Craftsman model 21400 Band Saw issues

[KMAHER]

I would first like to thank everyone of the wealth of information I have gleamed from here, by lurking here for the last 5 years. But now I have a problem, that I need some suggestions with.

I have the Craftsman 21400 band saw, and have a problem when cutting.

The cut line/ kerf of the blade will wobble or flutter and open up the cut.

If I make a cut into some stock, and let the stock sit in one place while still running the saw. The blade will open up a kerf to about 1/8" , the stock is not moving. You can see the blade move back and forth.

This has happened with the stock blade and a new Timber Wolf I ordered.

Any ideas of where to look for adjustments?
I have put my dial indicator on the top of the blade and rotated the wheels, but I don’t see very much variation except for when I hit the weld on the blade.

Thanks for any help,

kyle

[durango dude]

I'd check:
- tension symptoms like this could come from over or under-tightening.
- tires ---- check for smooth tires - especially if you've cut a lot of pine.

[Stytooner]

Tension on the blade would be the first suspect. Secondly would be the guide adjustments.

[greenacres2]

I too would check tension first, then guide blocks. I've found the Alex Snodgrass video on band saw tuning to be very helpful...
http://www.youtube.com/watch?v=wGbZqWac0jU

If the tires are only a little loose, they'll flop a lot a speed (kind of fun to watch until they fall off--i'd not encourage that though!!). Almost any slight variation will be greatly exaggerated at full operating speed.

Question for those who may know--Could a fatigued tension spring cause or contribute to this type of symptom? Seems like it would not be obvious when not running then show up at speed??

earl

[cwsmith]

A couple of things come to mind.

First and foremost is, as the others have said, check the blade tension! When the saw is turned off, that blade should should indicate tension, almost like a guitar string, though not quite as tight. As I recall, there are tension mark settings on that should give you a good indication, unless the blade is stretched.. the tension should always be relieved when the project is ended and the saw is going to be idle.

Second, check that the blade guide rollers are properly set. They shouldn't "pinch" the blade, but they should be set properly against the back portion of the blade sides... about half way between the bottom of the tooth gullet and the back edge.

Likewise, the thrust bearing used to stop the blade from being pushed back (on feeding), should be such that allows NO backward movement of the blade when feeding. (This however shouldn't be giving you the side-to-side movement that you are indicating.)

In addition to checking the tires, as others members have advised, I'd also check the how you have the upper guide arm set. I've learned to always minimize the "throat" or distance above the work piece. The upper blade guide should be lowered to allow only the minimum of clearance above the stock being fed. The idea is that the portion of the blade that is doing the cutting, should be supported with as short a distance as necessary. If the upper guide arm is left too high above the work piece, there is great movement thus sloppiness to the cut.

Lastly, and probably even more important before you start other adjustments, is to know that the upper and lower wheels are properly aligned with each other. If the blade is coming down off the upper wheel and the guides are forcing them into position there can be significant vibration and/or flex. This I would think would pose other problems as well.

I hope this helps,

CWS

[capncarl]

I noticed on one of my earlier band saws that after leaving the blade tensioned for months that the blade deformed the tires and caused the back and forth blade travel that you mentinoned. After replacing the tires the back and forth travel went away. Lesson learned, always relax the tension when not in use.
capcarl

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[Knottscott]

IIRC, the Timberwolf blades require less tension that most, so definitely check the tension and don't overdo.

[LCHIEN]

sounds like a (under) tension issue to me.

Also I always try and remove tension when not using the saw.

So look up bandsaw tensioning. And I think there's some info on the Timberwolf (suffolk machinery) website specifically giving their recommendations on tensioning methods.

[cabinetman]

A couple of things come to mind.

First and foremost is, as the others have said, check the blade tension! When the saw is turned off, that blade should should indicate tension, almost like a guitar string, though not quite as tight. As I recall, there are tension mark settings on that should give you a good indication, unless the blade is stretched.. the tension should always be relieved when the project is ended and the saw is going to be idle.

Second, check that the blade guide rollers are properly set. They shouldn't "pinch" the blade, but they should be set properly against the back portion of the blade sides... about half way between the bottom of the tooth gullet and the back edge.

Likewise, the thrust bearing used to stop the blade from being pushed back (on feeding), should be such that allows NO backward movement of the blade when feeding. (This however shouldn't be giving you the side-to-side movement that you are indicating.)

