Cannot go past 50 ipm!

[greenene]

Machine: K2cnc 2514 with .1 lead screw
Motors: Keling steppers 425 ozin 4.17 V 2.8A
Controllers: Keling 4030 max input voltage 40V max current output 3A
Mach 3 software
Power supplies: 36V 8 A for X and Y axis
36V 8A for Z axis

All axis in Mach 3 are set up for velocity of 60ipm, accel 3.5.
Resolution currently set at 4000.

No matter what microstep I use, these appear to be the maximum parameters before the motors start slipping.

Keling has suggested that I use 1/8 microstep, but it does not improve it.
Mechanicals appear to be fine: no binding, etc.

I am down to the following options:

A. 48 V power supply and larger controller
B. .2 lead screw
C. more powerful computer ( can it be that I need a higher frequency pulsing?)
C. give up

I am cutting mostly balsa, so I need more speed.
thanks in advance.

[TOTALLYRC]

Machine: K2cnc 2514 with .1 lead screw
Motors: Keling steppers 425 ozin 4.17 V 2.8A
Controllers: Keling 4030 max input voltage 40V max current output 3A
Mach 3 software
Power supplies: 36V 8 A for X and Y axis
36V 8A for Z axis

All axis in Mach 3 are set up for velocity of 60ipm, accel 3.5.
Resolution currently set at 4000.

No matter what microstep I use, these appear to be the maximum parameters before the motors start slipping.

Keling has suggested that I use 1/8 microstep, but it does not improve it.
Mechanicals appear to be fine: no binding, etc.

I am down to the following options:

A. 48 V power supply and larger controller
B. .2 lead screw
C. more powerful computer ( can it be that I need a higher frequency pulsing?)
C. give up

I am cutting mostly balsa, so I need more speed.
thanks in advance.

50 ipm = .83 in/sec * 4000steps/in = 3320 steps per second. even the lowest setting of mach3 will generate 25,000 steps/sec/axis

If you go to 1/8 mico step the numbers are not much worse, 13280/sec
You are still well within Mach3's capabilities at its lowest settings.

I am assuming that your .1 screw is 10tpi.

4000 steps/inch would indicate that you are running in 1/2 step mode.

One of the underlying factors is that those motors are rated for a max voltage of around 80v if memory serves.
Running them near half of max makes for slow going.


going to a .2 pitch screw means that you will be able to go almost twice as fast but not quite due to the increased power demands of going faster.

Mike

[greenene]

thanks for the quick reply. Your analysis appears correct. I am just wondering if the .2 lead screw tackles the higher torque/ poor high speed better, thus it might be a cheaper solution than a power suppy-controller combo. My working travel is relatively short.

thanks again.
tc

[TOTALLYRC]

thanks for the quick reply. Your analysis appears correct. I am just wondering if the .2 lead screw tackles the higher torque/ poor high speed better, thus it might be a cheaper solution than a power suppy-controller combo. My working travel is relatively short.

thanks again.
tc

Without upsetting you or anyone else, what you have is a case of mismatched components. not enough voltage for the motors, motors that are in reality too large for the application. And so on.

That said, it all depends on how fast you have to go. If 60 ipm is all it will go now and you go to the .2 screws, figure maybe 100ipm reliably. If that is fast enough, and the screws are a bolt in, that may be the best course of action and probably the best bang for the buck.

If you need to go faster, you really need to look at the whole picture and decide how much you want to spend.

I don't know how fast you need to go to cut balsa cleanly, but I AM SURE SOMEBODY DOES.


Mike.



I

[High Seas]

Try a multi-start screw - http://www.cnczone.com/forums/archiv...p/t-40007.html
A short posting - maybe search the CNCZone for more details.
Jim

[ger21]

Probably a resonance issue. Switching to Gecko's would probably help, but the 10 tpi screw isn't helping you either. If you have dual shaft steppers, try making some dampers, which may also help a lot.

[greenene]

I am curious about the mismatched steppers, as you point out. Can any one suggest appropriate "smaller" steppers in order to increase the speed?

It clearly is a better choice than changing lead screws...
thanks
tc

[TOTALLYRC]

Since you mentioned Keling, both of these would give more top end speed with less low end torque. Since you are cutting balsa primarily, I think they would work well.
Hopefully somebody else will chime in with their recomendations.

KL23H276-28-4B (1/4" Dual Shaft with flat ) 282 oz-in. Price: $39

KL23H2100-30-4B (3/8” Dual shaft with a flat) 382 oz-in Price: $49

To find a motors max voltage the formula is sqrtmh * 32 = max volts.
This is for square body motors only and square is what you want.

The 425's that you have are ~82v max and these others are ~60v max so they will be a lot closer to the power supplies voltage. = more speed. Plus smaller motors have their torque drop off less as they go faster.

If you search around the zone, you can get a feel for what others are using for similar sized machines.

[greenene]

Thanks, guys. The motor suggestions as well as dampers have really got me going.

I will look into both.
tc

[TOTALLYRC]

Dampers are real cheap and easy to implement. I would try them first as what do you have to loose? and they will take a couple of hours to make and may give you the speed you need. The "better" drives have mid band instability compensation built in to the electronics and don't have the resonance issues that you are having. That being said, since you already have the drives, I think the dampeners are worth a try.
If you try dampeners, let me know how you make out. I would like to try them on my taig, but I am in the middle of too many things to do it right now.

Mike.