Motors?

[ChimeraKennels]

It is "Bonded Nylon" and is Pre-lubricated. I am going to sew a bit with the cover plate open to see if I can see what is going on as the needle thread goes around the bobbin case. I wonder if the tip of the hook is catching the thicker thread and nicking away at it? I am open to suggestions...but being this is a "motor thread"...I don't want to detract from this topic any further. I will put it on one of my other topics about the machine. Thanks.

Edited June 8, 2012 by ChimeraKennels

[Les No6]

Hi chimera

Single phase (domestic electrical supply) Clutch motors forsewing machines come in 2 pole and 4 pole high and low speed, the 4 pole hashalf the speed and twice the torque (shaft power=speed x torque), same withgearing you can trade speed for torque minus losses of course and you can gethigher gear ratios by using a counter shaft but at the expense of greaterlosses. Would a 1/2hp motor give you more control no, firstly your control inputis the clutch (torque converter) so your control depends on this component notthe motor, secondly, the motors are constant speed motors the torque orstrength as you see it is load dependant greater load greater the torque untilmaximum load at which point the motor stalls and torque falls to startingtorque (very little). Thirdly a 1/2 hp Chinese manufactured motor is more like a1/4hp motor from a quality manufacture like Brook Compton. As you can see youare not going to get more torque and may get a lower power motor. Clutch motorsare old simple technology efficient reliable, and dos everything a servo canwith a little skill, like everything, the main difference between clutch motorsis quality of manufacture, and quality cost but operates correctly last longer depreciatesless and much cheaper in the long run. Don’t worry about energy use when notusing the machine, as stated earlier torque is load dependant and the load onthe motor is just friction in the bearings heat losses are minimal as theresnot much current running through the windings so the motor draws little power(power=speedxtorque), they have high start up currents though so don’t turn offand on a lot.

A servo motor or more accurately servo controlled motor isan electronically controlled motor using feedback the purpose is to replacelarge heavy expensive motors with cheapersmaller lighter alternatives, increase efficiency by carrying out torque conversions electronically, eliminating mechanicaltorque converters i.e. gears pulleys counter shafts and torque smoothing flywheels with their associated losses. The servo controller is the importantclever bit NOT the motor, there are many cheap imports that claim to be servomotors but they are not (lack of feedback controller) these can beeasily identified by the use of oversized motors and gearing and or countershafts these are merely dc motors supplied via a variable current regulator sincetorque of a dc motor is directly proportional to input current its nothing morethan an electronic clutch and will not perform any better than a mechanicalclutch but at reduced efficiency. See attached video note the smaller cheepmotor outperforming the large motor which has a gear box incorporated, (don’t listento what the guys saying hes selling something!) Guess which is a real servo. With the benefit ofa university education in engineering I find the claims made by sellers of theseChinese so called servos highly dubious!

As to the maximum speed of your machine a google search shouldget you the manual and it will be in there you don’t want to go more than ¾ ofthat.

The problem with your machine sounds like a tension problemthe twist in the thread is usually caused by the tension being too tight itpushes the twist farther up the thread until it forms a knot. Start with theshuttle tension pull the thread from the shuttle it should pull out easy and smoothif it tends to judder the problems the bobbin, the tension in the shuttleshould be quite light. The problem couldalso be due to you trying to sew material too heavy for your machine foot liftis no measure of how heavy the machine will sew, to check the maximum weight itcan handle turn the fly wheel until the needle reaches its lowest point look atthe thread groove on the needle the top of this groove to needle plate is the absolutemaximum thickness it will handle, also check the needle size it may be toosmall for the gage of thread . Its good practice to oil all moving parts on asewing machine and the thread is a moving part use a light mineral oil, (babyoil is high grade mineral oil) it also keeps your needle and shuttle welloiled. Also check for burs on the shuttle and needle plate. Nylon not nicethread, try linen or polyester cotton.

[ChimeraKennels]

Thanks for the VERY detailed reply.