rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Mar 25, 2014 19:49:39 GMT -5
Hi, all - I've read here a number of times, now, that a person having problems with saw blade wobble has over-tightened the nut holding the blade onto the arbor. Every blade I've bought (4) has wobbled when I first installed it to the saw. My last one, I straightened out (or maybe just didn't over tighten when I reinstalled it?) after reading an article about blade re-tensioning/straightening in a woodwork forum. I, later, ruined that blade by using the wrong dressing stick to "sharpen it".
Anyhow, so I got a new blade - 14" Covington "Black" - and it wobbles and leaves saw marks just like all the other blades I've tried. Bearings are almost new - I built the saw 1 year ago and probably average maybe 3 slabs per day because some days I can't make up my mind what to cut next. Now, I've heard noise about Covington blades and how the MK303 ones are vastly superior and all that, but I can't believe that I'd go oh-for-four as far as getting a straight blade. So, either I'm super unlucky or there's something else going on, ya reckon?
The arbor I used in building my saw is a brand new Lortone saw arbor and flange. I use a 10" crescent wrench to tighten the nut while holding onto the drive pulley. I don't push exceptionally hard and really can't because I am, basically, pushing against my own left hand on the pulley. And so, my question is, How tight do you tighten the nut? Is a tight "finger tight" enough to keep the blade from slipping? Thanks, Rick
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RickN
noticing nice landscape pebbles
Member since November 2011
Posts: 85
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Post by RickN on Mar 25, 2014 20:40:49 GMT -5
lets say snug just past finger tight but before the grunt.
RickN
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,466
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Post by Sabre52 on Mar 25, 2014 22:12:30 GMT -5
Yep, just barely snug if you use a wrench. And make sure there's mo detritus under the flange. Are you sure they sent the proper flange size for a 14" blade. I used to have a horrible time with wobble on my 20" saw and found out it had come with a flange size a full three inches too small when I talked to the HP people. Installed a larger flange and the wobble totally stopped......Mel
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Post by Rockoonz on Mar 25, 2014 22:55:22 GMT -5
Flange diameter s/b one sixth the diameter of the blade so for your 14 it s/b 2 1/2. More is OK.
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rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Mar 25, 2014 23:55:02 GMT -5
Ah, so I HAVE been over-tightening! It just didn't seem like finger - with grunting - tight would be enough to stop the blade from slipping. So now I know. Thanks a TON, y'all!
Yes, I'm pretty sure I have the right flange. The description of the arbor said it was for a 14" Lortone saw. C-ya, Rick
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Post by phil on Mar 26, 2014 12:24:23 GMT -5
If you use one, make sure it s also seated properly on the bushing. If not on right could make the blade crooked and wobble.
tightening should be to just where the blade doesn't move when you hold the shaft. Anything past that will cause problems.
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bsky4463
fully equipped rock polisher
Member since September 2013
Posts: 1,696
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Post by bsky4463 on Mar 26, 2014 16:09:48 GMT -5
Seating the blade is key as Phil stated. I boned that on my 10" when I first got started and warped a blade.... Snug tight is all it will need. Cheers
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rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Mar 27, 2014 3:08:56 GMT -5
Well, I tried finger tight with some grunting but the blade slipped, so I used a wrench and just turned it maybe a quarter turn more just 'til the blade stayed in place. Thanks, Rick
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Post by phil on Mar 27, 2014 11:29:44 GMT -5
Well, I tried finger tight with some grunting but the blade slipped, so I used a wrench and just turned it maybe a quarter turn more just 'til the blade stayed in place. Thanks, Rick Sounds about right. No problems now?
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rykk
spending too much on rocks
Member since September 2011
Posts: 428
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Post by rykk on Mar 27, 2014 22:18:59 GMT -5
It improved, but the blade, itself, has some definite twists and soft spots I need to hammer out. I know perfection is pretty much an unrealistic expectation - except maybe for NASA spacecraft - but, just how much wiggling around is normal for a "good" blade? I'm shooting for just barely perceptible, but am I, maybe, being too picky? Rick
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Post by phil on Mar 28, 2014 11:49:50 GMT -5
Possibly. Some blades run nice and true, some have a little wiggle after use. Cut just one rock off kilter and you will always have some wiggle in that blade. Try a new bushing yet? Also, try cleaning the shaft where the blade sits and the mating surface of the washers, both sides of both sides. Bearings mounted with no slop? Shaft doesn't wiggle a little? Those bolts you should tighten well. How tight do you have the belt installed? Tight? Shouldn't be tight tight, just kinda barely snug. You can pull the bearings and shaft out of kilter if the belt is always pulling on the shaft instead of just rotating it. Should be no "pull" pressure there. Also very hard on the motor is it's tight. You'll wear out the motor bearings faster than normal that way. Are you dead sure the arbor is aligned properly? You've checked the front to back alignment? Changing out the arbor bearings is always more work than most people think. There are a lot of parts that need to be properly aligned or you end up with binding cuts, wiggly blades, warped blades, crooked cuts, and blades that wear out prematurely. Is the paint on the blade gone from one side but not the other? Is the wear equal on both sides? Lots to fine tune, but once done, it should run sweetly again. An improperly remounted arbor/bearings can really mess things up.
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Post by Rockoonz on Mar 29, 2014 16:38:50 GMT -5
rykk , Easy way to check runout is to clamp an old dop stick in the vice during oil change when the sump is empty. Turn the blade and run the crossfeed in so the stick barely touches the blade at the closest point about half an inch from the edge of the blade, then rotate the blade till you see the widest gap. Ideally the gap will be less than half the thickness of the blade, but I'm not going to toss it or attempt to straighten it till it is clearly more than the blade thickness. Cupping is a whole different story, if the blade begins to cup you need to find out why and fix it because the more cupped a blade gets the faster it will continue to cup.
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