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Procedure to adjust jointer tables with gibs

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Forum topic by b2rtch posted 08-22-2012 05:33 PM 3355 views 0 times favorited 9 replies Add to Favorites Watch
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b2rtch

4351 posts in 1801 days


08-22-2012 05:33 PM

Topic tags/keywords: question jointer

I have been looking for a procedure to adjust my jointer table using the gibbs.
I adjusted them last week using shims, it works well but I would like to look at how to do it with the gibbs.
I understand that this is a real pain to do it this way.

-- Bert


9 replies so far

View MrUnix's profile

MrUnix

661 posts in 951 days


#1 posted 08-22-2012 06:16 PM

Hey Bert.. what model jointer you working on? If I understand your question correctly, the gibb screws are not for adjusting the tables other than to adjust the tension on the ways. In some cases, the gibb screws may become loose and throw the alignment out, in which case tightening them back up fixes the problem. Some jointers have cammed adjustment screws that are designed to align the tables into being co-planer. Maybe that is what you were referring to? On other jointers without the cammed screws, then shimming the ways is the way to do it.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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b2rtch

4351 posts in 1801 days


#2 posted 08-22-2012 06:32 PM

I ma working on a Powermatic 60 from 1974.
It was my understanding tot at first that the gibbs are just to allow more or less play in the dovetails but since then I read that in fact the gibbs are used to adjust the tables parallelism and height.
I just do not quite understand how it is done.
If I fully tighten the gibbs then the tables are not parallel to the cutting head nor to each other and they are not co-planar.
They are not far out of adjustment ,but they are out of adjustment.

-- Bert

View pintodeluxe's profile

pintodeluxe

3570 posts in 1565 days


#3 posted 08-22-2012 06:42 PM

I just take a 4’ builders level, and an automotive type feeler gauge, and adjust for coplaner.
When a .002 gauge will slide in with the same resistance on the infeed and outfeed tables, you are coplaner.
Even being off by .05 will create tapered cuts after multiple passes.
Best of luck!

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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b2rtch

4351 posts in 1801 days


#4 posted 08-22-2012 06:51 PM

I just called Powermatic to ask for instructions.
Very nicely they send me the instructions for a Jet JJ-8Cs , which seems indentical to my powermatic 60.

-- Bert

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b2rtch

4351 posts in 1801 days


#5 posted 08-22-2012 06:57 PM

In the manual they say t adjust the gibbs to remove the play in the tables but they say nothing about using them to adjust the tables.

-- Bert

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MrUnix

661 posts in 951 days


#6 posted 08-22-2012 07:08 PM

Yup.. that’s all the gibbs do. Usually, I just snug them up until the table is difficult to move with the adjustment knob, then back if off a hair. Like I mentioned, sometimes people will have a drooping table and tightening the gibbs up will pull it back up into alignment. But that is simply a result of the gibbs having loosened over time or due to wear on the ways. If your tables are actually out of alignment, then shimming is the most common option for those without the cammed adjustment screws.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

View Mainiac Matt 's profile

Mainiac Matt

4484 posts in 1081 days


#7 posted 08-22-2012 07:15 PM

I’ve seen a description of a procedure for scraping the gibs on milling machine ways (some of which can use tapered gibs) over on the cnczone.com forum and they link a Youtube video by a German machinist showing his technique.

I was quite impressed (and somewhat baffled) by the process…. it looked quite involved and required some precision measuring of the angles and the use of a granite plate and set up blocks to accurately reproduce them.

If I’m not mistaken, at the factory, they assemble the tables, base and gibs, and then run the complete assembly through a jumbo sized Blanchard type surface grinder. So that particular set of gibs (with any slight variation in geometry) becomes custom to that specific jointer.

On my 1930s vintage Sears 6” jointer I tighten the outfeed gib screws and gib lock screw quite tight and then set the blade height to the outfeed table…. Then I never touch them again, unless something goes out of whack.

The infeed table gets moved a lot more and I so I suspect these are the gibs that are much more prone to ware. I keep just a thin coat of grease on the ways and then snug up the gib screws untill I can just move the table with the handwheel… Then I tighten the gib lock thumb screw with pliers, as any play in the gibs will make the infeed table prone to sag at the ends… especially for a big long 8” beast like you have

OBTW… the gibs are usually made out of a soft metal like brass, to ensure that they ware and not the dovetail ways.

-- Pine is fine, but Oak's no joke!

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b2rtch

4351 posts in 1801 days


#8 posted 08-22-2012 07:30 PM

On the Powermatic they are made of, what looks like,steel.
My tables are no pretty good and every direction but I used steel and brass shims to adjust them.
I adjusted first the in feed table to be parallel with cutting head then I adjusted the out feed table to be parallel and at the same eighth than the cutting head.

-- Bert

View Mainiac Matt 's profile

Mainiac Matt

4484 posts in 1081 days


#9 posted 08-22-2012 07:35 PM

I’d lock it down and call it good to go then.

-- Pine is fine, but Oak's no joke!

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