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the great orator problem with jointer not keeping wood square
August 18th, 2005 11:54 PM
I recently purchased a craftsman 6 1/8" bench top Jointer/Planer, model 21788, from Sears, on sale. I liked the solid cast iron heft to it, along with the fence system. My problem is, I am making bedposts out of lamintated 5/4 poplar stock, and after making several runs on the machine, I have found that my posts are no longer square (more square when they were just glued), and they are "cupped" from end to end, so much as .010", which with a caliper, seems to be dramatic. The sides, out of square are also off by about .010-080" depending,. I looked at the blades and they appear to be ever so slightly out of adjustment,(laying my speed square across the two tables, at almost 0 cut, one blade barely touches, 2nd one touches and grabbs, pulling the SS about 1/8"; but when I move the SS out to the edge away from the fence, I barely catch the blade, andthe 2nd one just barely touches the bottom of the SS, moving it about 1/64") but I can't see the blades makeing such a huge difference, especially in the entire length of the board. I am newer to precision woodworking and maybe I started off with a project too technical for my own good. Any help, would be appreciated.
The Great Orator Little Help please
August 27th, 2005 10:22 AM
Well, No help yet, but I was looking at the ShopFox 6" benchtop Jointer and it appears to be identical. I looked at their manual (PDF format) and theirs is much more in depth with descriptions of various assembly, knife setting, etc. Just an FYI if anybody needs better instructions.
Randal benchtop jointer
August 27th, 2005 01:23 PM
When your running long boards over that little table, do you set up any auxillery in and outfeed tables? I was taught years ago, not to run boards more that 2x the length of the table through without doing this.
the great orator length of boards
August 28th, 2005 01:18 PM
the length of the planer is 28" and the wood being surfaced was 45", but I was using supports on either end of the table, just to be sure.
Adam Jointer usage
August 29th, 2005 01:35 AM
August 28, 2005 Jointer Usage


I don‛t know what your level of power woodworking experience you have (although first big project has been mentioned).

So... Here goes.

The jointer knives need to be set parallel with the bed and have equal extension (even with the out-feed table).

There are many different techniques and jigs that can be used to accomplish the above.

You sound very accuracy oriented. Most woodworkers deal with fractions of an inch (1/16, 1/32 & 1/64). Your use of thousands of an inch, coupled with a caliper, sounds like you might like the following article.

Checkout issue 165 of the October 2005 Better Homes and Gardens "WOOD" magazine has an appropriate two page article that makes use of a dial indicator and a special wooden jig the reader makes to set jointer knives.

The dial indicator is a simple 0 to 1 inch reading, 0.001 graduated, back lug mounted model.

Sears sells an Empire 2788 (Sears model 40777) indicator for around 25 or 30 bucks.

This same indicator (with appropriate holder) can also be used to measure run-out, end-play (thrust) and verify parallelity.

The jointer fence also has to be set at precisely 90 degrees. Don‛t rely on any machine stops. Always verify with a precision machinist‛s quality square.

Only the first jointed surface is jointed directly down against the bed. Afer establishing this one flat and straight surface, you can go on to establish square 90 degree corners.

When jointing the next two surfaces of your work piece, you need to reference the work against the precision adjusted fence and then downward. This is what gets the "square angle".

Flip the workpiece over and, using the same reference surface, joint the other side square with it.

Theoretically, you can now use either freshly jointed surface (against the fence) to joint the last surface.

With the knives adjusted even and level with the bed (out feed - left table) and the fence adjusted precisely to 90 degrees, you should obtain desired results.

Now for the "cupping" over the length of the board. The table top jointer has a shorter length bed for referencing against your work piece. It is not going to correct a long, gradual arc.

This is analogous to using a 9 inch long smoothing plane to "joint" an edge by hand. It wont cut it.

The 14 inch Jack or preferably a 22 inch Try plane has a longer sole that will ignore hills and valleys, producing a truly straight jointed edge.

You can still use the bench top jointer to good advantage on long pieces.

You will need a continuous straight edge (moving a short one is obviously not going to work).

A good commercially available product are the aluminum rules.

Sears sells several different lengths.

If your board is cupped downward (light under the middle of the straight edge), take a hand plane and "knock-off" some of the end wood on your board.

If the rule is a rocking, knock down that hill.

Don‛t worry about doing a perfect job. The board just needs to be straight enough for your jointer to accurately finish off.

Wood has a grain direction to it. Planing (power or by hand) can either be a pleasant experience or things can get nasty when going against the grain.

