Woodcutting issue - help me diagnose the problem

[Saneless]

Ok.. I was building a prototype panel for this very reason: It didn't go well.  Now, I was strictly cutting to get a feel for the MDF again (been many years) and right away I had a problem.

It cut a few inches but then, even after trying to let some of the dust clear, it just got jammed up.

I've attached a couple pics.  1 of them (awful cut 1) shows just how ragged and bad the cut was.  I'm sure I'm part of it, but I had to move the blade back and forth a bit to get it to get anywhere.

The second shows what looks like "burns" on the side.  Maybe that's normal but I don't remember it last time.

The blade is a small (1-2mm) many-toothed blade that says it's fine for wood.  Maybe that's the wrong blade?  I don't know, but whichever works best for MDF or both MDF+Ply I'd love recommendations.

Is this just a result of a bad blade or am I a horrible person and I should give up immediately?  At least my spade bit and holes came out just fine

[spoot]

Possible off the top of my head:
Dull Blade
Non parallel blade to fence
Blade backwards

[Generic Eric]

Ok.. I was building a prototype panel for this very reason: It didn't go well.  Now, I was strictly cutting to get a feel for the MDF again (been many years) and right away I had a problem.

It cut a few inches but then, even after trying to let some of the dust clear, it just got jammed up.

I've attached a couple pics.  1 of them (awful cut 1) shows just how ragged and bad the cut was.  I'm sure I'm part of it, but I had to move the blade back and forth a bit to get it to get anywhere.

The second shows what looks like "burns" on the side.  Maybe that's normal but I don't remember it last time.

The blade is a small (1-2mm) many-toothed blade that says it's fine for wood.  Maybe that's the wrong blade?  I don't know, but whichever works best for MDF or both MDF+Ply I'd love recommendations.

Is this just a result of a bad blade or am I a horrible person and I should give up immediately?  At least my spade bit and holes came out just fine

On the package that the blade came in you will see what it is best suited for, if its not on the blade itself. 

No reason to quit because of this.  You have 3 options

Change the blade when you cut a different type of wood
Change the blade when you cut a different type of wood
Get a saw for each type of wood.

Also, are you using a battery powered saw?  I thought I was getting a super deal when I bought a battery powered drill and trim saw combo.

The saw may just be underpowered (like mine seems to be) for the wood you are cutting.  Or the battery is out of juice. 

[Saneless]

Thanks for the quick replies..

God I hope I'm not stupid enough to put the blade on backwards.. but I have no reason to think I couldn't do something like that.  I'll have to check.

It could be dull from the last project, but I don't think it got a ton of use.  Is there any way to tell for sure?  I can tell if a knife or hockey skate blade is dull, but with something that's 1/16" wide it's not like it has a razor edge to begin with.

If the blade was backwards would I even have that much success?  That'd be hilarious if I even got that far with it

As for the saw itself, the irony is the circular was full-juice wired, the drill is battery and had no issues

[shponglefan]

Don't feel too bad if the blade is backwards.  First time I used a slot cutter, I installed it backwards.  Routed an entire slot that way, but couldn't figure out why it seemed so damned difficult.

When cutting MDF you should not have jamming or burns; that indicates something is definitely wrong.

Out of curiosity, what type of saw are you using?  FWIW, I use a 60-tooth Avanti Pro blade in my table saw and have no issues cutting MDF.

[spoot]

Other that I have pondered while unracking servers today......underpowered saw and it's boggin down causing the burn? 

[Saneless]

This is not my exact blade, but it looks a lot like this:

http://ecx.images-amazon.com/images/I/81uGgEVd5iL._SX355_.jpg

Is that the wrong type?  Should it be more like:

http://www.northerntool.com/images/product/2000x2000/m04/m0482_2000x2000.jpg

[yotsuya]

It's weird with saw blades. On my Makita circular saw, I bought a new, expensive blade and had nothing but problems with it getting caught in the wood as I cut, so I returned it (the guy was kind of snooty when I returned it, thinking I was using a cheap-ass saw. He changed his tune when I told him what it was). I then went to Harbor Freight and bought a $4 blade, and it's been PERFECT. 

