Cowboy Analog Servo Motor Modifications?

[BDAZ]

This is the final configuration I have come up with. A slight turn of the knob (with the pedal fully depressed) will run at around 16 SPM and fully turned counter clock wise the maximum will be will be 150 SPM. This is a range I am completely happy with.

If there is any interest I can order a bunch of jumpers, resistors and potentiometers so you can just swap out the existing pot. I will be putting shrink tubing on the exposed parts, this is just to show what it looks like. If you are handy with a soldering iron you need:

1 x 100k 1/2 watt Log (or Audio) pot with a 1/8th split shaft +-$2.00

1 x 10K 1/2 watt Resistor +- $0.25

1 x JST 2-Pin M+F Wired PCB Panel Battery Connector,JC2 +- $0.50

I'll be sending one to Cowboy Bob on Monday and he can try it and see if it's worth the effort.

The mod involves removing the 4 screws on the motor housing plus loosing the pully cover and allowing the housing to drop free. Carefully pull the connector that runs from the speed control to the board. I believe it is marked JP2. Pull the knob off the pot and then loosen the nut and remove the pot from the cover. Plug in the new connector noting that the ribs go into the slot on the connector. Push in firmly, replace the pot and turn fully clockwise. Replace the knob so it indicates 0. Replace the housing and reinstall the 4 screws then re-tighten the pulley cover and you are ready to sew.

Excuse the crappy soldering but I was in a rush to get this done and back to sewing!

Cya!

Bob

Edited June 15, 2014 by BDAZ

[Wizcrafts]

Bob;

Will your pot and resistor mod plug into my rotary switch on my FS550s? Or, would it replace the switch completely?

Does this extend the slow speed below stock and still have enough torque to turn the machine over at under 60 rpm (at the motor)?

Right now my FS 550, attached to a long body Singer 139 walking foot machine, bottoms out at 1 stitch per second, with 2.5:1 gear reduction from motor to flywheel.

I cannot give up my top speed. Whatever mod I might use, it must still allow full speed when needed (3500 rpm?).

[BDAZ]

Let me know what the "switch" says. It should be plug and play. Look at the connector where the switch plugs into the board.

Cya!

Bob

[Wizcrafts]

I will do that next time I go into the shop.

[BDAZ]

This mod will not change the performance of the motor, just allows a more accurate control of the maximum speed.

Do you have to turn the switch all the way to achieve full speed or does it happen in the first 25%, 50% or 75%?

Based on that answer it would be possible to substitute a control that has more control in the lower speed but will still give you the maximum you need.

What is the maximum speed in SPM?

Cya

Bob!

[Wizcrafts]

The changes are noticeable for each click of the switch. That is, until the last three, which do nothing more to increase the speed. The switch has been wired in backwards, with higher speeds counterclockwise and the lowest at full clockwise. The maximum driven speed at the machine would be about 1400 spm, or 23 per second, which is too fast for the machine. I get this by dividing the maximum rpm, which I think is about 3600, by 2.5, which is the motor to machine pulley ratio.

My actual maximum sewing speed used would be about 10 to 12 stitches per second (under 800/minute), on long zippers or hem lines. I guess a top motor speed of 1800 would do just fine for me on this machine. The slowest speed I currently get is ~1.5 stitches per second (thin pouches, wallets, phone cases and patches). I would like to be able to get 1/2 stitch per second, steady pace, for precision sewing around curves and shapes on motorcycle patches. Right now I single stitch around these shapes, or hand wheel through them. Taking my hand off the work loses control over the vest.

My vest patch machine is a 20" body Singer 139w101, compound feed, walking foot machine, with a 4.5" diameter machine pulley. The Family Sew motor has a 2" pulley.

Edited June 15, 2014 by Wizcrafts

[BDAZ]

I am guessing that a log pot of the same or slightly lower value would work much better than the switched resistor array you currently have since it's not a continuous range of resistance.

With your foot on the pedal, how many clicks does it take to start the motor?

Cya!

Bob

[Wizcrafts]

I am guessing that a log pot of the same or slightly lower value would work much better than the switched resistor array you currently have since it's not a continuous range of resistance.

With your foot on the pedal, how many clicks does it take to start the motor?

Cya!

Bob

The motor starts at the slowest switch setting (350 rpm), once the brake is released. The pedal has a good range of speed control, from just over 1, up to about 2.33 stitches per second. I only use that setting on biker patches and phone/pistol cases. It is way too slow for anything else I do on that machine. The brake is needed to stop the machine from over-sewing on 10 to 15 sps jobs.

[BDAZ]

Since it is a switch with each step setting a specific resistance rather than a continuous sweep, it it possible that the minimum resistance available is too high to produce the slower setting you desire. The minimum required to get the machine to move is around 12K ohms so I place a 10K resistor in line which then means the slightest resistance added by the pot will get the motor started. Since it is a log pot, a larger movement of the control is needed to make smaller increases in resistance at the lower end and then towards the middle of the resistance range it evens up.

With the current set up on the 3200 as delivered from Toledo, I max out at around 150 SPM. I am guessing that the stock pot would double that, but I have never timed it.

So from the above you may be able to calculate what your maximum speed would be with the Bob mod as described above. Plan B would be to replace the switch with a 200K potentiometer LOG (assuming that's your maximum value of the switch) with a 10K om resistor in series. That should give you greater control from 0-25 SPM but still allow full tilt.

If it were me I would note what the resistance of the switch on the 4th detent before the last and that is the maximum resistance you need. Since I have no idea what the resistance of each detente is, tough to make any recommendations.

Best idea would be to pull the switch and then using an ohm meter, log each detente and graph it.

Cya!

Bob

[Wizcrafts]

Thanks Bob for your input.

Note; on my CB4500, with the Family Sew motor, with its 2" pulley, feeding a 3:1 speed reducer, up to the machine pulley, for a total reduction of 9:1, there is no need to modify the pot or switch in the slightest. I already can sew at the speed of grass growing. Setting the switch to the slowest speed and pressing the pedal to the metal yields a steady top speed of one stitch per second. Even if I move the top speed position well up there, the slow speeds are still easy to attain.

[BDAZ]

I recently received a 50K logrithmic pot which I installed with a 10K resistor. The new pot will give a maximum of around 60 SPM with the knob turned all the way counter clockwise and it is easy to set any maximum speed in between. I have used it for a few days and it may be just a tad slow but the lower speeds are perfect for intricate stitching. It is very easy to set and repeat the exact maximum speed I want and the magnet mod gives me full control on the pedal from just barely moving to up to 60 SPM.

I am thinking of installing a second switch with and extra 50K-100K that will kit it into fast mode for belts, etc.

I am thrilled with these mods and I think they enhance performance significantly for next to no cost.

Cya!

Bob

[Severase]

Does anyone know where I can see a tutorial about setting up my servo motor? Well assembling it!!!