Hi Cecilia - chiming in to agree in one sense with what's already been suggested, but I work with industrials in mainstream fashion production as well as owning a few vintage machine. There is a huge difference in the power of the machines, just due to the motor. An industrial straight sewer need not be an expensive investment (forgive me if this is what a Sailrite is, I haven't heard of those) but I think an old Singer industrial would be perfect for your friend if you can find one in good condition.
The small piece of extra info I wanted to add is that through chats with my LSMG, he tells me he actually sets the machine up to handle whatever his customers are sewing, eg. leather or canvas. I know it sometimes involves re-setting the needle bar and adding roller foot or whatever would be required for optimal feeding. If they are sewing the same thing over and over, like your friend, it could be worth getting not only a sturdy machine, but one that is set up for the job. Mike has a great Singer industrial that would be perfect for this
http://www.quiltingboard.com/vintage...ml#post6495730- or I agree that a Pfaff 130, maybe an older Necchi BU or Esperia, and older Phoenix, Pfaff 238 Industrial, maybe a Singer 201 or 15 (but I doubt they need the stitching to be that pretty
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