1 Topic by salsaman

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Topic: Filament drive gear set screw trouble

I wonder if anybody can offer clues to loosening the set screw on the filament drive gear.

The set screw on mine has dried black stuff (glue?) around the threads, and while a 1/16" hex head fits, it slips instead of loosening the screw.  My suspicion is that it was tightened until the head stripped at the factory, then it was glued; after replacing so many parts up to this point, I've come to expect poor quality construction from the SD factory.

I fear the worst, so a good source for a replacement drive gear and motor would be great too!

fwiw I need to slide the gear a bit outwards for this extruder:
er, link not allowed (???), but it's thing:271506

SD3 mid-2013 with Lawsy Mk5 extruder and carriages, E3D hot end, 30A power supply w/enif cover

2 Reply by accusedmonk

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Re: Filament drive gear set screw trouble

One problem you're having is the screws are metric.  I didn't have trouble adjusting mine for my e3d, although it was tight enough to make a small burr on the shaft.

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3 Reply by salsaman

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Re: Filament drive gear set screw trouble

That's what I thought, and tried a 1.5mm hex key first, which turned in the screw head with little resistance.  Then I tried 1/16", which is ~1.59mm, which seemed to fit tightly, but it wouldn't break the lock and turned in the screw head.

Do you know what size it is?  My metric hex key sets go from 1.5mm to 2mm, and the 2mm head won't fit at all.

Are the shafts not flatted for the set screw?

SD3 mid-2013 with Lawsy Mk5 extruder and carriages, E3D hot end, 30A power supply w/enif cover

4 Reply by ronsii

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Re: Filament drive gear set screw trouble

SD uses some loctite/superglue as a thread locker so you may have to 'work' the proper key into it.

Correct: no flats on the motor... if you have the means it is a good mod to do though smile

5 Reply by grob

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Re: Filament drive gear set screw trouble

1/16" ~= 1.59mm. Those M3 set screws have a 1.50mm hex. It should have been tight rather than loose - definitely something wrong there.

Note it's normal (in fact good) to apply thread lock to threads like this, but if the set screw socket is stripped then that's a bit of a problem. Are you able to upload an image of the problem screw, particularly including the evidence of glue? If it is loctite on the thread (or something similar) then applying heat to the screw with a soldering iron can sometimes help break it down to aid loosening.

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6 Reply by wardjr

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Re: Filament drive gear set screw trouble

grob wrote:

1/16" ~= 1.59mm. Those M3 set screws have a 1.50mm hex. It should have been tight rather than loose - definitely something wrong there.

Note it's normal (in fact good) to apply thread lock to threads like this, but if the set screw socket is stripped then that's a bit of a problem. Are you able to upload an image of the problem screw, particularly including the evidence of glue? If it is loctite on the thread (or something similar) then applying heat to the screw with a soldering iron can sometimes help break it down to aid loosening.

+1 for heat even a lighter will loosen up the lock tight.  Also putting some side angle force on the wrench can help take up some play.

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7 Reply by ronsii

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Re: Filament drive gear set screw trouble

Another trick is to use some 'grit' on the allen key... like toothpaste, diamond  grit, basically anything abrasive that is fine enough to 'dip' a layer onto the key as it will give added traction to the metal on metal connection of the key and grub screw.

8 Reply by salsaman

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Re: Filament drive gear set screw trouble

Thanks folks, good advice, but the more things I try, the more clear it is that this hex head was stripped when I got it.  Again, this does not surprise me.

So I'm drilling out the screw.  I've got 1.1mm to go, but of course killed a few bits in the process, so more tomorrow.  I haven't messed up the threads too badly, but I might as well replace the gear: looks like a MK7, should be able to get one for $10 or so.

SD3 mid-2013 with Lawsy Mk5 extruder and carriages, E3D hot end, 30A power supply w/enif cover

9 Reply by ronsii

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Re: Filament drive gear set screw trouble

If you can pick up a left hand drill bit it will help as they can unscrew what's left of the screw when drilling, also there are some torx sizes that mesh very well with certain sizes of hex that are stripped... sometimes they can save the day.

10 Reply by salsaman

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Re: Filament drive gear set screw trouble

Oh crap I meant to try torx... too late!  T7 might have worked, I'll never know.

I have a new gear on the way, also more 2.5mm bits smile  I'll put the Mk5 extruder back tomorrow.

Thanks again, glad to be participating in the forums.

SD3 mid-2013 with Lawsy Mk5 extruder and carriages, E3D hot end, 30A power supply w/enif cover