Archive for the ‘Pedal car’ Category

24
Mar

Reset

   Posted by: Mark

Looking back, it’s been three and a half years since I’ve posted anything out here! Two things:

First, the pedal car is still not done. I haven’t touched it since before the last post out here. It’s a travesty, because it has the potential to be so incredibly beautiful, and fun for the kids! Perhaps this summer…

Second, I’ll be documenting a new venture here soon. Lots to learn, lots of hard work left to do, but I think this one will be fun to follow, and I know it will be fun to post. Stay tuned!

15
Jun

Building an MG-TC pedal car: Part 4a

   Posted by: Mark

Refer to the Introduction for links to all of the posts in this project. This is a continuation of Step 4.

About a week ago I was able to get both the steering and drive systems complete, which had been a hug hurdle for me. After some brainstorming with Dad and some poking around at the Orange Box, I found all I needed.

The plans had called for a galvanized pipe for the steering rod, flattened and bent up at the tie-rod end and fixed with a pipe flange at the other for connection to the steering wheel. I had a version of this completed, but was never satisfied with the roughness of the steering. Not only was it difficult to steer, but it wasn’t particularly reliable. So I ended up using a 3/8″ diameter piece of steel for the steering rod. At the bottom end near the tie rods, I bent it up, ground the sides a bit to make some flat surfaces, and used U-bolts to fasten a 1 1/2″ x 4″ section of flat steel. The tie rods bolt to this flat steel, and there is amazingly little play in the whole thing.

I had ordered tie rods with the ball joints, but the shortest they had were 11″, and I needed something around 8″ long. I used 5/16″x24 threaded rod (or all-thread), which is great because I have enough play to allow adjustment of each wheel separately.

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It’s not the prettiest steering ever created, but it works very well. The steering rod comes through a piece of scrap that I screwed to the front of the body because the original steering column hole was about an inch in diameter to fit the pipe called out in the plans. Once the grill is in place it should look much more clean.

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You can see the flattened sides of the steering rod. The U-bolts I had bought were pretty small, so I had to grind the sides of the rod to get them to fit. There’s no chance they can slip or move — they’re on VERY tightly.

And here’s a poor-quality video of the steering in action. The angle on the tie rods is a lot greater than I would have wanted, but at this point I’m not willing to redo it all. The kids could care less, and I just want to get it painted!

For the drive system, I had two problems: I couldn’t figure a way to affix the single drive wheel to the 3/8″ steel axle rod, and I didn’t know how to attach the drive rods from the pedals to the crank. Although I’m not yet convinced the lifespan of this solution is all that long, I ended up drilling a hole through the drive wheel hub and the axle, and inserted an “R” clip through the holes. My concerns with this are that the hole I drilled is pretty large relative to the small 3/8″ axle, and the hub isn’t really designed to handle the torque that can be applied by an excited child. We’ll see how long it lasts. So far it doesn’t show any wear, so that’s promising.

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Getting a picture of this was harder than I expected, and the sun was fading fast. In the picture above you can see the loop on the “R” clip. I still need to trim the axle, but I’ll probably wait for final, post-paint assembly before I do that. You can also see the colored label on the tire in this picture, which is another thing to fix in final assembly (all the other wheels have the blackwall point out, with the tire graphic hidden; yes, I have issues).

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It’s really tough to make out the “R” clip here, but you can see the top loop of the clip on the right.

For the drive crank, I drilled holes in the drive rods just large enough to be able to slip the axle through them, and threaded them on with a washer and small pipe-band-clamp on each side. The washers and pipe clamps keep the drive rods in the same spot on the crank, and insure that the drive rods don’t slip up the sides of the crank. It’s another case of “not pretty, but quite functional.”

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And here’s another questionable-quality video, this one showing the drive crank and pedals in action. Again, not all that smooth because I was trying to keep the camera steady with one hand. Also, both this video and the above steering video might give the impression that there’s a ton of friction in the two systems. They’re certainly not finely-tuned, but they really are pretty free and smooth.

Refer to the Introduction for links to all of the posts in this project.

The past two days have been VERY productive days with the pedal car! Not since the body went together have I accomplished this much in such a short amount of time. I finally worked a very usable solution for the steering (at BOTH ends of the steering rod!), and finished that last night. Then today I was able to devote about four hours of uninterrupted time to redoing the drive mechanism, and that’s working better than I could have imagined (thank you, Dad, for your ideas and help, and Tami for letting me do it!). Once the kids drove that around for a little while, I realized I just had to get the fenders mounted. And man, what a difference it’s made having those things on the car!

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I’ll update Part 4 with details and pictures as soon as a I have a chance to get some decent shots of what I’ve done. Until then, perhaps these videos will hold you over! The kids ran it for about three hours today, and the worst I had to do was add a seat support (for those with longer legs) and tighten a few nuts that worked loose.

