RZ350 re-frame... classic 2-stroke gets modern upgrade

[Frame Maker]

SolidWorks is the beez neez, good for you! I have just downloaded the latest version but have not had time to get into it. I have some experience with SW 2005 so it has been quite a while. Since that time I've used Creo (used to be Solid Designer) and before that ME30. We have recently transitioned to Siemens NX which is incredibly difficult for me to understand.

Dan

I'm a bit envious that you're getting exposure to the top three CAD programs. A few years ago I was a contractor at GoPro. At the time we were working on development of Hero5 camera. There were some new guys that came over from Apple and were NX users. A few engineers were using Creo, and few of us using Solidworks. It was like the wild wild west with anything goes. I was the lucky guy that got to wrangle everyone's sub-assemblies into one master assembly. That was fun trying to import/export between the three CAD programs. It certainly kept me on my toes for sure.

At home I have SW 2006 that I use for the moto projects. There are a few modern features I wish I had access to but (as you can see) I'm doing okay with it as-is.

While we're taking about CAD, I'll put out a shameless plug and mention that I'm currently out of work and looking for employment. My background is in consumer product development with the past 6 years working more specifically on light EVs. It doesn't show in my motorcycle work, but my expertise is in injection molded plastic part design.

Again, nice chatting with you.:thumbup

 

[bergmen]

Injection molded plastic is in my wheel house also. My engineering definition is basically the non-analyzer infrastructure engineering design. This is on high end gas phase or liquid phase mass spectrometers and includes everything not in the vacuum system. Structure, card cages, external enclosure, operator interface, serviceability, manufacturability, shock, vibration, all other QA testing, etc. etc.

Creo was easiest and best at this. It is no longer supported so we have to transition to NX (corporate decision).

It is a tough row to hoe but I have to make it work...

Dan

 

[DefyInertia]

I’m blown away. So rad.

 

[Frame Maker]

Part 8: real time progress

A few weeks ago my big blue box came home from the hospital. Diagnosis was a bad torch. Although not common, I guess they can go bad after 25+ years of use. While the machine was apart, they also replaced the rectifier bridge, the high frequency points and few other routine maintenance parts. It seams to be working well again. Hopefully good for another 25 years of use.:thumbup

20210115_133052 by andbike, on Flickr

So on with the sub-frame reconstruction. At the same time I'll be changing the tank and seat to one generation newer. I just like the styling a little better on the '03-'05 R6 tank. The tank mounts are identical to the earlier style tank, but the seat mounting is different. This means that I can't simply copy the original sub-frame.


'03-'05 R6 tank and seat:

20210123_143333 by andbike, on Flickr

To aid in the construction I'll start by building a fixture off of the original sub-frame so that I can easily replicate the frame mounting positions and the tank mount.

Original sub-frame and construction of the fixture:

20210123_143049 by andbike, on Flickr

20210123_143130 by andbike, on Flickr

The fixture is now ready with locating features for the frame mounts and rear tank mount. I can begin building the new sub-frame.

20210129_161421 by andbike, on Flickr

20210130_150049 by andbike, on Flickr

20210130_150058 by andbike, on Flickr



First test fit on the bike looks good!

20210130_162455 by andbike, on Flickr


And very rough mock-up of seat position.

20210130_162839 by andbike, on Flickr


I have a fiberglass tail that I will likely be using. Or I should say that I plan to use a modified version of. The tail looks surprisingly similar to one from a Honda RS125, although when compared side by side the Honda seat is much smaller. This tail is from Airtech and is for a KTM cup bike, although it also looks exactly the same as the tails offered by BeOn with their 450GP chassis kits. Anyway, I like the basic shape. It will need to have the seat area cut open to fit around the R6 seat. At some point I will re-sculpt the overall shape a bit just so it isn't an exact copy, and also to so that is looks more compatible with the R6 tank styling.


