Power Tool Racer. Quick & on the Cheap!

by spacematters

13K1312

Intro: Power Tool Racer. Quick & on the Cheap!

The 2nd annual Seattle area Power Tool Race & Derby is just around the corner and race-tool kludgineering is in the air! Folks are building racing machines out of leaf blowers, grinders, vacuum cleaners, drills, and of course circular saws.

This instructable is meant to share just how quick and sloppy simple it can be to build a racer from a circular saw and stuff you likely have kicking around your garage. To construct such a racer you need only some old skates, scraps of wood, screws, bolts, a drill, and of course a circular saw.

The 2007 Seattle Power Tool Race & Derby is June 23rd.

Go here if you are interested in information and rules: Power Tool Race & Derby

If you enjoy this instructable and would like to join us at HazardFactory for one of our Saturday Build Days please contact me (jeremy at lowly.org)! We're happy to help you get your tools race ready!

STEP 1: Collect Materials


This can really be built from 100% scrap. In my case though I went out and bought a pair of skates and some tub/shower door rollers. In total I spent $12. If you had to buy the wood, saw, and everything you might be able to spend $50 bucks on this project.

Bill Of Materials:
  • In Line Skates (8 bucks)
  • Scraps of Plywood
  • Scraps of 2x2 or 2x4
  • Tub/Shower Roller (3 bucks)
  • Screws
  • Bolts
  • Stiff wire or a Zip Tie
  • Circular Saw

Tools:
  • Drill
  • Circular Saw (the same one!)

STEP 2: Harvest Wheel Units From Skates


I like to use the entire wheel unit from each shoe, as it simplifies assembly.

In line skates have been evolving for 2 decades... your skates will likely be different than mine. How easy/hard it is to harvest the wheel unit is something to consider if your going hunting at garage sales.

If you have skates with the wheel unit riveted to the shoe, you'll have to drill out the rivets.

  • Use your drill with small bit to make a centered divot in each of the rivet heads.
  • Switch to a larger bit to drill the heads off each of the rivets.

My wheel unit had a lower front portion so I had to use a bit of wood to as a riser to make the unit (mostly) flat.

STEP 3: Assemble Front Wheel Platform

This racer will be about 2 foot long. It will consist of a front freewheel platform and a back drive platform.

A rear mounted engine (ahem... circular saw) is one approach which puts most of the weight of the racer over the drive wheel (ahem... blade) for maximum friction.

With that goal in mind we're going to construct the front freewheel platform first.

Cut Two Cross Pieces to About 11.25 inches.
The track dimensions for the Seattle race is 12 inches from rail to rail. I like to have a little over a 1/4 inch clearance on each side to prevent the racing machine from wedging itself.

Align wheel units
This step is best done with the whole platform upside down
  • Measure front width between wheel units
  • Measure back width between wheel units
  • Adjust and repeat until wheels are in parallel

Attach wheel units
Don't add too many screws until you've tested for track fit!
  • Using a few screws attach, doing your best not to misalign the pieces.

Check fit
You can mock up a track by placing two 2x4s in parallel 1 foot apart.
  • Place in track
  • Inspect from all angles for binding
  • Roll back and forth

Add more screws
Add s'more screws so it'll keep shape!

STEP 4: Add the Rear Drive (Saw) Platform

The circular saw's metal base needs to be within a couple inches of the track to make good contact. The freewheel in line skate platform is usually a little too high. To make up the difference we'll attach the rear platform to the front platform offset with some pieces of 2x2.

Cut 2x2 offset pieces
Take your trusty circular saw and cut some pieces that will be used to attach your rear platform to your front platform. In my example I've cut two 1 foot long pieces and two 3 inch long pieces, as you can see in the picture.

Cut rear platform
I've cut a rear platform of plywood. Dimensions are about 2 foot by 6 inches. The rear platform will fit under the front platform and extend out 1 foot behind it.

Attach offset pieces to rear platform
This step is best done with the racer upside down.
  • Make sure your offset pieces are aligned well with your front platform.
  • Place your rear platform on the offset pieces
  • Attach with liberal use of screws

Attach rear platform to front platform
This step is best done with the racer right side up. It's advised that you rest it on 2x4s so that the offset pieces are snug in place where they are supposed to be.
  • Align so that rear platform extends back about 1 foot.
  • Attach with liberal use of screws.

STEP 5: Mounting the Saw

We'll attach the circular saw to the rear platform with through bolts. This is an area that I feel screws will let you down, but if that's all you've got go with 'em!

Drill holes in saw base
I haven't mentioned yet that I intend to use my saw again after the race. Totally plausible. I've selected my mount points carefully to avoid damaging the saw's metal base.
  • Mark holes, consider what's on the top side.
  • Drill holes, usually best to drill a smaller pilot hole before the final hole.

