particle Report post Posted May 21, 2012 So, I received my new Cobra Class 4 recently and have been playing around with it a bit. One thing that has me a bit annoyed is the lack of easy variation in the speed when you press the foot pedal. Yes, I'm well aware you can adjust the max speed on the motor. When I press the foot pedal, I expect it to utilize at least a fair portion of the travel of the foot pedal to vary the speed. Mine is so sensitive, all the speed is literally controlled in probably less than 1/8th of an inch of travel. Is this normal? It might as well be a clutch motor at this point! The actual lever on the motor has a nice range of movement. Sadly, most of that movement does absolutely nothing to affect the speed. And what's the point of the low-speed start mode? Why would you want the machine to start slowly, then surprise you by ripping away at full-speed and ruin your work? The only purpose I could see is if you just keep tapping on the pedal to continually make the machine crawl at low-speed until you are ready to go full-speed. Maybe I'm missing something? Here is a video I shot that shows what I'm talking about. Please ignore my wife's runner's feet. It was an impromptu filming. She just ran a half marathon and lost a couple toe nails... http://youtu.be/IsxufcVvKdc Quote Share this post Link to post Share on other sites
Luke Hatley Report post Posted May 21, 2012 (edited) Look at the pulley on the motor, if it is 3" or larger replace it with a 2" pulley. I had to do that on mine. Also there are 2 rods with an adjustment clamp on mine i had to lengethen mine for more travel for the foot pedel. Edited May 21, 2012 by Luke Hatley Quote Share this post Link to post Share on other sites
gringobill Report post Posted May 21, 2012 That's odd that your machine is doing that. I have one that's coming up on two years old and it is not that touchy. I have to push the pedal down about 1/4 to 1/3 of it's stroke before the motor starts moving. I'm wondering if it has somthing to do with the length of the chain between the pedal and the lever, it may be too tight and needs some slack in it, Just a thought? My chain has quite a bit of slack in it and the motor is pretty controlable. Quote Share this post Link to post Share on other sites
gringobill Report post Posted May 21, 2012 I just watched your video and noticed the noise the motor is making, mine does not do that. It sounds like it is really winding up with very little pedal movement. Something sure seems to be out of adjustment. What speed do you have your motor set for? You may need to lower the max speed way down. I'm not where I can look at the speed on mine right now, but it's maximum speed is set pretty slow so I have more control. When I want to adjust my speed, I unthread the top of the machine so I can watch how fast the needle moves when I'm adjusting the speed. The only complaint have about this machine is IMHO adjusting the speed is kind of unhandy. The machine has to be running to adjust the speed up or down and for me to do that I have to get on my hands and knees and push the pedal with my left hand and adjust the speed control with my right. Obviously I can't see what's going on above very well. However since your wife will help you making it a two person job would simplify it a whole lot. Quote Share this post Link to post Share on other sites
Northmount Report post Posted May 21, 2012 The arm on the motor usually has 2 or 3 holes in it for the foot pedal connection. Make sure it is in the hole furthest from the shaft it pivots on so it has the longest arc to travel through. CTG Quote Share this post Link to post Share on other sites
particle Report post Posted May 21, 2012 I should have mentioned this, but forgot. When I filmed the video, I had the motor set at max speed - I was winding a bobbin. But, regardless of the maximum set speed, the lack of control in the foot pedal pressure makes the higher speeds useless. The whole point of the servo motor is to provide great control in speed when compared to a clutch motor. When you press the clutch motor's pedal down, once the clutch grabs, the machine takes off. It's very hard to control the speed. That's the same feeling I'm getting from this particular servo motor. I expected more control in the foot pedal. I should be able to use max speed on the motor if I want to, but also have access to the slower speeds by applying less pressure to the foot pedal. That's just not the case - maybe I expected too much? Quote Share this post Link to post Share on other sites
particle Report post Posted May 21, 2012 The arm on the motor usually has 2 or 3 holes in it for the foot pedal connection. Make sure it is in the hole furthest from the shaft it pivots on so it has the longest arc to travel through. CTG Done - that was the fist thing I changed when I assembled the machine. It came on the middle hole, and I moved it to the furthest out. Along that line - I fabricated a longer 12" arm out of a bar of aluminum I had laying around. I put holes every inch, and bolted it to the existing lever on the motor. This helped with the variation quite a bit, but added too much weight and the springs couldn't overcome it so the machine wouldn't shut off I don't feel like adding new springs to compensate for the added weight just yet. I moved it to around 6" and that fixed the shut-off problem and gave me more control in speed than stock configuration, but I removed it until I could talk with Kevin today to see if I just got a bad motor. Quote Share this post Link to post Share on other sites