One of the huge helps in all of this has been the comments and emails I’ve received on some of the other posts in this series. Seeing interest in this project is really pushing me to get it done, so thanks to all of you who have stopped by!

2
Mar

Building an MG-TC pedal car: Part 4

   Posted by: Mark Tags: ,

Refer to the Introduction for links to all of the posts in this project.

This post is focused on the steering and drive components of the pedal car. These two areas have been the source of 95% of the problems, stalls, and headache for me. Admittedly, the primary reason for this trouble is my decision to use bicycle wheels instead of the plan’s plywood wheels. But no matter what I do, I can’t convince myself to eliminate the wire wheels. So I’m stuck with trying to come up with efficient ways to make it all work.

One of the commenters on the Introduction post indicated that he had built one of these years ago and used go-kart parts for the steering, which resulted in me searching for some parts I could use. I did find some web sites with decent prices, and am now waiting for a couple of sets of ball joints and tie rods, $20 with shipping. I may also break down and buy a cheap MIG welder for a few things (I’ve been wanting one anyway), but haven’t decided on that yet.

It seems I am now regularly finding ways to improve on this whole project. Bearings are so cheap that using pipe fittings and brass bushings seems silly. Kingpin assemblies are relatively inexpensive and much more clean than what the plans call for (though I am still a bit impressed with that whole assembly, made with pipe fittings). Chain drive doesn’t look all that difficult, especially with the decision to use bicycle wheels anyway, and the possibility of having a welder (though this raises some issues such as braking and coasting, but I’m planning to put together a summary at the end of all of this to address some of these things).

This post will be updated after the tie-rods and joints arrive.

*** UPDATE 3/5/09 ***

The ball joints are here, but only one tie-rod made it. They apparently only had one in stock, but the other should be coming (soon?). I expect to get a bit done this weekend, and look forward to posting some pictures!

*** UPDATE 6/8/09 ***

Hot dog! All the steering came together tonight, praise the Lord! I have a few bolts to replace since I got the wrong size, but I figured out how to make a pittman arm without any welding! Man, I’m so excited to get over this hurdle. I’ll post pics as soon as  I have the correct bolts (tomorrow?). I still need to attach the steering wheel, but that’s the easy part.

16
Sep

Building an MG-TC pedal car: Part 3

   Posted by: Mark Tags: ,

In Part 1, I showed pictures of the basic frame of the car, as well as the mounting of the rear wheels. In Part 2, I showed the mounting of the front wheels and the mounting of a frame reinforcement plate at the rear of the frame to provide stability. In Part 3, I’m going to show how the fenders and body were assembled. I think this was the most exciting part for me, because it resulted in the pieces that provide the defining look of the car: huge roll fenders! These are what make the kids call this their “Chitty Chitty Bang Bang” car.

Before I go into that, though, I want to mention again that so far, this series of posts has been a bit of catch-up, since the work to this point has been complete for some time. But I did make a significant new accomplishment this past weekend by finally affixing a rear wheel to the drive axle! I was able to temporarily attach the drive rods to the pedals, and the kids were even able to pedal around a bit! I can’t tell you how exciting that was. I’ll get more into this in the next post, I think, but I just had to at least mention it, since this was one of the primary stalling points in the project for me years ago.

And as I look at the sub-par appearance of some of this thing, I feel it necessary to re-iterate that the foundational premise of the original plans I am following is that “anyone can build this.” So of necessity, a lot of the construction is incredibly simplistic. I have already discovered so many things that could be done better, more cleanly, even more simply. I’ve always struggled with completing projects when they don’t look perfect, or fail to meet my expectations. But this time I’m pushing through to get it done, even though so much is imperfect. Anyway, that’s my disclaimer.

As I mentioned in the introduction, I have had the project completed up to this point. Because of that, I wasn’t able to completely disassemble the body and fenders, so the pictures go from “templates” to “finished body components” without any in-between pictures.

When I started on this part of the project, I really expected to whip the whole thing together, learn a lot, and then build another one. Because of that, I created templates out of a 1/8″ hardboard material so that I could create multiple pieces all exactly the same. I have templates for the front and rear fenders, front grill, body sides (this was out of 1/4″ plywood instead of hardboard), steering wheel, and windshield mount, all pictured here:

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Using these templates, I traced outlines on 1/2″ plywood for most parts, except for the tops of the fenders, which are 1/4″ plywood because the thinner ply allows the shaping to the contours of the fender sides. Bending these along the fender contour was as simple as placing screws ever inch or two to slowly form the tops to the sides. I used Gorilla Glue as I went along, since my plan was to only use the screws in lieu of clamps to hold things together while it dried. Once the glue did dry, I took the screws out to allow for shaping the edges. Here are a couple of pictures I found from initial construction of the rear fenders before I took the temporary screws out:

