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Maximum Bubble Mods - Spirit of Motion

Josiah Fast

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Back with an update on the build!

It is time to start working on the grill portion of the build again. The spine and individual grill pieces were all filed to fit one another tightly the last time I worked on the grill. So before I can weld them together I need to polish the top, bottom, and back of each grill since it will be impossible to do this after welding.

I started with the inside of grills. This doesn't need a full polish so I went ahead and left this all a brushed finish. The grit was 120. I used some bee wax on the sand paper every once in a while to really extend the life I got out of the paper by limiting how much it gummed up (If you have sanded much aluminum you know the struggle I'm talking about). I was able to get all the sanding done with a single sleeve.


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Because most of the material I'm sanding is only 1/4" thick I grabbed a couple pieces of wood to use as spacers so that I could utilize as much of the sleeve as possible. It did make the process a little bit slower but I didn't want to waste so much of the sleeve.




I think it will be almost hard to notice that the inside is not polished like the rest and it saved me a tremendous amount of time by not having to polish out the additional material.


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Time for the real time consumer work of getting these ready for welding. Polishing

The fronts will all be shaped and polished after welding and assembly is complete so I just needed to polish the top and bottom of each grill and the complete spine.

I started by doing some some prep with both sand paper and some of those fiber discs in a die grinder. It was 150 grit paper (wet sanding) and the discs were medium and fine grades. The aluminum is the cheapest 6061 I could get so there are some defects and scratches that needed persuaded out.


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Next up was hours and hours of work at the grinder that don't lend themselves to interesting photos very well haha



After some testing I had to make a choice on how far to take the polish because you can really lose yourself in days of polishing if you commit to a mirror polish and so many pieces. Since you will not see direct reflections on the top and bottom surfaces of the grills I could also not worry a tremendous amount. I settled on a polish that gave me a reflection of something like a blurry mirror for these surfaces so I used a spiral sewn sisal buffing wheel and black emery polishing compound. The outside surfaces of the grill will get a more serious polish.




Because of the cheap aluminum and some damage from the waterjet cutting, there are some small marks and scratches on most of the pieces that are just not going to come out unless the piece was remade. I honestly kind of like them as they look a ton like mild pitting and marks that you see on old chrome! They will give you the relief of not crying when the computer is whacked or scratched later in life lol




I 3D printed some little spacers so I could load these polished pieces into the spine and hold them all at the appropriate spot. These will hopefully hold up the the heat of the welder long enough that I can get tack welds before they soften.

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I only assembled up the this point because I need these welded first. I can then shape the ends of them to match the curve of the main case body.

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Alrighty, I got the chance to use a welder so I could tack all the lower grills to the spine. I am not skilled at TIG welding so this isn't what good welds look like but they are effective all the same. I would really like to get more practice TIG welding aluminum!

I put the 3D printed spacers in and they worked only if I tacked the grills pretty quickly. If I heated the grill much the PLA plastic would soften which wasn't a huge deal but was annoying as I had to check my spacing periodically. I don't want to have to be bending my welds into shape later on.




Once I got the top of each grill tacked to the spine I could lay the entire assembly down and get the under side of each piece as well. (The weld with black around it is because I touched the tungsten to the pool of molten aluminum right as I was finishing my weld. The weld is fine)


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Edited by Josiah Fast
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So with the lower half welded I need to shape the ends of the individual grills to match the contour of the main chassis.

The 3D prints didn't hold up to the heat of welding well and they deformed a little. My spacing between grills is 1/2" and 1/4" conveniently though so I cut some scrap MDF I had into little squares to use as spacers between each grill.




I set up some foam to hold the assembly upside down and fit the MDF squares into the grill followed by painters tape as a clamp, squeezing the grill tight. The lower most grill had a weld that needed to simply be filed flat before shaping the contour could begin.


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I measured the height of the half grill with the spacers and it measured over sized unfortunately at just over 11-3/8". It should be 11-1/4" to match the main chassis height so I set to sanding each spacers just slightly to lover the overall height evenly. After a round of sanding on each side, the height was nice and the grill fit nicely over the chassis.








