Relative power of different drive trains in comparison to each other

As in the title, I was wondering if a few of you would be able to put up some fractions or something with regards to how powerful the common drive trains are to each other. This would be for a 2wd pusher along the lines of Endevour, Tiny Toon etc. So my holy grail drive train is Speed 900 on a single stage reduction. How powerful in comparison to this in the real world are (i.e. 1/4 as powerful, half as powerful, twice etc.):

£10 drill motors
Speed 600's
Gimson 18v
Torpedo 800's
Dewalt 18v
Makita's
Torpedo 850's

and so on.

you want reliability as well, the cheap argos don't seem to last long, endevour uses 2 speed makita's on 14.4v i believe which are the same version as im going to use in Night fury 2, so on a 4s lipo with 100mm wheels should be able to do 15mph and have twice the power of the old drills, its predecessor used 12v ryobi drill which are still intact after 2 years of abuse and no maintenance but the motors did start to come loose from the gearboxes but they were easily tightened as far as the other motors i will have to leave that to others as i haven't used them

Perhaps the title should be 'How effective are these motors'. Just knowing what their power output is, is only part of a much more complicated equation: you will also need to factor in the voltage, gearing, tire coefficient of friction, speed and more. All that stuff is hard to work out, so I use these two resources:

http://architeuthis-dux.org/torquecalc.asp

http://www.enigmaindustries.com/EDTSim.htm

You can find extra motor specifications via Google or substitute generic motors from Johnson or Mabuchi for various drills. Past a certain point, it doesn't matter how powerful the motors are. Once the wheels break traction and spin, any extra power the motor might be able to produce is mostly (see below) irrelevant.

When looking at motor power output, most manufacturers quote the peak output in watts but fail to mention how long the motor can sustain that before overheating and failing. A larger motor with more power than you need provides a safety factor that makes it more reliable.

Out of that list, the Dewalt 18V is easily the most most powerful at 1,100 watts and the heavy construction and efficient fan means it can put out that peak power for longer than other motors. If I was going to design a pushy bot, I'd go with 18V new series Dewalts and the Dewut mounting kit; its a good balance of power, weight and reliability. Add some really grippy wheels and you have a a contender :)

That's cool, thanks for the guidance :) Is it true that the DeWalt motors fall apart if you take them out of the casings, and if so do you know a way round this? I've always known that Wattage is the power rating of the motor but I always wondered is this was literally an accurate guide of a motors power in the real world, after efficiency comes into it and so on.

I will have a look at those links :)

As Nick said if you have enough torque to break traction then next for me is reliability. I've got through endless drill motors and dont want to spend half the time at an event replacing motors.
I have a speed 900 powered pusher lifter. Apart from its appetite for batteries I don't have too many worries with that. No chance of replacement motors though.
I have some Dewuts for lifters and they are nice but heavy units.
I'm watching how the Aussies get on with brushless http://robowars.org/forum/viewtopic....asc&start=5565

robot market place have some nice dewalt kits. The US have been modding and using those motors for years.

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Originally Posted by daveimi

Is it true that the DeWalt motors fall apart if you take them out of the casings, and if so do you know a way round this?

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I am not sure what you mean by that - do you mean taking them out of the plastic drill shells? I wouldn't be surprised if the motor and gearbox separated when the drill is taken apart, but the motors are one self-contained unit and definitely don't come apart. There are some other DeWalt drills that have 'frameless' motors, which would probably fall apart when the drill is disassembled; these aren't the droids you're looking for :). I would recommend getting the motors & gearboxes on-line from the RMP or somewhere similar.

@ Chris: not long to go for the testing - I just took a break from mounting the gearboxes and electronics.

Yeah I mean do you know if anyone sells a kit or something. I suppose you could just leave them in the casings and pull the chuck off to mount your wheels.

Yes... Charles Guan has a DeWalt mounting kit for sale:
http://e0designs.com/products/dewut-...gearmotor-kit/

Like Gary said, Robot Marketplace sells the motor, gearbox and the mounting kit: http://www.robotcombat.com/products/0-DEWUT.html You might be able to get the motor & gearbox cheaper by buying a 'skin only' drill on Amazon or eBay, but I don't know what model you would need.

This is just one of the better options, there are plenty of others out there.

