Frederic's Backbone Kart

[jr dragster T]

i forgot to tighten the bolts on my kart seat before. we all make mistakes!

Better then forgetting to torque the rod bolts that's for sure!

 

[frederic]

You should add a note infront of the machine that says MAKE SURE ALL JAWS ARE TIGHT i forget stupid things like this all the time on stuff. i forgot to tighten the bolts on my kart seat before. we all make mistakes!

This was the first time this ever happened to me. The one lathe mistake I make often is I forget to remove the chuck key from the chuck before I turn it on. Since I run my machine in reverse most of the time so the cutting is on my side of the material, that means the key comes right at my head.

I even welded up a simple key holder to the metal cabinet underneath the machine and I still cannot seem to remove the key and put it in the holder consistently.

I do not have this mental block with drill chucks, only the lathe chuck, and only the 4-jaw. When I have the auto-center 3-jaw on there I for whatever reason always remember to remove the key and put it in the holder.

::headscratch::

Many moons ago I built a mid-engined sports car from scratch. On one of the many Sunday's I slaved on this thing, I was mocking up the front suspension and the usual place I buy graded hardware for such things was closed as is the norm on weekends.

So, I went to Home Depot and bought ungraded bolts for the mockup. Nothing wrong with that however I found out the hard way (two years later) that I had never swapped them out with graded hardware.

Seemingly ungraded 5/8" bolts are good to about 95 mph. Driver's side upper a-arm broke off it's mounts, the wheel kicked back and hit the tub, flipped the tub (and me) over a few times while the thing spun around as well.

Thank God for racing suits, helmets, 5pt harnesses, and a plethora of friends watching you make a fool of yourself, said friends mostly being fire/EMT types.

I got off lucky... cracked helmet and broken pinky. The car, well, let's just say it was a waste of about five years of my life.

 

[frederic]

After a while I imagine these pictures start to look the same. I know the work seems the same day to day but maybe that's due to a much lower level of caffiene as of late.

Pic 1: Machining the axle stub for the other side, rear.

Pic 2: I've been machining the rear axle stubs, spindles and wheel flanges off a diagram, stopping every so often to measure things with a digital caliper. As they say, proof is in the pudding and here you can see the tire on the wheel, and the wheel bolted to the wheel flange. You can "barely" see that the machined center of the wheel flange sticks through the center of the wheel, which is how the weight of the vehicle will be supported by the wheel. The four 3/8" grade 8 allen bolts only have to hold the wheel flat against the flange, the center part does all the real "work".

The gnarly-looking crud in the center is where I welded the axle to the wheel flange after pushing it through the tight hole I bored in the flange.

Pic 3: Here is the flip side - the back side of the tire/wheel with the wheelflange/axle assembly bolted in place, all the bearings, tapered cups, and the aluminum spindle in place. For my entertainment I gave it a good "whirl" and took a picture. It spun and spun and spun for quite a while, almost a minute.

The suspension arms (which I haven't made yet) will attach to the aluminum block. That's coming up real soon once the steel arrives to make the arms.

Pic 5: For a steering column I was going to just support two bearings with a 5/8" ID and shove a 5/8" diameter round stock down the two of them and bolt on a wheel. My son asked me this morning if his truck can be like Daddy's, and have a key.

Coincidentally I saved the old steering column out of my F350 crewcab when I replaced it with a Town Car column, so I may end up using some of the guts of that column in the car. I swapped the columns to get "tilt wheel" and add cruise control since the buttons are in the horn pad. This left me with a perfectly good though ugly column. The splines on the shaft are oddly spaced and not all the way around therefore I''d be locked into Ford steering wheels of certain years/models unless I tackle machining new splines or welding on a flange for a more generic riding mower or go-kart steering wheel. I was thinking something in the 10-11" diameter range. What do you guys run on your karts?

Pic 5: Started marking up and getting ready to center drill the front wheel flanges, then drill out the 110mm bolt circle. Yes, this looks just like the other ones except in the end the center bore will be much larger.

Pic 6: The front spindles I showed you earlier are just the "kingpin" part of the spindle. As you can see there wasn't a place to attach a wheel, and this part I'm making here will facilitate that. It's often called a "spindle snout" though it has many other names.

