I am not a pro scroller, so I haven't tried all the specialty blades out there. The most popular American manufacturer of blades is Olson. They make Single tooth, Double tooth, Precision Ground Tooth (PGT)), Crown Tooth, Reverse tooth, Spiral blades, et al. I use their single tooth blades because they are the cheapest, yet give me a good reliable cut.
|Q:||What is the best type of blade to use in scrolling? |
The answer is not as easy as the question:
Those pros who scroll for a living, several hours per day, will use a variety of specialty blades for different situations. And for them it's probably worth it. Especially if they get paid for being a retailer or sponsor of those blades.
The top blade shown below is called crown tooth, and below it is a reverse tooth blade. Enter the blade you are curious about in the Search box for more details.
The above is from the best scrollsaw reference book I've seen, called The New Scroll Saw Handbook (2002) by Patrick Spielman (Sterling), who was the true father of modern scrolling. He died in the fall of 2004 after publishing 75 books on scrolling. This 350 page book covers just about everything you might want to know about scrolling. A couple of other scans from his book will be found in these notes.
A good place I've found to buy ''my'' single tooth (also called skip tooth) blades is from Wildwood Designs:
http://www.wildwooddesigns.com. They have single tooth blades for about as low a price as I've found: $1.69 per dozen or about 14¢ each. Yes, I have to buy a gross of blades, 12 packets of a dozen each, to get that price. But you can buy a variety of sizes at that price, so it's no problem.
And Wildwood is a reliable company with a wide variety of products, which means I don't have to pay shipping costs for just blades. The only thing I've found that is negative is their search engine won't discriminate very well.
Note that there will be several recommendations in these notes. I haven't been paid to be a sponsor for any product or company. If I think it will help you, I'll tell you about it here.
Note that these are 'milled' blades, and are not the best. When using them I have to adjust for blade deflection because of the manufacturing process. But the better blades, manufactured by grinding, can cost double. And many of them are much more aggressive. This can be good, but it also usually means less control. And for me, much of scrolling is accurate cutting. Search this FAQ section: 'Manufacturing Blades' for more details.
|Q:||How long can I use a blade before it needs to be replaced?|
There are several factors:
Blade dullness: If you allow the blade to get dull, you will not be able to control the direction of the cut and it may begin to cut in an arc (vertical arc, where the blade bows) or at an angle. You won't be able to steer the work to follow the pattern. If you can't follow the pattern, you may as well not use one.
I've read various statements about how long one should be able to use a blade. They usually recommend from 15 to 20 minutes, but they never state what kind of wood is being cut. And if the scroller is quick, he will cut twice as much wood in a certain time as a slow scroller.
Obviously blades will dull much more quickly cutting oak or plywood than they will scrolling in balsa (a wood used in model airplanes). The glue in plywood is very difficult to cut. One could cut balsa almost all day on the same blade. If you wait until you can't steer, it's too late. Change blades often. At 14¢ apiece, most people can afford to. And a few blades are a lot cheaper than 1 ruined project.
|Q:||Why do I need a whetstone?|
Using a Whetstone:
Many scrollers keep a whetstone near the saw. When making sharp turns we tend to pull back on the workpiece (against the back of the blade) when turning the workpiece. The back corners of the blade are sharp, and this often creates a larger hole than wanted. So the whetstone is used to round off the back corners of the blade.
When you put in a new blade just hold the stone against each blade back corner for a few seconds (with the saw running, of course). But only at the back. Those rough prongs on the front of the blade (called teeth) are supposed to be there. ;-) My daughter said I should show a Smilie in situations like this. I can't guarantee total compliance.
After learning how to relax while sawing, I can now make a turn (usually) without tension, so I don't pull on the wood so hard, and don't create those unsightly holes. I seldom need to use the whetstone now. But sometimes wish I had.
The negative about getting in the habit of rounding blades is that many times you'll be doing a fret design. A fret pattern is formed by lots of small openings, and each opening is cut by drilling a hole in it and threading the blade through the hole. Lots of sharp turns and delicate corners. You have to get the blade fully installed in the saw and with some tension, use the stone, then remove one end of the blade from the saw and feed it through the access hole in the wood.
