Leveling a Jointer Bed
Clear instruction on how to tweak the infeed and outfeed tables on a Delta DJ-20 jointer. May 28, 2008
Question
We use a Delta DJ-20 8" Long Bed Jointer here at our wood moulding production shop. Recently we have had problems with it straightening out boards. It almost seems as if the two tables meet at a high point; like where the cutterhead is would be the highest point. To exaggerate my point would be to take a letter "V" and turn it upside down; this is what I believe has happened to our Jointer. Does anyone have any experience with "leveling" the tables?
Forum Responses
(WOODnetWORK Forum)
From contributor A:
Both tables have to be straight with each other. Using a long straight edge see if they are. If not, loosen the fixed table and lift or budge or jiggle it to see if you can get them level to each other. Look for a gap in the table's sliding dovetail and insert a shim. Tighten up the bolts and check again.
Next check that the tables are parallel with each other by sighting from the back edges. Winding sticks will help. If the tables are not parallel with each other, re-loosen the fixed table and shim. Now loosen the knives and reset them to parallel with the back fixed table. Use brass shims if you can - old feeler gauges work fine too.
From the original questioner:
Those are some great suggestions. We just installed a Byrd Shelix Helical head on the machine. I can still reference the highest point in the revolution of the head as per your suggestion. Are you familiar with the Shelix heads from Byrd?
From contributor B:
I don't believe contributor A's advice will help with your machine as you don't have dovetailed ways to shim. Your machine uses a parallelogram type of system and you may have to contact Delta to get help on adjusting the tables. Instead of shimming to bring the tables parallel you will need to rotate eccentric cams to raise or lower the corners of the table that is out.
Before adjusting anything though, I would first get an accurate straightedge and see where the problem is. You say you've just installed a new cutterhead and now you have problems? I would start at the cutterhead. Is it perfectly aligned with the outfeed table? I would bet that's where your problem is. If the cutterhead is the high point then you probably just need to raise the outfeed table.
From the original questioner:
Thanks for your input; also very valuable. I should have mentioned that we had the problem we are having before we put the new helical head on as well. So, I believe it is not head related. We did not add the head to try to remedy this problem but to have a better finished edge on our stock coming off. We are planning on adding a stock feeder to the jointer in the near future for more consistent jointing and faster production.
From contributor C:
A simple fix on a dj-20 is to back out set screws that hold the cam adjustments in place and turn them one way or the other. That will move tables left to right or up and down. The allen head screws have two parts you have to take first one out to access the one that holds cam. The first one is a locking screw for the one under it. Start with out feed first and align with cutter head (left -right), then infeed (left-right). Take a long straight edge and check end-end. If you have hump in middle then adjust both cams on end of table at the same time to raise or lower tables. Once you have done that, recheck left-right and height with cutter. When done, re-tighten set screws and you're done.
If you have changed head from the original, chances are the cutting circle of new head may be slightly larger than the straight knife set-up which means out feed may not be set high enough to clear head when adjusting tables. Simply undo locking nut and raise table (outfeed) to compensate and tighten nut. Then bring infeed up to match.
From contributor D:
Haven't heard too many folks who know about the double setscrews to lock the cams but contributor C is correct. You need a machinist straight edge about 4' minimum to do this. It will take you some time to do this. When you move the cam the opposite corner will move the opposite way so it will be a bit frustrating at first but that's the nice thing about the parallelogram bed - it's adjustable.
From the original questioner:
Thanks guys for your help. We did work on the machine yesterday and discovered the double set screw as you guys mentioned. So, those "bushings" as we called them that house the black rods that the tables move up and down on are actually "cams" that are factory set?
If we remove the top set screw and then adjust the inner set screw that will make the adjustments? Or, do you mean that the set screws will need to be removed so that these bushings/cams can be rotated one way or the other? I appreciate the input you guys have offered tremendously. I just recently discovered this website; what a wealth of information. I look forward to spending many hours reading other threads like this.
From contributor C:
So you can turn them. The lower set screw doesn't have to be completely removed. Just loosen till cams will turn. After all adjustments are made, tighten set screws, then put locking set screws in to keep lower ones from backing out.
