Gear stuck on end of THK KR2001 A, how do I remove it?

[Roundel]

Hi everyone, I got a THK rail to use with MJKZZ's kit. It has a gear that used to attach to a pulley on the end of it that won't come off. I figured all I needed to do was remove the set screw and pull it off but that didn't work. Is there some trick I am missing?

Photos are crap but get the idea across.

[genera]

Have you rotated the pulley to check for additional setscrews?

[mjkzz]

maybe heat the pulley a bit so that it will expand.

[elf]

My guess is the set screw galled the shaft. A bearing (or wheel) puller may be needed to remove the pulley.

[Chris S.]

I also would try heat. Is that bit of blue evidence that a thread-locker was used? If so, the presence of this substance could be the culprit. Although the blue-type thread-locker that I've used can normally be removed with hand tools, there can be exceptions:

From the technical datasheet for Locktite Threadlocker Blue 242®: "For disassembly, shear with standard hand tools and remove with methylene chloride. In rare instances where hand tools do not work because
of excessive engagement length, apply localized heat to nut or bolt to approximately 482°F (250°C). Disassemble while hot."

In case you don't already have something to heat this part with, I use a "W.E.P 858D." This hot air station costs $60, has digital temperature control, and an output attachment that provides a pencil-thick stream of heated air. (There are other 585 units on Amazon that look similar and cost less. I can't say how well they work, though. My unit lives above my electronics bench, and gets constant use.

--Chris S.

[Roundel]

I managed to get it! I decided to be bold and risk a little damage by holding the far end of the screw with needle nosed vice grips and twisting the hell out of the gear until it came off. Everything still spins smoothly and any damage to the threads on the screw are far from where they'll engage with any other mechanism. I had tried heating before I posted here and it didn't go so well. Thanks for the suggestions! I think it had locktite on it, good guess.

[Smokedaddy]

... soldering iron works too.

[mawyatt]

Glad you could get it off, hopefully without any damage.

Use the THK KR20 also, great focus rail with Peter's MJKZZ kit.

I found for mounting the KR20 to my setup a ARCA plate works well and allows easy removal. Just get an inexpensive long (150mm) ARCA plate and drill and tap 4 holes in the plate for the KR20 bottom recessed holes to allow a M3 Allen head bolt to securely attach the KR20 to the plate.

Best,