That takes lots of extra time. Much better to learn self-control and not pull on the wood when making the turn. To do that and learn other habits of good scrolling, put your cursor over Hints & Ideas in the upper right corner. Click on the Practice Scrolling box that pops up.
Please excuse some of my attempts at keeping this whole thing light. It's supposed to be fun. And it is, or should be.
|Q:||How do I know what tension to set the blade?|
Blade tension = Musical Ear?:
Well, not really.
But at least one expert says, when you pluck the blade, the 'ting' should be about one octave above middle C. That's a very loose 'about'. It gives you a ball-park figure, which is all that's necessary.
Don't allow the blade tension to become loose. At least when learning to scroll, whenever you stop cutting and the blade is not in contact with wood, re-pluck and re-tension if necessary. You'll soon recognize a tension problem by the sound and feel while cutting.
To find out why you should keep good blade tension, load a blade and start trying to cut a pattern from a scrap piece without tightening the tension control. You will not be able to steer and follow the pattern.
If you have too much tension on the blade they will start breaking while you're cutting. If you break more than 1 per day you may have too much tension.
I've broken many a blade without a serious problem. But I've read that it can sometimes tear the wood, ruining a project. Or it can cut a finger. Usually it will only be a bother, a loss of time, and some cussing when you have to thread the new blade into that narrow cut on a curve that was once smooth and unblemished.
When you get a new blade order and use the first blade, double-check the tension for the first 5 minutes. I've had some blades come with oil on an end. This made them slip in the blade clamp. I have to fix it by tightening the clamp on a paper towel, then running a 220 strip of sandpaper a couple of times through the clamp. No, I shouldn't have to do that. Maybe I could dip the blades in paint thinner or something. I haven't tried some of those other remedies.
Of course I don't really know if oil on the blades is the problem, but it seems the most probable problem. Now that I know better, I know I'm not getting oil or wax on the blades when I clean my saw table.
Another note on tension is that larger blades need more of it. A # 7 blade may need the tension set at 3, but if you put in a # 2/0 blade, you would break it at the same setting. Note that there is no standard for tension settings. Every brand of saw is different, and if you have the saw serviced, it may come back different than it was.
|Q:||Why do I keep breaking my blades?|
If you are breaking blades often (more than about 1 per day) you may have too much tension on the blade. Or you may be feeding too fast; with too much pressure. Or you may be letting blades get too dull; not changing blades often enough. Or, if the wood is scorching, the blade is getting too hot. As you can tell, I know all the questions. Just not as many answers. Search 'tension' for more.
Blade lubrication: Sawmills and such use lubricants to aid wood cutting and pitch (wood sap) problems. For the same reasons scrollers can make good use of a lube. Some woods, such as cherry, are much more susceptible to burning than others. Lubricating your blade can help.
Using clear packaging tape on the wood is now a basic lubricant when scrolling. Some companies offer a spray lube, which I haven't tried, and I won't because of the risk of getting spray in a blade clamp. I have gotten paste wax in a clamp and couldn't keep the blade from slipping out of the clamp as soon as I started cutting. Frustration!
Olson and others sell a wax stick that's so large it looks like it will last forever. I have one and I should use it more than I do, but basically I've only used it when I've had a burning problem. Except I don't know there's a problem until after it's already burned! Too late then. But I always use packaging tape.
Use added lubrication when cutting thick wood or deep stacks stacks. Also when cutting cherry wood and cutting extra hard wood.
|Q:||What is the benefit of a reverse-tooth blade?|
Answer: To have a nice smooth bottom.
Bottom of the board, that is. <:-) Oh, please!
A reverse tooth blade has a few teeth cutting upward at the bottom of the blade. The purpose is to pretty cut way down on the fuzzies and frazzling on the bottom of the wood you are cutting.
As you can see by the diagram, the normal teeth point downward, with just a few at the bottom of the blade pointing up. A scrollsaw blade cuts on the downward stroke.
The blade must be installed in the clamps so the reverse teeth come above the saw table when the saw arm is at its highest point. The reverse teeth should be far enough above the table so at least one reverse tooth completely enters the wood.
But when cutting thinner material one also has to be careful that a reverse tooth does not come above the surface of the wood being cut. Since those teeth are cutting upwards, this adds to the probability, not just the possibility, of catching the thin wood and jerking it upwards if it is not held down firmly. In addition, if the reverse tooth (or teeth) comes above the wood you will now be frazzling the surface of your project.
