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1940 SS Knucklehead: People's Champ 5 Build"

118K views 327 replies 63 participants last post by  Rigidspeedtwin 
#1 · (Edited)
OK, I know a lot of you have seen my girder fork thread, so a bit of this is rehash, but I wanted to get some of this stuff on here chronologically. If you read the fork thread, you can probably read the beginning of post 1 and then jump to post 4. I posted this over on another (the other) forum that prefers angle grinders to machine tools (but I still love them). It's going to seem like a huge blast right off the bat, sorry about that. I'll update it as I go from now on. Maybe print it out in full color on your company's printer and go read it in the shitter, IDK.

So, a bit of backstory, everyone who knows me knows I talk about this thing all the time. I was trying to keep it on the DL online because I was trying to get invited to a "cool" event like born free or Brooklyn. I've since decided that I'm just a nobody and don't really deserve to be invited anywhere. Maybe sometime in the future. Also I am simply just not good at selling myself on social media, so here's where I'm at and I'll update this as I go.

Basically the whole project started like this, a titled basket 1940 EL motor.



By now I've accumulated basically all OEM (not year correct, though) external parts. I'm going to use S&S/Jims/Andrews internals. The motor will be mostly stock. I don't plan on making it anything other than clean, I want to leave all the "wear" marks in the parts that have accumulated over the last 75 years. Sort of like how I shined up this cam cover:



For the sake of the story, not much has happened with the motor, I've been too busy with other things to really dick with that. Also, for the sake of the story this is going to be a little out of order, but no one's probably reading any of this anyway.
I wanted to build a fork for this build, so here's the story of that:
Drew it in cad.







Got castings made from 3d printed wax off cad models. Material is 316L. This is not inexpensive, but I don't spend much money on things besides motorcycles, so it was within budget. All said and done I have into this what a nice condition early springer would cost.



Had to machine the castings. Fixturing these was often difficult and quite a learning experience for me.























 
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#2 ·
Re: 1940 SS Knuckle

Fucked this one up. It was late and I was tired and added .100 to .750 and got .760. Can see the hole is offset to the right:



Had to weld



Mill flat:



Bore:



Better:



More parts:


Made these from solid bar:



Polished/smoothed:



More polished parts. About 14 hours of polishing time for these two parts.









More polishing. Wound up spending about 100 hours polishing alone.



Made some axle nuts:



Some more things. I reworked that part that I mentioned earlier that needed more work. Got it very very nice. Part of getting it nice was the discovery of this technique for fine grit sanding. It's sort of like a cheap flap wheel that super soft. Basically just a worn down buffing wheel and some cloth backed sandpaper cut up. An internet guy named Benji showed me. What a sweet deal.



Came out nice:



This is the bottom that you will never see #selfie :



Next I polished these guys up:



 
#3 ·
Re: 1940 SS Knuckle

Came out nice:





I even tried something called grease-less compound, which is sort of a gritty paste you apply to a buffing wheel after applying glue, then it's supposed to make a soft, but gritty sanding wheel. Well that doesn't work, and it makes a huge fucking mess. More #selfie #dexter







It would work well for a few minutes, but it took longer to apply the paste than it did to wear it all off. Not worth the time.

I made an axle and stem bolt. First time doing manual threading on this lathe. Came out well, though I did find out there is a slight taper to the bed when I was trying to cut the bearing faces and the stem/tree interference face, but I was able to make it perfect (within a half thou) with some careful work.







Made a jig:



It's exciting to see hundreds of hours of work start to come together.

I didn't have a die big enough to put an 8" CLR radius bend on some 3/4 X .120 wall 316. I even called pro tools and the biggest die they can make is 7" CLR. The first person to quote this sentence and include your paypal address I'll send 5 dollars to because I don't think anyone actually reads it. They said they could outsource it, but it would be over 2500 dollars. Not worth it for 2 40 degree bends. Fortunately, my friend Zach gave me some oak boards. I drew a semi circle on them.



Missing a couple in process pictures, but then I clamped 2 pieces together, drilled and countersunk holes thru both, then cut out both pieces on the band saw. Then I took them apart and used a cove router to put a concave quarter circle on the curved edge:



Bolt both pieces together and now you have a forming die:



Soaked it in water for a bit so it would start on fire. Then filled the tube with sand and packed it tight, taped it off.

