steel bars bolted to underside of table top - why?

[fobos8]

Hello all

I think this is the thousandth post I've made table tops and I'm still going strong!

I just finished making a oak table top (900 x 1600 x 45) and I'm wondering if I should be adding grooves and steel bars to its underside.

I just look underneath my dad's table (1800 x 1800 x 40mm) and noticed that there are grooves parallel to the boards and that there are also two 40 x 8mm steel plates running at right angles to the boards and coach bolted to each board.

Why were these added to his table? Why are they not on all tables? I've looked underneath others and not seen them.

Do I need to add them to mine?

Best regards,

Andrew

 

[Ironballs]

I'd need a picture to understand what you're describing

 

[johnf]

I would think they are there to stop any movment as it a large table top 1800x1800

I think it 's a bit industrial though

 

[jlawrence]

hmmm, I wonder how that would work in a home environment.
Wood moves throughout the year. If you tie it completely in place then what will happen as it expands/contracts. I'd suspect that, unless it is in a perfect environment (or sealed exceedingly well), it would end up looking like a wash board.

 

[jasonB]

They are to stop the top cupping but still allows expansion & contraction

I have seen it done with 25x25x3 steel angle where a 25mm deep x 3mm wide groove is cut into the top so the angle fits completely into the top, this is far more rigid than flat plate. You also must have slotted holes to retain the steel.

Jason

 

[fobos8]

thanks for the replies.

sorry I didn't post a pic goldenballs. Don't have a website to upload one.

I've been looking into table top cupping and its prevention and have decided that by fixing the top to the rails using cleats and slots it will be fine.

I think the reason my dad's table has the steel plates is because it was probably stored prior to sale with the table top separate to the base. I which case the was no fixings to prevent cupping.

Best regards, Andrew

 

[MikeG.]

sorry I didn't post a pic goldenballs. Don't have a website to upload one. Andrew

Andrew,

you must get to grips with this!! You don't need a website.....simply join Flickr or Photobucket or one of the other free sites. You resize your pictures using another freebie (Pixresizer), upload to Flickr, say, then paste the URL into your post. Bingo.

It is simple.......and compulsory! No more excuses now.....

Mike

 

[Ironballs]

Goldenballs!!

I agree with Mike, I'm no techie but Photobucket is dead easy and allows you to load pics in different sizes - and will tell you what is a good size for forum pics