scroll saw/ cupped wood advice

greitz · Post by **greitz** » Sat Feb 27, 2010 12:46 pm

I was practicing scroll sawing straight lines using some oak pallet wood scraps. The piece of wood was ca. 4" wide, 1/2" thick, with ca. 1/8 " cup. I had the two edges flat on the table, and was sawing with the grain. Everything was working fine until the last 1/4" of cut, when the saw blade just grabbed the wood and started slamming it up and down on the table (along with my thumb, unfortunately. No, I was stupidly not using the saw's hold-down. Thankfully nothing is broken, just soft-tissue damage.) By the time I let go, the piece of wood had just split along the last 1/4" and was in two pieces.

So, my questions:
1. Is it a big no-no to use a scroll saw on cupped wood? I should have jointed it flat first, but I figured it wasn't necessary for "just practicing".
2. Would it have been better if I had the wood's curved middle on the table, so that the two pieces "fell away" from the blade at the end of the cut?
3. Would it have helped if I had slowed the blade speed near the end of the cut?
4. I was using a #5 blade. Would a different blade be better for ripping 1/2" oak?

Thanks for the advice!

Gary

beeg · Post by **beeg** » Sat Feb 27, 2010 1:08 pm

FIRST thing is make SURE there's no nails or screws in that pallet wood.

mistystarz · Post by **mistystarz** » Sat Feb 27, 2010 3:32 pm

In my some what limited experience you have to just really put both hands on the piece and hold firmly ,I never use the hold down as i find when doing the intricate work I like to do it is in the way. Have had pieces grab and shatter.
Second I would suggest when cutting wood 1/2" in straight lines go to a #12 blade and a higher speed. You really have to hold the wood down with a lot of pressure or it will grab and go crazy.

tgiro · Post by **tgiro** » Sat Feb 27, 2010 3:47 pm

greitz wrote:I was practicing scroll sawing straight lines using some oak pallet wood scraps. The piece of wood was ca. 4" wide, 1/2" thick, with ca. 1/8 " cup. I had the two edges flat on the table, and was sawing with the grain. Everything was working fine until the last 1/4" of cut, when the saw blade just grabbed the wood and started slamming it up and down on the table (along with my thumb, unfortunately. No, I was stupidly not using the saw's hold-down. Thankfully nothing is broken, just soft-tissue damage.) By the time I let go, the piece of wood had just split along the last 1/4" and was in two pieces.

So, my questions:
1. Is it a big no-no to use a scroll saw on cupped wood? I should have jointed it flat first, but I figured it wasn't necessary for "just practicing".
2. Would it have been better if I had the wood's curved middle on the table, so that the two pieces "fell away" from the blade at the end of the cut?
3. Would it have helped if I had slowed the blade speed near the end of the cut?
4. I was using a #5 blade. Would a different blade be better for ripping 1/2" oak?

Thanks for the advice!

Gary

You can Scroll saw cupped wood, but it isn't easy. If you are beginning, you may want to stay with good flat pieces to start. The blade could have grabbed the wood for any number of reasons --

-- The cup of the wood.
-- You were putting side pressure on the blade instead of pushing the wood straight.
-- The blade tension wasn't tight enough.
-- You were pushing to hard on the wood to make the blade cut faster.
-- If you were cutting a curve, you may have twisted the blade within the kerf.

A good place to ask Scroll Saw questions - about any scroll saw - is http://www.scrollsawer.com/forum/. There are folks there from all levels of experience and are willing to answer questions from the most ignorant of us (that would be me

Good luck & keep practicing.

charlese · Post by **charlese** » Sat Feb 27, 2010 6:40 pm

greitz wrote:I was practicing scroll sawing straight lines using some oak pallet wood scraps. The piece of wood was ca. 4" wide, 1/2" thick, with ca. 1/8 " cup. I had the two edges flat on the table, and was sawing with the grain. Everything was working fine until the last 1/4" of cut, when the saw blade just grabbed the wood and started slamming it up and down on the table ...
So, my questions:
1. Is it a big no-no to use a scroll saw on cupped wood? I should have jointed it flat first, but I figured it wasn't necessary for "just practicing".
2. Would it have been better if I had the wood's curved middle on the table, so that the two pieces "fell away" from the blade at the end of the cut?
3. Would it have helped if I had slowed the blade speed near the end of the cut?
4. I was using a #5 blade. Would a different blade be better for ripping 1/2" oak?

Thanks for the advice!

Gary

Gary - This is a safety issue!!!!!

Your experience is pretty easy to explain - As the cupped wood reached the end of the rip, it could no longer hold it's cup and the high area fell enough to pinch the blade. From there the wood was pinching the sides of the blade and the teeth could no longer cut.

To answer your questions the best I can -
1) It is always a good practice for safety to only saw flat wood.
2) Yes! But this can still be risky - Probably not as much as using a table saw or band saw.
3) I don't think the blade type mattered much here.

That said, I have ripped cupped wood at times. Only when I needed the piece that was not cut off. (in order to joint it) In these limited cases, the high side of the cup was always on the table. This kind of operation is risky because you are not sure where the cutoff will go when released. It is not a good practice, and you have to be aware of the risks prior to cutting.

As said in an earlier post, I have successfully planed a thicker (5/4) piece of wood by very gently removing the top of the cup. In this case I put the concave side (only two edges) down and took VERY light cuts so not to let the planer press the board flat before cutting. Even this way such an operation is not recommended and may not work.

Finally - All cupped wood should be flattened prior to any sawing, regardless of the type of saw.

kalynzoo · Post by **kalynzoo** » Sat Feb 27, 2010 9:47 pm

Your experience is not unusual, and can be discouraging when practicing with the scrollsaw. I never use the hold-down, and have found over the years that it not only blocks my view of the pattern but I get better control using my fingers close to the blade to hold down and push into the blade. Using cupped or warped wood is very difficult. My experience is that the wood should always be in contact with the table, so if you must use sculptured wood, the wood should be maneuvered so the cut is in contact with the table. When cutting an irregular shape, like a beveled leg, I will create a support and cut through the leg and the support to maintain contact with the table.
As for blades, you will develop a feel for your favorite in time. My all purpose blade is a #5 reverse tooth. I like the #5 double tooth for thin, 1/4 in or very soft wood, but I then use clear tape on both sides of the cut to prevent tearout. For tight turns, for fret work, and for detailed work I use a #2 or a #2/0 blade. Seldom will I use a #7, #9 or #12, but I keep them in stock just in case. I used #12 to cut 1/2 exterior ply for yard silhouettes.
Even when you are just working on test cuts, using good wood will give you encouragement and help develop your skills.
Scrolling can be rewarding and relaxing, so keep at it and enjoy.

greitz · Post by **greitz** » Tue Mar 02, 2010 11:58 am

Thanks, everyone, for all of the advice and encouragement.

This has been another reminder to me that "free practice wood" is not really free, since this is costing me significant time out of the shop. Better to spend $ to get decent quality wood to practice on, or spend the time to properly prepare the stock (flatten it).

Thanks again!

Gary