Italian Bandsaw Restoration and Blade Tracking

[Brian Rowland]

I've recently purchased a used Italian SIPA 600 bandsaw (24inch) which is similar to the well regarded Meber 600 having been underwhelmed with a JET 18X-3 which I have owned for a couple of years. The JET had a faulty motor from new and bearing guide flex limits precision.

The SIPA is not well known in the US but shares all of the good characteristics of Italian saws: strong frame and massive tensioning system, European guides and a very smooth running Italian Seimec 3hp motor. The table is huge and with strong ribbed construction. I'll post some photos of the restoration project shortly !

The machine was purchased in a somewhat un-loved state for A$800 on eBay something of a bargain and has responded well to about 20 hours of carefully stripping and cleaning everything. The European flat disc blade guides have been re-surfaced and the only obvious fault was the motor was a bit noisy - traced to dry bearings. Two stock 6206 bearings and with a couple of nights work, the motor was restored to new condition. It now runs smooth and quiet and explains why people prefer 3 phase motors!

Wheel bearings were in excellent order but the wheel rubber while not worn was impregnated with aluminium particles I have spent quite a few hours removing the imbedded aluminium and re-surfacing the rubber. I have carefully followed the instructions in the Mark Duginske bandsaw book. Wheel runout (both wheels) is now under 0.01 inch over 24 inches dia and the profile is as new - slightly crowned. Both wheel are well balanced and supported on dual bearings an a 30mm shaft.

Here's my problem: On the blade that came with the saw - a fine pitch 3/4 blade blade tracking appears fine - allowing normal adjustment of the guides. But with my newly purchased 1/2" Bi-Metal 4tpi new blade I notice a serious blade "wobble" issue which makes accurate guide alignment near impossible.

The "wobble" is about 0.050inch. When viewed from the front the blade moves laterally. The weld looks fine and the same characteristic occurs on the two blades I have purchased.

I cannot fathom out why the original blade runs true but the new bi-metal blades wobble. I have read that bi-metal blades can suffer from "vibration".

I'd be interested in hearing if others have experienced this problem with bi metal blades.

[Charles Wintle]

is it possible the new 1/2 inch bimetal blades are under tensioned?

[Brian Rowland]

Originally Posted by Charles Wintle

is it possible the new 1/2 inch bimetal blades are under tensioned?

Hi Charles, thanks for the thought...... I should have mentioned that I have tried all tensions and this does not seem to make any difference.

[Myk Rian]

Do you use the flutter method to tension the blade? It works the best for me.
http://www.woodmagazine.com/woodwork...lutter-method/

[george wilson]

3 phase motors ARE much smoother. They get 3 impulses per rev,compared to 1 for 1 phase. This really does show up on things like metal lathes. The 3 phase units produce smoother finishes on the work.

[Rick Fisher]

My gut feeling is that its the blade.. Even if it looks fine..

I had a poorly welded Lennox Tri-Master once.. It was easy to see the bad weld, and the symptoms where the same..

You should post a pic of your saw..

[William Falberg]

Brian; Do the new blades have more set than the old one? And: are the wheels spherically crowned, or "slightly" crowned? I ask because you might be "edging" up an under-crowned wheel.

[Frank Drew]

Brian, with the motor off, spin the upper wheel by hand while holding a pencil on the saw table with the point almost touching the side of the blade; slowly advance the pencil until it contacts the moving blade -- if the blade if moving laterally you'll leave a mark where the bad spot is. I wouldn't be surprised if it is at the weld.

[Paul Atkins]

Sounds like the blade. I silver solder my blades (unless I find them on Ebay the right length) and a lousy joint will foul up the works. (How's that for eloquence ? ) Anyway, blades are a consumable item with band saws and every one will be different is some slight way. I change a blade every 2 to 8 hours depending on usage and have to check each one out. I've taken a new store welded blade and cut it and soldered it because it wasn't welded straight.

[Brian Rowland]

Originally Posted by Paul Atkins

Sounds like the blade. I silver solder my blades (unless I find them on Ebay the right length) and a lousy joint will foul up the works. (How's that for eloquence ? ) Anyway, blades are a consumable item with band saws and every one will be different is some slight way. I change a blade every 2 to 8 hours depending on usage and have to check each one out. I've taken a new store welded blade and cut it and soldered it because it wasn't welded straight.

I suspect this could be the issue!

Originally Posted by Frank Drew

Brian, with the motor off, spin the upper wheel by hand while holding a pencil on the saw table with the point almost touching the side of the blade; slowly advance the pencil until it contacts the moving blade -- if the blade if moving laterally you'll leave a mark where the bad spot is. I wouldn't be surprised if it is at the weld.

I have a phase converter so I can run the machine VERY slowly the blade when viewed from the fron seems to yaw from left to right - it does not move much front to back. I estimate the yaw deflection to be about 0.040 inch....... making guide setting impossible for accurate cuts

Originally Posted by William Falberg

Brian; Do the new blades have more set than the old one? And: are the wheels spherically crowned, or "slightly" crowned? I ask because you might be "edging" up an under-crowned wheel.

BLade is hook patter 4 tpi totally different from the original blade - the original is fine toothed for aluminium and wavy pattern. The wheels are slightly crowned.

Thanks to everyone for the helpful feedback so far........ and the consensus seems to be the blade alignment with the weld.

I find this puzzling because the same blade from the same supplier runs perfectly true in my JET 18X-3!!! This is an exceptional blade for re-sawing hence my purchase for the SIPA and at 70 bucks each I'm a tad disappointed.