In addition, if you are using a zero-clearance tabletop as described in these notes, this will change the position of the reverse teeth with respect to the wood being cut. With many saws the blade clamps will not allow the blade to be raised that extra 1/4". In that case there is no advantage to using the (more expensive) reverse tooth blades.
A zero-clearance table is one that has a very small hole for the blade, instead of the over-sized hole in your saw table. Some saws have a zero-clerance insert for the table, but most don't. If you're cutting fragile frets (for example) the blade will often pull the guts of your project down into the table blade hole.
To make your own zero-clearance table go to the search engine on the FaQ page and enter 'zero-clearance'.
|Q:||Why are spiral blades useful?|
Spiral blades cut in any direction:
There are many scrollers who swear by spiral blades. Other swear at them, I hear. Search 'type of blade' and see the third blade down in the sketch.
In effect it is round. The spiral blade is used especially for fretwork (lots of shaped holes make up the design). But you do have to learn a different way of cutting because a spiral blade cuts on all sides. It's necessary to get used to a totally different way of steering.
I found that difficult.. Also the spiral leaves lots of fuzzies on both the top and bottom of the wood, which requires considerably more finishing time.
Most importantly, the spiral blade is, in effect, a round blade, so the kerf (width of cut) it makes is something like 4 times as wide as a regular blade of the same size. So the work can't be nearly as delicate.
The limit on delicacy is not only because of the width of cut, but because there's lots more pressure, both up and down, when the blade cuts. This increases the possibility (probability?) of tearing out a portion of any delicate work.
And I do like to make some delicate things, for example the piece in the photo. That project could not be done with a spiral blade (I don't think). The scan is wrong to clearly show it, but the figure is 3-D. I can't take any credit for the work on the penny. :-)
Another problem with spiral blades is that your access hole in the workpiece has to be about 4 times as large. In many delicate patterns this is not possible.
|Q:||How do I know which size blade to use?|
Blade sizes are many:
Blade sizes range from #8/0
(I have read that this is properly pronounced as 8-aught)
increasing in size to #2/0, then #1 through #12. Those are from a very thin jeweler's blade (which is hard to see when it is held up) to a blade for cutting thicker wood or stacks. There is also a blade made by Olson that is much more coarse and it is called Thick Wood. It works much better than a #12 for cutting, for example, a 2" hard maple board.
As a blade # increases, of course the size of the blade gets wider and thicker. Also the teeth get larger and there are fewer teeth per inch. Small wood cutting blades can have over 30 TPI (teeth per inch) and the largest ones have less than 10.
You can find more info in a blade chart for Olson, the best selling American manufacturer of blades. To find it click on:
Before starting to scroll you should know that there are 3 basic methods of manufacturing blades. There have been several articles about blades in Creative Woodworks & Crafts, Scroll Saw WorkShop, The New Scroll Saw Handbook and other places. Search 'manufacturing blades'.
Choosing a blade size:
Note that for all the following, the blade can vary by 1 or 2 numbers and you will notice little difference. Blade sizes vary quite a lot between manufacturers anyway.
If the pattern involves sharp turns, choose a couple of sizes smaller. If you will be cutting straight or smoothly curving lines, you can use a blade a couple of sizes larger. There can also be some variation, depending on how hard the wood you are cutting is (the density). Also on the type of blade you are using, such as single-tooth, crown tooth, et al.
Because of all this, the following are only general guidelines.
For cutting thick hard wood
(not hardwood, as in 'from a deciduous tree', but a wood that is truly quite dense)
from 3/4" to 1-½" thick, use about a #10 blade.
For hard wood, particle board or plywood 1/2" to 3/4" thick: Use a #7 to #9 blade.
For hardwood ¼" to ½" thick: Use a #2 to #5 blade.
For soft wood
(not softwood from a needle-bearing tree)
3/4" to 2" thick: #7 to #9
For soft woods ½" to 3/4" thick: A #2 to #4 blade will do.
Soft wood ¼" to ½" thick: You can use a blade from #2/0 to #4.
I'll never understand why the lumber industry couldn't have fixed its terminology to eliminate such confusion (perhaps 500 years ago). And they still could.
