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About Gymnast

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    Applications for gymnastics. Repair of tarpaulin covers and with webbing. Rubber rope and terminations.

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    Sewing machines and ways to use them
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  1. As Uwe points out, there is a lot of specialized machines for shoemaking and boots. This is another kind of machine I find fascinating:
  2. Amann thread may also be possible. It is mostly used in Europe, and it is considered a very good quality brand. They got a dealer in Canada: https://www.amann.com/company/location-contacts/ Bonded polyester with good UV-properties is named Serabond: https://www.amann.com/products/product/serabond/ For tents or something to be more water resistant, you may choose Serafil WR.
  3. I have studied two manufacturers of gymnastics mats (or other foam shapes) with covers, that use this type of vinyl for with basic straight stitch seam. So it is mostly not for topstitching, and therefore appearance do not matter. I noticed the thread size and it is mostly Tex 90 or perhaps Tex 70 - so you are right. However I have also seen such mats after 10 to 20 years of use. Then the typical problem with the seems are that a thread is broken, so a seam starts to unravel. The other problem is, that the thread of the seam starts to cut through the vinyl. In both cases I should guess, that a thicker thread should increase lifetime.
  4. I have measured the thickness using a caliper, and the two layers are 1.1 mm in all. The thread size used here is Tex 135 polyester with a 140/22 needle. And yes, I agree, that it is easier to balance the stitch with more layers of this fabric. Perhaps the variation in hight of the lock is the same, but it is better hidden in the thicker material. Thanks for the adwise on thread size. You can enlarge the photo to see more details. Would you think that the variation you see here got acceptable quality?
  5. The vinyl used here got a glass grid embeded between two PVC foils. It is 600 g/m2.
  6. I have tried to do some test sewing on two layers of vinyl with a Tex 135 polyester thread. I do have some variation in the balance. Some locks are near the top surface and some near the lower surface. I suspect, that you always will have some variation. I noticed, that sewing in the vinyl I got is quite critical regarding thread tension. An increase in thread tension of 10 % can change the seam from having the locks predominantly at the lower surface to be predominantly on the upper surface. But what can you expect from a good sewing machine? The picture below have red thread on the bobbin and black needle thread. Stitch length is about 4.3 mm. Would you think the thread tension is too low? Do the stitch got resonable quality? It is a close up photo, so details and errors should show up quite easily.
  7. If you trust Amazon, then it seems that Organ do deliver 135x17 titanium needles. But I am not sure this should be the right supplier to use. https://www.amazon.com/TITANIUM-135X17-Industrial-Sewing-Machine/dp/B01FGDJNJE?th=1
  8. I would keep away from a Chinese brand named "Flying Man". It do not mean, that all of their needles can't be used, but some are not useable. This is a close up photo from the same package of ball point needles from them. None of them were useable. One without a groove and the other almost no groove. I think needles from Organ, Groz-Beckert and Schmetz is considered good quality needles. I got a few needles from a brand called AMF, and they seems in order too. The Titanium needles is the same body of steel needle, but they got a kind of cheramic coating so they should last about 3 times longer with normal wear for normal woven fabrics. I am not sure about wear from leather.
  9. Even though this is an 2½ year old thread, I think it will be in order to revive it, because I know most people above giving information is still active in this forum. I have read the good references given above. I like to add, that in my impression that, nylon can be harder to color, and the amount of colors to buy are more limited with polyester thread. I guess, that the main advantage of nylon thread is, that it stretch more with the same tensile load. Nylon have got a lower youngs module than Polyester. If you get a concentrated tensile load on a seam, then nylon will be able to spread the load to more stitches than polyester. If you get one thread broken one place in a seam, the seam will slowly start to unravel from this position in the further use of the sewn product. Nylon do not seem to have a significantly higher tensile strength, than polyester got. I have noticed, that the thread brand, Amann recommends the use of nylon thread in high strength webbing applications for lifting purposes, that require high safety issues as well. However I discovered yesterday a video from Dr. Bob from Superior Threads. He mention, that nylon got a problem of being brittle over time, and got a low heat tolerance. I know, that the melting point of nylon and polyester got about the same melting temperature, but it do not mean, that a lower temperature may affect the thread. I know that Superior Threads do also sell nylon threads for leather. His audience in this video is garment home sewers - it may also be an issue here. But do Dr. Bob got a point here?
  10. I agree with Wiz. For the brushed DC motor type, the motor is controlled from zero. However the drive types with a brushed DC-motor do not have a steep moment curve as a brushless motor with more drive electronics. If you run a brushed DC motor drive for sewing machines very slow, and it gets some high torque load, the motor can be stopped. A brushless motor drive running slow will resist being stopped with all its torque available. In this way these servo motors are different and some may like one more than the other. And they may each be better for different jobs. This video show how this response to torque works on the two motor types: https://youtu.be/SOyQtt3eDLw The Jack servo motors are of the brushless type. I tried to look for their specification regarding lowest constant speed, but I could not find it.
  11. I just looked at motors from some suppliers in Europe, and I agree that it is hard to find the brushed DC motors. Almost all servo motors sold in Europe seems to be of the brushless type. I found one supplier in the UK via ebay with a brushed DC motor: https://www.ebay.co.uk/itm/Industrial-Sewing-Machine-Servo-Motor-Mains-240v-with-On-Off-switch-Fittings-/263472630087 I guess it will work like the Family motor Wizcrafts suggested. If you go for a brushless servo motor, as it seems most users do in Europe, then look for a motor with a minimum speed at 100 RPM. Most motors got a minimum speed at 200 RPM or even 500 RPM. Do not trust a specifications that say 0 RPM to 4500 RPM. It do have a minimum speed higher than zero. This is one brushless motor sold in Europe, with a minimum speed of 100 RPM: https://www.sewtex.de/Motore--Gestell--Tischplatte--Zubehoer-fuer-Naehmaschinen--Stuehle--Leuchten--Transportwagen--Industriestuhl--Schere/ZOJE-TZ-ZJ550W-S-Servomotor--Naehmaschinenmotor.html I guess you can find a supplier for that in UK as well. I never used a Zoje servo motor, but I have seen a few good reviews.
  12. I got no daubt that this is a good motor to use. But I am a bit puzzled by the specifications in the link: 110 volts AC, 550 Watts 3/4 HP output 3/4 HP output is the same as the same as 552 W shaft power. It is actually a bit more than the specificed input electrical power to the drive. I know something about this size of motors, and my estimate would be an effiency of about 60 % at max power output. So something is wrong with these figures. Perhaps the the specified shaft power is less or the specified input power is higher. If the motor provide 552 W shaft power at 60 % motor and drive efficiency, the input power should be 920 W.
  13. A facebook private group exsist with about 4000 members, and it is quite active. It is called China Leather Shoe Patcher. A lot of owners got problems with the machine in this group and others try to help. I think you need some mechanical handy man skills to be able to fix the problems with of it. Yes, it uses the normal needles for domestic sewing machines. But some do a modification to the needle bar on them, so they can use 135x17 needles.
  14. On this link from Groz-Beckert I find both 16x2 and 16x257 needles. The sizes are from 55/7 up to 110/18. https://my.groz-beckert.com/irj/portal/sewing#navurl://883c12ee6117b6739051dc523b91b68e?0
  15. This is a video, that in my opinion shows good speed control of a leather sewing machine and with an available servo motor. This is a video of speed control, with a DIY solution on a domestic sewing machine. I think it have got exceptional good speed control. It have got a very fast responsive foot pedal, and it have got a factor 70 between lowest speed and highest speed. If I was a manufacturer of a servo motor for leatherworkers, the performance should look like this:
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