Straight Edge recommendations

[Myles Moran]

I placed mine across my jointer table in multiple places, and multiple orientations (like diagonal, rotated it 180° etc). If the low or high spot moved with the straight edge, I figured it was the straight edge. If it stayed at the same spot on the table, I figured it was the table. One table has a small .005" dip, but the other was dead nuts on. I could very well be wrong, but my thought it that even if I am, the error won't be bad for me in this application.

[Darcy Warner]

Here is my favorite one. IMG_20191220_142833_980.jpg

[Patrick Walsh]

I don’t get jealous, honestly I don’t.

But you know I’m totally jealous as I have been trying to get myself to splurge on a real straight edge for years.

I keep buying actual machines. Today I just may have found a screaming deal on a 3K Lb lift table to get eh new shaper in should I purchase it.

How long is the real question?

I have a Starrett en route. If it arrives intact and checks out, you are welcome to use it for comparison to what you purchase.

A camelback in 8’ is not practical but they can be exceptionally accurate if they’re scraped in.

Starrett calls out .0002” per foot, so on 6’ that is .0012”. Plenty good, it it’s truly that accurate. Sub tool calls out .0005” per foot, so 6’ is .003”. Probably good enough and most likely sub tool is probably doing better than the number they call out.

If you can stand to wait, buy a piece of long MDF, triple it up, run 4 bolts into it and adjust those bolts to match the Starrett.

I have one hard rule, Accurate straight edges only leave the shop for inspection. Beyond that, every move they make just one more potential situation in which they may be damaged.

Be sure yo support them if you buy one, a sagging straight edge is often due to support, I have a short camelback on 6” thick x 4” thick ash, flattened and bolted to the wall.

[Gustav Gabor]

I have a Starrett 72" and 36", as well as a Veritas 38". The Starrett's are great, but I find the 72" is a bit heavy for checking jointers. The Veritas wasn't as straight as I wanted, so I modified it to be about as accurate as the Starrett. I mostly use the 72" Starrett for reference against other straight edges, or to check jointed and cut edges for straightness.

The tool I've found really valuable for machine setup, particularly for the jointer, is the 15" Starrett master precision Level no.199. They can be found used for under $200.
This level will get you fantastic accuracy, definitely enough for woodworking. It has an adjustment that allows the user to set the bubble dead-on.
I use it on jointer beds to check for twist and parallel. To check parallelism, I place it on top of an accurate 48" construction level that has been verified to be straight against the Starrett, and then check to see if the in-feed table is parallel to the out-feed. For consistency, I keep the Starrett level in the same location on the construction level while performing these checks.

A .0005 shim under one end will move the bubble noticeably. A bit finicky to use, but I've found the results considerably better than using a straightedge for setting up my jointer.
When using a level with this kind of accuracy, it's kind of depressing to watch the thick castings of my jointer deflect a tiny bit just from a bit of hand pressure...... I can't imagine how some use a power feeder....
Obviously those must be much better jointers than my old 12" .....

[Darcy Warner]

I use this every time I set up a machine.

20191230_150054.jpg

No. 98. Adjustable vial.

[Patrick Walsh]

I was using one of those on my slider by Brian lamb.

I must be a terrible mechanic as the thing drove me bazzerk.

So sensitive it’s just not realistic. Well not for me I guess.

Is the streets accuracy noted?

I use this every time I set up a machine.

20191230_150054.jpg

No. 98. Adjustable vial.

[Darcy Warner]

I was using one of those on my slider by Brian lamb.

I must be a terrible mechanic as the thing drove me bazzerk.

So sensitive it’s just not realistic. Well not for me I guess.

Is the streets accuracy noted?

It's a machinist level, its suppose to be sensitive. Lol

[Ken Fitzgerald]

Isn't the OP discussing straight edges rather than levels?

[Darcy Warner]

Isn't the OP discussing straight edges rather than levels?

Yes, but a machinist level is more accurate an easier to use for that purpose. The point is, a long precision straight edge is almost unnecessary, while a shorter one paired with a machinist level is a better way.

[Ken Fitzgerald]

Yes, but a machinist level is more accurate an easier to use for that purpose. The point is, a long precision straight edge is almost unnecessary, while a shorter one paired with a machinist level is a better way.

Better is subjective. It might be better in the mind of a machinist but for the regular, especially hobbyist user, I'd suggest that a long straight edge would be the faster method of checking straightness of the jointer beds and their co-planer relationships. That being said, you'll notice the one I bought is only 36" long and it has served my purposes well. Everyone needs to remember we are discussing woodworking not metal machining. Wood is a much more dynamic medium than most metals. A few thousandths is nothing when considering wood. Yes, there are some notable exceptions but generally speaking the dynamics in wood is such that a few thousandths is nothing.

[Brian Holcombe]

Just curious what people are using to verify the straightness of a straight edge. I worked for a company that made passenger cars for Amtrak and they had a grade A granite 4'x8' surface plate. Of course the plate was a mile away from a granite quarry that made it so it was kind of a source of pride for the QA department. With that table it would be easy to verify how accurate a straight edge is.

