Grinding imperfections

[slk3q]

Looks pretty slick!! I'm putting a new table together and would like to try this. I think I understand what you meant by leveling in a RELAXED state. Do you finish/glue the slate seams before starting the blocking process?

 

[DaveB1]

I worked in a Granite and marble Fab shop and you would be surprised at the uneveness of the slabs we were working.(Crown's etc.)


Dave

 

[sparkless]

Use a good fine filter, or the dust will shoot out the other side! I smoked out a pool hall by using a poor vac once, woops. As far as taking off too much material by grinding or honing...You have a good 1/8" of clearance in the rails so that shouldn't be an issue. The worse slate I have honed down has been trouth to peak variance of about 0.020" though I am certain worse are out there. Taking the top 0.01" of a crest down will make a very noticeable difference in playability. Perfection is a theory, excellance is the closest you get. Always a better way. BTW, How long has Gabriel's been doing this to thier slates?

Wanna see something cool, research Granite hole saws from Egypt.

i have a 5x10 1 1/2" slate brunswick arcade. just checked it with an 80" straight-edge in two different places. the maximum peak to trough measurement appears to be between .001 and .002 inches. would blocking the slate help?

 

[goldcrown4]

... Perfection is a theory, excellance is the closest you get.

Great quote!

 

[TableTek]

i have a 5x10 1 1/2" slate brunswick arcade. just checked it with an 80" straight-edge in two different places. the maximum peak to trough measurement appears to be between .001 and .002 inches. would blocking the slate help?

Not to be a naysayer, however a 0.001 variance over 80" is beyond the tolerances I used to hold making carbon bearings for jet engines! I would say any variance under .005 over a given linear ft of slate is excellant. Blocking lightly will always show machining marks, it cannot however take down a full slate crown so that must be fixed in those cases prior. One of the most common fixes it is used for are the "earing" effect of corner pockets. Want to see a poor slate grind, block a 3/4" unbacked set sometime.. You'll be able to tell the radius used by grinder at the seams very visibly!

As I tell customers these days "it'll only get as level as it is flat"

Hope this helps

-Rob

 

[goldcrown4]

Looking for any updates, especially from readers that are first-timers using the granite machine plates to sand down their slates, and an answer to someone's question above about whether or not to level, glue/bondo slates before starting the lapping process.

I'm also wondering if a block of sandstone that meets the same dimensions would work. I don't know what grit the surface would naturally be at, but it could very well be around the 60 grit mark, and then one would never need to apply sandpaper. To keep dust down, spray some water on the slate, no? It may be the sandstone's density, modulus of rupture, and moisture absorption may be prohibitive to the ideal that granite provides?

 

[Majic]

Looking for any updates, especially from readers that are first-timers using the granite machine plates to sand down their slates, and an answer to someone's question above about whether or not to level, glue/bondo slates before starting the lapping process.

I'm also wondering if a block of sandstone that meets the same dimensions would work. I don't know what grit the surface would naturally be at, but it could very well be around the 60 grit mark, and then one would never need to apply sandpaper. To keep dust down, spray some water on the slate, no? It may be the sandstone's density, modulus of rupture, and moisture absorption may be prohibitive to the ideal that granite provides?

I tried it on my personal table. The results can't be denied, but the process is messy. The sandpaper loads up quickly and needs to be unclogged frequently. I used a strong bristled brush to unclog the sandpaper and a work bench brush to move the majority of the dust from the table before vacuuming. Use high quality sandpaper and not the stuff from Harbor Freight. Having the seams filled with Bondo will work, but should probably wait to apply the Bondo until you have the table as flat as you want it first then Bondo.