Dewuts are a great solution and allow you to use any of the 3 speeds in the new dewalt gearboxes with a quick change of the selector bar. I've been running these for around a year now and have had zero issues with them. I sourced my Dewat kits directly from Charles @ e0designs and then bought the motors and gearboxes off eBay for US$30-40ea (There is a refurb place on eBay that does them).

The only negative of a Dewat kit is that they are a fairly big unit, being 63.5mm square and 200mm long, which might make them a bit bulky for some designs.

I was planning on trying to design up a metric DEWUT kit, unfortunately the CNC machines I have access to can only machine plastic so I was going to trial it with Delrin.

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Originally Posted by Pinski1

I was planning on trying to design up a metric DEWUT kit, unfortunately the CNC machines I have access to can only machine plastic so I was going to trial it with Delrin.

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I'd be keen to collaborate with you on that. I've got some old polycarb we could try too. I don't know how well it will machine or how tough it will be, but it might be useful whilst we tune the design.
I noticed Charles has released the IGES/Parasolid files for the Dewut kit, so it shouldn't be too difficult to get started. From a quick look through the files the smallest feature I've found needs a 2mm cutter, and I've got a bunch of those suitable for the CNC router.

My main reason for a redesign was that I need to learn how to use proper CAD software not SketchUp which is only just working for me currently. I wanted to make quote a few edits, my dewalt gearboxes seem to be different to Charles' and I wasn't happy with the clamp motor mount.

Unfortunately the hardest part to fix will be the funky shaft , I had the idea of using a shoulder bolt that has the head cut down but you'd need a shoulder greater than 20mm to get a large enough head.

(I'm on the phone, excuse the rampant spelling mistakes)

Starting with an off-the-shelf screw is a great idea. I think an M16 cap head would just about do it, or a '16mm' (M12) shoulder bolt. The head wouldn't be as large as the Dewut one, but it should still sufficient to engage with the 'nubs'. Lets chat offline.

"nubs"? Do you mean shaft splines? If so, for any kind of reliable drive, you need to have a spline on the shaft to engage the gearbox. A fudged solution will work for only so long.

The output carrier has both 'nubs' and an internal spline:
http://www.etotheipiplusone.net/pics...dw/dewut25.jpg
The 'nubs' originally interacted with an anti-backdrive' system:
http://www.etotheipiplusone.net/pics...dw/dewut24.jpg
But Charles used them to drive the output shaft:
http://www.etotheipiplusone.net/pics...dw/dewut29.jpg

An M16 screw head is large enough to have cut outs machined into it to engage with the nubs, but would have a little less engagement.

How would 4x 12V drills compare to say 2x Makita's or Dewalts? Beginning to think the easiest way to more power would simply be 4WD drill pusher.

Generic drill motors are rated about 100W peak power while 18V Dewalt motors have 1100W peak power. To get the Dewalts pushing efficiently, you will need some very wide & grippy wheels.

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Originally Posted by overkill

To get the Dewalts pushing efficiently, you will need some very wide & grippy wheels.

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I found wide wheels to be an issue with my Dewalts. Running 4"x2" colsons have too much surface area for the weight of robot and just allowed excessive wheel spin. I'm currently looking at stepping down to 1" wide wheels to up the weight per mm on the tread. Probably not an issue if the robot was a LW however.

I never heard that before, thought you were happy with those wheels. Do you think a softer tread would have worked better?

I love the wheels, but I just do not have the weight to utilise the available potential. Annoying Box Rush's fight against Plastic Fantastic showed it evidently as PF's drill motors with two 100x20mm Anderson wheels was able to stale mate ABR with Dewalts and four 4"x2" Colsons when in a pushing match (ABR just had wheel spin at anything over 1/4 throttle).

To add a bit to the Dewalt/Wut discussion, I've been using the older style Dewalts in my 30's for quite a long time. (Moros, Nyx, and Spanky) The DeWut seems to be a really good replacement for the older Dewalt and the bots that are running them seem to move pretty well.

