Bench Tops

[marcros]

I am about to embark on a bench build, using the Scwarz English workbench as a guide. I am pretty happy with my plans so far but I am thinking about the bench top itself. I am aiming for a thickness of IRO 65mm to make optimal use of holdfasts, but have probably =/- 10mm where they will still work well.

As a base, I have a 44mm thick solid core firedoor. Dense, flat and cheap. My plan is to add a layer of something to this. Would 18mm ply, mdf or the green chipboard flooring be most suited? How is one fixed to the other to maintain flatness? Am I right to be concerned that the board will be subjected to different conditions top and bottom which could induce warping, or should a solid bond to the firedoor prevent this?

Next, I was planning a sacraficial top layer. Would hardboard or thin ply be better for this? If hardboard, oli tempered, normal or white faced? I saw a thread from Derek Cohen where he commented on having a dark coloured bench as not being ideal (although to be fair if I could produce something half as good as he has on this bench I would be over the moon!). Again, how do I fix this so that it can be removed if required and has no metal in it that could damage edges?

What if any finish should be applied to this top?

Thanks
Mark

 

[marcros]

anybody?

 

[Rob Platt]

personally i`ve never used a sacrificial top in my life not familiar with the bench design via its name/book. if i was using a door as a top and it was 30" i`d cut 6" off and make a front apron, beefy legs near to the vices for max support and if you need greater than 44mm for the holdfasts to work i`d put cls or something similar underneath keeping my door on top or not bother with the holdfasts.
all the best
rob

 

[dedee]

Mark, here is a link to a bench I built earlier in the year.

http://thewoodhaven.co.uk/phpBB3/viewto ... nch#p20714

The top was made from a 25mm chipboard desk top and 3 layers of 18mm MDF only the top layer was MRMDF. Each sheet of MDF was lipped with beech to protect the edges. The 3 sheets of MDF were glued together and remained very flat. The steel rulers in one of the images are standing on edge. The chipboard sub base is attached to the leg frames and back. The MDF was then plonked on top and screwed from the chipboard side. NB make sure the screws will not interfere with dog hole placements

I do not see the need for sacrificial top at the moment although I could add one later if necessary.

Hope this helps


Andy

 

[marcros]

Thanks Andy, that helps a lot.

 

[Paul Chapman]

Mine's similar to Andy's - 3 layers of lipped 18mm MDF. Built about 12 years ago and still OK

Recently modified it to fit the Veritas quick-release tail vice and twin-screw front vice

MDF stands up well to wear and tear in my experience and stays flat. I just wax the top of mine occasionally. No need for sacrificial tops.

Hope this helps.

Cheers :wink:

Paul

 

[marcros]

Are the layers just glued together Paul, or glued and screwed?

 

[bosshogg]

Hi Mark, can you tell us what the bench is mostly to be used for, planing, chiselling, assembly?
If for instance you use your bench for hand planing and chopping lots of mortices, even if a lot of what you do is achieved with power tools on the bench, then you'll probably want something like 75mm thick, especially if you use bench holdfasts, which use the thickness of the top to brace against, providing the perpendicular restraining force that gives the horizontal holdfast arm it's strength. A thinner top (44mm softwood solid core door) would be more likely to wear if these were used constantly.
Now if the bench is more used for assembling projects, then a solid core fire door would be sufficient, in fact that is what I have and use quite successfully, but then again I don't use holdfasts...with all of this in mind you can consider what you really require, and how often it will be used.

Hope this helps...bosshogg

P.S. for similar reasoning, I would tend to agree that a sacraficial top would probably not be a good idea :idea:

I never teach my pupils. I only attempt to provide the conditions in which they can learn.
Albert Einstein 8)

 

[Paul Chapman]

Are the layers just glued together Paul, or glued and screwed?

I lipped the individual sheets first, with glue and biscuits. Planed the lippings flush then glued the three sheets together, with a couple of biscuits for location.

The main problem when gluing is to maintain even clamping pressure over the whole surface. I used lots of G cramps and curved wooden cauls. By using the curved cauls, you can do up the cramps at the sides of the top and the cauls put pressure on the centre. You only need a slight curve in them.

If you go ahead with it, get someone to help you - 3 layers of MDF weigh a lot :shock:

Cheers :wink:

Paul

PS Just a thought - if you didn't have enough G cramps, you could use glue and screws from underneath. After the glue is set, you could either leave the screws in or take them out.

