Slate levelling

[capella166]

Hi everyone, I have a second question today concerning my snooker table installation,

I would like to have your experience about how straight a table should be ... Or I must say realistically be, depending on many factors ...
Ideally, each slate would be a perfect plan (no sag, warp or others) and the five of them would form another perfect plan together all perfectlly level.
That way, a perfectly balanced ball would run perfectly straight from anywhere to anywhere on the 6x12 slate, even at very low speed... That is probably asking to much...

So before to put the cloth on, I would like to know if my leveling can still be improved or it's about as good as it can be for an amateur installation...

Can anyone give me a general idea of what kind of roll out from a straight line I should expect when I let some ball roll on the slate without the cloth.
I expect that this roll out will be minimized, later with the addition of a cloth installed in the state of the art. I would prefer to continue the levelling before to put the cloth on and discover that it's not good enough...

For now, I'm using a machinist level to check the level, I used it also when I first assemble the frame and place shims under the legs...
I seen that the level used by snooker table fitters are different and I dont know their precision...
I wonder if my level precision is too much compare to the kind used by pro fitter...

The machinist level I got is a 10 inchs long and has a resolution of 0.0002'', or 5 micometer per division. It has a total range of 8 divisions so it can read about 20 micrometer slope on each side and I can still add about the same range to extrapolate (without divisions) before it maxed out...

I dont have a 6 foots straight edge to check the straightness of the slates, but I have a 4 foots aluminium ruler that I checked and is pretty straight (within 50 micrometer).
The slates seem to be within 50-75 micrometer using feller gage, except for the joint, which can be at some place at 100-125 micrometer.

Around 75% of the area of the slate I checked with the level are within 40 micrometer one way or the other from being perfectly level, but some area are ''maxing out'' the reading.
When I first get the level, I had to adjust it. when I place it on a section perfectly level and turn it 180 degrees, it still perfectly level, which tell me I adjusted it correctly.

Having said that, some sections of the slate are perfectly level, and some section of the same slate are not and maxed out the reading, which tell me that the slate itself is not perfectly straight...
The same thing happen on the 6 foots axis, the middle part are perfectly level, but the two extremity are not. It look to have a banana shape from the level reading with the low point on the center.

The middle slate dont make the banana. The pink and black ball slate are the worst with an estimation of about 150-200 micrometer higger that the perfectly level center.
At first, I tried to place a playing card under the slate, in the middle and it seem to work, as I got a nearly perfect reading all along the 6 foot width slate.

I was worring that the wood under the playing card would give up with time, and in a week time it happen has the banana shape cameback on the slate. I know that there is some bracket to help adjust this, to put under the table, but I wonder if it would be usefull as they also fixed on the wood that support the slate. I noticed that the wood rafters that support the slates (not the main exterior frame) are not all in contact with slate, which dont help, but I can not do that much because they are fixed with tenon and mortise and there is no loosse ...

I tried to write a good resume of how my table actually behave and if any of you have some guideline to tell me about how straight a table should be before to put the cloth, I will be happy.
I also would like to know what is the smallest shims thickness you use to place under the legs or slate, it will give me an idea of what kind of precision is required...

Eventually, with the cloth on, I will use my 4 foots straight edge to line up 4-5 balls and gentlly hit the first one with the white ball to see how straight the last one roll...

Thanks very much to help !!!
Have a nice day !!!

[Danger Steve]

I’ll try to help where I can starting from the beginning and based on my own table fitting experience.

Firstly before fitting the frame together I left out the dowelled ‘muntins’/ central frame timbers. You can cut the wood dowels off with a saw, buy a set of ‘slate support brackets’ or weld up your own from steel plate (probably stronger this way if your good at welding). You’ll then have to stagger the muntins when you re-fit them with the bracket because of the holes in the frame where they use to live. Next you want to position the table exactly where you want it to be when finished and get the frame roughly level by packing the legs, don’t spend ages levelling at this point. Make sure you identify the lowest leg and leave this in contact with the floor (do NOT pack this leg ever), this will be your starting point to level from. Once it’s somewhere near level you’ll probably have to plane both of the long side rails to get them flat ready for the slates, don’t go crazy with the plane though! Just a quick once over to get a nice flat surface. Next fit the slates and position them evenly on the frame, don’t fill the joints just yet. Now using your long straight edge with the machinists level on top check the level of the table starting from your highest leg identified earlier. Work your way down each side one at a time, add packers under you long straight edge ( between the slate and level) until you have each length reasonably level when sat on the packers. Then if you can get a 6ft straight edge check across from one side to the other... once you’ve got it close jack up the table from the middle of the side rail only (not the ends) and place the packers on top of the slate under each corresponding leg. Once you’ve done this on both sides go round again and double check everything is OK, I push down on the slate above each leg just to help settle them in a bit quicker... After all this you should now have slate joints that are near perfectly flat with each other at the edge of the table? If they have a small step all in the same direction then you need to start again from you base leg and re-level, don’t be tempted to cheat and pack individual slate edges with pieces of card it will just transfer the problem to the other side of the table. Check the joints in the middle once you have the edges flat and level across one side to the other, if some are perfect at each end but you have a little step in the middle then the slate is slightly dished, you can now insert pieces of thin card (playing cards) between the underneath of the slate bed near the joint and the muntins (your centre muntins should have been wound down out of the way up to this point as to not interfere with the previous levelling of the edges). Insert the card under the lower slate and then begin tightening the brackets slowly and this should hopefully cure the step by jacking the middle up the thickness of the card, or at least reduce it to a slight bump that can later be filled and sanded/feathered out...
Once all this is done, have a quick check of level using just the machinists level, accuracy is OK at 0.02.

