Wood jumping question

[Scruffydog]

Q: Why does wood jump while cutting?

I have the blade in correctly. The feed rate is slow. The motor speed? Bad wood? Bad blade?

What have you learned about scrolling to help you overcome this? Sometimes I feel like I have to hold down the wood so hard my already arthritic hands get so sore. It cant just be my lousy saw.... Can it?

[Bill WIlson]

The wood is probably jumping because the blade is grabbing the wood, instead of cutting it.  This happens for a couple reasons.  The simplest is a dull blade or blade installed upside down.  Barring that, the most common cause is trying to make tight turns too fast.  Pushing the wood into the blade, while turning quickly and tightly doesn't allow the blade to cut fast enough and the blade will bind in the wood and the teeth will grab on the upstroke, instead of cut.

This can also happen when trying to use too large of a blade.

What size & type of blade are you using?  What kind of wood are you cutting and how thick is it?  Does the lifting happen just in cutting curves or all the time?

Many scroll saw blades have reverse teeth in them.  This is intended to reduce the tear out on the bottom  of the wood.  Most reverse tooth blades just have a few teeth pointing up at the bottom.  Some have reverse teeth placed through the entire length of the blade.  These sometimes cause more trouble with lifting the wood, because there are more reverse teeth engaged at any given time.

If the problem persists, you could try a skip tooth blade, which only has teeth that point down.  You may sacrifice the slightly cleaner cut that a reverse tooth blade offers, but it should help minimize the lifting.

  Also, most scrollers remove the hold down bracket on their saw, but if your saw is still equipped with one, make sure it's lowered far enough to help hold the wood down, without being too tight and causing friction between the wood and the table.

Good luck.  Hope this helps.

[dgman]

Bill has given you most of the reasons for your issue, except one. I have found that to slow a blade speed will cause your problem. Try speeding up the blade speed. I teach my students to start with a medium speed, then adjust from there. 

[JTTHECLOCKMAN]

Just about all points were touched in why wood jumps when cutting. Too slow of speed, to hard on pushing especially tight corners, blade type and choice, thickness of material. One other possible cause because you do not mention the saw is too aggressive setting of cutting action. Maybe the saw can be adjusted and maybe not. The old 2 speed dremels were a culprit of this. 

[munzieb]

It may be also possible that the amount of bite the blade takes may be too aggressive. Looking at the side of the blade mounted, the angle from top to bottom may not be close to perpendicular and takes too much of a bite. I have an EX-16 and by rotating the motor, this bite angle can be adjusted. I tend to use smaller skip tooth blades. Larger blades have larger gullets to move the sawdust and can cause jumping.  Worth looking into. All the preceding suggestions are spot on.

[SCROLLSAW703]

Howdy Mr. Scott, and might I first welcome you to the forum, Sir.

In this situation, there are many variables involved. You have been given more than plenty of dandy suggestions to begin with.

Might I ask, what breed of saw are you usin', Sir? As mentioned, is there a possible aggression adjustment? If not, and you're not usin' an overly aggressive blade, try backin' off on your feed rate just a little. Maybe.

Another suggestion may be to try a couple different types of blades that may suit your style of cuttin', Sir. Might I suggest the Polar blade. The polar blade is a blade made with teeth similar to a skip tooth blade, except the teeth are closer together the full length of the blade. And, depending on the thickness of the material your're attemptin' to cut, the polar blade is an exceptional blade for fine line cutting, fret work, as well as other types of cutting, too. 

Blade speed has a lot to do with wood jump. In some instances, blade speed is running so fast that it cannot do it's job, and grabs a catch in the kerf, and you have a jump, and sometimes a broken blade. Maybe adjust your blade speed accordingly?

I have a number of years at the saw myself, as well as a number of other members here. I learn something from every single project I produce, large or small. I have learned over the years what thickness' work best for me, what blades work best for me, and I keep all those blades on inventory. Imo, it is might near an impossibility to steer folks towards a given type of blade. It is simply a matter of personal choice.