Here's a quick mock up with the tail in place. I really like how this is going to look!arty

20210130_163455 by andbike, on Flickr

20210130_163521 by andbike, on Flickr

Next is to add seat supports and mounting details. Since the '03 seat is different than the '02 seat, this will be back to some trial and error. There will be two supports. One across the front and one across the rear of the seat. Once I'm confident with the position (height) then I add the securing features.

20210201_122101 by andbike, on Flickr

20210201_122117 by andbike, on Flickr

20210201_123106 by andbike, on Flickr


I can now sit on the bike and the seat position feel really good. For some reason all of my sport/road race bikes seam to end up with tall seating positions. When measured at the middle of the seat, the height is about 33". If I really wanted to I could bring the seat down by 1/2". I could also tip the back of the seat down a bit, but it feels really good when sitting on the bike with feet on the pegs. Lowering it at this point would be a significant amount of work for minimal gain... and I'm okay with this position for now.

20210201_122209 by andbike, on Flickr


The seat height is primarily dictated by alignment to the tank and the rear of the tank is located just above the upper shock mount. So without a major re-design of the rear suspension there isn't much room for bring the tank and seat much lower. When I build the second batch of frames (with the above discussed re-design) I'll take another look at the seat height issue. Reviewing spec sheets I see a lot of sport bikes with 30" to 32" seat heights. My AK-1 race bikes have the same seat position at 33" and never had any issues and they have won a lot of races. What do you folks think... is 33" too high for a sport bike?:dunno

Stay tuned...

 

[budman]

Love the tail piece mock up. Sexy. :cool

 

[budman]

Oh ... for this OG... the higher the seat the better. :laughing

 

[DannoXYZ]

awesome work Julian!

What tubing material are you using?

 

[bobl]

Oh ... for this OG... the higher the seat the better. :laughing

Amazing work. For this busted up and shrinking old fart, I need lower seats.:afm199:laughing

 

[Frame Maker]

awesome work Julian!

Amazing work. For this busted up and shrinking old fart, I need lower seats.:afm199:laughing

Thanks guys. Much appreciated!:thumbup

What tubing material are you using?

This is a great question, so hoping my answer isn't too engineery...

The short answer is mild steel CREW (cold rolled electric welded) tubing. This is the most common and least expensive type of steel tubing available.

For the long answer, a lot of people have asked me why I don't use higher grade materials such as 4130 (cromoly) or DOM (mild steel "drawn over mandrel") both of which are stronger than mild CREW tubing.

Here is where I usually loose people in the discussion... the first thing to understand is the difference between "strength" (yield strength) and "elasticity" (modulus of elasticity) and why they are different properties, yet still important. The best explanation for each of these properties is to describe them in terms of motorcycles. Elasticity is what we experience when we feel the frame flex. The metal moves a small amount, then moves back to its original location. Strength is what is experienced when a motorcycle is crashed and the frame gets bent. The material has been moved a large distance and doesn't move back. It has "yielded".

So with those two conditions in mind, I will say that both mild steel and 4130 cromoly steel are both nearly identical in terms of their modulas of elasticity. In other words, you would feel the same amount of frame flex riding a motorcycle made from cromoly as you would on a motorcycle made from mild steel. Both materials will flex nearly the same amount under small forces. The difference is when you crash, mild steel will bend (and not bend back) sooner than with the higher grades of steel.

Because of this, I use mild steel. It is cheaper, easier to source, and much easier to fabricate (because of the lower strength). The well known moto author Kevin Cameron once described it something like this... "Cromoly is only an advantage if you can crash hard enough to bend mild steel, but not hard enough to bend cromoly".:ride

Thanks for the question:thumbup

 

[GPzPop]

is there a weight advantage to cro-mo over mild steel tubing?

what about your "sourced" cnc parts from overseas ? is there a choice in the alloys used? how is the quality control vs price point ratio?

Thanks guys. Much appreciated!:thumbup




This is a great question, so hoping my answer isn't too engineery...

The short answer is mild steel CREW (cold rolled electric welded) tubing. This is the most common and least expensive type of steel tubing available.

