Spin milled wedges

Why are they so good and how do they work?  I've just found out.

Well, I was going to leave it a bit for someone to spout the Vokey 'precision CNC milled grooves', but I can't be cruel.

It's obviously true that hitting the ball right will give the necessary spin, but I wondered how Titleist (and now MD) could claim such impressive spin rates when compared to conventional wedges.  Not only that, but people I've talked to have (only one of which I take with a pinch of salt) also say that it works wonders.

As some of you may have noticed I don't like marketing claims, I think they're bllcks (COR, enhanced MOI etc) to cynically manipulate a gullible public.  This one felt different, but I couldn't understand how precision milled grooves could effect spin rates.  The grooves on my wedge (a cheapo 60deg Maxfli) are about the same pitch, width and depth as an MD.  Assuming that I use a soft ball with about 3mm deflection and hit the ball dead square (some hope, I'm going to build a test rig to proove this)it gives a contact surface area on impact of about 376mm^2, but if the groove area is removed it leaves only 307mm^2 to 'grip' the ball.  It would seem, logically, that it must be the edges of the grooves that impart the spin, otherwise a completely flat face (no grooves) would be better because of the larger grip area.  I'm not convinced so I intend to fill the grooves up with body filler to try it.

And then I saw it.  They leave the machining marks on the face!  Semi-circular tooling marks where they scratch the area in between the grooves.  It grips the ball, thats all.

So, as soon as I build a test rig (to get repeatability) I'm going to try a completely grooveless face with a rough surface, a scratched, grooved face and one with various layers of sand paper on.  Any one care to bet which one will give the greatest spin?  If I can figure out a way of quantitavely measuring the spin that is....

Anyone still awake? 

Tim, let me know when you are set-up and I'll pop round with the video camera

Still waiting for the ball testing photos with you in your white overcoat  

I was going to use wet and dry paper but dumbed it down....

Now, how can I measure the spin speed?  What I really need is a green quality lawn, but mine's not up to it.  Maybe bouncing it off a rubber surface and measuring the bounce back, the higher the spin the shorter the bounce back....

Still working on that.

Any one know the rules about face finishes, grooves etc?

Who is it then David?

Nah, not really.  Need to see fig IX with regard to the surface finish, but interestingly the bigger grooves don't seem to be a requirement.  I'm currently working on a scratched face version

Yep, machining marks.  The 'CNC' bit is a bit of market speak.  I'm currently talking to a friend who may be able to CNC spark erode some dots on my old wedge, that should be interesting if I can fill the original grooves well enough. 

Quite tempted with the MD actually, heard some quite good things about them.  Part of the fun for me is inderstanding the mechanics behind the hype, nothing makes me giggle more than people falling hook, line and sinker for the lastest gizmo.  The spin milling, however, makes perfect sense.  Make even more sense if they got rid of the deep face grooves though...

As for my hand, it's OK.  The doctor said I may never play the piano again, but as I couldn't before I did it I'm not that fussed.

I would assume that either the machining marks have filled up with crud (mud and plastic from the ball), or more likely the edges have gone from the grooves.  Not much you can do unless you scrape out the edges again.  If you've got a precision scribe and a magnifying glass it's probably possible.  Going over to the local pro-shop to have a look at the MD's today. 

The big grooves aren't the problem, I use an old electric toothbrush and some soapy water to clean them out,  it's the machine marks on the face that are imparting the majority of the spin.  The toothbrush may clean the machining marks out if they haven't been blunted, but I suspect that hey wouldn't actually last long as most wedges are made from Maraging 610 stainless (soft).  Got to get the sharp edges back... 

Apologies, most of the wedges do appear to be are carbon steel, the soft stainless (maraging) heads are mainly used on the normal irons.  Thats why they are usually coated (such as the gunmetal, satin or cobalt - usually produced using vapour deposition) or 'oil can' (heated and dipped in oil).  The latter will go rusty, the stainless or coated ones wont.  Stainless will, however, stain and under certain circumstances it will 'rust', after being subject to elevated temperature.  This is due the interstacial bonding of the chromium and cobalt breaking down on the surface leading to the formation of small pure iron pockets.  And I didn't have to look that up David.

Top Tip  Try cleaning those stained and dull looking stainless steel parts of your golf clubs with baby oil, I prefer Johnsons (I get through a lot!).