Cutting a radius in 3" maple

[FallCreek]

I'm building a rocking chair from maple and the two rockers will be about 3" wide. The rough cut material has been drying for about 7 years and after cleaning up the various blanks I've been rough cutting the various parts on the table saw and band saw that have been as much as 2" thick. In each case cutting the material offered a great deal of resistance and produced burn marks. My table saw is a 5HP cabinet saw initially with a 80 tooth and later with a new 40 tooth that yielded somewhat better results. I'm certain the fence is parallel to the blade. My bigger issue is cutting on the band saw. I cut several curve pieces that were 2" thick using a 3/8" 3tpi brand new bimetal blade and the process was extremely slow yielded burned wood and a blade covered in resin. I switched blades to a 3/4" resaw blade with somewhat better results but now I need to cut two 38" long rockers from 3" stock and I'm concerned my 14" table saw isn't up to the task. My plan is to cut all the parts to 1/16"tolerance and clean them up with a template and flush trim router.

I would appreciate any ideas or help on how to cut 3" maple with a 69" radius over about 38" length other than or augmenting cutting it on a band saw.

Thank you

[Tom King]

It shouldn't be any problem for a well tuned bandsaw.  A 1/2" blade should be able to do it just fine.  The 3/8's should have been able to cut it, but it sounds like to me it needed more tension.

I wouldn't think about making that curved cut on a tablesaw.

[gee-dub]

I've got to think something else is going on here.  I would investigate why you are getting resin build up.  I think the answer to this may be an overall answer.  I cut 10" maple on my bandsaw with a 2-3 skip blade with good result.  A 5HP tablesaw should cut through 3" material pretty impressively although I would have selected a 20 or 24 tooth blade.  i cut 2" walnut and maple on a 3HP, 10"  saw with a 24 tooth full kerf blade without much difference from 1" material except for a slightly reduced speed. 

With the trouble being present on different machine types I would focus on the material.  Was it milled properly for cutting on the tablesaw; one flat face and one perpendicular side?  The trouble at the bandsaw is what has me stumped.  You can cut some awfully gnarly stuff at the bandsaw without issue.  The combination of resin build up and burning from the same material has me scratching my head.  I may not be picturing this clearly.

[wtnhighlander]

The thicker material needs a saw with fewer teeth. As each tooth travels a longer distance through the stock, it collects more waste in its gullet. If the gullet fills before the tooth exits the stock, the packed waste produces friction against the sides of the kerf, resulting in burn marks. The friction also heats the blade and prevents the tooth edge from cutting cleanly, resulting in more torn wood fibers that adhere to the blade as 'resin buildup'.

This is true for any saw, no matter how sharp. To make thick cuts with a higher tooth count, the only option is to reduce the feed rate, and that isn't always successful. Selecting the correct saw tooth geometry is the best way to go.

[FallCreek]

On 6/11/2022 at 7:04 AM, Tom King said:

It shouldn't be any problem for a well tuned bandsaw.  A 1/2" blade should be able to do it just fine.  The 3/8's should have been able to cut it, but it sounds like to me it needed more tension.

I wouldn't think about making that curved cut on a tablesaw.

Thanks. I only mentioned the table saw as a reference regarding burn marks when cutting rectangular blanks. I would never attempt a curve on the table saw.

[FallCreek]

On 6/11/2022 at 8:05 AM, gee-dub said:

I've got to think something else is going on here.  I would investigate why you are getting resin build up.  I think the answer to this may be an overall answer.  I cut 10" maple on my bandsaw with a 2-3 skip blade with good result.  A 5HP tablesaw should cut through 3" material pretty impressively although I would have selected a 20 or 24 tooth blade.  i cut 2" walnut and maple on a 3HP, 10"  saw with a 24 tooth full kerf blade without much difference from 1" material except for a slightly reduced speed. 

With the trouble being present on different machine types I would focus on the material.  Was it milled properly for cutting on the tablesaw; one flat face and one perpendicular side?  The trouble at the bandsaw is what has me stumped.  You can cut some awfully gnarly stuff at the bandsaw without issue.  The combination of resin build up and burning from the same material has me scratching my head.  I may not be picturing this clearly.

I appreciate the feedback. Before cutting the material on either saw I flattened and squared it on the jointer and got very good 90 degree edges. I've tuned the band saw and rechecked the table saw blade / fence adjustment. Yesterday I cut some more blanks on the table saw and pushed the material through as fast as feasible with better results but still some burn.

I agree with you. It's something odd about the maple.

[Tom King]

Some Maple is just going to get some burn marks from sawing.  I've never spent a lot of time trying to figure out how to eliminate it all.  Just allow for taking care of it in the next step.

[Mark J]

Especially if it's hard maple (aka sugar maple).  

[roscoewoodworker]

I have a 14" bandsaw and, using either a 3 or 4 TPI 1/2" blade should be appropriate. While 14" bandsaws can accomodate a 3/4" blade, I have read much on why it might not be advisable to use that wide a blade on a 14" saw, mostly related to power to drive that blade through the wood, especially hardwood. Anyway, I've never had a problem with that thickness of wood, regardless of what type of hardwood it is. My bandsaw has a 1 1/2 HP motor, which might be more than some 14" saws, but I doubt that makes that much difference. I do get some burning in harder woods cutting curves, but never a lot. 

I always thought I knew how to set a bandsaw up properly until I read and viewed a number of books and videos on the subject. Michael Fortune and Alex Snodgrass are expecially good resources; Michael Fortune especially for cutting curves (as he does a lot of that). The main things are blade tension has to be high enough, guides set up properly, blade guard close as possible to the top of the wood. With Michael Fortune, he talks a lot about how to guide wood along a line when cutting curves. If you can master that, things will improve immensely (sometimes I have it down and sometimes not).

In the end, some  burn marks aren't that much of a problem. I assume that you need to sand the bandsaw cut curve smooth anyway. The marks should come off assuming you leave enough outside you line to sand off. A better way might be to make a template of the piece, sanding it smooth to the shape you want. Rough cut the actual pieces on the bandsaw, leaving enough to routh off with the template, and then attach the pieces to the template and rout them exacdtly as you want them with a flush trim router bit. This is best done on a router table, but if you don't have one, there may be various ways to make a jig to hold the pieces while hand routing them.