Help! I can’t get this screw out of my SP-15!

Here’s the end on view. Doesn’t the set screw hole appear to be in the wrong spot?

Hi All!
This screw in the vibrator assembly of my SP-15, a screw which my manual tells me is properly know as the Crescent Holder, is stuck. It has been three days now soaking in alternating baths of WD-40 and PB Blaster, and it still won’t budge.

It’s purpose is to insert the Crescent into the Worm, so that we get the oscillation (or vibration) we need to spread ink. The worm itself will turn about one-half turn with relative ease. I’m a bit afraid to force it after that.

I am open to suggestions about how to persuade this screw to exit — preferably leaving it intact. I have not, as yet, involved any process that includes the use of a propane torch, but wonder if that would be a viable option.

Thanks for any help.


23 thoughts on “Help! I can’t get this screw out of my SP-15!

  1. firebrandpress - September 24, 2012

    I’m late to the party, but I found a cleaner called Krud Kutter at my local hardware store (non-toxic, not abrasive) that works shockingly well for cleaning parts. It took about 20 years worth of grime off our #3 and freed quite a few parts that were lodged in place with dirt and ink.

  2. Enrique - September 19, 2012

    It’s awesome you found the worm collar.
    And that’s a wise advice from your machinist.
    Better exhaust your possibilities before trying anything on the lathe.
    In the end, cosmetically it might not look so great, but functionally it should work perfectly fine, unless there are deep scratches beneath the rust.
    Keep us posted. At least I’m very interested in seeing your progress.
    Good luck!

  3. GregHankins - September 19, 2012

    Update — Thought Fritz was willing to have a worm collar made for me, I actually found the original, rummaging through and as-yet-unopened box of miscellaneous stuff. So we now have an operational vibrator — though it is still undergoing EvapoRust treatments. For what it’s worth, my machinist counseled polishing with Scothbrite pads rather than machining. Depending on the success of the EvapoRust, I may have him put it on a lathe for the polishing.

  4. GregHankins - September 17, 2012

    I’m not sure what the spec for the Crescent Holder Set Screw on a 219 is, but my copy of Sheet No. 254 for the SP15 specs it like this: .250-20 H.H. Set Screw. it is a pretty darned short little devil.

  5. GregHankins - September 17, 2012

    MYSTERY SOLVED! I journeyed down to my local machine shop today, where the proprietor used an impact driver to extract the mystery screw, It turned out to be . . . . the Crescent Holder. And below it was an intact crescent. Both seem undamaged, and the crescent walks down the worm and reverses, just as it was designed to do. What’s missing, however, is the Worm Collar and its set screw, which I hope to order from Fritz. I really appreciate all the advice and help.

  6. Widmark - September 17, 2012

    I take it back, it’s off axis on my 219 as well!

    Before I take it out and measure it, Fritz (or anyone), any idea what the specs for the set screw should be? My crescent holder keeps working itself tight. When Dave Seat was here he took it out and cleaned it out and we assumed some old ink was keeping the set screw from holding the crescent holder tight and it worked well for a while but then it started doing it again, where I’ll hear the oscillator jump and can see that it’s suddenly tight and I have to back off on the holder again. I’m wondering if my set screw isn’t just worn down?

  7. Eric Holub - September 16, 2012

    The setscrew in this configuration will contact the threads of the holder almost at a tangent, but with enough contact to do the job. And maybe with less chance of thread damage, compared to a setscrew that locks right on the axis.

  8. Fritz Klinke - September 15, 2012

    Now that it’s daylight, I think there is no crescent present or some sort of substitute and we are seeing the threads for the crescent holder. When that hole is drilled through the tube and into the end casting, it is then threaded all the way. And the retaining set screw is absolutely in the correct position for the SP-15.

  9. Widmark - September 15, 2012

    Regarding the question in the photo caption…is it normal for the set screw to be so far from the crescent holder? On my 219 it’s directly in line. In this photo it’s hard to see how the set screw would secure the crescent holder.

