Brushless Makita mod


(Dan Nelson) #22

Which is somewhere before,”, and watch this!”.

Dan


(Vince) #23

if it makes you guys feel better I put safely glasses on just in case when first powering up.
No risk no reward


(Griff Carpenter) #24

Might be good for your next business, fabing balsa wood models. Haha :joy:


(mikep) #25

Mom on speed dial too? :slight_smile:


(Dan Nelson) #26

As far as the commutator wear, I wonder if the the “sock mod” a la @RichCournoyer would help with that? Especially since you’re loading it up and cutting without dust collection, the router could be sucking small particles through it and basically sanding the brushes/commutator. I forget where it was posted, but I remember @RichCournoyer mentioning that he had many many hours of heavy use on a single set of brushes. Maybe if I mention his name a couple times he’ll show up and comment;-)

Dan


(Vince) #27

Imo the off the shelf compact routers are a wear item and easily replaced when worn. The Makita can be had for little over $100 shipped with 4 year warantee. A couple years of hard use is pretty dang good. I also run a sock (take it off for photos).

@RichCournoyer already expressed that the brushless looked gutless.

Digital VS Analog, pretty interesting


(Richard Cournoyer) #28

I did some rough math (in my head):

The brushless (Battery) Makita is rated at 1.25 hp = 930 watts.

FYI Ohms law…Watt = Volt X Amp.

That means this little tine armature needs over 45 Amps at 20 volts.

There is no way in HELL that this can take that much current for more than a few min (maybe 15 min).

So who thinks this is a good substitute for the TR0700?

Granted you don’t need to run it at full “balls to the wall” setting, but we’re talking “Vince the Man” here…Time is money…

I am curious to see Vince try it…and to see it go up in smoke…


(Vince) #29

Now I’m wondering if there is a way to trigger feedhold automatically if this thing dies quickly. If not I’ll test using heavy adaptive horizontal runs @28k and stand ready. I could see what kind of amps this thing pulls easily as well under load and no load conditions

Trial by fire as they say

I love the math, but I’m also optimistic. Time IS money, but everything has a scale. Ac/dc compatibility is a big benefit for my long term goals.


(Dan Nelson) #30

This forum is awesome! I think if it had existed in the far off past it may have been possible to bring Edison and Tesla(the man, not the car) here to discuss the merits of AC versus DC,…without the need to electrocute an elephant! Great discussion brings great ideas, and great ideas aren’t always followed by “Hold my beer and watch this!”. I’ve got my tinfoil hat on and I’m watching eagerly!

Dan


(Vince) #31

if I was a betting man I would probably put my money on Richard.

How does Makita rate the rt701c @ 1.25 hp and claim 6.5amp draw? ohms law doesnt apply cleanly to ac power right? Most charts i see claim 6.5 amps for a 120v ac motor to be anywhere from 0.5-1hp, and thats no load.

I have zero education on electrical and maybe im missing something but what if the RT701c isnt really 1.25 hp


(Tex Lawrence) #32

@Vince.Fab

How does Makita rate the rt701c @ 1.25 hp and claim 6.5amp draw?

HUGE SIMPLIFICATION

A BrushLess DC (BLDC) motor contains its own electronic switches instead of a commutator that is mechanically switching/reversing the polarity. These electronic switches are essentially ON or OFF with very little power consumed in the switch itself. In other words, at the moment one of these switches is ON, it has very little resistance to the current flow. (Note that brushes, which a BLDC does not have, are high resistance switches and are even momentarily power-consuming short circuits as the rotor rotates.)

So, during the momentary ON state you would calculate (via Ohm’s Law) very little power “wasted” by the switch itself. Conversely, there would be more power available to produce more torque for rotor movement.

As an aside, the momentary ON state is also duration tuned to only provide enough current to efficiently operate the motor, thus saving current there, too.


(Gary Mitchell) #33

That’'s probably “Peak HP” which is more a marketing term and factual from my experience.


(Tex Lawrence) #34

“… probably …” Is Makita normally overstating its ratings? It is really easy to write off everything to “marketing”, but BLDC motors will surprise you; just look at the tiny fans that are around. They didn’t show up until BLDC motors became abundant.


(Phil Thien) #35

Am I the only one surprised to see a certain someone hasn’t started milling an aluminum enclosure for his new brushless motor guts?

I know that is coming, he just hasn’t figured out how he is going to do it yet. Probably a stack of .5 or .75 pieces of aluminum.


(Vince) #36

15amp power supply came in, wired up, voltage adjusted until it had 30krpm max.

Ran 100% no load for 5 min, barely any heat buildup. Tone is very different. I’ll run cutting tests tonight and see if I can measure amp draw.

Check


(Griff Carpenter) #37

Cool, pun intended. Is that for router or ps or both?


(Stephen Gullage) #38

I did the math too, and I agree that some numbers are wonky. Based on the real world test of the 5Ah battery lasting 30 minutes, it would seem that the continuous power is roughly in the 1/4hp range instead of the claimed 1 1/4hp.


(Vince) #39

Handling adaptive great at 22krpm, 75ipm, 0.04 opt and 0.08 Doc. This is super conservative for me but I’m running on the stock s3.

@Griff Motor is 80 degrees after almost 100% continous load cutting. I’ll get some decibel ratings tonight, just cause I love you guys. Power supply not even warm.

That was one a 3 flute 250 TAS with one tip missing, switching to good 250 single flute.


(Phil Thien) #40

So you adjust the power supply to give you the 30k no-load, and then adjust the speed using the speed control on the router itself?


(Vince) #41

I turned the voltage trim down before I started testing. Full speed only went to 27.5, adjusted the voltage trim up until I hit 30krpm top speed. Then I adjust the router speed like normal with non contact tacho

0ver 30 min continous adaptive cutting, no issues, no heat soak at all. Ran the 250 single @ 3 thou chipload. That was a 2"x2"x2.25 block before milling.

Pretty impressive for under 360 watts :wink: