Gas Tank Fill Spout

Here is the finished product. Looks like one tube, just as intended. Kris knocked down the welded on the lathe and left it .040" or so proud of the final surface as I planned on hand finishing it. Trying to grind a round tube, any smaller than 6" in diameter is a nightmare. It is very hard to not make the tube 'notchy' from grinder passes. So I chucked it up in the lathe turned it at 190 rpm's and then used a 2" 120 grit to grind the weld flat to the tube. This trick helped me to get a perfectly round tube, that it completely seamless and no one can tell by sight or feel that it is 2 pieces welded together.
Another view, pre-clean up.
Welded it up over lunch. Tacked it around the diameter by skipping around to prevent over heating the weld seam. Then stitch it together between the tacks. That is why you will see a variation in the heat line, thickness and style of weld.
A perfect fit, it makes the welding a breeze. I don't have to worry about the 2 parts slipping out of alignment as I work the bead around the diameter.
I bought the cap and matching steel bung from The Chassis Shop. A race car chassis parts company based in Silver Lake, MI. They are either partners with or own Pro-Werks as well, the company the cap. Both for aesthetic reasons and function, I wanted the gas cap to be 2-2.5" overall height off the top of the gas tank. So I need a piece of pipe to weld to it that is the same diameter and will look seamless like one piece of tube. I was lucky to find this chunk of old steam or water pipe that was just .100" over the diameter of the pre-made steel bung. Tom 'Tweaky' Peek turned it down for me when he still worked at BAKER. I have had it for 2 years. Kris added a small counterbore to it, as the bung has a .060" tall lip on it. This allowed the 2 pieces to align perfectly to each other before I welded them up.

Tank Mount Models

A section view right through the middle of the mounts to give a better idea of how it all works.
Here are the computer models that I created to make sure everything laid out just right. I use Solidworks for almost all of my designs. It may seem like overkill, but this whole design took me under an hour to calculate and model everything. Make assembly a breeze as a result.

Gas Tank Pockets 2

I forgot to clean off the threaded bungs with lacquer thinner before I machined them and I pretty sure that is why they turned blue. The bluing was only surface deep and I did not put that much heat into the weld. They had oil on them from anti corrosion coating from the mill, as well as an extra concentrated cooling solution in the lathe. The welds will not be visible once I weld the mounts in the tank, all I care about is that they don't break and/or leak.
Double checked that they fit good, and got the welder fired up.

For both cost and ease of machining reasons, I made the gas tank mount out of 2 pieces. It didn't make sense to waste all of that material for machining. I added the .020" deep counterbore to ensure the threaded boss would be center in the threaded hole for alignment ease during assembly. Allows the 5/16-18 bolt to have over .700" of full thread engagement. Plenty for strength and a decent safety factor.

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.

Rear Brake Assembly Models

Here are the models I created to ensure everything fit together as a unit. I felt it was necessary as I am using parts and pieces from multiple different companies that have never been put together how I intended to do it. It's funny how it all works though. My models like all scientific but when I opened the file it was all misaligned. So either my models were off or I measured the parts at home wrong. Oh well, that is part of the deal. I will check it out when I get home to verify everything.

Front Axle Assembly

Here is my front axle set up. Pretty straightforward except for the fact that I making every part. Most bikes built out there use a stock style front axle that slides in from the right side of the bike. and has an ugly flange nut on the left. I laid out the tire the tire and widths of the lower legs to give the right amount of crush on the front wheel spacers. Spacers are aluminum, axle 4140 steel. (think hard steel that won't bend) and the nuts will be stainless. Every nut, spacer or bracket really matters too me. It is easy to look at a bike and see that they used a certain part becuase it was on hand or easy to use, becuase doing it right was too hard, expensive or beyond their available resuorces.

Wheel Spacers

Here are the wheel spacers. At the most basic level wheels spacers can be tubing, cut to length. Well, I have always thought that looked unfinished. I don't want to see the seal and bearing in the wheel. I always noticed it right away, so I would think that other people do too. Small end of the spacers to the outside, big end of the 'bell' towards the wheel. There is a small diameter boss to the inside that lands on the inner race of the wheel bearings. The major diameter covers the seal and flows into the wheel. The really short one stacks up with the rear brake bracket to set the wheel spacing. These parts are my first venture into CNC lathe work. I wrote the program, set up the machine and ran them. Kris (BAKER Machinist) helped me throughout the entire deal.

Front Brake Bracket, Better Pics

Better pics to show what it going on with the front brake bracket. I drew it up on Solidworks, machined it on the Bridgeport. 2-D machining, nothing fancy. Built the necessary offsets to center the caliper over the rotor into the bolt bosses. The H-D lower shock legs that I am running have pressed in stainless washers for the brake boss' to help maintain shape over time from the stress the caliper put on the legs. The bolt boss' on my bracket fit down into the counterbores's where the stainless steel washers reside. Probably doesn't make sense in text form, simple simon if you were here putting it on.

Rear Brake Bracket

Mulitple views of the rear brake bracket I made. Looks like a complicated piece. I spent a lot of time laying it out such that it would wrap the frame as much as possible and be somewhat hidden underneath the right rear frame point. The radius angle matches the same angle as the right rear frame tube that comes off the axle block. The offest required to get the caliper centered over the brake rotor is built into the brake bracket.

Slight adjustments that need to made will be accomplished with stainless steel brake calipers shims. Completely common when dealing with one off parts and paint stackups.

I will machine a brake tab out of stainless that will use the front most brake caliper bolt for a sanitary design. I will later weld it to the frame. I am using stainless so that I can grind the powdercoat off it and then be able to slide the caliper fore and aft with the rear wheel for chain adjustment. It just looks like shit when you see rings in the paint or powdercoat from the brake bracket being slid around.

I machined this on a 2-D CNC Bridgeport. I designed it such that I could use common ball mills, end mill and bull nose end mills, but making it function as a 3-D sculpted part when it fits in the bike. Spending 8 hours to design this bracket and 4 hours to machine it are worth it too me. NO ONE ELSE in the entire world has this same bracket to mount a sport bike caliper on their chopper. That's good enough for me.

Front Brake Bracket

I don't know that these pictures do the front brakes justice. Or maybe they do. H-D lower fork legs, Tokico Brake Calipers off a Suzuki GSX-R 750 Crotch Rocket and the brake bracket that I designed and machined to bolt it all together. I will post some Solidworks images of the bracket to help show the bosses and 'furniture foot' reliefs that I machined around the edges of it. The Socket head bolts are strictly for mock up. I am going to run hex dimple flange head bolts that are used on Moto GP bikes. Pro-Bolt of out of England is the place for these bad ass bolts.

I chose the Tokico calipers becuase they are proven, race quality piece. No worries about function or finding replacement pads down the road. The are cheap too. Fabricator Kevin hooked me up with these. He makes some pretty slick, shaped steel brackets, but the machined aluminum ones will match better with all of the parts that I am going to make.

11.5" dia Performance Machine brake rotors front and back. Blanchard ground 410 stainless outers, 6061 Aluminum centers.