With the spacing all set I slid the half welded grill along side the chassis, placed my grill end cap (this is what the grill ends will be welded to), and traced the curve along the face of the grills so I could simple grind them up to those lines for a nice tight fit.


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Edited by Josiah Fast
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I started the shaping process with an angle grinder that had a flapper wheel attached. It was 40 grit I believe. It wasn't fun and felt clunky to handle so I was uncomfortable, thinking I may mess up since the wheel didn't grind very predictably.




So I switched to a belt sander with some 60 grit paper and it went much better for me. It was a little slower I think but I felt like I had more control over the material being removed and it felt a little safer to boot lol











It is coming along and it is great to see the build emerging!

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Before I continue welding I want the hinge and back plate to all be attached. I want to ideally weld the upper grills to the back plate with it attached to the main frame. This way there will not be the chance of misalignment of the grill to the frame once its is welded fully.

I picked up a pretty beefy hinge because it needs to be able to have some large screws hold the grill to the frame securely and squarely. The air spring is going to be in the ball park of about 80 pounds of force pushing the back plate so I want a nice sturdy hinge and screws.

The low profile piano hinge I bought was too long so I cut it down the 8" width I need and filed the ends square.




I then closed the hinge and drilled my holes to fit a 10-32 screw (I should have used 10-24 as course threads are usually better in aluminum).

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I threw on a single flute, 82 degree countersink and simply drilled down until the head was below the top face. Rinse and repeat.

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Cleaned up the deformed steel on the back side of the countersinks with a deburring tool and the hinge was good to go!


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With my hinge made up I know its actual length. I now need to notch my frame to fit the hinge's width and thickness. I notch the hinge into the frame so that the hinge is out of the way of my grill welding and to add some strength against twisting/torsion from the air spring that is off center.

I threw the frame inside a CNC mill but was just manually jogging the tool like a manual mill. It was simply the only equipment available in the little machine shop that lets me use their stuff. Using a 1/4" endmill I cut out the slot.


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I drilled the holes in the frame and upper grill plate and then tapped the 10-32 threads by hand. I used the single flute countersink to chamfer the tops of the holes to fit the screws heads. When the screws are sitting in the hinge, the screw head's chamfer stick out below the hinge so I need my holes in the frame and upper plate to be countersunk to fit the rest of the head.




I could finally test fit the hinge and it looks great! It closes a little past 90 degrees which is what I wanted. This means the grill will be able to fully rest on the frame and won't be held up by the hinge binding or not closing far enough.

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I will probably polish this hinge or paint it black later. I have not really decided yet which way I'm going. I am glad to have this fitting and working well though!

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Quick update on wrapping up the back plate for the upper section of the grill. This is the piece that the upper grills are welded to and the air spring is mounted to.

I needed a shouldered slot for mounting the bracket so that I have a little bit of adjustability in terms of height. Quick layout, drill, full depth slot, and them the roughly half depth shoulder slot.


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I also had time to tackle welding the outside edges of the grill now that is was shaped to fit. I used a big chunk of aluminum to hold them down and lined each grill up one at a time to be flush on the outside. Align grill, weld, align grill, weld...


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The MDF spacers and tape got a bit toasty (caught fire a couple times) but held up really great and maintained my spacing for the welding.

It was going really great until the ends of each side. I used a small clamp to hold the steeply angled grills up against one another before welding. On the first side I tried I put just a little too much heat in the 1/4" aluminum strip and with the weight of the clamp hanging on it... it fell right off and onto the floor.




Devastated by the horror of seeing my grill now in more pieces than it should be I sat there and took a break for a bit. After I psyched myself up, I put the clamp on the other side to keep it tight, and this time I attempted to weld it with less heat. Clanging metal rang out shortly after watching the piece fall from my helmet's small, tinted window haha



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I walked away, drank an ice tea, then returned. I REALLY took my time and slowly repaired the damage I had done. First putting tiny tacks on the pieces and then building it back up. With that fixed the lower section of the grill is completely welded.


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