It starts off as a 6" long piece of 1.5" square stock to which I turn down 5" of the length to 1" diameter. The square part will be "splayed" on the milling machine then welded to the spindle in the earlier pictures. Get ready, machining a piece of square stock to round makes a lot of noise!

Pic 7: Actually it wasn't that noisy as all. Why? Because I deliberately designed this part to have a larger square dimension as compared to the final round dimension 5/6th of the way down the square stock. This allows me to insert the cutter right by the live center (lower right of the picture) so that the cutting edge is just below the center of the flat stock.

This means that the cutter never leaves the material, and there is no clanging, banging, and chirping. Just a smooth cut from the far end towards the square block that remains in the chuck by design.

Of course I had the cross slide move very slowly just to be sure. I also used a brand new carbide cutter to ensure there's no bouncing off the material which would contribute to noise and wear of the lathe.

 

[frederic]

Not a very exciting or useful video, but it shows the rear spindle spinning inside the rim and tire on the tapered bearings. Nice and smooth and it freewheels for a while which indicates I got the machining right. At least it seems to indicate that ;-)

http://www.youtube.com/watch?v=HfQOvw5rUDY

 

[Rotore]

nice!

 

[frederic]

2009.09.01 - Wow, it's September already.

Pic 1: Bought square tubing to weld up the rear suspension mounts much like I did with the front. Also picked up round stock to turn on the lathe to make the a-arm ends, again much like I did with the front. I spent $38 today.

Pic 2: Low-Res of the original spindle design. I did have to change the top "ear" to a shorter dimension and I didn't update the diagram yet.

Pic 3: Milling out the back end of the snout. The snout is the piece the wheel bearings will be on, and the end was left square intentionally so it can slip "over" the knuckle part of the spindle as well as keep the bearing away from the knuckle, by about 3/8" inch.

Pic 4: The milling process is complete. This was enjoyable to machine because the cutter was brand new right out of the package, so it chipped away at the mild steel without effort.

Pic 5: The snout is ready to be welded to the knuckle, forming a complete spindle. I put a 6" machinist's ruler next to it so you could get a feel as to the size.

Pic 6: Clamped and ready for welding. Notice I wrapped my welding blanket over the snout to prevent slag and "mig balls" from landing on the snout and requring me to re-machine. Having to machine this again would be a pain because of the "ear" sticking out the back so it's better to avoid the problem entirely.

Unfortunately it seems mice have been eating my welding blanket. Since it's toxic, I hope they left the garage and are in my neighbor's garage and died.

Pic 7: Here is the spindle welded together, resting on the garage floor so it can cool off. It took about two hours to cool off enough that I could pick it up with my bare hands. My 110V 90A wirewelder is not designed to weld pieces this thick, so I had to make several passes to get things to stick together with decent penetration. This of course made the thing hot as the devil himself.

Pic 8: The spindle finally cooled off and I installed it. See, it's starting to look like a go-kart after all!

Pic 9: I'm turning the other side's front snout, and this picture shows how I did it. First, I did a pass to chip off the pointed edges of the square stock, then took a second pass to shave it even more, then a third pass which actually makes the square bar round all 360 degrees.

Here is a high resolution of the same photo if you're interested (and located on the internet in an area that I don't block due to spam):

http://frederic.woodbridgedata.com/pictures/toytruck/elec-truck-142high.JPG

I included the high resolution picture because I find "grain" in steel in the raw or cut fascinating for some reason. I just thought it was a cool picture so I included it.

One of the things that will be complicated, and in fact probably the most complicated aspect of building this kart, is integrating the Audi differential into the chassis. There are threaded mounting holes on both sides and on the back, but nothing on the top or bottom. The holes are different distances from an imaginary line drawn through the material around the hole that's the furthest away from center, which makes things a bit difficult to measure up. I put over an hour in measuring (and remeasuring) and I think I will fabricate the mounting bracketry by using the audi transaxle as a template. Once it's in place on a mount of some kind, I'll weld the rear suspension brackets to that structure, then devise a way of bolting the entire assembly to the backbone.

I thought originally I'd mount the front half of the differential on the underside of the backbone but then it's not supported enough in the back, though it would line up nicely with where the axles are anticipated to be. Anyway, it's complicated ;-)

 

[TOO FAST]

Complicated is good

 

[frederic]

Yes and no. I could weld up something quick that would work fine and be quite strong, but I have to allow for the ability to remove the side cover of the differential, or at least make any mounting pieces that cover it removable. Otherwise I'd have to yank the whole assembly out to get at the differential. That's the one disadvantage of such a large car part on a go-kart - placement.

