The kit of this Robot Arm is well present and the instructions are better than I expected. IF you have the space, you should place each metal part in an easily identifiable pot so you do not, like me, have to keep referring to the page with the drawings on. Some screws are very similar and if you force in the wrong one, you are done for the day.
The motors are small and decent quality AND with suppression capacitors which is a nice touch too. If I have one a criticism here, it is that, at the end you have two motors with Blue/Black wiring BUT, in fairness, this is small beer and I mention it for completeness.
Build Your Own Robot Arm Review
If you have experience with other kits, such as TAMIYA models, you will feel right at home. Don’t rush at the first stage. The temptation is to build the 4 identical LOOKING gearboxes but wait, there are parts for 5 gearboxes and ONE of the 4 housings needs a different color OUTPUT gear, which is in a separate bag and you MAY at first think it is missing.
Also… There are 10 plain gear shafts in the kit and ONE of these is 2mm shorter than the other 9 and this short shaft is needed for the gripper. Use it in ignorance in the wrong place at your peril!
The kit simply falls together though it may tax the younger builder with the desire to rush the job. A warning here.. Do not over-tighten the self tapping screws as more rotation after the solid ‘stop’ is now drilling a hole and if you need to remove the screw for any reason, the plastic ‘thread’ will be severely weakened for next time. It’s plastic.. Not a titanium composite, treat it gently. Also… Use the right size cross head driver. IF you need to PUSH to stop the driver ‘camming out’ of the head, it’s the wrong size.
Electrically, the kit is very good quality. I was impressed that the weak solder joints of the wire to the battery terminals were secured with hot glue.. Nice touch. (Might use that in some of MY designs)
I followed the wiring instructions exactly, then decided I knew better and I reversed several of the motor directions by turning the plug round on the connector, because the motors seemed, to me, going in the wrong direction. This is why some games have a “REVERSE MOUSE DIRECTION” because we plane flyers like things a certain way.
Now, some of the points to be wary of. There are NO limit stops for the motors other than winding up the gears until they ‘ping’ or you stall the motor (unlikely as the gearing is VERY high, so a ‘ping’ it is then), or you break something, eventually. Keep the 3 year old grandchild well away, it’s a toy but not a TOY, OK? If you damage a gear or two, they MAY be hard to replace. The Manual suggests this is taken care of when the gears go “Da, Da, Da”, (and the dog says, “Gnu, Gnu”) so they are skipping (and wearing). It’s up to you.
The gripper is the thing to be gentle with in my view because the motors do overrun and the gripper can exert impressive gripping power (before things start to flex alarmingly). Forget picking up eggs unless you like the mess. Matchboxes or soft things will protect the gears. To “Da, Da”, or not to “Da, Da” that is the question ?
Likewise, do not try to lift the robot by the arm.. Hold it by the battery case and do not try to lift tins of baked beans. Stick to the weight limit. (100g).
Unnecessary load just hurts the gears, whatever the manual says.
Technical Notes:
- You MAY want to run this from a mains power supply and ditch the expensive D cells.?
- You need two off, THREE volt power supplies, as the motors are 3 volts and the 6 volt battery is centre tapped so the motors can be reversed. (+/- 3v)
- This is not a trivial task if you don’t understand electrics or electronics.
- The motors take around 1/4 amp each so with decent D cells, you can get bored long before the batteries flag.
- Rechargeable batteries output a lower voltage than dry cells so be ready for a small speed reduction if you use them.
- Changing batteries is easy.
I would LOVE to see an advanced version of this kit with potentiometers so I can determine the position of each motor as THEN, I can write some automated motion control for some of my PIC Microprocessor projects.
Note that the USB version of a similar kit just replaces the cheap switch box with a very expensive PC to do the same task, (and you don’t even get the switch box as an additional option)
You will NOT be able to program a motion towards a fixed point and stop… Not at this price.
So… Final comments
- Brilliant executive toy.
- Too fragile for a child (In my view).
- Fabulous introduction to parallelogram drives and motion control.
- It leaves me wanting a more ‘deluxe’ model with feedback, perhaps even stepper motors for that precision and maybe an all metal, cast and machined manufacture.
Worth the money, easily.
Now, for some wheels, radio control, and a camera !!!
