Finishing the steering stem

It was way back in July that I turned the blanks for various length steering stems.  The various lengths allow me to adjust the amount of dive that happens under braking.

Here's where we left these parts:

Now these parts will be brought to the 4 axis mill and have the pivot holes and clamping faces machined.  then i'll switch to another setup and trim and chamfer the ends.

The first step is holding the parts in a 3J collet on one end and with a dead center in the other to ensure the part axis is coincident with the mill 4th axis.  That means that the zeroth step is to align the dead center to the 4th axis.  I machined a round adapter that helps greatly in this process:

I then remove this mandrel, reinstall the dead center quill and then clamp a part:

To check the alignment I held a .0001" indicator in the mill spindle and rotated the 4th axis.  the part was within .0003 TIR, which is an excellent runout for a 2nd operation clamping.

Now that the part is properly clamped and in alignment I can machine the features that mount the upper and lower control arms.  the machining is 4 pocketing routines and 2 reamed hole routines ending with the almost complete part:

Repeat this a few times with appropriate modifications for the various lengths and i have a bunch of useable parts:

Now there is a simple cleanup operation to do on each side to round and smooth the ends.  The part is held in the 4th axis in a 3J collet with the end just sticking out.

I profile the end, then chamfer it and repeat for both ends top and bottom:

The finished parts are pretty sweet lookin:

 Especially when assembled in the spider:

That's one more part to cross of the to-do list.  The front end is starting to take shape, i'm only missing the control arms which are next on the list of complex parts to do.  I may try to squeeze in a few simple parts before that, let's see what the next week or 2 bring.



That's all for now.

Front end assembly

Now that the spider machining is done I can bolt the legs on and hope the axle holes line up!

As expected both legs fit properly and the axle is a nice smooth sliding fit through both legs.  The assembly looks pretty cool, especially compared to the simple previous design.

Once I finalize the rim/brake rotor combination the radial caliper mounting holes can be machined in their proper places.  The calipers are the dual Brembo radial mount big pad CNC versions (with the radial caliper too) which will be total overkill for such a light bike, but we like overkill on the brakes, which should be the bike's strongest point.  Why Brembo?  They are the best.  Period. I got them from Fred Renz at Yoyodyne who has a huge selection of high end parts at good prices.  Rims, brakes, bodywork, slipper clutches, etc.  No waiting for drop shipping from the manufacturer, he's got it all in stock.

The rotors are Brake Tech Iron Rotors that use a different method than the usual round button to transmit the braking torque from the rotor blade to the carrier.  When we were running the Ducati/Rotax single which only had one front disc the buttons on various name brand rotors were constantly being galled and requiring replacement. Once I switched to the Brake Tech rotors all wear was eliminated.

In this photo you can see the flat surfaces that transfer the load.  The buttons are merely for axial retention.  All the parts are finished to a high level of detail with a nice even anodized finish.  The rotors are even cryo treated!

They are definitely a manufacturer I recommend when replacing brake rotors.  If you have deeper pockets they also make a ceramic matrix composite rotor that works great on the street.  It is super light and great for a track day bike but unfortunately not allowed by most race organizations.


Next post will be the 4th axis work on the steering stem, hopefully in a day or 2.

T-shirt design is in!!

After starting a donations post for the blog that you can see here I realized that we didn't have any t-shirts available and didn't think people would want a plain fruit of the loom.

My solution was easy, call Sacha Halenda of Form Five and have him whip up something superb.  Sacha is responsible for creating both the Cosentino Engineering logo and the 'Cosomoto' name and gear/wing logo, among many others.  He has a great talent for creating an identity that is new and unique yet still allow that graphic to evoke the familiar emotions that consumers need to relate to a new entity.

The first shirt design focuses on the V4 engine design and features a large wireframe drawing of the motor on the back side and the text 'crew' on the front with some stylish accents.  Although we have not finalized which vendor will print the shirts we will be using shirts that are 100% Made in the USA.

Front:

 

Back:

 

The bonus of having one of these shirts is that if you are wearing one at a race event we're at you are welcome to come in our pits, pull up a chair and make yourself at home.  Without one of these tees you can come in but you'd better not pull up a chair.....  Also, you'd better like Mexican food as we have a rule about not eating anything else for dinner during an event.  We have a detailed map of every Mexican restaurant (or taco truck in the case of the Bonneville Salt Flats) within 50 miles of every US racetrack so are never caught unprepared.  Cue whatever jokes you can think of about more gas to help the bike go but it works for us!

As we continue with the project and as interest allows I'll have Sacha make more shirt designs relevant to our current state of progress.


