RC excavator CAT 320 build blog - Page 5 - RC Groups
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Dec 24, 2012, 07:57 AM
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I have tested the motors and tracks today. The tracks are working really well.
For the LED lights, I use a Robbe module to control 2 light groups.

Here is a short video:
RC Excacator Test of the tracks and lights (0 min 43 sec)


The motors I used are the RB-Cyt-27 from Cytron (12V 130RPM 8oz-in Spur) but they are way too WEAK !! So I will have to look out for an alternative motor, preferably small AND powerful.

The motor on the 360 swing from CTI-Modellbau is also too weak. I am thing to use an RB35 motor that drives the CTI pinion via a wormwheel.
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Dec 24, 2012, 07:47 PM
in memory of dez RIP
rcphreak's Avatar
brushless out runner motors will give you what you need and also small in size
Dec 24, 2012, 07:54 PM
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Quote:
Originally Posted by rcphreak
brushless out runner motors will give you what you need and also small in size
are they available in low rpm? like 30 to 50 rpm?
Dec 24, 2012, 08:40 PM
in memory of dez RIP
rcphreak's Avatar
kv ratings will varry you will be looking for a low kv rating the lower the better . but through gearing and batterys you could achive your needs . remember kv = rpm x volts . but 40 to 50 rpm is unheard of . you may look into some type of hydrolic motor for such a low rpm and to have the torq required to move this heavy unit .

so for reference if you use a 400 kv motor and say a single cell 5000mah lipo 400 x 3.7 will give you 1480 unloaded rpm with gearing could be where you need to be and would have gobbs of torq another method would be to use a 7.4v while giving more rpm you could limit your epa to achive the desired speed and increase torq .
Last edited by rcphreak; Dec 24, 2012 at 10:13 PM.
Dec 27, 2012, 06:02 PM
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I decided to give my excavator a paint job . I've now completely taken it apart and am preparing everything for the primer.

I'm still waiting for the missing pieces for the motor / pump. The pump came with a speedcontroller for the motor. I still have to check if has BEC in it or not. I also purchased the optional module that allows the motor to run with 2 speeds so that the pump does not always have to run at full speed.

I'm controlling the excavator with a Spektrum DX6i and 2 receivers (Dig and Drive)

The Drive receiver will control the 2 motors that drive the tracks, the swing and the lighting.

The Dig receiver will hold the 3 dig movements (boom, arm, bucket) and the pump. according to the instructions I will need a multiswitch in order to allow to control the 2 speeds for the pump.

If I understand well, the optional 2 speed module can not be connected to the receiver. It needs to be controlled by the multiswitch.
Dec 28, 2012, 06:50 AM
Registered User
I made a video of the test I did with the hydraulic pump motor. The motor, when switched on, starts at a low rpm. When the sticks are used, the motor rpm increases.
Hydraulic pump motor test (1 min 4 sec)


I enabled the 2 mix modes of the spektrum dx6i and linked them to the arm and boom position. Ideally I would need a 3rd mix mode for the bucket operation. Not sure how allow to increase the motor rpm when only operating the bucket curl.

I also finished the arm and boom for painting:

Dec 28, 2012, 01:29 PM
Lets get the HUEY up
madphil's Avatar
This is a great build thread the arms look good now they have been sanded down ( would you consider fitting countersunk screws in the arms for a more scale like appearance when painted ?? )
Dec 28, 2012, 02:42 PM
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Quote:
Originally Posted by madphil
This is a great build thread the arms look good now they have been sanded down ( would you consider fitting countersunk screws in the arms for a more scale like appearance when painted ?? )
Hey Madphil, I actually like the screws as they are ... but of course countersunk screws could be used on the model.
Dec 30, 2012, 02:39 PM
Registered User
I modified the "360 swing" as the motor from CTI-Modellbau can not handle the weight of the excavator. I installed a wormwheel that is connected to an RB35





Dec 31, 2012, 08:25 PM
in memory of dez RIP
rcphreak's Avatar
worm dive may help your motors cope with the loads have you looked into the 24v impact and drill motors used in todays cordless power tools ???? most are brushed and seem to handle large loads .
Jan 01, 2013, 12:21 AM
Registered User
great build it looks great looks like you put a lot of time in to it
Jan 04, 2013, 12:13 PM
Registered User
I am almost finished preparing all the parts for painting. I received the missing parts for the hydraulic pump today. I still need to put the track motors on the undercarriage and then painting can start

Jan 04, 2013, 12:45 PM
Team of ONE....or...Team Me
DeadTom's Avatar
Looking good, are you going with the yellow Cat look?
Jan 06, 2013, 12:40 PM
Registered User
Quote:
Originally Posted by DeadTom
Looking good, are you going with the yellow Cat look?
yes indeed it will get the yellow/black with red stipe color


try-out.....







still work in progress. I need to do the roof part and make a hole in the aluminum
Jan 06, 2013, 06:11 PM
Registered User
Ready!!









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