 

[dedee]

Mine's similar to Andy's - 3 layers of lipped 18mm MDF.

I should hope so as mine was a copy (interpretation) of yours.

Cheers

Andy

 

[marcros]

Bosshog,

It is going to be an everything bench used for a multitude of things, including chopping some mortices and dovetails, a bit of handplaning and some assembly. That said, I am only a hobbyist, with time constraints, so it is not going to see hours and hours of use each week- wearing quickly is relative. I may well make an assembly table in due course, but for the moment this bench will have to do everything.

To put it into perspective, I have a planer, a benchtop thicknesser and a table saw which I would use to dimension stock. I am in the process of finishing a router table, and I have a pillar drill which is going to be on a stand alone base. Handplaning is likely to be on the edges of boards- thicknessing by hand is not something that I am that keen on doing! Chiselling covers many things, but it is the kerf cut dovetails that I like to see, so I am thinking jewellery boxes and similar scale for chiselling operations. I did buy a Leigh jig 12 months ago, and although I am yet to use it, would do so to do things like drawers (at this stage in my woodworking "career?????"

Projects on my list at present (for the next couple of years) are:

Beehives- mainly assembly because the machines and powertools will do most of the rest.
Jewellery boxes- some with dovetails
Rocking Horse (possibly), but that is mainly carving and assembly
Wendyhouse- the router will be my friend! It is probably more decoration of plywood and assembly than anything.
Bed- I would use the router or a forstner bit to chop the waste out of the mortices and the bench on which to finish them off.
Other furniture- in time!

I am very keen to use holdfasts, even if I only do so from time to time. They will be useful to support long boards against the front apron, so I am going to buy a pair for that purpose. Increasing the top thickness is no problem until I cut the legs to size because the pront lamination of the leg picks up the apron, the top of which is flush with the top. I believe from Richard that the holdfasts are most effective on tops between 65 and 75mm, although if the top is thicker than that, you need to counterbore the underside. It is knowing what to buy a sheet of to add to the door (which I already have) to make the thickness in this range. I suppose, at the end of the day if the top were to wear, then at worst it is a new door and a new sheet of whatever- £50/£60 quid, which should be a couple to a few years down the line. I want a nice bench that I can be proud of, but I also dont want to spend a fortune whilst I learn what features I actually like and need in a bench having explored the frustrations of an existing one.

Thank you for your assistance- it is encouraging me to actually think about what I plan to build.

 

[marcros]

Are the layers just glued together Paul, or glued and screwed?

I lipped the individual sheets first, with glue and biscuits. Planed the lippings flush then glued the three sheets together, with a couple of biscuits for location.

The main problem when gluing is to maintain even clamping pressure over the whole surface. I used lots of G cramps and curved wooden cauls. By using the curved cauls, you can do up the cramps at the sides of the top and the cauls put pressure on the centre. You only need a slight curve in them.

If you go ahead with it, get someone to help you - 3 layers of MDF weigh a lot :shock:

Cheers :wink:

Paul

PS Just a thought - if you didn't have enough G cramps, you could use glue and screws from underneath. After the glue is set, you could either leave the screws in or take them out.

I dont have an extensive range of g clamps- 1 at last count! And I am not quite sure where that is.

I was wondering about miller dowels actually, but screws that are later removed would work.

Cauls- do you just make them? I had not came across them before, but a quick google showed something that looked like b and q pse that pushes down the middle as you clamp the ends- almost the opposite of a spring joint on 2 boards?

 

[Paul Chapman]

Cauls- do you just make them?

Yes - they are very simple. 2"x2" softwood would do. Just plane them into a very slight curve (if you buy your wood at B&Q it might be curved already :lol: ). As you apply the cramps to each end and do them up, it forces the cauls flat, thereby applying pressure to the centre. A very simple idea that really works.

Cheers :wink:

Paul

 

[bosshogg]

Bosshog,

It is going to be an everything bench used for a multitude of things, including chopping some mortices and dovetails, a bit of handplaning and some assembly. That said, I am only a hobbyist, with time constraints, so it is not going to see hours and hours of use each week- wearing quickly is relative. I may well make an assembly table in due course, but for the moment this bench will have to do everything.

To put it into perspective, I have a planer, a benchtop thicknesser and a table saw which I would use to dimension stock. I am in the process of finishing a router table, and I have a pillar drill which is going to be on a stand alone base. Handplaning is likely to be on the edges of boards- thicknessing by hand is not something that I am that keen on doing! Chiselling covers many things, but it is the kerf cut dovetails that I like to see, so I am thinking jewellery boxes and similar scale for chiselling operations. I did buy a Leigh jig 12 months ago, and although I am yet to use it, would do so to do things like drawers (at this stage in my woodworking "career?????"

