I felt that I said more than $.02... no inflation, just additional opinion ;)
I don't want to argue more but will answer some of your questions. I posted the motor specs, other than the dimensions. I can measure one for you next time I am in the garage if you like. Brushes are a common size and about $10 a set IIRC. I got lucky and the brushes are like new in the 6 I got. I wrote that the encoders are either 500ppr or 1000ppr. That itself indicates that they are absolute encoders. They are not differential, but you don't need that anyway with the mesa interfaces. I mentioned that I didn't pay the buy it now price but made them an offer. If you would like to pay the asking price, that is your choice. I understand about the feedback rating and you have to do your own investigating and make up your own mind about taking that chance. It is definitely worth paying more from a better rated seller sometimes. My first purchase was from another 'seller' from the same company that had a high feedback score but I bought the last ones that seller had listed. The next ones were from the link I gave. Electrocraft still makes essentially the same motor under a different model number (they changed all of their model numbers) if you want to spend for new price. Yes, a 7i33 quad analog servo interface would communicate with any of the +-10v input servo amps. The 7i33 also has four encoder input connections. Since you only need X and Z you can use one of the other outputs and encoder counters for your spindle if you so choose. A 7i42TA, or many other options, will get you home, limit, and estop switches and any needed outputs. On 02/06/2017 12:28 PM, Gene Heskett wrote: > On Monday 06 February 2017 08:27:11 dragon wrote: > >> Tormach has a pretty good white paper on why they chose to use 3 phase >> steppers on their machines. I found it a great read for future >> reference even though I was going to use servos anyway. >> >> On another note... you can get E661 servos with encoders off of ebay >> for $40 to your door and they are a great match for your Sheldon. Grab >> some used servo drives for about $50 each depending on your power >> supply situation. That is certainly cheaper than the 3 phase steppers >> that you are looking at. Personally if I was to do 3 phase steppers, I >> would go with the Leadshine stuff. >> >> Just my $.10 > > I see inflation has hit the 2 cents define. :) > > With shipping added to the $52 they are asking today, about $75 on my > front deck. And this guys feedback rating is crap at 85%. The next guy > has a 100% rating and wants $65 for it, then $72 something from the last > peddler. > > But zero data, and that model is so old Electrocraft's web search can't > find it. So how much twist, what voltage & amps to get that twist, and > how long is it behind the mounting face? I don't really have a length > limit for Z, but X is not more than 115mm's. > > IOW, where can I find the info to use it? > > I am seeing mentions of up to 300 volts and 12 amps, but not in the same > advert links. These are brushed motors, can I get brushes? Its also a > change to a card to drive servo's, more bucks. As in $80 for a card that > slaves 4 servo's to the pwm signals from my 7i90. I assume those +-10 > volt signals can drive the amplifiers, but are the encoders position or > velocity tachs? > > Lots of questions I'm afraid, and a bigger bottom line at the end of the > probably 3 months it would take to get it all working. > > Thank you. >> >> On 02/06/2017 03:09 AM, Gene Heskett wrote: >>> Greetings everybody; >>> >>> I just spent an hour on wikipedia, and another hour reading >>> everything that google spits out on 3 phase stepper motors, and have >>> not found a convincing argument in favor of 2 phase, other than >>> their ready availability. >>> >>> I can get off fleabay, 3 phase, 230 volt ac powered drivers in size >>> & voltages suitable to move this lathe with, for a big buck + an if >>> it fits box from the USPO. Those are here, on the left coast. >>> >>> But no one on this side of either pond is stocking the 3 phase >>> version of the motors, and due to their weight, its 2 to 4 weeks, >>> and another 56 bucks or so to get any of them because they are all >>> in China, so an $80 nema 34 is about $140 on my front deck. Close to >>> $250 an axis IOW. >>> >>> So I need to see a decent discussion on the subject before I cut >>> that big a hole in the card. >>> >>> Many thanks for any educational url's on the 3 phase motors you >>> folks can supply. >>> >>> Cheers, Gene Heskett > > > Cheers, Gene Heskett >
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