***If you try this, make sure your sand is baked dry. Even if it SEEMS dry, it's not and it can explode. Bake it for a few hours.***

Next I added some heat to the area I needed the bend to occur and bent that shit up. If I had to guess I'd say the wood die would last between 5 and 10 bends. More if you soak it longer and between each.



Checked the part to my 1:1 print, looks good a little off but:



Nope it's basically perfect:



Made a second one:



Right on. Then I sanded them with 120 grit. (Polish coming soon, but wanted to test fit-up)

Coming together!





Then finally got it welded together. Excuse all the fingerprints. I swear the polishing is nearly perfect.

It is full 316L SS. Uses friction dampers on the front of the lower link, which also has stroke limiters. The hardware is all custom made 17-4PH SS. The only part I didn't make was the spring (the acorn nut shown on the stem will be replaced with something I make)
 
#4 ·
Re: 1940 SS Knuckle

And here are the finished pics:











Once the fork was done it was time to move on to the frame:


Axle plates. These are almost totally hidden (more on that later) so I didn't sweat the polishing too hard.




Got some more wax castings done:



Then started the arduous task of polishing them. These pictures are "in progress pictures" I actually purchased and polished them before I had even started on the fork, and I learned a lot in that time. I re-polished them, but I don't have any good pictures.

This motor mount is desined in such a way that I don't need a squish pipe to run exhaust between the motor mount and the cam case:




Here's some more story time: the neck casting I had made was pretty cool lookin' But I tried my fuckin hardest to polish it and just couldn't get it to come out good.



Too many Nooks and crannies



So then I sacked up and sent it to Tony Brock @ Mirror Finish Polishing. I paid him 50% extra to expedite it. 500 fuckin' dollars. Well, after waiting nearly the amount of time he quoted me for a NON-expedited job, he sent it back looking like this:



He said that the expedited timeline starts when he deposits the check. OK. I then asked if I got a new neck cast with less small inside fillets if he would polish that one. He said sure. Well, I assumed that meant he would do it for free since I paid him so much to do basically nothing, so I had this one made:



I was getting ready to send it to him and asked him what his timeline would be and he said "several weeks and he'd only charge me based on actual hours" Fuck that. I was pissed and I'll never send him anything again. Next step was machining it



 
#5 ·
Re: 1940 SS Knuckle

Fuck you Tony I'm gonna do this shit myself











Then I got two super nice 1940 Half dollars and pressed them suckers into the neck:





More frame parts:





I know I make it seem like all this shit is easy and fast but I have been working on this project for a year. Working with Stainless, especially polished stainless is so much goddamn work. You have to think about when to polish, how to hold things, etc etc. I wish I documented everything, but here's one little part and all the steps it took. A whole day's worth of work most people would probably just think it's something I bought on ebay:
Start with some round stock:



Chuck it up in the lathe and make it shiny:



Cut it to shape, don't cut it off the bar yet though…



Get a new piece and start making something else:



Then make THAT shiny



Out of the lathe, into the mill:



Cope:



Then cut it off. Repeat 6 times:





Clamp so they're square:



Weld:

 
#6 ·
Re: 1940 SS Knuckle

Back into the mill. Face, then drill and tap:





Step back and admire the work you did that no one will ever care about:



Made some more little dodads for the frame.





If anyone is wondering how I do this with no CNC, you make lots of little cuts to a print, then file and sand it smooth. Lots of time, again.





Here is another part, the slug for the joint where the axle plates meet the frame



There are lots and lots and lots of other parts that I had to make just for the frame, but I don't have pictures of them all.

I did buy this tubing roller from harbor freight for some parts of the frame:



That wood die trick I used earlier held up in my hydraulic bender! So that was nice. I added some plates to the side for rigidity.



The chainstay portion of the frame is in tension, so I wanted a little extra weld there. That's what these holes were for





 
#7 ·
Re: 1940 SS Knuckle

I'm going to gloss over about 4 week's worth of work of cutting and bending and shaping and sanding and just jump straight to some finished pictures. There are hundreds of hours in this frame:



















@soulofire_ took these:





I also designed some hubs:





And made a lot of other pieces:







 
#8 ·
Re: 1940 SS Knuckle

I bought some Borrani rims direct from Italy and painted them at my friend's shop. Then I sent them to Buchanan's to be laced up. They did a good job.