Projects on my list at present (for the next couple of years) are:

Beehives- mainly assembly because the machines and powertools will do most of the rest.
Jewellery boxes- some with dovetails
Rocking Horse (possibly), but that is mainly carving and assembly
Wendyhouse- the router will be my friend! It is probably more decoration of plywood and assembly than anything.
Bed- I would use the router or a forstner bit to chop the waste out of the mortices and the bench on which to finish them off.
Other furniture- in time!

I am very keen to use holdfasts, even if I only do so from time to time. They will be useful to support long boards against the front apron, so I am going to buy a pair for that purpose. Increasing the top thickness is no problem until I cut the legs to size because the pront lamination of the leg picks up the apron, the top of which is flush with the top. I believe from Richard that the holdfasts are most effective on tops between 65 and 75mm, although if the top is thicker than that, you need to counterbore the underside. It is knowing what to buy a sheet of to add to the door (which I already have) to make the thickness in this range. I suppose, at the end of the day if the top were to wear, then at worst it is a new door and a new sheet of whatever- £50/£60 quid, which should be a couple to a few years down the line. I want a nice bench that I can be proud of, but I also dont want to spend a fortune whilst I learn what features I actually like and need in a bench having explored the frustrations of an existing one.

Thank you for your assistance- it is encouraging me to actually think about what I plan to build.

Nicely put, Personally I would go with just a door blank, for all the hold-fasting your likely to do over time the wear of the legs on the bench top should be minimal. All chopping (mortises etc.) should be done over a leg position so as to transfer the energy of the blows through them. I have found neither any racking or twisting in my top (15y +) and use a cabinet scraper occasionally on it to clean up, so far I haven't even gone through the decorative veneer surface, some sort of mahogany substitute, African Gabon or something...bosshogg

 

[shipbadger]

Back to the sacrificial top for a moment. Those of us who have (had in my case ) only one bench on which all activities are carried out may be grateful at times. Over the years I've upended paint pots, spilled oil from the mower engine (could have sworn I'd got it all out), knocked over paint thinners etc.. In these cases being able to quickly change the surface was a great help. Now I've a 'dedicated' woodworking bench with a groove across the top when a friend miscalculated the depth he'd set the plunge saw - c'est la vie!

Tony Comber

 

[No skills]

Seperate issue.. if you have an aldi near you keep an eye on the special buys, couple of times a year they run mixed size packs of g clamps (f clamps as well) for about £12-15. Not exactly record quality but their ok, I've used a fair few over the years.

Not sure what I would do with the top, if it was a one and only multi multi purpose bench then having a replaceable surface is a good idea for sure, if its going to end up wood only then I wouldnt bother. Laminate mdf to the door, lip the edges and jobs a good un.

fwiw

 

[LynnJ]

Just expanding on the suggestion of using screws to clamp the tops together while gluing...
If you intend to drill a number of holdfast holes, you can use these locations to add screws from the top.
Use a forstner bit to part drill each holdfast hole in the top layer only (e.g. halfway through), then pilot drill through all the layers before adding the screws.
After the glue has set, remove the screws and complete the holdfast drillings.

Regards

Lynn

 

[marcros]

good thinking. if the top is 18mm mdf with the door below, i could just mark the centres and pilot drill straight through the top. although forstner drilling now or at the end- still needs doing sooner or later.

 

[condeesteso]

I think Paul is your man for this one! Agree pretty much everything. I'd go one layer mdf on top, clamped the way Paul says (so you need some G-clamps, but you'll need those anyway). I don't believe in sacrificial tops either... it's the workpiece you 'shape', not the top. One thing - holdfasts (Richard's I mean) very happy indeed in around 50 - 65mm, above that they begin to grip less well, so your 44mm plus 12 or 15 is bang-on.
Oh yes... if you pre-drilled the 3/4 holes for holdfasts (dogs etc too) then got some scrap with the curve Paul speaks of, then the holdfasts themselves will do 2 of the clamping pieces... still need a few G-clamps though. This will also help you align the top mdf to the sub-door. I would clamp the 2 sheets together first, then whack the holdfasts in. Neat maybe??
You'll be needing some wood too, for legs etc :lol: :lol: (sorry, private joke)