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Discussion in 'Sim Racing Hardware' started by eKretz, Feb 21, 2013.
I kind of wondered if notching the belt would help. What method are you hinting at? You coy racer, you.
RacerXX has his cooling already functional Cote, I just have to finalize my setup and then I'll share photos. RacerXX is more in the "show me yours and I'll show you mine" camp with the water cooling setup it seems, lol. Next he'll want to play doctor!!
I was hoping for pictures, Fbb fading test, while having mok applied to the motors, just curious.
Heh, not far off of old Colin Chapman's mantra.
Hmm, I just did a few little tests after setting up my new power supply, stall tested the Bühlers in parallel and singularly and then the Fana-Buchis. Interestingly, when holding the Fanas at stall @24VDC but slowly rotating the motor's shaft, they felt very jumpy/notchy, while the Bühlers felt like a perfectly constant smooth force. I also brought the motors up slowly from 0-30VDC under no load, just to listen. The Bühlers were smooth and quiet, but the Fanas were really acting odd. They were quiet for a certain amount of voltage change, then there would be a big jump in volume level for a certain range of voltage, then quiet for awhile, then a big jump, then quiet, etc. Sort of like it was fighting to build RPM, then jumping with a big increase, then fighting, then jumping, etc. These are brand new Fana motors too, never been in a wheel at all.
P.S. please disregard the copper coils on the motor here, this was just a scrap piece to see if the tubing would kink while wrapping and for a few preliminary tests. I'm making a jig for the final coils.
Both of these phenomenon are likely related to the armature design differences. The Bühler motors having the "spiral" armature and what looks to be more poles.
You think so? I'm not sure, I have a couple smaller straight armature 5 poles that are very smooth also. (The Fana-Buchis are 5 pole, the Bühlers 7 pole). It seems more like a cheap motor problem. Possibly brush contact related maybe? I really do not like the looks of the Buchi brush/comm interface. It's not so much a regular notchiness (or cogging effect, like I would expect the pole variation to feel) as a very weird irregular jumpiness. But then again, I'm no motor expert.
Cogging occurs when the armature poles align magnetically with the magnet poles in the motor. In a motor with a straight slotted armature, the poles will align in definitive location with relation to the magnets. In a motor with a skewed armature, these poles will be spread across the magnets causing the torque maximum to be "smoothed" All else the being the same, it is likely this has the side effect of decreasing the overall maximum torque output of the motor when compared to a similar straight slotted counterpart.
If you want to look more into the concept of skewed armatures you can just google that, there is a lot of information on it's use in overcoming reluctance torque (cogging).
That is good info, but how sure are you that's what it was? It didn't feel at all like the other 5 pole straight armature motor I tested (although as I said, it's a bit smaller).
Heh, or trying to intimidate the Killer Bees. Too bad they're all bark and no bite.
Ha ha, you sound like my ex. I will then ask you, how sure are you that is not the cause?
They are your motors to test. Your pictures of the armatures on your motors show they are skewed. So I hinted at this likely being the case for smoother operation. I have seen many of these motors used in low speed applications, often coupled with an optical encoder. Did your motors have one of these attached?
There are also harmonics involved as the motor changes speed which are in part caused by the reluctance torque as the motor moves away from the poles. This is also reduced/smoothed on the skewed armature design.
If I could recommend a process to you, it would be to clean your Mabuchi motors well and break them in. Then test again. You may be having some issues with the brushes. This will all be subjective.
The skewed armature design will reduce cogging force no matter as this is a proven design methodology. Maybe you can devise a method to measure cogging force. I can think of a few that would be suitable for use in comparative testing only. Only then will you have some objective data.
While the motors are free to move about, you should consider establishing baseline measurements of their efficiencies at different heat levels. I am somewhat surprised that this has not been done yet and/or posted.
It would be a good idea to establish what impact heat has on the motor itself and not only the circuitry through which it is being driven. Motors that are inefficient can experience significant decreases due to heat, especially in areas of the motor which cannot be directly cooled such as the armature.