For the long answer, a lot of people have asked me why I don't use higher grade materials such as 4130 (cromoly) or DOM (mild steel "drawn over mandrel") both of which are stronger than mild CREW tubing.

Here is where I usually loose people in the discussion... the first thing to understand is the difference between "strength" (yield strength) and "elasticity" (modulus of elasticity) and why they are different properties, yet still important. The best explanation for each of these properties is to describe them in terms of motorcycles. Elasticity is what we experience when we feel the frame flex. The metal moves a small amount, then moves back to its original location. Strength is what is experienced when a motorcycle is crashed and the frame gets bent. The material has been moved a large distance and doesn't move back. It has "yielded".

So with those two conditions in mind, I will say that both mild steel and 4130 cromoly steel are both nearly identical in terms of their modulas of elasticity. In other words, you would feel the same amount of frame flex riding a motorcycle made from cromoly as you would on a motorcycle made from mild steel. Both materials will flex nearly the same amount under small forces. The difference is when you crash, mild steel will bend (and not bend back) sooner than with the higher grades of steel.

Because of this, I use mild steel. It is cheaper, easier to source, and much easier to fabricate (because of the lower strength). The well known moto author Kevin Cameron once described it something like this... "Cromoly is only an advantage if you can crash hard enough to bend mild steel, but not hard enough to bend cromoly".:ride

Thanks for the question:thumbup

 

[Frame Maker]

is there a weight advantage to cro-mo over mild steel tubing?

Thanks for two more really good questions...

Since mild steel and cromoly are virtually the same density (weight per volume), the general answer is that there is no direct weight advantage. That said, its common knowledge that there are some applications where weight is a primary concern. In those cases you must consider all three properties and what tradeoffs you are okay with.

Bicycles and aircraft are two examples where weight and strength are both very important. For those applications you will almost always see use of cromoly (or similar high grades of steel) used. Because both bicycles and aircraft are optimized for highest strength with the least amount of weight, the tradeoff is in allowing for flex. So weight savings is very much a factor of design priorities. Motorcycles tend to be prioritized for both strength and reducing flex. Commercially available motorcycles are also designed for ease of manufacturing. So with motorcycles, weight savings becomes a lower priority.

With my frame design, I could switch to cromoly steel while reducing the wall thickness and gain some weight savings without sacrificing strength. I would however see a reduction in stiffness and in increase in difficulty to construct. So everything becomes a tradeoff based on design priorities.

...what about your "sourced" cnc parts from overseas ? is there a choice in the alloys used? how is the quality control vs price point ratio?

I'd say that 20 years ago it would be a crap shoot trying to get Chinese made parts reliably made from a specific alloy. These days the reliability has greatly improved. So not only can I specify the alloy, but also the temper. As an example, with my last batch of parts I specified "6061 aluminum". Here in the US it is implied that you want 6061-T6 since T6 temper is the most common way of supplying wrought aluminum. My Chinese vendor assumed I wanted T0 (soft annealed state). Luckily I caught this and was able to clarify 6061-T6 (which is slightly more expensive from this vendor).

As for quality vs price, its like everywhere else. I've seen some extremely nice quality CNC machined parts from Chinese vendors, but its expensive (still cheaper than US). And I've seen low quality CNC machined parts that were dirt cheap. The vendor I've been using is closer to this. I want my parts to look nice, but they aren't being used on SpaceX so I'm okay if the quality and accuracy isn't the absolute best.

 

[auntiebling]

oooh. nerd speak. i can participate!?

is there a weight advantage to cro-mo over mild steel tubing?

they have the same density, so unless you optimize every tube for needed strength vs material dimensions there will not be any weight change.

