Making a New WorkBench

[Marc Prudhomme]

Hello gentleman,
After my last failed attempt at an inexpensive workbench I am ready to try again.This time I will be using 3 layers of 3/4 MDF with a hardboard top(Replacable.)I am using glue and screws for the lamination.I do plan on removing the screws and drilling or boring holes for dogs.Has anyone had any experience with dog holes in MDF?will it hold up? I am also thinking about just screwing down the hardboard so it can be easily replaced.
Lets here any thoughts.
Marc

[Rich Engelhardt]

Hello,

Has anyone had any experience with dog holes in MDF?will it hold up?
Yes.
No.
MDF get's "crumbly" around the edges. More crumble = more pressure on the dogs. More pressure = more crumble.,,etc,etc.

[Jim Becker]

Although what Rich says is true about MDF, unless you are a heavy bench user, I doubt very much that you are going to have a problem with your dog holes, especially with that thickness of lamination. There is a lot more support for the actual dog, so it will be less likely to damage the edges of the hole. Three layers is also going to give you some wonderful mass...a nice heavy bench. Be sure to design and build a base that is commensurate with that mass and weight!

I wouldn't screw down the hard board...if you make your aprons such that they are exposed the exact same height as the hardboard over the MDF subsurface and carefully size it, it's not going anywhere. Totally captive. Just clamp it down as you drill your dog holes for best results. When it comes time to replace it, that top becomes the template for the new one.

[Marc Prudhomme]

I agree Jim.I am kind of a novice and I really dont have as much time as I would like for the hobby.I do not think I will over using my dogs or overstressing.Worst case ,I figure I could always put a bushing in if it wears out,but I dont think I will need to do that.

Just a thought,should I use a piece of 3/4 plywood on top for my third layer instead of MDF.Would that help?
Although what Rich says is true about MDF, unless you are a heavy bench user, I doubt very much that you are going to have a problem with your dog holes, especially with that thickness of lamination. There is a lot more support for the actual dog, so it will be less likely to damage the edges of the hole. Three layers is also going to give you some wonderful mass...a nice heavy bench. Be sure to design and build a base that is commensurate with that mass and weight!

I wouldn't screw down the hard board...if you make your aprons such that they are exposed the exact same height as the hardboard over the MDF subsurface and carefully size it, it's not going anywhere. Totally captive. Just clamp it down as you drill your dog holes for best results. When it comes time to replace it, that top becomes the template for the new one.

[Lee Koepke]

I read about someone that used cut outs in the MDF for hardwood where the dog holes were going. maybe if you did that in the top/middle layer that could give better support?

[Jim Becker]

Just a thought,should I use a piece of 3/4 plywood on top for my third layer instead of MDF.Would that help?

I wouldn't. You lose some of the mass and don't really get much for it. And plywood is a lot more expensive than MDF...and usually less flat.

What Lee describes is something important to consider relative to vice mounting. Embedding some hardwood like oak will give you something for the bolts to have purchase in as you mount your vices. Of course, you'll want those vices in-hand so you can plan for their location and the appropriate spots for the reinforcement. I'd use the hardwood for that, too, rather than plywood because MDF is a true 3/4" thick and plywood generally isn't. You can thickness hardwood to the exact same dimension as the MDF before inlaying it in your middle layer.

[Sue Wise]

I built Sam Allen's Joiners bench about 10 years ago. (I love this bench.) It has 3 layers of particle board with top layer of hardboard. I used nails to hold the layers together for glue drying. The idea is you lay out the nails in a grid and then drill the dog holes where there are not nails. I only drilled a couple of rows of dog holes. His plan has the entire table drilled with them just like a MFT.

I only use a shoulder vise and decided to bolt it on through the base instead of using screws or lag bolts, so I can take it off and put it together again when I needed to move it to a different shop. The base uses metal truss rods for stability and joinery. The wood for the base is 2x4's and 4x4's. The base can be taken apart and put together again time afer time with no problems. Just tighten up the rods and it isn't moving an inch.

This bench is heavy and sturdy. It is found in Sam Allen's, Making Workbenches book. Not pretty but it is a great bench. You can pound on that thing all day with no worries.

[glenn bradley]

My top is 4 layers of MDF. No problems with the dog holes. Your holding wood, not working on a car. If your dogs fit well you would have to really lay into it to crush the edges. If your dogs are sloppy, you will have issues. I treated my top with liberal amounts of BLO. Maybe this has made it more resilient(?) or maybe my hobbiest level of use is just not enough to cause an issue.

[Sue Wise]

Glen, if that is 4 layers of 3/4 MDF it will hold a car. :)

[Brian Dormer]

I wonder if square .vs. round dog holes would make any difference? (prepares for massive onslaught from both camps)

From a theoretical perspective, I would think that ROUND holes would have less stress points (ie. corners) for cracks to start in. Maybe also consider chamfering the bottoms of the holes (tops should be fine, because the hardboard will take the beating.

(thinking for a few seconds....) MAYBE even better - sandwich the MDF between hardboard (top AND bottom) so the hardboard protects the crumbly MDF edges from wearing under the dogs. The bottom hardboard can be glued in - let the top "float" as Jim suggests.

my 2 cents....

bd

[Randal Stevenson]

I wonder if square .vs. round dog holes would make any difference? (prepares for massive onslaught from both camps)

From a theoretical perspective, I would think that ROUND holes would have less stress points (ie. corners) for cracks to start in. Maybe also consider chamfering the bottoms of the holes (tops should be fine, because the hardboard will take the beating.

