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What is a reasonable flatness spec for jointer infeed/outfeed tables?

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Forum topic by tworst posted 09-06-2010 05:40 AM 4011 views 0 times favorited 12 replies Add to Favorites Watch
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tworst

23 posts in 2300 days


09-06-2010 05:40 AM

Topic tags/keywords: jointer question joining milling

Does anyone know what can of spec to look for on table flatness for a jointer table to get good results with boards up to 12” wide? Say for infeed and outfeed tables 12” wide and around 30” in length. I know nothing is absolutely flat, and I think a decent table saw spec is around 5-10 1000ths. The thing about the jointer is it is the start of all operations when working a board and it needs to give one flat face and one 90 degree edge to that face to start as references. So it seems that jointe table tolerances are more critical than the table saw because if the jointer produced references are off, all work that follows will also be off. If anyone has some good info on this I would appreciate it.


12 replies so far

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twiceisnice

95 posts in 2289 days


#1 posted 09-06-2010 06:00 AM

some say within .005,.oo2., so on and so on ,but until you purchace your jointer and have it sitting in front of you there still might be some adjustmants that need to be made . Purchasing a jointer that is dead on is great, but sometimes it always work out that way.

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tworst

23 posts in 2300 days


#2 posted 09-06-2010 06:58 AM

My jointer outfeed table is off by .025. This measurement is not in relation to any other part of the jointer, its the outfeed table itself. I can put my Starret straight edge on it can easily rock it and visibly see the gap with no back light. I had been jointing some 2 ft long boards on the right side of the jointer and they came out OK. Then moved the fence over to the left side of the bed (just for even blade ware) and they have a very noticeable wobble when I place them on my table saw table, where as the first ones had almost no wobble at all. At that point I checked my outfeed table and found the large drop off on the left edge of the table. I thought this amount of tolerance was excessive and that is probably why my boards are coming out with a twist. I don’t think any amount of technique or adjustment can compensate for this. Any ideas out there on what I could do?

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RichClark

157 posts in 2892 days


#3 posted 09-06-2010 07:27 AM

Agree with twice better to fix something you own… Shipping and handling will dork them up anyway.

Trorst – Depending on how your Jointer is set up you can shim the outboard side with a bit of brass shim (you can by them online) to true up your outfeed side.

General Jointer info – You want the infeed as good as you can without alot of screwing around.. but you want the outfeed side to be as perfect as you feel good with. You can get (Tworst) front to back (not left to right as you pass the wood left to right so your post is kinda goofy) differences due to your table but also to the set of your knives. If you have a Spiral head then the blame is really on the outfeed table but you can tweak it with shims. good news is that the outfeed table is shimed and locked down (your should never have to adjust it again!).

Rich

-- Duct Tape is the Force! It has a light side and a dark side and it Binds the Universe together!

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tworst

23 posts in 2300 days


#4 posted 09-07-2010 03:56 AM

RichClark – I am not sure you understand. I don’t think your suggestion of using a shim will do any good in my situation. Its not that the outfeed table is drooping with respect to the infeed table, knives or anything else. Its the outfeed table itself that has a problem. When I put my straight edge diagonally across the outfeed table (that is, the the full length of staight edge is only in contact with the outfeed table), there is a big gap at the left end edge of the out feed table. Putting in a shim won’t do anything to take this out, it will just move the whole outfeed table in one direction or another, pivoting about some point. This won’t do anything to change the gap between the straight edge and the outfeed table. I really don’t think anything can be done and I think I will just have to send it back.

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mcase

446 posts in 2591 days


#5 posted 09-07-2010 05:07 AM

Reasonable spec would be .005 or less. Ten 1000ths = one 100th which is absolutely fine on a table saw, but would be very poor for a jointer. Yours sounds like its not even within one 100th which means its way out. Brands vary on what they will guarantee for flatness. There are those that may claim this kind of inaccuracy does not matter. And maybe on some machine its not that critical, but you are right that on a jointer it matters a lot. Unfortunately, I’ve found that high price does not always equal accuracy or even good service in the strange world of woodworking machines. What brand is your jointer? Please let us know. Did you buy it online or through a vendor??

