mbba2002

My Feedback: (10)

JUST WAT THE TOPIC SAYS. NO HISTORY ONLY TRUE CNC QC REAR ENDS ONLY. I would like TO KNOW WHO HAS MADE THEIR OWN QC REAR END MANUAL MACHINE OR CNC ONLY. LETS SEE THEM

EXAMPLE:

Pigsmightfly

Think it's time you showed your work to us to prove your not just an ego on legs

I'll show you mine if you show me yours..........

Acs_guitars

My Feedback: (3)

I would really like to see some of pics of the 1/4 QC rears inside and out.... Weather it is a factory made, or hand made, I don't care, lets just see some pics. Skellenger, Raco, QRS, New Era (skellenger copy)..... they are all good

randyg-rcu

I too would be most interested in detailed internal photos of rear ends... (god, that didn't come out right.

--Randy

NitroWolf

Were the early New Era, Skellenger, Raco...rears positive traction (locked). If so, did this hurt performance on road courses? It seems that a limited slip type would be the way to go on courses.

quarterscalelegends

Yea, they were all posi traction. The racers used a larger tire on the right rear to help the car turn better in oval racing. Raco Europe made a european diff that used thrust bearings and those were used in the GTP and Indy car classes, but the stock car oval has always been the most popular. The european diff will fit in the raco, new era and skellenger rear ends maybe also the H&L, but not positive, I will have to look. Here are a couple pics of internals. I will take some more of my rears later

mbba2002

My Feedback: (10)

Stick with the TOPIC. NO HISTORY!!!!!!!!!! ONLY CNC OR MANUAL MADE QC REAR ENDS ONLY!!!!!!!

mbba2002

My Feedback: (10)

The skellenger rear ends did come with a limited slip diff and Raco too.

NitroWolf

Man, those look like full scale rears. They also look to heavy for 1/4 scale, but I guess they are very realiable?

Acs_guitars

My Feedback: (3)

of course they look like full scale.... they are true scale parts. Not like anything on the current larger scales out there, these were actually scaled down from a full size for both look and function.

NitroWolf

So, you are saying that they are heavy also? Probably to heavy to be competitive in today's 1/4 scale racing?

quarterscalelegends

The skellenger weighed only 2 pounds. The H&L was about 3.5 pounds. The Qrs rear was light, but plastic and was brittle. Here is a pic of a few different rears I had in a cabinet so you can see the different sizes. I also added a pic of a skellenger in my pacesetter funny car and a CNC rear in my QRS that uses the QRS straight cut gears. The Rears that dont look like QC style are pacesetter worm gear drives.

mbba2002

My Feedback: (10)

Forum Members stick to the topic.

quarterscalelegends

lightfoot, thanks for editing the pics so they were not so big. What did I do wrong?

randyg-rcu

Excellent photos; keep them coming.

Hrmm, flaw in plan... I've got to get a working mill before I even think about maching one, don't I?

--Randy

mbba2002

My Feedback: (10)

NOT RELATED TO THE TOPIC. This topic is for anyone who has made their own QC rear end. NO HISTORY[:@]

quarterscalelegends

Randy, do you have a mill that you are trying to convert to CNC?

randyg-rcu

Nah. Going to build entirely from scratch. Have I mentioned I like scratch-building things?

The motor control and the like is easy (remarkably identical to my giant-scale servo controller, actually... hell, I'll probably even use car windshield wiper motors (like I use for servos) to drive the lead screws, with optical encoders for positioning), and 2.5d tool path generation doesn't seem too hard... true 3d tool path generation, and anything greater than 3 axis, however, makes my brain hurt developing the path generator algorithms... good thing the first mill is only going to be 3 axis.

The plan is to build a really crappy mill with random bits of aluminum and a carbide endmill in my dremel tool, then use that to machine slightly-less-crappy parts to build a slightly-less-crappy mill, and so on until I have an only-marginally-crappy mill.

Then I can start work on r/c car parts...

(the car I'm building right now just uses a chain to the rear diff, and doesn't use any fancy machining, so I'll probably have it finished before I finish the mill...)

Actually, first thing I need to do is find a new job. Right now I can't afford bloody anything.


