Thread: HELP - Jointer produces tapered boards

Gooday. I would hazard a guess and say that you are applying too much pressure on the outfeed table without maintaining any on the infeed.

It could also be that the outfeed table is dipping at the end away from the cutter head. Check that the gib strips are properly adjusted.

It is an acquired feel and practise is the only answer.

Where do you live?

My guess would be that the outfeed "table" is not set up EXACTLY level with the blade. It looks as thought the blade is a bit low??

If the blade's too high and you'll get a tapered board, too low and you'll get a convex result if you end for end them to try to even them up (or is it the other way round??)

Fortunately it's pretty easy to correct, use a plastic rule across the face of the blade and adjust till it touches. Try this link for instructions; http://www.woodcentral.com/bparticle...justment.shtml (they use a metal rule, but I prefer plastic in this instance!)


Cheers,

P

Originally Posted by

Gooday. I would hazard a guess and say that you are applying too much pressure on the outfeed table without maintaining any on the infeed.

It could also be that the outfeed table is dipping at the end away from the cutter head. Check that the gib strips are properly adjusted.

It is an acquired feel and practise is the only answer.

Where do you live?

, what are gib strips?

To start with I have a Jointer the same as yours and the only thing wrong with it is that it's not an 8" jointer. First check that when wound up level both your infeed and outfeed tables are in a straight line, use a straight edge.
That said, my method of setting up the relationship between blades and outfeed table is this Assuming that all your blades are sharp and set at the same height, lower your infeed table, then take a piece of straight edged board and put 2 marks on it exactly 2mm apart. Lay it on your outfeed table with one mark right on the edge of your table then, having disconnected the power, rotate the cutter head in the direction of cut. Your outfeed table is set to the correct height when the board moves exactly 2mm.
There may be differing opinions on this matter but it worked for me during 20 yrs of joinery shop ownership and it still works for me now.

Your method is correct, the tables are not in plane. The outfeed table is low on the far side. Instructions should tell you how to align the outfeed table. You will need a good straight edge. There are machinist straight edges that are made for this purpose, if you can't borrow one ( they are quite expensive to buy)buy an aluminum 2'x2" angle. They are good enough to set up your jointer tables. At worst you may have to shim the outfeed table dovetail ways.There are websites that may help you better than my post.

mike

Hi Gary,

I too have produced a few 'tapered' boards. After checking the set-up I looked at technique of feeding the timber. Applying even pressure on the timber fixed a lot of the problem but by far the best fix was to alternate the feed direction on the timber. Eg With the grain, then against the grain.

Yep, going against the grain does not produce a very good finish but it is flat. With sharp blades and light cuts its not too bad and finishing with the grain takes out any marks.

Some might say never cut against the grain but I'm happy with the results I get now. I do however get some variation of thickness for the first 50mm on each end of the board caused by the thicknesser. I just allow for this waste.

Glen.

Hi Gazza,

Don't know where you are but I would reckon than any and/or all of the above may be the problem.

Do all of the above and pay attention to the following;

Make sure the in and out feeds are parallel.
Use wooden straight edges to ensure the tables are in alignment with the cutters.
You can use feeler gauges to ascertain the differences if you need to.
With all that set adjust your infeed to the depth you want to cut - in my opinion less is often better. Again use a wooden graduated straight edge to ensure it moves the same distance on both sides of the blades when you rotate the head.

Geez it's harder to describe than say or demonstrate :eek:

Depending on the condition of the timber you are trying to dress there is some experience you will need to gain as to which way to apply the piece to the cutter to get the best use of the stock you are using. Again end for ending the piece will help but you need to use your knowledge to get the result you want.

Remember that the jointer is just an automated plane and the results you get will be dependant upon your skill and application of the tool. You can't expect it to magically square, straighten and correct thickness without you controlling the process.

Hope that helps

Jamie

Also depends a lot on what you start with. If you are jointing a bowed bit of timber (is that right, Rocker?) then you want to put the convex side down and start by sitting the leading edge on the outfeed table over the blade so the extreme of the bow is sitting near the back of the infeed. This gives you two reference points that will move in plane with each other: the bow and the bit that is being cut. Depending on how bad the bow is, the next pass can be as per normal. This will cut the guts out of the bow, rather than follow it. Never put the concave side down as the bow will ride the far edge of the infeed table and force the board up as you push it through.

That's assuming the board is longer than the infeed table. For badly bowed boards, we used to trim the bow off one side with a circular saw and clamped straight edge, then joint that side, then run it through the table saw to make it parallel.

Don't know if this is your problem or not but the picture you drew reminds me of what it looks like if you try to joint a bowed board using the leading edge of the board as the reference.

If you get everything in plane and adjusted right, then it only leaves technique.

Originally Posted by silentC

If you get everything in plane and adjusted right, then it only leaves technique.

Said the choir girl to the bishop.

Originally Posted by AlexS

, what are gib strips?

Gib strips or plates are the liittle bits of steel/brass that go between the main body and the sliding part of most machines with sliding components.

They are tightened, generally, by an Allen grubscrew and lock nut.

Their purpose is to allow parts to slide without sideways or up and down and to provide a wear area that is easily replaceable.

I hope that answers it and if any one else wants to chip in feel free.

To see what I mean.

http://www.mini-lathe.com/Mini_lathe...tm#adjust_gibs

Thanks .
A day is not wasted if you have learned something.

I am not sure that you are not confusing the job of a jointer with the job of a thickness planer. Forgive me if I am wrong, but you mention you are getting "wedge-shaped boards" when the role of the jointer is to give you a reference face and edge. Once the face is achieved you put the piece into a thicknesser to achieve a coplaner, even thickness board.

Originally Posted by silentC

Also depends a lot on what you start with. If you are jointing a bowed bit of timber (is that right, Rocker?)

Er, no! As I understand it, you are talking about edge jointing. If the faces of the board are flat, but its edges are curved, then it is 'crooked' or 'sprung'. This is the mode of warping that you are referring to, SilentC.

If the board's faces are curved from end to end, then it is 'bowed'. To correct this on the jointer, the board is laid flat on the jointer, not on edge.

If the board is curved across its width, from edge to edge, it is 'cupped'.

I have attempted to show the three types of warping in the attached drawing.

For a more detailed explanation, see Bootle's book 'Wood in Australia', p. 53.

Rocker