Make sure you take advantage of every safety device you‛ve got or can make or purchase. Jointers are very unforgiving when accidents are involved.

I still have nightmares of when my "highschool" wood shop teacher related the story of the adult school gentleman who couldn‛t wait for machine use instructions and proceed to attempt jointing a 10 inch long workpiece. It flew off the table and all FOUR of his fingers fell into the rotating blades!

Don‛t avoid your power tools. Just recognize their power and utter indifference to operator ignorance, fatigue or "experience".

I hope this is enough help for your jointer operations.

Have fun!
Adam Jointer Sharpening warning
September 9th, 2005 02:07 AM
September 8, 2005 Jointer Sharpening warning

I forgot to mention an experience that would be jointer maintenance performing people would do well to heed.

When you're loosening the Gibb screws that secure the jointer blades, be VERY careful of the counter-bored hole the screws are located in!

The word and operation of deburring seems to be used less and less as manufacturing pushes on.

I was concentrating on not slicing my fingers on the blades of a display jointer I was cleaning, not noticing the razor sharp burr on the edge of a screw access hole.

Almost lost the top portion of a finger.

If you have a Rotary Tool (Dremel), it would be an excellent investment in your shop safety to "knock the edge off" the counter-bored Gibb screw holes.
PM2790 Jointer
September 9th, 2005 02:11 PM
I see in your first post that you are using a speed square. Those will only have a 6' or 8" leg to rest on the outfeed table. Instead, use the 24" leg of a framing square. Much better contact with the outfeed table. Ideally, the blades should just kiss the square.

The other thing to check would be whether the infeed and outfeed tables are parallel to each other. Clamp a straight edge to the rear table and extending over the front table. Use feeler gauges or shim stock to determine that the table is the same distance below the straightedge at the outer edge as it is next to the cutter head.
Adam Jointer knife setting article
September 21st, 2005 07:10 PM
September 21, 2005 Jointer knife setting article


There is a detailed article on jointer knife setting (that mentions table alignment) on page 88 of the October 2005 issue of Popular Woodworking.

There is also 2/3 of a page side bar concerning swapping a standard straight-bladed jointer rotary head with a new "spiral-cut" jointer head.

That issue of Popular Woodworking also has an in-depth article about shop electrical wiring and an introduction to the joys of blacksmithing in the making of your own tools.

The last article of the magazine is an inspirational piece about how a would-be crafts person should get going, quaintly titled "Quit Crying and Get to Work".
Randal spiral and helical heads
September 22nd, 2005 12:44 AM
"There is also 2/3 of a page side bar concerning swapping a standard straight-bladed jointer rotary head with a new "spiral-cut" jointer head."

The helical heads are supposed to be better then the spiral, but while both are supposed to be better for surfacing (shearing rather then tearing the fibers), you lose the ability to do rabbits on your jointer (assuming, it's a standard rabbiting jointer).
Adam Spiral Jointer vs rabbet cuts
September 23rd, 2005 12:06 AM
September 22, 2005 Spiral jointer vs rabbet cuts


I've noticed that only the floor model jointers tend to have the ability to do rabbet cuts.

And, I have not seen many people actually use their jointers for this purpose, when there are table saws or radial arm saws with dado blades and routers to do the job.

There are also a rather large group of specialty hand planes that can create or trim up rabbet cuts.

The rabbet creators I've used include the standard black Stanley 78, with its single post guide fence and level depth of cut adjustment mechanism, the grey Craftsman (very similar - with a different cross-grain cutting system) plane and I even have one of Stanley's #39 1/4 inch dado planes.

The Record version (English company) of Rabbet plane uses a more balanced two post, guide fence system and a more precise depth of cut adjustment.

The trimming planes include all of the various shoulder planes, a rabbet plane that looks very similar to either a 9 inch smooth or 14 inch jack plane (with T-shaped blades that extend all the way to the edge of the plane) and there are a variety of old-fashioned (single bent chisel) router planes (complete with adjustable guide fence).

The spiral cut ability, however is a very desirable feature. A shearing action (similar to angling your woodworking plane) produces a finer surface, with much less tear-out.

What I especially like is the individual cutters on the new jointer head that sequentially make the "spiral".

Should a cutter become nicked, the individual cutters are indexable. And, failing that, they are all individually replaceable.

Now that adds up to finer finish (no waves), with increased productivity (decreased down-time).

I don't own a large enough jointer to make use of a spiral retro-fit head.

But, starting at $200, they're definitely worth looking into.
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