I have an issue with an mbot ranger I bought for my son. It seems the wheels at the front don’t allow enough movement. It seems to get stuck. Once I loosen the nut a little it operates normally for a while and then stops again. Beeps, tries to move again, stops and repeat. is there any advice on how to ensure they don’t over tighten ?
Problem with mbot ranger track / wheel tension?
Timb
#2
I have tried additional things to make this work for using nylon lock nuts that can hold position on the bolt with a little bit of play, to thread tape and machine oil to aid lubrication and minimise friction, I still have issues.
When I take the tracks off the motors run fine. I can even put reasonable pressure on the rear wheels and they seem to keep moving ok.
As soon as I put the track back on, it tries to move, stops and beeps… Back to that cycle.
I have re built the Raider twice and I keep hitting the same problem.
My son really wants to make the land raider work, please, any help,appreciated.
tech_support
#3
Hi Timb,
Firstly, could you please check if you have assemble the ranger with the correct wheels.
In the part list, there are 4 x 62T wheels Without Step, 2 x 62T Wheel, and 2 x 90T Wheel. The 62T wheels are smaller than 90T wheels. The wheels on Ranger should all use the 62T. Kindly check if you have used the 92T wheel by mistake.
I
If the wheels assembled on ranger are corret but the tracks are still very tight, please kindly send email to tec-support@makeblock.com with the receipt.
Timb
#4
Yes, I have double checked and I have the correct wheels (smaller ones) in the correct placement.
I have tried everything to adjust and trouble shoot the tension on the tracks to no avail. I am now thinking, potentially that the power supply might be the problem. Would you get the same result if the voltage drops too low? I am considering getting a 7.3v l-ion battery pack and seeing if this fixes the problem.
tech_support
#5
Hi Timb,
Yes, normally, the ranger will function abnormal or hard to drive when it cannot get enough power.
It is great to try the 7.4v Lion battery and see what happens first.
Timb
#6
I could not find any L-ion battery packs with suitable plug for the board. I will keep looking as I think this may be ideal ? But Instead for now I bought some high quality 2500mah NiMC AA batteries and it is now working. Excellent!! Thankyou. Very happy child!
RobLac
#7
I have the same issue. The tension, stiffness, and overall design of the track is poor. The track won’t turn, even with brand new Duracell batteries. I wrote a review on Amazon and they sent me here…
I took the track off and put the rubber tires on the wheels instead to make sure the track design is the problem ,and sure enough… something tells me the manufacturer is not QAing the materials used for the tracks.
Timb
#8
Hi Rob, check my responses . The standard type of batteries will not power the ranger. I found the ‘power loss’ curve of standard batteries starts as soon as it’s used , i.e., within minutes it’s only pushing out 95% of its power, and constantly reduces. Once the power is below a certain level, it will stop as the CPU will measure the current and decide not to respond to commands. And it happens pretty quick. NiMH batteries are made to hold maximum output for most of the battery life, then drops off sharply at the end… Hence, you will need to use good value batteries. NIMH or LIon batteries. We havent had any problems since getting the proper power to it.
mtaylor
#9
I’ve been running into similar problems with my new Rangers. I think the problem also relates to the design of the driven wheels. If they are bolted in tightly enough to stay put, they put excess friction on the wheels and are difficult to drive. If they are attached loosely enough to spin freely, the nut works it way loose very quickly. Seems to just be poorly designed. I’m trying to figure out alternate mounting options, or a way to fit a different wheel.
tech_support
#10
Hi Mtaylor,
Could you please kindly take a video to show the bahave on the ranger when you test it with the nut is screwed tight and screwed loose.
Please kindly send the video to tec-support@makeblock.com.
Since the spring festival is coming, we may double check it when back to the office, thanks!
chadman
#11
The wheels bind, if assembled according to the instructions.
To solve the problem, I replaced the nylon spacers with 3 extra nuts. There were plenty provided. Screw the first nut close to the wheel while still allowing it to turn. Tighten a second nut against it so neither move. Make sure the wheel still spins freely. Add one more nut. Put the wheel assembly though the frame hole, and secure tightly with a final nut. Repeat for all 4 front wheels, then replace the treads. So far, it works great.
bobfields
#12
chadman. You are a genius! I had the same problem and this fixed it instantly. I put brand new batteries in my ranger and they only lasted a 1/2 hour at the most, not acceptable at all. I put another 6 new batteries in after your fix. The ranger now moves way faster. Hopefully we’ll get a bit more play time out it too. Thanks!
