Jet JJP-12 table adjustment procedure

A while ago I said I was investigating a good procedure for doing this, but life got in the way (twin girls came, business, etc....). I just put my shop back in order and decided to tackle it. I don't really post here anymore, but I did promise to post back with what I came up with, and I'm a man of my word, so here goes.

- throw out the manual...it's worthless
- If you're going to do it my way, you will NEED a dial indicator and a long straight edge. The alignment will only be as good as your straight edge.
- I'm going to assume that you have some working knowledge of how to use an indicator and a straight edge.

Obviously, unplug it before you start.

First remove the fence, the entire blade guard (two screws on the left bolt it to the outfeed table) and the piece of sheet metal attaching the tables to each other (4 bolts hold this on). You will have to remove the knobs for the table height adjustment too to get the sheet metal off. All this will give you free access to most of the adjustments and will decouple the tables from each other. CAREFUL...with the tables decoupled and no handle, there are lots of pinch points and the outfeed side will no longer lock in the up position. You've been warned.

Now lift the outfeed side, loosen the 3 bolts on the rear table mount and unscrew the 4 hex set screws until the mount is sitting right on the base. That completely removed that stupid mount from the adjustment procedure. It's not necessary and it's just one more variable to confuse things. On mine, that still leaves plenty of adjustment for the table height to get it flush with the knives. When that's done, torque down the bolts for good, snug up the set screws so they don't rattle, and forget about it forever. You'll never need to touch those again.

Bring the outfeed back down but don't lock it. Take your indicator and indicate off the HEAD, not the knives. Forget about the knives. Go right off the head. Pick one of the front adjustment screws and adjust it until the table is level with the head. It doesn't have to be FLUSH with the head (and probably can't be). Just level, i.e. you can drag the indicator across the head and the reading doesn't move. Now here comes the "hard" part, though it's easy when you understand the problem. When you go to lock down that adjustment screw, there is play in the threads. It's a really poor design. The locking screw should be on the BACK of the mount, not on top. When you lock down that locking screw, it pulls the bolt UP, knocking off your adjustment. With the indicator still on the head, you will have to use two wrenches and play with them as you snug it down in order to not throw off your adjustment. It's easy, but you need to understand what's going on.

When that's done, you have one more bolt left. Get that adjusted so it's just barely making contact with the table (keep an eye on the indicator) but don't lock it down just yet. Lightly lock down the table. If you need to adjust the locking post, you'll see that by removing that front sheet metal cover you now have free access to the locking post, and there's even a convenient slot in the top of the post for a screwdriver. Adjust this so it locks nicely, but keep an eye on that indicator.

Your goal with this last adjustment bolt is to make it so that the reading doesn't move when you lock it down. I can usually get it better than .001", which is pretty good. You'll soon get it figured out, but if you have no experience doing precision machine setup it will take you a few minutes to get your brain and hands wired together so that they're in sync with what the indicator is doing. When it's close, you might find it easier to lock the table and make the final adjustment locked. Anyhow, when you're done you should be able to set the table on the adjustment bolts, lock it down, and the reading won't change.

So now the outfeed is level with the head, and with any luck you'll never have to touch it again. On to act two....

Act two....

Repeat everything you did for the outfeed side up to the point that you back out the mount set screws and drive the mount right down to the frame. Snug down the mount, and from this point forward after every adjustment be sure to get those mounting bolts very snug. They don't have to be final torqued but if you leave them loose the weight of the table will NOT be good enough to get a good reading. There is a very strong spring in the mount, and it will lift the back of the mount off the frame.

Bring the infeed table down and do whatever you have to do with the outfeed height adjustment, infeed height adjustment and front alignment bolts to get the two table somewhat level. It doesn't have to be perfect. Just eyeball it so it's not way way out of whack.

Lay a straight edge across the back (table mount) side of the tables, and note which way the table has to move to get it coplanar. Again, I'm assuming that you know how to use a straight edge, eyeball things, you'll know enough to use the infeed height adjust to help with your measuring, etc. This will take forever if I describe every nuance. I'm just trying to give a reliable and simple procedure.

