Thread: Is thick plywood too bouncy for workbench top?

Hi Tom,
Why not use form ply on top. That way you have a strong and water proof surface and best of all glue don't stick to it and it wipes over very easily and won't hold or be affected by those little spills of stain, beer and stuff?


Cheers


Steve

Originally Posted by tomnewby

I am hoping to leave the plywood showing. Its pretty dark under the house and i'm aiming to have a light colour to the top.
Tom

On my bench I used the masonite/hardboard that is white coated.
I have a vinyl off cut from the kitchen floor that over lays the hardboard for working on engine parts and other wood killers.


and now for something completely different.......

On the floor next to the bench I have some pool cover off cut (like giant bubble wrap), it is nicer than concrete to stand on.

I think 75 mm is well overkill.

I have a workbench top made of 18mm pine ply.
I have rebated out and glude a 3" x 4" hardwood front edge the rebate is the depth of the ply and about 2" wide.
the first row of dog holes go thru the back portion of the 3 x 4 edging strip.

the second row of dog holes are backed up by another strip of 2 x 3 hardwood.

there is an 18mm vertical kick panel at the rear.

there are thinner hardwood caps across the end of the bench.

There is no problem with the bench top.

remember that ply wood is at its best advantage working as a diaphram.
and
most of the thumping and banging is done at the front and ends of the bench.

So make sure the front and the ends of the bench are solid, the middle will more or less look after its self

No when you talk about hardwood ply.....excatly what timber is that....because much of the "hardwood ply" is meranti which is no harder or heavier than pine

Another issue with ply... it may be dimensionaly stable about its length and width.... but by its very nature there is stress within it that can and does make it warp.

I made up a pair of low work benches that I do most of my assembly on.

these were made by laminating out of 19mm ply.....one of them is fine but the other continues to warp diagonaly...I have flatened it twice.

So would recomend the use of good dry and stable hardwood to frame the bench and keep it straight.

As for the rest of the ply.

so many work benches are or end up wobbly, there is often insufficient racking strenght.
use the ply to brace the legs cross ways and lengthways.
adding a shelf can improve strenght.

remember that strenght of the legs is very important and keeping them as near as practical to the edges.

As for mounting your vice with lag screws ( coach bolts)...I would not.

you are better of using bolts counterbored in from the top and then covered with plugs.

On the first incarnation of my bench I made the mistake of settig the vices in from the ends.
put your vices right up flush with the edge/end.... the put your legs as close to the inside of the vices as you can.

Now to surface durability.
Id you are a butcher and are prone to drilling and cutting and gluing into the top of your bench....definitely consider a sacrificial top.
If you dont do that sort of thing pine is plenty hard enough particularly once it is given a coat of sanding sealer and wax.

If you are considering what ply...I would consider BB hoop.

cheers

Thanks for that soundman

As far as base design, I'm basing mine on a design from Sam Allen's Making Workbenches. It is a "simple joiners bench". the attached link is to a google booksearch preview of it. You can see a photo of the bench on page 15. The base is held to together with truss rods which can be tightened down the track if required. The plan in the book (but not shown in the preview) builds a top out of three sheets of laminated particleboard with a masonite/hardboard skin on the top and edges.

He does say however that it can be done with ply if you'd prefer a more traditional wood finish. So this is what I'm contemplating.

On page 16 you can see how the vice is positioned. Like you said, close to the end and up against the leg. On page 19 are his instructions on fitting the vice, bolts counter sunk but then covered by last sheet.

I'm going to subsituting the Veritas twin screw with a large front vice that takes a full wood jaw. I now the single screw ones can wrack but I'll make up some stop blocks, and save myself a couple of hundred dollars.

http://books.google.com.au/books?id=...esult#PPA15,M1

I'm not sure what wood is used in the hardwood plywood. I'm going out to Gunnersens on Saturday morning to have a look. On their website it suggests there are various types. So I'll see what they have got.

Thanks for input.
Tom

Instead of a 3rd layer of ply to cover bolts, on my old bench I recessed them into the top, then cut and glued timber plugs into the recessed holes over the bolts, and planed them flush. Worked fine.

regards

One big problem with ply is that it is edge fragile, it is easy to pull big chunks out of the egde of ply, same with MDF and chipboard.
this is another good reason to run on a substanmtial hardwood edge.

remember in structrula physics weight does not always equal strenght or deadness.
Ply although lighter is considerably stronger than both MDF and chipboard.

