Any tips for long bench tops?

[oobles]

I've read the great post on "Making a flat top (step by step)" and seen a few other table/bench tops by other members.

http://www.woodworkforums.com/showthread.php?t=61857

I'm currently building a study desk that is 3.3m long; however I only have 2.4m long boards. The boards are all beautiful 140x32mm red gum which I most definately don't want to wreck.

I figure there are two choices. One is to have two tops (one 2.4m and the other 93cm) and the other is to interleave the 2.4m boards with the 93cm boards. I'd prefer the later, however, I've got a couple of problems. How do I join the 2.4m and 93cm boards together? Do I join the boards length ways first and then glue the now 3.3m boards together as in the instructions for making a flat top? Or glue everything together at once? If I glue everything together at once how do I clamp the short and long boards length ways?

Sorry for all the questions. I did various searches but didn't turn up any other threads that would help. Any tips or links to help on the subject would be great.

Thanks,
David.

[Alastair]

Direct end joining won't work very well.

Depending on whether the desk is to be built in, or stand-alone, I would see 2 possibilities.

Split into 2 units, and get more 2.4 timber to make the 2nd half.

If you wish to continue with joining, would suggest you use scarf joints to join the planks first, and then glue up into a top, alternating the direction of the joined boards, so that the joins don't all fall in the same area.

regards

[oobles]

Thanks for the response. After extensive searching on the web the only other similar discussion I found was in the archives.

http://www.woodworkforums.com/archive/index.php/t-11931.html

I've got myself into a bit of a beginners bind having already cut the shorter lengths to size, so I can't do scarf joints. It looks like I'm going to have to use biscuits and use a long pipe clamp. The pipe clamp means I'll have to do all the glueing and clamping one length at a time; as a beginner I think this will be better anway. I'll definately stagger the location of the join and overall it should end up looking good.

[Papa]

I think I would do half laps at least. Even with biscuits butt joints are not stable.

A half lap with a mitered end would be next to scarfing.

If you already have the boards cut to length you could do a lap on
the bottom with the joiner on the under side. I would make the laps
at least 3X the thickness of the boards.

[orraloon]

When you do the glueup overlap the joints like bricks in a wall
__________ ____
______ ________
__________ ____
You see it on commercially made bench tops.
Screw wood strips on the underside to hold the butt ends together for glueup . They can be removed later.
Regards
John

[oobles]

After a few weeks work I'm pleased to say that I've made quite a lot of progress. I've got my desk into one piece. The butt joints seem to be holding ok, but I guess time will be the big test.

I've got a question regarding the corner of the desk (see picture). I'd like to put in a small rounded corner and have left enough extra length at the corner to do so. I'm wondering what the best way of doing this will be. I've recently got hold of a plunge router and figured it would be the easiest way of making the corner. However, the bits are only about 20mm high. The wood is ~32mm thick. Is it possible to get 32mm high router bits? Is there another way to make the corner? I'm also wondering how to ensure a smooth corner with the router.

Any tips would help greatly!
David.

[RETIRED]

After a few weeks work I'm pleased to say that I've made quite a lot of progress. I've got my desk into one piece. The butt joints seem to be holding ok, but I guess time will be the big test.

I've got a question regarding the corner of the desk (see picture). I'd like to put in a small rounded corner and have left enough extra length at the corner to do so. I'm wondering what the best way of doing this will be. I've recently got hold of a plunge router and figured it would be the easiest way of making the corner. However, the bits are only about 20mm high. The wood is ~32mm thick. Is it possible to get 32mm high router bits? Is there another way to make the corner? I'm also wondering how to ensure a smooth corner with the router.

Any tips would help greatly!
David.You can get a 50mm pattern bit. If it only a small radius, use a sander.

[tea lady]

Looks nice anyway. How will you get the cat to stay there.:rolleyes:

[KorDes]

Make a template of the radius you want out of scrap ply/mdf. And use a 50mm pattern bit as suggested by .

[old pete]

Hi Oobles,

This is an easy one. Join the boards as necessary end on end with dowels splines or biscuits or dominoes whatever facilities you have to hand. Then straighten and square the composite board as if it were a single entity. Edge join then as per standard joinery practice. Stagger the end on end joins across the panel width to make them less obvious.Its a big ask to pull those end on end joints tight due to the lengths involved. What you could do for this exercise is to buy some worktop top connectors or universal connectors. They are available from Hafele or Hettich or most joinery shops that do kitchen tops would have a box on their shelf. These will allow you to pull up these end on end joints very tight around the glued connections of dowels biscuits or whatever and they will not inhibit straightening on the jointer after fitting. Buy these fittings first so you will be able to see where to place the dowels etc. Please don't rely on these fittings and glue only for the end on ends as I don't think it will be successful. When you are preparing for the edge joining make sure you have a dowel or biscuit or domino close spaced in the board edge on eiether side of the end on end joint.

I'm speaking authoritively on this although in 40 years of joinery practice I've never done it myself but I've seen it in service many times and working successfully many years after installation.

The ultimate way to do this joint is to have it finger jointed with the splines in the horizontal not vertical orientation. Joinery shops can't do this but a timber engineering business might do it for you. It's standard practice in those businesses for joining up short pieces into long lengths prior to pressing up into beams etc. With the spline orientation horizontal all you see on the surface is a fine line at the join not the usual comb appearance as commonly seen in imported rubber wood table tops.

If you have trouble locating the work top connectors E mail me and I'll look up the Hafele or Hettich catalogue numbers for you.

