Wednesday 24 April 2013

Overhaul: Wilson Hammer 5.8 + Syn Gut @ 32/28 lbs

While this racket has a similar composition of 80% Graphite and 20% Kevlar (link) as the PSC6.1, the feel is very different. 

Of course, since this was designed and built to be a player's stick but with "hammer-style" weight. Literally, it means very head-heavy. Stock balance point is 36cm (14.125").


I've tried multi/poly, full poly, full multi and multi/syn gut in this racket. In all these combinations, two things stand out. 


First, this is a very very stiff frame and off-centre hits punishes heavily with jarring vibrations. Just an hour with this is enough to give me wrist pain and elbow discomfort for a few days. (I estimate my sweetspot contact to be at about 60% with very good players and about 80% with casual hitters.)


Second, when the sweetspot is hit, it reminds me very much of my PSC6.1. I believe there is potential in this racket.


Since I don't think I can up my sweetspot contact percentage, the next best thing, is to deal with the unhealthy vibrations through modifications or tweaks. 


I acquired a frequency meter and was having fun measuring string tension, racket frequency and vibration frequency with it.


Since the main gripe about this racket is the shock, I searched and studied many articles about racket frame frequencies (link) and vibrations (link). 


I decided to experiment with this stick.


At below 300g strung and gripped, the stock frame has plenty of room for customisations. Only the balance is way off.


Before any work started, I recorded all the frequencies I could.




Then I strung the racket so that I could feel the bounce of a ball off the strings rather than just relying on the frequency. I bounced a golf ball instead as the hard outer covering generated more distinct vibrations than the soft felt of the tennis ball.


The last setup was 32/30 lbs (link) and that it felt much tighter than my 16x18 PSC6.1. So I dropped two more pounds on the crosses to make it 32/28 lbs this time.






After stringing, the leather grip is removed. All the lead tape I previously applied on the grip pallet are showing up. It should be around 18g.




The butt cap was taken off and I recall previously stuffing 15g of lead inside the cap. This racket came with the "In-Tune Handle System" and had a piece of rubber protruding from the butt cap. It weighs 14g on its own.




Here comes the most crucial part in this mod. Many rackets are pre-filled with foam in the factory. The objective is to reduce vibrations and add stability.


The pic below shows the stock foam that was filled at the factory.




To change the racket vibration frequencies is to change the overall density. I dug out as much of the foam as I could. Given the years, a lot of the old foam has become dry and brittle. So dry, it feels crispy to the touch.




When the foam is squeezed, it does not bounce back much. I suspect the foam has exceeded its useful life. Here's another look at some of the foam.


Below pic shows the hollow butt with the foam removed.




At every stage, details like the weight, balance and frequencies are recorded to ensure I do not go too far off-track from my plans. The racket is so head-heavy at this point that I had to stand it on its butt to measure weight.



I tried filling the frame with many different types of materials, one at a time, and then tapping the frame and strings and recording the frequencies. 

This is a very tedious and tiring process. The materials must be packed tight, which made it difficult to extricate. But there is no other way I can think of as every racket and material exhibit different frequencies and vibration tendencies.


Some materials made the stringbed feel too dead. Others accentuated the vibrations! Studying the data I collected, and by the process of elimination, I soon arrived at a very narrow frequency range which seems to work well with the frame and the ELT stringbed.


Obviously, I did not have enough hands (...and patience) to take pics of all the different materials I tried. Below pic shows the insertion of polystyrene beads. I bought a few different packs with different densities and tried them all.



Below pic shows the insertion of a mid-density gel-like moulding resin.



After obtaining what I thought was the best possible outcome, I nailed the buttcap back on.




The weight and balance is further fine-tuned before I re-installed the leather grip.

So far, the few simple bounce tests seems promising. The frequency changed and vibrations are also A LOT LESS than when I started. 


Only the acid test remains!

Playtest:

- This modification is a SUCCESS!!!
- Almost ALL of the jarring vibrations have been removed. I deliberately hit the ball around the entire racket frame and the very edges of the stringbed all around. I can feel the mishits. But the previous stinging painful evil vibes are gone!!! In its place is just a low, soft and very short-duration "thud". That's it!
- The sweetspot increased tremendously! Stability improved. I kept total weight and balance very similar to how the frame was before the overhaul. So it cannot be due to weight or balance changes.
- Ball contacts on sweetspot got sweeter. The feel is so pure now that I think it's even nicer than my PSC6.1!
- My confidence with this frame has soared.
- I played almost an entire continuous hour with this, intentionally clobbering every shot at full strength. Exhausted? Yes! Discomfort? Zilch!
- The 7+ hours I spent was totally worth it! Just don't ask me to do it again...

- Ball fur pic below






Rackets, rackets on the floor,
Who's the sweetest of them all?
"It's me, it's me" says the Hammer,
"Oh yes, oh yes, I agree!"


27Apr2013 update:
- I'm still reeling in shock at how well the Hammer 5.8 played after modifications. 
- To confirm my findings, I brought out my best feeling rackets and invited someone with very sensitive hands to try the Hammer. (It's a blind test)
- The Hammer won, hands down. There is just no competition. Neither my PSC6.1 with natural gut, ProStaff 6.0 85 nor the RD7 could match the comfort and feel.
- The absence of "noise" and unwanted vibrations allowed us to feel ONLY what we needed and was supposed to be felt during ball impact.
- Despite the impressive dampening, it does not feel dead, muffled nor suppressed at all. It's actually very lively! 
- The difference is somewhat similar to listening to a symphony orchestra in a park and in a grand concert hall where there is no noise and near perfect acoustics.
- The pocketing is unmistakable. What is different here is I could even tell when the stringbed was depressing and when the stringbed was rebounding.
- Sweetspot hits are extremely clean, quiet and stable. It is not something I have felt in a tennis racket before.
- With such great feedback, learning and adaptability to this stick becomes unusually fast. Simply because it is focused and there is no peripheral noise.
- As usual, my partner wanted this racket. But I'm putting my foot down this time. Definitely not!






Strings:
Pro Supex Synthetic Gut Titan 1.25mm @ 32/28 lbs (varied crosses)



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