been white. We plan to eventually replace these wooden parts with poplar, which will look much nicer and also be stronger and stiffer - and less smelly.

Brackets and Rods: Precise Machining Required

On October 12 Amos and I got together one more time to work on the pedal project. By the end of the day the pedals would be assembled, standing on their own two feet, ready for wiring.

The first step, though, was dismantling all three pedal units. Amos stripped them right down to the bare minimum, removing all the parts that were bolted on, and some of the parts that were riveted on as well.

He needed to do this in order to drill four very precise holes in each pedal platform. These holes needed to line up with each other, because half-inch steel rods would slide through them to hold the entire assembly together. If any of the holes didn't line up, the pieces wouldn't go together. And if there was any slop in the holes, the pedal platforms would move around when the pedals were pressed.

In addition to the three pedal platforms, there were two brackets, one on which end, to which the legs of the pedal unit would be attached. These, too, had to slide onto the half-inch steel rods.

So Amos had a lot of very precise drilling and hand reaming to do. Since the drill press on hand wasn't really accurate to get these holes dead on, he came up with the plan of carefully slotting the rear holes in each platform and bracket by hand, just enough to allow the two steel rods to go through.

Here are some photos of the completed assembly. He did it! There's no discernable play, yet the pedal platforms and brackets slide freely on the steel rods. Awesome work.

Monday, September 22, 2008

Three Fine Assemblies

With all three assemblies completed, we of course had to line them up on the mockup stand to see how they looked all in a row like soldiers.

Be sure to click on the images to see the larger 800x600 images. These show a lot more detail.

Don't these things look terrific?

The next steps will involve dismantling the pedal assemblies so we can drill half inch holes in the aluminum channel sections for the 1/2" galvanized steel rods that will support the pedal platforms.

We waited to drill these holes until we had completed the assemblies because we wanted to make sure that wherever we ran the steel rods through, they wouldn't interfere with bolt heads or rivets or anything else attached to the sides or undersides of the channel section pedal platforms.

Now that we know where everything has ended up, we can position the holes for the rods with confidence.

After that, all that will remain will be construction of the actual pedal base and installation of the load cell controller and wiring.

By the way, the day after we did this work on the pedal project, Amos totally destroyed the absolute lap record at Rocky Ridge in his stock-engined shifter kart. He won the heat race going away and was charging in the feature when a hub broke and put him out, leaving the way clear for his dad to take his own first shifter kart feature win. With one race day to go, Amos has a healthy lead in the Vermont Shifter Kart Stock 80 championship.

Way to go, Amos!

Pot Mounts and Actuators

No, this has nothing to do with either cooking or weed.

The throttle and clutch pedals work by operating a potentiometer, which is a variable resistor. Each of these will be connected by a couple of wires to the Leo Bodnar load cell controller, which has circuitry to deal with switches and pots as well as the load cell.

The little bracket that mounts the pot to the top of the pedal platform is made from a 3/4" long piece of 1" angle aluminum. The pot is the black plastic box with the little solder tabs sticking out to the left.

The pot actuator arm is made from a piece of gray square plastic rod we ordered from McMaster. The minimum was three feet and we only need about six inches to do both pedals on both my and Amos' (yet to be built) pedal sets, so we have a lot left over! Fortunately this stuff cost about a dollar.

It's also very easy to work. Which is lucky because I drilled the hole for the pot shaft a little bit oversize in the first one I made, so I had to make two more. This took about ten minutes each.

Once we'd cut some 6-32 threaded rod for the pot pushrods we were able to assemble them together with the little R/C aircraft rod ends and 4-40 screws, nuts, and washers, and figure out exactly where we wanted to mount the pot mounting brackets to make sure we got free motion throughout the range of travel of the pedals.

We were also hoping for linearity of operation of the pot, but given the geometry that's pretty much impossible. However, we think that the nonlinearity will be advantageous, with slower ratio at the beginning of the pedal travel and higher ratio at the end of travel.

I think this is wicked cool!

Throttle and Clutch Final Assemblies

While Amos was doing all his work on the brake pedal and actuator assembly, I fabricated the bracket that the front end of the throttle spring would be pressing against.

I also drilled out the rivets in the corresponding bracket for the clutch spring and cut a quarter of an inch off the bottom of the bracket to make it match the length of the new throttle spring bracket, and then riveted the little angle bracket back on.

I did this to lower the height of the front end of the pedal pushrods so the pushrods would be more nearly level. I thought this would look better, and also it fixed it so the up-stop (the large steel and rubber washers at the front of the assembly) were resting nearly flat against the front side of the spring end bracket.

At this point I was ready to assemble the spring end brackets and their diagonal braces to the clutch and throttle platforms. After a bunch of drilling and riveting, the job was done and the throttle and clutch pedal assemblies were complete.

Brake Pedal Final Assembly

More progress! In fact, at this point it feels like we're nearly done.

On Saturday we spent a long day completing and assembling each of the three pedal assemblies.

This day felt different from the previous days, however. At this point we are so far along that there was very little time spent dithering and making decisions, then reconsidering and deciding agaian, as we'd been doing most of the previous days of this project.

Instead, we found that things were falling into place. Both of us simply kept working: measuring, drilling, cutting, filing, riveting, and bolting together. It was a rewarding day!

Amos spent most of the day working on the most complex assembly, the brake. He drilled the pivot holes in the u-bracket that mounts the load cell actuator and then spent some time tinkering with the alignment to try to get the actuator perfectly square with the tongue he'd fabricated earlier and mounted on the load cell.

He also determined where he wanted the u-bracket to sit on the pedal platform, and drilled the holes for that.

Along the way he decided to put a shim under the rear end of the load cell, and then during the alignment process he also made a shim to go between the u-bracket and the pedal platform.

It also took some tweaking to get the spring situated so it didn't flex sideways and hang up on the nut on the threaded pushrod inside it as the pedal is actuated.

By late afternoon the complicated brake pedal assembly - the part of the project that had required the most design work and the largest amount of precision fabrication - was complete.

Didn't Amos do a fantastic job on this?

Wednesday, September 10, 2008

Hot Shoes

And now, at last, we get to see the pedals in action (sort of).

Here are some shots of the clutch and brake pedal assemblies sitting on top of the mockup floor stand. Don't they look cool?

We haven't got a throttle assembly yet. I know I said we did in an earlier post, but actually that was the clutch assembly masquerading as the throttle assembly so we could gauge the relationship of the throttle pedal to the floor.

In reality, the throttle and clutch assemblies will be identical except that the throttle will have a longer pedal pad to facilitate heel and toeing.

But in our case, the first pedal shaft and platform assembly Amos made has a little bit of play in the pivot between the two, because Amos was learning how to deal with a slightly bent chuck in his dad's drill press. This makes the drill bit wobble and makes it difficult to produce holes that are precisely the right size and in precisely the right place.

By the time he made the second and third pedal shafts, Amos had mastered a technique that allowed him to drill extremely precise holes despite the defective chuck. Since a small amount of side to side wobble is less critical in the clutch than it will be in the throttle and brake (again, for heeling and toeing we want them to be stable laterally) we've decided to use the first assembly for the clutch and use the more precise later assemblies - which have no play at all - for throttle and brake.

Anyway, in these shots you can see how the assemblies will look when finally mounted on the finished pedal stand (which we haven't started building yet).

Amos kindly contributed his shoes so that we could demonstrate the operation of the pedals. The shoes are having a rather hard time heeling and toeing, though, because of the absence of the missing throttle pedal.