[WIP] 18 Volt Drill Master LEGO conversion

[Boxerlego]

18 Volt Drill Master LEGO conversion

[WIP]

BY Boxerlego

Table of contents

Introduction

Introduction

Hi, This is my latest LEGO custom motor project but its not the only one I'm working on I just bought this 18v drill today for the intention of modifying it for LEGO use. My previous drill motor project I only modify an old 18V drill motor to fit with LEGO but this time around I've a new 18V drill motor with a fresh 18 volt battery pack and I'm going to try to fit with LEGO. The nice thing about this is I got that power drill with an 18v battery pack along with charger for a great deal of $16, the original sale price was $35. My first 18v drill motor project had tons of problems to over come and for a long time at first the motor was not even able to be power with LEGO 9V PF system. This was a major problem for me and ultimately I didn't quite know enough on how to drive a DC motors with electronics. So I moved on to my next motor project which was a stepper motor and was more efficient that it could be driven with the LEGO V1 PF system. This was a good step up but it wasn't quite as powerful as the drill motor can be. It didn't take long for me to figure out how to drive a motor with electronics, there are lots of good YouTube videos out there that got me started but ultimately how to properly drive this 18v drill motor with LEGO was still far from perfect. My first motor driver had several mistakes however LEGO was able to still make it work but still those problems needed to be understood and corrected so I can make improvements and make it work better.

I will spare all the details here and I will just say that in 2014 I learned tons about how to properly drive motors and more efficiently. Which brings me to my other motor project the upgraded XL motor I'm working on, which is reaching the final stages and that is building the motor driver. This motor driver here for the XL motor MOD is absolutely the best one I made yet. You wont believe what I was able to with this motor driver or maybe you will . I will just say that this motor driver here I made works from the regular 7-9 volts the LEGO Battery box can supply but however the XL motor mod has a switching DC power supply that can step up the 7-9 volts from the battery box to 12 volts for this XL motor mod to work off of.

Overall this topic will mainly be about the 18v drill motor LEGO conversion so to start it off I want to show a video time line of some my previous projects with my first drill motor.

Video Time Line

Think this is either going to work or not please feel free to comment on the matter. I hope everything works out well

[nerdsforprez]

I know many are against modifying stuff (lego) but not me. I think its great to try and improve propulsion for our Lego models. Great job on this one!

[__________________________]

Looks great! Also, what's the easiest way to increase voltage, using only PF parts?

[Boxerlego]

I know many are against modifying stuff (lego) but not me. I think its great to try and improve propulsion for our Lego models. Great job on this one!

Thanks, I have high hopes for this motor project. There was a previous drill motor that was given to me but that motor was a little to big to fit in between the 1x7 liftarm spacing which the XL motor is design to fit in between. That motor was huge but that motor was an somewhat expensive 1/2 drill. I'm hoping here that this 3/8 drill motor is small enough to work out how my first drill motor did.

Looks great! Also, what's the easiest way to increase voltage, using only PF parts?

Thanks, The easiest way to increase voltage is to add another battery pack in series. Doing this can increase voltage up to 14-18 volts but this depend on how strong the batteries are. I made a thread about this battery connection ( http://www.eurobricks.com/forum/index.php?showtopic=77490 )

[Corvette3]

Don't forget, alkaline batteries actually drop voltage under load, in any kind of normal use, they actually give about 1.2-1.3V depending on how much current is being used but a NIMH gives 1.2 much more strongly, so its not going to be 18 volts with 12 AA Alkalines.

[Boxerlego]

Don't forget, alkaline batteries actually drop voltage under load, in any kind of normal use, they actually give about 1.2-1.3V depending on how much current is being used but a NIMH gives 1.2 much more strongly, so its not going to be 18 volts with 12 AA Alkalines.

