>Reading the post below about Mike reminded me of something I've been meaning to ask here: I've got a 16" MM band saw, and a Timberwolf 1/4 4TPI blade, with a homeade circle cutting jig for bowl blanks. The jig works fine for smaller, thinner stuff, say four to six inches thick - but tall thick blanks, like Mike was saying, cause major binding and twisting on the blade - I usually just have to freehand on the BS with big stuff, which I don't like, b/c of what happened to Mike, or I just pick up the chainsaw. Do I need more tension on the blade? And no, I don't have a tension gauge, other than the one on the saw, which seems to be way off. Is tension even my problem? Any advice is appreciated guys, thanks.
>More tension will probably help, but also consider your guides and how they're set. Check out George Oxford's article below. I made a set and now use them instead of the ball bearing guides that came with the saw.
>That is a common problem due to blade drift which is present of all bandsaws (some less than others, of course). Doing it by hand shouldn't be such a big deal. I **ALWAYS** make it a point to position my hands in such a way that if the wood suddenly disappeared, but hands would go past the blade or be on the back side of it. I have healthy respect for the bandsaw, so I am always careful around it.
>David, I won't presume to suggest what others should do, but I have a couple of thoughts for you. I have a Laguna 16" saw, and use 1/2" blades, 3 or 4TPI, as I find them. I have found that I do better without the guides to cut larger blanks, because if I am roughing a lot of them, the blade inevitably gets a bit dull, and will begin to wander anyway. This tears the blade guides up pretty quickly. I use hardboard circle templates with a hole in the center, and lightly nail it to the top of the blank, opposite the flat side, or curved side up. This way I can reference the flat side of the blank on the saw table, which is much safer, and have a cutting guide. I try to cut outside the template, but if it gets rubbed or cut a little, it doesn't bother the function much. Using the bandsaw in this manner allows me to keep my fingers well away from the blade, and allows me to get the blank a lot closer to round, which eliminates a lot of the out of balance condition when you mount it on the lathe. Since the flat side is on the table, it makes the whole operation a lot easier, and, IMHO, a lot safer.
I think Dale Nish popularized this approach, but I learned it from Mike Mahoney.
I saw the Timberwolf demonstration at a woodworking show where they purposely don't use guides to demo their blades. I just tried it once after tearing up my second set of guides cutting wet wood, and it works pretty well. I really don't know about a 1/4 inch blade for cutting large bowl blanks. I'm sure I wouldn't be comfortable with such a small blade, due to barrelling and blade wander. The duller the blade gets, the more you'll be susceptible to these phenomena, again, IMHO.
I don't know if this is the absolute best way, but I cut a lot of blanks this way. If you have any further questions, or would like a picture, let me know and I'll have LOML take a couple and post them here.
Somewhere I have an article on making a homemade blade tensioning device. I made one and used it to mark tension marks on my saw. I may have trouble finding that article because I think it was in one the magazines that doesn't have an index.
When I'm cutting bowls I have my hands parallel to the blade or even behind and outside the blade. This way I can't possibly get a hand into the blade. When I teach classes the school requires that I am the only one allowed to use the bandsaw so I get a lot of practice.
I also use the wooden guides to get the bowls closer to round. This makes it faster for my students to get the bowl round.
>I made a bunch of circle templates out of a cardboard box incrementally from two inches out to the max my lathe can take. I just secure the template to the wood with a nail and move the wood so the cut follows the template. If I nick or really cut a template the blade doesn't suffer and hey it's just a piece of cardboard so I can make more. I keep them all together by running a nail through the middle of them and stacking them all on the same nail. I leave my guides a little loose, seems to work fine. Have fun, Guy
I went with the 1/4 band, trying to find a one-blade-does-it-all, so I could cut six and eight diameters, along with sixteen and eighteen inch stuff. I also thought the thin band would minimize any binding from the back of the blade in the curve. But it sounds like a 3/8 or 1/2 might be better, with more tension. I'll have to try the cool blocks too, or even just trying the saw without the guides for thick stuff.
Would it help to cut thick blanks out with the circle jig, but without the guides? Or just set the guides loose, with the jig? Or is a jig just really pointless for this thick stuff? I need to experiment with these ideas - thanks guys.
I didn't say George's guides are better than Cool Blocks. But they do the job well and are free.
For another, neither did David say he's using Cool Blocks, but I assumed - perhaps incorrectly - that he isn't, since I believe MM bandsaws come with bearing or Euro guides.
In any event, my basic message was that he also check that his guides are supporting his band properly. I found that setting ball bearing guides proved to be very finicky. Even when perfectly set, very little of the bearing is ever in contact with the band, and the slightest shift in axis can reduce that contact to almost nothing.
Moreover, the bearing has to be placed behind the set of the teeth plus the distance to the back thrust bearing which also reduces support. With a 2 TPI hook band, the set of the teeth is aggressive, and the gullets quite deep. My bands also tended to twist when cutting big rounds. As I'm sure you know, Cool Blocks, whether commercial or DIY, can support the full width of the band.