Here's a few matches from Motorama with bots running DeWuts-
https://www.youtube.com/watch?v=UYFMMGfviO8 (MegatRON, 2wd overhead saw)
https://www.youtube.com/watch?v=8J9fuvAswQI (MegatRON, 2wd overhead saw)
https://www.youtube.com/watch?v=hjSkzD26W4E (MegatRON, 2wd overhead saw)
https://www.youtube.com/watch?v=ODVCgQCR0vI
(Nyx is mine, green and black, Blitz was running 4 DeWuts, probably mid gear with these wheels: http://robotcombat.com/products/0-YAK3.html )
https://www.youtube.com/results?sear...locker+Advance (Clocker uses 2 DeWuts for drive, 1 for the weapon)

I'm personally a big fan of the Colsons, to the point that I'm actually doing a small production batch of hubs for a 1/2" keyed shaft that will fit the 1.5" wide Colsons (which is what Nyx uses and Nyx2 will use) They'll fit 2" wide as well, but there will be a gap on one side as the hubs fit flush with the 1.5" wide wheels.

Aaron: do you turn the Colson's surface flat? I find that skimming the wheel on my lathe exposes slightly softer plastic which gives a bit better grip. Its not a huge difference but worth doing IMHO. I agree the 1" wheels are the right way to go. Along those lines, can your forthcoming BotBitz wheels get a softer tread than the Colsons?

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Originally Posted by overkill

Aaron: do you turn the Colson's surface flat? I find that skimming the wheel on my lathe exposes slightly softer plastic which gives a bit better grip. Its not a huge difference but worth doing IMHO. I agree the 1" wheels are the right way to go. Along those lines, can your forthcoming BotBitz wheels get a softer tread than the Colsons?

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I don't turn the wheels down, but I do drive the robots on rough concrete to wear that initial few layers off, which also allows the wheels to wear to suit the robots particular stance. The forthcoming BotBitz wheels are going to be 50A compound, which is the same as the blue Banebots wheels (Which I personally liked), which is a bit softer then the Colsons which are ~60A.

Would I be mistaken in thinking the motors in these were similar in power to the dewalts from robot marketplace?
http://www.ebay.co.uk/itm/PARTS-ONLY...item5d50828d1e

I think I have said this before somewhere,

"It's not the power of the transmission it's the power you can transfer to the arena surface".

There are lots of very powerful transmissions in the featherweight arena I have been up against, and I have pushed all of them around with E-Knock AKA Tron. and that runs on 4 drill motors 12v, powered with one 3s 2200mAh battery. wheels standard blue type with bike tyres screwed to them!

The only way to get even better traction is to use some sort of ground effect to increase the attractive force between the friction surfaces!

I would go for 4 drill motors. like E-Knock
have a floating blade on the front. like E-Knock
make it invertible. like E-Knock
and have some fun like ME-EEEE.

Thanks for the advice, it's good to know 4 cheap drills on 12v would do fine. None the less, I'm aware that even though you can't put down all the available power with more powerful motors, it does make a difference and certainly won't make it worse :)

Nick mentioned earlier that he thought a pair of DeWalts on 18v would create a good pushy bot and I was wondering if I'd found a way around paying $200 and postage from America.

I've ran Spur and Spur II
Spur had 4 drill motors with 100mm x 25mm wheels with a grippy mountain bike tyre screwed on
Spur II had 4 Gimsons with 100mm x 20mm wheels with a grippy mountain bike tyre screwed on

I would say Spur II was the better drive. The loading on the Gimsons though killed motors easily.

I have a couple of DeWuts as well and they are certainly very nice

After all my experimentation I can second 4 x drill motors. 2 x drill motors will shove a 10kg bar bell weight around my drive. A lot of the pushy robots have batteries over the axles and focus on lifting an opponents wheels up to break traction.

I've built a featherweight before with 2x drill motors, was a bit slow though, although traction was decent.
Back to my original questions though... are these equivelent to the DeWalt's mentioned earlier in the thread?
http://www.ebay.co.uk/itm/PARTS-ONLY...item5d50828d1e

This seller says the motor is for a DW997 similar to what is for sale so the answer is probably yes.

I would check with DeWalt tech first.

http://www.ebay.co.uk/itm/DeWalt-18-...item53fab3a1f2

Cool, cheers for the advice. Just scouting around for bits and bobs in prep for when I get introduced to the uni student workshop ;)

All you need is a good hammer and a kitchen step :)

Not sure how my flatmates would feel about the banging and destruction of the kitchen step though :P

Lol i suppose so.