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Pocket hole through MDF to Poplar

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Forum topic by BinghamtonEd posted 185 days ago 667 views 0 times favorited 17 replies Add to Favorites Watch
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BinghamtonEd

1245 posts in 996 days


185 days ago

One of my upcoming projects is going to be a headboard for our daughter’s new room. Nothing fancy, just two posts made of poplar, with a MDF panel between them with some curves routed on. Painted white. Probably will end up covered in stickers and crayon.

First off, let’s get this out of the way :
“MDF.”
Boos and hisses

Now that we’ve done that…

Plan is to have mortises in the poplar posts for the MDF panel to fit into. Since this will be a fairly large panel, I will have plenty of joining surface. I plan on drilling pocket holes in the back of the MDF panel. Put some glue in the post’s mortise, slip the panel into the mortise, and drive some pocket screws in to pull everything tight.

To me, this seems like it will work just fine, as the screws are going into poplar and not MDF. Am I mistaken here? Also, will regular TiteBond give any good adhesion between the poplar and MDF?

Thanks guys!

-- - The mightiest oak in the forest is just a little nut that held its ground.


17 replies so far

View Fred Hargis's profile

Fred Hargis

1716 posts in 1120 days


#1 posted 185 days ago

Though I’ve not tried it, I think what you want to do will work fine…the screws will just be acting as the clamps until the glue dries (and Titebond will work just fine as well). The only risk would be the screws pulling through the MDF, have the pieces closely mated when you tighten them down, once the glue dries it won’t matter.

-- Our village hasn't lost it's idiot, we sent 'em to Washington.

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dbhost

5378 posts in 1858 days


#2 posted 185 days ago

I would seriously consider a different material, or a different construction method. In my experience screws and MDF do not get along all that well.

-- My workshop blog can be found at http://daves-workshop.blogspot.com

View mnguy's profile

mnguy

161 posts in 2024 days


#3 posted 185 days ago

If Fred and I understand your plan correctly, the screws are really holding until the glue sets. I think you’ll be fine, but I would use the washer head pocket hole screws and use a light touch/low clutch setting when driving the screws. I think it would be pretty easy to drive the screw right through the pocket in the MDF.

I also agree that regular yellow glue will work fine. But, you need to size the motise and tenons to hold the joint together; you can’t rely on the pocket screws to reinforce it much, for the reasons above (pull through).

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bondogaposis

2480 posts in 977 days


#4 posted 185 days ago

How thick is the MDF? I think it will work but will only be as strong as the MDF, which is not very. Don’t plan on this being an heirloom.

-- Bondo Gaposis

View JAAune's profile

JAAune

775 posts in 943 days


#5 posted 185 days ago

That technique will work fine as long as you don’t over-torque the screws. I’d recommend spreading the glue, applying a few clamps to pull everything tight then driving all the screws. Place the screws a maximum of 6 inches apart. The clamps can come off as soon as the last screw is in.

I’m guessing you want to use the screws as clamps because you don’t have long enough clamps to do the job. That’s fine but it’s not as fool-proof as clamping first so you’ll just have to be more careful and you’ll want to use more screws.

Washer head screws will work best since they’ll deform the MDF the least.

I’d recommend soaking multiple applications of either epoxy or polyurethane into the edges of the MDF after the glue up to solidify them. That will prevent crumbling or flaking on the edges. Sanding comes next followed by primer and paint.

-- See my work at http://remmertstudios.com and http://altaredesign.com

View GOOD LUCK TO ALL's profile

GOOD LUCK TO ALL

418 posts in 354 days


#6 posted 185 days ago

I would skip the pocket screws and just toe nail the mdf into the poplar with some pins.

View Dallas's profile (online now)

Dallas

2866 posts in 1113 days


#7 posted 185 days ago

The MDF will work, but in my (not worth much), opinion, the top and bottom edges of the MDF will be subject to a lot of wear, tear and damage. It would be much stronger if you cut a dado into the posts and using a top and bottom rail with dados also cut in. You could cut through mortices and use the top and bottom rail as the tenons.

-- Improvise.... Adapt...... Overcome!

View 404 - Not Found's profile

404 - Not Found

2544 posts in 1595 days


#8 posted 185 days ago

Put a tongue on the mdf and a groove in the posts, and use plenty of glue. I don’t think the pocket screws will add much strength to the construction. In my experience, the threads tend to strip poplar easily. If you are going to go this route, use longer pocket hole screws with a coarse thread.

View CharlesA's profile

CharlesA

1212 posts in 424 days


#9 posted 185 days ago

Haven’t done it in a while, but if you have the clutch set right on your driver and you use the coarse screws, pocket holes in MDF work just fine. I built an electric piano stand 12 years ago with that method, and still is very stable.

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson

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dawsonbob

381 posts in 382 days


#10 posted 185 days ago

Just out of curiosity, how much more expensive would it be to use plywood instead of MDF?┬áIn this situation it would seem to me that cheap plywood would be a better choice. I’m a newbie, so I may be way off base.

-- Mistakes are what pave the road to perfection

View Dallas's profile (online now)

Dallas

2866 posts in 1113 days


#11 posted 184 days ago

CharlesA, I just can’t resist….... Why do you have to plug the piano stand in?

I should hate myself!

-- Improvise.... Adapt...... Overcome!

View Bob Current 's profile

Bob Current

310 posts in 244 days


#12 posted 184 days ago

I think “Dallas”s idea is very good advice. I’ve not had that good of luck with MDF or particle board in a structural position. His idea makes the MDF in fill and somewhat of web as I understand your project.
Enjoy your project.

-- When you are wrong admit it, when you are right forget it.

View Vincent Nocito's profile

Vincent Nocito

424 posts in 1990 days


#13 posted 184 days ago

If you can lay your hands on MDO (medium density overlay) use that. Since you are planning to paint, MDO take paint nicely and it will hold a screw better.

View GOOD LUCK TO ALL's profile

GOOD LUCK TO ALL

418 posts in 354 days


#14 posted 184 days ago

Why do you have to plug the piano stand in?

Better yet, why do you need a stand for your piano, don’t they come with legs?

View CharlesA's profile

CharlesA

1212 posts in 424 days


#15 posted 184 days ago

-- "Man is the only animal which devours his own, for I can apply no milder term to the general prey of the rich on the poor." ~Thomas Jefferson

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