Bruder Cat Excavator Threaded Rod

[paul1980]

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

[fhhhstix]

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

Travis

[pumptech]

Originally Posted by paul1980

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

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

[paul1980]

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

[edwalsh18]

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

[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?