How to avoid table saw fuzzies?

[Keith_W]

Today I made the cheeks of my gunport carriages and cut them out on my Byrnes table saw. I am generally happy with the results, except: 

 

 

 

You can see that the edges of the cut are not clean. The little splinters shave off nicely with a knife, but it is extremely tedious having to clean up dozens of these little things. You can see that the problem is more pronounced with some cuts than others, which makes me suspect that it is operator error rather than a problem with the machine (dull blade, etc). 

 

What have I done wrong? Am I feeding it too fast? Do I need to place closer attention to the grain? Do I need new blades? Or ... do all of you have this problem? 

[kruginmi]

Can you provide a pic of the Byrnes setup you are using with one of the carriages nearby?

 

In my experience it all comes down to height of the blade and speed you push the wood through (coupled with ability to clear the debris away from the cut).

 

Mark

[Rustyj]

Hi Keith. As Mark said height and speed are important. I've also noticed that the number of teeth per inch can have something to do with it too. You may need to use a higher TPI blade.

[figuerres]

I would also look at # of teeth and the way the cut is related to the grain and the speed of the saw and of the push. also the type of wood you are cutting has an effect on this, how tight, straight and how hard the wood is.

 

from what I see it does not look bad as long as the fibers are not pulling out bits of wood on the side they are rough.

that would be a problem.

 

I think also this is one of the reasons why kit's are laser cut ...

[Boatsinc2000]

TPI...saw blade selection. Go finer.

 

Jeff

Hobbymill

[Keith_W]

Mark, Rusty, figuerres, and Jeff - thank you for your responses. This is a picture of my Byrnes setup, as requested: 

 

 

 

- I am using the 80 tooth .04 kerf blade supplied by Byrnes

- the blade height has been adjusted to just clear the top of the workpiece

- I have indicated the direction of grain in the second picture

- the wood being cut is Swiss Pear, supplied by Jeff from Hobbymill

 

I guess I need new blades. I read Jeff's Byrnes Saw Operation page again last night (here: http://www.hobbymillusa.com/byrnes-saw-operation.php) ... i'll be ordering new blades.

Edited February 18, 2015 by KeithW

[kruginmi]

You might be right with the new blades but I would suggest a change to avoid pinching the cut off pieces between the blade and the guard.

 

The best and safest option is to use a sled.  That way everything moves through the cut.  Everything can be held down.  I constructed the following as an example:

 

 

This is pretty easy to build but is very versatile.  You can affix a spacing piece against the back block to get your repeatable width requirement.

 

Mark

[Jaager]

The direction of the grain!

This probably the reason for the fuzzies.

Any torque and the piece would snap.

The appearance - if not sealed and painted, is unnatural.

The grain should follow the long axis of the piece - and horizontal.

You will not get as many units from the milled stock, but just mill more stock pieces.

[popeye2sea]

I think Mark is right.  You are getting chatter from the unsupported piece passing between the blade and the fence.

[Keith_W]

Thank you all for your feedback. Jeff/Henry, I am not sure how to support such a thin piece, even with a sled? I will try out all the suggestions and report back. I have to fabricate two more batches of gun carriage cheeks in maybe a month, once I reach those decks. This time, I will: 

 

- have new blades, 

- make sure the direction of the grain is in the same direction as the cut, 

- construct myself a sled. I probably need one anyway. 

[mtaylor]

Keith,

 

I think Jeff was spot on.  Hit his webpage and get the info on blades.  I ordered blades for my "not the Jim Saw" from Thurston and fuzzies, etc. are thing of the past. 

[Boatsinc2000]

Keith,

 

Thanks for the pics.  You may have tried this already, but you may want to reverse your cut by cutting the back of the carriages first.  The tear out usually occurs on the backside of the piece so instead of having the fuzzies on the stepped edges it would be on the more consistent front edge.  Also adding some masking tape to the backside of the cut will help too.  It's a common carpenter's trick.

 

Couldn't tell from the pics if you have a stop setup on the fence ahead of your cut.  If not, you may be experiencing kickback.  Typically you should not use the miter and the fence on a cut without a stop.  Pick up a book on tablesaws at your local library as there should be some good tips regarding setup.

