so im thinking that my jointer beds are not coplaner because my edges keep coming out like big spring joints essentially, so i need something to check the beds for flatness. do i need to buy a 300 dollar starrett straight edge or does anyone get away with 50 dollar “flat stock?” the starrett customer service guy scoffed at the idea of using flat stock as a reference surface and said i need the straight edge, any suggestions?
Discussion Forum
Get It All!
UNLIMITED Membership is like taking a master class in woodworking for less than $10 a month.
Start Your Free TrialCategories
Discussion Forum
Digital Plans Library
Member exclusive! – Plans for everyone – from beginners to experts – right at your fingertips.
Highlights
-
Shape Your Skills
when you sign up for our emails
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. -
Shop Talk Live Podcast -
Our favorite articles and videos -
E-Learning Courses from Fine Woodworking
-
-
Replies
I would start by checking to make sure than your outfeed table is at the correct height. If you want a straight edge when jointing a board, the outfeed table should be adjusted so that it is a the same height as the knife edges at the top of their arc. Of course, this should be true at all points along the knife edges. So, you should also make sure your knives are at a consistent height. If your outfeed table is too high, the result of a jointing pass will be a slightly convex edge. If the table is too low, the result will be slightly concave.
What he said.
My outfeed table is set such that turning the blades by hand will move a ruler on edge about an 1/8 inch , so the blade is ever so slightly proud of the outfeed table which is what Matt wajda recommended in his video workshop on the topic, but I do get about an inch long section of snipe about 1/16 deep at the end of the board, not sure if that means anything
One inch long snipe at the end probably corresponds to the end of the board leaving the infeed table. I suspect your out feed table is not parallel and raises the plank the board as it is fed.
If the out feed table is too high, stock will not feed. You still require to check for co-planarity, I do it with a square aluminum extrusion .
Snipe at the trailing edge results from the knife too high (or outfeed table too low, take your pick). Leading edge snipe is caused by a low knife.
I set up my jointer using the 50" straight edge from Taytools. Cost about $50 from amazon and did the trick just fine.
https://www.amazon.com/Anodized-Aluminum-Straight-Guaranteed-Within/dp/B017CGDO4S/ref=sr_1_17?keywords=straight+edge&qid=1638383694&sr=8-17
Assuming you have a membership to FineWoodworking, their is a great article by John White where he makes shop made test bars to check each individual table's flatness and subsequently set both tables co-planer. I used these, 'poor man's straight edges' and had excellent results.
https://www.finewoodworking.com/2000/06/01/jointer-tune-up
Damn that is a really cool article thanks !
John White wrote a book which is my machine setup bible. It explains the process somewhat better, (for example there are two sets of test bars needed, one the length of an individual table and the other the length of the entire jointer). The book seems to be available only as a PDF from Taunton now. If you look around you may find a paper copy.
https://www.tauntonstore.com/care-and-repair-of-shop-machines-john-white-ebook-077952?search=john%20white&description=1
So there seem to be 2 things in your question. First If you haven't I'd watch the video workshop fine woodworking did on machine setup, in particular the planer. That should give you an idea of what needs to be fixed.
Now your question is almost like asking to I need a Rolls Royce to take the kids to school or can I use a bicycle. There are a lot of options in between. (But of course the Starrett guy says you need a Starrett)
Good references are important, but you also need to understand the tolerances you are working to. In building a deck I'll use a piece of bar stock (I like it better than flat as it will stand up and I can put a magnetic level on it) as a straight edge, not good enough for furniture for me. I've mostly been using rulers or the blade of my combo square for machine setup but a ground strait edge is in my future.
I like to set my tools about one order of magnitude more precise than the work I produce, so I don't need something with Starrett level precision, as my work is just not going to be that good. I'd look at something in the $50-$150 range, but something sold as a reference not just flat bar.
Snipe at the end is a sign of your blades being set higher than the outfeed table. The board is not actually in contact with the leading edge of the outfeed table, and when the end of the board leaves the edge of the infeed table, the board drops down to make contact with the outfeed table, deepening the cut for the last inch or so. I would get the outfeed table set to the same height as the cutting circle of the blades, and see if that cures your problem.
When doing this, I have run into a problem if the blades are not newly sharpened. If they are a bit dull, they will not catch and move a steel rule/straight edge, but will slide over it, giving you the impression that the table is the right height. Make sure the ruler is not lifting and dropping as you rotate the cutter. I used a straight stick of wood instead, which seemed to work better. Of course, sharp is better than "a bit dull".
I think that the people that recommend that you set the outfeed table a bit lower than the cutting circle are thinking that the surface of the wood as it leaves the cutter is a bit scalloped, so the outfeed table should be set at the height of the ridges of the scallops, which is a bit lower than the deepest part of the arc. However, unless your feed rate is really fast, the difference in height between the two would be measured in ten-thousandths of an inch, which is insignificant. Another way to check for correct outfeed table height is to start with a fairly straight piece of wood, push it thru the cutter until about an inch is over the outfeed table, turn off the jointer, and press down on the end. If there is any movement downward, the outfeed table is too low. (If you try this and you feel the board rise up as it starts over the outfeed table, and the cut is suddenly shallower, you know the outfeed table is too high.)
In the old days, when folks made their own straight edges, they made three. If all three fit tightly against each other, they all were straight.
The old days straightedge thing sounds interesting. I've been at this a long time and "3 straightedges" is new for me.
If still without a straightedge, raise the infeed table to the same level as the out feed and lay a string between the two ends of the tables.
Even better, use blocks of identical thickness at each end of the jointer under the string, and check the space in the middle with a third block.
The three straight edges idea is that two straight edges can have mirror image curves, but if a third is tight to both of them, then all three are straight.
There's a particular technical term for that process, but it eludes me now.
The idea is similar to what White does although I believe it would be more difficult to accomplish.
https://cdn.woodsmith.com/files/issues/183/creating-a-straightedge.pdf
This forum post is now archived. Commenting has been disabled