Brushless Makita mod


(mikep) #82

I’m sure you could, but it’s pretty expensive (SuperPID). It’s a lot cheaper to add gcode on/off (~$25).


(William Adams) #83

You an get a 3/8" collet for the Makita RT0700/0701 — it’s the same one here, or you can get one from Elaire Corp.


(Vince) #84

Had a chick come over to the shop last night to check something on her S2000… needless to say I didn’t get any real work done. Fun night though… hahaha

Data! Here’s no load numbers with voltage adjusted to max RPM. Its actually pretty interesting, amp draw peaks right around 25krpm.

Now to do some heavy adaptive. Also I am going to get help from a motorsport wiring buddy of mine to build a relay setup to trigger feed hold on sudden loss of router power.

I don’t think we’ll see 15 amps peak under load. Im guessing 10-12.

Still this option is looking good for a tinkerer. Lightweight power and good amount less vibration I feel than the corded rt701c.


(Vince) #85

0.250 HSS single, adaptive 40ipm, 0.100 doc , 24k, 0.00166 chipload, 0.040 opt. Chips look beautiful . 0.82 amp no load, Spikes to 1amp then settles at 0.88 loaded.

Same endmill, adaptive 40ipm, 0.200 doc, 22800rpm, 0.00175 chipload, 0.040 opt, chips are ridiculous. Spiked to 1.4amps initial load, settled to 1.22 constant load. That’s 27 watts folks

I’m ready to step up to 3/8s and see what happens. I think we’ve all grossly overestimated how much power it actually takes to cut metal :joy:

Alright things got interesting, I learned to see the actual peak amps on the meter and they spike a good amount. I actually blew the fuse in my power supply but the weird thing is that it’s a 6.3amp fuse. The power supply was rated at 15amps in the description. Time to return it and get the bigger one that griff is using.

Good news is the TAS is ok!! That was my main concern. I was cutting at 120ipm, 22krpm, 0.200 doc 0.045 opt, decently aggressive. Power supply couldn’t keep up, slowed down a bit then it died. Max amp pull was 13.25 but continuous load was not even 2.

Still no magic smoke but at least we got a “Pop”. Router showed no signs of stress, just needs more juice. 24volt 20amp 500watt power supply on its way!

Oh yeah. Only one Mitee Bite Hex holding the whole part in my custom fixture plate. Wanted to try some minimalist work holding like I saw Saunders do with Ed’s tombstone…but be successful.


(Griff Carpenter) #86

Really nice to see some real world numbers Vince.

I noticed the Brushless seems to have a smoother feel too.

Still fighting chatter in Y+ with just semi aggressive adaptive (only toolpaths I’ve run so far). I guess my XL is just too wide to be pushed too hard? But then again, no real need for me to push, I’m in no hurry. Just my nature to test limits.

If these cheap PS’s can’t cut it we can always try the Meanwell’s.


(Gerald Mackelburg) #87

Assuming you’re measuring the input to the router, you’re using a 600A AC current probe to measure pulse width modulated (PWM) DC currents that likely won’t exceed 10A RMS. It won’t work.


(Vince) #88

All I know is that I was told to put it on the Amp setting and clamp around the positive input. Is there another way I should be doing this? The manual doesn’t cover much

Also what wont work? Sure looked like it was. It is a true RMS meter.


(Gerald Mackelburg) #89

It’s a true RMS voltmeter, but AC ammeter.

You’re only measuring some of the AC content of the current. The duty cycle of the PWM waveform (whose switching frequency is likely above 20 kHz) increases with increasing router load. It should be pretty close to 100% (pure DC) at full load and your AC current probe would measure 0 A.

By the way,if you can measure the resistance of one or more of the router motor’s windings, that will tell you how much current can be drawn from whatever supply voltage you choose (I = V / A).


(Tex Lawrence) #90

@Vince.Fab , I’m in agreement with @gmack. Not to distract you from your main interest in cutting aluminum, you’re in over your head when posting current measurements from a BLDC motor. Meaningful values can get complicated. No offense meant.


(Vince) #91

Electricity isn’t my thing so just tell me what to do lol. I also have this meter available. I know I’m in over my head. I can take the router back apart if needed.

Also my main interest is trying new ideas, pushing percieved boudaries. I really wanted to give some type of data that would tell us how much power this thing is consuming. Not just make it work after everyone said it wouldn’t.


(Gerald Mackelburg) #92

If your meter wasn’t limited to 400 Hz for RMS voltage measurement, and it could accurately measure the RMS value of low duty cycle high frequency PWM waveforms, you could use a current probe to convert the current to voltage. But, most DMMs only measure voltages accurately to 400 - 500 Hz, so you’d need to use an oscilloscope with a current probe. If you’re willing to spend over $3000, you can get a really nice scope that make those types of measurements easy.

There are less expensive options that require considerably more effort.

IMO what you’re doing is really worthwhile, even without the power measurements. Cutting power is the product of material removal rate (cuin/min) and the unit power of the material being cut (HP/cuin/min). For 6061 T6 aluminum, that appears to be about 0.2 HP/cuin/min.

You can also get a measure of cutting power by using the battery with the router and measure how long it takes to discharge under various cutting conditions vs. when its not cutting.


(Griff Carpenter) #93

@gmack and @CrookedWoodTex, thanks for chiming in. So we need a friend with an O scope? Anything else?


(Gerald Mackelburg) #94

As I added to my previous post, it would be a lot easier to just see how long it takes to discharge the batteries under various conditions. If the battery specs are correct, discharging it over a 5 hours or longer could be quite accurate.


(Phil Thien) #95

You can measure the power supply’s consumption. Switching supplies are very efficient and what is being consumed should approximate what is being produced.


(Gerald Mackelburg) #96

Switching supplies also use high frequency PWM - so that won’t help.


(Griff Carpenter) #97

Seems simple enough. You have a Makita battery Vince?

I have a 6s, 5000 maH but no comparative baseline


(mikep) #98

Output is high frequency, input is still 50-60hz mains. Assuming is a cheap supply, something like 75% efficient, multiply by 1.25. If you have an efficiency rating for the supply, use that. Don’t worry about the output.


(Gerald Mackelburg) #99

Output voltage is DC (via output filter), input current is high frequency PWM to enable the use of smaller transformers.


(mikep) #100

No. Input to the power supply. It’s plugged into the wall. It’s 50-60hz 110-120v. Measure power into the power supply, not the output to the router.


(Gerald Mackelburg) #101

I stand corrected, “The current drawn from the mains supply by this rectifier circuit occurs in short pulses around the AC voltage peaks. These pulses have significant high frequency energy which reduces the power factor”. So, RMS current measurements likely aren’t much/any easier on the input than on the output.