I hope you do not mind my insight into these processes. Experiments by laypersons in such fields are quite interesting as the processes used often vary greatly.
Do any of you experts want to do some contract work? I'd like to move my CSR elite buttons either to an external box or to the space left by the removal of the airbag from my Porsche GT2 wheel. It's a custom project for my GT2 cockpit. Thanks
OK. Joan, it sems like maybe you are misunderstanding my last post. I wasn't comparing the Fana-Buchi motor to the Buhler, which is a skewed armature. I was comparing it to another 5 pole motor with a straight armature from my motor pile. The irregular notchy feeling at stall with the Fana-Buchi wasn't there in the other 5 pole straight armature motor. That motor also gained RPM smoothly while the Fana-Buchi had sort of fits and starts.
So anyways, since I felt pretty sure it had to be brush/comm related, I went ahead and did a water break-in on the Fana-Buchi. (As I said, this was a brand new motor fresh from Fanatec, so I hadn't broken it in yet). I ran it in both directions for a couple minutes up to 30VDC in reverse osmosis filtered water, then allowed it to dry out (helped it with a heat gun) and re-oiled the motor shaft at the bushings. After break-in it's running up the RPM under no load smooth as silk. At stall it is MUCH smoother, with only the slight regular cogging that I expected to feel the first time. So it looks like it was a brush issue after all.
Good call, I did have a feeling it was something to do with the brush contact.
I would be happy to do so, if you'd like to outline a good objective way to test this. I am happy to have another contributor, feel free to add your insight wherever you'd like. I am more experienced with the mechanical processes in modding, I am just getting more into the electrical side. I have plenty of experience with electrical mods, but only following a guide with modifications to circuits, etc. so I am happy to have you and RacerXX here to give some more insight into the electrical/circuits side of things.
Yeah I already saw most of that, the first time I ever pulled my motors I noticed how out of square it was. I'm thinking of making an aluminum heatsink/motor mount actually, have a few sketches made.
Ahh, just got done wringing this car out for a bit on GT5 at FFB 5 checking for wheel fade in a few different cars, reminds me of when I drove this one:
It seems like I get the most fade in GT5 with F1, FGT, and X2010.
I have a little helper who likes to climb up into my lap and interrupt me so my wheel gets a chance to cool down between tests:
He has made a mod suggestion here and there. Mainly he would like a sippy cup holder and snacks dispenser on the wheelrim, heh.
Cant wait to see if someone will try brushless motors someday.
Somebody could try that someday. I saw a guy in one of the forums, ISI maybe? who is making his own FFB controller, I think he said it was capable of running a brushless, and it's going to be free/shareware. He is going to make pcb's and offer them for sale too I think. Last I saw he was running a Bodnar wheel (motor) with his prototype.
On another note, mrbasher has had a discussion with me over PM and sorted out a few issues and explained a few things and I have told him he is welcome to contribute in this thread and any contributions would be valued. So hopefully we'll get some T500 comparisons and notes as well.
Well said. My understanding of small electric motors does indeed come primarily from the rc world so your statement made a lot of sense.
Getting ready to try out the new motors:
I'll let you guys know how it feels after I try it out. I'll probably do a cold wheelcheck graph for comparison just to check it out but I don't have my water cooling setup finished yet.
OK, here's a refresher view of the stock wheel's graph:
Here's the Buhlers @24VDC:
I haven't done a scale test yet, will get to that later today. Got the rugrat to supervise/feed/play with/teach. I haven't driven it yet either, should also be later today.
P.S. These Buhlers accelerate like a BOSS. Look at the graph how they're almost full speed immediately, and the reversal curve is MUCH sharper/quicker.
P.P.S. The graph legends are the same, primary y-axis is degrees rotation, secondary y-axis is force command and reported position. I was tired when I finished, so I forgot to title the graphs and label the axes, sorry!
Is VDC volts of direct current? If so what does the stock run at and why are you able to run the Buhlers at different Volt levels than stock?