 

Finer pitched blade may help a little, but mostly changing the orientation and adding the tape should get you most of the way home.  Also going slowly when the blade exits the wood on the backside will help too.

 

Good luck!

 

Jeff

Edited February 19, 2015 by Boatsinc2000

[Keith_W]

Thank you, Jeff.

 

By the way, I have managed to cure it ... somewhat. I figured that SLOWING DOWN the rate which I make the cut would have the same effect as buying a blade with a higher TPI - in other words: by advancing the cut more slowly, more blades will hit the wood per unit of distance. This is the same as having a higher TPI blade and pushing the cut through quicker ... unless there is some other variable which I haven't considered! 

 

I do have a book on table saws which is on my Kindle reader. I have learnt so much from it, but I learn even more from actually making the cuts. 

 

I will try the masking tape. I love solutions that don't cost me money! 

[lehmann]

I think the main reason for the tear-out (fuzzies) is that you're using a rip tooth for cross-cutting.  The rip saw tooth is basically a square chisel that tears, more than cuts, grains. A cross-cut tooth needs to have a angle on the tooth face and ideally on the top as well.  This design creates a high point on one corner of the tooth that cuts/scores the wood fibres.  

 

I haven't seen any small circular saw cross-cut saws being offered for sale anywhere (is Jim Byrnes listening?), but you can re-sharpen a rip saw with a small triangular file.  It's not difficult. See http://www.vintagesaws.com/library/primer/sharp.html for hand saws, but the same idea holds for filing circular saws. 

 

The second possible reason for tear-out that the feed is too fast. This obviously creates a larger bite for each tooth and larger forces on the wood grains.  At the end of the cut, these grains are unsupported, so they bend rather than get cut.  This the reason that zero-clearance saw throats and miter guides are used - to support the fibres at the end of the cut.  To make use of this, I would have fed the piece from the other side so that the long (outboard) edge would be against a sacrificial extension on the miter.  As you've done it, each step of the profile is unsupported at the end of the cut.

 

The third reason is related to the size of the tooth relative to the depth of cut.  Each tooth has to have enough volume in the triangular section (called the gullet) to hold and carry all the sawdust that is produced at the tooth tip.  As the feed or depth of cut increases there is more sawdust to be stored in the gullet.  If the gullet gets too much sawdust then it will be under pressure so that at the end of the cut the sawdust pressure will blow the final fibres out before they are cut. Generally, smaller teeth (more teeth in a saw) have smaller gullets, which is one of the reasons fine-tooth saws can't be fed fast.  

 

As a last point, I would have made the profile to run across the grain, then ripped with the grain.  Phillip Reed shows this in his book "Period Ship Modelmaking". As you've done it, the carriage cheeks are very fragile and the surface is rough, which means a lot of sanding or a lot of paint.   

 

Bruce

[keelhauled]

Keith,

 

Thanks for the pics.  You may have tried this already, but you may want to reverse your cut by cutting the back of the carriages first.  The tear out usually occurs on the backside of the piece so instead of having the fuzzies on the stepped edges it would be on the more consistent front edge.  Also adding some masking tape to the backside of the cut will help too.  It's a common carpenter's trick.

 

Couldn't tell from the pics if you have a stop setup on the fence ahead of your cut.  If not, you may be experiencing kickback.  Typically you should not use the miter and the fence on a cut without a stop.  Pick up a book on tablesaws at your local library as there should be some good tips regarding setup.

 

Finer pitched blade may help a little, but mostly changing the orientation and adding the tape should get you most of the way home.  Also going slowly when the blade exits the wood on the backside will help too.

 

Good luck!

 

Jeff

 

As Jeff points out that "you should not use the miter and fence on a cut without a stop."  Hopefully you're not using the fence to setup the thickness of your cut.  On larger pieces and a saw this is a serious issue and could create kickback that could end up with severe injuries and loss of fingers.

 

Just wanted to comment on the safety aspect.

Edited June 20, 2015 by keelhauled