Balsa is a wood used in model airplanes and has about the toughness and weight of a block of the styrofoam used for packing. Really! But it is designated a 'hardwood' because it is from a leafing tree, not from an evergreen.
Scrolling thinner wood:
If you are cutting a thin stack such as 1/4" you will want a finer blade to be able to make the detailed turns. You can go as low as #2/0 or #3/0, but a #1 would be better if the #1 is not too thick for the intricate corners. When you use smaller blades that are near their limit, you have to have the saw running faster and feed (pushing the piece into the blade) much slower. When the saw is running faster there is much less steering control in sharp corners.
As mentioned, I don't like cutting less than ¼" thick because it's so difficult to control the workpiece when making tight turns, etc. I would usually put a scrap piece under the wood so the stack is at least ¼" thick. But there are no hard and fast rules. No doubt a pro has good control in almost any situation.
I'd suggest gluing an intricate pattern to a piece of thin scrap wood and try scrolling it at low speed. Then turn your saw to max and do it again. You can make a similar comparison between cutting details in 1/2" scrap ply vs cutting in 1/8" scrap. For many hints, and to keep from getting in some bad scrolling habits, put your cursor over Hints & Ideas in the upper right hand corner of the page. Then click on the PopUp box called Practice Scrolling.
Be aware that when making sharp turns such as dead-ending, then making nearly a 180° turn, the blade leaves a hole that is nearly the width of the blade, not the thickness of it. And if we don't make the turn precisely, under total control, the hole will be even larger. So using a smaller blade will reduce the size of holes. Those holes, of course, can be unsightly in fine work.
Instead of making that 180° turn, I'd suggest backing out to where there is an intersection of another line. Make your turn there. The hole will be (comparatively) almost invisible.
There are 3 basic methods of manufacturing blades for wood cutting. I don't know about specialty blades for other things such as metal. And I don't know much more about blades for wood. But I've read that there are 3 ways to manufacture them:
Milled; Stamped,which can be called punched or notched; and Ground.
Milled blades are cut (punched) from soft steel, then heat-treated to make them hard. The process causes a burr, a rough edge, on one side of the blade. This in turn causes the blade to track slightly to one side. Thus the cut will not be in line with the centerline of the arm of the saw. This can cause disorientation when cutting because you think the blade is heading where it is not. It isn't cutting directly toward your eyes.
Blade deflection angle:
This angle, off the saw centerline, is called the deflection angle of the blade. Your saw table is probably round, therefore doesn't give you a positive line-up spot for your body, as a square table would. If you aren't lined up with where the blade is cutting you will have difficulty maintaining a true straight line, and even more problems in visualizing where to quit turning from a curve to a straight line (point of tangency). And you may not position yourself at the table exactly the same each time you start cutting.
When using a milled blade it is very helpful to determine the deflection angle of the blade, at least when you are a beginning scroller. I didn't know anything about deflection when I started and made many a mistake. Go to Hints & Ideas, as mentioned above, Click on that Practice Scrolling box and you'll find details about checking that deflection angle for yourself. And you can find out how to make it work for you.
Stamped blades are punched by machine from a sheet of hardened steel. According to the descriptions, they have more 'set' in the teeth, therefore have a wider kerf (width of cut in the wood). For me, the milled blades do have enough set in their design to give me a good smooth cut and to make sharp turns, etc. But I'm not a pro and may not know enough about scrolling to appreciate minute benefits. Perhaps the biggest advantage over a milled blade is there is no deflection angle to cope with.
Ground blades are formed by a stone-grinding wheel, starting with a flattened wire of high carbon steel. Olson calls theirs PGT (Precision Ground Tooth) blades. These are not the same as 'precision-milled blades' which Olson also has. Ground blades will track down the centerline without deflection and will last as much as 4 times longer than milled blades.
I haven't given them a fair trial, but for a good reason. I like to work on comparatively delicate and miniature pieces. And there are no PGT blades smaller than #5, so I have little use for them. I am usually cutting with #2/0 to a #4. If some company starts making the ground blades in much smaller sizes, I'll probably switch immediately. If they last 4 times as long before getting dull, they are a much less expensive blade.