But I have to work on that after the remaining front spindle snout otherwise I can't fabricate the rear suspension, as the dimensions of those parts hinge on knowing where the differential will actually be.

 

[frederic]

Got some work done today on the differential mount. I spent (wasted) a lot of time trying to triangulate the various oddly-placed mounting bolt holes in three dimensions however after I got a few of them done and correct I looked at the clock and this was eating up way to much time.

I decided to mount the differential to a mount that attaches on the three bolts on the tail which are arranged in a triangular pattern as well as the nose which has four bolts, spaced oddly as well. All the mounting holes on the side are to be ignored.

First, to get the nose right, I needed a template. I hacked down the Audi tailshaft housing since I have no real use for it and milled off the jagged remains so I could lay it flat on a piece of steel and locate the bolt holes correctly before drilling. Piece of cake (pic 1).

The three bolts on the back weren't difficult either because they're arranged in an isosceles triangle pattern - 4.252" on two sides and the bottom was 4.531"

In Pic 2 you can see the semi-finished mount. The top plate in the picture is only 1/8" steel and not designed to be structural but instead simply hold the nose of the differential in place. There will be other "things" on that end because that's where the motor, jackshafts, chains and sprockets will be and I'll need to beef that area up for those components, once I select them.

The bottom flange in the picture is 5/16" thick steel welded to another piece of 3" square tubing off the old exercise equipment I cut up for this project to reduce costs.

Since the output flanges will be almost inline with the backbone itself, I need to figure out how to put the wheels right in front of those flanges so there's no real opportunity for binding of the CV and U-Joints.

I'm going to do an experiment to night to see if "splayed" h-arms work well enough or I'll have to weld some more 3" square tubing around the differential so the rear a-arms can attach behind it.

This is the complexity I was talking about earlier.

 

[frederic]

Pic 1: Welded the differential mount to the rear of the backbone. Using two 1" square tubing on either side with some clamps made aligning it in three dimensions very easy. The advantage of using square tubing instead of round tubing.

Pic 2 & 3: Here I've installed the Audi differential. Now you may be wondering why it's in a vertical position rather than the more likely horizontal position. This is because of the nose of the differential (the part that's facing the ceiling in the picture) would have to go 2/3 of the way into the backbone in order to have the axle stubs centered between the upper and lower a-arms (that I've not constructed yet). I tried different positions - on top but upside down with the differential part hanging off the back, on the bottom right side up with the nose of the differential under the backbone, and each time the axle flanges would be perfectly lined up so that the axles will hit the a-arms.

In the vertical position the differential will still be "wet" as the chamber inside the housing is the same all the way around except for where the pinion gear enters. That area would normally be oiled by "splash" from the differential rotating and I'm not expecting that to occur. So, I will use high-speed axle grease to lubricate the two tapered bearings for the pinion shaft which will be fine considering the horsepower this unit is *not* going to see.

Anyway, the weight is well supported by the thick plate on the bottom and I have no worries about it bending or breaking off. The top plate is rather thin and not fully welded because I have to create a jackshaft and a variety of other structure on top and once I do, it will all tie together.

I will be welding in a pair of gussets on top as well as on the bottom of the added piece of frame and will be boxing around the transaxle with more 3" square tubing, giving me something to weld the rear suspension mounts to. A quick run with the tape measure tells me it should work out okay. If not, I can fudge some of the other dimenions a little bit to compensate.

Regardless what I weld to what (structure wise), I have to keep in mind that I cannot weld structure around the differential entirely, and whatever is behind it needs to be removable with bolts or studs.

This is why I haven't made the rear a-arms yet - because I wasn't sure how the rear end was going to look until I got the differential in place.

 

[jorge0136]

This was the first time this ever happened to me. The one lathe mistake I make often is I forget to remove the chuck key from the chuck before I turn it on. Since I run my machine in reverse most of the time so the cutting is on my side of the material, that means the key comes right at my head.

I have my own idiosyncrasies as well with machines. For example I always remember to wear safety glasses while drilling but forget when I go to grind something. You aren't alone.

