Bruder Cat Excavator Threaded Rod
 

Hi,

Im trying to convert a Bruder excavator using threaded rod but everything i try seems to fail.

The first threaded rod i tried worked but it took forever for the servo to unwind it as the thread was too small. I then tried to use a drill bit but just could not get that to run smooth.

Can anyway tell me where i can buy threaded rod with the correct thread for this conversion? Or even better anyone who makes and sells the parts needed to make this conversion work?

Thanks

Re: Bruder Cat Excavator Threaded Rod
 

This thread may be able to help or at least rockNmayhem may be able to help. Click Here

Travis

Re: Bruder Cat Excavator Threaded Rod
 

Hey There
Have you had any luck with the threaded rod ?
I've done a few builds,along with the bruder excavator with screwdrives,I use 1/2 ,3/8 SST tubing 0.035 wall along with 1/4 wood auger bits ,high torque servos converted to 360 .have any questions feel free to ask.:)
Tommy

Re: Bruder Cat Excavator Threaded Rod
 

Thanks guys ill have a look at the wood auger bits.

Re: Bruder Cat Excavator Threaded Rod
 

Hey pumptech I have been searching for those wood auger bits everywhere but I can't find them. I live in California and they don't have them in any Lowes or Home Depot u have a link to a web page I might be able to order them from?

Also I am looking into threaded rod as an option. But with a geared motor as opposed to servo

Re: Bruder Cat Excavator Threaded Rod
 

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 :D

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

Re: Bruder Cat Excavator Threaded Rod
 

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:p) 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

Re: Bruder Cat Excavator Threaded Rod
 

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).

Re: Bruder Cat Excavator Threaded Rod
 

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! :o, 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!

Re: Bruder Cat Excavator Threaded Rod
 

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.

Re: Bruder Cat Excavator Threaded Rod
 

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

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

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

http://images.lowes.com/product/conv...38101015lg.jpg

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!???!?!?.....

http://www.sciplus.com/itm_photos/38143-websm.jpg

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

38143 6 VDC MABUCHI MOTOR

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


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?