Gregg From Keystone Sewing Report post Posted May 21, 2012 A 'Slow Start" option that is usually adjustable is great to allow the first few stitches to catch up, so they to do become lose or get caught back into the sewing mechanism. It's a really useful option, IMO, but you can of course turn this feature off if you like. As for the power band, I do hear you, some have a very limited range of variable speed, as in you can go fast to slow with good control, as long as you do it withing a short range of arm movement, where having the flexibility of a larger 'power band' would make life a lot easier for the operator. This is a concern with a lot of these servo motors coming out. Quote Share this post Link to post Share on other sites
particle Report post Posted May 21, 2012 So the slow start feature helps to minimize initial stitch problems? That's interesting and good to know - the manual doesn't say anything about that as far as I can recall so I really had no idea what the benefit of the feature was. Quote Share this post Link to post Share on other sites
Gregg From Keystone Sewing Report post Posted May 21, 2012 So the slow start feature helps to minimize initial stitch problems? That's interesting and good to know - the manual doesn't say anything about that as far as I can recall so I really had no idea what the benefit of the feature was. If you have the documentation that I'm thinking you have, then it's probally pretty limited for sure. 'Slow Start' or AKA 'Soft Start' is usually a feature found on more expesive Ho Hsing, Mitsubishi, or Efka motors, so having this option on a less expensive motor is a pretty nice feature. Quote Share this post Link to post Share on other sites
particle Report post Posted May 21, 2012 Probably the same documentation you're thinking. And the fact that it's poorly translated doesn't help matters at all! Quote Share this post Link to post Share on other sites
particle Report post Posted May 21, 2012 If you have the documentation that I'm thinking you have, then it's probally pretty limited for sure. 'Slow Start' or AKA 'Soft Start' is usually a feature found on more expesive Ho Hsing, Mitsubishi, or Efka motors, so having this option on a less expensive motor is a pretty nice feature. Out of curiosity - you mention 'more expensive' motors. Do you have any experience with those motors? Do those motors have any better speed control? Second question - how much more expensive are we talking? Quote Share this post Link to post Share on other sites
Gregg From Keystone Sewing Report post Posted May 21, 2012 Out of curiosity - you mention 'more expensive' motors. Do you have any experience with those motors? Do those motors have any better speed control? Second question - how much more expensive are we talking? Yes, sure we do; We stock, supply, and install Efka, Mitsubishi, and Ho Hsing motors of all types. A very nice option is the Ho Hsing 'MJ' series needle positioner motor, seen here on our servo motor page; Click for Ho Hsing MJ motor Thanks for asking! Quote Share this post Link to post Share on other sites
Cobra Tom Report post Posted May 21, 2012 Dear particle, My name is Tom. I work for Leather Machine Co. The motor is able to run at maximum speed (setting of 40), but for the COBRA Class 4, it should not be used above a setting of 10. The greater the maximum speed is set to, the faster it goes within that short distance that the actuating lever travels. E.g., If top speed=40, then 50% of max. foot pressure will still drive the machine at twice the max. recommended speed. Please fre-adjust the motor's max speed to a setting of 10 or less. I should have mentioned this, but forgot. When I filmed the video, I had the motor set at max speed - I was winding a bobbin. But, regardless of the maximum set speed, the lack of control in the foot pedal pressure makes the higher speeds useless. The whole point of the servo motor is to provide great control in speed when compared to a clutch motor. When you press the clutch motor's pedal down, once the clutch grabs, the machine takes off. It's very hard to control the speed. That's the same feeling I'm getting from this particular servo motor. I expected more control in the foot pedal. I should be able to use max speed on the motor if I want to, but also have access to the slower speeds by applying less pressure to the foot pedal. That's just not the case - maybe I expected too much? Quote Share this post Link to post Share on other sites
particle Report post Posted May 21, 2012 Dear particle, My name is Tom. I work for Leather Machine Co. The motor is able to run at maximum speed (setting of 40), but for the COBRA Class 4, it should not be used above a setting of 10. The greater the maximum speed is set to, the faster it goes within that short distance that the actuating lever travels. E.g., If top speed=40, then 50% of max. foot pressure will still drive the machine at twice the max. recommended speed. Please fre-adjust the motor's max speed to a setting of 10 or less. Good to know... Thanks for responding Tom. Regarding the actuating lever - did I get a dud motor, or do they all have a "hair trigger"? My lever (like I'm sure they all do) has quite a bit of travel, but an extremely small area of travel actually effects the operating speed. I was really expecting a greater/easier variation in speed when I press the pedal down, instead of essentially on/off with a slight twitch of the foot to feather the speed... Quote Share this post Link to post Share on other sites