Once you see how it needs to move, lift the table, loosen the mounting bolts and use only the front set screws to make a tweak. Remember to snug down the mounting bolts after each adjustment, and as you do snug down the rear set screws. Basically, you're trying to make the rear set screws follow the front. If you try to adjust 4 screws at the same time, you'll drive yourself to drink, smoke and partake in other seedy activities. If you need to back out a front set screw, back out the rear ones too and then snug them back down to match the front ones.

There's a goal here. Only one side of that infeed table mount should ever have to move, and the other side should be resting on the frame. REMOVE VARIABLES. You will still want to snug down the set screws on that side to take up the little space you're creating so that you don't bend/break the casting, but the actual adjustment can basically be made with just one set screw, and the others just follow it to take up the space.

Keep doing this until you have the rear of the table pretty close. It shouldn't take long, and you'll quickly get a feel for how much to move the screw and how much it will move when you torque down the mounting bolts. On to act three......

Act three:

So let's review what we have:

Outfeed is level with the head

Infeed mount side is coplanar with the outfeed

All that's left is to level the infeed side. Follow the exact same procedure that you followed to level the outfeed with the head instead this indicate off the outfeed table. You CAN level it with respect to the head also, but you will find it more convenient if you actually get the two tables at precisely the same height as it will make rechecking coplanar simpler. Again, this is all just a matter of adjusting those two front adjustment bolts and the locking mechanism.

Now when all of this is done, you should be able to drag your indicator across the table and they're both very very level with each other (I can get mine to less than .001"). Grab your straight edge. Are you still coplanar? If so, pat yourself on the back because you're done. If not, you should only be off by a very small amount. Slightly loosen the rear mount, do what you have to do to the setscrews (take VERY small turns...it takes very little), tighten everything back down, do whatever you have to do at the front leveling bolts to make it level again, and recheck. There will be some iteration here, but the adjustments should be very small and it should be very easy.

And that's it. Double check that everything is nice and tight, double check that the readings don't change when you lock down the table (VERY IMPORTANT), reassemble it and enjoy your perfectly adjusted jointer. When you reassemble, you'll find that the sheet metal cover pulls the table out of alignment when they're not locked down. Again, this is a really awful design and I've considered splitting the cover and rejoining it with a plate and bolts so that I can snug it all down after the tables are locked. Then the cover will actually help hold them in alignment. As it is, it's livable but it is PRACTICALLY IMPOSSIBLE to properly adjust this thing in the first place with the sheet metal cover in place. Once it's adjusted, the locking mechanism will pull everything into place, but it's really amateurish.

Obviously, depending on how you've been doing things in the past, you may need to readjust your knives, and then readjust your planar bed. This is why I indicate right off the head, and in fact I have an area of the head marked with a sharpie so I always indicate off the same part of the head. Everything else can move. The head is fixed, so I align everything to that. When I change knives, I double check that my outfeed is still level with the head, and then I indicate the knives off the outfeed table. That outfeed should be very stable because of how we adjusted it. It's sitting right on the frame, remember? :)

That's it. Some other things that I find important is to make sure the base is solid. DO THIS BEFORE YOU START!! I have mine leveled front to back, but not side to side (I'm in a converted garage so leveling side to side required a LARGE shim. Whatever you do, though, do whatever you need to do with shims to make sure that the base is solidly contacting the ground at all four resting points. If you leave a 600lb machine wiggling around without solid support, it will warp the base over time and you'll be chasing around your adjustments for the rest of your life.

If you have any questions, feel free to PM me, or you can e-mail me as well (which will probably get a much quicker response). I'm very easy to find. :)

Wow! Something I'm struggling with right now! Going to read, re-read and re-read again. Thanks!!

If anyone in the Hartford, CT area is struggling with this, I will be happy to come by and help out in return for videoing the procedure while I do it. I've already had a couple of people contact me with questions. No promises or guarantees other than I'll do my best to get it humming along happily and will most likely leave it better than I found it. :)

Looks like I'm selling my house and moving to Hartford, CT. Going to pick up a GoPro on the way. :-)

Also wanted to mention that when you're done with all of this, you then need to double check that the infeed/outfeed roller heights are correct. I mention this because mine were a real mess. When the adjustment screws were practically all the way out (so much so that the jam nut could not lock the bolts...it just lifted them out of the threaded hole), the rollers were still just sitting on the casting. It was a real mess and ultimately required replacing the bolts for longer ones. It may even cause you to go back and have to tweak the knife heights....or lift the outfeed table off the base with the mount adjustment screws, etc etc. Unless yours just works out of the box, you may be stuck checking and tweaking an awful lot of things to make it work right. Hopefully understanding where the problems and deficiencies are will help you get a reliable machine.

