Needle size

We are building a boat bimini (a fabric shelter that shades the cockpit) out of 8 oz. Sunbrella fabric. The thing is about ten feet by ten feet and is made up of several panels with full width zippers at each end. We are using a Yamata staright-stitch industrial machine, which has taken us a very, very long time to get set up properly. So many dials to twiddle! We are using DB 92 bonded polyester thread and Innnova DBx1 #18 needles. It seems to be working. Our greatest problem, actually, is controlling the speed of the machine. It takes an extremely light touch on the treadle indeed. One slip and it runs away, breaking and snarling threads and sometimes needles too. That is one humongous motor!
Is there a better thread/needle combination? Various trouble-shooting guides we have seen say "Use proper thread or needle" or "Replace needle with correct size" or "Choose correct size needle for thread and fabric." No argument here. But how does one determine what the correct sizes are?
Reply to
Gogarty
What is the model of the machine? Not all industrial machines are capable of handling that thread.
To slow the maximum speed you can put a smaller pulley on the motor but learning to feather the treadle is your best bet. An experienced operator can make a machine like that sew at painfully slow speeds
Reply to
Ron Anderson
Is the thread coming off the side of the cone, or off the top? It is supposed to come off the top. If it doesn't, it doesn't stay twisted tight.
Also, I have found el cheapo thread frays easily. Once, after a needle break, I had a sharp edge at the top of the bobbin cage which I filed smooth with emory paper. I understand very high speed machines like to have silicone oil applied to the thread before it gets to the needle.
If that machine has a brush type motor (probably not, Ron can tell you) you can put an in-line "speed controler" (available from Grainger and other places) in the power cord. A speed controler can give you full power at most any low motor speed you want to dial in.
Reply to
jaxashby
Where have I run across snipped-for-privacy@aol.com before?
The machine is a Yamata GC8500 with a half horsepower clutch motor. We are getting very good at feathering the treadle.
From all I have read so far it would appear that the #18 universal needle and the 92 polyester thread are correct when all the other variables are set correctly, which is pure trial and error. This machine will sew though eight layers of 8 oz cloth like a hot knife through butter. But the settings are supercritical, especially the needle to bobbin timing. I think we have it now. Practice, practice, practice.
Reply to
Gogarty
Size 92 is borderline to heavy for that machine. With a lot of coaxing you might get it to sew right but that is not the machine for that type work. A walking foot machine is preferable.
Reply to
Ron Anderson

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