Dallas Cowboy Report post Posted May 21, 2012 Eric-sounds like there should be some way for you to adjust it. Here is a video I found for ya showing what it should run like. Quote Share this post Link to post Share on other sites
RonDrake Report post Posted May 21, 2012 Dear particle, My name is Tom. I work for Leather Machine Co. The motor is able to run at maximum speed (setting of 40), but for the COBRA Class 4, it should not be used above a setting of 10. The greater the maximum speed is set to, the faster it goes within that short distance that the actuating lever travels. E.g., If top speed=40, then 50% of max. foot pressure will still drive the machine at twice the max. recommended speed. Please fre-adjust the motor's max speed to a setting of 10 or less. Quote Share this post Link to post Share on other sites
dbusarow Report post Posted May 21, 2012 Good to know... Thanks for responding Tom. Regarding the actuating lever - did I get a dud motor, or do they all have a "hair trigger"? My lever (like I'm sure they all do) has quite a bit of travel, but an extremely small area of travel actually effects the operating speed. I was really expecting a greater/easier variation in speed when I press the pedal down, instead of essentially on/off with a slight twitch of the foot to feather the speed... particle, My Cobra 4 acts the same way. All of the speed control is in the 1st 1/8" of travel of the arm. Steve did send me another motor to try and it's the same as the first. I figure that's just the way they are. I just adjusted max speed way down. Maybe after I've been using it a couple more years I'll be able to handle higher speeds. I've been thinking about ordering one of the Techsew servo motors and trying that. I'll take a look at Gregg's too. Dan Quote Share this post Link to post Share on other sites
particle Report post Posted May 21, 2012 (edited) Another forum member has been chatting with me today - I'll leave him nameless unless he wants to step into the conversation. He pulled his switch plate off to see what the speed control consisted of. It appears to be some sort of light-sensitive switch. An opaque blade passes over the light (seems to be an LED) as you rotate the lever. In theory, the light sensor would detect less and less light, providing gradual control of the speed. It's essentially an on/off switch with almost no fine-tune control via the lever. There unfortunately doesn't seem to be any way to adjust the switch's sensitivity, and replacing the servo motor with a same-kind motor would likely have no effect, unless the switch happened to work better. Edited May 21, 2012 by particle Quote Share this post Link to post Share on other sites
KAYAK45 Report post Posted May 21, 2012 Hey there! You might have a "runaway" motor. Send for and try another. I had a runaway and found out the speed adjustment just did'nt work. Try another one. The dealers are easy to work with. The chinease makers, maybe not so much. Quote Share this post Link to post Share on other sites
DDahl Report post Posted May 21, 2012 I've had similar issues with my cobra 4 and the servo for my Seiko flat bed. If you are brave and persistent you can significantly improve your low speed control. First, those servos generally make use of an optical sensor that is virtually an on and off device. This is because the light block and unblock acts SO suddenly (really bad engineering!). The trick is to force the light intensity (pass through to the detector) to change far more gradually. As you improve (slow down) this transition your servo control will dramatically improve. In my case, I found that adding a piece of paper (taped to the moving light blocker) could help do the trick. Just take a pencil and shade a gradient on the piece of paper so that it is the darkest where the light would first shine through the slot and then gradually lightens to no shading as the assembly is rotated. It may take several attempts on your part (paper, tape, and curses) but if you persist and learn from the effects you observe, you can desensitize the servo pretty much to your liking! Have Fun! Dave Quote Share this post Link to post Share on other sites
Dallas Cowboy Report post Posted May 21, 2012 What is cobra steve saying about this particle? Quote Share this post Link to post Share on other sites
particle Report post Posted May 22, 2012 That's interesting Dave - I might give that a try. Thought about a gradient filter as well for photography. Steve is on the road driving back from Sheridan. I'm not sure he was aware of the problem. I'll practice some more and maybe try the modification but want to make sure I don't void any motor warranties. Quote Share this post Link to post Share on other sites
Dallas Cowboy Report post Posted May 22, 2012 Have that sucker master by friday. LOL Quote Share this post Link to post Share on other sites
Big G Report post Posted May 26, 2012 Have that sucker master by friday. LOL when i received my cobra it was way out of time ,, steve walked me through timing it. took a little trial and error to get it right . mine doesnt have much variation in speed with the pedal , but i dont sew fast either. like you i was sewing on a tippmann. i was comfortable with a little more speed. hope you find a answer . i sew at around 600 rpm on holsters. little higher on belts i am sure steve will help you Quote Share this post Link to post Share on other sites
