Dressing Question

[Shane Watson]

So what with all the talk of Thicknessers and jointers in the Handtools & machinery forum. I want to know the hows and whys of dressing a board.

I have always used the thicknesser first to get the board to the thickness I want then I just use the jointer to square an edge so I can put it through the saw to cut it to size.

But after reading some of the responses to Barry's post I see that I should be jointing a surface of the boards first. I see this is too achieve a flat face so that when it goes through the thicknesser it will be a flat board rather than wavey. Whats the difference between the two that will make such a difference in flatness? I mean if you have to dress a board say 150x25 and its 4-5metres long. Wouldn't it be just as hard to achieve a flat face using the jointer?

I tried both ways on two small boards (150x25) aprox 1metre long this morning and both came out flat when finished. So I am assumming it has more to do with longer boards than smaller ones?

You will have to excuse my arrogance but I am self taught when it comes to machining and I am still learning, and for that matter hope to be learning till I head off to that big workshop in the sky. So teach me o'knowledgable ones http://ubb.ubeaut.com.au/ubb/smile.gif

Cheers

Shane....

[George]

Let me preface by saying that I am not an expert on machining timber either. I offer these thoughts.

It is fine to put timber through the thicknesser first provided you already have one flat face. The flat face is referenced to the thicknesser bed/tables and held flat by the pressure fingers and rollers. The blades then take a uniform amount off the opposite surface.

A board that is not already flat will be pushed flat as it moves through the thicknesser. It will resume its previous non-flat shape when it comes out the other end. The result is a board that is a uniform thickness but is not flat.

A jointer can flatten boards due to the offset in the infeed and outfeed tables. You do not need a flat face to start with.

The procedure I have seen recommended is as follows:
1.) Joint Face A flat
2.) Joint Edge C flat and square to Face A. In this operation Face A would be held against the jointer fence.
3.)Plane (thickness) Face B until the board is the required thickness. Each pass through the planer is made with Face A against the tables. Face B is therefore parallel to Face A.
4.) Rip (table saw) the board to required width. Edge C should be referenced against the rip fence. The edges are therefore parallel.

If one face of the board is already flat then you can proceed to step 2 without doing step 1.

I may not have described this very clearly but most basic woodworking texts address this issue.

Jointing a long board flat is difficult. A 4-5m board on a normal home worshop type jointer (eg Delta or Jet 6") would be close to impossible. You really need a jointer with very long infeed and outfeed tables. Roller stands etc can help but they need to be accurately set up. I'm not sure how the pros get around this. I assume they have specialised heavy duty equipment with power feeders.

I must confess I have diffulty jointing a true edge on lengths longer than about 1.2m. I did manage to joint and successfully glue up boards for a 1.8m table top with the help of a roller stand and home made outfeed table extension. Might have been a fluke though!

[RETIRED]

Gooday.

George is right in his method.

Most big places use a 4 sider that straightens and machines all 4 sides at once. This still requires a good operator and machine to get it right.

We regularly machine verandah posts up to 3.0 metres long on an 8" jointer. Practise is the key.

------------------
Ian () Robertson
"We do good turns every day"

[S Hayward]

Hi all
It is rare to pull a board from your rack, even one that was once machined dead flat, and find it is still flat. Look at Radiata Pine in your hardware to see what I mean. It is just as rare that I would ever by pass the jointer and go straight to the thicknesser. Good machining, like turning and most other things, comes with practice. As said. The long boards are harder and this is where the practice comes in. I advise to avoid the roller stands. They can cause problems as you drop off them. For really long stuff we sometimes work in pairs and also use featherboards to keep the material flat against the fence when doing edges. Really good jointers can be as long as 3m. Mine is about 2.2m which can do most things. Machining 5.0m boards is sometimes a bit acedemic when it comes to getting them flat. If they are only 25mm thick they will probably sag 100mm if suspended in the middle. You can, however, iron out the bumps on the long boards. Good machining can save a heap of hand work and improve your workmanship overall. I would generally avoid timber run through a moulder. They only partially straighten, have no sympathy for grain direction ( very important when you machine) and tend to try and press a board flat with power feeds. The board will then just spring back how it was after it has been run. Work your machines as if they were hand tools. Critically assess your machining and try to improve speed and finish. We do with every job whilst working safely at all times. When they bite, machines bite hard.
Happy woodworking.
Shaun Hayward.
Monaro Wood World incorporating the Close Shavings Wood Workshop.

[ubeaut]

My little bit is to say. "If you have the money go for the widest jointer you can (12 inches is great) with the longest possible in and outfeed tables. The work is much easier on a bigger machine."

Finally keep flesh and bone well away from the blades. It cuts easier and much quicker than timber and never, ever, leave you with a flat face. http://ubb.ubeaut.com.au/ubb/redface.gif

Cheers
Neil http://ubb.ubeaut.com.au/ubb/smile.gif

[Shane Watson]

Thanks guys!

Very informative. I must admit I rarely put boards through longer than about 3m. But I guess the princple stands no matter what dimension board.

Actually I have an under/over thicknesser. I know it is 12 inchs across but I cannot remember the lengths of the beds. I do know every time I joint something I wish the beds were longer http://ubb.ubeaut.com.au/ubb/smile.gif But I guess we all do that..

Shaun I have to agree though about not using rollers or avoiding the use of them. I even dislike using them at my parents metal workshop, but due to the weight of metal they are necessary. They obviously have there place.


Well all this can only go to improving my woodwork!

Now let me go put theory into practice http://ubb.ubeaut.com.au/ubb/smile.gif

Thanks to all!

Cheers

Shane...

[ubeaut]

In place of rollers. I have seen at Carba-Tec and I think Triton a captive bearing that when used in multiples creates a roller type support that will allow the timber to move freely in all directions. These take the place of the roller and are much safer to use and I believe are better than a second or even a third pair of hands.

Neil http://ubb.ubeaut.com.au/ubb/smile.gif

[RFNK]

Speaking of Carba-Tec, when oh WHEN are we actually going to see their much vaunted website / on-line catalogue?

Rick