Efoil build using drill gearbox


what do you think about this one: https://www.youtube.com/watch?v=19-PgJveCyg

this is its corresponding gearbox: https://www.aliexpress.com/store/product/Genuine-Gear-Box-For-Makita-123953-7-DHP484/1972135_32855038178.html?spm=2114.search0104.3.291.32296553yJaGXd&ws_ab_test=searchweb0_0,searchweb201602_3_10152_10151_10065_10344_10068_10342_10343_10059_10340_10341_10696_100031_10084_10083_10103_10618_10624_10307_10623_10622_10621_10620,searchweb201603_12,ppcSwitch_5&algo_expid=3df362d4-2bbe-40f0-8518-73a819db0048-46&algo_pvid=3df362d4-2bbe-40f0-8518-73a819db0048&priceBeautifyAB=0

up to 2000rmp though but might be ok going on to 3500-4000rpm. In terms of torque and power looks quite good for us


I usually start from current offer (search engine), for numbers and sturdiness MAKITA 2013, DEWALT 2014, MAKITA 2017 and MAKITA 2018 guides allowed me to spot the metal gear versions. My enthusiasm was cooled down with a few “How to replace” Youtube videos showing many Makita with so called “metal gears” having a plastic -R-ing gear (red below) so not 100% metal gear for best possible life time. Finally, as rotating in water isn’t as difficult as in a solid material like steel or concrete that creates a lot of wear on planet gears, the problem is now to determine/find/(modify?) the reduction gear to suit the propeller we have or ask to guys like @Flying_Rodeo to design us a propeller according to the reduction gear that offers the best quality/price ratio. If many people are interested, ity’s a win-win if the produced quantities are high.


According to you @MaB , what would be a good potential candidate ?

@Antonbit : 50USD for a genuine model is quite good. In the 2017 guide above the Makita DHP484 Brushless 18v is described as a general duty so the beginning of sturdiness (inferior to Heavy Duty range 458 and 481 see below)

The brushless DHP484 is the newer general duty option from Makita. The gear housing is upgraded to all aluminium giving it a distinctive sturdier look whilst making it the lightest drill in our comparison. A brushless motor and metal gears mean the DHP 484 will outlast lesser options. Slightly reduced torque numbers are the price paid for a smaller, longer-lasting machine. The DHP 484 is the perfect choice for tradesmen who tackle a variety of daily challenges and require a long-lasting, reliable, robust option.

In the guides they say:

DHP or DDF it doesnt matter in terms of drill performance. The only difference is DHP = hammer action, DDF = no hammer action.

Meaning that non-hammer (Makita DDF) drill gearbox must be favoured as they are more simple and hopefully more compact and cheaper.
Same process with Hilti and the other professional brands. Could be a long search. But if we can be at least 5 persons looking in different directions…

DHP 458 gearbox : 56 USD on aliexpress for a 88mN torque is well above our needs but can it cope with the 3500 rpm we need ?

Spoiled for choice on AliExpress : 22 genuine gearbox models from 25 to 67 USD all with nylon outer housing make me think that the first one you find in a junk will provide plenty of information.


We do need rather 15K rpm, on input shaft. This is or better “was” my Apex PL 50 gearbox. I thought of thrust bearing not getting the load but now I have seen the pinion gear: stripped, naked! I always used buttery smooth accelleration ramp, 2,5 sec 0 to full. Don’t know what to blame, except that such teeth are small… Maybe stop torque when close throttle at speed? Caught something with prop? I would have perceived that.
To get back to drill planetary, the main issue is replacing these thing! Adapt your pod abd almost rebuilding it at any failure. So, is it worth? I wish so, because of price and availability. To be tested


I’ve got a 1/2” Makita impact driver in the garage that I need to strip down. I will do it later and post some photos.


I decided against the apex PEII 50 because of the max RPM of 8000 listed in the specs. It also doesnt look easy to get heat away from the gearbox because of the shape. Im surprised to only see three planet gears. If you go to the Neaugart ple40 youll get 4 planets, 18000 rpm with cooling, and hopefully a longer life. Thanks for putting up the photos.

It will be great if something comes out of these drill gearbox ides.


Stripped down the DTW450 impact wrench and this is what I’ve found …

It’s very well made but I’m not sure it would stand up to the RPM required. Overall diameter is about 68mm.


I guess an easy solution would just be to make the gears twice as high, so they have more contact surface and half the load acting on the pinion.


Im using these.

Had a second hand drill I stripped down but you can still buy them new.
fusion files


On paper was not bad… Flying Rodeo use or used these, I don’t know how it get wasted so bad in 3 hours of riding. 360kv SSS is quite a bad ass motor, with my latest prop you could feel the thrust and the board speeding as hell even with my kid on top (obviously not foiling…for safety!), but unless I got something on the propeller without noticing, this gearbox just did not hold the torque, period.
The weird was that I took a 45 minutes run, after few minutes the board start to become noisy, like resonating. I kept foiling at moderate speed and master the “zero” and “8” figures foiling, lot of fun! Then I crashed and when got back on the board… awfull sound and motor stuck! I did not insisted with throttle and paddled back to shore. That’s what the noise was: gears stuck somewhat.


What your saying makes me think it is related to excess heat in the gearbox, even more now.
I think it probably lost a tooth when it started resonating and destroyed itself from there. I think if the damage was gradual over the first three hours, you would of noticed it. I wonder, if you filled the void between the gearbox and the housing with thermal grease, maybe that would get the heat out well enough. Are you going to try another PEII 50?


I had an aluminum tube to fit perfectly the gap gearbox/tube, with thermal grease around… maybe was not enough.
No more Apex, I have not found one available soon. I have a Neugart now. That probably have even more cooling issues, because of the smaller diameter…40mm vs 56 of the tube. But many peoples use it without issues


Got the foil sorted sit is able to be unplugged and removed. Just need to get the rest. Of the wiring sorted now.


Any one has thinck about this gear box :

Seems good in term of size of proppler?


Hi gobbla,
actually this angled transmission could be used to place a larger and shorter diameter motor with lower KV inside the board. I never thought of this before. Perhaps the transmission shaft is thin enough to run trough the mast.
This will have several advantages:

  • not need for connecting connecting/disconnecting cables every time you remove the mast
  • you can keep the motor in a dry environment in the board
  • possible to choose from a wide variaty of motors with big diameters(more torque)

Maybe something for version 2 :slight_smile:


I imagine there would be a fair amount of loss in that right angle drive, plus, the motor would have to be mounted vertically unless you used another bevel drive at the top. It would be far easier from the point of view of wiring and sealing though.


Its true that a spiral bevel gear has a slightly worse efficiency(95% for lower ratios, especially Chinese ones :wink: ) compared to a planetary one (±97%).

Why would you need to place the motor horizontally? I see a vertical motor placement as an advantage:
-Able to use a shorter, wider motor(lower kv=no reduction needed=higher efficiency)
-able to to place in a strong concealed box(think aluminium junction box) inside the board


I was just thinking of the height of the motor plus coupling might be difficult to incorporate into the thickness of the board.


I think this could be an exceptional ideal! Would mean less under water, easier to seal and in the board we could run a motor and an angled gearbox. What are everyone elses thoughts on this?


This looks like option 11 here: Propulsion Type Overview - Wiki. It’s been done and it works. Noise and vibration were the biggest complains, unpleasant to ride compared to the more quiet under water solutions. Also cooling is harder but that can be solved.


First water test no foiling but moving and nothing blew up. Whoop woop