Jointer problem update

[Wild Turkey]

Update:  At this point I will only say that it really helps if you use a straight reference edge. 


I used a sheet of 3/4" melamine covered particle board that apparently has a curve from being stored on edge. 


Checked outfeed table and it is low on the outboard end by about the thickness of a piece of paper so I think I can take care of that.

Thanks for the help! 


Original post:
What causes a dip in the middle of a board when you're jointing it?

I haven't used my 8" jointer to make a joint in several years and when I tried to get some 6" maple ready to glue together for some work table tops (45" square) it left a 1/8th inch or so gap between the boards in the middle so I know something is out of adjustment -- but what?

I think it's a Delta but all plates have been removed in the restoration process and I can't find them right now.  It has adjustment wheels under the beds.  

I'm at the "domino" stage of moving into my new shop -- I need to finish the tables and storage racks to get the rest of the stuff moved in, but the things I need to work on those things either are in town or need to worked on -- and the tools/parts/etc are in town. 


So getting the jointer working will be the first step in getting to the next step.  Looked online and found manuals, but they were for models using a lever adjustment, not the wheels mine has.. 

Any help will be appreciated.


Here's what it looks like

[dg152]

The first thing I'd look at is your out feed table. As I think this through if the out feed is a hair low you might be getting an unwanted gap between boards. If that doesn't work I'd check to ensure that the in feed table is in line with the out feed. If they're not completely aligned then you'll get unacceptable results. I'm sure there are a number of youtube videos on how to align out feed and in feed tables which should help with the process.

[fredhargis]

Yep, generally what causes that is the ends of one or both tables are sagging slightly. I think if the blades are too high that might also be the result, you could check height of the outfeed table and see if it needs cranked up a little, that might solve the problem.

[Kansas City Fireslayer]

Any chance your wood is moving on you after jointing or are you coming right off the jointer with these gaps? Is the wood sitting for long after being jointed? I had a similar problem with maple due to internal stress. I suspected it was lumber milled from a limb as opposed to a trunk. Was your jointer working ok prior to this?

[Wild Turkey]

Any chance your wood is moving on you after jointing or are you coming right off the jointer with these gaps?  Is the wood sitting for long after being jointed?  I had a similar problem with maple due to internal stress.  I suspected it was lumber milled from a limb as opposed to a trunk.  Was your jointer working ok prior to this?

Jointed one day, checked the next.  
I've done about 50 pieces and all show same problem.
First time I've used this jointer for critical work after a full tear down because it had been sitting for so long before I got it, then it sat again before I tried to use it.

[jteneyck]

Put a 12" or so length of straight wood on the outfeed table so that it over hangs the cutter head a couple of inches.  Rotate the cutter head by hand and observe how far it pulls the piece of wood forward.  It should move it maybe an inch.  If it doesn't move the wood at all your outfeed table is too high; if it pulls the wood a couple of inches it's too low.  Check on both sides of the cutter head, too.  If the distance is different then the knives aren't parallel with the table.  

Put a straightedge across on the outfeed table, long enough to overhang the infeed table.  You should see a constant gap between it and the infeed table.  You can measure that gap with feeler gages.  It's pretty common with the type jointer you have for the tables to sag over time, but you should be able to snug up the ways to get them parallel again.  

If everything above checks out OK then the problem is your technique or the wood is moving after jointing.  

John

[Bob Vaughan]

For what its worth, that jointer is a USA-made Delta model 37-315.
1984 list prices:  37-315 jointer $1379.00, 49-054 motor and switch $474.00, 50-370 stand $329.20, total 1984 list price $2182.20.  Motor and stand had to be ordered separately in those days.  Adjust that for inflation and we have a list price of $5397.00 in 2018 dollar value.  Nice quality jointer to be sure.

I agree with others, the knives are likely to be either even with or lower than the plane of the outfeed table.
The same arched joint can be achieved by using dull knives that are set at the correct height.

[Wild Turkey]

For what its worth, that jointer is a USA-made Delta model 37-315.
1984 list prices:  37-315 jointer $1379.00, 49-054 motor and switch $474.00, 50-370 stand $329.20, total 1984 list price $2182.20.  Motor and stand had to be ordered separately in those days.  Adjust that for inflation and we have a list price of $5397.00 in 2018 dollar value.  Nice quality jointer to be sure.

I agree with others, the knives are likely to be either even with or lower than the plane of the outfeed table.
The same arched joint can be achieved by using dull knives that are set at the correct height.

Thanks -- that's very interesting information


I've put a Byrd Shelix head on it.  


I will be doing a full set-up adjustment session on it when it either warms up or I get my big wood stove going.  Working with just a propane heater limits some things I can do