martinabel
#13
Hi all, thanks for the thread. Same problem here. Seems to be a batch QC issue. I’ve tried the nuts instead of spacers, but it’s too much of a hack. On closer inspection after comparing one wheel that moves freely, and another that sticks, I can see there are two issues with the parts:
- The brass coloured spacers should just fall into the hole on the black wheel. If they need pushing in, then the hole on the wheel is too small - I used a small round file to wear the hole bigger… not ideal, but works. They should have been machined accurately during manufacture
- Either the black plastic wheel or the brass coloured spacers are the incorrect depth. When two spacers are pressed together on either side of the wheel, then there should be a tiny gap on the outside edges so the wheel moves freely. Mine doesn’t. - solution is to put a tiny washer between them inside. Again
I hope that helps folk. The other thing to do is reduce the tension on the belts by moving the wheels to different holes, but you’ll probaby get more give in the rubber simply by stretching by hand before putting on. Hope that helps. Afraid, not that impressed that I have to make these modifications. New wheels that are correctly machined would be ideal.
martinabel
#14
Last entry. All working fine now with those modifications. Bit squeaky so will need to buy some modelling oil! The final thing that definitely needs changing in the instructions is the position of the main drive wheels. The suggestion earlier was an excellent one. The drive wheels need to be one hole closer to the smaller wheels compared to the instructions, otherwise the tracks are much too tight and it really struggles to move. Hope that helps if anyone finds this thread. Now it’s working, am very pleased. Will need to purchase another 10 for my tech clubs. Hope they don’t all need the extra wheel mods! 
Timb
#15
Hi Martin, i know i started this thread about wheel tension, however not sure if you saw my last comment about the power supply ? As the wheel tension actually had nothing to do with the issues i was having.
I now have 2 of these (one for my younger child now aswell) and both are built as design and working perfectly. We reconstructed the same scenario on the 2nd one bought a year later than the first, with the same results.
Standard batteries are not up to the task. I’m running them with good quality NiMh batteries without any problems at all, and with no deviation from the original design / construction plan.
Cheers, Tim
martinabel
#16
Big thanks Timb,
That’s great. Yes, the power thing I noticed too. Trying to use standard household batteries didn’t work at all as you say. However, even after I changed to powerful NiMh rechargeables, the mBot Ranger still struggled big time. With the standard setup, those wheels were REALLY stiff, i.e. not correct. I think I must have received the ‘unlucky’ one. After making those changes:
- rubbing the wheel hole so the brass coloured spacers fall in/out = nice fit but loose
- adding a tiny washer between them inside the wheel so they don’t bind on the outside edge
- moving the belt drive wheels one hole towards the smaller wheels
- adding some oil to spindles
All went lightning fast!
Very pleased with it now. My only challenge is now to find the ‘100’s of open source projects’ available online. Not sure where those are… still looking
grushka
#17
I also just bought the ranger for my son, and it does not drive well at all. Tracks too tight I believe, and too much friction.
Very disappointing 300$ AUD gift! My son is a “battle-bots” fanatic and he was asking for a robot for months…
Does anyone know if there are ball-bearings that can fit/replace the gold/copper bushes?
Makebloc - you should consider shipping your robots with ball-bearings!
I also noticed that people mentioned NiMh batteries? The instructions specifically note Alkeline (which was a bit odd for me) anyone experience any issues with using rechargeable NiMh?
tech_support
#18
Hi grushka,
Sorry to hear that!
Here we assembled a Ranger according to the User manual, the track isn’t too tight and easy to move it.
I want to double check some points to make sure if you have assembled it correctly.
- the 6 wheels for the ranger are all in the same size. Please don’t use the larger wheel (92T wheel) by mistake.
- Please make sure the wheels , motors are assembled to the correct holes according to the user manual.
- When assemble the track to the wheels, please make sure the wheels go into the slots on the tracks. After assembled it, please rotate the tracks several times by hand and see if it still too tight.
As for the battery, you can use the alkaline battery with good quality like Energizer, DURACELL.But the Ranger is a high power robot which need high power during its operation so that it can easily consume the power in the battery.
In this case, it is better to use the rechargeable lithium battery.
Motors not working. HELP!
martinabel
#19
Hi Tech support,
Awesome help !
No wonder. I was using the big wheels at the back… derrr.
However, just purchased 10x mBot Rangers and without exception the bras bearings/bushes are too tight in the wheels for the front four wheels on every one of those kits. I’ve had to use a small file to take some of the plastic off the inside so those brass fittings actually fall out smoothly when the wheel is tipped, i.e. they don’t bind. I’ve also added a tiny washer between them inside the wheels so they don’t bind on the outside edge either and a bit of oil. Those rangers are now very fast and smooth. I still think the manufacturing needs sorting for the front wheels. When tightening as per instructions, they are way too stiff. Hope that helps. Really ace piece of kit! Martin
tech_support
#20
Hi Martinabel,
Glad to hear that it helps.
As for the part you mentioned, we will keep checking, thanks for your feedback.