What should I expect for cast iron tolerance on new Grizzly 76” jointer tables?

[Bob Spryn]

Hey there,

I’m curious if what I’m seeing is below a reasonable level of tolerance on the outfeed table (just the cast iron, not involving cutter heads).

From front-left to front-right on the outfeed table (away from the fence) I get a .002” variation, which is great. From back-left to back-right I get maybe .005”, which I guess isn’t awful? But from front-left to back-right I see a roughly 0.011” scoop in the middle.

Measuring with a 36” straight edge that should be within .002.

I got the outfeed edge within .001 with the cutters from front to back (well, the cutter body, challenging to do on a helical head) using a dial gauge. It’s pretty flat for maybe the first 8-12 inches, then some of that scoop in the middle variance kicks in. I’m not sure how much I should worry about this.

[Richard Coers]

You won't see any difference in any of those tolerances. And since you only know what your straight edge tolerance should be, the measurements might be off a couple thou.

[Bob Spryn]

You won't see any difference in any of those tolerances. And since you only know what your straight edge tolerance should be, the measurements might be off a couple thou.

Ok thanks. I had heard others seeing their tables having .002 tolerances all the way through so I was concerned.

[Andrew Seemann]

I wouldn't worry about those numbers. I seem to remember something about jointer tables being around a hundredth for tolerance.

I knew some folks who owned a local shop that sold wood machinery (now retired). They said that most of the people that fiddled with new jointers to make them "more accurate" usually ended up making them worse than what they stared with, to the point where sometimes they would have to send someone out to fix them.

[Lee Schierer]

Does your jointer have adjustable gibs? You might be able to adjust the gibs to take out some of that dip.

[Brian Holcombe]

Those tolerances are way off of what I personally consider to be acceptable. Most offensive is the .011” dip. I have a SCM jointer/planer that is flat to less than .002” over the whole surface.

[Kevin Jenness]

The question to ask is, does it work? If it doesn't work, what can you do about it?

Start by setting the outfeed table even with or just below the knives. Joint a pair of flat 1x4s as long as the outfeed table and offer up the jointed edges to each other. Do that at the right, left and center of the machine. Can you get a tight joint? If not, adjust the outfeed table height in minor increments. If you can't get the results you want, beg, borrow or buy an accurate 6' straight edge and check that the tables are in plane. Adjust them as close as you can if needed and try again.

If you truly can't make the machine do what it is supposed to do, document your findings and talk to the seller. If it is out of their stated tolerances they should replace it. Grizzly has a decent reputation for customer service, but I suspect your machine may be within their standards. In my opinion .011" over 36" on a jointer table is pretty horrible and not likely to result in accurate work, but the proof is in the pudding.

[Myles Moran]

On my grizzly, I'm within about .002 everywhere I can tell (I won't pretend I'm an expert at feeler gauges and a straight edge). I did however find the back left side of my outfeed drops .005 or so. When I'm edge jointing a glueup, I'll usual slide the fence to the middle to avoid that drop, since I generally have to check and resquare the fence every time I edge joint. That said, I've never noticed anything bad from my .005 drop, and I've found more issues are created from bad technique - if I'm not careful about how much (well, little is probably a better word to use) I can end up with a non-straight edge joint, but if I'm careful to just barely guide the wood through the machine and not push on it more than I absolutely need to I get better results.

[Bill Dufour]

Why do you think your straight edge is accurate? HAs it been stored correctly so it has not lost that accuraqcy?
Bill D

[Bob Spryn]

Why do you think your straight edge is accurate? HAs it been stored correctly so it has not lost that accuraqcy?
Bill D

Yeah it’s been hung on the wall in the mountable storage it came in. Also checking against other flat surfaces (cast iron tops and granite countertops) I only see about a .002 degree of variance.

[Bob Spryn]

On my grizzly, I'm within about .002 everywhere I can tell (I won't pretend I'm an expert at feeler gauges and a straight edge). I did however find the back left side of my outfeed drops .005 or so. When I'm edge jointing a glueup, I'll usual slide the fence to the middle to avoid that drop, since I generally have to check and resquare the fence every time I edge joint. That said, I've never noticed anything bad from my .005 drop, and I've found more issues are created from bad technique - if I'm not careful about how much (well, little is probably a better word to use) I can end up with a non-straight edge joint, but if I'm careful to just barely guide the wood through the machine and not push on it more than I absolutely need to I get better results.

Interesting. I’ve seen advice to put pressure on the outfeed side once it passes over the cutter head. I’ve not heard people explain to put minimal pressure on that side, although that does make some sense so you aren’t forcing the wood into a position it doesn’t naturally want to be in. I have used that technique with some thin boards on my little bench top jointer I had.

[Alex Zeller]

My personal take is that some people expect perfection even when it's not needed. Ask yourself this. When jointing the face of a board does it really matter if it's off by .010"? For most of us, not at all. When it comes to gluing up two boards to make a wider one where a nice straight edge is needed when is the last time you've had a project that needed boards wider than an inch? In the last 5 years I've only done it a couple times. The last time was to make some 4" square posts for a bed frame out of 4 triangles. Even then they were only a foot long and getting an exact 90 degree angle so they all came together nice and tight was the challenge.

When facing a board it leaves the jointer, goes to the thicknesser, and then most times the board movement from the newly exposed edges causes a slight amount of movement. Maybe in a perfect shop with wood that's been dried to perfection and has had years to climatize to your perfect shop this may not be the case.

The G0858 is a parallelogram jointer so you can try to set the two closest bed adjusters to match the head, adjust one of the rear adjusters (with the other loose) to get the bed parallel to the infeed table, lock those 3 down, and then try adjusting the forth adjuster to force the table to be less twisted.

[Myles Moran]

Interesting. I’ve seen advice to put pressure on the outfeed side once it passes over the cutter head. I’ve not heard people explain to put minimal pressure on that side, although that does make some sense so you aren’t forcing the wood into a position it doesn’t naturally want to be in. I have used that technique with some thin boards on my little bench top jointer I had.

Correct, I am trying to hold the wood onto the outfeed table, but very gentle in the process. Imagine a cupped or bowed board that flattens out with pressure - you're right about you making it "flatter" for the jointer and it springing back after.

I can't remember if I had a concave or convex edge joint when I learned this, but the problem cleared up right away when I used a gentle touch.

[Ken Fitzgerald]

This topic has been discussed/argued many times here at SMC. IIRC, most manufacturers have a tolerance of 0.015. Realistically, 0.011 is 1/90th of an inch. I'd say it's an unfair comparison to compare a Grizzly machine to say an SCM jointer/planer because of the price difference when they were both new machines. If I paid 2-5 times as much for a machine I would expect tolerances, fit and finish to be better too.

First, what is the accuracy of the straight edge? Second, I'd call Grizzly to see what their advertised tolerances are, (2) what they recommend and (3) then try edge and face jointing a board to see what the results are.

[Bob Spryn]

I’m pleased to report that I’m a complete bonehead. I *did* manage to introduce that gap by causing a twist. After getting some sleep I went back out there and took a bunch of measurements and thought about the geometry and figured I would test if I could remove the gap. I’ve got it all back down to roughly .002, and now I’m trying to keep that tolerance while getting the outfeed coplanar to the cutting head. It’s pretty difficult to do with the helical cutter head, but the One Way tool is helping me find the high point.

I’m getting the hang of the small adjustments and checking all the different angles, but it takes time.