One ver good reason not to use formply and to a lesser extent tempered masonite is they both take the edge off tools.
The coating on formply is melamine which is hard and abrasive.

the reason we make our benches out of wood is so we dont bu#### our tools.

when I was an apprentice all our benches were topped with varnished tempered masonite...they were great .. but it wasn;t a wood work shop.

I have coated all my bench tops with a generous thinned coat of pulyeurathane sanding sealer ( sanded ) and then wax over that.

it is fine....when it get scruffy I have at it with the random orbit sander and wax again.....it works great.
as long as you keep up the wax glue does not stick ( most times).

cheers

I hope this does not sound too sooky but what a great forum is this!

So much knowledge and experience shared generously, willingly and courteously from men and women.

A cove comes on asking a good question. On many fora he would receive at least a few smart-???? replies, questioning his manliness etc. Not here, just help.

I am too old now for fighting, ugliness, unpleasantness and I compliment all here for your teaching and good will.

Thank you.

I wholeheartedly concur old farmer!

Soundman, I had that exact concern about edge fragilty. I have decided I will edge it in hardwood. Well at least the front strip. I plan to use it as the jaw liner for the rear vice... two birds one stone. The tail vice needs one also so i'll make them matching.

And thanks for the finishing tips.

Thanks
Tom

I followed that link to Sam Allen's "Making Workbenches' book and found that the illustration 2.7 is exactly how I mounted my Record vise - I wish I'd known about that illustration earlier, it would have saved me a lot of time in planning!

The top of my 'buried' rear vise jaw is exactly 40mm below the top of the bench (38mm + 2mm gap to allow for seasonal or other movement). I could have mounted it higher, by cutting a recess in the 38mm door that forms the top layer of the bench (as Sam Allen does), but this would have raised the height of the guide rods and therefore reduced the capacity of the vise.

You've asked whether having the top of the metal vise jaws 25mm below the level of benchtop is too much. I used tassie oak for the wooden front and rear jaws, although its not that stiff a timber, the play in the wooden jaws over that 40mm is undetectable - they still pinch tight along the top edge. If the gap opens over time, its likely to be the front jaw that is wearing or moving, given that its relatively unsupported compared to the rear jaw, and so its a simple job to replace it. However as the rear jaw can't be easily replaced, you'd have probably have to insert a strip of wood to repair any damage to it.

when I get some time I'm planning on lining the front jaw with leather, to increase its grip - the oiled tassie oak is a bit slippery for my liking.

My last bench has a solid jarrah and treated pine frame like this;


And a drop-in 19 mm plywood top held in by Z-clips like this.


The drop in design protects the edges. Right now its dinged and filthy, I'll sand it down a couple more times and when it's too far gone I'll just replace the top.

Both faces on both vices are leather lined - one of the best things I ever did.

consider that a portable stage that I sometimes use, supports a 1200 x 2400 sheet of 18 or 19mm structrual ply arround the edge with a brace across the middle and supported on 6 legs.... this stage is rated to support centre panel point loadings sufficient to park cars on it.

and 18 or 19mm structrual ply is used as a flooring surface in both domestic and commecial buildings with quite wide stud spacings.

there is sufficient strenght in one thickness as long as you beef up the edges.

remember also that each and every dog hole represents an edge... and play is somewhat edge fragile.
That is why I backed my dog holes with a decent thickness of hardwood...so the racking of the dogs is more taken in the hardwood.

one thickness of 25mm would be much more than plenty.

if you realy want to go looney... see if you can get onto some plywood bridge planking, which from memory is 45mm thick but only comes about 250mm wide... it gets used for stairs or scafold planks sometimes too.


just some thaughts.

cheers

Hi Soundman

On the strength issue... I'm not using 75mm to gain more strength, its to negate the flex and bounce. You did this by adding a solid wooden strip along the front.

I'm hoping the weight of the three thick layers renders it "dead" and to not bounce or flex when using a mallet on a chisel, or other such techniques. I'm hoping I can achieve this without having to add solid wood fronts and avoid added joinery and construction time. I guess thats the essence of why I'm planning on 75mm. Ease of construction, and no bounce or flex, while maintaining a lighter coloured top.

Cheers
Tom

BobL. That is a solid looking beast!

bounce, flex......strenght........how do you seperate these.

laminating up three layers of ply.. to me is more of a pain that running a few strips ( heavy though they may be) of hardwood down the sides and middle

all the joinery if you call it that can be done on the table saw or with a hand circular saw.

how are you going to get sufficient clamping preasure to get a good bond over the full surface area... and how are you going to get that clamping preasure even so the whole thing stays flat and straight.

then if 75mm of ply decides it is going to warp..... what do you stop it with?

cheers