[etal]

After discussions with a mechanical engineer friend I've decided to make myself a set of RFX A-Type rockers (lower BB and slack HA as seen on this thread ). I figured I might as well make a few more if there is enougth interest on the forum.

Material will be aluminum (probably 2024) with hard-ano finish (grey) , price to be determined later.

Anyone else interested?

Also if anyone has exact measurments/drawings I would be very interested.

 

[Renegade]

I'm curious; why 2024? Why not 6061?

 

[Lucky7]

I also wonder why you wouldn't use 6061 or 7075 aluminum. My next question is, will the plates be straight plates like mine and Renegades or taper in like standard Turner plates?

Bryan

 

[Renegade]

I don't have measurements for 'A' rockers, my stock rockers are 'B' rockers. You might check this thread and see if there's any info you can get from it.

If you do make them from 2024, be sure to follow through with anodizing them. Allthough 2024 has many favorable characteristics, it rates very poorly in regards to corrosion resistance if it's left uncoated.

 

[etal]

I don't have measurements for 'A' rockers, my stock rockers are 'B' rockers. You might check this thread and see if there's any info you can get from it.

If you do make them from 2024, be sure to follow through with anodizing them. Allthough 2024 has many favorable characteristics, it rates very poorly in regards to corrosion resistance if it's left uncoated.

Thanks for the link Renegade.

The plan is to use 2024 simply because the machinist can get it for real cheap and since I want to do the tapered version material cost plays a bigger part. Since they are going to be anodized corrosion should not be a problem. Are there any other disadvantages to using 2024?

Erez

 

[Renegade]

Aside from the corrosion resistance thing, there doesn't appear to be any disadvantages to using 2024. It's an alloy that is used in many industries, including aerospace. The first machine shop that I worked in, which was within a medical instruments company, used 2024 excusively. Since then, I have not run across it much; most of the time now it's 6061 or 7050/7075.
Yes, since you are making curved rockers, your material costs will be higher than if you were making flat rockers. One inch material should be significantly more expensive than 3/8 thick material.

 

[Bulldog]

I'll take a set of "B" rockers that can clear a 7.5x2.25 Avalanche Chubbie! Anno black please.

 

[airwreck]

seems to me the sixpack rocker would be the one to copy.

Type A rockers on my 02 RFX allow the rear tire to contact the deraileur stop on the seat tube.

Has anyone done a comparison of the two different original rfx rockers and the sixpack rockers?

 

[Renegade]

Warning! High geek factor info posted below!

2024:
Key Words: Aluminium 2024-T6; UNS A92024; ISO AlCu4Mg1; AA2024-T6

Component Wt. %


Al 90.7 - 94.7
Cr Max 0.1
Cu 3.8 - 4.9
Fe Max 0.5
Component Wt. %


Mg 1.2 - 1.8
Mn 0.3 - 0.9
Other, each Max 0.05
Other, total Max 0.15
Component Wt. %


Si Max 0.5
Ti Max 0.15
Zn Max 0.25


Material Notes:
Weldability = C; Stress Corrosion Cracking Resistance = B; General Corrosion Resistance = D (A = best; E = worst). Good machinability and surface finish capabilities. A high strength material of adequate workability. Has largely superceded 2017 for structural applications.

Uses: Aircraft fittings, gears and shafts, bolts, clock parts, computer parts, couplings, fuse parts, hydraulic valve bodies, missile parts, munitions, nuts, pistons, rectifier parts, worm gears, fastening devices, veterinary and orthopedic equipment, structures.

Some data provided by Alcoa.

Data points with the AA note have been provided by the Aluminum Association, Inc. and are NOT FOR DESIGN.

Click here to view available vendors for this material.

Physical Properties Metric English Comments


Density 2.78 g/cc 0.1 lb/in³ AA; Typical

Mechanical Properties


Hardness, Brinell 125 125 500 kg load/10 mm ball
Hardness, Knoop 157 157 Estimated from Brinell
Hardness, Rockwell A 48 48 Estimated from Brinell
Hardness, Rockwell B 78 78 Estimated from Brinell
Hardness, Vickers 142 142 Estimated from Brinell
Tensile Strength, Ultimate Min 427 MPa Min 61900 psi
Tensile Strength, Yield Min 345 MPa Min 50000 psi
Elongation at Break 5 % 5 %
Modulus of Elasticity 72.4 GPa 10500 ksi Estimated from other heat treatments.
Poisson's Ratio 0.33 0.33 Estimated from other heat treatments.
Fatigue Strength 124 MPa 18000 psi 500,000,000 cycles; completely reversed; R. R. Moore Machine and specimen.
Machinability 70 % 70 % 0-100 Scale (A=90; B=70; C=50; D=30; E=10)
Shear Modulus 27 GPa 3920 ksi Estimated from similar Al alloys.
Shear Strength 283 MPa 41000 psi

Electrical Properties


Electrical Resistivity 4.49e-006 ohm-cm 4.49e-006 ohm-cm AA; Typical at 68°F



6061:

Subcategory: 6000 Series Aluminum Alloy; Aluminum Alloy; Metal; Nonferrous Metal

Close Analogs:

Composition Notes:
Aluminum content reported is calculated as remainder.
Composition information provided by the Aluminum Association and is not for design.