've spent the afternoon doing some further measurements and making a jig to do a better job of dressing the tires as I wanted to eliminate runout and eccentricity issues for peace of mind.

Heres some pictures: Note:I have removed the upper axle from the bandsaw and its mount to support the wheel with "no Play". THis is mounted to a sliding table for adjustment and i have made a rubbing block to dimension and profile the wheel.

So far everything looks pretty good with runout under 0.01 inch and typically 0.005 inch.

I'll try again tomorrow and order a new blade or two

[William Falberg]

Brian; I'm doubting your normally reliable blade supplier messed up three blades and suspecting the new blades don't interact with the wheel rims in a same way as your original blade. Are the newer blades different in set, width, or thickness? I can't see the profile very well in those pics but the wheels look a little under-crowned. Also, is that a rut I see just off-center in the tire?
By spherical crowning, I mean: Is the radius of the crown exactly equal to the radius of the wheel?
Thusly?:

http://i282.photobucket.com/albums/k...awco/ISTS2.jpg

Also: Those tire-retaining ridges on either side of the tire look to be "proud" of the tires themselves; are they rolling across the blade at any point in the blade-change or adjustment process?

[george wilson]

When I taught shop,and had no budget for a blade welder,I filed bandsaw blades in a scarf joint,and silver soldered them. The soldered joints were more boy proof than the welded joints. I made up a little jig of wood to hold the blades in alignment,and kept the torch away from the wooden jig.

[Charles Wintle]

i also thought that if the tires are fairly hard and with a wide kerfed blade rolling around the wheel, as it leaves the upper wheels edge toward the table maybe the wider tooth is causing the blade to move laterally. If the kerf of the blade did not contact the tire....?

PS This is post #800 for me.

[Brian Rowland]

Originally Posted by William Falberg

Brian; I'm doubting your normally reliable blade supplier messed up three blades and suspecting the new blades don't interact with the wheel rims in a same way as your original blade. Are the newer blades different in set, width, or thickness? I can't see the profile very well in those pics but the wheels look a little under-crowned. Also, is that a rut I see just off-center in the tire?
By spherical crowning, I mean: Is the radius of the crown exactly equal to the radius of the wheel?
Thusly?:

http://i282.photobucket.com/albums/k...awco/ISTS2.jpg

Also: Those tire-retaining ridges on either side of the tire look to be "proud" of the tires themselves; are they rolling across the blade at any point in the blade-change or adjustment process?

Hi William - thanks for your comment and advice re wheel runout/profile being the culprit . This is my gut feeling also even though I'd prefer the new blades to be the problem!. The 2 blades giving problems are bimetal 1/2inch and 4 tpi fairly thin kerf. The original blade is 3/4inch fine tooth blade for aluminium - it runs perfectly true but is thicker and wider. See photos first the aluminium cutting blade 2nd the bi metal blade causing headaches.

The fact is this is a 20 year old saw that has done some real work and cutting aluminium without a brush on the lower wheel aluminium particles must have taken their toll.

Having said that here's the answer to your question: The wheel profile is very close to speherical crowning as I estimate the radius of the tire profile 300mm. The are no ruts and there is plenty of rubber to work with see photo 3. The wheels are aluminium the edge of the tire rubber is clearly visible and about 3/16" thick and overpainted on the edge in green. The tire and sits against the shoulder of the wheel for alignment. It is well proud of the shoulder ..... perhaps not clear in the photo.

The jig I made as shown in the previous photo above was built using some scrap 18mm plywood from a 620mm table I made. When I checked the circular scrap waste against the tire profile it was almost perfect. The jig is actually 36mm wide to accept sand paper of 100 grit glued to the curved face. THere is a pivot in the jig and a wedge sytem to enable accurate mating of the jig to the wheel profile.

I have spent several hours carefully honing the wheels by hand making sure that the tire has the correct profile with a proper crown and absolutely no ridges. They now visually look pretty good and measure good BUT NO IMPROVEMENT!! I have tried tracking the blade at various tire positions but no change. Tension does not make much difference either.

Perhaps I need to take off much more rubber???

I'd like to post a short video as this explains everything.... Because I have a 3 phase converter I can run the saw very slowly and clearly demonstrate what is happening: Maybe it's time to join Utube?

The blade has an obvious twisting action with a regular pattern ie it is not random but predictable lateral swing when viewed from thr front and occurs in the same part of the blade........ but well away from the weld.

When the machine is run at normal rpm the blade looks visually better but the blade guides must have abnormally wide clearance to avoid interference......... making precision cuts impossible.

I am close to "giving up" and ordering a new set of tires from Carter but thought I would try truing the original tires first. Installing the new tires is non trivial as I believe the old rubber tire has to be ground off due to the use of epoxy. And after installing the new rubber each wheel needs to be trued.....and I don't have a lathe!!!

[William Falberg]

"I'd like to post a short video as this explains everything.... Because I have a 3 phase converter I can run the saw very slowly and clearly demonstrate what is happening: Maybe it's time to join Utube?"

By all means. Utube is a fun and easy tool to use if you can shoot and edit video. Answers a lot of questions. If a pic is worth 1000 words.......

"The blade has an obvious twisting action with a regular pattern ie it is not random but predictable lateral swing when viewed from the front and occurs in the same part of the blade........ but well away from the weld."

Are you saying the new blades are warped? If so, go back to square 1 and start over with good steel. Narrow blades are susceptible to warpage in the shipping and handling as well as tracking operations. Don't try to flatten them in the tri-folded roll; they'll warp at the inevitable cross-over when you try to stuff them in a box (or lay a vise on them ) They need coddling. A warped blade is un-fixable so far as I know. I set them aside for destructive testing.