Bruder Cat Excavator Threaded Rod

[Jigglepin]

Hi,

I tried threaded rod first also, but with some help i ended up doing it this way, please take a look at the link, it may help, or give you some ideas.

Happy building

http://www.scale4x4rc.org/forums/showthread.php?t=66312

[edwalsh18]

Originally Posted by Jigglepin

Hi,

I tried threaded rod first also, but with some help i ended up doing it this way, please take a look at the link, it may help, or give you some ideas.

Happy building

http://www.scale4x4rc.org/forums/showthread.php?t=66312

Hey JP thanks for the reply! great write up! i have seen almost every servo/drill bit setup on the internet (even in german and french forums) and that one finally painted the picture for me(mainly because i am slow) ok now even more i want to see someone if not me use a yoke to mount the bit to the servo so servo can be mounted stationary. i dont want my servos to move.

also JP if you have any info on your threaded rod attempt i would be interested in seeing what went wrong and what went good. i want to see if geared motors with threaded rod would reduce "slop"(i think thats the term). i seen in your video when changing directions the servo is going for a moment and bit is not moving. also, i want more power/speed. thanks again for response and any info u might have

[Vanisle]

I dont know anything about making a Bruder screwdrive model but I did briefly have a working Hanomag loader that used screwdrives. In regards to speed, the threaded rods (that drove the lift arms, bucket and to turn) were nice and fast. If I recall correctly, they were 10-32 thread and took approx one second to move one inch. If I understand the math correctly, that equates to approx 480 RPM ((60 seconds for RPM/4 seconds to move one inch) x 32TPI = 480 rpm). Of course, it used 380 sized motors so perhaps would not be practical for a hydraulic cylinder. A metric equivalent would be M5 threaded rod which is approx 31.75 TPI (25.4 mm/inch / .8 thread pitch = 31.75).

[Jigglepin]

Originally Posted by edwalsh18

Hey JP thanks for the reply! great write up! i have seen almost every servo/drill bit setup on the internet (even in german and french forums) and that one finally painted the picture for me(mainly because i am slow) ok now even more i want to see someone if not me use a yoke to mount the bit to the servo so servo can be mounted stationary. i dont want my servos to move.

also JP if you have any info on your threaded rod attempt i would be interested in seeing what went wrong and what went good. i want to see if geared motors with threaded rod would reduce "slop"(i think thats the term). i seen in your video when changing directions the servo is going for a moment and bit is not moving. also, i want more power/speed. thanks again for response and any info u might have

Hi,

Thanks alot! the play is just to do with no weight on it (especially the bucket tip mechanism, at the specific time I took the vid). When the strain is taken off, the rod will move slightly on the drill bit ( unless you use bigger grub screws to fill the gully in the drill bit, but somtimes it can lock up easily) but I wouldn't say it affects the overall function. When I was an absolute beginner and didn't have a clue about hydraulics and screw drives or even R/C for that matter! , I thought a threaded rod might have worked on a servo, after figuring out how to convert them to 360.

The main problem was trying to connect the rod somehow to the servo! once I figured out a temporary way to do it using tie wraps or similar, lol! I found that the servo took a life time to even turn the rod a few inches (unfortunately I dont have any vids/pics of my attempts). Thats when I went on the hunt and found out about using drill bits.

What exactly are you trying to achieve? surely trying to use a motor you would need room to gear it down etc, would you attach the rod to the servo/motor and a nut to the piece you're trying to move?

Happy building!

[edwalsh18]

Originally Posted by Jigglepin

What exactly are you trying to achieve? surely trying to use a motor you would need room to gear it down etc, would you attach the rod to the servo/motor and a nut to the piece you're trying to move?

Happy building!

yeah, i was thinking about running the motor straight to the threaded rod and a nut to the piece trying to move.

so finding the right motor/rod combo will be the trick. I will be looking into this more. what i will have to "research" is if the threaded rod will be the same as gearing down the motor. if a servo motor's gears gear down its motor to spin a wood auger drill bit (say for example) 1" per second then if i get a rod with x amount of TPI(thread per inch) i would need to get a motor that spins that same number of TPI per second to achieve the same as the servo.

[edwalsh18]

okay i did a search and i think i might have a good combo to try!!!
GOOD = CHEAP!!!! LOL!

here is the threaded rod, guessed at size and it says its $1.01!!! for 1 foot hehe why not?? i have done stupider things with a buck!

http://www.lowes.com/pd_160882-37672...3127881&***=32



Steelworks 3/16"Dia. x 36"L Threaded Rod

Zinc plated
Coarse thread
Threads Per Inch 20.0

okay so if it is 20 threads per inch and i want to move 1 inch per second then i need a motor that can spin 1200 rpm

20(tpi) x 60 (seconds per minute)= 1200rpm

.....

introducing the perfect motor to try!???!?!?.....



found here:
http://www.sciplus.com/category.cfm/...8/category/172

38143 6 VDC MABUCHI MOTOR

PRICE - A WHOPPING $2.95 for 3!!!!


This diminutive 6VDC Mabuchi motor draws 100 mA, approx 500mA at stall, and spins at approx 1240 rpm. The striated shaft is 1/2" long x 3/32" dia, in a housing that measures 1-3/16" x 1" dia. You get three for one great price for your science fair project, moving display, or latest invention.

might have to give it a shot. what you guys think?