Drill holes in platform
Yo! Heres a hot TIP: most saws need to be mounted backwards to make the racer move forwards! Crazy, huh?
  • Transfer hole alignment marks to the rear platform with a sharpie.
  • Drill holes.

Mount saw
Attach securely using bolts, nuts, and washers.

STEP 6: Add Side Rollers

You don't want all the racer's energy being consumed by friction. We're going to round the front corners and add some side rollers to keep this saw in the track and off the rails.

Round Corners
  • Cut the corners off the front.

Add sider rollers
Mount your side rollers toward the front. You should have a means to adjust them once in place.

I've opted to modify my shower door rollers to bend the bracket into a bit of a right angle and attach them to the wheel units.

STEP 7: Add Cruise Control


In the Seattle Power Tool Race you'll get a foot switch to active your racer. But it's not going anywhere if you don't add some cruise control technology.

Take that stiff bit of wire or a zip tie and convince the trigger button to stay depressed!

STEP 8: Final Fit

Time to see how well the racer fits in the track. Again, you should set up two 2x4s 12 inches apart to simulate your track.

Lower Blade
Use the depth adjust on the saw to find the sweet spot where the blade makes solid contact with the track.

Bend Side Rollers
I make my final adjustments with a pair of vice grips to convince the roller wheels line up just shy of binding.
  • Fit in track
  • Roll forward
  • Adjust rollers and repeat until minimal friction occurs rolling forward.

STEP 9: Name and Decorate

If you're anything like us folks of HazardFactory, you've spent the afternoon drinking pabst and narrowly avoiding cutting off your digits. That's the perfect time to name, paint, and decorate your racer.

Pick a Great Name
Imagine sexy bombastic announcers calling out the name of your racer. Imagine a crowd rooting for you. Now pick a name that they'll be embarrassed to say aloud!

Decorate
Honestly your racer doesn't have to move an inch for you to walk home with a trophy. Fantastic imagination in the decoration department can just as easily secure a prize as fantastic engineering.

Of course you'll probably have to do better in decorating than stapling a glove to your racer... but you get the idea.

2007 Seattle Power Tool Race
June 23rd.
Races 2:30 - 7:30
Derby 7:30 - ?

I hope you've enjoyed this instructable and will be joining us for the race!

Here's a video from a photo shoot we did with popular science magazine featuring some other racers:


Thanks,
Spacematters

12 Comments

bvisser 10 years ago

Built it, raced it, got second place! Used a single sheet of plywood instead of the wood frame, and used ROLLER BALLS instead of wheels; they looked too cool at the Goodwill to pass up. Tilting the saw to the inside gave it more of a bite and balance, and made for a scary hop as it got up to speed. A crowd pleaser! Thanks for the idea!

rimar2000 15 years ago

You have given me an idea: to do a small apparatus as this to produce straight courts in any surface. I have a cutting table where I can set the hand grinder, but this would be more practical. THANKS

Rishnai 15 years ago

Hey, you used a chunk of wood as a shim! No fair! I recently used the uppers from an old set of skates, bolted to an old shelf, as a sandboard. I didn't think of using wood shims, so I made a metal bracket system out of angle iron, bolts, and blood. Heavy, but effective.

spacematters 15 years ago

I was definitely trying to limit my tool set to hand drill and the circular saw itself... sometimes it fun to work within arbitrary constrains. Normally I'm prone to over building ;)

Rishnai 15 years ago

I know that feeling, sometimes I'll just toss a paper airplane at the garage and whatever tool(s) it hits, that's the power tool of the day. Of course, there is much that can be done with a hand drill alone....

spacematters 15 years ago

I do love the hand drill... I usually suggest the hand drill for folks working with kids, the lower rotation speed reduces the danger factor. Also the chuck makes it easy to stick just about any wheel onto it.

Kaiven 15 years ago

nice! this is soo cool

smed21 16 years ago

how come there is no race in New Jersey. At least have one on the east coast. Me and my father would love to do this. If anyone knows of a race that is close to me, please reply. Thank you.

awoodcarver 16 years ago

I saw a race with power tools on TV once 2 dremels or die grinders side by won 1 race I do think seems like a fun way to get rid of that old sears dremel knock off that always needs brushes

gyromild 16 years ago

if i got right, the spinning saw blade makes contact with the track floor providing the forward drive...right? have you tried running it on the tarmac for example? did it produce lots of sparks? might ruin the the blade and the saw though.. i definitely gonna build this, and maybe try running it on the driveway, at night.. cool stuff! great instructable..