As the topic states,
which one of these should I get? And why?
The former seems to be discontinued and the latter is cheaper.
I think we were over this:
I don’t see a disadvantage of the new one. It also has got more RPM as far as I know. But maybe we can find someone who has actually got a 702. I think I saw someone use it in another build.
Yes, I did ask a similar (maybe even the same) question there!
What I am asking is if the RT700 is preferred over the RT702? The RT702 is available here and it’s a lot cheaper but maybe not better. The CX5J seems to be a add-on kit with some mounts.
Yeah, the other letters/numbers beside 700/701 or 702 are all just mounts and grips and whatnot.
I just searched through the build threads but I can’t find the one with the 702. I am pretty sure I did see it here.
I am looking at milling MDF and plywood, do I need the extra RPM?
Can you control the RPM of RT700 with software? Or is it manual with the fingers only?
I don’t have an “extra” variable speed router to pull apart, but I’d be interested to know if the “power setting” provided by the onboard thumb wheel ended up sending a simple variable voltage to the onboard controller. If so, I’d think it would be easy to feed it a signal from the CNC control board.
Of course, I haven’t dug in to one to try and figure it out. So far my experience is limited to implementing the speed control that used to be available as a DIY solution through the V1 shop. Maybe it’s time to start shopping for a used variable speed router to experiment with.
If I had 500€ lying around I’d buy one of those: Fräsmotoren | Produkte | AMB-ELEKTRIK, maybe even with digital control.
am looking at milling MDF and plywood, do I need the extra RPM?
Unlikely. The “correct” RPM is calculated using the bit diameter, number of flutes, and the feedrate. I cannot think of one time since I purchased a variable speed router, I’ve run a CNC job at full RPM (30,000).
Can you control the RPM of RT700 with software? Or is it manual with the fingers only?
Fingers only. I think I read somewhere there is an add-on board to allow the RPM to be set via g-code, but my searching is not turning up the reference. Many people add a relay switched by the control board so they can use g-code to turn their router/spindle on and off.
I haven’t tried it yet, but I just found this on Tindie:
It looks promising…
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Looks very cool. Be aware this is an analog solution, and it expects 0V to 5V. It is unlikely to work well on 3.3V pins.
It does say, “Maintains the factory closed loop speed control.”
I think it will work fine with my 6-pack controller
I think that this is worth trying and that controlling the RPM with software is the way to go.
So perhaps someone could design a pcb that turns the router on and off and controls the rpm.
I just plugged it into an outlet I wired to one of those red/green on/off buttons.
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I ordered the PCB from Tindie that I linked to above. Hopefully it will be easy to connect it to my router and GRBL controller
Update as you proceed forward?
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Here are the instructions for the GRBL_SPD board. It does look neat:
It looks like they stuff a small relay inside the makit and replace the dial for speed control. I have some reservations about electrical tape as a long term solution, and this is AC wiring, so it is dangerous.
It definitely looks promising.
It has been a really long time since I did analog electronics. So consider this just a guess. I don’t think the chip is a microcontroller. It looks like it is maybe an op amp and analog circuits. The speed pulse increases the signal a little, it decays over time and it compares to the input signal. There is a little trim pot to adjust the setting.
So 1) A pwm probably won’t work. An LC circuit can smooth out a PWM to analog. Or you could use a true analog out. 2) I don’t have a reference circuit, but it may be possible to tune the system down to 3.3V. 3) Some kind of 5V analog out from 3.3V PWM premade solution would be nice. I bet they exist.
The fact that it doesn’t use a microcontroller is a blessing and a curse. No software engineer needed (plus) but no flexibility.
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