Thank God for racing suits, helmets, 5pt harnesses, and a plethora of friends watching you make a fool of yourself, said friends mostly being fire/EMT types.

Just 5 years of your life and some hurt pride though right? Broken pinky, those heal up nicely I hear.

Well done on the machining, I was uncertain about the bearings just sitting in your honey comb block but now I see that it seems to work perfectly.

The milling process is complete. This was enjoyable to machine because the cutter was brand new right out of the package, so it chipped away at the mild steel without effort.

I absolutely love when I have the right tool for the job, makes projects much simpler.

Your spindle assembly looks pretty beefy, especially with the spindle itself being newly machined shiny steel.

I included the high resolution picture because I find "grain" in steel in the raw or cut fascinating for some reason. I just thought it was a cool picture so I included it.

I am at work right now where the monitor is some 22" lcd viewsonic. That picture is very cool on this screen. Easily larger than life.

Got some work done today on the differential mount. I spent (wasted) a lot of time trying to triangulate the various oddly-placed mounting bolt holes in three dimensions however after I got a few of them done and correct I looked at the clock and this was eating up way to much time.

I understand your problem here too. I always spend hours drawing it out and perfecting my math(or so I thought). Till I go and try it and everything is all off. Wasting time all the while. More recently I have been going with the think it through once and do some rough math as I go. It seems to have been working better for me since.

Those bearings ever come? Do you have the controller, batteries, wires etc.. for driving it yet?

On the steering wheel I have a 11" steering wheel in my kart and feel as though I am fighting the thing all over the road some times. I probably just need to extend the spindle arms a bit, but a larger steering wheel would accomplish the same thing. If you can find something bigger I would use it. Might be too large for the kido though.

That steering column looks like more work than it might be worth. Might be worth finding a different column with better splines off of it.

On the unsightly welded portion that you can see in the wheel spindles, you should find some old metal emblem or something to weld in place. Shoot an old tin can with something fun on the outside would hide it up fine. Merely cosmetics though. Probably worry about making the thing move about first.

Your son getting excited yet?

 

[frederic]

I have my own idiosyncrasies as well with machines. For example I always remember to wear safety glasses while drilling but forget when I go to grind something. You aren't alone.

I wear prescription glasses so maybe I take some comfort in the lexan lenses. "Unbreakable" and "unscratchable" according to Pearle Vision, however if you saw my glasses you'd know they lied, lied, lied!

Just 5 years of your life and some hurt pride though right? Broken pinky, those heal up nicely I hear.

I know, I know, I lived ;-)

Well done on the machining, I was uncertain about the bearings just sitting in your honey comb block but now I see that it seems to work perfectly.

Those aluminum blocks need more machining actually - I have to make pockets for the rear suspension arms. I just haven't gotten to it yet as I'm trying to get the front suspension done as fast as possible so I can measure the track width rather than go by my drawings. Based on how several things didn't work out as planned, I know the original diagram is off by several inches in track and length.

I absolutely love when I have the right tool for the job, makes projects much simpler.

Same here, particular sharp cutters and sharp bits, something I seem to not have a lot of!

Your spindle assembly looks pretty beefy, especially with the spindle itself being newly machined shiny steel.

It's beefy and likely to be indestructable in this application. For a real vehicle I'd have used 4340 instead of 1018 or 1020.

Till I go and try it and everything is all off. Wasting time all the while. More recently I have been going with the think it through once and do some rough math as I go. It seems to have been working better for me since.

It's not a waste of time. Having no drawing at all and winging it often results in a huge, worthless mess that you have to start over and lose plenty of time and material. Even though my drawings rarely look precisely like the end product I think it's better to have a clue. I equate my drawings to "clues" rather than a precise expectation of the results.

Those bearings ever come? Do you have the controller, batteries, wires etc.. for driving it yet?

The bearings arrived yesterday afternoon, and I unpacked them this morning once I finished machining the snout for the second front spindle. Started on the hubs this afternoon in fact.

I have a prototype controller breadboarded and it passed the initial test however I haven't gotten back to it yet because I've been so busy machining parts. I'll probably not get to it until later on.

Batteries I do not have yet but a trip to walmart will solve that - deep cycle marine batteries. The walmart by me usually has battery sales early october so the timing is about right.

