Cobra Class 4

[ChimeraKennels]

How about putting in a "stop" underneath the peddle to prevent overtravel...like they do on some target shooting triggers?

[particle]

The overtravel isn't really a problem - it's the fact that the servo motor's switch doesn't utilize all that overtravel to increase usable range of motion for better speed control. The only real solution is to A) modify the switch's light blocking blade and risk ruining it completely - and it may not have any effect at all or buy a new motor with a better (less sensitive, more range of motion) servo/actuator switch.

[Trox]

I have the same motor in 220 volts and a range of other motors on my nine sewing machines. This is a low priced motor and I will not compare to my high priced Efka dc motor. The motor is very strong; however, it is a bit sensitive on the pedal. Be sure to set up the “low speed starting sewing setup” (the time the motor use to reach full speed, the adjusted max speed) it ranges from “1” to “9“, “9” being the slowest start up time. The default startup time is “6”, it is much better on “9”.

If you have a speed reducer, be sure you do not have too much belt tension. Too much belt tension will make the machine hard to turn by hand, and the motor will need more power to start. Then again be more “sensitive” on low speed. The first generation low-priced servomotors were often too weak in power. I guess that was an issue for changing to an other design. If I had to choose between a motor too weak or to sensitive, I would choose the last one. You cannot get a motor like an Efka for 145 $, if you could then Efka would be out of business. This way we will be able to get a complete sewing machine for a reasonable price. I am sure that the Chinese makes 441 clones much better than they make hi-tech servomotors. I think that an Efka dc 1550 will replace both the low-end servo and the reducer. It is a perfect motor, only one V-belt, strong enough without a speed reducer. The setup will be some hundred $ more, but not much. I think those Cobra/Cowboy machines deserve a high-end motor option.

Trox

[particle]

I'm curious why you like the "low speed starting sewing setup" - can you explain what purpose you see in it? I don't know how yours works, but mine, no matter if it's set at 1 or 9, will sew very slowly, then instantly jump to whatever max speed the motor is set to run at. It's not a gradual speed increase. My fear with using the slow start option is that you don't know how far you've pushed the pedal down, and if you've pushed too far and your speed is too high, it'll take off and stitch off your line, beyond you line, through your thumb, etc.

Perhaps if the motor slowly ramped up to the max programmed speed, I'd see more benefit to it. Otherwise, I just don't see the point in it.

[Trox]

Did I say I liked the” low speed starting sewing setup”?

No, I said; it is the time the motor uses from 0 rpm to the rpm you choose to sew on. Of course, it is much less sensitive on 9 than on 1. It is the motors response time, the acceleration time of the motor. Let say you set the motor to max 100 rpm and the start up time to 9; it will use more time from you push the pedal to it reach the desired speed, than if you set the startup time to 1. So that is the purpose, it will not jump as quickly with longer startup time. Forget about the name, it is a result of Google translates, I do not say it is good, but that is the purpose. Keep your hand away from the needle at any time; it goes for every sewing machine with the motor switched on.

I'm curious why you like the "low speed starting sewing setup" - can you explain what purpose you see in it? I don't know how yours works, but mine, no matter if it's set at 1 or 9, will sew very slowly, then instantly jump to whatever max speed the motor is set to run at. It's not a gradual speed increase. My fear with using the slow start option is that you don't know how far you've pushed the pedal down, and if you've pushed too far and your speed is too high, it'll take off and stitch off your line, beyond you line, through your thumb, etc.

Perhaps if the motor slowly ramped up to the max programmed speed, I'd see more benefit to it. Otherwise, I just don't see the point in it.

[particle]

Wow - I wasn't trying to start an argument.... You said "Be sure to set up the “low speed starting sewing setup...The default startup time is “6”, it is much better on “9” - I assumed that meant you liked it set at 9, which is the maximum & longest delay on my machine. Sorry if I misunderstood.

I prefer to push the pedal down and have the machine instantly do exactly what I tell it to, instead of hesitating for a moment and then jumping to max speed. With that pause, it's hard to know how far you actually pushed the pedal down and the motor may run faster than expected. That pretty much negates any variability that is (or should be) built into the foot pedal. As a result, it forces the user to run the machine at a lower max speed since it's so hard to control the foot pedal. I'm not sure I've seen anyone actually come up with a good reason of why that is a good feature. If I'm sitting in traffic and I push my gas pedal down on the car, I expect it to go as fast or as slow as I tell it, not crawl for a moment, then suddenly lurch ahead and slam into the car in front of me.

