Servo Motor Mod: Diy Easier Speed Control

[Wizcrafts]

My motor is a TN-411 - that's all it says. Not sure what brand that is.

It's a WhoFlungDung motor.

[Iron Pounder]

I have sent this to a few guys that have had trouble with the lack of adjustment. Years ago I worked as a tech in the printing industry. We had these optical switches all over small offset press. We had the same lack of adjustment problem and made a new part of out a frisbee. It was stiff enough to last and when you thin it down enough light will start to pass through it. It is a trial and error type thing for sure but we got it lined out. Of course the factory said they didn't have any problems with other machines around the world (this is THE standard answer you always get). The following year I was at a training class and someone brought the very problem up and all the sudden the room lit up with everyone having the same problem. About 1 month late the factory had to admit it and sent out an updated complete assembly.

It's to bad such a good machine (from what a saw last week and have always heard would have such a flaw. I guess it is at least operator fixable, but if it is operator fixable it is dealer fixable if they wanted to. If this was a car it would be recalled for safety reasons, as I bet some lawyer could have a field day with it. Think if your car pedal worked this way.

[particle]

I gave it another try a few minutes ago - this time with the post-it-note method. I gotta say - this might be the best method yet. It's very easy to adjust the spacing of the pieces of paper. I might try again with a bit tighter spacing and more layers. With this version, I can only utilize 1-22 out of the max speed of 40. I'll NEVER go that fast with this machine, but it's not working 100% so I'm not ready to give up yet. This spacing is roughly 1/16" spacing - it probably needs to be 1 ever 1/32" since I'm already hitting the max range of travel with this size/spacing. A darker paper color might help too, which will change the spacing too....

Edited July 29, 2012 by particle

[particle]

I shot a little video last night of me sewing one of my pancake holsters using the post-it-note mod shown in my previous post above. What you can't see in this video is that I now have FULL use of the entire range of motion on my foot pedal to control the speed. Granted, with this particular color of paper an the amount of layers I'm using, I can't make full range of the maximum speed of the machine. But, 22-23 (out of 40) is still pretty fast for this type of work - much faster than I need to be using. Honestly, if I was able to utilize the entire speed range from 1-40, the pedal would be twice as sensitive as it is now (with the post-it-note mod installed). So, even though I can't use the full range of speed, the pedal is effectively twice as controllable since it's half as sensitive as it "should" be (to utilize the entire speed range of 1-40 over the same foot pedal range of motion).

[UncleGeorge]

Very nice! Tried it, works as described. Used yellow post-its. Took 3 tries to get it like a wanted it. Maybe 30 minutes total messin' with it. I totally encased my post-its with scotch tape to protect it from heat and humidity and such, then adhered to arm. Seems like manufacturers could come up with somethin simple like this as an upgrade. My wife who is a seamstress and has several machines, never liked mine because of the speed control. She says that it is more like it ought to be now. Thanks for info and videos. Uncle George

[SWFLholsters]

Very nice! Tried it, works as described. Used yellow post-its. Took 3 tries to get it like a wanted it. Maybe 30 minutes total messin' with it.

Glad to hear it worked.

What motor are you using?

[SWFLholsters]

I shot a little video last night of me sewing one of my pancake holsters using the post-it-note mod shown in my previous post above.

Eric, great video, I love your holster work and really appreciate your video how-to's, thanks big time for sharing.

I can't wait to add a Cobra 4 to the holster tool box.

[UncleGeorge]

Glad to hear it worked.

What motor are you using?

Year and a half old Cobra 4. TN 421. On my machine I had about 1/8 inch actuator arm travel from low to high speed. The actuating arm is a little different shape than in the videos and it is not removable. It has a set screw keeping the arm tight to the pivot shaft but I noticed that there is a pin that is not removable that keeps the arm from being lifted up off the pivot shaft. I didn't try to remove it as there is no need to remove it. There's a small "L" shaped metal plate attached to the arm with two screws. The "L" shaped plate is removable and adjustable with these screws. One end of the "L" shaped plate is the part that moves under the light beam. I taped the post-its to the "L" shaped metal plate. Sorry no time for pics and better detailed explanation. I think anyone who opens theirs up will see how to do it. Outside cover comes off easy with just 3 screws instead of 4. It is not mechanically connected to anything on the inside of the motor case, just 3 wires attached to the actuator that have enough slack in them and don't get in the way. Very easy. Much more control now. I loved this machine before the modification as I had gotten used to the speed control and it has been great!. It's even better now.

[MADMAX22]

This is a great idea. Guess I stopped back in at the right time.

Was thinking would a piece of plexi that had a gradient color work as well? Thinking it would be a little tougher and would have very fine control. Gonna have to play with this.

[particle]

I tried transparency film with a printed gradient. Barely engaged the motor at the darkest point. Printed another one, but printed on both sides to make it even darker. Not much change. Switched to vellum. Not much better. I wanted to try a spray paint gradient but didn't have any on hand. It takes quite a bit of light blockage before the motor activates at all.

Edited August 5, 2012 by particle