Also a small pulley and twine using a simple spring scale is another way which has worked,
The motor would be energized at the plate rated voltage/current.

 

Also a small pulley and twine using a simple spring scale is another way which has worked,
The motor would be energized at the plate rated voltage/current.

That method will give the stall torque, it is not able to display running torque delivered to the load, like on a dynamometer..The TS asked for a method of reading the torque required to turn the load, the engine being broken in. The scheme I described is a smaller version of the classic engine dynamometers used for automotive research. AND I am guessing that the TS is quite competent mechanically, able to visualize and assemble such a setup.

 

That method will give the stall torque, it is not able to display running torque delivered to the load,

In a stepper, as the stepping rate increases, so does the BEMF, causing the current to decrease and hence, torque.
In order to overcome this, a modern drive uses a much higher voltage in order to maintain the Motor Rated current and therefore the torque curve can be kept fairly flat up to a certain point.
Much higher than without this drive feature.

 

A friend of mine suggested a AC servo drive instead of a stepper motor. I have 0% experience with AC servo motors so I don't even know if that is a reasonable suggestion or not. He explained that I would be able to measure all the parameters I mentioned but I question if a servo motor will be able to spin fast enough and have enough duty cycle so it doesn't eat it self. But like I said I have no experience with these except for RC servos which I different. Thoughts? By the way you guys are great. Thanks for your help! You guys have made this a fun and exciting project.

 

So do you require precise RPM's?
If not, a simple DC motor, open loop may suffice , the very precise RPM would not be exactly critical would it?

 

If the performance of a stepper motor has been adequate why change??? And since the present arrangement seems to produce good results, and since it is also clear that we do not understand everything about breaking in small engines, or the current process, it seems like not changing everything at once is a better choice. Understand that at best, only half of all changes result in improvements.
Reading RPM is just a matter of scaling the measured pulse rate to display revs per minute from measuring pulses per second. That can easily be made accurate within 0.1%.
reading torque can be done in a manner similar to the older engine dynamometers , or it can be done with an in-line torque transducer, but if the speed is fast and the times are long then replacing those in-line torque sensors will get expensive as they wear and need replacing. A simple torque measurement scheme reading the motor reaction torque is a much more durable way, easier to calibrate and less expensive as well.
Of course, here I am guessing that to spin the engine being broken in, the setup is vertical above the oil bath. That may, or not, be the case. It is probably a secret process that I really do not need to know about.

So I suggest that the TS investigate engine dynamometers to understand what I am suggesting about reading driver reaction torque to know the engine torque. The concept is not new at all, except for using a load cell instead of an actual force scale.
It might be that utilizing something like a torque wrench dial indicator could be adequate. That might be a simple option if the range and accuracy were withing the requirements.

 

So I suggest that the TS investigate engine dynamometers to understand what I am suggesting about reading driver reaction torque to know the engine torque. The concept is not new at all, except for using a load cell instead of an actual force scale.

From what I read so far he's not interested in the torque. he's just using the stepper to turn the ICM for break in. And for the price of a simple DC gear motor and a speed controller we can eliminate his problems.

A DC gear motor with the targeted RPM and the speed control to slow it down if needed.

 

From what I read so far he's not interested in the torque. he's just using the stepper to turn the ICM for break in. And for the price of a simple DC gear motor and a speed controller we can eliminate his problems.

A DC gear motor with the targeted RPM and the speed control to slow it down if needed.

In post #4 the TS mentions "being able to know the load", which the load on a motor is the delivered torque. Thus my description of dynamometer schemes.
In addition, the TS already has been using a stepper system for a while, so why abandon what has produced the desired results.

 

" the TS already has been using a stepper system for a while, so why abandon what has produced the desired results "

The OP stated off the bat, the present set up is not that perfect. If they produced the required results, presumably there would be no need for the thread?
For me, I would not really consider it all that necessary to break in a RC motor?
Also are these being turned-over/spun under compression or not?
This would influence the nature of the mechanism, i.e., requirement for a flywheel etc.

 

Of course the engines are being spun with compression, without compression loading there is not much effect on the connection rod nor any bearings. And after mentioning that the system was not perfect, the shortages were described and lack of RPM and torque measurements and also incorrect operation in the reversed mode. None of those would tend to indicate a desire to replace the entire system.

 

Sorry for not being able to respond for a few days. Easter, my fathers birthday, and my kid being off of school for a week. I haven't had much time to test the new power supply. So last night I had a bit of time. I installed the new 30 Volt 15 amp adjustable power supply. I set all the adjustments. I turned it on it much excitement............. and the stepper motor still has the problem. It still will function in one direction and when I try to use it in the other direction the motor stops during part of the revolution. Well on to replacing more parts so I'm going to start by replacing the device that adjusts the speed and direction of the motor.

To answer some of the questions above:

The OP stated off the bat, the present set up is not that perfect. If they produced the required results, presumably there would be no need for the thread?
I'm open to replacing the entire system if I'm able to get the results that I'm hoping for. Those are knowing the RPM, load, duration, and oil bath temp. the last two items I have figured out.
For me, I would not really consider it all that necessary to break in a RC motor?
I explained this in a earlier post. High end RC stuff. One engine alone is around $1000.00 and that is before modification is done. That is just the engine not the whole plane.
Also are these being turned-over/spun under compression or not?
No not under compression. With engine head, carburetor, and back plate removed for as much oil flow as possible.

 

No not under compression. With engine head, carburetor, and back plate removed for as much oil flow as possible.

I couldn't quite see a 2 cycle internal compression engine immersed in oil and under external rotation.
Hydraulic lock!?

