Category: Überclocker

30lber Clampbot project

Ãœberclocker update 7, LOLriokart update 4

chorl1 Comment

A wonderful weekend of work kicks off with major progress on Ãœberclocker and a bit of work on LOLriokart!

More to come after I wake up at 3PM today…

Übercløcker

The first order of business was to construct the back end of the bot, which acts as the alignment device and reference plane for the entire rest of the bot.

This was a bit of tricky business, since the piece of UHMW is 20 inches long. The Bridgeport mill has…. 20 inches of table travel. A bit problematic. And I only had one non-dysfunctional vise (The other one, shown on the right, is a cast iron Swiss cheese sculpture)

The partstopping angle plate came in handy this time, since it allowed me to shift the UHMW bar left and right to known locations so I didn’t have to edgefind every single time I needed to perform an operation on a section out of reach.

In this episode of Improper Machining Techniques 101, how not to support overhanging work pieces! This is a machine parallel duct taped to a smaller angle plate duct taped to the table, all shoved under the section of UHMW.

This was too sketchy even for me, and so I ended up switching to some of those step clamp blocks. The duct tape couldn’t hold the vibrations of milling slots.

About this time, the Y-axis readout started funking out, losing its value every few passes. This caused a headache really quickly, so I dismantled the slide to find out if something was loose or not.

…. I’m not sure if this is how it’s supposed to be wired, but obviously it’s beyond my level of knowledge. I secured the cable to a similar level of build quality (zip ties!) and tightened the mounting screws (which were loose – likely the source of the issue) and the hiccups stopped.

After some more fiddling with working on a 20 inch part in a 20 inch workspace, here is the completed back rail (without countersunk holes yet). The piece is actually not straight due to UHMW’s tendency to warp while machining (and its naturally warped state). It has a roughly .020″ bow over the longest dimension, which means one side is slightly shorter than the other.

The critical dimensions don’t depend on the actual part height, so it’s not a loss.

Next up were the side rails. To save time and sanity, I set up the angle block as a partstop and clamped all the rails together to be processed (at least, drilled) as one piece.

I decided that this was going a bit too far, since 2 inches of material is alot to ask of any drill bit and totally out of reach of the smaller bits. So I split the rails into left and right sides and proceeded with a setup similar to the picture.

Midway into Saturday evening. All four side rails are processed with the major features (no countersinking or slots, which will come later), so it was time to arrange a test fit & sanity check.

This also included fitting the spring-loaded front support legs and testing them out. Verdict: Pass, but final testing is required. If I ran my calculations correctly, the bot should move over the 1/4-3/8″ floor hazards at Robot Battles with ease, and should balance 30 pounds on the end of the clampfr0k with the springs at full deflection.

I actually managed to lose the other spring, so I’m ordering a handful from McMaster.

After some more hours of work making matching axles and spacers for the newly created left side, it was time for another episode of Pretend-o-bot.

This episode of Pretend-o-bot shows the milled sides and back rail, with the two existing wheels fully mounted and the front supports (mostly) in position. The final bot is taking shape very well. What’s not shown is the almost mirror-like finish of 1500 grit sandpaper on the axle spacers. After all, I can’t photograph through wheels.

I expect some assembly of the frame parts today. Now I’m only waiting on another shot at the waterjet cutter (which may or may not still be mad at me)

Ground clearance check. Chassis: 7/16″ (with baseplate). Front supports: 3/16″. The bottom of the supports might be beveled inwards to allow traversing of the floor hazards.

This is another one of those DUI (Designing Under the Influence, usually of -3 hours of sleep) aspects of the build… why on earth did I make the forks stick out for their entire profile as opposed to only the tip?

What’s left on Ãœberclocker? A bunch of things. All the side rails need their slots and other features to mount the motor. I need to build two more “inner-inner” pieces to hold the back ends of the motors. All countersunk holes need countersinking. The fr0k needs workable parts and final assembly. The fr0k drive needs to be built (actually, it needs to be completely designed first!). I need to make a few more little widgets. Then everything needs assembling.

That’s just the mechanicals.

LOLriokart

Work on LOLriokart Friday evening was focused on overcoming the steering and brake issue. I’m proud (can I really be proud of such an abomination?) to say that this has been solved, so work can shift to the back end to hook up the drivetrain goodies.

Here’s an overview of the progress.

I now have the other half of the steering joint. The assembly is rather simple – a large steel bolt retained by an aluminum block, which has a crossdrilled hole to fit over the steering kingpin.

The additional holes on the front of the pivot block are to mount the actual steering linkages when I get to them.

This is the pivot assembly. The aluminum block has a 1/2″ ID bushing on the top and bottom, and a big 1/2″ cap screw with the head cut off is mounted in a hole. This cap screw will be the front axle stubs, and both the brake and wheel/tire will mount on this.

The cap screw shaft has a big flat machined onto it that is captured by two 1/4″-20 screws. Yes, I’m holding the axle on with set screws.

Famous last words, or a potential Loctite sponsorship?

Wheel mounted for a test fit. These cheap handcart wheels have no internal bearing spacer, unlike roller skate and scooter wheels, so the compression force provided by the axle nuts has to be just right or it will seize. Or wobble. I will probably make an internal spacer to save the trouble.

