Looking for affordable straight edge for jointer tune up

[Peter Christensen]

Carlos I believe he is talking about these types.

http://www.starrett.com/category/job...&sortBy=wp/asc

[Rod Sheridan]

I use the Lee Valley 36" straight edge

http://www.leevalley.com/en/wood/pag...40,45313,56676

regards, Rod.

[Brian Backner]

Somewhere I remember reading an article about creating precision straight edges for aligning jointer beds using three pieces of relatively straight wood/MDF/plywood and a handful of drywall screws.

Basically you would put four or six screws into the edges of the boards at the same locations (1" from both ends, 18" from both ends and 30" from both ends - or to suit the lengths of your infeed/outfeed tables). You then take two of the boards, lay them down and touch the screw heads together and adjust them in or out so that they all touch perfectly. Then reverse one of the board end for end and do it again. Then take one of those boards and adjust the third board to the second. Then go and adjust the first board to the third. If you do this three or four times, you can get the screw heads in the same plane within a few thousandths of an inch. It's a similar process to what machinists do to create perfectly straight or flat surfaces by "scraping."

I haven't done this myself and i will try to find the reference and post a link here if I can find it.

Edit: Of course you will need to do this to the three boards each time you adjust the jointer as, unlike metal straight edges, the wood will move!

[Mike Heidrick]

I don't understand the point of spanning the entire table surface. I adjust mine with about a 30" tool, and that seems like plenty to assure the tables are in alignment. Is there really that much more precision to be found with a longer one? (Prepares to break out wallet to feed OCD)

I sure want more than a 15" span per table. Just me though.

[Chris Fournier]

In John White's "Care and repair of shop machines" he describes making a set of "master bars" for this purpose. They are not as versatile as high dollar straightedges, but for setting up machines they can easily be accurate to 0.001" over 6', and are almost free. You simply put three screws into the edge of a board, adjusting to make a pair of the bars match perfectly. They key is to make three of them, making each match the other two, which guarantees straightness. White describes this in detail, as well as their use.

Yup! Made a set about 25 years ago to set up my jointer during an OCD phase in my life. Great exercise, inexpensive and did the job.

[Brian Tymchak]

I sure want more than a 15" span per table. Just me though.

I was thinking the same as Carlos but that assumes each table is flat over its length.

[Robert Hayward]

Here are a couple of long straight edges. I use a Crane 48" one.

http://www.tools4flooring.com/crain-...-ft-p-533.html

http://www.tools4flooring.com/gundla...SABEgLWJ_D_BwE

[Peter Christensen]

Here are a couple of long straight edges. I use a Crane 48" one.

http://www.tools4flooring.com/crain-...-ft-p-533.html

http://www.tools4flooring.com/gundla...SABEgLWJ_D_BwE

Do you know if that .003" is per foot or for the entire length?

[Brad Shipton]

I needed a 10'-0" long straight edge and the local machinist suggested keystock (https://www.mcmaster.com/#key-stock/=1cxc44p). It turned out to work very well for what I needed to do. I checked it by running my 36" straight edge along its length using feeler gauges to find high or low spots and it was well within what I could measure with feeler gauges.

[William Hodge]

What's happening that makes you need to tune up the jointer?

There are other issues that can make a jointer cut unsavory shapes, and they can be easier to solve before getting the tables co-planar. For example, if your outfeed table is too high or low, the wood won't be flat. I like 1/2" of snipe. If you bear weight on the infeed table or use a push block at the tail end of a board, you could be forcing the wood to not be flat. One or both tables could be bowed or twisted, or not lined up with the cutterhead evenly.

A machinist told me to use a taught wire tight to the outfeed bed, and shimmed off the infeed end of the infeed bed with the infeed bed lowered. With feeler gauges, you can check the distance between the infeed bed and wire. This is more appropriate on bigger jointers.

Wlliam Hodge

[Edwin Santos]

I don't understand the point of spanning the entire table surface. I adjust mine with about a 30" tool, and that seems like plenty to assure the tables are in alignment. Is there really that much more precision to be found with a longer one? (Prepares to break out wallet to feed OCD)

It's because you need to do more than just confirm alignment of infeed table to outfeed table at the cutterhead. You also need to determine if the two tables are in the same plane. A long straightedge will allow you to assess whether the two tables are pitched down towards each other like a valley, or vice versa like a hill. To do this ideally you would want a straightedge long enough to touch the end of each table so you could go with feeler gauges along the straightedge to see if the gap is consistent. The shorter the straightedge, the harder it is to detect the error.

Jointer alignment can be maddening. It's also possible that one table is in the correct plane and the other is "tilting". Less common, it's also possible that they could be out of alignment from back side to operator side, in relation to each other.
Edwin

[Peter Christensen]

Well if you really want to get the jointer as close to perfection as possible get a portable Coordinate Measuring Machine (CMM) like a Faro or Romer Arm and you’ll be able to measure and map the flatness, parallelism, straightness, twist of the tables, and fence plus perpendicularly. Then you can address the out of tolerances and when done verify the corrections. It’ll only cost you $40,000 to $80,000 and you can then go on to check the rest of the machines in the shop.

Now I’ll take my tongue out of my cheek.

[lawrence munninghoff]

Is the powertec straight edge the same as the veritas straight edge?

[Mike Kees]

You have two choices ,pony up for a straight edge or build the 'Master bars' that Alan suggested from John Whites book. I have this book and it is an excellent reference for all the major shop machines. I bought my straightedge before I found the book otherwise I would have tried out this method. Mike.

[David M Peters]

Peachtree woodworking has a few reasonably priced aluminum straightedges that I use for my jointer.