Advice on sagging Jointer table (MM FS41ES)

[derek labian]

I have a sagging jointer in-feed table table that is producing concave joints (cup in the middle). This is a new MM FS41ES so this has been happening since production. Since I assumed it was factory adjusted, I thought it was my technic but its clear now its the in-feed table. Just incase anyone is wondering, it was not lifted by the tables.

I tested with a woodpecker strait edge that has .001" deviation per foot. So I would expect the edge to be no more than .002" over the span on the in-feed. I measured .001" gap at the front of the in-feed, and .010" 24" out from the edge. The full length must be further out.

My question is about what to do, I see no instructions in the manual about adjusting a sagging table. Maybe I'm missing it, but I looked twice. I read several old threads, and on other units with split tops, shimming the hinges seems to be the thing to do. I don't honestly feel I should have to do that on a brand new machine.

Sadly, I should have checked this before I started final work before a glue-up.

Any advice is appreciated.

[Kevin Jenness]

It's not clear what you mean by "sagging" or exactly what your test procedure is. I am guessing that you are resting your straightedge on the outfeed table and measuring the gap between it and the infeed with a feeler gauge, and finding that the infeed is lower the farther away you get from the cutterhead.

I'm not familiar with your specific machine so I will just speak in general terms.

Start with checking/adjusting the outfeed table height. The most common cause of convex joints is the outfeed table being too high. It should be even with or just a hair lower than the knives. This is a very fine adjustment and a dial indicator is useful here.

For checking the table flatness and alignment, the longer and more accurate your straightedge is, the more reliable the results. If you have a sliding table saw that will produce gap free joints (or a friend with one) you can make a sufficiently accurate wood or plywood straightedge, though it may not stay that way. A straightedge as long as one of your tables is minimal, one as long as the whole machine will be better. A short straightedge can give misleading indications regarding table alignment if the tables themselves have dips or humps.

Check the tables for flatness, along the length, crossways and diagonally. If they are out of the mfr's stated tolerance you may be able to get a replacement. If they are twisted you may be able to correct that by shimming.

Make sure that the outfeed table is parallel to the cutterhead. If not that may be adjusted most easily by shimming the cutterhead.

If the tables are reasonably flat, and you have determined that they are not parallel, then you will probably have to shim under the table supports. Be prepared to spend a few hours to get the tables just so. Don't start messing with this until you have eliminated the other possibilities. You shouldn't have to do this on a new machine, but the experience seems to be common. Just take your time and use a reliable straightedge.

[Brian Holcombe]

Mine was definitely setup for a spring joint from the factory, but not to the same degree you are showing if you trust that extruded aluminum straight edge.

Regardless, I would start with the basics and get the outfeed table setup first and then see how far off the infeed table is.

One of the more annoying aspects of these machines is that one side needs to be shimmed and the other side has bolts. It’s nice if they got it close enough that you can simply adjust the bolts but occasionally I’ve had to shim these machines.

[derek labian]

Mine was definitely setup for a spring joint from the factory, but not to the same degree you are showing if you trust that extruded aluminum straight edge.

Regardless, I would start with the basics and get the outfeed table setup first and then see how far off the infeed table is.

One of the more annoying aspects of these machines is that one side needs to be shimmed and the other side has bolts. It’s nice if they got it close enough that you can simply adjust the bolts but occasionally I’ve had to shim these machines.

Just to make sure I understand you accurately, your FS41ES was factory set to produce a concave cut?

The manual says nothing about adjusting infeed table, but does say, in bold letters, the outfeed is factory set and should not be adjusted.

How did you go about shimming these? Was there a documented procedure by MM/SCM?

[derek labian]

It's not clear what you mean by "sagging" or exactly what your test procedure is. I am guessing that you are resting your straightedge on the outfeed table and measuring the gap between it and the infeed with a feeler gauge, and finding that the infeed is lower the farther away you get from the cutterhead.

I'm not familiar with your specific machine so I will just speak in general terms.

Start with checking/adjusting the outfeed table height. The most common cause of convex joints is the outfeed table being too high. It should be even with or just a hair lower than the knives. This is a very fine adjustment and a dial indicator is useful here.

For checking the table flatness and alignment, the longer and more accurate your straightedge is, the more reliable the results. If you have a sliding table saw that will produce gap free joints (or a friend with one) you can make a sufficiently accurate wood or plywood straightedge, though it may not stay that way. A straightedge as long as one of your tables is minimal, one as long as the whole machine will be better. A short straightedge can give misleading indications regarding table alignment if the tables themselves have dips or humps.

Check the tables for flatness, along the length, crossways and diagonally. If they are out of the mfr's stated tolerance you may be able to get a replacement. If they are twisted you may be able to correct that by shimming.

Make sure that the outfeed table is parallel to the cutterhead. If not that may be adjusted most easily by shimming the cutterhead.

If the tables are reasonably flat, and you have determined that they are not parallel, then you will probably have to shim under the table supports. Be prepared to spend a few hours to get the tables just so. Don't start messing with this until you have eliminated the other possibilities. You shouldn't have to do this on a new machine, but the experience seems to be common. Just take your time and use a reliable straightedge.

I thought I was being clear, but sometimes its hard to read what your writing and set aside your inherit understanding of the situation.

Yes, I'm putting 1' of strait edge on the outfeed table, and cantilevering over the infeed. I tested in several positions and adjusted the infeed several times. What I posted is just the last test. In all cases there was a drop. The tables are flat. I do not have a longer strait edge on hand, but as its .010 off at 24" I don't see how that will make any difference.