If you like the shirts please go over to the donations page and make a contribution.  Don't forget to let me know what size to send.


Chris

Machining the front spider

With momentum still rolling along I started on machining the center spider for the front suspension.  This is a multifunctional part that holds the upright legs, defines the steering axis, and connects to the control arms and steering links.

We'll move along the well-rehearsed path of machine fixture, mount part, machine part, reorient, machine part again.  The fixture has several dowel pins to register the part in correct alignment before it is clamped down onto the swivel pads that provide proper spacing and restraint.

Here's the part clamped in place:

I then machine the part in 3 steps in this arrangement: the top and 2 sides.

These first 3 operations are all done with simple end mills and drills.  When I index the fixture 90 degrees to machine the steering stem bearing seats we will need to use some extended reach tooling.

Here's the 2 flute insert mill used for roughing, the boring bar used for finishing, and the custom long reach retaining ring groove tool made from a slim carbide slitting saw and some precision ground 5/8" diameter shafting.

Here's the finished bore:

And some finished parts:

There are 2 different versions of the part, a tall one that provides much less front end brake dive than telescopic forks and short one that provides closer behavior to teles.

Once I do some deburring and test fitting I'll post some images of the front upright assembly.  It will look really cool.

That's all for now.

Na, shafts are boring

I know the last post said the next one would be doing the oil pump shafts but I changed my mind and decided to do something a bit more complicated and settled on machining the steering arm castings.  They've been lying around a while and are definitely aged enough.

This part is roughly equivalent to the upper triple clamp on a conventional motorcycle.  Unlike an upper triple clamp this part is not subject to suspension loads, only steering forces.  The dual drag link configuration is designed to transmit maximum feel from the front upright-wheel assembly to the rider's hands.

The raw castings are shown here with a fresh fixture sub-plate and the material stock for the mounting fixture:

I manually machined the 2 fixture blocks that would mount onto the fixture sub-plate and the part would be mounted on.

 

The completed fixture assembly is shown installed on the trunnion table.

It is a pretty simple fixture but does require locating pads and holes to be premachined on the castings.  This is a simple enough operation that it can be done on the manual mill too:

Now the part bolts directly to the fixture and has one small preload bolt to eliminate chatter when machining the center bearing features.

In the 0 and 180 degree orientation we machine the center pivot bearing pockets, clip on mounts, rotary steering damper mount, brake reservoir mount, and logo.  There's not much material removal so it only takes a few minutes.

I then index the fixture plate 90 degrees and machine the steering drag link bearing mount holes on each side of the part.  This is another quick operation and proceeds with no problems:

That completes the part.

Now reload and rerun a few times and I have 4 machined castings ready to use:

That's all for now.  I think the next part will be the front spider which will allow me to test assemble the upright assembly.

Helical Clutch Actuator

This post will document the fabrication of the mechanism that converts the linear pull of the clutch cable to the motion required to release the clutch.

As this is one of the user interface elements of the bike some attention needs to be paid to the forces and leverages involved to be sure the clutch pull is not too stiff yet firm enough to allow the rider to modulate it a bit.  This was pretty simple and I found a reduction ration of about 5:1, meaning that .5" of clutch cable pull should equate to .1" of movement of the clutch pressure plate.

Now that the desired leverage ratio was determined I needed to design a mechanism that fit the available physical space.  As the clutch is protruding slightly past the frame on the right side of the bike I wanted to keep a low profile so that the actuator was not the first victim of a lowside crash.  Several of the current Supersport bikes use a rack and pinion style actuator with the clutch cable tied to the pinion and the rack having a thrust bearing to mate with the pressure plate.  This style is nice but is long.  Being long does not matter for the I4 engine style as the outer cylinder is wider than the clutch/trans area but the extra length would not package well in my V4 configuration.  I thought about using the self contained helical actuator from a SV650 as done with the custom slipper clutch for the Rotax single:

This design worked well but was a little long and visually messy as there were several external components that were not that pretty.  It also was a bit difficult to properly seal and since oil on the rider's left boot is not a good thing I set this idea aside.

Knowing that I'd like to have about .15" of pressure plate travel (a bit extra is always nice to allow tuning of the slipper effect) I set about designing a thin actuator that provided the needed travels.  I ended up with a very slim design that used roller bearings for all motions involved to minimize friction and maximize feel.  One important design point was that I wanted to use a readily available clutch cable so spares were easily sourced and inexpensive.  Since there are some Kawasaki OEM parts in the engine it ade sense to design around a Kawasaki ZX6R cable which is what I did.

The aluminum housing parts are already made so the helical actuator part is the only one left.