There is another strong possibility that may be at question yet, too. You may be"pushing" the material into the blade instead of just allowin' the blade to do the work for you. That is an issue that can be checked when you're cuttin' by simply backin' off pressure on your material against the blade. If the blade straightens up or pushes back towards ya a little, that's tellin' ya you are pushin' instead of lettin' the blade do the work. Be worth a try. Also, make sure your blade tension is set proper, Sir.

Sawdust703(brad)

[Scruffydog]

Thanks for the many helpful ideas. I have now switched to the new saw (see buying a new saw thread) so we shall see how it goes from here.

I have a variety of Olson blades along with FD assortment. However, I am by no means an expert and am still in the experimental stages. PS Wood blades are also on the way. Cut something out on the new saw last weekend with no jumps. This weekend's project is a toy car. We'll see how I do on that. No football, below zero temps, Friday off, new saw, fresh enthusiasm thanks to y'all.... Should be fun!

I'm thinking that a notebook to record project, wood type, thickness, blade choice, speed, and results might be a good idea for my feeble mind....

[Sycamore67]

It would be great to have more info.  What blade are you using.....name, type and number.

What wood are you cutting....species and thickness.

Different wood species and blades react differently.

[tgiro]

I've found  that the wood tends to jump when I'm feeding to fast or I have the speed set to slow. Makes no difference which blade, except it happens more often with the larger blades. So maybe it's just a matter of slowing your feed or upping the saw speed a bit.

When I'm teaching, I find that people want to start pushing the blade into the wood before the saw is running. Makes that wood slap every time, but some folks have a hard time realizing why.

[Scruffydog]

My technique is to let the saw reach speed and then ease into the cut. I usually set the speed to about 50%. On the old saw, cutting pine was a problem. However, there was a huge hole in the table for the blade to pass thru, with no insert, and that always gave me the willies. I took the hold down off of the old saw and would have to press down fairly hard to keep the saw from jumping. Vibration was quite high, with quite a range, as measured by by vibration app on my phone.

The new saw so far is completely different. The vibration is much lower and in a narrow band. I believe I have it mounted correctly with ample foam under it. I wish I could remember what blade I used. It was an Olson blade, I think. Hence the need for a notebook to write down the particulars of what I try.

When I cut my first project on the new saw, using the cheap blade that came with it, (unknown # of teeth, pattern, thickness, etc) I approached the cutting in the same manner, with a bit of trepidation, expecting it to jump all over the place. That never happened so I was pleased. With a quality blade I think it should do much better.

Should have some time to check it out again this weekend with a better blade on a better project. Will report results here.

[Sycamore67]

I think to solve your problems you need to spend a bit of times learning about blades.  There are number of types but some of the most common are skip tooth, reverse and ultra reverse.  Each type has its own characteristics for cutting.  Olson blades has a chart with good information.

 

Olson-scrollblade-chart.pdf

[fordamir]

I agree there is a learning curve to every tool.  Only the user can fund the sweet spot and little tricks for their partiular saw.  The only problem is it takes a good deal of cutting time to really get the hang of saw.  Change saw same thing all over again

[SCROLLSAW703]

Every new tool, new blade, new anything to you has a learning curve. You have to work thru that and learn the machine itself. Every sound, every tick, every movement of it.

Then, while you're cuttin', learn the sound of every single blade you use. What it sounds like in different woods, under aggression, with light pressure into the blade, whatever. That's what it's about. It all takes time and practice. You'll figure it out, and we'll be here to walk ya thru yer tights. 

The first two most important things to learn though, no matter what else happens, 1) Learn that machine and everything about it, inside & out. 2) Keep in mind, EVERY single blade chart you look at is only a recommendation for blade size and use. You, and only you have to figure out what blades will work the best for your type of cutting, and go from there.

Avoid plywood at all cost if possible. 1)The adhesives between the layers will dull any type of blade faster than you care to change'em. 2) Plywood is known for "voids" and does have a tendency to tear out and leave a catch, especially if you are using a very aggressive blade. Therefore, creating your "jump." 

Whether you're cuttin' soft or hardwood, look after your blade kerf. Sometimes, with given types of blades, if your blade speed may be to slow, the blade kerf is not bein' cleaned out by the blade proper. Therefore, sawdust builds up in the kerf and binds up your blade. Sounds might near impossible, huh? It happens. There are several things to look at here, and as Sycamore mentioned, we're kinda short on some information, so we aren't fully able to do our job. He also mentioned getting to know a blade size chart. Good advice. 