>With the bandsaw running, use a stone CAREFULLY to round the back edges of the band you use for cutting curves or circles. That reduces drag and binding considerably on tighter radii cuts.
Also, I think most of use 1/2" 3 tpi hook bands for cutting rounds. I also found that using the slightly thicker "Furniture" bands helps avoid twisting. The cost difference is marginal.
Finally, once a band has been used to cut a curve or circle, the teeth take on a set that makes it more difficult to use for straight cuts. SO, mark your bands for whichever use and don't interchange them.
>Everything I know about blade tension and guide blocks:
1 - The guage on the saw frame is not accurate.
2 - The proper tension the lowest where the band will run without vibration. A simple way to do this is to back the guides out of the way and tighted the tension knob until the band runs in s straight vertical line without any vibration. Then crank in 1/2 turn more and you are close.
3 - 12,500 PSI is a good tension to have in a bandsaw blade. The esaiest way to check this is by sound. At that tension, regardless of blade width or thickness, the tone will be a low (below bass clef) E-flat tone. This tension gauge is free, always there, and more accurate than any mechanical device.
4 - However the tension is set, the ability of the band to run without vibration in the wood is more important than running free in space. Always check the saw cut in a piece of wood. If there are ripples at 45-degrees, the blade is vibrating.
If the blade is NOT cutting straight (has a tendency to wander) and shows vibration, the tension is not high enough. Crank in more tension, 1/2 turn at a time, until the vibration ripples disappear.
If the blade is cutting OK and there is vibration, the tension could be too high and should be reduced until it makes a cut without the diagonal ripples.
If neither works, the blade could be a bad one or there is vibration in the saw from another source.
5 - Cool Blocks are an effective guide block, BUT they are slightly abrasive. Many of us bury the teeth of a fine-toothed band between the guide blocks for greater control. The abrasiveness of the Cool-Blocks will wear out the blade faster than sawing the wood.
6 - Hard Maple guide blocks that have been saturated in Mineral Oil are just as effective as CoolBlocks, they wear as well, they are less expensive, and they are NOT abrasive. Those are reasons enough for me.
7 - We should consider NOT using guide blocks when sawing a 12" thick cut to rough out a bowl blamk on a 14" saw with a riser block for several reasons. The top guide is so close to the tangent point of the wheel that it relatively ineffective. The unsupported length between the guides is so great that the guides cannot provide any control of the thin band in the space between them. Accuracy is not required for sawing rough bowl blanks.
It might be better to remove the guides, crank in one (1) full turn on the tension knob and try it. There are a lot of detractors of this sawing without guides, but I have yet to meet one of them who has actully tried doing it.
>I agree Russ, the guides are not needed IF you have a good blade and plenty of "Set" in the teeth. Cutting circles needs more set than cutting straight lines. The big thing though that needs mentioned again is sawing endgrain; bandsaws were not designed to do this and I think turners are probably the only ones who use a bandsaw to do this. I do not know of any blade manufacturer that has a blade suitable for endgrain. I do not do a lot of endgrain turning that requires bandsawing before going to the lathe so maybe someone who does this a lot can post their opinions?
>When resawing you are normally sawing across growth rings...not between them. The problem is when you are sawing in a manner where you do not cross growth rings. Each time you cross a growth ring the chip breaks but when you saw along a growth ring the chip does not break and you end up with a long shaving that does not break so it jams the blade. Try ripping with a chainsaw and you will see what I mean. Even a slight angle with your chainsaw will cure this problem. With a bandsaw, if you are sawing an endgrain blank with the heart in the center you are asking for trouble. A blank cut from endgrain to one side of the heart is another matter because you are then crossing growth rings. Does this make sense to anyone?
>I believe TD's description of "sawing endgrain" is somewhat confusing- he is actually sawing grain lengthwise. The endgrain it at top and bottom of the blank- flat against the table. Sawing the long grain is what chokes the cut by filling the kerf with long slices of wood, just as it does with the chainsaw.
I use Timberwolf blades, get them direct from Suffolk, they have instructions for setting the tension for their blades. These blades are made to be run with minimal tension; their instructions are to (first remove blade guard, back stops and guides) loosen the tension so the blade "wiggles" and keep tightening until it runs true and that's the right tension for that blade.
I use the 1/4" 4 tpi for just about everything; even logs up to 6 1/2" thick. I like it because it cuts circles with no difficulty. Suffolk also has a 3/8" x 3 tpi which is for green logs. I bought one last year, it scared me, I sent it back. When I placed my last order, the rep asked if I wanted to try it again and I agreed. I Love that blade! You just have to get over the fear as it grabs the wood........... : )
>David. My experience using a jig on thick green blanks was that it's critical to get a perfect alignment of the pivot point perpendicular to the cutting edge of the teeth. The second problem I had was as the blade got a little loaded with wet fiber and/or a little dull, it didn't want to track so well and would force it's way toward or away from the cutting arc dictated by the pivot point which doesn't move. That made cutting a continuous circle almost impossible. I think using the circle templates sounds like a better alternative than a jig since you would be able to adjust the direction of the cut as you go.