G540+Keling KL23H276-30-8A - wire 2.1amp series or 4.2amp parallel?

[wildwhl]

Hello -

I realize the Gecko is limited at 3.5 amps. I have 3.48K resistors in hand, as well as 2.2K.

I just took the plunge for a Gecko G540 and a 48V power supply. Currently, my x2 conversion uses a 4 axis TB6560 with 24V power supply, and while it works really quite well, I lose steps on occasion and am hoping this upgrade will resolve some of the issues, and get me better than 30ipm consistent rapids.

Anyway, my direct question is: Will I get more consistent performance wiring the motors bi-polar-parallel and limiting to the <3.5 amp current, or am I better off staying series as I am now at the 2.1ish amps current?

Small mill, so high rapids aren't necessary, but 60-80ipm would be nice.

Unfortunately, due to budget, new motors aren't a possibility (though they might be in the future - when I move these and the TB6560 to the lathe).

Thank you for the input.

WW

[wildwhl]

Anyone?

[ger21]

What's the pitch of your screws? Either way may give you the results your looking for, but parallel might have a little higher speeds.
The only way to know for sure is to probably just try both ways.

[wildwhl]

Thanks Gary - 10 TPI on the x and y, 5 on the z

I guess, even though I've read a bunch, I'm still confused about how to maintain the best torque. My head is wrapped up in the fact that they'll be undercurrent in parallel, and possibly underpowered in series?

They are running series now and seem to work well, other than the anomalies from time to time with lost steps. It is possible these are related to torque/leverage issues and that is why the mill is apart with new gibs being cut, lapped, etc.

WW

[ger21]

Even if you keep them in series, the fact that you're doubling the voltage, should double your speed.

By wiring them parallel, you'll sacrifice 15-20% of your low speed torque, but may gain a lot at the top end.

[wildwhl]

Alright - so - are you saying that series will actually give me better low-speed torque (say below 20ipm, or 200rpm - correct - with 10tpi screws?) than parallel would due to the fact that I can't push them with 4.2 amps (still try to get my noodle around it - but I think I get it).

Bill

[rowbare]

I would recommend going bipolar parallel.

Those motors have a fairly high inductance 6.8 mH parallel and 27.2 mH series.Using Gecko's rule of thumb equation 32*sqrt(inductance), this means the motor would work best at 83 volts parallel or 166 volts in series. Given that you have only 48V available, I would expect that you would get better performance overall running bipolar parallel.

This post should help explain things: http://www.cnczone.com/forums/showpo...0&postcount=11

bob

[wildwhl]

Whoops, I totally blew the initial post. Happens when you work too much I suppose. The motors I have are:

http://www.kelinginc.net/KL23H276-30-8A.pdf

not the ones listed in first post (I will edit that). Inductance is 2.2mh parallel, 8.8 series...so using Gecko's equation parallel+48V would be just about perfect, yes?

My apologies.

Bill

[rowbare]

Those are nice motors and work well with the G540. I have them on my Taig mill. I run them Bipolar Parallel with the 3.48k resistors. They derate to about 233 oz/in at the lower current.

bob

[wildwhl]

Excellent Bob - Thanks!

Bill

[Crevice Reamer]

Definitely go with parallel wiring.

I do not recommend those motors for G540. They are a little underpowered for the X2 and may still lose steps.

For best results use the 381s:
http://kelinginc.net/KL23H2100-35-4B.pdf

CR.

[wildwhl]

Thanks CR. When the budget allows, I'll look for those and swap these onto the lathe...

Bill