However, one factor of PGT (and some other blades) is that they are much more aggressive than milled blades. An agressive blade is much more sensitive in sterring. Since I don't have the money for significant amounts of wood purchase, I'm limited to small projects. I don't do furniture.
My mini projects are usually much more delicate. II want the blades I use to be easier to control. Therefore I'll have to use Olson's milled single (skip) toothed blades. At least until I learn more.
|Q:||What is the use for a pin-end blade?|
There is (almost) no use for Pin-end blades:
Don't buy pin-end blades unless your saw is so old that's the only blade it can take. They are from a design before good blade clamps were invented. They probably won't be around long, but some very cheap saws are still made that can only use pin-end blades.
As you can see, the pin on the end of the blade on the left means that you can't do any fine detailed work because it requires a massive hole (compared to the others) to feed it through the workpiece.
|Q:||Does it matter how I store my blades?|
Yes, it does matter. Blade Storage
There are many kinds of blade storage you can buy or make. Some expensive, some just DIY from your spare parts bins. Mine (above) is just a board with inset holes for PVC pipe pieces as in the photo. I use masking tape for labeling blade sizes and types.
You don't need anything fancy, but you do need something. I have to be able to pull the blade I need, with just a glance, and almost no chance for error.
'Cause if there's a chance, I'll take it.
The pictured blade rack is on the reinforcing bracket on the legs of my saw. I shudder to think of trying to sort them if it gets knocked off.
I've read that scrolling pros choose or design blade storage to allow them to pick the proper blade and get it in the clamps within 10 or 12 seconds. That has to be important when your living depends on how much you can scroll in an hour.
I live on SS and didn't discover woodworking until I retired. I do it because it's a satisfying challenge. If I had to count the seconds to change a blade it would be a chore, a burden, instead of enjoyable. But I still have to be able to find the blade I want when I want it. So I need reliable blade storage.
And another hint for beginners:
Always store all blades the same way. I put them in my rack tubes the same way they go into my saw: tooth points down. And I've made a habit of feeling the blade (not looking at it) to see if it is right side up as I'm loading it in the clamps. Obviously I learned that by trying to scroll with the teeth pointing up quite a few times.
|Q:||What happens if I go too fast or I'm having problems?|
Speed and impatience = throwing things away.
We're using 'speed' in 2 potentially different ways here. Speed, as in doing something before you've figured out if it's the right way, is the road to failure in anything we try. There's the old, old woodworking rule, Measure twice, cut once.
And that should be adapted to every step of woodworking, not just measuring. Stop and think. Relax, 'cause you can't control your steering if you aren't at ease. Consciously plug lots of patience into your scrolling. If you can't take a few extra seconds, maybe you should try ditch-digging instead. So now let's look at the speed of the saw.
Basically, the saw should run at maximum speed (strokes per minute). The exceptions may sound like quite a few, but aren't unless you are using materials other than wood. There will be an article in here describing scrolling with other materials. You will be surprised! Search 'rock', 'bone' or 'coin' and one of these days that article will be here. I need some photo work on it.
The speed at which the saw is running is not nearly as important as the feed rate, the speed or pressure you use to push the wood into the blade. The feed rate controls the quality or smoothness of the cut.
When cutting thin wood, 1/4" or less, running the saw slower will give you much better control of steering. Most scrollers will put a backing board of scrap under thin wood (making a stack) to give better control. But slower speeds (in cutting almost any wood with the scroll saw) will degrade the fine polished face of the saw cut. Also slower speeds will increase the fuzzies and frazzle on the bottom of the board.
When cutting very hard wood (ironwood, etc.) it's necessary to run the saw slower to keep the blade cooler. You probably won't often cut wood that hard. There are, however, some woods that are very subject to burning. One of them is cherry. I haven't done enough work in cherry or other problem woods to be able to give a good answer to the problem. But use packaging tape on the wood, under your pattern, because that give blade lubrication. And slow down your saw speed. But I don't know how much.
You have to scroll plastics with a medium sized blade such as a #4 or #5 and run at a slow speed, probably 450 SPM to 900. Or less. If the saw is running faster, most likely the heat of the blade will weld the plastic back together as you cut it. But there are dozens of kinds of plastic, so that was a very general guideline. You have to experiment in scrap material. Also the PGT blades run cooler than milled blades, so you may not want to use the milled.
