Workbench top thickness. Is 35mm too thin

[SMALMALEKI]

I am enjoying the process of building my workbench. It has been an amazing journey so far. I have practiced diffeeent skills from cutting to planning by hand and laminating.
I decided to built an ultimate vice for my bench. A twin screw chain driven vice almost 900 mm long. I doubt there would have been better project to learn on the job than this bench.

Now I am installing the vice to bench. I have to attach two standoffs to underneath my workbench top.
As you can see from the drawings I have to carve out a hole 2.5 inch deep. It leaves only 35 mm thickness for my workbench top. If I fix the standoffs directly to underneath of bench then my vice jaw will be about 20 mm lower than workbench top.

Shall I keep my workbench top as it is and later add a strip of 20 mm to the vice jaw to level it with the top?

I hope you get the picture.

 

[MikeG.]

Not at all. Most old benches were less, and you are only proposing to have it 35mm locally to the vice. Mine's less than that over the entirety of the top.

 

[worn thumbs]

The answer to your question is that 35mm is more than adequate.I have used several benches that had tops made from 18mm MDF-not great but they worked.A bit of framing beneath the bench is worth quite a lot.We tended to lay a sheet of hardboard on them to take the knocks and scratches.

I might find it enlightening to know what features you seek on an "ultimate" bench. I do hope you haven't been taking too much notice of some of the American alleged experts as their benches look very old fashioned.We were fortunate enough to have Record quick release vices and they are very hard to beat for workholding.A heavy bench is good but for strength try not to use halving joints everywhere as you instantly cut away half the strength of the components.

 

[SMALMALEKI]

My bench is based on Mr Paul Sellers English workbench with two skirts adding to the strength of the frame. I liked the twin screw chain driven vice design and made one at home with help from a friend. I have found problem with all twin screw vice designs and it has been a good learning point. The most important drawback of the system is relying on screws to move the jaw and take the weight of it at the same time. Almost all of them have a sagging of the vice jaw to some degree.

 

[Phil Pascoe]

I think the jaws are always better lower with a wooden cover strip - they save your tools getting damaged on the steel.

 

[AJB Temple]

My view for what it is worth. What you want from a bench is rigidity and stability. Solid legs. Low centre of gravity. Plenty of weight to it (even if you use concrete breeze blocks mounted low down).

As long as the top doesn't flex, your'e good to go.

 

[woodbloke66]

My view for what it is worth. What you want from a bench is rigidity and stability. Solid legs. Low centre of gravity. Plenty of weight to it (even if you use concrete breeze blocks mounted low down).

As long as the top doesn't flex, your'e good to go.

Agreed.

A 35mm top is adequate and ought to allow you to most stuff; what it won't do is to add weight to the overall design and that's one of the most important features of any self-respecting bench. Schwarz mentions in the ATC that once a bench gets to around 130Kgs it's not going anywhere, no matter what you do on it or to it. To add rigidity and prevent the frame from 'racking' a diagonal bracer can be added at the back, or even glue and screw on a large bit of half-inch ply; it doesn't matter too much. A good way to make a really solid, heavy dense top is to use a triple laminated layer of 18 or 22mm mdf, over which you can pin a sacrificial layer of exterior hardboard.
Lots of different options can be used in bench building depending on budget, but simple usually works - Rob

 

[Jacob]

The classic British bench (as seen everywhere when the trade was big industry) had very thick tops - typically one or two 9" x 3" pieces of beech. The reason is inertia and resistance when heavy hammering going on such as morticing by hand.
I really notice the lack on my bench (3x 9 " redwood) - the most inert and deadest bit is over the legs.
I tried at first with sacrificial layer of 3/4" birch ply but years later discovered it was better without. Layers introduce bounce!

 

[woodbloke66]

Layers introduce bounce!

Jacob, I should have mentioned that Paul Chapman, who used to post regularly here, had a triple laminated mdf top on his bench, but he glued/screwed them all together...no bounce! I used his bench a couple of times a few years ago and it was a rock solid as solid thing - Rob

 

[MusicMan]

That thickness will be fine above the pockets for the vice. You have much mass elsewhere.

Would you like to share your twin-screw design?

 

[SMALMALEKI]

Hi
It is based on LN design and I made the dimensions myself. I bought the ACME screws and all hardwares from overseas while on holiday. I have posted about it on the forum.
post1249838.html#p1249838

 

[Jacob]

Layers introduce bounce!

Jacob, I should have mentioned that Paul Chapman, who used to post regularly here, had a triple laminated mdf top on his bench, but he glued/screwed them all together...no bounce! I used his bench a couple of times a few years ago and it was a rock solid as solid thing - Rob

If it's solid like one piece of ply it should be good.
I was thinking of "sacrificial"layers which by definition have to be loosely attached.
What's happened to Paul? I remember him well, met him a couple of times.

 

[woodbloke66]

What's happened to Paul? I remember him well, met him a couple of times.

Haven't seen Paul for a number of years now and I assume he's still keeping well. I did notice the other day that he's started to post on Instagram, so I guess he's fine, but I've really lost contact with him, which is a shame - Rob

 

[MusicMan]

Hi
It is based on LN design and I made the dimensions myself. I bought the ACME screws and all hardwares from overseas while on holiday. I have posted about it on the forum.
post1249838.html#p1249838

Thanks. Looking forward to seeing it installed and working!

 

[autotrans]

plenty of support and it will be good

 

[Simon_M]

even glue and screw on a large bit of half-inch ply

Good advice. I modified a “commercial” workbench with half-inch ply across the rear legs, stiffened at the top with the worktop. Midway there is an additional half-inch ply shelf over the two stretchers and the ply back is further braced at the bottom and there is an additional third stretcher. The centre section of the worktop is minimally “ only” 50mm thick as the 100mm aprons mask this, even so the majority of the weight is in the top and it seems altogether very rigid. Some of the joints were pulled together with additional bolts copied from the leg/stretchers.

 

[SammyQ]

"Layers introduce bounce!"

Loose layers might...though I don't know how...Jacob on a stirring crusade again??? Glued or screwed ones certainly do not.

Sam, whose laminated one, glue only, is not only stable, but hernia-inducing; no way a bit of work is moving it.