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To shape the edges, I cut out a little 1/4 round concave shape in cardboard to check my progress, and used a heavy rasp to take away wood. The cardboard cutout allowed me to rasp the wood for a bit, check the contour, and then work off a bit more where necessary. Once the rough contour was completed with the rasp, I took a 40 or 60 grit sandpaper on a longer block to even things out and provide some smooth, even lines. The results are shown here for the front and rear fenders:

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The body is comprised of two full-length sides, the hood/top , a solid-wood front, the seat and rear, and a crossbar for hanging the pedals. I found a couple of older shots of the body in one of the earlier stages of construction:

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The hood is 1/2″ plywood, which made it necessary to put some relief cuts on the bottom side. Near the back of the hood (the dashboard end) there is a series of cuts half-through the thickness for about half the length of the hood, allowing the rounded shaping. At the front of the hood (the radiator end), there is a single cut on the underside right in the middle to provide the sharp peak. The result is a really cool looking transition from a rounded shape near the back to a pointed shape at the front. Using the same process as was used to round the fenders (rasp, cardboard contour template, coarse sandpaper), I rounded the transition from the hood to the sides. The result looks like this:

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The front of this will be covered with a single piece of plywood cut and painted to look like a radiator, which will clean up the appearance a bit and cover the extra steering holes.

There is still a lot of filling necessary before I can paint, and I’m not sure yet the best way to seal things, but I have a few ideas. (Suggestions for sealing and sanding plywood for a very smooth, non-grained finish would be much appreciated!) I’ll be able to provide some progress photos once I start on that process.

In the next post in the series I expect to address the finalization of the drive axle and the steering controls, though I have a little more work to do before I can share that.

Here are a couple of teaser shots of the body mounted on the frame, sans fenders:

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The full Flickr set contains all of the pictures included in these posts, plus even more for additional detail. They also have descriptions on them that explain a bit more than I have been addressing in the series posts.

9
Sep

Building an MG-TC pedal car: Part 2

   Posted by: Mark Tags:

In Part 1, I showed pictures of the basic frame of the car, as well as the mounting of the rear wheels. In Part 2, I will explain and show the mounting of the front wheels.

I should start off by saying that this is not a go-cart, is not meant for high speed or heavy drivers, and is supposed to be basic enough to not require welding. And I’m learning enough with this go-around that I would likely not do a lot of this the same way a second time.

That said, the front wheel mounting mechanism outlined in the plans is really pretty neat and creative. A kingpin assembly is built up from a galvanized pipe T, with male reducers fitting into each end of the “top” of the T, and a three-inch length of pipe screwed into the “vertical” part of the T to allow for the tie-rod. The wheels are mounted by drilling through the T pieces perpendicular to the three-inch tie-rod post (study the pictures and it should make sense):

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The T’s are then mounted “sideways,” with the reducers attached through the two 3/4″ thick wood cross-members to galvanized pipe caps. The wheels spin freely on their axles using the stock bearings (and the stock axles, which happened to be just long enough), and rotate left and right on the reducer threads for a very simple but effective steering mount.

I mentioned previously that some of the supplies available today in the big-box hardware stores are not of the same quality as the supplies available 20+ years ago when these plans were written. One example of this is the tie-rod that is supposed to be used to connect the two front wheels together (not shown in any pictures yet). The plans call for a threaded rod that mounts a steering rod receiver and is bent on both ends to fit into the steering arms on the kingpins. Unfortunately threaded rods today are incredibly cheap metal, and will invariably break when bent. But in the end I discovered that this is a very limited tie-rod design anyway, and allows for absolutely no adjustments after mounting. I surely don’t expect to be able to fully align the front wheels, but there is an advantage to being able to at least rough-tune the alignment.

After stopping at Coventry Cycle Works in Portland last weekend, I came away with some really great ideas for a steering mechanism (I was thoroughly impressed with this place, and am grateful for the assistance they provided!). I learned about a connection called a heim joint that is essentially a ball-and-socket assembly that allows more freedom of motion than a straight bolt and tie-rod might. If I build another of these cars, one of the changes will be in the steering assembly, and I would really like to mount the wheels differently and make use of a pair of heim joints. This would likely coincide with a much lighter kingpin assembly, too, since the galvanized pipe, although creative and cheap, is bulky, heavy, and a “brute force” solution instead of a “finesse” solution.

The cross members are spaced to allow them to slide over the front of the frame, and the top cross member is screwed to the frame sides. The notches in the frame just in front of the front wheel assembly are for the tie-rod, and will be covered with a strip of aluminum to provide a more finished look in the completed vehicle.

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At this point, the frame is complete, the rear free-wheel is mounted, the drive axle is bent and mounted, and the front wheels are mounted. I still need to finish the mounting of the rear drive wheel, but will wait to address that in Part 4 since I’m not really sure how to do it yet.

