7-33

[thomas555]

my 7-33 sewing machine the fulcrum wheel has a pin and two stub screws one of them losen and when it dose the wheel loosens from the shaft, i have added thread lock just new i think the machine maybe ruined.

[jimi]

Could you send a picture or two?

[thomas555]

22 minutes ago, jimi said:

Could you send a picture or two?

hope you can see the part in that hole is a grub screw it tends to loosen by times when it dose the block wheel loses grip from the drive shaft, I have added lock tight to the screw but it might work it could be the pin that's also the problem, this thread lock when used will cause the thread to lock for ever.

[nylonRigging]

Are you sure it the exact same pitch TPI bolt as it should be ? , being it is so loose now ? 
Or is the threads just so worn in screw and hole both, that maybe it so loose ?

( it does happen ) . If someone has over torqued and eaten-up/stripped some of the thread that were tapped in the hole .
You can dissemble the part . then drill/ bore over-size a tiny bit , then just Thread-tap the hole to a tiny big larger Grub Screw ?

Easy job to drill and tap new screw . the longest part of the job is disassembly and re-assemble again .
.

[jimi]

well if that´s stuck forever then not much to do? Sometimes they do slacken off, If it has a pin through it then at least i will not fall off. You will have to tighten up the grub screws the best you can. Have a look to see if your large flywheel is not loose also. This could pull on your cam if loose.

[thomas555]

thank you all will look further into this,