Wiring will be from scratch, pieces of harnesses plucked off my shelves or out of the pile I keep tripping over.

Pic 1: the back area is where I store bigger car parts and you can also see the white wire-rack shelf with scrap steel on it. That's about 1/10th of the useful steel I have floating around as most of it's on the floor so I can trip on it. If you look under the wire shelf back in the wall area, you'll see a shiny cylinder leaning towards the left - that's one piece of a full C4 corvette suspension, front and rear. It takes up less space when disassembled Further back are two F350 powerstroke intercoolers, a few radiators, and a large pile of used brake rotors.

Pic 2: This is the pile of "stuff" mostly contains snips of automotive electrical harnesses covering various cars bumper to bumper.

On the steering wheel I have a 11" steering wheel in my kart and feel as though I am fighting the thing all over the road some times. I probably just need to extend the spindle arms a bit, but a larger steering wheel would accomplish the same thing. If you can find something bigger I would use it. Might be too large for the kido though. There's a lot of junk on top of the boxes but the boxes are two deep full of automotive connectors, wires, switches, sensors and other stuff. You can see the tripod I used for the videos leaning on the front, and a lot of my smaller power tools that are in cases scattered around the floor.

Pic 3: This is the "staged" automotive parts section, most of which are going to be part of the twin turbo BBF stroker for my F350 crewcab.

So yes, wiring will not be a problem ;-)

That steering column looks like more work than it might be worth. Might be worth finding a different column with better splines off of it.

Yeah, I'm getting closer to that conclusion as well. I was debating machining off the splines and carving out a woodruff key slot and making a machined hub for it but probably what I'll do is take a piece of 5/8" solid round stock and toss on some bearings and call it a day. I didn't think I had any more 5/8" bearings but I found a box of seven so that's probably five more than I need.

Probably worry about making the thing move about first.

I'm just trying to get it together and moving under it's own power as fast as I can, then over the winter or come spring I'll be making the body for it.

A huge factor in how long this takes is the fact that my breaker box is full to the max (100A service is the pits!) and the garage only has one 15A circuit, so this prevents me from starting a cut in the lathe and leaving the various transmissions engaged while I walk four feet away and mill something else.

Your son getting excited yet?

For sure, he askes me every day if it's done yet and makes a prune face when I say "not yet handsome". He wants to help in the worst way and when hand tools are involved I of course invite him into the garage. Last spring/summer/fall my son was turning the various cranks on the machines to make cuts (with stops installed to avoid ruining the part) however this year he's not been paying attention enough to safety so I had to put the brakes on unfortunately. I want him to have the 10 fingers he has now. This year his curiosity outweighs his willingness to listen to safety reminders.

What's neat is I finally picked up all the contractor bags of "machine chips" to take for recycling center. I weighed one bag and it's 55 lbs, so assuming they're all the same tomorrow I'm unloading 565 lbs of chips lol.

 

[frederic]

Back to machining parts for the front. Here is the start of a front hub.

Pic 1: drill a hole down the center.
Pic 2: enlarge hole with boring bar while drinking coffee.
Pic 3: machine indentation for tapered cup.
Pic 4: finished one end. Now to turn this around and do the same process for the other side.

Pic 5: Finished welding the other spindle. I have about 20-30 minutes of grinding to do to blend the beads in well enough I can stand to look at it. It's very difficult to get decent penetration with material this thick with a 110V welder, however if one goes real slow with the current on max and lay bead on top of bead one can fill in the whole area "good enough". For a full size vehicle I'd use my other welder which is 240V for oversized kart parts ... naaaah ...

Pic 6: Just in case I didn't post a picture of the new tires and wheels I got dirt cheap off ebay.

 

[brendonv]

I have no idea what any of the things u make in the pictures are for but it looks awesome. I love the progress shots of people machining things.

 

[frederic]

I have no idea what any of the things u make in the pictures are for but it looks awesome. I love the progress shots of people machining things.

Once these individual pieces get welded together and look like a finished part, it will make a lot more sense... trust me!

I'm just not quite there yet.

 

[frederic]

Okay, enough progress has been made that things may start making some sense.

Roller collar (pic1) plus wheel flange (pic 2) = Front wheel hub (pic 3).

