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Perfect Square? Perfectly Flat? Perfectly Straight?

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Forum topic by VillageBoy posted 128 days ago 687 views 0 times favorited 11 replies Add to Favorites Watch
View VillageBoy's profile

VillageBoy

62 posts in 1017 days


128 days ago

After rotating my jointer blades yesterday and taking a test pass, I noticed some serious snipe on the front and of the board. I checked my out feed table height and noticed that it had some how become to low or too high? Maybe I wore the cutters unevenly on one side?

So I start going through motions of checking the table parallelism. I have only had to do this once and I used the ruler from a Swanson T Square and everything worked out ok.

I followed the same steps as last time but this time I notice that there is a small space of daylight between my table and the ruler. Is this normal?

So I put my 36” WP straight edge rule on the table and the daylight between straight edge and table almost disappeared.

So my questions:

How straight is straight when choosing an accurate straight edge?

How flat is flat when jointing and planing a board? Within 1/16”, 1/32”, 1/64”?

And is it possible for my jointer tables to be slightly bowed? (Grizzly G0609X)

My skills are advancing a bit but am still a beginner at wood working. Your input and oppionions would be appreciated very well.

The Pursuit of Wicked Gorgeous Lumber, A Noble Undertaking
Village Boy~


11 replies so far

View Redoak49's profile

Redoak49

263 posts in 586 days


#1 posted 127 days ago

I bought the Lee Valley 36” aluminum straight edge. In the case of setting up a jointer or planer, I think that you need something that is as straight as possible. On this straight edge, they say it is machine flat to 0.003” over the entire length.

I think that a good straight edge and feeler gauges are a necessity for setting a jointer. The other thing it requires is the patience to take the time and get it right. The first time may take you some time but the results are well worth it.

Good Luck

View Bill White's profile

Bill White

3342 posts in 2558 days


#2 posted 127 days ago

Remember that you’re working with a medium (wood) which can change dimension from day to day.
Don’t get obsessed. :)
Bill

-- bill@magraphics.us

View darthford's profile

darthford

532 posts in 521 days


#3 posted 127 days ago

I purchased an iGaging 36” ground straight edge from Grizzly for $54. They claimed it was ‘precision’ and ground to an accuracy of .001 inch. I dubbed it utterly useless JUNK and returned it. It was both bowed along its edge and along its side. I had purchased it specifically for setting up my G0490 jointer. I ended up using my precision Starrett 24” satin chrome ruler. You get what you pay for I have given up buying cheap measuring tools.

View TheWoodenOyster's profile

TheWoodenOyster

600 posts in 532 days


#4 posted 127 days ago

How straight is straight when choosing an accurate straight edge?
- IMHO, 99% of us can get by with a good 4 foot level. I have wanted an aluminum straightedge, but there are a gazillion other tools that I think would be more beneficial. A good level should be around .005 or so over the 4 feet. That is a pass or two with a plane. I use stock straight edges on plywood and they usually work out great.

How flat is flat when jointing and planing a board?
- This one really depends on the length. For a short board, under 3’ or so I think 1/64” is about right. Over that, you could live with 1/32”. Attaining perfect flatness is a tough chore. Between internal stresses and human error, you are likely to turn half your board into shavings before you are done on the jointer. Use your best judgement, but see Bill’s comment above, and don’t worry too much.

And is it possible for my jointer tables to be slightly bowed?
- Maybe. It is very possible that your jointer just isn’t set up totally perfectly. My jointer was acting goofy the other day and I realized that my outfeed table had moved around. I took a little time to get it close, but getting it perfect is nearly impossible and is about like water torture.

Now just a little of my own experience. When I started woodworking, and as I continue woodworking, I have found the jointer to be far and above the most difficult power tool to set up, use, and use safely. I used to obsess a lot about getting everything setup just right. There is something to be said for that, but when I want to set a jointer up perfectly, I’ll buy one that lends itself to being accurately adjusted. My jointer right now is a decent little 6” Jet, but it is on dovetailed ways and I never want to take it apart and do the whole shimming it to level with brass shims thing. That would literally be easily a 15 to 20 hour project, likely more. I’ll take a little inaccuracy and keep my woodworking time. And, as a side note, don’t be afraid to throw something right into the planer sometimes. Not everything has to be jointed, though many things do.

Again, don’t obsess too much. It’ll never be perfect, especially when you get into longer boards. That’s what makes us craftsmen as opposed to robots. Robots can’t clamp out a little twist. ;)

-- The Wood Is Your Oyster

View unbob's profile

unbob

361 posts in 501 days


#5 posted 127 days ago

A really good straight edge would be a Brown & Sharp cast iron camel back style, accurate to around .0002” in 36”. that one weighs around 50lbs.
That type of tool is for rebuilding machine tools, and other close tolerance uses.

A Starrett steel straight edge in 36” length, maybe about .001” to flat.
In my view, that would be the minimum tool for adjusting woodworking machines.
Aluminum is not known for being anything close to a straight edge.

My view is different, for example, I have an older Grizzly 8” jointer, it is within .002” flat both tables, that did not happen on its own, I put 10hrs into it.
In working anything, accumulative errors build up from many factors. To help in reducing error, I chose to reduce the error in the machines. Myself, the effort is worth it, its a solid base to start each project from.

View bowedcurly's profile

bowedcurly

478 posts in 326 days


#6 posted 127 days ago

you can get phenolic 48 in straight edge on ebay for like 52.00 and Peachtree has them for about 60.00 phenolic will not bow or get bent like steel I bought the I gagging 36 in st edge also it was bowed a half mile looks like an old 36in jointer knife to me I use it to chop weeds

-- Staining killed the wood<<<<<>>>>>Dyeing gave it life

View bowedcurly's profile

bowedcurly

478 posts in 326 days


#7 posted 127 days ago

the wood will bend anyway when the temp, humidity, changes long as my wood is not bowed more than an 8th Im happy

-- Staining killed the wood<<<<<>>>>>Dyeing gave it life

View Purrmaster's profile

Purrmaster

774 posts in 690 days


#8 posted 127 days ago

I thought the “gold standard” in straight edges was Starrett? Of course, you’ll need a large amount of gold to purchase one of their straight edges…

View VillageBoy's profile

VillageBoy

62 posts in 1017 days


#9 posted 125 days ago

Thanks for all the input so far guys.

Unbob-
“A really good straight edge would be a Brown & Sharp cast iron camel back style, accurate to around .0002” in 36”. that one weighs around 50lbs.
That type of tool is for rebuilding machine tools, and other close tolerance uses.

A Starrett steel straight edge in 36” length, maybe about .001” to flat.
In my view, that would be the minimum tool for adjusting woodworking machines.
Aluminum is not known for being anything close to a straight edge.”

Per your advice, I looked into the Brown & Sharpe camelback and yes…very good, very good. But I can only find used ones online. Do they still make them? Do you know where I can buy them new anywhere?

The Pursuit of Wicked Gorgeous Lumber, A Noble Undertaking
Village Boy~

View VillageBoy's profile

VillageBoy

62 posts in 1017 days


#10 posted 125 days ago

Recent results on the jointer showing the slight snipe at the front of the cut

The Pursuit of Wicked Gorgeous Lumber, A Noble Undertaking
Village Boy~

View Ocelot's profile

Ocelot

457 posts in 1235 days


#11 posted 125 days ago

I hate to admit it, but I lived without a straightedge for most of my life. I recently (a few months ago), bought a relatively inexpensive 38” alluminum straightedge. I’m quite pleased with it. They quote .002” overall tolerance. I got it from Garratwade.com, but they no longer stock the 38” (1m) length.

-Ocelot

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