DJ -20 Jointer

[neophyte]

I have a a delta DJ-20 jointer that's about 20yrs old. I was checking the coplaner on the infeed out feed sides iofthe table. Both the infeed and outfeed are very flat as measured with a48" Starett straight edge.However ,when the straight edge is placed across the out feed side tothe in feed side a gap of .007 exits on the in feed side closest tothe cutter head.I don't see any simple adjustment screws and Idon't have the old manual.Does someoneknow howtoadjust this?

[Antiquity]

Try inserting a metal shim on the ways (where the two surfaces meet).

Dennis Bork

[msiemsen]

That is less than 1/128th of an inch. Make sure the gib screws are not too loose on the bed, on both the infeed and outfeed sides. If the knives are sharp and the jointer set up properly it may work just fine. I am not a big fan of shims but sometimes they are necessary. My 16 inch joiner had shims in it when I got it. I took them all out and it was just fine. There should be a manual online for a jointer, they are pretty much the same. Check Old Woodworking Machines OWWM.org there may be a manual or a past post on what you are doing.
Mike

[klkirkman]

I hate to be holding back the class, but is it not the case that the small offset described simply means that the  joiner cannot have the cut depth setting go all the way to zero, but that there is little practical effect as one is almost always taking a finite cut ?

I must be missing something.

Karl

[Antiquity]

Now that I think of it, 0.007" is only about the thickness of two sheets of paper.  If you are joining narrow boards you will not notice and bad effects.  And you probably will not on wider boards either.  Besides that the wider boards will most likely cup and/or twist anyways.  I would just leave it alone.

Dennis Bork

[John McAlister]

I'm sort of interested in Karl's post.  The original post says that a gap of .007 eists on the infeed side closest to the cutterhead.

As you move away from the cutterhead does the gap close up?
If that happens seems to me the 2 tables are not parallel to each other.  Which, of course can be a problem.  But----If the gap continues to exist away from the cutter head, wouldn't that mean there is no problem, other than the fact that you could not position the tables to take a zero cut?; which, as Karl points out, you wouldn't want to do anyway! 

I think I'm confused!

John McAlister

[neophyte]

I'm sort of interested in Karl's post.  The original post says that a gap of .007 eists on the infeed side closest to the cutterhead.

As you move away from the cutterhead does the gap close up?
If that happens seems to me the 2 tables are not parallel to each other.  Which, of course can be a problem.  But----If the gap continues to exist away from the cutter head, wouldn't that mean there is no problem, other than the fact that you could not position the tables to take a zero cut?; which, as Karl points out, you wouldn't want to do anyway!  

I think I'm confused!




John.

 the gap exists for only the first 7 inches.I'm guessing that the two tables are not perfectly parallel.

[klkirkman]

It might be productive to think about how a jointer works:

1. THEORY   The stock slides along the infeed table until it encounters the cutters. Iif the cutter tips lie above the plane of the infeed table, an amount of wood having a thickness equal to the rise at the cutter is removed.  The wood progresses to the outfeed table which is perfectly parallel to the infeed tabel and its top surface lies tangent to the cutter tips and the dressed stock continues to slide along a path that is a continuous extension of the path on the infeed table.

2. ERRORS 

With the cutter retracted, if the two tables are not parallel ther wood will "rock" or "rise" as it goes over the space between the tables , depending upon hand pressure.

If the cutter is not tangent to the outfeed table surface extended, the stock will "rock" or jump up and leave a skip as it goes over the space between tables, depending upon hand pressure.

Thus, for the jointer to be in "perfect" adjustment:

*  the two tables surfaces must be parallel and, of course, each table surface must be straight

* the cutter must be adjusted so that a tangent to it lies exactly in line with the surface of the outfeed table, and

* the minimum distance that the infeed table can lie below the plane of the outfeed table determines the minimum cut that can be taken.

Karl

[msiemsen]

The DJ-20 jointer has a parallelogram adjustment mechanism. Here is a link to the manual.
http://www.dewaltservicenet.com/documents/English/Instruction%20Manual/Delta/EnA06586.pdf
I don't like parallelogram beds, preferring those that run on machined ways. You may have to take it apart and bend the front brackets to be about .007 longer if that is even possible. I wouldn't know for sure without looking at it. Maybe you could sell it to a James Bond fan.
Mike

[sbachner]

If my jointer is working acceptably, and then I start getting goofy results, I know it's time to sharpen the blades. Works for me....ymmv.

[John McAlister]

This may be a little late but I believe you should be absolutely sure you've got a real problem before you do a lot of fixing. You have never mentioned what happens when you run a piece over your jointer.
Get a 3/4" board about 2-3 inches wide, and about 24" long. Measure (with a tape) the thickness at each end to be sure they are the same.  Run it over the jointer 1 time (a light cut, maybe 1/32") and again measure the thickness at each end.  If they're the same then (in this real world of woodwoking) you probably don't have a problem. Don't use a vernier caliper, you're not looking for a couple thousandths; and don't make but 1 pass over the jointer.  If you make multiple passes you'd probably get some difference anyway due to varying your hand pressure.

Try this and let us know what happens.  John McAlister

[Mark Bortner]

You gotta love the big "Made with Pride in the USA" sticker on the base. It's a shame there's a different and much smaller one for where the machine itself was made!
 
There are 4 eccentric bushings for each table in the main base casting providing about a 1/16th of adjustment. They each have a dimple in the bushing and in the base to reference how much you've moved them and 2 slots maybe 3/32 wide for a face spanner wrench to turn them. They're locked in place by set screws from above.

Before you go running for your toolbox if you want to get this just right you need to change the way you're measuring because there is a flaw in ALL parallelogram jointer designs I've seen. As you change the depth of cut the tables may not stay parallel! The mfgrs. will never admit it but it's true. You're infeed table is nearly 4 feet long and the distance between the pivot bars is just under a foot so any screw up in the machining is multiplied by 4. Since your straight edge was only halfway on the infeed table that .007 will double as well. It may not sound like much but if you're jointing a bunch of boards to glue up for something wide all of a sudden the middle of the panel is a 16th+ wider than the ends. That tension is going to make the ends open up with seasonal change for sure.
 
Now that you've checked for flat tables forget the feeler gauges. You need to set the infeed table for a 1/16 cut which is what you'll want most often. Most Starrett straight edges have a hole in the end to hang them. Mount a dial indicator in this hole and make the adjustments with the eccentrics at this 1/16 setting. It may help to cut a groove in a piece of scrap to fit over the straight edge and put a weight on it opposite of the indicator. Lock them down and check again at several different depths of cut. Don't be surprised if you never get the same readings twice! This is the kind of stuff they don't show you in the manual since their factory set-up is supposed to be flawless forever!

[John McAlister]

I've gotten out of my league!  I defer to the experts. John McAlister

[Mark Bortner]

Out of your league..... I think not! John, you've been working wood longer than I've been on this earth. I may know machinery and production techniques fairly well but I also know who the "expert" furniture maker is and a look through your gallery pics proves it! When it comes to designing and period correct methods I've got a long way to go yet.

[John McAlister]

Mark, Thank you for your kind remarks.  I truly am out of my league as far as fixing machinery is concerned but I do know whether the machinery is doing what it's supposed to do.  And neophyte has not yet said what happens when he runs a piece across his jointner.  John McAlister