Question For Cobra Owners

[VanDutch]

Hope you can help me in setting my servo motor speeds for max torque. I find that if I am sewing slowly through thicker material the motor stalls and I have to manually turn the wheel a fraction. My motor settings are.

Speed = 1 (1-9 setting)

RPM = 10 (1-40 setting)

There is a speed reducer installed.

What settings do you use?

cheers

Frans

[VanDutch]

No cobra users out there?

[Northmount]

The slower a motor turns, the lower the torque it produces. To get the punching power (torque) you need for heavier leather, the speed reduction has to come from the speed reducer. Do you have a stepped pulley set (more than 2 belt grooves)? If so make sure the motor belt is in the largest diameter groove, and the machine belt is in the smallest diameter groove.

Tom

[rmr]

Frans

I had the same problem a few years back- was very frustrating at first- - I posted on here and several guys including Steve at Cobra contacted me and recommended I double check the bolt holding the pulley wheel to its shaft- as it was probably slightly loose and had allow3d the pulley wheel to shift upwards ever so slightly resulting in the tension on the belt to be reduced and causing the needle to stop/stall in the middle of thick layers of leather.

So I checked it out when I got home from work that night- they were spot on- tightened up the bolt - after pulling the pulley wheel assembly downward about 1/4 " to place more tension on the belt- never had the problem since then

RMR

[Greystone]

I have not had the problem but I've also been very limited in my usage and

limited to mostly softer leather bridle, chromexcel , and upholstery,

But at times up to 4-5 layers of, 5-6 an-8-9 oz and no issue,

LOVE my KING cobra

[Trox]

Hi Frans, do you have the EPS motor or the regular servo motor without needle position (Called EPS by Cobra). If you have the EPS and your machine flywheel is loose the machine will stall, because of the position sensor installed on it. It will send faulty signals to the motor to stop. Otherwise, I would need to know about your sewing thickness and thread size etc. to see if its normal or not. This motor should be powerful enough for this machine.

Good luck

Tor

[Cobra Steve]

Hi VanDutch,

The setting that you refer to as SPEED has nothing to do with speed at all. Actually it is a setting that can be used to cause a 'delay' from the time to demand power until the motor actually starts turning. On some sewing applications (not leather sewing!) some operators prefer a slight delay and that is why we have incorporated this electronic option on our motors. Your choices for this setting range from 0 - 9. You should have yours set to 0. (Hold the down button until the display reads 5.0 and then press the UP buttom once to get into the 5.1 programming mode. Press the down button once and your setting will appear on the readout. If you are set at 1 - press the down button one more time so that the display reads 0. Wait for the motor to store that setting - about 5 seconds.

Now on to your speed (RPM) setting - I suggest you move the Max RPM from 10 up to 12.

Our motors are 600 Watts or 8.3 HP - more than enough to sew up to 7/8" leather smoothly. I would check both your V-Belts to ensure they are not slipping - it sounds like at least one of them are slipping. And while you are checking everything, make sure the 'pointed' bolt on your handwheel is firmly tightened in to the groove on the main shaft of your Cobra. Then firmly tighen the other bolt as well.

If you have any other questions, please contact us.

Thanks

Steve

[Greystone]

KUDO'S n SHOUT OUT to

Steve and LMC

[VanDutch]

The slower a motor turns, the lower the torque it produces. To get the punching power (torque) you need for heavier leather, the speed reduction has to come from the speed reducer. Do you have a stepped pulley set (more than 2 belt grooves)? If so make sure the motor belt is in the largest diameter groove, and the machine belt is in the smallest diameter groove.

Tom

Hi Tom.. I have worked a lots with Servos/Stepper motors on CNC machines and the feature of these motors is that they have Max torque at any RPM range. They don't use inertia like an induction motor does.

Hi Frans, do you have the EPS motor or the regular servo motor without needle position (Called EPS by Cobra). If you have the EPS and your machine flywheel is loose the machine will stall, because of the position sensor installed on it. It will send faulty signals to the motor to stop. Otherwise, I would need to know about your sewing thickness and thread size etc. to see if its normal or not. This motor should be powerful enough for this machine.

Good luck

Tor

Hi Tor.

Yes I have the EPS motor. I will check the flywheel. Thread size is 277 and the material thickness is 8-10mm. I only have issues at really slow speeds like corners on gussets. Normal sewing it is punching through no problems.

[VanDutch]

I must say that I have had great support and communication from Greg (Dealer) Qld Sewing Machines. Yesterday I delved further and decided to try something to eliminate belts etc.

I removed the flywheel belt and the needle and free-wheeled the machine.. I found that after a number of turns the wheel grabbed(stopped) and required backing it a fraction before it would allow me to spin forward again. This is def not normal. Any ideas what this might be?