Pic 4: tack welded the two together as precisely as possible. Since welding shrinks metal the first tack resulted in the wheel flange shifting a bit so I had to place a piece of steel bar stock across the nose of the collar and use two clamps between that and behind the wheel flange to torque it into place, using a dial indicator before and after. I was smart enough (for once) to measure the distance from the face of the wheel flange and my lathe's cross-slide with the dial indicator first, and I noticed it pulled towards the weld 0.117 inches. So, I wrenched the wheel flange forward half that measurement and made two more tack welds hoping for the best. Seems my guess of halving the measurement was reasonable because the face of the wheel flange wobbles less than 1/100th of an inch. The tires aren't even close to being round within that measurement so this is good enough.

And yes, I do know I have to run beads around the perimeter. I just ran out of time before having to pick my son up from school.

Cool, huh?

 

[Kaptain Krunch]

I'm not gonna lie, i had no idea what was going on for the last page, but its all making sense now haha. Looking good, seems strong enough to last your son quite some time. Maybe a bigger gas engine when he gets older?

 

[freakboy]

I think a v8 should be in order or a 440 sled engine!

 

[frederic]

Minor progress today.

Pic 1 - Threaded the nose of the spindles for a nut to retain the two bearings and the hub. Normally I'd cut threads on the lathe however since I forgot to do that while the snout was still chucked in the lathe, re-chucking it would have been a pain in the butt since there's a spindle welded to it now. So, I pulled out a 1" tapping die and a large die crank and tested my upper body strength. While very tough to turn, I had more problems with the vice not keeping still. No matter how tight I made the swivel on the bottom of the vice, it would eventually move. So, I did what any pissed off car guy would do and welded the vice to the base. It's just a 3/8" wide bead on one side so if I ever need to rotate the vice again I'll just grind off the bead and it will be fine.

Pic 2 - I couldn't find any 1" nuts anywhere today so I decided to make my own. I certainly have enough steel lying around so I pulled out a piece of 1.5" round stock, drilled a hole, then shoved in a very small carbide boring tool and carved the inside diameter to a hair over 7/8", the dimension my tap and die drill chart suggested as "ideal". I went a hair over because it makes it a little easier to start the 1" tap.

Pic 3 - I set my lathe into "backgear mode" which means the chuck turns at about 10 RPM tops, or something in that ballpark. It's great for cutting threads but since the threads are on the inside diameter and the cutter I'd normally use for this type of work couldn't be found I decided to use a 1", 8-TPI tap and clamp that into the toolholder on my cross side. I set the lathe's transmissions to move the slide at the appropriate rate to cut 8 threads per inch, so the cross slide fed the tap into the material at the precise speed it needed to be to cut nice threads.

Pic 4 - Here I'm cutting off the "nut" off the round stock using a parting tool I cut myself. While these little details might be boring for some I figured some of you would enjoy seeing the little details like the parting tool. If any of you buy a new or used lathe for your projects, you'll be making tooling like this quite often. It's far cheaper to make your own than buy the overpriced holders and specialized tooling that goes with them.

Pic 5 - And the "nut" fell off into my "catch bar". It's nothing more than a piece of round tubing that I shove into the tailstock and crank into the center hole of what I'm cutting off. Why? Well, sometimes the part you cut off falls straight down into the chip tray. Other times it bounces off the cross slide and flings itself behind the lathe on the floor where you can't get at it without moving the 2500 lb lathe and lathe table. Much better to use a catch bar

Pic 6 - the nut has been threaded down onto the spindle, clearances checked, and it's nice and tight yet the hube and wheel flange that are welded together (pig welding!) spins freely without any obvious play.

The next step which I'll get to tomorrow hopefully is to machine the nuts so it has two or four flat edges where I can use a wrench to loosen or tighten it. I also have to cross drill for a cotter pin for nut retainment. Do not want these things to fly off!

 

[frederic]

2009.09.06:

Pic 1 - While the lathe was automatically boring out the center of the second wheel hub I decided to fit all the parts for one front corner to double check the caster and camber, then followed with installing a wheel/tire to see what I have.

Not bad. It does look like a tire suspended off a chassis. Cool.

Pic 2 - If your girlfriend, wife or mother asks why you spend so much time in the garage "playing" remind her that you are not only enjoying your hobby but you're also getting a full body workout. It beats going to the gym any day!