Friday, 8 September 2017

How-To’s for all Band Saw Blades


The most obvious piece of information you need to know is “how long is my blade?” you need to choose the width of blade. Always use the widest blade possible – it is stronger and will withstand greater feed pressures without flexing. Blade width is measured from the tips of the teeth to the back edge
of the blade as shown above. The instructions for the particular
machine being used should be followed when selecting blade width.

How To Choose The Correct Number Of Teeth Per Inch (TPI)

If you are a woodturner, cutting bowl blanks with a bandsaw is both safe and effective. However, you will need to choose a blade that will cut the radius you need.

The minimum radius of curve for each blade width is as follows:

Blade width – Minimum radius
13mm (1/2″) – 63mm (2 1/2″)
10mm (3/8″) – 27mm (1 1/16″)
6mm (1/4″) – 19mm (3/4″)
5mm (3/16″) – 13mm (1/2″)
3mm (1/8″) – 10mm (3/8″)

When Selecting TPI remember:
• More TPI give a smoother but slower cut
• Fewer TPI allow a faster cut with a slightly
rougher finish
• At least three teeth must be in the workpiece—
the chart to the right will help you decide.

Installing your Band Saw Blade
1. Unplug the saw, then loosen the tension on the upper wheel. With all the blade guides backed off, slip the new blade around the wheels and then tension it.
2. When you have tensioned the blade enough to keep it on the wheels, track it by turning the upper wheel with one hand while adjusting the tilt of the wheel's axis with
the other hand. The blade should ride in the middle of the rim. Never track the blade with the motor running and the cover open.
3. Next, adjust the blade guides; first the thrust bearings: upper and lower, then the left had side guides.
4. Use a square to make sure you are not pushing the blade out of line and place a piece of white paper between the blade guide and the blade to allow for clearance.
5. Premature Blade Breakage
• Thickness of blade too heavy for diameter
of wheels and speed of machine
• Increase or decrease velocity
•Check wheels for defects
• Teeth too coarse for workpiece –use a finer pitch
•Decrease blade tension
•Decrease feeding force
•Brittle weld – increase annealing period, decreasing heat gradually
•Check for proper adjustment of band guides, saw guides, saw guide inserts.
and back-up bearings.
6. Blade Making Belly-Shaped Cuts
• Increase tension.
•Adjust guides closer to workpiece.
• Teeth too fine – use a coarse pitch.
•Decrease feed force. • Teeth dull.
7. Tooth Strippage
• Teeth too coarse for workpiece.
•Material not securely held.
• Too much feed pressure –reduce for good chip curl.
•Band velocity too low – increase speed.
8. Band Develops a Negative Camber
•Band is riding on saw guide backup bearing too
heavily. Adjust band for alignment on top
and bottom wheels.
•Check band wheel alignment.
9. Blade Not Running True Against Saw Guide Backup Bearing
• If clicking noise against saw guide backup bearing,
remove burr on band.
•Check band wheel alignment.
•Check saw guide backup bearing for wear, replace if necessary
•Weld not in proper alignment. Reweld blade straight and true.
10. Cutting Rate Too Slow
• Increase band velocity. •Increase feed pressure.
•Use a coarser pitch.
11. Blade Leading In Cut
•Reduce feed pressure or rate.
•Check adjustments and wear of saw guides or rollers.
• Lack of band tension.
• Tooth set damage.
12. Premature Loss of Set
• Improper width selection - check chart for correct width for radius cutting.
•Reduce band velocity.
13. Band Develops Positive Camber
•Decrease force.
•Use a coarser pitch to increase tooth penetration.
•Adjust saw guides closer to work.
14. Band Develops Twist
•Wrong width for radius being cut – choose a narrower blade.
•Binding in cut – decrease feed pressure.
•Decrease band tension.
•Adjust saw guides further from workpiece.
15. Finished Cut Surface Too Rough
• Improper tooth selection – choose a finer pitch.
• Increase band velocity.
•Decrease feed rate.
16. Band Scoring (side wear or grooving)
•Check for wear on saw guide inserts.
• Too much pressure on saw guide inserts.
•Check alignment of saw guides – be sure they are
square to front vise. Replace or clean guides.
17. Burring or Mushrooming of Blade Back Edge
• Increase tension and adjust guides.
•Check contact between blade and back edge rollers.
•Reduce feed pressure.
•Use coarser pitch blade.
•Use finishing stone.

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