Ok, so now I'll jump to some pictures from when the frame wasn't complete, but I wanted to check the fitment of some components. This whole build hinges around the concept of having the rear sprocket and brake outbuard of the frame in the rear. The sprocket and rotor spacing is standard shovelhead, the frame rails at the back are only 4.5" on center. Everything fits as it should.





The rear drive. Sprocet is similar. Right now I have components for a keyed shaft but I may commission a splined shaft. (I can cut the keys but I can't cut the spline)



Neck detail



Here's some detail of the front wheel. Assymetric hub, half radial laced, half 4 cross.



That takes us to about the present. I've been working on some motor and trans mount parts the last couple days:





Some gussets will go under here



Pretty good fitup:





I got the motor mount welded in which was the last thing I had to do in the jig so I was able to pull it out tonight. I've gotta knock that lower neck cup out of there unfortunately. I rushed it in a few weeks ago and the stop tab attached to the cup is twisted. I can't get a good piece of it with a punch so I think I'm going to have to weld a plat across the bottom of it and wail it out.





 
#9 ·
Re: 1940 SS Knuckle

Made some nuts for the rear axle. I intend on having both sides removable.

When I made my axle, I put a left hand thread female 3/8-24 thread and a male 3/4-16 thread on either end. The purpose of the internal thread is to lock the axle nut in place without using lock tabs, etc. I wanted to use safety wire. There are a million ways to do this, I just chose a method that I thought was interesting.

The axle looks like this. The nut threads on and then a left hand screw and washer go in to prevent the nut from backing out. Since it's left hand thread, they have to spin opposite directions to unscrew.



Here's the nut and locking screw. Once installed and torqued, I'll add some safety wire between the two items to prevent it from loosening.



Here's the drawing for the nut.



And here are the steps to make it. It took 5 hours to make both. I figured if I typed this out, people would get some ideas on how to make their own stuff, or just how involved making even simple parts is. I chose to make it out of 1144 steel (called stressproof) because it has a good combination of hardness and toughness, machines well, is hardenable (if I decide to) and most importantly, I had some 1.5" stock laying around.

Face your shaft. Technically the "right" thing to do is to mill it flat in the rotary table, because then you know it would be true to the rotary table, but for this it doesn't really matter and the lathe is faster. I took off about .010, just enough to make it smooth.



Put the part in an indexable rotary table on the mill. Mill the decorative relief slots in. I cut each slot in 4 steps (.25,.50,.75,.825 depth), on the final step I cut in an additional .010 so the whole cut was uniform.



Next I milled the hex into the sides. I roughed each side in to +.010, then measured and came back through and cut to final dimension. I'll note that the final cut had to be actually .012 depth. Are you reading this? I love boobies. This could be due to a variety of things, tool wear, DRO error, slop in the rotary table, etc. I think often times people don't realize how much measuring and adjusting you need to constantly do on old machine tools. Also to note I used both climb milling and conventional milling.

Here's a little image to explain that:



Generally for steel you want to use conventional milling (try to use climb milling for aluminum always). If it's a super accurate part, you'll want to use the same type of milling for all sides, but I was getting good surface finish in both directions, so I just locked the Z and Y dims and went back and forth, rotating the part 60 degrees each time.



Next I drilled a hole. If you wanted it to be a perfect cut (which this isn't) you should A) use a good drill (which this wasn't, but I didn't use the endmill in the picture) B) drill a size close (like 1/32 under), then drill with the correct size. If you wanted it REALLY accurate, like for a bearing fit, you would use either a ream or a boring head. This is just for a threaded hole, so a drill is fine.



Next I milled a relief for the locking bolt's washer to rest in. This was cut with an endmill at full depths in 3 diameter changes (.150,.185,.200). This was a lot of continuous cranking. I think it goes about 5 degrees per handle revolution, so that's 360/5 * 3 = 216 cranks.



After that I machined in the "castle". Milling was done at full depth. I haven't been mentioning any feeds or speeds, but tool speed was about 800rpm and feed was whatever "felt right" at the knob, which was probably about 2 IPM.