Thanks for that bit of knowledge. Your right about that alkaline batteries not being as strong. I have already experience that in my own way but I never really concluded it to the alkaline batteries but more to the inefficiency of the motor driver circuit I built. You can see I used alkaline batteries in my video with my monster truck. Well I would check the voltage in those batteries along with the voltage begin supplied to the motor by the motor driver and there was about 3-5 volts of voltage loss between the two and that is not good but it was good enough for me at the time. This missing volts was the real driving force that forced me to figure out how to make the motor driver more efficient.

The Dismantlement

I have dismantle the drill to see if the motor is able to be fitted with LEGO. The dismantling was very easy with this drill.

Below is a picture of the battery plugs and variable speed trigger. I'm going to keep everything on this drill to see if I can potentially use down the road with the Motor conversion in some way. I certainly need to keep the battery plug but the variable speed trigger will be a tough one to figure out in a RC setup.

Here is a side by side picture of both my 18v Drill motors. Both motors are practically identical which is awesome because that means this motor LEGO conversion will work. Sweet!

Now I have two routes I can try going at building this motor. I have already been down one which is a direct axle connection with motor drive shaft with a axle connector on my first drill motor. The second route is keeping the planetary gear box that is with the drill and some how use that in conjunction with the build as well. I have know idea if the is even possible, However, 900 rpm sounds great but here is the deal doing this will make the motor longer then a 1x15 Technic beam. With the previous drill motor I used a 1x11 Technic beam for the motor.

Edited May 3, 2015 by Boxerlego

[Corvette3]

If an XL motor can shatter gears and twist axles, then i'd hate to see what a high-torque drill motor could do.

[Boxerlego]

The Planetary Gearbox

Here is an inside look at some of the Planetary gearbox. Little like LEGO planetary gearbox except that all the gears are Metal here. The big difference is that with the LEGO one, the planetary ring gear is directly connected with the motor so the motor has one constant power output, however with the Drill planetary ring gear, it is held down by friction created by an adjustable spring clutch pack. Removing the Spring clutch pack from the drill will remove all power flow out from the motor drive shaft and the ring gear will now need to be held in place by some other means.

Here is the pinion gear for the motor. Interesting thing to make note of is the motor shaft, it is in the shape of a D instead of an O. This D shape increases the difficulty in perfectly fixing an axle connector to its motor shaft. If the motor shaft was an O shape this would have been an quick and easy conversion with the axle connector if the shaft was the right diameter. Looks like i have no choice with this one I'm going down the second route this one Now the main problem is figuring out how to connect this planetary gearbox precisely up with Lego.

[dr_spock]

Interesting. Is this going to involve more JB Weld to get a technic axle connector to the shaft?

If an XL motor can shatter gears and twist axles, then i'd hate to see what a high-torque drill motor could do.

Well, there is one way to find out...

[Boxerlego]

Interesting. Is this going to involve more JB Weld to get a technic axle connector to the shaft?

That is going to be tough to say. Right now the quick and easy way to attached the drill with LEGO is by threading an Axle into the revers threads. This works and centers the axle perfectly with out the need for JB but this will make the motor very large to mount with LEGO longer than a 1x15 Technic beam.

Close up of the threads on the axle. This axle was destine for this to happen because it was already twisted.

[Boxerlego]

Right now I don't know what to do next with the 18v drill conversion other then put the drill back together and find a 18V motor that has a O shaft instead of a D shaft. I want to use the 18v battery but as is stand now the motor with planetary is just way to big. I already have one 18V motor motor fitted with LEGO as it stands but some wire upgrading is in order for it to function with the 18V battery so it doesn't get hot.

[Boxerlego]

Now that I got the drill back together I've been doing some torque test with the axle threaded in the drill and see if I can engage the spring slip clutch on the drill. Not even on the lowest setting the drill still twist the axle to extreme limits. Turns out that the threading the axle in the drill is not really perfect after running it with the drill. I can see slight wobble with the axle and that is not good and this is due to the axle small thickness not begin the appropriate size as the screw ho after later examinations this is really due to the fact that the drill is cheap and the screw hole is not exactly centered that well...

Edited May 5, 2015 by Boxerlego