Another friendly piece of advice, practice, practice, practice.;) Keep makin' sawdust!

Sawdust703(brad)

[Juan Rodriguez]

Any information/experience about PS Wood scroll saw? I am considering purchasing a scroll saw and I like what I have seen about the saw.

Thanks!

[OCtoolguy]

On 1/22/2019 at 7:30 PM, SCROLLSAW703 said:

Every new tool, new blade, new anything to you has a learning curve. You have to work thru that and learn the machine itself. Every sound, every tick, every movement of it.

Then, while you're cuttin', learn the sound of every single blade you use. What it sounds like in different woods, under aggression, with light pressure into the blade, whatever. That's what it's about. It all takes time and practice. You'll figure it out, and we'll be here to walk ya thru yer tights. 

The first two most important things to learn though, no matter what else happens, 1) Learn that machine and everything about it, inside & out. 2) Keep in mind, EVERY single blade chart you look at is only a recommendation for blade size and use. You, and only you have to figure out what blades will work the best for your type of cutting, and go from there.

Avoid plywood at all cost if possible. 1)The adhesives between the layers will dull any type of blade faster than you care to change'em. 2) Plywood is known for "voids" and does have a tendency to tear out and leave a catch, especially if you are using a very aggressive blade. Therefore, creating your "jump." 

Whether you're cuttin' soft or hardwood, look after your blade kerf. Sometimes, with given types of blades, if your blade speed may be to slow, the blade kerf is not bein' cleaned out by the blade proper. Therefore, sawdust builds up in the kerf and binds up your blade. Sounds might near impossible, huh? It happens. There are several things to look at here, and as Sycamore mentioned, we're kinda short on some information, so we aren't fully able to do our job. He also mentioned getting to know a blade size chart. Good advice. 

Another friendly piece of advice, practice, practice, practice.;) Keep makin' sawdust!

Sawdust703(brad)

Reading this makes me sad knowing that Brad is gone too. Between Brad and Les Grenz (Rockytime) I've lost a couple of great friends.  So sad!

 

[OCtoolguy]

20 hours ago, Juan Rodriguez said:

Any information/experience about PS Wood scroll saw? I am considering purchasing a scroll saw and I like what I have seen about the saw.

Thanks!

They are supposed to be tanks and pretty well made. But before I'd buy one, I'd take a good hard look at the Hegner saws because of the difference in how they change speeds. The PS Woods saws still use a belt/pulley system and the Hegners are controlled with a rheostat electronically. But with that said, before I'd buy either of them, I'd be searching for used saws and or take a look at the Hawks as they are the same type of mechanism. They are all great saws but expensive. I'm a firm believer in buying used when I can. As the old saying goes, let the first buyer take the hit. A car drops a huge amount as soon as it hits the street. In normal times that is. Right now, used cars are escalating in value. 

[timelett]

I think also that hardwood seems to cut different across grain versus with grain? With grain seems to cut slower and I need to feed slower.

[TAIrving]

On 1/7/2022 at 6:21 PM, Juan Rodriguez said:

Any information/experience about PS Wood scroll saw? I am considering purchasing a scroll saw and I like what I have seen about the saw.

Thanks!

Looking at their website, both scrollsaws are "Out of Stock".  That has been the case every time I have looked which has been infrequently.  Does anyone know if they are still making/selling them? 

[Juan Rodriguez]

23 hours ago, OCtoolguy said:

They are supposed to be tanks and pretty well made. But before I'd buy one, I'd take a good hard look at the Hegner saws because of the difference in how they change speeds. The PS Woods saws still use a belt/pulley system and the Hegners are controlled with a rheostat electronically. But with that said, before I'd buy either of them, I'd be searching for used saws and or take a look at the Hawks as they are the same type of mechanism. They are all great saws but expensive. I'm a firm believer in buying used when I can. As the old saying goes, let the first buyer take the hit. A car drops a huge amount as soon as it hits the street. In normal times that is. Right now, used cars are escalating in value. 

Thank you, Ray!