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01-09-2014 #19
Ok first let me say NO where did I rubbish based on cost.!! . . . I rubbished based on fact and experience that these TB based drives are RUBBISH and Hi inductance motors give poor performance.! . . . If that's not what you want to hear then that's your problem it's still a fact.!
Also they are not value for money when the don't perform as desired or has often the case they let the magic smoke out.!
The fact no one is telling you what to buy is mostly because they can't accurately recommend anything without knowing more about the build.! . . . It would be wrong to give explicit recommendations without knowing more details.
What can be given is ball park setup that is generic to most machines of the size your suggesting. For some it will be OTT for others spot on but in all cases it will give great performance and reliabilty. . . This will be value for money.!!
What it won't be is very cheap as the simple fact of matter is to do this correctly so you get correct level of performance along with reliabilty requires a certain amount of investment.
This is what I've been saying regards you wasting money because what you have bought will be woe fully slow and under powered due to components being completely unsuited to each other and also configured in the worst way.
Hi inductance motors require higher volts compared to low inductance motors to push the current thru there windings and when wired in series like you have they require much more than 24v to get anything like decent performance. The drives won't allow more volts other wise magic smoke appears so your stuffed with this setup.! . . . . . Completely NOT value for money.!
Now your comment about "tendency to go "bigger" " is correct but also wrong at same time. This common tendency to go bigger is often done with nema 34 motors and fatal to performance for similair reason's. Mostly lack of voltage/cuurent and therefore speed/torque.
You only have to look around the forum to see the COMMON setup that works. This is not "Drive" or "Motor" snobbery or sheep following sheep it's simple fact that it this setup works for a wide variety of machine setups.
The setup is as follows. Now whether you pay the little extra and get the digital drives is a choice you may decide based on your wallet. Personally I will only use digital drives because of the advantages they give over analog drives. They are smoother, run motors cooler and in some cases give more setup options which can be life savers if resonance plagues you.!
One other thing is that often digital drives are better protected against wiring wrong or loose connections falling out which would other wise kill lesser drives (I know of several on this forum who have had there arse's and wallets saved by these features.!!) . . . . But analog drives still work good if correctly matched so it is choice based on cost that doens't have a massive affect on performance.
8 wire 3Nm 4.2A nema 23 motors wired in parallel. (inductance around 3mH when wired parallel)
2 common setups for drives upto 50Vdc or upto 80Vdc (80Vdc prefered for safety margins)
PSU 44Vdc upto 50Vdc drives: 68Vdc for 80Vdc drives.
The higher voltage setup is better not just for performance but also there's a larger safety margin drives and back EMF while still getting great performance.
One last thing regards belt drive. It often ends up costing the same or not much less has buying ballscrews from china by the time you have bought pulleys etc so check it out.
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