jig for making table top flat


Hello again! one year and seven months ago I bought a 3x6 Maple tabletop from Grizzly. I don't normally use it for large projects and I haven't checked it for "flatness" in awhile, but this past weekend I laid my level across it and the level rocked(!).Needless to say I was surprised and more than a little bit irritated, it has a 3/16' bow on one end and 1/8" bow on the other.
1) its out of warranty. 2) I don't have my reciept.
I live in a very rural area in western WA. Three hours from a city large enough to have a sander capable of sanding it flat. So, I have to make it flat. I don't own a jointer. My questions for the group are; Does MDF normally have a straight enough edge to use as rails for a router sled? Do I make both sides flat?
In this case "flat" is within 1/16".
Thanks, jaquestion
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"jaq" wrote...

Normal, especially in a damp clime. I buy grizzly stuff, and as long as you consider their stuff to be a bargain that requires some tweaking, it shouldn't be a disappointment.
Take the high spots off with your plane, belt sand the whole top, slap some erl on it, and get back to work.
Rout the top with mdf sleds? That's just crazy talk.
-- Timothy Juvenal www.rude-tone.com/work.htm
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Normally? Well - I guess if you mean does it come from the store with a straight enough edge, then yes. But even if it didn't, you could saw it to a straight edge.

That's up to you.
--

-Mike-
snipped-for-privacy@alltel.net
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
jaq:
One important thing to consider here is how the table is actually sitting. If the feet are not on a level >plane< with each other, it can easily pull the top one way or another while it tries to settle in.
<<In this case "flat" is within 1/16". >>
If you put a level on the top when you got it, and shimmed the legs to level and the top was within a 1/16" after that, you could easily have this problem. Say your top is 1/16" low in one direction, then it sags to pick up another 1/16 in the floor; now you are at 1/8". Then add a little humidity, and you can easily pick up another 1/16". Now you are at 3/16" in total.
But I have seen solid maple tops move 1/8" in 6 feet alone just as humidity and heat (predicted 100 degrees here today) changes with no problem.
If you are that concerned about the flatness on a daily basis, I would recommend this:
Put the table where it will stay for your work. Secure the top as tightly as possible to the legs, and level in place to your satisfaction. Remove the screws from the top and replace with 1/4" lag screws (drill out the holes that hold the top as needed). Drill enough holes to have the screws no more than 12" apart.
Cut an assortment of shims from a hard material like really dry white oak, from 1/16" to 1/4". Put a string line with spacer on each end (I use dental floss for accuracy) and shim as needed before starting a new project. Tighten down your screws as needed to secure the shims and your top will be as flat as you want it.
Wood will react to its environment, and will move as it pleases. Laminated wood can be more stable or less stable, depending on the piece. But no matter what, you should never think that your table top is a piece of granite assuming that once put in place to your specifications it will never move.
Unless you live in a moderate climate with little fluctuation in humidity, or your workshop is a controlled (climatized) environment I wouldn't think of cutting into the table top because of what you are seeing.
As always, YMMV.
Robert
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.