I shouldn't even be talking about these other materials, because they aren't generally beginner projects. But while I'm at it......... Metals, ivory, bone, antler, all will require slower speeds. For example, coins are usually cut with a #2/0 to #4 blade at about 900 SPM, and with a regular skip tooth blade! Challenging! And it requires a very good lighted magnifier.
I've often wanted to get into scrolling all the new quarter series, like cutting out the horse on the Delaware quarter. And I did one, but decided I didn't want to get quite that delicate. People shouldn't have to use a magnifying glass to appreciate what I cut. But I still think it'd be a fantastic project.
A scrollsaw is truly a variety tool. You can cut most metals, marble, brick, glass rubber, paper, seashells, on and on. Of course if you're reading this you probably already are a scroller, scrollier, scrollsawer or scrollsawyer, so why am I trying to convince you?
If the lines you've scrolled (the edges of the wood you've cut) are uneven, or are not at 90°, look for these problems:
The blade could be too loose.
Fix: Pluck it and increase the tension. Enter 'tension' in the Search box.
You may be feeding too fast; pushing the wood too hard into the blade. This will cause the blade to over-flex and bow.
Fix: Don't push so hard. Relax. Stop the feed entirely, then gradually increase pressure, and listen to the motor as you do. Don't let the motor slow down. You will very quickly find a feed pressure that feels comfortable for you and gives a clean cut. Let the blade do the work. And practice some patience. No, lots of it.
You might be feeding the wood sideways, bending the blade out of vertical.
Fix: Become aware of the direction you are feeding the wood; that is, the pressure you are putting on the wood from the side. Get in the habit, especially when cutting wood thicker than ¼", of checking whether you are feeding straight into the blade. Do this by relaxing your grip on the workpiece to see if the blade pulls it into a new position. If so, of course you have to correct your side pressure. Make it a habit to check in this manner. You will eventually (not long if you are doing quite a lot of scrolling) become subconsciously aware of pressure you are putting on side of the blade. It will become automatic to feed correctly. Many other things in scrolling will also become automatic. If you don't get into bad scrolling habits as I did.
To get back to a line.
Fix: Consciously and gently turn the project and steer back to the line. Do not push sideways against the blade, even if it seems to be the logical or automatic thing to do. Again, this will soon become something you will do correctly without having to be aware of it. When cutting a smoothly curving line, do not turn back to the line suddenly. Make it gradual, a continuation of the flowing curve. If you turn suddenly you will have lots of extra sanding to do.
The saw table surface may be uneven, especially if your saw has a table insert.
Fix: Use the zero-clearance saw table overlay as shown in these discussions. (Search: zero-clearance) Also get in the habit of sweeping off the saw table with your hand, shop cloth or brush. Small pieces will get under the wood you are cutting. Always check your workpiece before starting to cut to make sure there is no burr on the bottom of the wood from the last cut or some other tool, such as a drill press. Do this by rocking your workpiece. If it doesn't rock, it's probably OK.
Most especially, if cutting wood thicker than ¼", make sure your saw table is square with the blade. The test method is described in these notes. (Search: 90°. And if you think you don't have a degrees sign, hold down Alt and type 248 in the number keyboard)
When cutting, using your magnifying glass/light combo, with some patterns you will see pattern lines that aren't drawn smoothly.
Fix: You can scroll a smooth curve much better than I can draw one unless I'm using a computer program to draw it. Almost anyone can. But watch out, maybe the pattern is supposed to have squiggly lines.
Or if you're doing an intarsia project, you have to follow all the squiggles so you match the adjacent piece, following the squiggles when you cut that one.
You have problems steering, following the pattern lines.
Fix: You may have twisted the blade when changing blade locations in the workpiece. Using a piece of scrap, draw a straight line on it and check the direction of cut, the blade deflection, to see if it has changed. If so, put in a new blade.
|Q:||Why should I paint the blade?|
|A:||For Steering Accuracy, Paint the Blade
When you know you're going to have to cut something with fine tiny details, or in poor light, or if you have vision problems, prepare ahead. Paint your blades. If you are using a standard black & white pattern, don't use black or white paint. Fluorescent orange perhaps. But please don't spray the blade while it's in your saw. I'll get blamed.