The next post, Part 3, will cover the rough building of the fenders and body, and will get the series of posts caught up to where I actually am right now with the project.

6
Sep

Building an MG-TC pedal car: Part 1

   Posted by: Mark Tags:

As mentioned in the Introduction, I purchased the plans for this pedal car project from Stevenson Projects a few years ago. These plans are at least 20 or 25 years old, and are not professional CAD drawings, but the good news is that they don’t need to be to be effective. They are detailed and clear where necessary. They claim that there are no special skills like welding necessary to build the car, and that may be true, but I deviated enough from the plans to get stumped in a few places.

As is my habit with things like this, I read the plans over completely at least three or four times after receiving them and before making any supply purchases. I knew from the start that I would be changing them in a couple of key areas, and wanted to be sure I understood the original intent of every step.

The supply list includes a number of items that I know now were constructed of much better raw materials when the plans were written than they are now, such as angle brackets and galvanized pipe fittings. But with some creative thinking and plenty of browsing at local hardware stores, I think I’ve been able to do okay with substitutes and a bit of trial and error.

The fundamental design of the car is based on the old, common pedal car drive mechanism: drive rods and a crank axle. The pedals move back and forth to crank the drive axle instead of in an orbit as standard bicycle pedals move. These pedals are tied via drive rods to a specially-bent rear crank axle that drives one rear wheel, with the second rear wheel spinning freely (without a differential, only one rear wheel can be the drive wheel or things will lock up when you attempt to turn). The frame is made of 1″ fir and 1/2″ plywood, and the body and fenders are almost exclusively 1/2″ and 1/4″ plywood.

Each front wheel is mounted on an ingenious assembly of cast iron pipe fittings that lets them rotate easily on the threads. Short arms extend from each assembly to provide an anchor point for the tie-rod.

The primary deviation I made from the plans was to choose real spoked bicycle wheels instead of the solid wood wheels detailed in the plans. Unfortunately, this seemingly-simple change was tied to the two most complex pieces of the project: the steering and the drive mechanism. By choosing wire-spoked bicycle wheels, I made the general wheel mounting instructions from the plans completely useless, and forfeited any obvious method for connecting the drive axle to a rear wheel. This is what derailed the project after my intial progress, and only after talking with some very knowledgeable folks have I been able to get back on track.

I started this project years ago, and it has sat, unfinished, in the garage. As a result, the freshly-cut look of the wood has been dulled with dust and piles of typical garage junk. But I have disassembled as much as I could, taken pictures to show progress, and reassembled things. The following subset of pictures shows some of the frame and rear wheel mounting progress. The full set with descriptions on each image is available on Flickr: MG-TC Pedal Car.

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My next post in the series will show the front wheel assembly and mounting, and then on to the body and fenders.

A while ago I purchased plans for a MG-TC pedal car from Stevenson Projects (called the Pedal-TC). They apparently no longer sell these specific plans, but they do sell plans for two other pedal cars here. I’m awaiting a response on availability of the original plans, and will post info as soon as I receive a reply from them.

I am finally finishing this project. I started a few years ago, and let myself become distracted. Since the kids are not getting any younger and the unfinished car nags at me every time I look in our garage, I decided to finish this big “to-do.” And I know that once it’s complete, I will want to build another to make use of all that I’ve learned with this one!

I currently have most of the basic body complete, but am going to disassemble enough of it to show detailed pictures of various construction steps. Much of the construction is pretty basic, but as might be expected, the most difficult aspect of the car so far has been the steering and drive mechanisms. And although there are lots of resources out there on the web for building Human Powered Vehicles (HPVs), all are focused on the construction and use of a practical commuter or race vehicle, not a toy or “for fun” project. I have yet to find any resources for anything at all that is directly pedal/drive-rod powered but not chain-driven. This is pushing me toward making a chain-driven vehicle if I do build another of these fun toys, but for this first iteration the direct-drive was supposed to be more simple.

I’m going to set up a Flickr set for all of the pictures I take of this project. My hope is that this may become a bit of a resource for anyone out there attempting to build this vehicle or a similar one. I thought it might be fun to journal the construction, too, since there things I am learning along the way that will be of benefit later if only they can be remembered.

Stay tuned for the first construction pictures in the next post!

**** UPDATE: 3/2/2009 ****

I received an email from Pete at StevProj. It sounds like they are still hoping to update these plans and make them available for sale, but the large format of the plans and the lower volume might be raising the cost more than they want. No indication as to a timeline.

**** UPDATE: 5/18/2009 ****

I received another email from Pete Stevenson at StevProj and forgot to update this post with his info. He related that they now have the plans available for the MG-TC! I haven’t seen them on the StevProj site yet, but you can email Pete at the general StevProj address: mail@stevproj.com