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Tip #31
Band Sawing Versatility (continued)
Click here for a printer friendly version of Tip-
Pg. 1-3, Pg 4-6, Pg 7-9, Pg 10-12, Pg 13-15, Pg 16-18

Basic Bandsawing

Figure 14-4. Adjust the upper blade guide so that it's a maximum of 1/4" above the workpiece.

Adjust the height of the upper blade guide so that it's no more than 1/4" above the work (Figure 14-4). Then think through the cut before you turn on the machine. Know where you'll put your hands as you feed the stock into the blade; make sure the stock won't be blocked by the bandsaw frame (Figure 14-5). When you're satisfied that you can make the cut safely and without interference, turn on the power, set the speed dial to the proper speed and wait until the machine comes up to speed.

Figure 14-5. (A) Visualize the cut before you begin and you can avoid the kind of throat interference that is occurring here. (B) Started this way, the cut can be made in one continuous pass.

Take a comfortable stance in front and slightly to the left of the blade, and start your cut. As you work, you may shift more toward the center. Warning: Stand on the left side of the blade. If the blade breaks it may fly to the right. Slowly feed the stock into the blade. Use both hands to guide the stock and keep it pressed firmly down against the table.

As you work, watch out for several problems that may cause the bandsaw to bog down or produce an inaccurate cut:

  • feeding the stock too fast
  • side pressure (against the flat of the blade)
  • trying to turn a radius too small for the blade
  • excessive blade "lead"
  • worn or dull blades.

Don't force the work, but you can feed fairly rapidly since the machine cuts quickly. It's alright to pause in the cut for a moment, but try not to remain stationary for too long. The blade will heat up in the kerf, burning both the stock and the blade. Feed the stock directly against the teeth, even when cutting curves. To determine if the blade is the right size for the curve, refer to Table 14-1.

If the blade continually wanders off the pattern, there are several possible causes: The blade guides may be improperly adjusted. Or you could be pressing against the side of the blade. You may also be trying to cut a curve that's too tight for the blade. If the blade wanders or "leads" just to one side or the other, the teeth are improperly set. To correct the set of the teeth, refer to the Bandsaw Owners Manual.

If the machine bogs down, stop a moment to let the bandsaw catch up. Check to see if the blade is twisting in the guides. If it is, you may be pressing against the side of the blade or trying to turn a corner too tight for the blade. If the guides, you're probably feeding the stock too fast. Once the bandsaw is back up to running speed, feed the stock a little slower. If the problem persists, check the blade to see if it's worn. Replace dull or worn blades immediately.

If the blade jams on a scrap, turn off the machine and unplug the power before you attempt to clear the scrap. If the blade breaks, move around to the left side of the machine and turn off the power. Wait until the wheels come to a complete stop before removing the cover and the broken blade.

Basic Techniques
Getting a smooth, accurate cut begins by guiding the stock carefully with both hands, feeding the stock forward against the teeth at the proper rate, and not turning corners too tight for the blade. Here are a few additional suggestions to help you get the best results:

Cutting Outside the Pattern Line-For precision work, cut slightly outside the line--in the waste stock--then sand to the final dimension with a disc sander, belt sander, strip sander or drum sander. Not only does this technique make it easier to be accurate, the finished edge is smoother. The mill marks left by the bandsaw are removed when you sand up to the line.

Figure 14-6. Break complicated cuts up into simple curves and lines.

Breaking Up a Cut-Break complicated cuts up into simple curves and lines. Study your pat-tern to see how you might cut it in several easy passes. Don't be afraid to cut into the waste stock and loop around in order to reposition the blade at a better angle to the pattern line (Figure 14-6).

 

 

Figure 14-7. You may have to backtract with the blade in order to cut some patterns. Plan ahead and avoid backing out of cuts.

Backtracking-In order to break up intricate patterns into simple cuts, you may have to cut in to a point, then back the blade out and cut from another angle (Figure 14-7). This is a safe technique if done carefully, but there is always a danger that you may bind the blade, pull it out of the guides and off the wheels. Sawdust can also build up behind the blade, preventing you from backing it out. To backtrack out of a cut longer than 1", turn off the machine and let it come to a complete stop before backtracking. If you can, avoid backtracking in long cuts altogether.

Click to see larger view
Figure 14-8. Round or square relief openings can facilitate making internal cuts. When possible, plan the openings as part of the design.

Drilling Relief Openings-A few well-placed relief openings will give you sufficient turning room to make tight cuts. Square-cornered relief openings can be formed with mortising bits and chisels; round holes, made with drill bits, can be used when the blade can't turn the radius required. Sometimes, corner holes are used just to make bandsaw cutting easier; the radius of the corner is exactly right because of the bit size that is used. In all cases, be sure the layout for the corners, square or round, is accurately done to conform to the design (Figure 14-8).

Figure 14-9. Relief openings give you turning room to cut tight internal corners. Click on image for larger view.

Keep in mind that making relief holes is one of the handiest techniques for cutting intricate scrollwork (Figure 14-9). Drill these holes slightly inside the pattern line in the waste stock.

Making Relief Cuts-Radial or tangential relief cuts make it possible for you to cut a curve smaller than the blade can normally turn. Make radial cuts toward the pattern line and backtrack out (Figure 14-10). Then cut the desired curve. As the blade meets up with each radial cut, a little piece of waste stock will fall away. This, in turn, provides more room for the blade to turn.

 

 

Figure 14-10. To cut tight external curves, make several radial cuts before you cut the pattern line.

 

Figure 14-11. You can aslo cut tight external curves by making a series of tangential cuts as shown.

Make tangential cuts by cutting on the pattern line until the blade starts to bind slightly, then run off at a tangent to the curve. Cut completely through the waste stock to the edge of the workpiece, removing a small amount of stock. Start cutting the pattern line again where you ran off at a tangent (Figure 14-11). Repeat this process until you've cut the desired curve.

Remember that radial cuts are useful when cutting both internal and external curves. Tangential cuts can only be used on external curves.

 

Figure 14-12. To cut corners and curves in tight spots, feed the workpiece very lightly agains the blade and let the teeth nibble away.

"Nibbling"-There are times when you'll need to cut a detail in a pattern that's too small to use any of the techniques described previously. For these extra-fine jobs, feed the stock very, lightly against the blade and let the teeth "nibble" it away (Figure 14-12). This is handy when you need to cut tiny corners and curves.

 

Figure 14-13. Wise planning of the layout can often make it possible to join pieces to form a particular shape. It is also a way to economize with material.

Layout-Many of the methods described in connection with scroll sawing and jigsawing can be used to minimize layout and waste when bandsawing. A specific application, which is typical, is the forming of acurved rail (Figure 14-13). Two pieces that result from a single cut are joined to form the arch shape.

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