real world motor differences?
|Red Mallee||26/07/2021 01:56:11|
|2 forum posts|
In practice is the brushless on the SX2.7 noticeably better than the brushed X2.7? According to the local listings they are both 750W.
I know the theory says DC brushless is far superior.
I would have thought this well discussed, but after 2 days of looking I cannot get any real feel for the real differences in these 2 motors - unlike the X2 vs SX2 where it's chalk and cheese.
As an aside, ARC list the X2.7 as discontinued, but it's available here and a fair bit cheaper than the SX2.7 to the point that the SX2.7L is almost the same price as a SX3L!
|not done it yet||26/07/2021 09:10:02|
|6279 forum posts|
Have you asked the suppliers for a comparison? They should know.
I would expect one of two reasons for change to brushless - either better or cheaper.
|697 forum posts|
The main difference between brushless or brushed drill motors is that the brushed variants are made of carbon while the brushless units use magnets to generate power. For this reason, brushless motors are better adapted, generate no friction, produce less heating and provide better performance. In addition, brushless units significantly reduce maintenance, which comes down to dusting and there is no need to replace worn brushes.
4689 forum posts
With battery brushless their ability to produce torque is amazing
I believe that brushless is achieved with electronic switching of the current as opposed to manual carbon brushes
A bit like electronic ignition compared to points in a car distributor
21315 forum posts
A lot of other brushed motor mills of this type have some form of 2 stage Hi/Low speed ranges either by swapping belts or gears so that the motor can rev higher and be more within it's torque band at lower spindle revs. The X2.7 does not have this so you may find it lacks torque at the lower speed range particularly when using larger diameter cutters such as slitting saws, face mills and flycutters.
This is not such an issue on the brushless SX2.7 as the brushless motors produce a better torque curve starting lower down the rev range.
You also don't get the tapping function on the X2.7, but that's a minor issue unless you intend to do a lot of tapping.
As for the long table versions, get one if you intend to do a lot of long work, don't get it if you intend to just leave a vice at one end and say a rotary table at the other, better to swap tooling and avoid excess overhang as even the standard table is quite long for the size of mill.
I think the reason ARC stopped stocking the X2.7 was it sold far less than the SX2.7 so better to keep a good stock level of the ones that sell rather than have the others sitting in the warehouse unsold.
7482 forum posts
I suggest the difference between 750W brushed and 750W brushless isn't worth worrying about much. Both motors are adequate to that size of mill.
Brushless have more low-end torque and no brushes to wear out, but the electronics are more complex. Brushed are a tad or two less efficient than brushless, but they don't fail my 'so what?' test.
All things being equal, I'd buy brushless, but either will do. My mill has a brushed motor because that's what came with the biggest mill I can accommodate. To me the physical size of the machine was more important than the motor.
The single-phase motors used on Myford lathes are a glaring poor motor choice. Compared with other types their performance is bumpy, and noisy, and they have low starting torque. They're also unreliable due to capacitors and a centrifugal switch, and are unsuited to stop-start operation as required by a lathe. Yet this long list of disadvantages hasn't damaged the reputation of Myford lathes, on which huge amounts of good work have been done! The reason is single-phase motors are 'good enough' - they don't need to be wonderful. However, if I owned a Myford with a clapped out single-phase motor, I'd replace it with 3-phase / VFD, or brushless, or brushed DC. The improvement is worthwhile, but not essential.
Lesson learned from my beginner days was not to waste too much time dithering about details. If as a learner you don't know exactly what's needed, you might just as well buy the biggest you can afford and explore learn from it. Too much choice, many far eastern machines in various shapes and sizes, plus affordable ex-professional kit sold cheap and in good nick because they've been made redundant by CNC. Rather than spend months analysing the market, make a start, learn the ropes, and upgrade later if necessary. I suggest vertical milling machines are so similar, they will meet learner needs. Experts know different, but that comes with experience.
|Red Mallee||26/07/2021 12:49:55|
|2 forum posts|
Thanks. I guess my question really was "is anyone with a X2.7L sorry they didn't get a SX2.7L for torque reasons?"
I am very aware the brushless is superior but a 750W motor is not insignificant regardless, just ask any horse drawn carriage
Jason B, yes I could not see a gear switch so assumed low speed torque on the X2.7 must be usable at least.
Dave, you are right but I do not 'upgrade' easily and tend to end up putting up with what I've got, hence the need to choose more carefully in my case.
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