"The most common cause of convex joints is the outfeed table being too high. It should be even with or just a hair lower than the knives."

The only thing the manual states about the infeed/outfeed is that the outfeed table is set by the factory precisely and should not be adjusted. It appears to be set at level not higher. At second measurement its probably somewhere perfectly above the outfeed, by maybe .001.

[Mel Fulks]

[QUOTE=derek labian;3168927]I thought I was being clear, but sometimes its hard to read what your writing and set aside your inherit understanding of the situation.



"The most common cause of convex joints is the outfeed table being too high. It should be even with or just a hair lower than the knives."

Didn’t see source of above quote, but I don’t think it’s good. The knives have to be right. The outfeed usually has to be adjusted a number
of times before the knives changed out. Even a real-small nick can make for trouble . When facing wide stuff, that nick is going to make the work “climb” ,so you have to lower outfeed . And on same project you might have to raise outfeed to make “sprung” joints. I’ve worked
a couple places where a good designer would come out of his air conditioning to joint the edge of a piece of plywood for a bird house !
Guys who are smart in one type of work ….are dumb-bells in a bunch of other stuff.
Well now I see the source, and he is a smart guy. Good writers need editors….but Keith won’t buy us any !!! The nature of forums
is constant examination. And…to our credit no one has been stabbed in this one !

[derek labian]

[QUOTE=Mel Fulks;3169160]

I thought I was being clear, but sometimes its hard to read what your writing and set aside your inherit understanding of the situation.



"The most common cause of convex joints is the outfeed table being too high. It should be even with or just a hair lower than the knives."

Didn’t see source of above quote, but I don’t think it’s good. The knives have to be right. The outfeed usually has to be adjusted a number
of times before the knives changed out. Even a real-small nick can make for trouble . When facing wide stuff, that nick is going to make the work “climb” ,so you have to lower outfeed . And on same project you might have to raise outfeed to make “sprung” joints. I’ve worked
a couple places where a good designer would come out of his air conditioning to joint the edge of a piece of plywood for a bird house !
Guys who are smart in one type of work ….are dumb-bells in a bunch of other stuff.

Just for reference, its a spiral head not strait knives.

From everything I've read, the knives should be at the exact same height as the outfeed table. If its a bit over, thats ok too (.003), if its a bit under (.001) its a problem. As far as I can tell its at level. I've ordered Brian's indicator holder so I can better test.

Its also possible, as Erik suggested, there are multiple things that need to be tweaked. I probably need to see how accurate the planer bed digital readout is now too.

[Mel Fulks]

I’ve never used a spiral jointer. Too high outfeed makes the work climb ,that is ….take off more wood at start than other end.

On long pieces it all has to be right.

[Erik Loza]

Derek, is your shop climate controlled at this point? There's a particular reason I'm asking this question.

Erik

[derek labian]

Derek, is your shop climate controlled at this point? There's a particular reason I'm asking this question.

Erik

Yeah, I installed HVAC and a commercial dehumidifier. It's nicer in there then it is in my house

[Erik Loza]

Yeah, I installed HVAC and a commercial dehumidifier. It's nicer in there then it is in my house

That's good and will help. Reason I asked is that "if" in non-climate controlled shop, there is so much unsupported cast iron hanging out past the parallelograms that I could envision a tech calibrating the machine one day, then the table moving around on the next hot or cold day. I've seen this with nesting routers that use aluminum rather than phenolic tables.

Erik

[derek labian]

Start with checking/adjusting the outfeed table height. The most common cause of convex joints is the outfeed table being too high. It should be even with or just a hair lower than the knives. This is a very fine adjustment and a dial indicator is useful here.

I checked this several more times with a couple of tools, the outfeed table is setup correctly.

[Brian Holcombe]

I don’t have a documented procedure, don’t need it personally. Remove or add shims as needed.

Doing this with a straight edge is not normally how I do it. Instead, after verifying that the tables are flat I will use a machinist level to adjust the tables.

Step one is to get the outfeed table parallel to the head at the lip and at the far end of the outfeed. Then make the infeed coplanar to the outfeed and build in the amount of concavity you prefer in your joints. I like a little bit of concavity.

[derek labian]

I don’t have a documented procedure, don’t need it personally. Remove or add shims as needed.

Doing this with a straight edge is not normally how I do it. Instead, after verifying that the tables are flat I will use a machinist level to adjust the tables.

Step one is to get the outfeed table parallel to the head at the lip and at the far end of the outfeed. Then make the infeed coplanar to the outfeed and build in the amount of concavity you prefer in your joints. I like a little bit of concavity.

I think I'd have to go to SCM support to get more information before I just start unbolting anything. I would almost certainly end up with something worse :P

Your machinist level is probably pretty short though right? Any reason you use that over a strait edge? I purchased the Lamb Tools level for the purpose but if you have a sag in the infeed side, wouldn't it be difficult to see it on a short level? Maybe you have a longer level?

[Brian Holcombe]

Yes, which is why I verify table flatness first. I have a 42” long hand scraped cast iron box section tube for that, then a couple Mitutoyo levels.

The level is going to show the effect which you are calling sag, sag is not what you are calling sag. I’m going to be persnickety, but for good purpose. Sag would better describe a section of the table that used dipped below the majority of the table, might also describe a table with a section that dips progressively as it is out of flat.

You’re describing your tabled as such but more likely they are simply out of plane and need to be adjusted into co-planar or nearly co-planar. This is easier to resolve than sagging which would not be resolvable with adjustment.