Since I wanted to add those decorative little holes, now was the time to do that, because trying to add them in later on an angled surface would be next to impossible without a micro end mill (the hole is 3/32). Even on a flat surface it's easy to get drill deflection with a tiny little drill, so that's why i'm making center drill holes here. Also, my 3/32 drill had a tiny wobble to it, so this makes sure it tracks straight.



Now drill the hole with the little drill. I'm spinning about 1800 rpm and feeding VERY slowly. Drill depth was .153 and it took about 90 seconds to drill to that depth.



Next make some chamfers. More cranking. The top three are easy; you just set the tool and crank the part around, the lower three are a bit harder because you need to stay between the "castle ramparts".

Not my drawing, but I think we could all benefit from more shitty castle drawings:


A note on chamfering. It's hard to get the correct depth when you're doing an angled cut like this because the depth of cut is contingent on the cut diameter. That's why I added the Vs on the print in the upper right view.



Then I put the part in a lathe and first cut a relief in the bottom to act as a built in washer. It's .03 X .03. Can be seen on the print. This help prevents the nut from putting a visible scratch on the part it tightens against. Then I cut the part off completely.



Next, I manually tapped the hole. I do all my tapping in the bridegport because I am sure my tap is going in straight. After spending 2 hours making the part it would be really annoying to have the hole tapped crooked. I do this by just putting a piece of .25 rod that I sharpened (with a hand sander while spinning it on a drill press, I might add) into the collet and then moving it down every half turn until I'm about 4 full threads into the part. Sometimes more, sometimes less. One of these days I'm going to make a spring loaded deal, but no time right now. Add it to the list I guess.



The last step, which I forgot to take a picture of, was putting the nut in the vice and slowly drilling the safety wire holes in the "ramparts".

So here's the finished nut. Came out pretty nice. The chuck put some minor nicks in one of the nuts when I was tapping it. I will tumble them a bit, then have them electroless nickle plated with a few other parts. I chose ENP because the other parts have fits associated with them and ENP goes on very thinly and uniformly.



Hope you learned something about castles!
 
#10 ·
Re: 1940 SS Knuckle

nuklhd said:
whats the issue with the motor mounts in the frame?
If the left rear bolt hole is set to (0,0) with positive X being toward the cam cover and positive Y being towards the front

Cad Model:
LF: (0,10.563) RF: (3.250,10.563)
LR: (0,0) RR: (3.5,0)

My actual cases measure:
LF: (0.134,10.531) RF: (3.387,10.531)
LR: (0,0) RR: (3.5,0)

So I need to rework the rear holes on the frame to get everything to line up.

So as mentioned in my last post, I had a left hand internal thread on my axle. I called and searched high and low for a left hand 3/8-24 socket head screw. No dice. Lots of places said they "had" them, but they were special order and I'd need to purchase 200.

I thought about it for a bit, scrounged around the shop and found a couple of these. A stainless 1/2-13X1 SHCS. A quick measure let me know that the root depth was greater than .375 so I was in business.



Chucked it up in the lathe:



Machined it down to .75 thread length:



Next, I machined the threads off:



And turned it to a diameter of .375



Next, added a chamfer with the edge of the threading tool (this isn't the appropriate way to do this)



Then I started to thread it.



Then I forgot to take pictures, but I drilled 6 safety wire holes in the newly threaded bolt, then put it back in the lathe and reshaped the head and polished it. Sorry about the slow step by step, then just a massive jump to: "... and then I was done!"



I was thinking to myself, wow, I'm going to make tons of my own fasteners like this, but I can't, because in order to cut RH threads the carriage needs to move TOWARD the chuck and I could never disengage the half nut in time and i'm sure I'd wind up crashing into the chuck. I'd have to thread it with a die or something.

So my plan for fork stops has been to use a neck cup with a stopper built in. I had pressed one into the frame to get it out of the jig for a test fit, but when I did that, it didn't go in exactly straight. (It was in the bore straight, but it was twisted, so the "stopping" locations would be off. Not only was it difficult to verify the straightness while starting the press, but the bolt I was using to draw the cup in twisted the cup as well.

I wasn't about to let that happen again.

The first thing I did was get the old cup out. Couldn't get a punch on it from the inside and I didn't want to risk damaging the neck, so I just sacrificed it:



Next I made this paddle looking thing.