On anything shorter than 18" I can use my Starrett surface plate, anything longer than that I use the surface plate of a shop near me who are quite friendly and have a AA 4x8 surface plate that is inspected annually.

[Brian Holcombe]

I don’t get jealous, honestly I don’t.

But you know I’m totally jealous as I have been trying to get myself to splurge on a real straight edge for years.

I keep buying actual machines. Today I just may have found a screaming deal on a 3K Lb lift table to get eh new shaper in should I purchase it.

How long is the real question?

6', decided to splurge. I've had the want for a long while, and it will be handy to have.

Better is subjective. It might be better in the mind of a machinist but for the regular, especially hobbyist user, I'd suggest that a long straight edge would be the faster method of checking straightness of the jointer beds and their co-planer relationships. That being said, you'll notice the one I bought is only 36" long and it has served my purposes well. Everyone needs to remember we are discussing woodworking not metal machining. Wood is a much more dynamic medium than most metals. A few thousandths is nothing when considering wood. Yes, there are some notable exceptions but generally speaking the dynamics in wood is such that a few thousandths is nothing.

Lets separate 'machine setup' from 'woodworking'. Machine setup is a task in which machined surfaces made of cast iron, aluminum and steel which are supposedly made to high tolerances are set into alignment with one another. This requires proper tools to do accurately, proper is subjective certainly but so called machinist tools are not in the least out of bounds in this area.

I will pose simply that more accuracy is not harmful in this arena and generally stands to improve results and make an easier task for the person doing the setup. If you spend the entire process second guessing your tools then you're wasting your time and won't be producing a good result.

Those same checking and inspection tools are not necessarily the same tools one would use for the wood work which is to follow.

Machine shops operate in the same fashion, they have 'inspection grade' tools and 'shop grade' the two commonly overlap but the inspection grade tools are typically more accurate.

[Darcy Warner]

Better is subjective. It might be better in the mind of a machinist but for the regular, especially hobbyist user, I'd suggest that a long straight edge would be the faster method of checking straightness of the jointer beds and their co-planer relationships. That being said, you'll notice the one I bought is only 36" long and it has served my purposes well. Everyone needs to remember we are discussing woodworking not metal machining. Wood is a much more dynamic medium than most metals. A few thousandths is nothing when considering wood. Yes, there are some notable exceptions but generally speaking the dynamics in wood is such that a few thousandths is nothing.

This goes to show most haven't actually set up any real equipment besides a table saw, a small jointer and a small planer.

If machines are not level and sitting cocked, I don't care how long or accurate your straight edge is, you are not going to get anywhere.

I can't set up a moulder with a long straight edge, I need to know if it is level and not twisted. Oliver jointers are impossible to set up without first leveling the base. Big wedge bed planers need to be level before you set the machine up. Yes, its woodworking, but almost every manufacturer includes leveling the machine as one of the first steps in setting it up.

A good machinist level can be picked up fairly cheap on the used market.

[Ken Fitzgerald]

This goes to show most haven't actually set up any real equipment besides a table saw, a small jointer and a small planer.

In my case, sir, I had over 34 years experience setting up equipment much more involved than a table saw, small jointer and small planer. To level MRI magnets weighing multiple tons, we used a water line bubble and stainless steel shims. To level CT scanners, we just used machinist levels. To level x-ray equipment, again we used machinist levels.

The point is that the audience here (mainly hobbyists) may not have the education, experience or the skills, you have and therefore, the method you deem better isn't better for them. And while yes we are talking about setting up machinery made of metal, those machines are working wood which is dynamic. I am not suggesting that setting up the machine accurately isn't important, but rather, it's important to find, to use, a method the user understands and is willing to use, regardless of the time involved in using that method.

Try centering an x-ray tube on a CT scanner to the 0.00x of a mm in all 3 planes using an x-ray beam and a built-in phantom in the CT gantry. I am well aware of the importance of accuracy when it is critical. If you shot too many x-rays within a given time period, you had to walk away for 4 hours until the tube cooled back down before continuing the alignment process.

[Doug Dawson]

This goes to show most haven't actually set up any real equipment besides a table saw, a small jointer and a small planer.

If machines are not level and sitting cocked, I don't care how long or accurate your straight edge is, you are not going to get anywhere.

I can't set up a moulder with a long straight edge, I need to know if it is level and not twisted. Oliver jointers are impossible to set up without first leveling the base. Big wedge bed planers need to be level before you set the machine up. Yes, its woodworking, but almost every manufacturer includes leveling the machine as one of the first steps in setting it up.

A good machinist level can be picked up fairly cheap on the used market.

The floor being out of level by a few thou here and there should not be an impediment to quality work, provided you have a good straightedge. :^) I can understand your concern that an uneven floor would affect the accuracy of the machine, if it's that flimsy. You can always cinch it here and there, provided you have a good reference for where the accuracy matters (a decent straightedge.) Dial it in by whatever means you have.