All,
Since tuning up my Delta 14″, using John Whites approach, resawing has been a pleasure. I notice that as I begin the cut the blade flexes back a bit (only at the brginning)and I usually take it slow in the beginning…regardless, many, if not most times, the end of the board is usually a bit thicker than the rest of the board…no big deal, needs to be planed anyway.
Yesterday, however, I cut 1 1/4″ tenons cheeks and many came out slightly bowed. I’m wondering if this is a setup (eg. blade too loose) or technique issue or just the limitations of resawing on a 14″ bandsaw?
Replies
Have you adjusted your fence to compensate for the blade drift ? Also you may have your thrust bearing set to far back.
Edited 3/4/2005 7:48 am ET by brent
Brent,
If I understand blade drift, it doesn't appear to be an issue on the rest of the board...just a bit of buldge at the beginning of the resawing activity. I've checked and re-checked the thrust bearing...as you might imagine, the flex in the blade occures about 2 or more inches below the bearing..and only with the initial inch or so into the cut...after that it appears to straighten and cuts very smoothly.
I do always check to see that both the blade and fense are parrallel to each other and the table top is perpendicular to both.
BG
What size blade are you using? A narrow blade will not have the beam strength that a wider blade does, allowing it to flex rearward (and twist as well, causing the variance in thickness). Think of the beam strength of a 1x2 as opposed to a 1x4 -- the added width dramatically increases beam strength. It sounds like you either need a wider blade or more blade tension. Experiment with the tension if you don't have a wider blade handy. The fact that your cut settles out and runs true speaks well of the tracking and cutting ability of the blade, it is just deflecting when pressure if first applied.
Woody
Woody,
I'm using a 1/2" Olson, I'll try to tighten a bit and see what happens. thanks
Actually drift can cause the exact problems you are having.Every time you change blades on your bandsaw the fence must be re-adjusted to compensate for that particular blade.Check on page 162 of White's book for the proper way to do this. Also Woody's probably correct about the tension.It's hard to get the proper tension on a 14" saw for a half inch blade, you may need to upgrade your tension spring.You also mention the flex in the blade occurs 2" above the work piece..............The guides should not be more than 1" above the cut.
Brent
Edited 3/4/2005 2:32 pm ET by brent
Brent,
He doesn't say two inches above the work, he said two inches below the blade guides. This sounds like it is in the middle of the cut, which would indicate the tension problem. I doubt that he has a blade drift issue since it quickly settles down and makes a good cut -- a blade drift would have really made a mess with the loose tension, twisting the cut badly.
Woody
Woody,
You're right about the bearing hight, I read it to fast. But about the drift ,he says his resawn boards end up thicker at one end........that is blade drift. It may settle down to a smooth cut but it's not perpendiculsr to the fence. You're right about the 2 combined making a mess of a cut, but on the other hand, bowed tenons sounds like a tension problem, and resawn boards with different thickness at the 2 ends sounds like a blade drift problem. I don't know what kind of bandsaw you have, but I have a 14" delta myself and believe me ,it's amazing the tweeking and hammering you sometimes have to do to get them cutting perfectly.Once there it's a hell of a good machine,but like a plane, it's more of a kit out of the box.
Brent
I shudder when I think of the struggles I have had with an out-of-tune machine. I tried for six months to find an older and solid Delta, finally gave up. Not very impressed with their current ones. I now have a new Grizzly that is working great, just hope it keeps it up. Loving it for now.
Anyway, regarding his problems, the wide cut he described occured only at the beginning of the cut, at the same time he saw the deflection. It then settled down and completed the cut fine is why I say it didn't sound like a drift problem. With a drift probled it would have just gotten worse. In any case I am pretty sure he needs to increase the tension on the blade. The bandsaw is a beautiful thing to use when it is purring right.
Woody
Amen to that friend.
Guys,
It's kinda fun to be talked about, thanks.
"The bandsaw is a beautiful thing to use when it is purring right"
Exactly, ergo no sudden moves..I'm only into this bandsaw thing about a year but I'm learning quickly that these puppies are ruled be unfriendly gods.
I did give the knob a turn to tighten the blade a bit. Not ready to declare victory yet but so far so good. For the 1/32" bow on the first inch or so that I'm trying to eliminate don't want to anger the creatures from the netherworld.
I find that "bowing" is usually a tension issue. Check out the tensioning instructions at Highland Hardware, obvious URL. The instructions are in the WoodSlicer area. They really help.
Charlie
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