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tworst

23 posts in 2300 days


#6 posted 09-07-2010 05:37 AM

mcase

I bought a JJP-12 online through Amazon. I didn’t really want to mention the name/model before contacting Jet to give them a chance to resolve the issue, which I am going to do tomorrow. My first indication that there was a problem is when I joined some boards on the right side of the table that came out OK and then did some on the left side which rocked very easily when I placed them on my table saw table. I did a check with a Starett staight edge and the error on the outfeed was easily seen, as the straight edge rocked on the table surface. I then took some thickness specified shims and found the 0.025 shim would fit in the gap. I then used several other straight edges and boards planed on the right side and found similar results in all cases. Then, I ran the same twisted boards through my old craftsman 6 1/2” jointer and they came out as good as the ones I ran on the right side of the JJP-12. I am going to use feeler gages for a more accurate result, but regardless of the error, the boards are coming out twisted. And I don’t mean that they have to be perfect, there is no such thing, but these boards were obviously twisted. I wasn’t even looking for the twist, I just happened to set them down on my table saw table and it was immeditately obvious.

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mcase

446 posts in 2591 days


#7 posted 09-07-2010 05:58 AM

Tworst,

I almost bought the JJP-12. Boy I looked long and hard at that machine. I opted for the longer tables on an 8” parallelogram, but I still love the foot print of the JJP-12 and of course the ability to joint 12” boards. Yeah, if its producing twisted lumber then it needs fixin. I sure hope they take care of this. Please let us know how Jet treats you. We’ll be rooting for you!

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twiceisnice

95 posts in 2289 days


#8 posted 09-07-2010 06:26 AM

SO YOUR SAYING YOUR OUTFEED TABLE IS WARPED.

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twiceisnice

95 posts in 2289 days


#9 posted 09-07-2010 06:32 AM

EITHER SEND IT BACK OR HAVE THE WMH TOOL GROUP CONTACT YOUR NEAREST SERVICE CENTER TO REGRIND IT IF YOUR WARRANTY IS STILL GOOD.

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tworst

23 posts in 2300 days


#10 posted 09-07-2010 06:58 AM

I would not neccesarily say the table is warped, although I believe that is the only possibility if a diagonal is off. I would need to take some more measurements to precisely state the dimesional flatness of the outfeed table. I just happened to check the diagonal first and it was so far out there was no need to do further measurements. For whatever else may be out of calibration/alignment/etc, this one dimensional measurement renders it useless to try and adjust anything. If it were just some knife adjustment, table height adjustment, or coplaner adjustment I would just dial it in myself, which I expected I might have to do anyway. But if you don’t have a plane start with, you can’t make anything coplaner.

The current problems aside, the Jet has a lot going for it. The best thing is I can face plane 12” boards to match the 12” thickness planing on the unit. This means I don’t have to rip down boards to accomodate a smaller jointer and then glue them back up and I will probably never want to glue up anything wider than 12” anyway. The joiner beds are short compared to dedicated jointers but still much longer than the old craftsman 6” in jointer I have. And with the right technique, you can joint boards longer than the bed anyway, just takes a little longer and is not as easy as having a longer bed, but everything is a tradeoff. The change over from joining to thicknessing takes less than 30 seconds and I like that you don’t have to remove anything to lift it all up as one peice as opposed to others. Having two machine in one saves a lot of space in my garage workshop. The finish from both planing and thicknessing is the same. At first, I did not like the fence, but it seems to hold the 90 degrees I mostly use it for just fine, although I have not used it much since I found the twisting problem. The fence is aluminum and the positioning system is simple and does not extrude out the back side much adding to the small foot print. Wow, I feel like I am writing a glowing review for this machine and it reminds of all the reasons I chose it in the first place. But, all is for not if the outfeed table is warped.

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RichClark

157 posts in 2892 days


#11 posted 09-08-2010 04:43 AM

Tworst – I am sorry I reread your post and goofed… Yea get them to replace it… Or get them to pony up and recommend a machine shop to fix it… I was replying to the first post in my head and yours at the same time sorry.. Your bed is obviously twisted and its a factory defect. I was thinking across the “entire” bed you saw a drop not on just the out feed side. (that you can fix with shims if the out feed is true). Again sorry…

-- Duct Tape is the Force! It has a light side and a dark side and it Binds the Universe together!

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dafus

6 posts in 1927 days


#12 posted 08-30-2011 06:52 PM

Did you have any luck contacting Jet? It occurs to me that if the table adjustments are out, the act of locking the tables down could be responsible for part of the problem. (I think the table adjustment mechanism and process is the work of the devil—six degrees of freedom and a minor pita to get at them each time you make an adjustment. This aspect of the machine surely could have been designed better.)

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