Good Luck Old Pete

[ian]

David
I like your helper!

I think you mean taht you want to put a curve on the inside of the 90° corner

How much extra material have you left?

the easiest way is to make up a template of the curve you want from 5mm MDF – after cutting it roughly to shape, use sand paper wrapped arround a piece of 1" or 2" dowel to refine the curve
Remember that any roughness in the final curve will telegraph through when you use the patern following bit in the router

also take very light cuts with your router



ian

[oobles]

Thanks for all the suggestiongs. I ended up finding a vaneering router bit which gave me a straight edge. For the corner I used the router to get the basic shape then used the belt sander to give a nice rounded corner (great suggestion ). I'm really happy with how it turned out.. and after a lot of heavy lifting and nearly breaking it and me, I've got it in place in the study. I'll put up a pic tonight.

Now its ready for finishing. I've been reading up on various threads about Tung oil. I ended up buying some "Tung Oil" which is designed for flooring; its polymer based and probalby doesn't have any actual Tung oil in it. Somewhere on my web travels someone mentioned using Pure Tung Oil for the first coat and then using a polymer based "tung oil" for the top coats. Is this a good idea? What is the difference in finish between pure tung oil and the polymer "fake" tung oil? I'm tempted to just use the "fake" tung oil, but curious to know why people prefer the real stuff?

I'm also making three basic shelf units to go above the desk. Each shelf unit is 1500mm x 800mm and 240mm deep. What is the best join for the shelves? I was going to use a biscuit jointer and make the shelf flush with the verticals. However, I noticed another option is to use a router to inset the shelf a few mm into the verticals. Am I being paranoid and are all joins going to hold up the weight of the shelf?

Thanks,
David.

[old pete]

Hi Oobles,

That polymer based tung oil product is excellent. I use the Cabots. Sand your job to about 400 grit and clean it off carefully with turps two or three times to get up the dust. Apply a thin coat rubbed in with the grain with a 600 grit abrasive cloth and wipe off any excess after about 10 minutes with a clean cloth. Leave for 24 hours, then sand with the 600 cloth dry and get up any glar* with a clean cloth moistened with turps. Repeat the dose as before. Three goes gives a top finish. For an even more superior finish then polish with hard burnishing oil and 600 grit cloth to remove any residual nibs. Leave for a week before you do this. [ * Glar is an Irish word for gunk that transcends all human understanding ]:)

DISPOSE of all tung oil and burnishing oil rags and abrasive cloth safely on completion of each stage. Wash the abrasive cloth (its expensive) and ditch the rags outside or dry outdoors or submerge in water. Those paints are supposedly prone to sponataneous conbustion

For your shelves you want to use stopped dadoes or stopped sliding dovetails to do the job properly.You won't need fastenings. Leave the sides projecting about 40 mm above the top shelf and 60 below the bottom and put a bit of shape in the overhangs so it doesn't look like a job you would find in a prison kitchen. If you are determined to do a bodgy job then biscuits or dominoes will work OK. Put in a double layer in the ends of the shelves if you can fit them in.

Old Pete

[oobles]

Hi Old Pete,

Thanks for the advice! The finishing advice is just what I needed. I'm showing my ignorance here, but can you explain how to do the application of the polymer based tung oil? Specifically, I wasn't sure what you meant by the "rubbed in with the grain with a 600 grit abrasive cloth". Is the "abrasive cloth" just the sand paper I can get from bunnings, or is it something more specific?

In regards to the shelves, I think I'll try the stopped dadoes. (I must admit, I had to look it up on wikipedia to see what it was). Given the wood is 19mm thick, how deep should the cut be? The shelves will finish flush with the desk top, so I won't need to worry about overhang at the bottom. Also, what do you mean by "Put in a double layer in the ends of the shelves if you can fit them in." Sorry, showing my ignorance again.

As promised, attached is pic of the desk in place. It goes the length of the room so is hard to get in one show. There's some black marks from where I've just filled the holes with resin.

David.

[ian]

david

several things about finishing
1) make sure the room is well ventilated as you apply the finish and for some time afterwards
2) Old Pete warned that rags/cloths containing the finish you intend using "are supposedly prone to sponataneous conbustion". Let me be more forceful, rags contaminated with an oil based finish WILL spontaneuosly combust unless disposed of properly — as the oil dries it gives off enough heat to ignite cotton.
NEVER leave a rag with an oil finish on it scrunched up anywhere other than inside an air tight metal tin.
NEVER leave rags or paper towel with oil finish on them inside the house — make it a rule that once you have applied a coat of the finish all rags and paper towel are removed from the house.
I tend to dispose of my rags by drenching them in a bucket of water and then tossing them wet into the garbage bin on garbage night.

Stopped dados,
you wood is 19mm thick, so your dados should be 1/3 this depth say 6 to 7mm and stop about 15mm from the face of the uprights.



ian

[Stu Pocknee]

(I must admit, I had to look it up on wikipedia to see what it was).
haha! I had the same problem. And I've been reading WW mags for years! :doh:

Nice looking bench oobles :2tsup:

[oobles]

After a lot more hours than I expected and not making too many mistakes, I'm nearly done with the shelves. Thought I'd show my progress. I've got three shelf units in place. They're not fixed to the wall yet; I still need to decide how to finish them and put in the other shelves (they will be movable).

Once again, the help on these forums has been great. I wouldn't have made it this far without your help.

David.