Gas Tank Mount Pockets

Curvature added to the end to match ripe up to the profile of 13 gage tank tunnel that Fab Kevin hooked me up with. It will make sense when it is all mocked up and ready to be welded together.
Inside view, added R0.063 fillets to the interior corners for added strength. These will be welded into the bottom of the gas tank and sharp interior corners are a huge no no as it creates huge stress risers. Added a R0.125 to the top edge for a smooth look when in the gas tanks. Round corners are also less like to pop paint off. Same steel here, 1018, low carbon mild steel.
Gas tank mount pockets. Design these from scratch to match up with the tabs and grommets and tank so that the bottom of the gas tank will be even with the bottom of the top tube on the frame. Gives a smooth line of the frame and bodywork in the end. As a result of this i had to machine some pretty deep pockets. The thru hole and .020" deep pocket are for a threaded bung that i will weld on later. Decided to make them 2 part rather than dropping some coin on 2.5" thick steel just to machine it mostly away.

Gas Tank Mount Tabs

Tank mount tabs done. The large hole is too accomodate a rubber grommett for vibrations dampening. 2 different length tabs becuase the tank is wider at the front and the longer tabs will provided more stability and allow less tank resonance and vibration at speed. Reducing the chance of failure and getting a lap full of gasoline sitting right over a smoking hot air cooled engine.
Profile complete and the width is set. The 'fishmouthed' end of the tab will wrap the top tube of the bike. Commonly the tab is just flat stock, butt welded to the top top tube. Rigid choppers, like I am building, are vibration nightmares which like to break the welds on gas tanks. I wanted to get a wrap too the top tube that will also allow me to spread my weld over a larger area, adding a lot of strength and sending the vibration forces into the thicker radiused corner.
Op 1 complete, flip them over and finish them off. You can see below that i don't have much meat left in the vise to hold onto. I would have like a thicker piece of steel such that i could machine the profile to height, then flip it over and run a face mill to finish the overall width of the tab. Bigger pieces of steel cost more money, so i got a piece the is right to size. Just had to make sure I located it accurately so there is no mismatch when machining the same profile from 2 different sides.

Start to finish gas tank mount tab machining. Off the shelf 1018, low carbon mild steel stock. Cut to length, design set and programs loaded. Let's make some chips.

Front Axle

Entire front axle assembly in place. I need to take approx .050" off the front brake bracket to push the caliper towards the lower leg and this make it centered over the brake rotor. Check this off the list. I now have a full roller, with the spacing and brakes set. Gas tank next.
Spacer in place over newly machined axle, nut torqued down.
Here is how the nut looks on the lower leg. I am happy that it looks like it belongs. The flange of the nut matches up nicely with the boss landing.
So here is the axle I machined. Well actually Kris, the BAKER Machinist did this one. I can't run the CNC lathe like he can and I just wanted to get this part done, rather than taking the time and wasting the material (think money) while trying to learn more. Axle is made from: 4140 alloy steel, 28 rockwell C, pre-heat treated. Yields the strength and stifness that I need. This axle is different than a stock softail as my design has nuts on both ends. The stock H-D softail axle has a knob on side with a hole to place a drill through while torquing the front axle. It is a design befitting a lawnmower at Wal-Mart, not a custom bike.

Front Axle Nuts

Being that I was trying to get the nuts to be as narrow to the lower legs as possible, for the minimalistic look, I needed the tapped hole to be flat bottomed. After machining of the top 'divot' and the fully threaded hole, I only have .065" of material between the two features. I peck drilled the 3/8" drill to just short of the .700" full thread depth I needed. I then used a 3/8", 4 flute, carbide end mill to open up the 37/64" dia c'bore that I need to run a 5/8-18 flat bottom tap in there. The nuts got threaded, chased again with the tap to ensure good threads, and then deburred waiting for the axle to be lathed.

Top view to show a better view of the 3-d machining that we did. They look sweet, like something off an F-1 car. Stainless sucks to machine and it\s really good at cutting your hands when trying to deal with the edge burrs and the chips, but it looks awesome machined with good carbide cutters. I know that many of your thinking, well that looks like a normal nut, why did you spend the time and money for material to make it, rather than buy it. Becuase you can't buy this nut anywhere. Most flange head nuts, are through threaded, not blind this design. Most nuts have a smaller aspect ratio of the ID thread, to hex size to OD than this. My design is the perfect fit for my bike, and that is all that I want in the end. I don't care if it takes a long time to design or make. I won't cut corners on my projects.
Axle Nuts in process. Started with that 1.625" dia 303L stainless stick. Programmed the 3-D milling with the help of Chad (BAKER Design Engineer) and Kris (BAKER Prototype Machinist) using Featurecam. Cut some slugs off of the stick, Kris milled some round pockets in the soft jaws of the small haas, and we knocked out the hex nuts to the state you see here. Note how the nut in the vise has a much smaller flange thickness on the bottom. I have already used a 2.5 dia indexable cutter to face it to the final .800" height. The other nut is next for a haircut.

Sprocket Spacer

Looks good because it all flows together like it was designed for this bike. When I do final assembly this will look even better yet. Some high grade fasteners, stainless safety wire, some real race car/bike stuff.

You can see the spacer snout sticking out here. Will look a lot better when I whack that off a little.

Sprocket spacer after a few hours at the mill. Lots of chips ended up on the floor, but it is hard when working with scrap, to get blanks that are fitted to the final part. I ended up having to space out the sprocket .390". After final fitment, (in the next couple of pics) I see that I need to face off about .050" from the end of the sprocket locating snout on the spacer. That's an easy 5 min task on the lathe.

Found some scrap in the shop that would suffice for machining out a sprocket spacer. Some aircraft grade 6061.

Another view, same spacer.

So here is what the left rear wheel spacer looks like in place. Kind of weird looking but I knew that I was going run a sprocket spacer to get my trans sprocket and wheel sprocket in line with each other while maintaining the rear wheel centered in the chassis. So I designed in the step to match up with the face of the sprocket.

Rear Brake In Place

So I have had this rear brake caliper on and off the bike, probably 15 times. My best guess is I will do that another 8-10 times. What you have to do if you want to get it right rather than 'close' or 'that's pretty good'. Caliper pictured in it's final resting spot. The bracket that gets welded to the frame will mount on the bolt closest to the frame tube in the bottom pic. Kind of a shame to hide all the work behind the frame, but it still looks sweet and unlike any other set up I have seen to date.

Rear Wheel Spacer Install

I test fit the wheels spacers, well at least the rear ones and they fit great. I still have to turn up my new front axle on the lathe before I can fit the front spacers. You can see in the last picture the mating line of the rear brake bracket to the wheel spacer. This is what I wanted it too look like, a smooth transition from the brake bracket to the wheel spacer to the wheel. Small .050" or so air gap left between the spacer and the brake rotor which is necessary. The bolts are hardware store mock up ones, they will be replaced later with stainless hex heads drilled for safety wire.