In addition to checking the tires, as others members have advised, I'd also check the how you have the upper guide arm set. I've learned to always minimize the "throat" or distance above the work piece. The upper blade guide should be lowered to allow only the minimum of clearance above the stock being fed. The idea is that the portion of the blade that is doing the cutting, should be supported with as short a distance as necessary. If the upper guide arm is left too high above the work piece, there is great movement thus sloppiness to the cut.

Lastly, and probably even more important before you start other adjustments, is to know that the upper and lower wheels are properly aligned with each other. If the blade is coming down off the upper wheel and the guides are forcing them into position there can be significant vibration and/or flex. This I would think would pose other problems as well.

I hope this helps,

CWS

+1. Check the tires for any debris under them or any damage to them. Also check the weld on the blade.

.

[LCHIEN]

Here's the excerpt from the Suffolk Machinery Timberwolf bandsaw balde vertical woodcutting bandsaw blade Six rules of sawing:



FOR TURN SCREW AND SPRING TENSIONING MACHINES
1. Remove guides–you CANNOT run this test if the band saw blade is restricted in any lateral movement.
2. Make sure tire surfaces are in good condition–they cannot be hard, flattened out, cracked or brittle. On mills with loose fitting V-belts, replace them with the next size down so they are tight fitting. This will eliminate over 80% of the vibration in your mill and the blade.
3. Mount the blade on the machine and apply the tension to the band that the manufacturer recommends for other steels.
4. Close all covers for safety purposes.
5. Start the machine, engage the clutch into the high speed cutting mode. NOTE: You will not be cutting any wood.
6. Stand at the head of the machine, with your hand on the turn screw tensioner and your eyes on the band saw blade. Very slowly start detensioning by half turns at a time, keeping your eyes on the band saw blade. The object is to bring the tension of the blade down to a point that the blade starts to flutter. TAKE YOUR TIME.
7. When you see the band start to flutter, you have hit ground “ZERO”. Now start ADDING quarter turns of tension, SLOWLY, until the band stops fluttering and is running stable again. At this point ADD one-eight to one-quarter turn of tension.
8. You have now tensioned our blade correctly. Shut off the machine and put your guides back in place. You are now ready to start sawing.
9. ALWAYS DETENSION YOUR BAND SAW BLADES. Since you do not know exactly where the proper tension is, it will be easier to remember if you take off 8, 9, or 10 full turns of tension until the band is completely relaxed. The next time you use our bands, add the same amount of turns of tension that were taken off. At this point, you will only have to run the flutter test one time.

Entire article: http://www.suffolkmachinery.com/six-...of-sawing.html

[KMAHER]

Thanks for all the suggestions. I had some time this weekend and what I found is that the blades actually jumps to the right. I can see this even at slow speeds. The blade runs true then it moves to the right, the back to center. The jump is almost 0.120", but I don't see any bumps on the tires.

Thanks for all the help so far.

Kyle

[Stytooner]

How is that possible if the guides are adjusted correctly? Sometimes the weld on blades are not perfectly flat and I do see a jump like you mention, but not that much.

[toolguy1000]

i'll bet, when all is said and done, that the problem rests with the blade (s). get a perfectly welded blade to positively remove that as a "jump causing" variable. i had 4 NIB t-wolf blades and ALL had misaligned welds. took a properly welded blade from iturra design to straighten out the problem.

[LCHIEN]

Thanks for all the suggestions. I had some time this weekend and what I found is that the blades actually jumps to the right. I can see this even at slow speeds. The blade runs true then it moves to the right, the back to center. The jump is almost 0.120", but I don't see any bumps on the tires.

Thanks for all the help so far.

Kyle

is it jumping once a blade revolution? If so, the weld is bad.

If it occurs more frequently, e.g once a wheel rotation then you have a wheel problem.

You should be able to see this rotating the wheels by hand, you might have to remove the belt to be able to do this. Be careful of the teeth.

[eezlock]

craftsman 21400 band saw issues

I agree with CW Smith about the blade guides, check above and below the
table and adjust them as necessary. You will always need some "light tension"
on the blade(side pressure) when it is rotating to keep it in proper alignment because of blade flexing. This is always a problem especially when blades are
changed. Different width blades flex differently and will cause side movement
differently. Hope this helps.....eezlock