Key Words: al6061, UNS A96061; ISO AlMg1SiCu; Aluminium 6061-T6, AD-33 (Russia); AA6061-T6; 6061T6, UNS A96061; ISO AlMg1SiCu; Aluminium 6061-T651, AD-33 (Russia); AA6061-T651

Component Wt. %


Al 95.8 - 98.6
Cr 0.04 - 0.35
Cu 0.15 - 0.4
Fe Max 0.7
Component Wt. %


Mg 0.8 - 1.2
Mn Max 0.15
Other, each Max 0.05
Other, total Max 0.15
Component Wt. %


Si 0.4 - 0.8
Ti Max 0.15
Zn Max 0.25


Material Notes:
Information provided by Alcoa, Starmet and the references. General 6061 characteristics and uses: Excellent joining characteristics, good acceptance of applied coatings. Combines relatively high strength, good workability, and high resistance to corrosion; widely available. The T8 and T9 tempers offer better chipping characteristics over the T6 temper.

Applications: Aircraft fittings, camera lens mounts, couplings, marines fittings and hardware, electrical fittings and connectors, decorative or misc. hardware, hinge pins, magneto parts, brake pistons, hydraulic pistons, appliance fittings, valves and valve parts; bike frames.

Data points with the AA note have been provided by the Aluminum Association, Inc. and are NOT FOR DESIGN.

Click here to view available vendors for this material.

Physical Properties Metric English Comments


Density 2.7 g/cc 0.0975 lb/in³ AA; Typical

Mechanical Properties


Hardness, Brinell 95 95 AA; Typical; 500 g load; 10 mm ball
Hardness, Knoop 120 120 Converted from Brinell Hardness Value
Hardness, Rockwell A 40 40 Converted from Brinell Hardness Value
Hardness, Rockwell B 60 60 Converted from Brinell Hardness Value
Hardness, Vickers 107 107 Converted from Brinell Hardness Value
Ultimate Tensile Strength 310 MPa 45000 psi AA; Typical
Tensile Yield Strength 276 MPa 40000 psi AA; Typical
Elongation at Break 12 % 12 % AA; Typical; 1/16 in. (1.6 mm) Thickness
Elongation at Break 17 % 17 % AA; Typical; 1/2 in. (12.7 mm) Diameter
Modulus of Elasticity 68.9 GPa 10000 ksi AA; Typical; Average of tension and compression. Compression modulus is about 2% greater than tensile modulus.
Notched Tensile Strength 324 MPa 47000 psi 2.5 cm width x 0.16 cm thick side-notched specimen, Kt = 17.
Ultimate Bearing Strength 607 MPa 88000 psi Edge distance/pin diameter = 2.0
Bearing Yield Strength 386 MPa 56000 psi Edge distance/pin diameter = 2.0
Poisson's Ratio 0.33 0.33 Estimated from trends in similar Al alloys.
Fatigue Strength 96.5 MPa 14000 psi AA; 500,000,000 cycles completely reversed stress; RR Moore machine/specimen
Fracture Toughness 29 MPa-m½ 26.4 ksi-in½ KIC; TL orientation.
Machinability 50 % 50 % 0-100 Scale of Aluminum Alloys
Shear Modulus 26 GPa 3770 ksi Estimated from similar Al alloys.
Shear Strength 207 MPa 30000 psi AA; Typical

Electrical Properties


Electrical Resistivity 3.99e-006 ohm-cm 3.99e-006 ohm-cm AA; Typical at 68°F

Thermal Properties


CTE, linear 68°F 23.6 µm/m-°C 13.1 µin/in-°F AA; Typical; Average over 68-212°F range.
CTE, linear 250°C 25.2 µm/m-°C 14 µin/in-°F Estimated from trends in similar Al alloys. 20-300°C.
Specific Heat Capacity 0.896 J/g-°C 0.214 BTU/lb-°F
Thermal Conductivity 167 W/m-K 1160 BTU-in/hr-ft²-°F AA; Typical at 77°F
Melting Point 582 - 652 °C 1080 - 1205 °F AA; Typical range based on typical composition for wrought products 1/4 inch thickness or greater; Eutectic melting can be completely eliminated by homogenization.
Solidus 582 °C 1080 °F AA; Typical
Liquidus 652 °C 1205 °F AA; Typical

