Popplock T4

Update 23 October 2017 - Dear Reader, please check out my new puzzle blog and e-store at http://mechanical-puzzles.com

The word is out that Rainer Popp's T7 puzzle lock will be available sometime very soon. Hence for the last week or so, I have been labouring over the T4, hoping to solve it and round off my reviews for the Popplock series before the T7 makes it first appearance. The T4 is really one serious tough cookie of a puzzle lock...but more onto that later.

Clockwise from left: T3, T2, T5, T4 and T6

The T4 is Rainer's 4th puzzle lock in his famous Popplock series. I obtained this lock last year courtesy of Wil Strijbos who happened to have one last piece left. As far as I can tell, the T4s are all in private hands and not commercially available anywhere. For reviews of the rest of the Popplock range (except the T1), you can check out my earlier posts for the T2, T3, T5, and T6, all pictured above.

T4 with Rainer Popp's Signature Cat Face Logo

Physically the T4 is a large and very heavy lock, maybe not as large as the T5, the latter which is humongous but certainly its body is much thicker than the T2, T3 and T6 at nearly 5cm in depth. Overall height and width is about 8.7cm by 6cm. The body is uniformly round and symmetrically shaped on both sides front and back. The lock is milled from a single solid block of brass and the shackle is stainless steel. As with all of Rainer's locks, the quality of construction, fit and finish is really excellent and all moving parts are manufactured to incredible tolerances. In front of the lock is Rainer's signature "cat face" logo. The T4 comes with a steel key but on first inspection there appears no key hole anywhere to be found for a key to be inserted....strange!

There are 5 steps to opening the T4 according to Rainer. Well, depending on how you count each step, Steps 1 and 2 are relatively easy and pretty obvious. I managed them in several seconds. However the next couple of steps stumped me...and I made no progress whatsoever for quite some time. No amount of shaking, tapping, tugging etc helped. My fingers were numb and hands tired. I had very much expected the T4 to be difficult and especially Step 3 to be the major obstacle after having read the experiences of puzzle bloggers Oli, Brian, Jeff and Jonas with the T4; but I did not imagine it would be that difficult!  It came to a point where I decided that I really needed a hint to move forward as I was getting nowhere after Steps 1 and 2.

Oli came to my rescue and after an exchange of emails over several days, I managed to overcome Step 3. Step 3 is so well disguised that I would not have been able to solve it on my own. A big thanks to Oli for giving me only one tiny hint at a time so as not to spoil my fun (or frustration) in solving the T4. Step 4 was easy, no sweat. But then it was Step 5 that got me stuck in my tracks again. Again, very tricky! Thankfully this time round, through some trial and error, I achieved Step 5 much more quickly and with that, I finally pulled the shackle out of the lock...whew!!

As I mentioned in my earlier posts on the Popplock series, the T4 is generally considered the hardest in the range from T2-T6. I am really glad I left it to the last, otherwise it would be been pretty discouraging for me if I had started with the T4 before the rest. I personally think that the T4 is so much harder than the next most difficult lock in line, the T6. On hindsight, the T5, which came out after the T4, seems comparatively easy. It was the T6 which brought the difficulty quotient back up a couple of notches. 

Now the wait for me and other puzzle lock lovers is the T7. From what I gather, the T7 will really be huge; I don't mean the physical size...as I have not even seen it yet, but it would be huge in terms of challenge (and in all likelihood, the price as well!). Stay tuned!