  10. Eric Holub - September 15, 2012

    OK, I misremebered the position of the setscrew (it seems Alzheimer’s may be contagious). Fritz is right about the visible threds, it suggests that the crescent isn’t there, or maybe it broke off and only its post is left.
    Another thing, if the setscrew has been over-tightened to the point it damages the threads of the holder, it may also interfere with removal, as will dried ink or thread-lock compound.

  11. GregHankins - September 15, 2012

    Fritz – Thanks for your thoughts on using a torch — and for the info on the screw not resembling a crescent. If this is not the crescent, then I have fewer worries about trying to preserve it while extracting it. Looks like I might be ordering a crescent and crescent holder!

  12. Fritz Klinke - September 15, 2012

    What’s wrong with the end view of the ink drum?? It sure looks like someone replaced the crescent with a threaded screw–there are no threads on a crescent and I see a lot of threads staring back at me, and that’s why the thing doesn’t work in the first place. This thing is literally screwed up.


  13. Fritz Klinke - September 15, 2012

    An impact screw driver may work, but I’d try the propane torch approach first, heating the head of the screw and the area around it to cause expansion of the drum and crescent holder–that often breaks things loose. It may be a combination of rust and ink that is holding the holder in place and heat will cause the ink to loosen up.

    The set screw is indeed in the right place and has to be backed off as the very first thing. We have replacement crescent holders and crescents, so it’s not a loss if the head of the holder breaks or has to be drilled out, but the crescent stem goes up inside the holder and the crescent is hardened cast steel.

    The cresent stem needs periodic lubrication with graphite grease as a point of reference. And has been pointed out, get rid of all that rust on the ink drum.


  14. GregHankins - September 14, 2012

    Thanks much for the canned air suggestion. I’ve never heard of that technique; it’s brilliant!

  15. Ray Nichols - September 14, 2012

    You might try buying a can of spray air and just blasting it for a bit to radically cool the metal. Might get the seal between them to break enough to get the screw moving. I’ve done this a couple of times on other kinds of things like this.

  16. GregHankins - September 14, 2012

    Thanks, Paul. Good to know that is in fact where the set screw should be. But I’m confused as to how a set screw in that location can affect the Crescent Holder Screw, which it does seem to even touch. Or does it just kiss the side of the Crescent Holder? I will give your Vise Grip strategy a try. So far, the problem has been that the screw just won’t budge, so the screwdriver wants to slip out of the track, with the usual threat of damage to the screw slot.

  17. Paul Moxon, Moderator - September 13, 2012

    The set screw is the the normal postion. Once it is backed out, lock a pair of Vise Grippers onto the shaft of your screw driver and turn it counterclockwise.

  18. GregHankins - September 13, 2012

    I do now have a puddle of EvapoRust on top of the screw, attempting to give Enrique’s suggestion a whirl. And I may well take the whole kit down to the machine shop in the morning.

  19. GregHankins - September 13, 2012

    I do not seem to be able to add a photo to a comment, so I have added a photo above for one that shows the end of my vibrator. Note that the set screw is not in line with the Crescent Holder screw. Is this odd? I have removed the set screw with no trouble. It appears to be completely undamaged in any way.

  20. Enrique - September 13, 2012

    My recommendation would be to remove all the rust first with evapo-Rust. A nice and generous bath for a day or so.. and then try to get it out.. you definitely have rust in your screw.

  21. Eric Holub - September 13, 2012

    Yes, the allen set screw would be the problem, especially when you don’t know it is there.
    The strange thing is it is not visible in the picture. I can see the notch that the crescent slides though, and the set screw should be in line between the notch and the holder screw in question. I don’t see a thing. Can it be buried under a perfect layer of silver ink?

  22. Ladboyle - September 13, 2012

    Think about letting a machine shop get the screw out for you. If you mess it up, it will cost a lot more to deal with the new problem

  23. Widmark - September 13, 2012

    Have you applied the PB Blaster to the set screw on the side as well? Though I imagine it should soak through from the top. I have a similar issue in which my crescent holder works itself tight during use, despite the set screw being tight, so I routinely (not too often), have to pull back on the holder. I probably need a new set screw.

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