Cobra Class 4

[Dallas Cowboy]

As I stated earlier. The machine is great and I will PROBABLY buy one. The motor was my main complaint not the actual sewing machine. I wasn't trying to start a fight with this thread. Instead I was trying to figure out why this motor acts like it does and to hopefully figure out a fix. But it looks like I have got a few ppl rialed up and that was not my intention

[Steven Kelley]

As I stated earlier. The machine is great and I will PROBABLY buy one. The motor was my main complaint not the actual sewing machine. I wasn't trying to start a fight with this thread. Instead I was trying to figure out why this motor acts like it does and to hopefully figure out a fix. But it looks like I have got a few ppl rialed up and that was not my intention

Don't let the motor stop you from buying one. They are fantastic machines. You can buy a replacement motor that has much better slow speed control for $100. I know replacing a motor is the last thing you want to do on a new machine, but in the grand scheme of things, especially if you are selling the stuff you make, it's nothing. Maybe you could get Steve or Bob to swap out the motor ahead of time. In many ways, I prefer sewing on my CB4500 rather than my Adler 205-370, and if I had to sell one, it would be the Adler.

[BondoBobCustomSaddles]

Don't let the motor stop you from buying one. They are fantastic machines. You can buy a replacement motor that has much better slow speed control for $100. I know replacing a motor is the last thing you want to do on a new machine, but in the grand scheme of things, especially if you are selling the stuff you make, it's nothing. Maybe you could get Steve or Bob to swap out the motor ahead of time. In many ways, I prefer sewing on my CB4500 rather than my Adler 205-370, and if I had to sell one, it would be the Adler.

That last sentence is a mouth full of words! I think it says it all.

Bob

[ChimeraKennels]

I saw it mentioned that you could attach and extended pull bar on the motor to make it more controllable/less sensitive...but in doing so it put too much weight on the motor's switch...

Well, There is more than one way to skin a cat. Most of the machines I have seen have the pulley attached to the peddle at the back of the peddle...the area that travels the furthest with each tiny change of foot angle.

Why not move the attachment on the foot peddle closer to the pivot/fulcrum point? This way, it wouldn't travel as fast as you change your foot angle, and doing so would give you more control without adding weight on the motor's switch.

Anyway, just an idea.

[particle]

I thought of that too. Unfortunately for me it won't work, but for someone else it might. I'm actually an amputee - I have a prosthetic right foot. I control the machine and raise the presser foot with my left foot, so my left foot needs the ability to slide from pedal to pedal. If I relocated the chain closer to the pivot point, my foot would hit the chain as I move from one pedal to the other. I also debated using a couple pulleys and a cable so I could run the cable along the base of the stand, then I talked myself out of it by thinking "this is a brand new machine that I just spent a couple thousand dollars on - I shouldn't have to (and don't want to) do this!".

Right now I'm keeping the machine set at a slower speed, around 7 or 8, just to make sure I avoid any accidents by going too fast. I'm getting better at controlling the speed, but I still might consider selling this motor and buying another one like Steven mentioned.

[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.

[Dallas Cowboy]

As I stated earlier, the bumps are not the main concern. The main concern for me and others was the lack of a full range of motion in the peddle. Yes the peddle moves quite a bit and has a travel range of about 3 inches or so. But the motor only uses about 1/4" of that range. Its not like the full control of a gas peddle in a car where the motor reacts to the entire range of the peddle. Instead this motor goes from zero to full blast all within a 1/4". It can be controlled by adjusting the max speed way down but it would be nice to be able to keep the max speed up and have a peddle range of motion that is much larger so you can creep along or haul butt depending on your needs.

[busted]

This is probably a foolish thought but why not put a speed reducer pulley on the machine. Restrict the machine to around 800spm or less if you want to. You will not loose the starting torque and you will control the range of speed. Just a thought. I made my own speed reducer 8"x 21/2" with a 3" on the motor. Works very good.

