Thanks Don, I will give then a call, is this in 4x8 sheets?
Ron
Thanks Don, I will give then a call, is this in 4x8 sheets?
Ron
Super Moderator
Ron,
I'm not sure how they sell "Trex", but the material I've used is designed for bulkheads and is 2 1/2" thick by 8" wide or so and is tongue and groove. In that size it's over-kill for a table top, but I think that in thinner boards it might make a good length-wise first layer for a top; sort of a "sub-flooring". Then you would put the 4x8 sheet of whatever you wanted on top of it; maybe some sort of thick plastic for the ultimate in stable table tops?
The advantage to this I think is that it would be inert enough to not move with temp and moisture changes, and also not sag between cross-pieces on your table like MDF tends to do. MDF also absorbs moisture like crazy if you don't seal it well.
Bill
Bill thanks for the info, I will check and see what the have, this just might might take care of the problem of bowing?
Ron
Trex also come in the same size as a 2x6 up to 20' long. Trex is used to replace 2x6 treated decking . it also come in 1" also for decking.
Bob
Ron,
I agree with Bill on the plastic.
However be careful. Many plastics have problems
with static electricity. If used for a table
top some will attract sawdust and virtually
be unable to wipe off clean. UHMW or plexiglass
may be undesirable. While styrene or HDPE
would be better. Check with the supplier on this.
I am sure that there is an ideal material for this.
There are hundreds to chose from.
They'll probably let you take samples for trial.
Alton
By the way, I don't think styrene comes in
thicker sizes. I would look into HDPE.
It's cheaper than UHMW and seems very
stable.
Alton
Be careful with some plastics that absorb water. Nylon is understood to be one of the worst. The boatbuilders here should know that rudder-stock bushes of nylon need a huge clearance when new.
I stopped by a sign shop near me and took a look at there $89.000 CNC machine, this machine will make coffee...lol, it has a tool changer, material feeder,5hp router,and it still took 2 people to run it.
There table top was 1/2 sheet metal and was tacked to the frame, he put a line on it and there was no gap, he said it has been level for the last 6 years.
I am thinking of doing this? since I am going to build a new table anyway I wonder if this would be the best way?. I can get a 1/2 4x8 for $239.00 and Metal Mart here in town, and weighs 262lbs.
If I was to do this? I could have them make me tracks and set some fences on it to hold material in place?, it would look like 1 big checker board.
I have 20 or so stop locks I use for me table saw and there is no moving them when locked.
Gerald do you think 1/2 is over kill?
Ron
Ron, you are asking a loaded question, but I will try my best:
1. A sheet of 1/2" steel by itself is still pretty flexible, unless it is supported on cross members at about 20" intervals. (my choice of crossbearer would be a 2.5" angle, 1/4" thick with wide flange at bottom (plate resting on thin top edges)
2. Of course the cross members must be connected to solid longitudnal rails with legs to the floor.
3. The plate should only be tackwelded to the cross members. 1/2" long welds at 15" intervals. More welds will cause high stress and bowing.
4. Any other fixtures to the top surface should be screwed/bolted (not welded)
5. The major problem is to find a flat sheet from a supplier. Often steel is coiled into rolls at the mill and the middle-men uncoil & guillotine cut to size (Yes, even for 1/2" thick!). Although the major part of the surface may seem to be flat, you often get some guillotine distortion within 3" of the edges.
6. The type of accuracy that I would expect from such a setup would be around 1mm (1/25") for hollows and bumps, but the twist over the whole sheet can a lot more - depends on your cross-members & a level floor.
7. If I wanted to follow this route, I would probably go for a 5/16" or 3/8" sheet, because it is stable enough and is flatter from the supplier. Also it can be "corrected" (with shims) more easily.
8. I would build the whole table, including the setting up of the SB, BEFORE welding the sheet to the cross-members. Then I would run a dial (clock) gauge in the SB and find the bumps/dips in the sheet and try to shim it accordingly before tacking it into place. If the sheet is not level enough, take it back to the supplier, or find another piece of material than can be surfaced by the SB.
Hope this helps - this is more or less how we build "welding" tables for our metalwork.
I built my table top out of 1/4" steel (laser cut with jig and mounting holes in place), bolted to 2" square tubes on 12" centers. It took a lot of shimming to get it to within .010". I can easily deflect the areas between the supports .010" with one hand.
We'll see how this will affect the quality of cut (I haven't put it to heavy use yet).
I could see going to a slightly heavier plate like Gerald suggests, but I sure wouldn't want to try shimming 1/2"
Posting Permissions