4130, the usual suspect when people say cro-mo (there are dozens) has significantly higher yield strength than mild steel. It Depends (the favorite phrase of engineers and those that like to be scienc-y) on which specific mild steel, and which heat treat condition the 4130 is in but it's safe to say 4130 is at least 30% higher yield strength. it can easily be nearly double.

it is a pretty complicated subject but if you're really lucky, a 30% weight reduction could be realized if the design were optimized for cromo. it would be a LOT of work just in the Figuring It Out stage, and as julian mentioned the material cost is higher, harder to work with in every way.

a reasonably easy way to observe this difference is with bicycles. a high end steel frame bike frame weighs 5 lbs or less. a department store bike frame of similar proportions will weigh 10, maybe more.

the difference is in the individual tubes. often the wall thickness varies along the length of the tube, thicker on the ends and thinner in the middle and quite thin to begin with. on the department store bike, the tubes have overall thicker walls, do not vary in section along the length.

for grins i looked at mcmaster carr (probably the most expensive place to buy but should illustrate the difference) using some arbitrary dimensions. today a 6 foot piece of mild steel 7/8" OD .0625 wall is ~$12

the identically dimensioned tube in 4130 is $38

 

[bergmen]

As a Mechanical Engineer for the past 30+ years I enjoy attending the Frame Maker technical seminars here. I always learn something and thank you for taking the time to carefully explain everything!

In my experience, I had difficulty in accepting material certifications from Chinese fabricators. The ones I did receive appeared to be fabricated. I simply did not trust them (and I had corroboration from some domestic Chinese sources). As a result, I went with domestic fabricators with real, honest material certs. More expensive but quality guaranteed. Customer appreciated it as well.

Dan

 

[Frame Maker]

Here's a mini project update.

Remember the frame revisions I was doing in CAD a few weeks ago. I had created an aluminum mid-frame and modified front engine mounting plates...

rz350 frame image 20210112.5 by andbike, on Flickr

Yesterday I received the 3D prints that I will use to verify these design changes before investing in CNC machined aluminum parts. The 3D prints are good insurance for catching potentially expensive mistakes before they happen.

20210202_115939 by andbike, on Flickr



Back of the side plates.

20210202_120159 by andbike, on Flickr



In the next few days I'll be doing some test fitting with the 3D prints and making any necessary adjustments to the CAD model.

arty

 

[Frame Maker]

As a Mechanical Engineer for the past 30+ years I enjoy attending the Frame Maker technical seminars here. I always learn something and thank you for taking the time to carefully explain everything!

Hah! Thank you:thumbup

In my experience, I had difficulty in accepting material certifications from Chinese fabricators. The ones I did receive appeared to be fabricated. I simply did not trust them (and I had corroboration from some domestic Chinese sources). As a result, I went with domestic fabricators with real, honest material certs. More expensive but quality guaranteed. Customer appreciated it as well.

Dan

I can't say that I disagree, except to say that quality (and honesty) of Chinese manufacturing has improved in recent years. I'm still not 100% sure that I'm getting exactly the alloy that I specify. If I ever have doubts about a part with a very low safety margin my plan is to design a test slug into the geometry of the part. The slug will be connected by a very small web to the main part. That way I can break off the slug and test it compared to a known material of the same dimension. However, for the majority of my moto projects I feel comfortable with the quality.

Here's an interesting story that I'll add... A few years ago I was working on a small medical instrument that would be housed within an aluminum extruded housing. I was working with a local engineering team, but the end customer was a Japanese company. Since historically the Japanese don't like the Chinese, we were told to have the device manufactured anywhere in the world except China. This was great news at first. We were proud that we could have it MADE IN USA!.

Thats when the problems started. We sent out RFQs to several domestic aluminum extrusion vendors and made a selection. We kicked off the tooling and waited for samples to arrive. Well, we waited and waited and waited then finally samples arrived... and they were bad! This was the beginning of much more waiting, lots of poor communication, and more samples that weren't correct. Out of frustration we contacted an independent industry consultant and explained the problems we were having. His solution was simple... go to China and problems will go away.