Obviously I don't sew with my fingers in front of the needle.... I was merely making a point that accidents are more likely to happen when machines act unpredictably.

[Rising Sun Leather Co]

Ok then. Lets change gears here to lighten things up. I wasn't going to get involved with this one because of lack of experience with any sewing machine, especially a heavy leather stitcher, but here goes.

This is going back to the"bumps" on the back side of the leather issue. First off, up until today all the stitching I've done,(and it's been a lot) has been by hand. I do have a tippmann boss stitcher(which I did use today). When I first got the machine it was used and had some issues with it. It didn't feed the leather proper, it missed stitches, the stitch length wasn't consistent, it scratched up the backside of the leather, and it left those "bumps". I sent it to tippmann industrial, where they completely restored the machine and sent it back to me. When I received the machine, I couldn't wait to use it. Pulled it out of the box, set it up, grabbed some leather, and away I went. Well, let me tell you... It's just not that easy. The machine was repaired and yet it was still not stitcing the way it should be(this was my error this time). And it was leaving the "bumps" still. I put it away and went back to stitching by hand. Later that week I went to my friends, who happens to have a Cobra 4. He let me play with it and I decided I have to get one of these(so I have one on order). Anyway, when I was done using his machine, I looked at the bottom stitches, and guess what, the were there. Today, I took my Boss back out of the box and played with it, adjusting the tension settings and stitch lengths untill I got it working so I was happy with it. I made a holster and belt with bullet loops and it worked perfectly(didn't miss any stitches, evenly spaced) and guess what... No "bumps". Yep I said NO BUMPS.

The secret is to not take short cuts. When I stitch by hand I put a stitching groove on the front and back pieces of leather (this makes the stitches level with the surface of the leather so they won't get rubbed and worn out.(i think it adds a very professional touch). Anyway, I did the same thing before I used the Boss. No Bumps, and you can't feel the stitches.

Problem solved, use stitch grooves. Also, I am selling my Boss for $1100 + $30 for shipping.(to help pay for my cobra 4) I will be putting it on ebay monday or tuesday, so if your interested send me a P.M. before then.

Thanks for taking the time to read and I hope this helps everyone.

Here is the rig I made. Another satisfied customer. Sorry, I didn't take any close ups of the back because I wasn't going to get involved... But trust me, "no bumps".

[ChimeraKennels]

Just a note...but when we drive our vehicles and push the accelerator, a vehicle doesn't instantly go 65 mph. It works up to that speed. Very few of us actually push the peddle the exact distance downward to go our desired speed. Most of us push the peddle to get going and adjust our peddle pressure as needed to go faster or go slower...The tires don't always match the throttle pressure and there is a delay to respond to such pressure. I don't see the delay as a problem as long as the transition is smooth (not overly sensitive) in terms of safety (or smooth in terms of sewing machines).

Is the hesitation a reduction in acceleration during transition (a reduction or sensitivity) or just a delayed time response?

I compare sewing leather to driving on ice. You can't afford to puncture a hole where you don't want one since you can't remove an accidental hole. The perfect ice driving vehicle (leather stitcher) wouldn't take off fast like the perfect dragster (factory upholstery machine). Two different things. One ideal is very fast and very responsive while the other ideal is delayed and not sensitive and much less responsive. The latter may still be able to go fast, but it give you time to accommodate the acceleration to prepare for it...so you don't have an accident.

Anyway, just the thoughts of a rookie here.

Edited June 2, 2012 by ChimeraKennels

[particle]

Okay, seriously? It's an example - trying to help others understand what's going on here with these motors.

The delay is an instant transition from a forced crawl that occurs for a user pre-programmed amount of time, then a sudden and instant jump to max user programmed speed, unless you are lucky enough to have not pressed down a fraction of an inch too far.

[ChimeraKennels]

I don't know if you misunderstood me or not. When I stated "rookie here," I was referring to me...not you.

Eric, what ever you are doing, I would say you are doing it right. I went and looked at your work, and it looks exceptional. Keep up the good work.