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hackish

7-33 hook shape?

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I bought a Singer 7-33 and although it forms stitches it doesn't sew properly. Not to my standard. It was freshly "refurbished" when I bought it.

It stitches but will have a weird bunched up bottom side occasionally.

The concern I have is that maybe someone has modified this hook because there doesn't seem to be any relief at all for the needle to pass and I would have expected the tip of the hook to protrude at least as much as the depth of the needle scarf. I think it is perfectly flat as if someone put it on a surface grinder. It also chews the thread slightly.

A new hook is $300.





-Michael

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The needle is new and I've buffed any nicks on the hook. The tension is also correct. The needle height is correct and timing is not adjustable (it's correct anyway).

The bad stitches I show occur only about 1/50 stitches. The sewing machine mechanic said that's the best you'll get for a 60 year old machine but I know better.

When you look at the bad stitches it's almost like they're extra twisted. The thread 5 cord purchased from Paragear. I'm feeling like this is pointing to the hook. It is about 0.010" from touching on the downstroke and there is about 0.100" as the hook passes the scarf.

-Michael

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Try lowering both upper and lower thread tensions. Upper may be squeezing twist from thread. Make sure both threads are feeding smoothly. Try different densities of practice webbing. (condition U and condition R) Who knows? It may be one of these.

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back off the tension all the way on both the bobbin and top and increase until you get a good stitch... On my heavy duty machine, if its a hair too tight it will bunch up and catch every 30-90 stitches causing lots of headaches.. took a while to figure it out that it was overly twisting and or untwisting the thread allowing it to twist up and bind or the hook only catch half the thread and leave a nice half thread loop up top or underneath....

sounds similar...
I was that kid jumping out if his tree house with a bed sheet. My dad wouldn't let me use the ladder to try the roof...

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I'll play with the tension some more.

I removed the hook and ground the edges down. I also ground a relief in the back to provide more needle to hook clearance on the down-stroke. This has greatly reduced the fraying problem. The part I don't understand is why there is even a scarf on these needles because the hook would hit the needle on the down-stroke if it is closer than the edge of the needle.

-Michael

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It is the correct needle. Took a lot of orders to get the proper 7x1 #27. When I get time to work on it I will take pictures of what I'm talking about.

The hook the needle clearance is indeed adjustable, it's just that with an oscillating hook machine the hook needs clearance for the needle to pass on the way down before the hook tip passes the scarf and picks up the loop. The installed hook has no clearance at all so you could have the needle strike the hook every time so it springs back for the tip to pass in the scarf area. That doesn't seem right to me but it's how the machine came setup.

-Michael

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Don't try to set the hook so it passes within the scarf dip. Have the body of the hook in line with the shaft of the needle. The loop formed on the scarf side should be 1/16" or more. No need to have the hook closer than that. Worth a try. Remove top plate, run material, with bright flashlite, watch hook catching loop. You may have done this already. JT

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Hm. I suppose I'm sort of measuring a 2x4 with a micrometer here... I will try the flashlight thing but it's a bit frustrating because I never know when it will form a bad stitch so I haven't been able to catch it. I thought about sticking a gopro under there and then going back to see if I can see what is different on the bad ones.

-Michael

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It's not really possible to watch stitch formation. I found a hook assembly on ebay for $20 and it showed up today.

I didn't realize that the hook assembly in the machine is actually a knockoff. The genuine singer part is a lot thinner at the hook area. It doesn't have the same problem with pinching the thread. Swapped the hook and the problem seems to be gone! Yay. I have to stop buying sewing machines now.

-Michael

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hackish

I have to stop buying sewing machines now.



Maybe you should just stop buying ones that don't work properly! ;)

Glad you got the problem solved, hope the new hook wasn't too expensive.
"It's amazing what you can learn while you're not talking." - Skydivesg

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This machine was a good price and being sold by a repair shop as being freshly refurbished. I specified that it should be sewed off on 5 cord. Ultimately it came loaded with chisel tip leather needles and 6 cord. People don't care if there are some badly formed stitches on a buffing wheel but we rigger folk should be more picky for a reason.

I'm into it for about $150 for the hook, a couple bobbins, new takeup spring and the proper presser foot. A class 7 machine for $1500 is still good.

I just wish I could purchase a machine that's refurbished and sewn off and was ready to sew with. The good news is if I ever need a 3rd job as an industrial machine mechanic I'll be good to go!

-Michael

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hackish

This machine was a good price and being sold by a repair shop as being freshly refurbished.



Yeah, I saw that it was "freshly refurbished" in your earlier post. I was just having a bit of fun! :)

hackish

I'm into it for about $150 for the hook, a couple bobbins, new takeup spring and the proper presser foot. A class 7 machine for $1500 is still good.



Sounds pretty good to me!

hackish

I just wish I could purchase a machine that's refurbished and sewn off and was ready to sew with.



I've had the good fortune to have done that three times now. One was a craigslist find that worked perfectly, the other two were previously owned by someone whose name appears in Poynter's B|, they work perfectly too. I can't take credit for my good luck though...

Have fun with the class 7, and post some photos of what you do with it.
"It's amazing what you can learn while you're not talking." - Skydivesg

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You are a lucky one.

My machine collection started with a 112w140 sold to me by another rigger. I got completely screwed with a machine that was badly worn out and I over-paid, trusting that the price was fair. $800CAD and it needed an additional $400 in parts just to make it work.

Bought a 20U that sewed pretty well on the light thread it was used for but needed a lot of adjustments to get it to work properly with E-Thread.

Bought a Brother KE-430D. Had to replace a significant number of missing/worn out parts and it still doesn't sew perfectly. Turns out one of the stepper motor drivers was burned out on the main board so I had to buy a new component from China and repair it myself ($1000 for a new controller board... um... NO!). Machine was $3500 and I'm into it for about $600 in parts. I should have bought a brand new machine.

I'm really thinking of trading in my 112W140 for something else. Maybe newer and maybe with a puller. Whatever I get I'd be happy with something that just sews out of the box.

-Michael

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