That totally looks like a face...



Then I turned some inserts that fit nicely in the ID of the upper and lower cups



When the cup is placed over the spacer (and the bolt is there) the cup is located perfectly in line with the tube extension.



Then I had a friend hold the frame steady, another tightened up the bolt while I verified that the extension handle was (for all intents and purposes) inline with the backbone. It worked fuckin' perfect.



Then I drilled the neck out and pressed a pin in to ensure that it can never rotate.

 
#11 ·
Re: 1940 SS Knuckle

In this episode of make-a-nut, we're going to make another nut! This time for the stem.

First, make a drawing. The prime time to do this is when your GF wants you to do something.



Start with the same piece of 1144 from last time. Drill some pilot marks.



Then drill them deeper. Remember to go slow, you're drilling these little holes now so that in case you snap the bit off in there, you won't try and angrily flip over the bridgeport. It sure seems like a lot of material.



Then clean off the scraps. Looks pretty goood.



Next, drill a hole. Make sure you drill it deep enough to tap it before you cut it off. Maybe go a little extra, because maybe those full threads on the tap aren't ass full as you think and MAYBE later when the nut is cut off you're going to have to find a way to hold it without fucking it all up.



Next, drill a bigger hole. Just make sure it's about .040 smaller than the size you're going to need. Don't have a giant drill bit? Well maybe your next door neighbor used to be a diesel mechanic. Go ask him. No? Then you remember you used to beat your son with a sock full of drill bits. Yep, there's one in there, and it's perfect. Clean off the blood and go to town. You're probably going to want to drill this under 200rpm.



Break out the boring bar and machine the ID to the print. At this point, don't take the time to realize that the drill size for a 1-24 tap is .955 and not .965. Also, be sure to accidentally make the hole an extra .010 big because you didn't zero your calipers out properly.



Next we are going to put a little step in there to be used later.



Now use a 1/2 endmill and make the first feature.



And now use the same tool to rough in the flats. At this point your hands will start to hurt and you'll begin getting hungry. Consider giving up on motorcycles altogether and becoming a chef, however, once you have the last cut done, feel glad that your drill holes you added for reliefs all appear straight and correctly placed.



Grab a smaller endmill and machine to size.



Grab a socket and cross your fingers that this will work, because you've got like 4 hours invested in this damn thing and you've never made a 12 point nut before. Hey, it fits!


Next, add some chamfers because you're cool. Chamfers are cool, too.



Then add a bunch of crap to the bottom that you're theoretically going to use as a nut locking safety device.



Now it's time to tap. First, worry that the tap is going in a little too easy. Next, curse yourself for not making the whole deep enough to get full thread engagement. Finish tapping and look at the threads. Hmm, they don't look right. Go get your calipers. Go get a stock stem nut. Realize there is a .020 difference in thread minor diameters. Think long and hard again about giving up on motorcycles forever. Go on the internet. Check several sources about correct thread drill diameter. Curse. Look at a couple butts on the web. Start the whole project again. This time it only takes about 2.5 hours to get back to this stage. This time make sure you use an inside mic on the thread ID hole. This time drill the hole deep enough.

That looks pretty good, EASY!



Now VERY SLOWLY drill a .083 hole in each little tower.



Now tap those tiny little holes to 4-40 for a set screw. Consider setting up a noose on the overhead crane in the event you snap the tap off. Break your chip every 1/6 of a turn (vs the usual 1/2 turn). Top secret message: The hen is in the nest. Sweat runs in your eyes as you tap your part at a snails pace. The tap does not break and your fancy new nut is almost complete.



Spend some undocumented time making a filler piece with your initials on it out of 316SS



Question whether or not you're a narcissist.



You decide you're not, so make this rippled finisher part instead. Realize that you've spent 13 hours making a nut for your motorcycle that most people will probably thing you bought. You're tired and hungry. Go to the supermarket and buy a bag of spicy nacho kale chips and soy egg nog because you deliriously think it will be a good combo, and because you're a vegan and clearly must have judgement issues anyway. Drink almost the entire 'nog on the way home from the shop and go to bed without taking a shower. That's how you make a nut!

