How to Determine if Jointer Tables are Flat?

[Izzy Charo]

Hello,
In looking at a Jointer (J/P actually in this case), how flat is flat enough in the infeed/outfeed tables? Would you use a feeler gauge and quality (Woodpecker) straight edge... or a dial indicator for even more precision? And what would you be looking for across the width, and length of the tables for a high end machine, e.g.; Felder AD941.
Thanks,
Izzy

[Matt Day]

I use feeler gauges and quality (Lee Valley) straight edges, and try to get under 5 thou for aligning tables to be coplaner. So tables themselves need to be less than that.

[Andrew Hughes]

A dial indicator is not going to help to measure anything. I use a precision straight edge from suburban tools. I would look closely at the infeed and outfeed area closest to the cutter head.
I also have the Lee Valley straight edges.

[Rod Sheridan]

Straight edge and feeler gauge, gaps should be .1mm or less.......Rod

[Bill Dufour]

Use a straight edge and feeler guages. But make sure the edge has certificates guaranteeing straightness to some accuracy.

[John Donhowe]

Best advice I can give: buy, beg, borrow or steal a copy of "Care and Repair of Shop Machines" by John White. He has practical, common sense, and economic procedures, clearly written, on aligning/setting up a jointer, as well as table saw, drill press, planer, band saw, and other common power tools. Get it NOW! (I have no financial or other interest in the book, just a rabid fan of it).

[Al Launier]

Best advice I can give: buy, beg, borrow or steal a copy of "Care and Repair of Shop Machines" by John White. He has practical, common sense, and economic procedures, clearly written, on aligning/setting up a jointer, as well as table saw, drill press, planer, band saw, and other common power tools. Get it NOW! (I have no financial or other interest in the book, just a rabid fan of it).

I second this suggestion! It is absolutely one of the best books in my woodworkers library; my go-to book for setting up & maintenance of shop equipment.

[Gail Ludwig]

Just ordered the book on Amazon. $5 off if you order before midnight today!!! Merry Christmas to me!!!

[Bob Santos]

Should the straight edge be the full length of the table? 48" in my case. Or can I use a 36" one?

Thanks for the book recommendation! I have one on the way. Thanks to Gail I have saved $5 to be applied to a straight edge purchase :)

[Howard Pollack]

Yes, yes, yes, this is a great book! -Howard

[John Donhowe]

Should the straight edge be the full length of the table? 48" in my case. Or can I use a 36" one:)

Spoiler alert! White shows how to make a very accurate straightedge from a length of mdf- read the book before springing for an expensive straightedge. :)

[ChrisA Edwards]

Best advice I can give: buy, beg, borrow or steal a copy of "Care and Repair of Shop Machines" by John White.
Thank You, ordered it as an Xmas present for myself. (from Amazon)

[David Kumm]

Ultimately you will want a straightedge the length of the combined tables. I have a Pinske edge and when I checked it against my 8' extruded levels, I found them to be close enough to check jointers. Dave

[Steven Wayne]

I just ordered the book, too.

I bought a 50" straight edge on Amazon 0.003" across the 50" for a little under $50.

[Nick Decker]

Merry Christmas to Mr. White!

[Simon MacGowen]

I just ordered the book, too.

I bought a 50" straight edge on Amazon 0.003" across the 50" for a little under $50.

This sounds like a better deal than making your own straight edge based on John White's method (MDF & screws; I don't remember its tolerance, if ever given).

After material costs (mostly MDF) and labor (even if you are retired, your labor is opportunity cost and should be accounted for), the saving is minimal. You can resell your commercial straight edge, but not a shop-made edge.

By the way, you don't need a straight edge that covers the full length of your jointer. You only need one that is as long as the infeed OR outfeed table, whichever is longer, if they are different in length.

Simon

[David Kumm]

My 8' edge is the fastest way to determine if my tables are co planar. My Porter has a spring joint mechanism on the infeed so the straightedge veries the tables quickly. Co planar table issues on jointer planers are common enough you want a quick way to verify. Dave

[Steve Kang]

I use a one-way multigauge with a dial indicator, but you could rig up something similar out of wood if you have an indicator kicking around. https://oneway.ca/products-category/miscellaneous/Multi-Gauge