GroverAccordion Accessory (502C)

This is a good tuner, but just a little misleading that they describe it as "using the rotomatic design", and a "perfect replacement". It is not those things, although it is close and it will fit in the same hole as an original rotomatic.The physical dimensions are different than the original design both in the footprint, the stem length, and the stem housing length that extends into the headstock to support the tuner. For exact physical specificiations see the manufacturer's website for the drawings on this and other grover tuners. If you compare these "rotogrips" to "rotomatics" you will see many dimensions are different and the rotogrips are slightly smaller. I was going to post the drawings here but I don't see a way to post a photo, just videos.PROS- Quality product- 18 to 1 tuning ratio vs. 14:1 on original rotomatic- Available in Chrome, Gold or "black chrome"- Fits into same headstock hole as original rotomatics, and screw on back is and exact fit to the placement of that screw on original rotomatics.- Locking mechanism for fast string changes, also great for bigsby guitars.CONS- Not available in Nickel Finish - which means many Gibson guitars hardware won't match.- Stem is shorter than orginal rotomatics. Might be ok, but on my 335 it looked like it was going to be kind of annoying to try to get the string into the tuner. They needed to be a little longer.- Back casing is different dimensions than original rotomatics, and is SMALLER so may reveal small marks on the back of the headstock from original tuners.TUTORIAL ON GROVERSThe 102 is the orginal rotomatic. It is offered in Chrome, Nickel, Gold, and Black Chrome. It has a 14:1 turn ratio.The 102-18 is the same dimensions as the 102, but has a 18:1 turn ratio. It is also offered in the same 4 finishes - Gold, Chrome, Black Chrome and Nickel.The 502C is this Chrome, locking "roto-grip." It is similar to, but a little different from the original rotomatics in that it has a locking mechanism, and has somewhat different dimensions. It is offered in Chrome (502C), Gold (502G), and Black Chrome (502BC) but not Nickel.(update): The 106 series is also a locking tuner, but doesn't have the knob on the back. It is available in Chrome (106C), Black Chrome (106BC), and Gold (106G). It locks using an internal cam rather than a manual thumbwheel on the back. Gover describes it like this: "Simply insert the string through the string hole, pull to tension by hand and begin tuning. As you start to tune, only the locking cam in the string post turns. Once the string is locked, the string post begins to turn allowing you to bring the string to pitch. In less then one revolution of the string post, you will be in tune, to stay in tune. Gear ratio is 18:1." I just ordered a set of these and will try them out on a guitar that has standard rotomatics in Gold hardware. Unfortunately, if I like the 106, it is also not offered in Nickel and so won't match my ES-335 that has standard rotomatics in nickel. Shame really.I contacted the company about the nickel finish and they said they "offered them 5 years ago but the product bombed because the purists who had nickel hardware didn't like locking tuners". Personally, I think they just didn't leave them in market long enough to align with many of the newer Gibsons with Nickel that people may wait a few years then decide to "upgrade". The 502 will fit in the same size headstock hole as the 102's but will not extend as deep into the headstock with the casing. The stem is somewhat shorter than the orginals which could be problematic depending on the thickness of the headstock on your particular guitar. The small screw on the back is positioned exactly the same as on a 102. In that sense it is a "drop in" match, but not an exact match. There are also two very small "dots" on the back surface designed to dig into the back of the headstock and help keep the tuner from twisting in the slot (in addition to the screw). The 102 does not have these so when you insert the 502 in the hole you actually have to get it well positioned and put the small screw in part way, then screw in the barrel nut from the front face and tighten it down making sure you have the tuner exactly where you want it. These are barely noticeable unless you look closely, but they are a difference between thh 102 and the 502. At first I thought the housing was bent because it didn't sit flush. Then I inspected the back face with a magnifying glass and my thumbnail and discovered the tiny "dots". Again - not a big deal, just describing them here for readers who may be considering dropping these in as a replacement for original grovers.There is a small risk of revealing markings around the outside back of the tuners since the dimensions are slightly smaller on the rotogrips, but the differences are pretty small and only the perfectionists will notice that difference. The stem length could be a bigger issue depending on the thickness of your headstock.SUMMARYGood product, looks and feels like a Grover and has a locking mechanism. Be sure you don't have nickel hardware if you are ordering these or it won't match. "Works" as a replacement for an original rotomatic, but not an exact match replacement and might have some annoyances with the fit depending on your specific guitar. If you're just not sure, try them and if you're not satisfied with the fit, send 'em back like I did. Might cost you a few bucks in shipping.

They are not direct replacement for Epiphone Les Paul Ultra 3. 592C is smaller than the stock tuner.

Great tuner! Works well!

Perfect in every way! They are a drop-in replacement with a perfect fit.You will need to drill pilot holes for the securing screws on the back - that shouldn't be a surprise.The look, the fit, and the feel are absolutely outstanding. These are fantastic and very high quality.Some tips for installing...After removing the robotic tuners and cleaning everything up, I was trying to think of the best way to make sure these were perfectly aligned, and I think I did pretty well. Here's what I did...Securely place the guitar face down on your clean/protected work surface or hang it backward on a suitable stand.Install them two-at-a-time, from the bottom set to the top. This makes it easier to align using my method.Pop in the bottom two.Put the washer on the front - be sure the beveled side faces out.Install the nuts and get them barely snug.Line them up by eye and snug them up a bit more. They should still be able to be moved - not move on their own, and not very tight at all.Next, I used a STRAIGHT wood block (about 1" x 1" and 4" long) and laid it across the tops of both tuners at the same time.Line them up again so that the tops of the tuners are flush with the wood block with BOTH at the same time.Snug them up pretty good now - not to final tightness, but fairly snug.Now if you check with the wood block, they probably slipped just a bit when snugging them up, so make final alignment adjustments.Both tuners should be perfectly flat against the block at the same time and pretty snugly tightened.Using an awl (or ice pick or similar), very carefully make a small dimple where you'll drill - CENTER it carefully and make a good dimple.That will guide the drill bit.Using a 1/16" drill bit and masking tape to mark the depth, insert one of the screws into the tuner so you see how much of the screw goes into the wood.Wrap a small piece of masking tape where you want to stop drilling. I usually leave just about 1-2 threads' worth un-drilled so the screw bites into the wood at the end.Do NOT NOT drill! I've seen folks just drive the screws without pilot holes and that's just not a good idea, especially if you're putting 3 screws in a straight line into hardwood.Mark carefully. Set depth carefully. Drill carefully.Drive in the screws. It's not a strength competition. Just get them screwed in and snug.Go back and make final tightening on the nuts on the front.Same thing for the next two sets.Enjoy!

Replaced it at a local Luthier due to being a chicken, but there is no drilling involved.Upgraded my Les Paul studio very nicely.