 
#15 ·
Re: 1940 SS Knuckle

I'd like to be invited too even if i know that that won't ever happen. I think you should build your bike and go to born free. BeCause i think if your design skills are as unreal as your fab skills you will completly pulverize them.
Having ones bike next to yours would be the worst place on the whole meet cause it would make it look like shit what ever they have done to their bikes.
 
#18 ·
Re: 1940 SS Knuckle

I'd like to be invited too even if i know that that won't ever happen. I think you should build your bike and go to born free. BeCause i think if your design skills are as unreal as your fab skills you will completly pulverize them.
Having ones bike next to yours would be the worst place on the whole meet cause it would make it look like shit what ever they have done to their bikes.
I'm thinking that I will try to do that, but it's looking like I won't be able to get it done for next year's event. I work on it nearly every day and I'm not even a full roller and it's been a year. :O
 
#17 ·
Re: 1940 SS Knuckle

You sir an artist of the lathe and miller. Can't wait to see the knuck finished. I have no doubt the detail will win some awards alone. Lovely to see somebody so infused about the detail. Question is do you actually do any work in work? or just machine sick parts?!
 
#20 ·
Re: 1940 SS Knuckle

You sir an artist of the lathe and miller. Can't wait to see the knuck finished. I have no doubt the detail will win some awards alone. Lovely to see somebody so infused about the detail. Question is do you actually do any work in work? or just machine sick parts?!
I'm a mechanical engineer, so 8-5 M-F I do that, then usually work in the shop from 5-1, almost every day, except on the weekends, when it's shop time from 8am-1am.

I don't have any formal machine training, I just taught myself by reading and trying.

What I also don't have is much of a life.

Here are some other things in my garage:

53 panshovel that I'm throwing together with parts from around the shop, all I've made for it thus far is bars:




This 99 sporty chop. The coolest part about this bike is the 1 gallon reserve fuel tank under the oil tank. It has an electric fuel pump on a timed relay so once you hit reserve on the main tank, it pumps all the gas through a check valve and refills the main tank. There are a lot of other one off parts on it like the fork shrouds, risers, top triple tree, pipes, controls, etc. Just rode this one from Buffalo, NY to San Diego.















This "59" pan chop is my daily rider and dangerous as hell, a few custom tidbits here and there, like a tail light made from an old poweline insulator





This turbo 78 shovelhead that I posted here before:













This 75 CB550 that was my first motorcycle:





Then there are a few other misc ones like another sporty I made for my GF, a 93 fatboy and a 16 heritage.
 
#19 ·
Re: 1940 SS Knuckle

I'm just here with my files and MIG welder...

You know you're fucked when not only can you not figure out how Newman made this shit, but you don't even know what the name of the fucking machine is that he did it on is.
 
#25 ·
Re: 1940 SS Knuckle

You know you're fucked when not only can you not figure out how Newman made this shit, but you don't even know what the name of the fucking machine is that he did it on is.
The machining I get and you did a hell of a job documenting it. I thought I was the only nut job that liked to document stuff like that.

The casting process is what amazes me, I get it, but never did it, so sometimes it's hard to fully understand.

Nice work all around.
 
#21 ·
Re: 1940 SS Knuckle

...
great skills and eye.

-the frame is really nice specially the curved part in the tail side tubes and the "shadows" that the welding let.

-The potential to know how to use these cad programs or have some one to made the draws is a HUGE advantage.

-Find a shop that accept these small (quantity) works.

-Find the right materials. Here, there are no availability of anything like that.

-Have the right tools.

-Incredible that you still have a gal...between those hours that you posted seems there is no time for her; and we all know that there s no gal that do not demand time.

-I do not have nothing of that so I am building a daily driver like in the past.
 
#23 ·
Re: 1940 SS Knuckle

lovely selection of bikes man i'm very jealous! all those working hours does you alright it seems, got a small fortune there. Knuckle for me next, then I want a dodger charger I can tinker with. Also just bought an R100/7 BWM scrambler!
 
#24 ·
Re: 1940 SS Knuckle

I hope Guy from GKM is watching this unfold...

Beautiful craftsmanship, and all in stainless too. This is insane.

I'd post more compliments but I need to get into the garden to tend the big bonfire I just made of all my tools and everything I ever made, after reading through this.
 
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