Understanding ball roll: Wood v Slate

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PickeringRC

Registered
Hi guys, just trying to figure something out that seems to make no sense to me!

It seems common knowledge that on a wood MDF bed table, the balls will roll significantly slower than on a slate bed table, even if using the same cloth, right?!

I am no scientist, but I can't get my head round this?!

If you roll a ball directly over both surfaces, I can understand one will go further due to the different ball to surface drag coefficients.

Put a cloth in between though and the drag coefficient is the same regardless of what is underneath, and sure, MDF may not be as dense or solid as slate, but I can't see it "deforming" with the weight of a ball sufficient to increase the drag coefficient to anything other than just that of the cloth.

So why are MDF tables slower?!

PS, only interested in speed here, I know that for a level play area slate will always be better along with a whole host of other benefits it brings to the table.
 
bradsh98

bradsh98

Bradshaw Billiard Service
Silver Member
PickeringRC said:
Hi guys, just trying to figure something out that seems to make no sense to me!

It seems common knowledge that on a wood MDF bed table, the balls will roll significantly slower than on a slate bed table, even if using the same cloth, right?!

I am no scientist, but I can't get my head round this?!

If you roll a ball directly over both surfaces, I can understand one will go further due to the different ball to surface drag coefficients.

Put a cloth in between though and the drag coefficient is the same regardless of what is underneath, and sure, MDF may not be as dense or solid as slate, but I can't see it "deforming" with the weight of a ball sufficient to increase the drag coefficient to anything other than just that of the cloth.

So why are MDF tables slower?!

PS, only interested in speed here, I know that for a level play area slate will always be better along with a whole host of other benefits it brings to the table.
Click to expand...

Energy absorption. MDF is less dense, and absorbs much more energy than slate. Any source for vibration, will act as an energy sink. Loose bracing, loose pocket castings, loose rails, etc.. The same principles apply to MDF vs slate
 
Lawnboy77

Lawnboy77

AzB Silver Member
Silver Member
From strictly a speed perspective there would be little to no difference in wood vs. slate for any given cloth stretched over it until the balls contact a cushion. Typically the slate table will weigh much more than the MDF table and it will also have much better cushions and that is where the difference is when considering speed. The livelier cushion combined with the extra weight and rigidity of the frame means there will be much less energy loss when the ball contacts a rail, whereas on the cheaper, lighter table that literally moves when the ball contacts the rail it acts more like a shock absorber and loses energy, and thus speed is lost.
 
T

tjohnson

AzB Silver Member
Silver Member
Consider two extremes: Pool table cloth over polished granite and pool table cloth over carpet. Of course the ball will roll faster and farther over the granite. MDF isn't carpet, but it's also not stone.
 
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garczar

AzB Silver Member
Silver Member
Slate has two HUGE advantages: its ability to me machined flat-n-level and its mass. Wood is not close in either regard. It might be ok for a kid's funsy table but that's about all.
 
T

tjohnson

AzB Silver Member
Silver Member
garczar said:
Slate has two HUGE advantages: its ability to me machined flat-n-level and its mass. Wood is not close in either regard. It might be ok for a kid's funsy table but that's about all.
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And the third advantage is hardness, that is the resistance to being dented or compressed. Stone is harder than MDF.
 
fastone371

fastone371

Certifiable
Silver Member
garczar said:
Slate has two HUGE advantages: its ability to me machined flat-n-level and its mass. Wood is not close in either regard. It might be ok for a kid's funsy table but that's about all.
Click to expand...

Lead has a lot of mass but Im guessing it would not be a good pool surface, Tungsten on the other hand would probably be great. :thumbup:
 
T

tjohnson

AzB Silver Member
Silver Member
fastone371 said:
Lead has a lot of mass but Im guessing it would not be a good pool surface, Tungsten on the other hand would probably be great. :thumbup:
Click to expand...

Good analogy. It's the hardness (resistance to being dented) that matters more than the density/mass. And tungsten is very hard!

A ball rolling on an immovable surface has no idea what the mass of the material is that is underneath it, however the ball is constantly testing the compressibilty of the material as it rolls along.
 
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