Processing Properties


Solution Temperature 529 °C 985 °F
Aging Temperature 160 °C 320 °F Rolled or drawn products; hold at temperature for 18 hr
Aging Temperature 177 °C 350 °F Extrusions or forgings; hold at temperature for 8 hr






CTE, linear 68°F 23.2 µm/m-°C 12.9 µin/in-°F AA; Typical; Average over 68-212°F range.
CTE, linear 250°C 24.7 µm/m-°C 13.7 µin/in-°F Average over the range 20-300ºC
Specific Heat Capacity 0.875 J/g-°C 0.209 BTU/lb-°F
Thermal Conductivity 151 W/m-K 1050 BTU-in/hr-ft²-°F AA; Typical at 77°F
Melting Point 502 - 638 °C 935 - 1180 °F AA; Typical range based on typical composition for wrought products 1/4 inch thickness or greater. Eutectic melting is not eliminated by homogenization.
Solidus 502 °C 935 °F AA; Typical
Liquidus 638 °C 1180 °F AA; Typical

Processing Properties


Annealing Temperature 413 °C 775 °F
Solution Temperature 256 °C 493 °F
Aging Temperature 191 °C 375 °F 8 to 16 hr at temperature

 

[tscheezy]

I second the suggestion for the 6-Pack rockers. Here is a 6-Pack front triangle mounted with Type B RFX rockers and stock 6-Pack rockers. Note the added height the B rockers would introduce. The Type A rockers are analagous to the Pack rockers, and more readily available for duplication.

 

[Renegade]

In case ant of you are wondering where the heck I stole all that properties info from, there is a nifty website you can check out by clicking here Use the search feature found in the upper right hand corner of the homepage.

 

[SSINGA]

seems to me the six pack rocker would be the one to copy.

Type A rockers on my 02 RFX allow the rear tire to contact the derailleur stop on the seat tube.

Has anyone done a comparison of the two different original rfx rockers and the six pack rockers?

Pics of six pack rocker (top) vs RFX rocker (bottom)which is apparently a B rocker.

 

[tscheezy]

That'd be the "B" version. The "A" version would probably superimpose nearly perfectly.

 

[airwreck]

can't tell because the pack rocker is in the way.
But it would make sense in the progression of the rocker design that the front one would drop the BB height compared to the one behind it?

 

[Roostalee]

Cool site. I've got an old Sampson hardtail that's made of CP4 titanium, and I've heard rumors that CP4 was a bad material to use for frame tubing (too brittle?), although it's sometimes still used in dropouts. Unfortunately, this site doesn't really allude to any of that, but it is nice to read that CP4 is good for use in pickling baskets!

I'd love to have a conversation with someone well-versed with CP4 and ti alloys.

Sorry to hijack the thread.

 

[airwreck]

The "A" version would probably superimpose nearly perfectly.

I don't think it would due to the tire contact issue.
These measurements may have been posted before, but here they are again and this time we'll add them to the rocker sticky.

'A' rocker approximate measurements mid hole to mid hole.
250mm, 190mm and 75mm

Not sure if adding more length corrected this issue.

 

[tscheezy]

In SSinga's pic, it is a B rocker. Here's the whole bike:

 

[Renegade]

Cool site. I've got an old Sampson hardtail that's made of CP4 titanium, and I've heard rumors that CP4 was a bad material to use for frame tubing (too brittle?), although it's sometimes still used in dropouts. Unfortunately, this site doesn't really allude to any of that, but it is nice to read that CP4 is good for use in pickling baskets!

I'd love to have a conversation with someone well-versed with CP4 and ti alloys.

Sorry to hijack the thread.

Sorry, I don't know anything about CP4.
I machine a lot of 6AL 4V titanium, which is a commonly used alloy, especially in the aerospace realm. Next to aluminum, it is the material I encounter the most these days.
3Al 2.5V is often used for Ti bike frames.

 

[G-AIR]

rfx rockers

I'll take a set of "B" rockers that can clear a 7.5x2.25 Avalanche Chubbie! Anno black please.

Bulldog,
I have a set of "B" rockers I am selling. HAMBONE was going to buy them but I haven't heard from him in over a week now.

Let me know if you are interested.

Thanks,
TIM
p.s. I also have 5" Rockers for sale. Shaheeb are you still interested?

 

[Jerk_Chicken]

Sorry, I don't know anything about CP4.
I machine a lot of 6AL 4V titanium, which is a commonly used alloy, especially in the aerospace realm. Next to aluminum, it is the material I encounter the most these days.
3Al 2.5V is often used for Ti bike frames.

CP grade is commercial grade, if I'm not mistaken. Much lower quality than the aerospace grades. I remember those old Mongoose Ti bikes in the late 90's used this grade in many areas of the frame, with the lower end models using commercial grade throughout.