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I've seen some comments mentioning that the R-Pi is missing a real time clock, and comments mentioning clock add-on boards in this thread.

Just to make it clear: a Real Time Clock (RTC) keeps...

*LOL* :D



Glad you like it! :) You got the interval wrong, however... I guess you meant '1>x>0' - i.e. x is between 0 and 1? Your x is negative (less than one and less than zero :))

Arvid

Yeah, division by zero is a no-no. The result of dividing zero by zero is quite interesting:

x/x = 1
x^2/x = x
x/x^2 = 1/x

and

lim x->0 k/x -> infinity (k > 0)

"ie the oz. would go up and the distance down"

Yes, correct, for equal torque you would need to increase the force if the distance is reduced. But try it:

2 "force" * 5 "distance" = 10...

I'm not very comfortable working with pounds and ounces, but think about it this way:
You get more torque by either increasing the force or increasing the distance from the fulcrum. If you divide...

Ok, you guys can tell me to shut up if you're tired of hearing this... :D

Torque is the product of force and distance, so writing oz/in or N/m is wrong. (It would imply you could open a door...

A DIN type connector, perhaps? These have up to 8 pins.

Arvid

Hi studysession - cool project!

I've thought some about what would be necessary to convert a 1/8 scale gas truck to electric. It would be a very fun project, but I don't have neither the money nor...

You don't. You measure force. A linear motor doesn't develope any torque.

Mechanical power of a linear motor [W] = force [N] * speed [m/s].
Mechanical power of a rotary motor [W] = torque [Nm] *...

Ten micro steps count as one full step. So you get the 125 oz-in at 4000 full steps/s or at 40000 microsteps/s.

"4000 steps per sec/2000=2 revs per sec"
The error here is you divide full steps by...

ViperTX, he gets 1" of travel for every 1/pi revs of the motor.

dowling, your calculations looks correct to me. Kevin's suggestion of 9:1 ratio is probably due to the fact that it can be achieved...

Is it possible to have several input cells in an Excel spreadsheet, where the other ones are updated depending on what is entered in any of them? I.e., to be able to enter mass either as kilograms or...

The 200 Hz means you have to run them at 200 Hz to get 3000 RPM. 3000 RPM = 50 revs/s so I guess that means they are four pole motors?

Also since they've got encoder mounts I guess they don't...

Jay C, thanks for the correction! A new version has been posted (I had to start a new thread since I couldn't edit my old post anymore - perhaps it's too old?)

Arvid

The short answer:

For a smaller wood and plastic cutting machine (and maybe – maybe! – some light aluminum), several people on CNCzone seems to have had success with 100-200 oz-in (0.7-1.4 Nm)...

(chair)
Torque is force times distance, not force per distance.

Think about opening a door: if you pushed directly on the hinges instead of the handles, and if torque were force per distance,...

Servos keep their rated torque up to nominal speed, while steppers drop off in torque with increased speed.

Arvid

That would be carrots. (Sorry just couldn't resist it :D.)

:cheers: Arvid

But I can! (Help on the aluminium, that is :))

I just built this. (It's meant to be the start of a drill jig that hopefully will allow me to drill straight and parallel rows of holes for my CNC...

Encoder resolution is something I have really come to appreciate while building my controller card. If the max tolerable following error corresponds to 1000 encoder counts, then the error has ~10...

The holding torque will be the same as the motor's maximum torque. Turn the shaft harder and the controller will trip an excessive following or overcurrent error.



This is called control theory...

Einar, the VFD has got an output current readout. I simply used that.

It ran for maybe three seconds before I could turn it off. Afterwards I could feel the motor getting hot even after I had...

Ok, I just couldn't contain my curiosity anymore, so I tried it:

I connected a 3 ph PM servo motor to a V/Hz VFD. I set max frequency (= maximum motor frequency), max voltage frequency (= rated...

Mike,

Do not use the T style belts/pullies. These are made to have some backlash built in. I believe the same is true for HTD. Use the AT or GT2 instead.

(I am having the same...

The Yaskawa servos, at least, have the commutation information in the third (index) encoder track. The advantages/reasons for this are no hall sensors needed and less conductors needed back to the...

I like the table! Did you mill those pieces or are they some kind of standard part that can be bought?

Arvid

Your workmanship is just incredible! Nice work & hat off to you! It'll be a real treat to follow your new more detailed thread.

Arvid

They call them AC servos in the manual, and write "Control Method: PWM (sine wave driven)".

How do you define cogging? I thought this was some kind of magnetic effect in the motor. When turning...

I think you have been looking at the SGDAH drives (Sigma II series). The ones I've got are the older Sigma I, which can only do analogue speed or torque control.

I am just using an adjustable...

The motor is a Yaskawa SGM-02A3. They use encoder feedback only, with the third (index) track having some smart design enabling the driver to find exact rotor position in just a fraction of a turn....