To the right is an indication of how paint can help. The blade was painted orange. The photo doesn't properly show how much assistance the paint can give in differentiating between the black line and the black blade.
Lay the blades on a newspaper and spray the leading edge, the teeth, with a light coat. Put a piece of masking tape over the blade ends. If you get paint on the ends the clamps won't hold, not only for that blade, but for unpainted ones as well.
The paint on the 7/8" cutting area of the blade will be gone in a second or 2 just by making a cut in scrap. The contrast of the paint on the upper blade will very much increase your steering accuracy because you can see exactly where the blade is cutting.
|Q:||When would I set the blade at 90°?|
Always. Setting Your Blade at 90°
That should say "Always, unless you're doing inlay work or other intentional bevel cutting."
I've heard that some put a level on the saw table. No good because your floor may be uneven. And it makes no difference if it is. The important thing is the relationship between the blade and the table. Not that the table is level.
There is a bevel guide on your saw marked in degrees to show that your saw table is at 0°. On most saws this is not accurate enough for most jobs when cutting thicker than 1/4". That includes any stack cutting thicker than 1/4" total thickness. Even the saws designed with a 0° notch on the bevel guide may be off, as mine was, because the notch location was not properly set at the factory.
Above is my bevel scale. For much scrolling it makes little difference if the blade is not at exactly 90°. For some it is essential, for example if you are cutting jigsaw puzzles from 3/4" wood. If the table is not virtually perfect, the pieces will not slide together from both the bottom and top unless you use a blade with a wide kerf (width of blade cut). Usually you won't want to do that.
It also is an absolute necessity to have the table 'perfect' when cutting 3-D figures as designed by Diana Thompson: www.scrollsawinspirations.com.
And they are well worth checking out. Another person who has excelleent 3-D ornament patterns is John Polhemus of JP WoodWorks: www.jpwoodworks.net.
I'll repeat that I'm not compensated in any way for mentioning products or people who offer something I like. If I like it, probably many of you also will.
If you do stack cutting of intricate patterns, the bottom piece in the stack will be ruined if the blade is not cutting on the bottom at exactly the same place as it is on the top piece.
That may seem hard to believe. I'd like to have a photo in here to demonstrate, then it would be obvious. (More photos will be added, which will also enhance readability.) Instead, for now, imagine cutting a pattern in 3/4" wood, which includes the drawing of the bar of a cage.
You have cut going down the outside of the bar and fed the blade into the access hole to cut the other side. This time you are cutting going up the inside of the bar. If the saw blade is at 90° to the table, the bar you have cut will be 1/8" wide on the top of your 3/4" wood board, at the pattern. And when you look at the bottom of the board, underneath, it will also be 1/8" wide.
If your blade is at 90½°, the bar will be 1/4" (or something, depending on which way you are cutting) wide on the under side of the board. Or if the blade was at 89½° the bar won't even exist on the bottom. The slanted saw blade will have wiped it out. For more information, enter '90°' in the Search box.
Checking your saw table: Choose a 2" ± block of scrap wood with sides that are flat so it can't rock on the table. Make a shallow cut on one long face. Be sure you aren't exerting any sideways pressure.
Turn off the saw and slide the block (without turning it over) to the back of the blade.
If the blade does not fit exactly into the cut, loosen the table and adjust the tilt in the amount of 1/2 of the error you see at the top of the cut. Your magnifier light will be a big help in examining it closely. Make a new cut and recheck. Repeat until perfect, usually only 1 more try. Tighten the table securely. Now you may want to adjust your bevel guide.
With many saws the table can be easily jarred from the adjustment you just made. Don't ever use your saw table for pounding anything.
For this photo, showing the block at the back of the blade, the blade was painted red and the cut was accented with blue ink.
There are other tests, such as setting a small square against the blade, but none I've found are as accurate as the test shown above.
Some suggest a 'refinement' on this method. That is to cut a square block from a piece of scrap 3/4" board. Then take it out and check the fit of the bottom of the square (or rectangle) in the top of the hole; and vice versa. This would be a very good check if you were sure there had been zero sideways pressure on the feed. Also if it doesn't quite fit, there isn't a built-in method of telling which way to make a correction, or how far to correct it.