Front view, showing a profile of the assembly. The Brake-O-Hubâ„¢ extends into the band brake. The brake body itself simply slides over the 1/2″ axle stub, and the arm that sticks out the top will be retained by a bracket to the pivot block. This is why the block has those two little holes on the top surface.

A little spacer keeps the Brake-O-Hubâ„¢ the correct distance from the brake assembly when the axle nuts are tightened.

And in a slightly serendipitous moment, I find that I actually do have an assload of steering travel. I think this is about 35 degrees, and that’s on the more restrained (due to the shape of the cart bottom) side. Looks like the steering arms are going to be pretty long to take advantage of it.

That’s it for now… Work this weekend will probably be concentrated on Ãœberclocker instead of LOLriokart, since I do want to extend my life as long as I can.

Bot on?!

Ãœberclocker Update 6: The Beat Goes On

chorl

It’s been a while since I’ve had an entire day of solid bot work. Most of the “weird machining” on Ãœberclocker is now either in process or over with. A few tricks and workarounds made things go alot faster.

…like this one. After exactly one part, I got sick of having to re-zero the machine after flipping the piece over. And so I had to devise some crazy rigged solution as usual.

Fortunately, this time, it wasn’t too rigged. A few 90 degree angle blocks were hiding in a shelf corner, so I cleaned the industrial grunge off one and mounted it to the mill table. A bit of threaded rod and some malleting later, and I had a makeshift “workstop“, which is a little stick-like thing that is used to accurately reposition a workpiece after removing it from the vise.

It’s slightly more than a stick, and looks like it can actually stop a small train, but oh well.

How do you drill a 9 sided hole? With a countersink. Although there were a dozen or more countersinks in the Toolgasm, none of them are odd-fluted. The result: chatter like Paris Hilton with a new cell phone.

It probably didn’t help that I just freehanded this part.

Fr0k spacing things all threaded. The same part that got me sick of edge finders also got me sick of manually tapping. Solution: spiral-point tap and a cordless drill. Spiral point taps seem to be an order of magnitude stronger than their four-fluted hardware store cousins, clear their own chips, and a nice handful came with the Toolgasm. I selected a TiN coated #10-24 and tore through all 24 threaded holes in a few minutes.

Unfortunately, 16 of those ended up needing to be clearance holes. Oh well, better that I thread 16 extra holes than drill 16 holes too large.

In another fit of absurdly industrious machine work, I finished up the “upper fr0k”. To my chagrin, I discovered that 800 grit fine sandpaper produced the same shiny finish as a fine power feed. So I just made a bunch of standoffs from raw half inch aluminum stock (of which there was a convenient 10 foot stick, found behind yet another unsorted shelf). The front support leg standoffs were made this way. I decided to not bother shining up the spacers for the upper fr0k.

These were also power-threaded with the same #10 tap, on the lowest speed setting of the lathe (something like 100 RPM). I set the belt tensioner a bit loose such that when the tap bottomed out, the spindle stopped turning.

Outer fr0k tines mated to their respective spacer things. The 15 degree lead angle on the spacers have been milled in this picture, and is just barely visible (They won’t do a thing… why the hell did I even design those in?)

After putting down the fr0k, it was time to attack the first “weird machining” task – making the 10 degree front and rear slopes. This was made decently difficult because the parts were huge (15″ long UHMW) and I had no angle blocks, angle vise, angle plates, or any other implement with the word “angle” in it besides “angle grinder” which didn’t help one bit in this case.

I ended up pulling the same stunt as when I machined the 45 degree front slope for Pop Quiz – tilting the head and using Interesting Trigonometryâ„¢

It worked pretty well. For every n” I moved the table up into the cutter, I had to move the x direction n / sin(10°) to keep the cutter face on the same plane. Repeat k times for k a small real integer constant and a 10 degree slope emerges. Then flip the part over and do it again.

After all four rails were roughly shaped, it was PRETEND-O-BOT time! Hey, it looks like something.

This thing is absolutely enormous. That’s a 36 inch T-ruler I used to position the parts. The chassis itself (UHMW only) is 15.5″ long and 20″ wide. The fr0k extends way out in front and brings the total length of the bot to 27 inches. That’s pretty nutty. For comparison, TB4.5MCESP1LOLBBQ is exactly one foot square (one square foot?!) with the wedge bringing it to 16″ long and 16″ wide.

While I was still on bot-gasm mode, I trimmed off some of the 1″ UHMW barstock for the back end. Also notice the similarly-sized aluminum bar. I originally purchased this for the LOLriokart (whose drivetrain parts are still in transit. Thanks goes out to Bank of America for assuming any purchase I make over $100 is some kind of fraud unless I tell them beforehand that I’m buying something more than lunch)

I’m debating whether or not to just make the back end of the bot out of aluminum. The bot is 7 pounds underweight in the design, even with most of the big hardware accounted for. Since there’s no way I can fill up at least 6 pounds just with wires, Loctite, and duct tape (by accident), it could stand some more solid material. Aluminum would also double as some ballast to keep the bot on the ground during a powerlift.

Stay tuned for more! United Hobbies/Hobbycity should be pitching some 4AH lithium polymer packs at me soon.