MDF question

[peter slamp]

So in my effort to constantly be evolving my meager skills, I've decided to try a veneered table top. I've decided on mdf for the substrate and plan on framing it with some hardwood. I'm curious as to how I would attach the top to either legs or aprons. I thought I had read that screws don't work well with mdf. Is glue an option? Also when attaching the mitered frame is glue an option or should I rout a recess for the mdf to sit in? I plan on gluing some nice veneer onto the show face of the mdf, do I need something on the other face as well? Also, lastly, is contact cement the choice for the mdf/veneer interface? Thanks alot! ;)

[frank shic]

screws will work fine for attaching an MDF tabletop to the legs and aprons. MDF does not expand or contract appreciably and you probably aren't going to be picking up the table too frequently. i have a round dining room table that's veneered MDF approximately 50" in diameter (try to find a tablecloth for this monster!) and it's fixed to the pedestal below with screws.

[Brian Dormer]

In my experience, the biggest challenge in getting MDF to stay together is using the right screws. I use the KREG pocket screw system as well as using the KREG screws by themselves (known in the shop as the "screws of the Gods" because they work so well). Alternativly, use CONFORMAT screws, which are specifically made for MDF. NEVER use old-fashioned wood screws - especially in end-on situations - you'll spit it.

Finally, anytime you are close to an edge, MDF will have a tendency to bulge if you don't predrill. It also helps to clamp where you intend the screw to go to prevent bulging.

[Matt Lentzner]

In my experience, the biggest challenge in getting MDF to stay together is using the right screws. I use the KREG pocket screw system as well as using the KREG screws by themselves (known in the shop as the "screws of the Gods" because they work so well). Alternativly, use CONFORMAT screws, which are specifically made for MDF. NEVER use old-fashioned wood screws - especially in end-on situations - you'll spit it.

Finally, anytime you are close to an edge, MDF will have a tendency to bulge if you don't predrill. It also helps to clamp where you intend the screw to go to prevent bulging.

I assume you are using the coarse thread screws in MDF. Correct?

Thanks,

Matt

[Jim Tobias]

Peter,
I have been doing a couple of vennered panel tables like you are talking about and I believe you are better off routing a recess for the MDF (with veneered face and back ) to sit in. It supports it better and you then are not concerned about screws holding in the MDF. A picture below of the underside of the table. Use the figure 8's to hold your top on.
Also, from my own experience and from all I have read, you are less likely to have glue problems if you use a urea resin glue(Unibond 800O . It is very simple to mix and they have 3 different color levels of the mix (light, Medium and dark). They also have a blocker that you can put in to prevent so much bleed through which helps with sanding afterwards (and who doesn't love to eliminate some sanding). Check out VacuPress.com

Jim

[Mike Holbrook]

If you need to use any screws in the MDF you might check out the McFeely's sight for more information on the confirmat type screws.
http://www.mcfeelys.com/subcat.asp?sid=399

In a real tuff situation there are barrel nuts that can be installed in drilled holes in MDF pannels. The barrel nut provides a metal threaded reciever for matching connecting screws. http://www.mcfeelys.com/product/0612-CDA/-20-x-34-Offset-Barrel-Nuts

In Europe where particle type woods are used more frequently, these types of fastners are well known, they are not as common here in the US but McFeely's carries a pretty wide assortment. McFeelys site is worth reading through just for a better education on screw/fastner types and their appropriate uses. I have to check back there regularly just to maintain a modicum of knowledge regarding the growing assortment of fastner options.

[Greg Deakins]

you are laminating the top, so drive your "coarse threaded" drywall screws down from the top into the legs, then laminate over them, otherwise the concept is good...

[Bert Johansen]

Peter,
MDF works great for veneering. You don't need to do anything fancy in the way of glue. Last year I finished a desk with a veneered maple top, with a hardwood surround. It is 60 x 26, and is laminated onto a single sheet of 3/8 MDF. Just yellow glue to adhere it, one side only. (But I spent half-an-hour with a laminate-style j-roller making sure all the air bubbles were out.)

I did, however, glue poplar cleats to the bottom where I attached the top to the web frame. That way I didn't have to worry about screws in MDF--see photos below. I also included a shot of the frame corner which has a stopped spline miter to give the frame strength.

[peter slamp]

Thanks all for the help and guidance. This forum is polarizing for me. On one hand, I love it because of the great people and knowledge. On the other hand, I hate it because everyone's work on here is bad for my ego! ;) Oh well, it certainly has given me much to aspire to.

[Jude Tuliszewski]

I also would make sure that when you put on the top coat (poly or what ever) that, the seams where the hardwood edging meet the MDF (even if very tight), are sealed well so any spills will not wick into the MDF. If the MDF gets wet it will swell and not return to flat.:(

[Jim Tobias]

Peter,
I would also suggest that you might want to check out the sights below or do other searches about veneering a top panel and info on glue types and the importance of veneering the back side of your top.

Just for info.

Jim

http://www.sawmillcreek.org/showthread.php?t=47982&highlight=veneer+panel+glue

www.joewoodworker.com

http://www.wood-veneers.com/veneer_adhesives_act.htm

[peter slamp]

Peter,
MDF works great for veneering. You don't need to do anything fancy in the way of glue. Last year I finished a desk with a veneered maple top, with a hardwood surround. It is 60 x 26, and is laminated onto a single sheet of 3/8 MDF. Just yellow glue to adhere it, one side only.

Is this ok? I thought yellow glue would be fine as well, but no site that sells veneer adhesive list yellow glue. Also, I thought I heard that you should always veneer both sides. That table looks really great, so you must know what your talkin' about. :)

[Guy Germaine]

I made this by just gluing the aprons to the top. It's long grain to long grain, so it's never going anywhere.

http://www.fototime.com/C4292AF0AEE36C8/standard.jpg

[Brian Dormer]

I assume you are using the coarse thread screws in MDF. Correct?

Thanks,

Matt Yes, you use coarse thread in soft wood and MDF and fine thread in hardwood. bd

[peter slamp]

Can someone straighten me out 'cuz I'd like to start the veneering part of my project tommorrow. On one hand Bert obviously does amazing work and he says just use yellow glue on mdf. A bunch of other stuff I read says don't use yellow glue, but most glues specified appear to work with some vacuum system which I don't have. Also, Bert says don't worry about veneering on both sides yet all the links I followed say do both sides. Can someone clear this up for this rookie please! :rolleyes:

[Jim Tobias]

Peter,
I guess my last piece of advice is that you might get by with yellow glue and not veneering the back side of your panel. I think what you have been reading on the veneering web sites is sound advice. If you don't want to take a chance on your panel, don't use yellow glue and also veneer the back sdie of your panel.
There is a reason that you are reading about this on the veneering web sites. It is because a lot of these guys have probably learned the hard way and had a project go bad. My bet is that you decrease your chances of glue creep and moisture problems from the backsise if you use the best glue for the project and veneer the back side to stabilize your panel.

Jim

[Guy Germaine]

(Don't let your wife read this) :D
You don't "need" a vaccuum press to glue veneer down. You can glue it down using clamps and cauls, or you can use LOYL's iron and iron it on. On the table I posted above, I used an iron to put the veneer on.

However, I did just take shipment on the veneer press that Woodcraft carries. (Semi-Stealth Gloat :D:D )