John,

Thanks for taking the time to document this. I plan to get a Jointer/Planer combo someday and I will be able to reference this when the time comes. Nice Work!

Buy the Hammer A3. Here's the master list of changes/modifications I've had to make so far, plus the deficiencies as I see them. Buy what you want, but the A3 is FAR superior from a design standpoint, IMHO.

-front cover is only bolted down with the inner bolts, and only with regular pan heads (the countersunk screws just yank everything out of alignment).
-outfeed and infeed height adjustment levers no longer lock to the front cover
-infeed way pressure slightly increased so it doesn't need a lock to stay put anymore...friction keeps it in place
-added washer to outfeed adjustment bolt so I can lock the lever in place without locking it to the cover (hard to visualize, but if you've taken apart the machine you know what I did)
-roller adjustment bolts replaced with longer bolts. The stock ones, on my machine at least, were FAR too short, and one bolt wasn't even engaged...what the heck, Jet??
-replaced front table adjustment jam nuts with regular nuts. The jam nuts are completely inadequate and will either not hold or will mess up the adjustment bolt threads

I think I've done a couple of other things too. Here are the core deficiencies with the design:

- the front cover is a nightmare. It fits terribly, and it WILL yank your tables out of alignment. It's impossible to do a proper setup with the cover in place as you'll never get the front bolts set properly other than by dumb luck

-if you lock the handles to the front cover, again it WILL yank your table out of alignment because, again, it fits terribly-

-for similar reasons as the front cover, the fence should only be attached to the infeed table. Attaching to both tables just begs for the fence to constantly be yanked out of alignment, the tables to be yanked out of alignment, or both.

-the tables are tightened against 4 puny little allen screws for the rear adjustment. There's nothing wrong with allen screws to adjust the height, but if you're going to do that the mounts need to tighten against the side of the frame, not down on the allen screws. On my next go around, assuming I don't simply dump it for an A3, I will shim the rear mounts and kiss those allen screws goodbye. Think about it. The only think supporting the table are the threads from the allen set screws, and that tiny little contact area where they contact the frame. Yeah, that's going to be stable...not.

-table lock mechanism also tries to knock the tables out of alignment. It's a dinky little cam mechanism that engages a ridiculously long bolt. It's constantly trying to torque the table. I have mine adjusted to minimize it, but it still takes a little feel when I lock it down or it will put excess side pressure on the bolt....and knock the table out of alignment.

Basically, tables simply can not be rigidly attached to each other, you can't have ill fitting pieces yanking your careful adjustments out of alignment, and the rear mounts are mickey mouse. I'm also not particularly impressed with the fence.

After I figured all of this out, I very carefully studied the A3 manual, watched videos, looked at pictures, etc. Superficially, it looks VERY much like the Jet, but when you look carefully at the details you will see that they've addressed and fixed everyone of these problems. :)

Anyhow, the Jet can be made to work, but I think it's very hit or miss if you get a good one where everything is just perfect and stays like that forever, or if you get a whacko one where the stars aren't aligned and you need to figure out what the malady du jour is. If you're going to go for something that's not a Hammer (or other high end Jointer/Planer), do yourself a big favor and buy a traditional jointer and traditional planer. The way a normal dovetail way jointer is constructed it can hardly help but be perfect, or very close to it...even the cheaper ones.

One thing to add:

On some machines, when you bring the outfeed down to sit on the base (depending how it's setup at the factory), it may come low enough that after you adjust the knives, the feed roller adjustments are off. It wasn't an issue on mine as I had to replace the feed roller adjustment bolts anyhow, but on your new machine perhaps it would be best to simply leave the outfeed side mount alone and just go by where it was at the factory.

Again, everything worked out on mine without much trouble, but when we did Paul's we had to raise the table to get the blade heights and feed rollers back to something reasonable.

Anyhow, just an FYI. Leave the outfeed mount alone and simply live with the mounts sitting on the for set screws. I'm not happy about it, but it's better than opening yet another can of worms and having to fiddle with the feed rollers.