diy workbench stability issues

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33coupe

667 posts

Ultimate Geek

# 162009 26-Jan-2015 19:50

I'm a real novice when it comes to this kind of thing so any help would be greatly appreciated.

I'm attempting to build a workbench /cabinet to keep tools in etc.

So far I have used 2 doors for a top and bottom, and 4 pieces of solid timber as the posts inbetween at the corners.

The trouble I have is that there is a slight wobble / movement (as I expected) from side to side.

Im trying to think of the best /easiest solution to the problem.

I was thinking either:

1) buy a piece of plywood big enough to cover the back

2) one or two pieces of wood and screw between the posts at the corners

Would either work, or do i need to do something else?

Thanks

PS As it's pretty rubbish, I'd rather not spend too much money on it

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# 1222698 26-Jan-2015 19:55

Yeah panel on the back should help stiffen it right up, might as well add ones to each side too. I'd go with MDF as it's cheaper than ply (doesn't need to look good or be durable, just hold) and you can often get seconds from the hardware store

Also doesn't need to cover the full height, my workbench is around 900mm high, and the back brace only goes down 400mm or so from the top. The bench is solid as

33coupe

667 posts

Ultimate Geek

# 1222705 26-Jan-2015 20:19

Thanks for the quick reply.

That's good to know, I'll keep an eye out for some cheap mdf.

I was also wondering if i could use the remaining 3 doors i picked up for free to make a tv / entertainment cabinet?
They might not be solid wood, but i thought with enough support posts, it would hold a tv ok.

nickb800

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# 1222712 26-Jan-2015 20:45

You could, but the tricky bit is when you go to cut them and you get an open end - which is both ugly and weak. The solid frame typically only goes around the outside so if you cut a door, say in half, then you'll need a good connection between the outside frame of the door and whatever support posts you have. It'd be a bit like surgery, and a good chance of failure. Personally i wouldn't bother if the doors are hollow.

Keep an eye on trademe for MDF or ply, many places sell cover sheets, which have a slight blemish on one size, and usually quite cheap

33coupe

667 posts

Ultimate Geek

# 1222722 26-Jan-2015 20:55

Sorry i should have said i wasn't going to cut them. So it would be big, but should have retain a bit of strength.
Just an idea at this stage, and i think i need to work on my carpentry skills before i start buying any wood etc.

Thanks for the info

SepticSceptic

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# 1223406 27-Jan-2015 17:30

Brace it - A length of 50mm wide, 10 or so thick timber, from say 1/3rd up from the bottom of one back leg, then attached along the back edge of the table, equivalent to the 2/3rds the length of the leg, from where the leg joins the table. Basically making a triangle. The longer you can make the sides of the triangle, the less wobble it would have. Bracing one leg will be enough, but bracing both back legs would be better.

My thoughts are no longer my own and is probably representative of our media-controlled government

mcraenz

1091 posts

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# 1224082 28-Jan-2015 14:31

I would suggest ply for bracing not MDF. It's lighter and stronger. Even a 6mm ply will give you a huge amount of rigidity especially if you can put it in a frame/torsion box arrangement.

This is how I build my benches (aka earthquake shelters):
http://blog.rhysgoodwin.com/home-diy/workshop-and-workbench-update/

http://blog.rhysgoodwin.com/home-diy/milling-machine-bench-and-workshop-update/

Visit My Blog!

33coupe

667 posts

Ultimate Geek

# 1224400 28-Jan-2015 22:32

Thanks for the replies/ info.

I might try the sheet of ply or MDF as it looks easier than the brace technique.

Mcraenz, that is a whole new level, amazing work.

TLD

700 posts

Ultimate Geek

# 1224410 28-Jan-2015 22:49

Triangulation. Think iron bridges, or those wooden rail bridges from old cowboy films. This shows how it works and why. A brace in tension works better than one in compression — for a given cross sectional area. So you tend to see multiple braces at 90° to each other, so either one will be in tension depending on which way the structure is trying to deflect. A flat panel fixed to the back makes an excellent brace.

Trevor Dennis
Rapaura (near Blenheim)

33coupe

667 posts

Ultimate Geek

# 1245934 24-Feb-2015 21:22

Sorry to bring this back up.

I am finally getting close to finishing this.

Can someone confirm that a piece of MDF 3mm thick would do the trick? I've found a sheet for $5 which seems cheap.

Thanks

mcraenz

1091 posts

Uber Geek

# 1245947 24-Feb-2015 21:33

2 people support this post

3mm is way to thin for mdf. For ply I'd go 9mm minimum. Mdf I'd go 12mm minimum. Ply would be much better in my opinion.

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33coupe

667 posts

Ultimate Geek

# 1245987 24-Feb-2015 22:25

Thanks for the reply. Oh really, I didn't know that.

As its just the back and sides, and goes from corner to corner, I thought any size would do the job.

I'll keep an eye out for a thicker piece.

mcraenz

1091 posts

Uber Geek

# 1245992 24-Feb-2015 22:35

MDF especially really thin stuff tends to absorb moisture and can go soft. Think of it as very dense cardboard. Wood on the other hand consists of long strands and is made of multiple layers with the grain (strands) running in opposite directions. This makes it extremely rigid for bracing.

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33coupe

667 posts

Ultimate Geek

# 1246628 25-Feb-2015 18:46

That's a good point about mdf.

As I want it to last a long time I will go with ply.

If anyone knows of cheap ply please let me know.

That's

TwoSeven

1382 posts

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# 1246652 25-Feb-2015 19:45

My bench is similar to the one in the picture above - except I made it an L-shape to fit in a corner. What I did was to build two levels - the top of the bench and the same again but 3/4 of the way down so I had a shelf. For each surface I used particle board, however for the top layer I also had some stainless folded for me (the back is folded up 4" to give a splashback, and the front and sides are folded down to cover the 4x2 timber frames).

The bottom layer effectively adds horizontal cross bracing (and I think from memory at the back I used diagonal bracing as per the above diagram).

The only thing I forgot to do when I made it is factor in where I would put my two metal working vices and the woodworking one.

Software Engineer

Hatch

539 posts

Ultimate Geek

# 1247599 27-Feb-2015 10:17

mcraenz: I would suggest ply for bracing not MDF. It's lighter and stronger. Even a 6mm ply will give you a huge amount of rigidity especially if you can put it in a frame/torsion box arrangement.

This is how I build my benches (aka earthquake shelters):
http://blog.rhysgoodwin.com/home-diy/workshop-and-workbench-update/

http://blog.rhysgoodwin.com/home-diy/milling-machine-bench-and-workshop-update/

This is epic, many thanks!

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