Tired Of Breaking Fan Blades? Try This...

[Mr.Duke]

For the last year or so, I’ve been experimenting with ways to resolve the issue of breaking fan blades in the ESC, whether it’s the BLX 185 or HW Max6.
What I’ve found is that on some hard impacts the tips of the blades will make contact with the underside of the guard above the fan. This seems to be much more of an issue with the Max6 but it applies to both.
This leads to the tips being chipped and eventually breaking the blade itself where it connects closer to the center of the fan.

I went from breaking fan blades about every 3rd pack to only breaking 2 in the last 8 months. I’ve had a couple other fans fail but that was due to the wires coming loose at the fan itself.


There are 2 modifications that I make that in conjunction has helped the fans live much longer.

The 1st...
Take a small square of fiberglass screening, same as what’s on a window screen or a screened in porch, and cut 4 holes for the screws to poke through.

This adds a soft but somewhat effective barrier between the fan blades and the housing above.
This can improve the life without modifying the fan blade itself, but I’ve found that doing both work very well together.

2nd - Clipping the Tips and Profiling
This may look like a pain but it’s really not.
What it accomplishes is that in the event the blade does come into contact with the fan guard, the revised profile keeps from breaking the blade off

First take a small pair of side cutters and clip the tip off an a triangle pattern on the side of the fan that faces up. Try to be as consistent as possible when removing any material as it can produce a slight imbalance if one weighs significantly more or less than the others.

take a small file and profile the leading edge of the blade so that it’s round

Do the same on each fan blade.

New fan on the left, modified one on the right

Hopefully others will find this helpful in extending the life of their ESC fans.

 

[SrC]

I like that idea. We all eat those fans.

 

[Mr.Duke]

I forgot that I made this video back in May of last year when I started testing out ways to keep from eating fans in the Max6.

@bicketybam and I were brainstorming as he had similar issues with eating fans.
This video was to better explain what my theory was at the time behind the breakages and what I thought could be done to mitigate the issue.

You’ll have to forgive the language as it was late and I’d been sipping on a little ?. Never intending for it to be part of a future thread, but I feel like it gives some useful information in it.

I ended up testing more durable screening over spring before realizing that if I’d reprofile the blades themselves it would help solve the problem.

I feel like it’s been tested enough to recommend the fix to the rest of the forum.
If anyone wants to give it a try, let us know the results

 

[SrC]

Fans with alum. frames will also probably solve the problem. I haven't tried the above yet. Surely will.
Using a fan grill helps a lot also if just placed on top of the esc. I felt that rocks and debris was also chipping cracking fan blades. Because I always find twigs and small stones in the blades and stuck in the ESC heatsink when they broke.

 

[magnetik]

You can also use paint strainers (like the ones you line 5gal buckets with) for a cheap filter. They are also finer and will filter smaller debris better.

 

[Mr.Duke]

For this application it’s not so much about it being a filter as it is about creating a barrier to help keep the tips of the blades from hitting the bottom of the fan guard and breaking off.
You have to be carful with how small the holes are for the screening you use as it reduces airflow to cool the ESC

 

[SrC]

For this application it’s not so much about it being a filter as it is about creating a barrier to help keep the tips of the blades from hitting the bottom of the fan guard and breaking off.
You have to be carful with how small the holes are for the screening you use as it reduces airflow to cool the ESC

Agree about size of screening. That can go against you. running hotter. I find that proper spacing of fans to the HS or hot surface makes a huge difference also. An Aluminum framed fan reduces broken blades greatly. Use a grille in addition and the blades last a long time.
BTW, I find that Ball raced fans don't last longer. They tend to spin at higher revs, but fail sooner than cheaper bushing fans. At least in RC environments, that is.

 

[Mr.Duke]

I agree about the aluminum fan frames being more durable and those are what I run on all of my motor fan assemblies. I’m not aware of anyone that makes 35mm aluminum fans that fit the BLX185 and Max6 though. The only ESC fan breakages I experienced are blades snapping off or one of the wires pulling out of where it connects at the base of the fan itself.
As far a spacing goes, both the BLX185 and Max6 have the fan spacing right in the sweet spot and do not need to be relocated to provide efficient cooling.

 

[SrC]

Agree, blx185 fan is pretty
much where it should be. I removed the plastic venting fins of the shroud at the sides which are not needed. The HS is exposed better for thermal exchange. I use liquid elec. tape at the wires leading to the fan for strain relief. They do come apart eventually. These rigs go through hell and back. Details matter. ?

 

[mpspringer]

Would the HobbyStar Turbo-Ventilator Aluminum ESC/Motor Fan work as a replacement fan? Really like this idea and will try it on the OEM blades. Thanks!.

 

[jkflow]

Would the HobbyStar Turbo-Ventilator Aluminum ESC/Motor Fan work as a replacement fan? Really like this idea and will try it on the OEM blades. Thanks!.

No, not as a drop in solution. It's a 30mm fan and BLX/Max6 use 35mm fans.

 

[mpspringer]

No, not as a drop in solution. It's a 30mm fan and BLX/Max6 use 35mm fans.

thank you for confirming.
ive broken 3 fans in the last month. nothing too crazy either.. just on grass and cement. im going to try this solution.

 

[Mr.Duke]

Would love some feedback from others that have clipped the tips on how the fans are holding up after modifications.

 

[Hammer Down]

Would love some feedback from others that have clipped the tips on how the fans are holding up after modifications.

I’ve had huge success with this method!!
About a dozen HARD! sessions and haven’t broken a blade since. ?
Before doing this I couldn’t get thu a pack without breaking multiple blades. ?

 

[Mr.Duke]

Moooooore feedback please.

 

[robert@castle]

We are seeing similar issues on the Monster X 8s and came to a similar conclusion. The fan spins fine normally but is able to move more vertically than we anticipated while running due to vibrations in the chassis. We are applying a rolling change to the case to give slightly more room for the fan to move.

We do not recommend cutting the tips of the blades as that can either unbalance the fan or reduce it's airflow output. Thankfully it is simple to fix on the Monster X 8s since the blade guard is a separate piece from the top of the case. We recommend unscrewing the fan and placing a washer or spacer between the fan and the blade guard. This will keep the blades from contacting the blade guard without impacting airflow.

 

[Yas]

Will be trying this on a new fan for my brand new Max6 combo. On the 3rd run when checking temps I noticed the fan had stopped and a blade had caught on the guard above it

After poking it back down I later checked it, only to find the fan had stopped again; one blade had already broken off and another was caught ?

 

[Yas]

?

 

[Hammer Down]

?

View attachment 83909

You forgot the window screen...
That’s a key piece I believe.

 

[Hammer Down]

We are seeing similar issues on the Monster X 8s and came to a similar conclusion. The fan spins fine normally but is able to move more vertically than we anticipated while running due to vibrations in the chassis. We are applying a rolling change to the case to give slightly more room for the fan to move.

We do not recommend cutting the tips of the blades as that can either unbalance the fan or reduce it's airflow output. Thankfully it is simple to fix on the Monster X 8s since the blade guard is a separate piece from the top of the case. We recommend unscrewing the fan and placing a washer or spacer between the fan and the blade guard. This will keep the blades from contacting the blade guard without impacting airflow.

Here’s my MMX8s fan from the K8S after one good bash session.

I hope you guys are refining this design...

Also when will they be available on the castle website??