As I stated earlier, the bumps are not the main concern. The main concern for me and others was the lack of a full range of motion in the peddle. Yes the peddle moves quite a bit and has a travel range of about 3 inches or so. But the motor only uses about 1/4" of that range. Its not like the full control of a gas peddle in a car where the motor reacts to the entire range of the peddle. Instead this motor goes from zero to full blast all within a 1/4". It can be controlled by adjusting the max speed way down but it would be nice to be able to keep the max speed up and have a peddle range of motion that is much larger so you can creep along or haul butt depending on your needs.

[Wizcrafts]

This is probably a foolish thought but why not put a speed reducer pulley on the machine....

The topic is about a Cobra Class 4, which IS already equipped with a speed reducer pulley. My Cowboy CB4500 uses the same pulley (~3:1) reduction system. By the time the small output pulley feeds the large one on the flywheel, we are looking at anywhere from 8 to 9 times speed reduction and torque multiplication (depending on motor and flywheel pulley diameters).

I am hopeful that this discussion will lead to the development, or discovery of a better motor for these machines; one which won't drive the price up too much higher. There are already better motors available, but they cost a lot more than the servos included as standard equipment.

I can assure you that our dealers are discussing this matter and looking into possible alternatives. However, these new motors need to be tested under load for prolonged periods of time to ensure they can stand up to the heavy loads imposed by big machines sewing heavy leather, with big needles and thick thread.

[Ken Nelson]

This is probably a foolish thought but why not put a speed reducer pulley on the machine. Restrict the machine to around 800spm or less if you want to. You will not loose the starting torque and you will control the range of speed. Just a thought. I made my own speed reducer 8"x 21/2" with a 3" on the motor. Works very good.

The Class 4 Cobra comes with a speed reducer. As far as the content of this thread goes, I am astonished how many people here are expressing "Bright Ideas" that have no idea of what they are talking about. Seems "funny" that one or two people are having problems with a machine that the rest of us that own and use them get along great with. If you think you are having a problem with Cobra Steve's customer service, "you might bear in mind, that your are in a teeny-tiny minority!" I have been doing business with this man before he had his own company. In fact I have bought machines from him on 5 occasions totaling more than 5, some new-some used. I have had a couple of little problems with two of them and it has been taken care promptly and graciously. Once someone forgot to pack in some extra attachments I had ordered, one used machine had a motor problem, and I caused a couple of problems by letting Newby's sew on my machine. He didn't charge me for talking me through adjusting my mistakes either. As stated earlier, There is a definate learning curve on learning to sew on a sewing machine. Is it possible for the motor to be bad on the sewing machine in question, of course it is. Is it possible there is some user error here. Probably.

Is it possible that it is a combination of motor problem and operator error both? Could be. If you are using a household Singer sewing machine, you may well not know how to sew with a heavy leather sewing machine or stitcher. If you haven't sewn quite a lot on a heavy stitcher, you probably have a lot to learn.

Properly preparing your work to be sewn on a sewing machine is very important. Having your tensions set incorrectly can cause real problems. Not oiling your machine can cause problems as well as shortening the life of it. For an experienced sewing tech to say a machine is easy to sew on is different than saying doing a good job on a certain sewing machine is easy. I sew belts and skirts on saddles pretty slow. I know guys that burn through them 9-0 and theirs look as good as mine do. They started a long time ago when they were kids and do more of them than I do. Some machines are easier to sew with than others.

As far as the bumps on the bottom go, When I apprenticed under a pretty damn good saddlemaker, we dampened every stitch line in veg tan, tapped it to make it look just a little better. I still "set" the stitch line on about every project I sew. I was told," it is a matter of workmanship"

The motor set up on my Class 4 suits me just FINE! I don't need an upgrade. Just my 2 cents worth! Ken

Edited June 3, 2012 by Ken Nelson

[Dallas Cowboy]

The topic is about a Cobra Class 4, which IS already equipped with a speed reducer pulley. My Cowboy CB4500 uses the same pulley (~3:1) reduction system. By the time the small output pulley feeds the large one on the flywheel, we are looking at anywhere from 8 to 9 times speed reduction and torque multiplication (depending on motor and flywheel pulley diameters).

I am hopeful that this discussion will lead to the development, or discovery of a better motor for these machines; one which won't drive the price up too much higher. There are already better motors available, but they cost a lot more than the servos included as standard equipment.

