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Best way to attach apron to MDF bench top?

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Forum topic by BinghamtonEd posted 11-20-2014 02:19 PM 1977 views 0 times favorited 30 replies Add to Favorites Watch
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BinghamtonEd

2281 posts in 1835 days


11-20-2014 02:19 PM

So I managed to score some hard-to-come-by time in the garage tomorrow afternoon, about 3 hours, and my goal is to get an apron on my workbench. The bench top is 2 layers of 3/4” MDF, with a replaceable 3/16” hardboard top. It sits on top of a 90”x21” span of cabinets I made. The top itself is 96”x24”.

My plan is to purchase a 12-foot 2×12 of douglas fir, if I can find one with the pith in the center, then rip 3” or 4” wide boards from it. If I can’t find a good 2×12, I’ll adjust my approach to use what good lumber I can find. I will wrap the top in that, and my face vise will have the rear jaw behind it.

Here are my questions :
I am going to be drilling 3/4” dog holes in the top. A couple rows front-to-back for the vise, and a row down the front for wonderpups, bench dogs, etc. No holdfasts or anything that will need to be pounded in. I’ll be making a jig to make sure they’re vertical and equally spaced.

Options :

1 .) Ideally I would have the MDF top overhang the cabinets by 3”, and drill the holes in the overhang, 1.5” out on center. My concern is having them in the 3” of unsupported MDF, however 3” is not that much.

2.) Drill the dog holes in the apron, however I’d need to double up the apron on the front, and I’m concerned that putting stress on the apron repeatedly, where it isn’t supported, will eventually cause the apron to work loose from the MDF.

3.) Trim the MDF back, flush with the cabinet front, so that the dog holes are over the inside of the cabinet. I could easily put in a guard so shavings and dust don’t fall into the drawers below. The apron would be flush with the cabinet, but I could still clamp to it as I chose to leave the top drawer slots empty since the apron would overhang them.

Second question :

What’s a good way to attach this apron? I could just glue/clamp. I also have a partial box of #6 SPAX MDF screws that could help as an extra set of hands to keep things aligned. I have a biscuit joiner. I do not have a bit to cut a groove for a spline. I’m thinking the glue and screws should be sufficient if the apron isn’t being used for dog holes as well.

Enough rambling. Thoughts?

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


30 replies so far

View CharlesA's profile

CharlesA

3023 posts in 1263 days


#1 posted 11-20-2014 02:25 PM

If I understand what you’re trying to do, this sounds like the ideal application for pocket holes.

-- "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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Smitty_Cabinetshop

13738 posts in 2084 days


#2 posted 11-20-2014 02:26 PM

Interested to see how mdf survives as a dog hole medium.

If you’re wrapping the top in 2x material, you shouldn’t have an mdf edge, especially if the top is flush with the front. I’d still make the overhang of pine if you wanted that clamping edge, a good idea with no holdfasts planned.

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive --

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ChrisK

1809 posts in 2547 days


#3 posted 11-20-2014 02:27 PM

The 3” of unsupported MDF will be pretty strong. An apron is a good idea to help protect the edge of the MDF. The edge will get banged up. You can use glue and biscuits, rabbit the apron and glue it to the top. Glue and pocket screws can work, though the pockets should be in the MDF.

I am using 1/2” MDF on top of 1/2” CD plywood for an assembly/run out table. I rounded the top edge over with a 3/8” R. It has held up pretty well over the last 5 years. I used what ever leftover polyurethane I had on hand to finish it. The 1/2” stock is also what I had on had. I want to remake the table with a 1-1/2” thick top to make it more stable.

-- Chris K

View BinghamtonEd's profile

BinghamtonEd

2281 posts in 1835 days


#4 posted 11-20-2014 02:36 PM



If I understand what you re trying to do, this sounds like the ideal application for pocket holes.
- CharlesA

I do have a Kreg jig, I could screw from the top and bottom through the MDF into the apron. That Seems like it would be pretty easy as long as I laid out the position of any holes beforehand.


Interested to see how mdf survives as a dog hole medium.

If you re wrapping the top in 2x material, you shouldn t have an mdf edge, especially if the top is flush with the front. I d still make the overhang of pine if you wanted that clamping edge, a good idea with no holdfasts planned.

- Smitty_Cabinetshop

Correct, there will be no exposed edge, it will all be wrapped. The 3” overhang I was talking about would be the overhang on the front, the top is currently 3” deeper than the cabinet base. It seems from various reviews that dog holes in MDF are pretty durable so long as you keep in mind that they are in MDF. That’s why I won’t be using holdfasts, and I have the hardboard top which will bear some of the abuse. Nothing is going to get clamped down crazy tight here.


The 3” of unsupported MDF will be pretty strong. An apron is a good idea to help protect the edge of the MDF. The edge will get banged up. You can use glue and biscuits, rabbit the apron and glue it to the top. Glue and pocket screws can work, though the pockets should be in the MDF.

I am using 1/2” MDF on top of 1/2” CD plywood for an assembly/run out table. I rounded the top edge over with a 3/8” R. It has held up pretty well over the last 5 years. I used what ever leftover polyurethane I had on hand to finish it. The 1/2” stock is also what I had on had. I want to remake the table with a 1-1/2” thick top to make it more stable.

- ChrisK

Chris, to be clear, I have a 1.5” thick MDF top. I am making the apron 3” thick, but the MDF portion is only 1.5” thick. If I were to leave the top as-is, it would overhang the base by 3”, and I would have dog holes in 1.5” of MDF in that overhang.

