Beech posts

[muttley9050]

This is what I use although wikabor is good to. Cheaper if you buy powder though can mix with water yourself.

 

http://www.boron.org.uk/Boron_shop.htm

[Aunt Maud]

It'll be particularly important, if you make the top out of unseasoned timber, that the top pair of Leg Stretchers that go directly underneath and support the top are able to slide in their mortice as the top dries.

 

As timber doesn't shrink in its length (0.01% roughly) having a shoulder on the short stretcher tennons would possibly prevent the legs from being drawn together when the top shrinks in its width and could cause it to split.

 

A stubby full width tennon would slide into its mortice easy enough when it's drying and they wouldn't clash with the tennons for the long rails either.

 

You'd also have to make sure that the tusks were cut so that all the faces on the bench remain in the same plane, as the bench relies on these for all the clamping accessories to work.

 

I'm not sure how the top is going to be milled or if you're laminating it, but you'll have to be aware that it will also cup when drying, unless it's quatersawn.

 

As it's all going to move around when it dries you might need to do a bit of remedial work to it, so pegging it together straight away would stop you being able to dismantle it. The long through leg tennons in the top will hold it all in place if you had a 4" deep top anyway and you could probably get away with just pegging the legs in place after it had dried.

[jamesd]

It'll be particularly important, if you make the top out of unseasoned timber, that the top pair of Leg Stretchers that go directly underneath and support the top are able to slide in their mortice as the top dries.

 

As timber doesn't shrink in its length (0.01% roughly) having a shoulder on the short stretcher tennons would possibly prevent the legs from being drawn together when the top shrinks in its width and could cause it to split.

 

A stubby full width tennon would slide into its mortice easy enough when it's drying and they wouldn't clash with the tennons for the long rails either.

 

You'd also have to make sure that the tusks were cut so that all the faces on the bench remain in the same plane, as the bench relies on these for all the clamping accessories to work.

 

I'm not sure how the top is going to be milled or if you're laminating it, but you'll have to be aware that it will also cup when drying, unless it's quatersawn.

 

As it's all going to move around when it dries you might need to do a bit of remedial work to it, so pegging it together straight away would stop you being able to dismantle it. The long through leg tennons in the top will hold it all in place if you had a 4" deep top anyway and you could probably get away with just pegging the legs in place after it had dried.

 

Thanks for the detailed reply,

Is it possible for you to find some pictures of exactly the joints you mean for the leg stretchers? I think i understand what you mean but not 100% certain.

 

But from what i can gather use stubby full width tenons for the short leg stretchers (for the width of the bench) and tusked mortice and tenons for the long stretchers?

 

As for the top, i'm still uncertain as to what to do its either laminate a load of 2x4's together or cut two 4" thick 1foot wide boards as close to quarter sawn as i can get and either just put them down or laminate them together as well. Which would you say would be the best option?

 

Thanks again for the help! its most appreciated!

[Aunt Maud]

Roughly something like this.

 

I'm sure you could make some improvements if you thought about it when making the bench.

 

Turn it on its side if it makes your neck ache.

 

Now you're going to ask "How much gap do I need to leave in the mortice ?"

 

And I'm going to answer...."that depends".

Edited February 6, 2016 by Aunt Maud

[Aunt Maud]

Just noticed that I've drawn the through tennon on top of the post the wrong way round in the bottom sketch

 

http://www.timberframe-tools.com/reference/handwork-in-wood/mortise-and-tenon-joints/

Edited February 6, 2016 by Aunt Maud

[Aunt Maud]

Thinking about it a bit more, you could just get away with a bare faced tendon on the long rails as the top won't shrink in its length and neither will the long rails.

 

That'll make life easier.

[agg221]

One thing about bench designs is that usually the designer is not a miller, so they have to use what they can buy. This places limitations on the design (imagine going to a timber merchant and asking for 3off quartersawn 4"x9" please...) An advantage to using your own timber is that you can mill what you really want and use sections to best effect.

 

I think if I was trying to make a high quality beech bench and wanted to work with rather green timber, I would be inclined to:

 

Make the legs from 4"x4" and pull them in a bit from then ends.

Fit the stretchers with wedged tusked tenons so that they could be tightened up as the wood dries. Conveniently I could then also take the bench apart to move it.

Make the top either from three sections of quartersawn timber, 3" or 4" thick, or if I didn't have enough, make it from a whole load of 3"x2" or 4"x2" and if it wasn't perfectly dry, rather than gluing it together, I would run threaded rod through every foot or so, so that could tighten it up as the wood dried. M12 should do it but you could go M16 if you wanted it stiffer.

Fit the top to the posts with a mortice and tenon joint, but slot the mortices wider to the outside to allow for movement as the wood dries, then rely on the weight of the top to hold it on.

 

For now though, I content myself with benches made of old joists, mainly because the shed where I do woodwork periodically floods, so there isn't much point having a nice bench!

 

Alec

[jamesd]

Thinking about it a bit more, you could just get away with a bare faced tendon on the long rails as the top won't shrink in its length and neither will the long rails.

 

That'll make life easier.

 

I was thinking using those or just standard mortice and tenons.

 

And then wedged tusked tenons for both top and bottom short rails?

[jamesd]

One thing about bench designs is that usually the designer is not a miller, so they have to use what they can buy. This places limitations on the design (imagine going to a timber merchant and asking for 3off quartersawn 4"x9" please...) An advantage to using your own timber is that you can mill what you really want and use sections to best effect.

 

I think if I was trying to make a high quality beech bench and wanted to work with rather green timber, I would be inclined to:

 

Make the legs from 4"x4" and pull them in a bit from then ends.

Fit the stretchers with wedged tusked tenons so that they could be tightened up as the wood dries. Conveniently I could then also take the bench apart to move it.

Make the top either from three sections of quartersawn timber, 3" or 4" thick, or if I didn't have enough, make it from a whole load of 3"x2" or 4"x2" and if it wasn't perfectly dry, rather than gluing it together, I would run threaded rod through every foot or so, so that could tighten it up as the wood dried. M12 should do it but you could go M16 if you wanted it stiffer.

Fit the top to the posts with a mortice and tenon joint, but slot the mortices wider to the outside to allow for movement as the wood dries, then rely on the weight of the top to hold it on.

 

For now though, I content myself with benches made of old joists, mainly because the shed where I do woodwork periodically floods, so there isn't much point having a nice bench!

 

Alec

 

Thanks for the reply alec, just a few questions regarding your post.

 

I've got 4x4 for the legs what do you mean by pull them in a bit from the ends? Do you mean the end of the Bench?

 

I think the top will be made from 4" thick boards hopefully either two or three, they will be cut as close to the centre of the tree, but not including the pith that will be the best i can do as regards getting them as close to quarter sawn. I hope they won't move to much?

 

When you say leave a gap to the outside for the tenons on the legs to fit the top piece on what exactly do you mean? I thought wood generally will only shrink in width more than length? so would i just need to leave more of a gap in the mortise/tenon that allows the top to shrink width ways?

 

Would you use tusked mortice and tenon joints for all the stretchers? (both length and width)

 

I hope this makes sense! I might be overthinking this a bit...

[Aunt Maud]

Just forget the shrinkage in the length, it's minute.

 

Radial and tangental shrinkage are the only ones you need to consider.