At this point depending on the floor type the table is sat on I would probably leave it for 24 hours and come back and re-check the level. It’s a waste of time running balls on the bare slate to test if they run straight from corner to corner because the way slates are floated leaves a slight textured surface which effects the way balls run on that surface. At this point you just have to trust your levelling is accurate... Once your happy you’ve got it as level as you can without going insane, you can now fill the joints with a fine soft sand car body filler. If there are any chips in the slate joints make sure to fill and sand those too! Give the slate a good wipe down and your ready for cloth!

[capella166]

Thanks for the detailed answer Danger Steve, I really appreciate the time you took to answer and I wanted to fully understand the technic you described to me. So, I made a resume to be sure I don't miss something as on my first 2 readings, I miss understand a point. Hopefully, I hope I figured it all right and you just have to read it ... I break it down in part to make it easier to assimilate.

First work with external frame, no muntins central frame timbers.
Get rid of the dowels on the central muntins and make some metal bracket to hold them. At this point, I will probably pass them on the jointer and planer to get them perfectly straight as it's a table from the 60's or 70's.

Carve the muntins where the homemade bracket will be sitting.
Level the bolted main frame without the central muntins.

Find the lowest leg (or highest as you describe later, anyway the one that will stay on the floor), and leave it on the floor, unpacked and use it as a starting point.
Plane long side frame (only if the straight edge tells me it's not flat).
Place the slate to their final position without filling the joint.

Using the lower or highest leg (not sure how you referred to it), but we talk about the one that sit directly on the floor, put the level on the straight edge siting on slate in the long rail direction. The best things I founded as a long straight edge are two 8 foots aluminum U channel profile. I selected those 2 within 30 others because, on store, when I placed them side by side, on the axis they don’t have to support their own weight, I could not insert a 40 micrometer shim between them... So, they are the straightest thing i founded at a reasonable price. The problem I founded with them is that with the level on top, they bend a little bit, I don’t remember how much ...

If I understand the technic you explain to me, by packing shims under the straight edge, working my way down the longs rails first length by length (like by 6 inches or 12 inches steps), keeping the best level as possible, I will find the missing thickness between the legs and the floor. Using the thickness that is on top of the corresponding legs, I will eventually insert that thickness under the corresponding leg. Is that's why my main frame top must be as flat as possible??? The support under the straight edge (the build of pack of shim that keep the straight edge level) will also solve my problem that the straight edge is bending with the weight of the level on top.

So, after that, I will have found the correct thickness missing for the two longs side. I will need to check it also on the short sides and compensate also for that missing thickness. Then, jacking the table in the middle of the long rails, place the shims under the corresponding legs.

Repeat the step to double check later to let the table/floor stabilize.

So, now the perimeter of the table must be level and if the center/joint are not level it's because slate is warping a little bit. So, I should never place any shims between the frame/muntins and the slate unless the slate is a bit warped if I understand well?? Which may be my case...

The muntins must have been lower than the rest of the frame during the previous alignment procedure.
Use the bracket to force the slate to bend back to a straight level in order to level the warp slate and level joint. I guess this is only for small dished slate, like 100-200 micrometer.

Accuracy 0.020 is in mm I assume, so about 1 mils.

Then fill the joints, sand, clean and install the cloth, mark line, install the rail/pocket and finally play and enjoy!!!

Hopefully, I figure it correctly or mostly correctly.

So, thanks again, I will continue to work on it slowly during the Christmas time. I also have to make some wood strip for tacking the cloth as I throw away the original one because some were broken…

I also want to make a napping block to give the best chance to my old cloth…

Thank very much for now!!!