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

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ChrisK

1809 posts in 2547 days


#5 posted 11-20-2014 02:42 PM

I understand what you are trying to do, the overhang of 3” of the 1-1/2 thick mdf will be strong and stiff. The edge is soft and I would cover with an apron. I am not sure how well the hole will take repeated pushing from the bench dog. You might want to inlay a piece of hardwood in the top to better support the bench dog.

The pocket holes through the mdf into the apron with glue will hold the apron for a long time.

-- Chris K

View BinghamtonEd's profile

BinghamtonEd

2281 posts in 1835 days


#6 posted 11-20-2014 02:49 PM

I think I agree with the pocket screw idea, Charles. I like Chris’ idea for an inlay strip, although for the time being I’m going to just use the MDF/hardboard, mostly for the sake of just getting this done tomorrow. If the MDF looks like its starting to wear out over time, I can always rout the top and glue a strip in. I’m building this bench as a baby step to a better bench. I’m in no way under the impression that I’ll be using this top for more than a few years.

Once I get this top done, I’ll be giving my old bench, a 2×4 Basics kit, to a friend of mine who needs one, and I’ll have a place to store my larger mobile tools. I’m hoping to surprise my wife by allowing her car to park in the garage for the first winter in 3 years.

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

View mramseyISU's profile

mramseyISU

419 posts in 1011 days


#7 posted 11-20-2014 03:35 PM


Interested to see how mdf survives as a dog hole medium.

If you re wrapping the top in 2x material, you shouldn t have an mdf edge, especially if the top is flush with the front. I d still make the overhang of pine if you wanted that clamping edge, a good idea with no holdfasts planned.

- Smitty_Cabinetshop


I’ve been using an MDF top with dog holes for about 3 years and it’s worked out pretty well.

-- Trust me I'm an engineer.

View Notw's profile

Notw

471 posts in 1219 days


#8 posted 11-20-2014 03:38 PM

Might I suggest another idea, I did my bench very similar to how it sounds you are doing yours. For the apron I used 3/4 popular wood instead of the douglas fir. The top of mine is constructed from (2) layers of 3/4” plywood with a 3/4” MDF top. I opted out of the replaceable top board with the thinking that by the time I wore this top out I would want to do a beefier solid top anyway.

Back to your question though I chose to drill and countersink the screws straight though the popular apron and then accent them with walnut plugs. It not only secured my apron in place but it also made a nice design addition to the bench.

I also have 3/4” bench dog holes at 4” OC (a little too far apart) and use homemade dogs in it all the time and haven’t seen any distortion around the holes in the MDF.

Below is a link to my bench, it works great for me, I have added a set of workbench casters from rockler which I think is a must, especially if the wife is going to be parking in the garage some, its nice to be able to move it around.

Click for details

View BinghamtonEd's profile

BinghamtonEd

2281 posts in 1835 days


#9 posted 11-20-2014 03:49 PM

Nice looking bench, and I’m glad to hear the MDF is holding up well. I have a stack of rough cut cherry I was thinking about using for this, but I opted to save it for something nicer. I could go get some S2S poplar, but it’s a 25 minute drive each way in the wrong direction, slightly more expensive than the DF, I have a HD gift card, and HD is on my way home from work. I think I can get all the fasteners, lumber, to finish this with the gift card. I also think I can get the DF ripped, jointed, and planed in less than the hour plus it would take me to just get the poplar bought and home.

I plan to make homemade dogs, but I did put a 4-pack of the Kreg ones on my amazon wish list in case any of my family members are looking for Christmas ideas.

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

View Notw's profile

Notw

471 posts in 1219 days


#10 posted 11-20-2014 03:52 PM

I think the Douglas fir will work nicely, if I would have had my planer at the time I would have gone a route more similar to that. But I’m very happy with how mine came out and in the past 6-7 months it has taken a beating and is holding up better than I thought it would have.

Good luck with yours, I can’t wait to see pictures of the finished product

View waho6o9's profile

waho6o9

7176 posts in 2042 days


#11 posted 11-20-2014 03:53 PM

I’d attach the 2×12 as is and have a big ol apron to do
milling with:

Great advice above for attaching the apron.

View a1Jim's profile

a1Jim

115202 posts in 3043 days


#12 posted 11-20-2014 04:19 PM

Ed are you talking about aprons as pictured in waho609’s drawing or are you talking about banding the edge of the MDF ?
As far as the overhang ,the MDF is plenty strong for even a deeper than 3” overhang. I would not every make a bench without an overhang ,the overhang is invaluable for clamping projects down to the bench.

-- http://artisticwoodstudio.com Custom furniture

View timbertailor's profile

timbertailor

1592 posts in 890 days


#13 posted 11-20-2014 04:27 PM

Glue it.

MDF does not take kindly to any kind of screw except T Nuts.

MDF is not the best choice for a work surface. They tend to warp over time because of humidity and do not take well to fluids.

I would have suggested using birch plywood or a solid wood.

-- Brad, Texas, https://www.youtube.com/user/tonkatoytruck/feed

View BinghamtonEd's profile

BinghamtonEd

2281 posts in 1835 days


#14 posted 11-20-2014 04:29 PM

Jim, I’m not sure which terminology you would use. I will be attaching the DF to the edges of the MDF. I’m making it taller than the MDF edge so that it hangs below and I can clamp against it with an F-style clamp. I’m not making it 12” tall, though. I’m thinking more like 4”. I may drill a few dog holes in it so I can support longer boards for jointing edges without clamps, though.

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

View CharlesA's profile

CharlesA

3023 posts in 1263 days


#15 posted 11-20-2014 04:30 PM

I had two mdf panels glued together for my first workbench, and it worked quite well. Stayed flat, good surface, etc.

-- "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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