In this cross section through the clutch shaft you can see the details.  the release balls are not visible but there are 3 of them in 3 matching helical grooves.  As the clutch cable (shown in the first CAD rendering above) pulls on the grey part it pivots around the radial bearing while the release balls ride up in their grooves, thereby moving the grey helical actuator away from the engine.  The gold connector rod then pulls the clutch pressure plate up with a thrust bearing sandwiched in between to allow rotation of the clutch.

You can see them and the helical grooves in both parts in the following image:

 The design met its 2 primary goals well: a. slim design that needs less than .6"of thickness from the outside of the clutch pressure plate, and b. Smooth motion through the use of roller bearings on all motion axes.  Now its time to machine.

So here we start with a couple of pieces of stock and a chunk of aluminum for the 2nd operation fixture:

Stock clamped for the first operation:

And the first operation complete:

The radial grooves were done using a 1/4" diameter end mill with a ball end and plunging in the Z direction while doing a G3 arc move.  I used a .250" end mill but used 6mm (.236") balls to have a little clearance so that they no not bind due to the unavoidable manufacturing tolerances.

Now I made a fixture plate that this part could bolt to and ran the 2nd operation program:

I ran a 2nd part to have a spare.  After welding the radial bearing boss on and a  little manual machining for the cable end pocket and retaining pin and the part was finished.

You can see the rotary/linear action in this short video:

That's one more subsystem complete, next will be some internal shafting for the oil pump.  these are simple parts so will be done manually on my Hardinge lathe and should be done in a day or 2.

Let's get things moving!

Here's you chance to help us out!  I've been moving along with the project as I can but progress can be much faster with your contribution.  I want to try to get the engine running by the end of the January and we can get there but need your help.  I've set up a PayPal address that will accept donations of any amount.  You can click the button here or the donations button on the right side of the blog under the followers.

                                      

What I need is $25,000 to get the first 2 engines up and running.  The money will be spent on the following items:

-3 of more sets of crankcase castings  $3000

-finishing of 3 crankshafts: $4000

-primary drive gear grinding for 3 pieces: $1200

-Nikasil cylinder plating for 4 castings: $2200

-ECU/support electronics: $10,000

-dyno engine fixture: $2000


There's a little cushion in there for potential bumps in the road.  These expenses are for outside vendor work and components.  If I could I'd make this stuff in-house but in these specific areas it is best to go to the acknowledged experts in the field to get the work done right.

Donations of any amount are accepted.  For a $50 donation you will receive a t-shirt and sticker.  $250 gets your name on the fairing in 24 point type.  Donations of $500 will earn an engraved name on the cases of the first and second running engine.  Imagine how cool it will be to show up at a racetrack and be able to point out your name engraved on a racebike engine!  I have not though about perks for gifts over $500 but feel free to test my imagination!

Regardless of how much comes in through these donations I am still moving forward as fast as possible with the project.  I am currently throwing everything I have at it and will continue to do so.

Thanks for reading and following the project, your comments and readership help me to continue pushing for completion.

Another operation done....

To keep the streak going I finished the clutch cap on the lathe today.  The first milling operation went smoothly but this lathe operation had a slight bump or two in my way.  I initially programmed the part using conventional tooling but the recessed pocket really needed some more specialized face turning cutting inserts.  The problem was minor and did not cause any undue headaches but the program needed to be redone.

The first step was to cut some profiled soft jaws to hold the part:

The small burrs you see are away from the profile and will not cause any clamping problems.


Unfortunately I was on such a roll I machined all 3 parts without taking any pictures of the process!  Here's the final 3 pieces looking really good:

The clutch side is nearly complete and looking great.  I'll try to get to the oil fill and crank end plugs today then next week I have to do a bunch of contract machining so will likely be too busy to make bike parts.  Damn.  I will try to get to something done to keep the streak going.

Gettin on a roll

Ahh, peace and quiet to make bike parts.  As close to nirvana as I can get these days.

Today was a low hanging fruit, the clutch cable actuator cover.  This is a cute little piece with the gear to wing logo and 2 versions of the name, "Cosomoto' and 'Cosentino'.  I'm partial to Cosentino for obvious reasons but Cosomoto is just to close to Quasimodo.  Either one, I'm covered!

Parts blanks and layout sheets:

Simple fixture plate:

Op 1 (top) and 2 (bottom):

2 pairs:

With the top surface finished out:

Next I'm going to finish up the clutch cap and machine the helical actuator and that will then let me assemble and test the clutch actuation mechanism.

It's great to see the visible progress.  A running engine can't be far away.