Have a nice day

[mikee]

Steve pretty much summed all this up perfectly ,I will say after watching Geoff Large work on my table and check the levelling ,It doesn’t matter how level you get the slates once the cloth is fitted you are chasing the impossible ,as the cloth has too many variables ,including nap . 95% level is perfect with cloth on ,make sure slate joints are flush and filled perfectly ,let the table settle before final checking ,balls running slowly across the nap will always behave oddly sometimes over long range ,as long as balls don’t roll to the middle ,dished slates ,or roll away from the cushion rails then you are good to go if you are happy with the level . Just watching snooker on the tv you will always see plenty of times balls moving off in frames ,it happens regularly ,finger marks , dirty balls all can make a difference too .There is no such thing as a perfectly level full size table ,as long as the slates are good ,the frame is level and adjustable muntins are used to keep the slight pressure under the middle of the table ,you should have a good enough playing surface .

[Danger Steve]

Just to confirm some of your questions there capella166

Put the whole frame together including the now sawn off muntins sat in there new adjustable brackets, just leave the muntins down below the height of the side rail so they don’t interfere for now. Find the leg that is highest point on the frame when just sat without any packing and that will now be the starting point. What I did was just go around the frame above each leg with a straight edge and level on top, push packers under the rest as required directly above each leg until I had the whole table pretty level. It’s easier doing this when on your own than having to keep lifting the frame up and placing the packers under the legs and then keep getting up and down to check the level.

If the U channel bends with your machinists level on top then that’s not going to work, I have a 6ft aluminium spirit level which is nice and flat under its own weight, it has its own bubble/level but with your machinists level sat on top that will make it more accurate.... A good way to test if your level is accurate is to place it on the table one way then spin it round the other way (180 degrees) and the level should give you the exact same reading, if not then the level itself isn’t calibrated correctly.

It can be tricky sometimes to get both sides level with each other, had it where I got one side level, then levelled the other side but across from side to side at one end the slates where out of level. This usually shows up on the 4 slate joints near the edge, they might be level from one end to the other but each slate joint had a small step. This occurs when the table is not quite level across and creates a twist in the slate. It’s tempting to put a thin card packer under each of the edges (pack between side rail and slate) that is lower but all this will do is transfer the twist to the opposite side. Another tip when you have packed the legs, give each one a little jiggle low down near the floor, they should all be solid! If you have one that you can actually move then this legs is actually floating! Once you have each side rail pretty level (don’t worry if there not perfect, as Mikee said it’s near impossible to get it all perfect). And each side is level with each other and the edges of the slate joints are flat across (give or take the odd small amount that can be filled and sanded). Then at this stage you now want to check the middle slate joints are flat! If you have a step in the middle you can put a shim between the muntin and the slate and then tighten up your muntins brackets. This will do two things, firstly it will help give support to the centre of the slates and secondly with the piece of card in there it should remove the step. Don’t go crazy tight with the muntins, you don’t want to try to actually lift the slate from the middle, your just supporting them from future sagging. When tightening alternate between the two bracket adjusting them upwards a bit at a time until they sit flat up to the slate.

Don’t forget to fit the cloth with the nap running from baulk end to the black end, also the cushion cloth should have the nap running the same direction! At the baulk end the cushion nap runs from yellow side to green side and at the black cushion end, from green side to yellow (mirror image of the opposite end).

Good luck with it! And don’t forget to put up a few photos so we can see your progress!

[capella166]

Wow, thanks very much again... I'm over the moon with all those details and tips you gave me on how to level a full size table...

I will work on this during Christmas and between New year Day...

For this time, I wont be able to remove the muntins because I'm alone to move the slate due to pandemic restrictions and because to weld the bracket, I need to work outside and it's winter here and snow start to build up.... I don't want to use the welding machine outside in winter, it has to be on the summer...

I will do this when I will put a new cloth on with the help of a friend for moving the slate...

But I will surely use your method to fine tune the level for sure and get the best from the table for now...

I will post some picture when I will end some steps to show progress and the result I achieved...

Yesterday, I tried to upload a picture of my level and the used cloth, and I didn't found how to do it...

I think I have to put the picture on the net and then upload the link... Does the site allows to upload pictures directly on it ??? From the choice it give me it look like only hyperlinks can be uploaded...

It's my first few post on the site, so i'm not sure...
Either on my computer and cellphone, when I publish a message, I get an error message but the system still post it apparently...

I have to contact an administrator also and even if my notifications seems correctly set, I don't get any when people reply on my topics .... Anyway... it's questions for the site administrator...

Thanks again and I keep you updated...

Have a nice Sunday evening especially if you watch the Grand Prix final tonight...

[DeanH]

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[capella166]

Thank very much DeanH, those were the questions I needed help !!!

Have a nice evening

[capella166]

Thank very much DeanH, those were the questions I needed help !!!

Have a nice evening

[capella166]

So I will try to upload a picture of the used cloth and the machinist level I got...

[capella166]

[philip in china]

I have a digital level. That shows my table as being dead level. The digital level will turn to the thickness of a new bank note, so that is how accurate it is.

Interestingly when I really was in China I had a table set up twice (I moved). Both times the guys never used a level. They had a long rubber tube and used the level of water in the tube. Both times the table played well so the system obviously works but I am sure a good level is simpler.