I few years ago I was in China for a work related project and took a tour of a top tier aluminum extrusion facility. I have also toured domestic extrusion factories. The Chinese facility was amazing in the breadth of what they could do and the post opp services they offered were surprisingly sophisticated. The part I was working on was a very large and complex profile with multiple open and closed cavities. This was no problem to extrude except that we need an extreme bend formed on one end. They were ably to construct the most complex mandrel bending dies I have ever seen and successfully bent our parts to a very high degree of precision. It was very impressive to see and a pleasure working with them.

I am very proud to say that my experiences working in China have been amazing and I have made some very close personal friends there.

mmexport1553485015339 by andbike, on Flickr

 

[chrisweir.com]

Thank you for this amazing content! I want to ride it! :afm199

 

[bergmen]

I need to clarify - my personal experiences (with my own project, not the company's) was about 15 years ago. Forgot that it has been that long. Things have evolved dramatically since then and many sources are leading-edge hi-tech for sure.

Very interesting story on the extrusion company in China. I'm not sure where we source our extrusions (our vacuum manifolds on our gas phase mass specs are extruded) but they are of excellent quality.

Dan

 

[DannoXYZ]

As with any project, it's best to stay on top of specs. Problems I've had with any manufacturer was lack of detailed specs and making sure samples meet those specs.

About 20-yrs ago, I had some automotive EFI systems designed in NZ and manufactured in China. Along with friend who made high-end home-theatre equipment. Didn't stay on top of specs and first samples where horrible! I tightened up and made my requirements more stringent and results were much better. Similar to your 6061-T6 vs. T0 example.

A lot of urban-legend and stereotypes of bad Chinese products was due to greedy U.S. importers. Things like home/auto electronics, aftermarket auto/moto-parts, etc. So you've got Napa Auto Parts or AutoZone going to Chinese suppliers and asking for lowest-specs possible for cheapest costs. Then marked up as much as market will support for biggest profits. High failure-rates ensues and everyone (including politicians) points their finger at "Made in China" label.

The manufacturing-location is really irrelevant, it's specs the importer wants that determines how product will perform. Heck, you can get crap products made anywhere, Thailand, Germany, Poland, even in U.S.A!!! When I made headlight/wiring-harness upgrades for Porsches with 50-year warranty, I knew exactly which components and manufacturing processes were needed. It certainly wasn't made from stuff found on shelves at FLAPS.

 

[Joshman]

I don't know how I missed this thread, but I'm glad I found it.

I'm excited to see the progress Julian!

 

[Frame Maker]

As with any project, it's best to stay on top of specs. Problems I've had with any manufacturer was lack of detailed specs and making sure samples meet those specs.

About 20-yrs ago, I had some automotive EFI systems designed in NZ and manufactured in China. Along with friend who made high-end home-theatre equipment. Didn't stay on top of specs and first samples where horrible! I tightened up and made my requirements more stringent and results were much better. Similar to your 6061-T6 vs. T0 example.

A lot of urban-legend and stereotypes of bad Chinese products was due to greedy U.S. importers. Things like home/auto electronics, aftermarket auto/moto-parts, etc. So you've got Napa Auto Parts or AutoZone going to Chinese suppliers and asking for lowest-specs possible for cheapest costs. Then marked up as much as market will support for biggest profits. High failure-rates ensues and everyone (including politicians) points their finger at "Made in China" label.

The manufacturing-location is really irrelevant, it's specs the importer wants that determines how product will perform. Heck, you can get crap products made anywhere, Thailand, Germany, Poland, even in U.S.A!!! When I made headlight/wiring-harness upgrades for Porsches with 50-year warranty, I knew exactly which components and manufacturing processes were needed. It certainly wasn't made from stuff found on shelves at FLAPS.

Yes, yes, and yes. My experiences have been very similar.

Even with good specs, its still funny what can happen. I'll never forget sending out drawings for RFQ to a domestic shop. The drawings had big bold text that clearly stated "FOR QUOTE ONLY". We didn't hear anything for a few weeks, then they finally called and said our parts were ready... that was super weird.:wow