(thinking for a few seconds....) MAYBE even better - sandwich the MDF between hardboard (top AND bottom) so the hardboard protects the crumbly MDF edges from wearing under the dogs. The bottom hardboard can be glued in - let the top "float" as Jim suggests.

my 2 cents....

bd

Combine the two types of dogs. Use a round dog, with instead of a flat side, a square block over the peg. This should spread any "weight" over the surface better.

[Marc Prudhomme]

Glenn.,Got any pictures???
My top is 4 layers of MDF. No problems with the dog holes. Your holding wood, not working on a car. If your dogs fit well you would have to really lay into it to crush the edges. If your dogs are sloppy, you will have issues. I treated my top with liberal amounts of BLO. Maybe this has made it more resilient(?) or maybe my hobbiest level of use is just not enough to cause an issue.

[Wilbur Pan]

Just curious -- why not laminate a bunch of 2x4's for your workbench top? 2x4's are cheap.

[Todd Jensen]

2x4s are cheap but not as flat from the 'factory' as mdf sheets. I love my 2x4 lam workbenches for most stuff but wouldn't use them for my central work table. JMO.
After you drill your dog holes I would coat them with Wood Hardener for a little extra insurance and you should be fine as stated above for all intents and purposes. I'm assuming you're just using them to hold your workpiece while you sand, rout, or handplane, etc. and not to clamp together an 8/4 Jatoba tabletop.
Have fun with your project!

[Jim Becker]

Just curious -- why not laminate a bunch of 2x4's for your workbench top? 2x4's are cheap.

In addition to Todd's comments, 2x4s also have very little mass as compared to 3 layers of MDF. Mass is desirable in a workbench, especially one that will be used with hand-tools.

[Carroll Courtney]

I made mine out of 3/4MDF torson box style.Where I mounted my vise and the holes for the bench dog,I fill the void areas with more mdf.Glued everthing.Its heavy,flat,square.

[Wilbur Pan]

In addition to Todd's comments, 2x4s also have very little mass as compared to 3 layers of MDF. Mass is desirable in a workbench, especially one that will be used with hand-tools.

The density of Douglas fir or Southern yellow pine, which seems to be the more common woods that 2x material is made of, is about 500-550 kg/m3. The density of MDF is 600-700 kg/m3. This does make MDF more dense than 2x material, but I'm not sure I would characterize it as "very little mass".

In addition, a 2x4 turned on its side should give you a top that is on the order of 3 1/4 inches thick, accounting for thickness lost by planing the surface smooth. Three sheets of 3/4" MDF is 2 1/4" thick. The mass of 3 1/4" of wood that is 500 kg/m3 is pretty close to a 2 1/4" of material that is 700 kg/m3 thick, if I've done my math right.

For what it's worth, my workbench is being made with 2x material. I figure the weight difference is negligible, based on the calculations above, I like the look better than MDF, and since my bench is going to be a hand tool bench, I figure there's nothing better to get my planing techinque up to snuff than leveling a workbench top. ;)

But either 2x material or MDF will give you a very serviceable workbench.

Of course, Marc could also go with 4 sheets of MDF. ;)

[Bart Leetch]

The density of Douglas fir or Southern yellow pine, which seems to be the more common woods that 2x material is made of, is about 500-550 kg/m3. The density of MDF is 600-700 kg/m3. This does make MDF more dense than 2x material, but I'm not sure I would characterize it as "very little mass".

In addition, a 2x4 turned on its side should give you a top that is on the order of 3 1/4 inches thick, accounting for thickness lost by planing the surface smooth. Three sheets of 3/4" MDF is 2 1/4" thick. The mass of 3 1/4" of wood that is 500 kg/m3 is pretty close to a 2 1/4" of material that is 700 kg/m3 thick, if I've done my math right.

For what it's worth, my workbench is being made with 2x material. I figure the weight difference is negligible, based on the calculations above, I like the look better than MDF, and since my bench is going to be a hand tool bench, I figure there's nothing better to get my planing techinque up to snuff than leveling a workbench top. ;)

But either 2x material or MDF will give you a very serviceable workbench.

Of course, Marc could also go with 4 sheets of MDF. ;)

Well I like the wood myself BUT I like the laminated up sheet goods or torsion box better because I can put a replaceable tempered Masonite top on the bench.

My bench is made of 1" plywood for the base sheet on top of that is a 3/4" high density sheet of chip board & then piece of 1/4" tempered Masonite all banded with Poplar. The only material I purchased for this bench was the chip board & Masonite.

[Doug Shepard]

Is there anything to be gained by lightly chamfering the dog hole edges? I'm not too far off from putting dog holes in a BB ply benchtop where the top layer is laminated edge-side up. I've been wondering about putting a 1/32 or 1/16" chamfer on the hole to stop any chipping of veneer layers.
?????

[Todd Jensen]

Doug, I would blue tape over your hole locations before drilling being sure the surface is clean and you've got good adhesion to prevent chipout while drilling. After that, a slight chamfer and (okay, so I like wood hardener)some of that, and you should be good to go. I think the chamfer is a great idea.

[Bill Wyko]

Have you considered building a torsion table of sort?

[Marc Prudhomme]

Yes I have but i am looking for some weight oon this table because I will be mounting heavy duty wheels for mobility.The weight will help keep it a little more stable with the wheels locked.

Have you considered building a torsion table of sort?