--Randy

quarterscalelegends

There are free or near free programs on the net for your pc to run the motors. But everyone for the most part uses stepper motors. I dont think windshield motors will work. Stepper motors will hold a position without moving and it takes a bunch of force to move them. I bought a Chineese mill a couple years ago. I then bought a controller board, 3 sanyo stepper motors and I made the brackets. I use a 15.00 PC I got off ebay and the software was free! You would be amazed at what you can make with a cheap setup. Good luck!

randyg-rcu

I've been remarkably happy with windshield wiper motors though... and not too pleased with steppers. (plus I abhor open-loop systems)

I didn't see any free *nix programs that do tool path generation... do you know of any specifically?

I'd never use the pc to directly run the motors; that would require real-time control... I'd much rather just build another hc11-based board like I designed for giant-scale servos, and have the PC send instruction to it over the serial port. the microcontroller will keep track of all the motor positions, acceleration, deceleration, etc, and the pc just has to say "move axis X to position Y at rate Z", pretty much. that way no real-time control is required on the pc.


Anyway, the harder I make it, the more I learn.


--Randy

M.R. Ogle

YIKES!!!!

You guys might as well be speaking martian. Over my head!

MRO

quarterscalelegends

have you been on CNC zone.com? That site is pretty good. I use a cad program and save as DXF and import into my CNC software and it generates the G-Code. Sounds like you have a seriouse project on your hands. I went the easy way, I was not interested in turning it into another hobby!

M.R. Ogle

... you say you can use a CAD program, export as DXF, import the info into a CNC and you can find the G-spot?

I KNEW there was an easy way!!!!!!

LOL

MRO

randyg-rcu

Nah. not martian. just nerd.


randyg-rcu's half-assed glossary:

CNC mill: a complicated-looking toy that lets you design your parts on the computer, press a few buttons, clamp a block of metal to it, and have the perfect part come out a few hours later.

3 axis mill: A mill consisting of an XY table (i.e. able to move left/right and front/back) and a Z acutator, usually moving the cutting tool up and down. Can not cut at angles or any other fancy features.

2.5D: A 2.5 dimensional object is one that can be represented as a table of heights, such as a list of the thickness of the object for every xy coordinate. Such surfaces are extremely easy to mill, as they can not have overhangs, angles, or any other difficult features.

Tool path generation: Hard-to-write code that takes your 3d object as input, and outputs the exact path to move the cutting tool to cut out that object. For 2.5D surfaces, this is easy, but it's a non-trivial problem when you have overhangs and other non-pleasant object designs.

Motor control: In order to move all the XY table and Z stage, you have to have motors. And these motors will need a circuit board to control them. One approach is a dumb circuit board, where the computer sends real-time instructions on how to turn the motors. The other option is a smart board, that is far more work to build, but takes some of the load off the computer, and does not require the computer to run a real-time operating system.

Windshield wiper motors: Consist of a dc permanent magnet motor with a worm-gear reduction. Due to the high-ratio worm gear reduction, they can be positioned relatively accurately. However, you have to use an encoder of some form to monitor their position/rotation.

Stepper motors: A motor that rather than spinning continually, moves in discrete steps.

Open-loop: A design whereby the computer has no feedback about the motor position. All it knows is that it told the motor to move, but not whether it actually moved or how much.

Closed-loop: Having encoders or other devices that actively monitor the motor position/rotation.

HC11: A motorola microcontroller, that I like using for projects like these. Think very small computer.

Lead screws: Allthreads. Threaded rods. whatever they're called in your local dialect, they're rods with threads the entire length, and are useful for building parts of mills. Simply put a nut on the bottom of something, then turn the rod, and it will move that something.

Optical encoders: devices that generate pulses as the shaft rotates, which can be used to keep track of position by counting the pulses. Easy to steal out of old mice.

*nix: UNIX, Linux, or any varients. Real operating systems that are fast, secure, and reliable. Contrast windows, which is none of the above.

Bodge: half-assed; kluge; marginal; held together with duct tape and bailing wire.

G-spot: two fingers, curl upwards, few inches in. Feels slightly rougher. In a closed-loop design, feedback is provided by moans to indicate correct actuator positioning.


Did I miss any?

*fluffs his tail tiredly and heads off to bed*
--Randy

mbba2002

My Feedback: (10)

I only see talk to making a CNC QC rear ends NO picture like I wanted???????????????????
Where's THE PROOF TO XKNACX'S STATEMENT??????????????????