Well here I am with my 1st post. I’m a new woodworker that has become hooked. I’ve converted my 2 car garage into my woodshop, (the inside never to see a car again!).
My question is regarding a Delta 8″ dado that I have. I’m trying to make a box joint jig. I’m using 3/8″ for the pins. This should theoretically should require an 1/8″ chipper to be inserted in the dado. When I do this and perform a test cut, I’m 1/32″ over on the cut. I can’t figure out why. I have the test piece clamped down so it’s not moving. I fiddled with the chipper setup on the saw. Is it a problem with the dado? or am I seeing a bit of runout on the tablesaw? It seems to me that the longer the joint the more error I’m going to get.
What is the best way to correct this for making the box joints? I’m thinking about using a 1/16 chipper and shiming it out to get precisely 3/8″. But I wanted to use the best method. Since I’m trying to make a jig, I want it to be setup perfectly so I can make trouble free joints.
Any replies are appreciated!
Bill
Replies
Bill, you're right, that's surprising. Most dado sets would cut exactly 3/8", or even somewhat under. I know you've examined your setup carefully, but I'd look at it again.
Your proposed solution -- using the 1/16" chipper and loads of shims to get a 3/8" dado -- probably won't work. The teeth on the outer blades are probably not wide enough to cover the shims, so you won't clear the entire dado with the dado set. The better solution is to build your jig to make 13/32" fingers and dados. That is, live with what your dado set wants to make.
My advise to you is to make the box joints 13/32" instead of the 3/8" It maybe easier to modify the wooden parts of your jig than the metal parts of your blade. Also have you tried using a different chipper blade it maybe the blade is a little off. Or you could have a problem that I used to have with my old saw, where the armature was bent and the blade would make a larger cut do to the wobble.Scott C. Frankland
Newfoundland Wood Worker
I'm going to assume your using a jig that is guided by the mitre gauge slot and not the fence. Make another test cut making a conscious effort to push the mitre guage to the right. Don't pull it back thru the blade, just shut it off and check the kerf width. If it's right-on the dado/saw are good. The bar has to fit the slot very well. Peen one side of it 3 or 4 with a prick punch to tighten it up. Your suspicions are correct the error will accumulate, the more pins the more error. The critical dimension is getting the spacing between the indexing pin and the blade to match. I prefer using the method that when I finish one piece I register the first socket on the mating piece from the 1st piece. This tends to zero the error at least up to 12" wide pieces anyway. I've tried to save time and stack two pieces but it's too hard to get the offset spot on.
John O'Connell - JKO Handcrafted Woodworking
Life is tough. It's tougher if you're stupid - John Wayne
I too have the Delta 35-535 8" stacked dado set and am also getting a slop of about 1/32" in my dadoes. I currently have the cutters stacked for 11/16", but my dial calipers is giving me a reading of almost 23/32" (actually 91/128" if you want to get super precise). Since I am getting this measurement directly from the blades (with the saw unplugged, of course), the alignment of my cabinet saw or fence does not figure to be the cause.
In the past, I have noticed the same variance with different dado widths. I suspect the culprit to be the two outside blades. Specificallly, the inside of these two blades has a raised area around the arbor hole (kind of like a built-in shim), ostensibly to keep the teeth of the outside blade clear of the teeth of the adjacent chipper. My hypothesis is that this raised area is about 1/64" too thick on each blade, thus accounting for the 1/32" overcut.
My remedy, other than getting a more accurate stacked dado set, is to stack it 1/16" shy and then shim it out to final width. In your case, insert the 1/16" chipper and one or two of the cardboard shims between the two outside blades and make a few test cuts. The three cardboard shims included in the set total over 1/16" in thickness, so your desired width is achievable, albeit with a lot of trial and error.
You could check the hypothysis by making a 1/4" test cut without any chippers. If all the error is accounted for then maybe a saw shop could joint the outside of the teeth. If the chippers are off too, then it's shims, two passes with a thinner stack or a new set. My CMT is right on the money.John O'Connell - JKO Handcrafted Woodworking
Life is tough. It's tougher if you're stupid - John Wayne
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