 

It still will function in one direction and when I try to use it in the other direction the motor stops during part of the revolution

Why would you need or want to run your break in motor in reverse?

I'm open to replacing the entire system if I'm able to get the results that I'm hoping for. Those are knowing the RPM, load,

Like I said earlier a DC gear motor rated at the highest RPM you need( you haven't said what that is but if using a stepper motor it can't be too high of RPM) then a DC speed controller to vary it to a lower RPM if needed. A pretty good source for motors - https://www.surpluscenter.com/Electric-Motors/DC-Gearmotors/DC-Gearmotors/

 

Why would you need or want to run your break in motor in reverse?

I don't want to break in the engine in reverse. That is one of the major problems I'm having with the current system. I cant break any engines in currently due to this problem.



Like I said earlier a DC gear motor rated at the highest RPM you need( you haven't said what that is but if using a stepper motor it can't be too high of RPM) then a DC speed controller to vary it to a lower RPM if needed. A pretty good source for motors - https://www.surpluscenter.com/Electric-Motors/DC-Gearmotors/DC-Gearmotors/

In regards to DC gear motors you are speaking of what kind of RPM can these geared motors spin. Looking on the website you sent really quick it doesn't look like it would be fast enough. I'm looking at somewhere between 0 - 1500 rpms. When you first start the process you start it slow and increase the rpms as the engine breaks in. Depending on the engine the break in process can take between 6-12 hours of running. Also why I want to see the load the stepper has on it. The load would also indicate how far into the break in process a certain engine is compared to another one.

 

I am tending to agree with @shortbus, the better option maybe a open loop DC motor, a stepper motor is going to run at a constant speed when unattended.
A DC motor ran with a precise PWM signal could be used and at first the data could be extracted by running a already broken in motor and record RPM and current at the required RPM point.
When breaking in a new motor, first the initial RPM and current could be recorded, as the system runs, the RPM's will rise and the current will drop.
Once the same RPM and current is reached as recorded by the initial test the motor under power should match the run in state indicated by the now broken in motor ,
With a stepper motor, it is customarily ran at a constant rated Current, i.e. speed will not vary, if unattended .

 

In regards to DC gear motors you are speaking of what kind of RPM can these geared motors spin. Looking on the website you sent really quick it doesn't look like it would be fast enough

I only sent you there because you never gave an RPM and 1500 is really really fast for steppers. When you kept saying steppers I thought you were talking slow RPM's. That said, I can't see where 1500 RPM would break an engine in any better than say 500 RPM, it would just be faster with 1500RPM.

And like Max said you would read how the break in is coming along just like you would with a stepper, by the amp draw on the motor.

 

I am tending to agree with @shortbus, the better option maybe a open loop DC motor, a stepper motor is going to run at a constant speed when unattended.
A DC motor ran with a precise PWM signal could be used and at first the data could be extracted by running a already broken in motor and record RPM and current at the required RPM point.
When breaking in a new motor, first the initial RPM and current could be recorded, as the system runs, the RPM's will rise and the current will drop.
Once the same RPM and current is reached as recorded by the initial test the motor under power should match the run in state indicated by the now broken in motor ,
With a stepper motor, it is customarily ran at a constant rated Current, i.e. speed will not vary, if unattended .

Interesting........
Send me a link with a suggestion to a dc open loop motor and driver and Ill take a look. I understand that my current system isn't perfect but it is pretty close. I want to get to a point where I can write a program for this system to work in a automated way. I know enough about programming to do this(Not a Expert). I don't believe that can be done with a open loop dc system.

 

I only sent you there because you never gave an RPM and 1500 is really really fast for steppers. When you kept saying steppers I thought you were talking slow RPM's. That said, I can't see where 1500 RPM would break an engine in any better than say 500 RPM, it would just be faster with 1500RPM.

And like Max said you would read how the break in is coming along just like you would with a stepper, by the amp draw on the motor.

These engines are very unique. 500 rpm and 1500 rpm make a very big difference. If you start off the break in process at 1500 RPM there is a very good chance you will damage the connecting rod. The break in process has to go in steps. If you try to go too quickly the engine quickly ends up broken. LOL. Pistons will break, connecting rods will split, the cylinder bore will oval. The break in time takes between 6-12 depending on the fit of the piston and the bore. Every engine, even from the same manufacturer is slightly different and will break in slightly different. I'm fully open to suggestions on any type of system. I don't have much experience with other types of systems so when I built this first one I stayed within my knowledge base. If you guys want to send me a few links I will build another machine with a different system just for testing purposes. Heck I would be willing to build 5 more systems to get it perfect. Depending on how crazy the cost of the other systems are of course. I'm not afraid to throw some money at this. When your trying for the 1% of anything it is going to cost you some money.

 

Using a DC motor of suitable torque rating,
One method is to manually set the voltage that results in a suitable starting RPM, the rpm should increase proportionately to the load (wear).
Monitor the RPM in order for a switch off when the desired maximum RPM is reached.
If the RPM does not increase over a given set time, increase motor voltage in small steps.
Could be done manually or automatically using RPM monitoring and motor voltage control..
With a stepper motor, the current is the plate rated value throughout the RPM range. (0 to Max).

 

If high speed can cause problems but low speeds work, and depending on the complaints about the stepper system. I already described the arrangement for measuring torque, and selecting a slow speed is simple. A DC motor can easily achieve 5000 RPM in about 2 seconds, too fast to switch off, while a stepper is more likely to stall. And if a low-speed limited torque is the best way to break in an engine, then a stepper is far more able to do the task well.
What is not clear to me is if the higher voltage supply solved the rough reverse rotation issue or not.