I can assure you that our dealers are discussing this matter and looking into possible alternatives. However, these new motors need to be tested under load for prolonged periods of time to ensure they can stand up to the heavy loads imposed by big machines sewing heavy leather, with big needles and thick thread.

Yes!!! Thank you very much. I guess there are only a few people that are recognizing this issue.

[Ken Nelson]

Yes!!! Thank you very much. I guess there are only a few people that are recognizing this issue.

Maybe a few inexperienced people are blaming their lack of skill and experience on the equipment instead of learning how master their machine? When I started building saddles there were only clutch motors and we mastered sewing with them. I still have a couple of them on sewing machines I use. I get along fine with them but the students have HELL with them. Put a clutch motor on the machine in question, you may like it better! Ken

Edited June 3, 2012 by Ken Nelson

[Dallas Cowboy]

Really?? Wizcraft is an expert and he recognizes the issue.

[Cobra Steve]

Really?? Wizcraft is an expert and he recognizes the issue.

Hey Dallas. Ask Wizcraft what he did to his Class 4 at work to make his motor respond better. I think it was a minor adjustment. Steve

Edited June 3, 2012 by Cobra Steve

[Wizcrafts]

Ken brought up some really good points and suggestions. Newbies would do well to read through his post, #44, in this thread.

I never claimed to be an expert. I am just an experienced sewer-rebuilder, with some time as a worker bee in an industrial sewing machine store (Juki machines galore). I've put in hundreds of hours sewing everything from cloth, to vinyl, to leather. I have rebuilt many sewing machines, including two Union Lockstitch machines and gone through many machines that were supposed to sew leather, but did so poorly.

Until recently, all of my machines had clutch motors. I learned to feather the clutch to sew slowly and can still do so. I can adjust the action on a clutch motor to allow the range of free motion I prefer, where it releases the brake, but before it engages the drive. Most of the servo motors lack any such freewheeling/braking adjustments. The exception is the SewPro 500GR (now sold as the "Toledo Sew Slow") motors sold by Toledo Industrial Sewing Machines. I currently own two of those motors and have adjusted to behave much like clutch motors (release brake-engage slow-go quick-go fast). It's too bad they are (currently) a little under powered for a long arm 441 or Adler!

I have a Cowboy CB4500 at home and sew on a Cobra Class 4 at work. Both have common servo motors. Both are now into their second motor. I can feather the speed control on both motors to sew around one stitch per second, or one stitch at a time. One of the motors is touchier and drops out with a violent shake if I try to sew under one/second. This is a design quirk in the electronics that controls the unit. There is nothing that can be done, other than try to avoid that awkward spot. The other motor sews more slowly, about one every other second, then simply drops out with a whimper, rather than shaking the entire table and machine.

Both of the motors I use on these 441 machines are somewhat temperamental and have a rather limited range between just on and full on. Still, there is enough range of motion if I am careful with my foot and keep steady pressure on the floor pedal. Thankfully, I have a steady foot, but recognize that others may not be so fortunate. They will have a harder time controlling their motors than I do and their concerns need to be addressed.

Art once referred me to an SCR servo motor system that has tremendous torque at even the slowest speeds and Trox speaks highly about the Efka motors he uses. Both cost much more than the servo motors that ship on the 441 machines. Some of our dealers, or non-member dealers known to us, already stock higher-end servo motors, which they will happily sell to anybody. But, this topic is about the motors that are included as standard equipment on new machine purchases. I promise you that this is being worked on.

<rant>

They copy, but do not improve our machinery and electronics! Sometimes, their QC is lacking. Sometimes they use the cheapest marginally acceptable components, such as light sensors. They know who they are. Their alphabet is known in code-page as the Big 5.

</rant>

[Ken Nelson]

Really?? Wizcraft is an expert and he recognizes the issue.

I bow to your knowledge and experience. Apparently you are more knowledgable and a better leather craftsman than Troy West, Bill Gomer, Jessie Smith, Don Buttler, Pete Correll and Bob Klenda. If you are unfamiliar with the above gentleman, I would suggest you research their work and if you look on the Leathermachine Co website, you will see all of them own and endorse a Cobra Class 4. By the way, since you are an expert, how about posting some of your work. Ken