[Generic Eric]

This is not my exact blade, but it looks a lot like this:

http://ecx.images-amazon.com/images/I/81uGgEVd5iL._SX355_.jpg

Is that the wrong type?  Should it be more like:

http://www.northerntool.com/images/product/2000x2000/m04/m0482_2000x2000.jpg

The first one is for hollow ground plywood. Which, after looking, seems to be the underlayment floorboards but I didn't find a good explainer link. 
The second is for metal

Rip cuts are with the grain.
Crosscuts are perpendicular to the grain, or otherwise across it.

Search "choosing a sawblade by teeth per inch", "select proper saw blade", and "saw blade 101."

Choosing a saw blade can be overwhelming, the range in packs of 3 for 17.99 to 1 single blade for 164.  The last thing you want to do is choose the wrong one.

[Saneless]

My blade doesn't specifically say hollow plywood (just plywood) but now that I think about it, I think I specifically bought it for doing some underlayment. That may have actually been the last thing I cut up.  I thought my last project was a component shelf made out of MDF but I probably had a different blade for that.  Some tools and blades and such got lost (possibly temporarily) when we moved early last year.. so who knows.

And I'll make sure it's not a metal blade, I was just more wondering is it better to have something with a lot of little teeth or sharper looking fewer teeth.

I'll have to do more research and go forward with the assumption that the blade I have isn't actually the one I used on my last MDF project.

[wp34]

Don't feel too bad if the blade is backwards.  First time I used a slot cutter, I installed it backwards.  Routed an entire slot that way, but couldn't figure out why it seemed so damned difficult.

Been there done that and have the burn marks on my slot cutter to prove it.   

[yotsuya]

Don't feel too bad if the blade is backwards.  First time I used a slot cutter, I installed it backwards.  Routed an entire slot that way, but couldn't figure out why it seemed so damned difficult.

Been there done that and have the burn marks on my slot cutter to prove it.   

"WHY THE HELL IS THERE SO MUCH OF THIS FOUL SMELLING SMOKE??"

[Slippyblade]

Don't feel too bad if the blade is backwards.  First time I used a slot cutter, I installed it backwards.  Routed an entire slot that way, but couldn't figure out why it seemed so damned difficult.

Been there done that and have the burn marks on my slot cutter to prove it.   

"WHY THE HELL IS THERE SO MUCH OF THIS FOUL SMELLING SMOKE??"

There wouldn't be soooo many threads about this if it wasn't a common occurrence. 

[Saneless]

All I can say is I did a pretty decent job on it...

...despite the blade being backwards.

Thanks guys

[eds1275]

I use freud framing blades for just about everything. I buy them in a 2-pack for about $20. They are really nice on MDF.

[knave]

I'm not any sort of expert but I do know that the glue content of MDF will dull a non-carbide blade really quickly.
So your steel plywood blade has that against it already. Not to mention if it was already partially dull.

Then the more teeth you have when cutting MDF = more dust = more need for some sore of dust collection.
Bottom line is my gut tells me that blade will bind up once it gets clogged with dust.

-Edit-More appropriate teeth would allow for more self clearing.
I'd use a framing blade myself...

Good luck.

[dkersten]

Yeah that blade is for plywood and for rough cutting on top of that.. about the worst thing you could use on MDF.  It doesn't cut so much as chew the wood up..

Those framing blades posted will work, and really anything with a carbide tooth (not a metal cutting blade) will work.  MDF is really easy to cut, but you need something sharp and with good sized teeth to eject the sawdust, which is always very fine and clogs smaller teeth very fast.  24-40 tooth is what I would look for.. anything higher and you are wasting money and anything lower is going to be an awfully rough cut.  I like the Diablo brand, always had good luck with it.  I use thin kerf blades personally, which are 3/32 instead of 1/8 thick, just because of personal preference. 

As for the metal cutting blade you posted, the main difference between a wood and metal blade is the angle of the carbide tooth.. for metal it is usually perpendicular or even angled a little back so that it doesn't try to dig into the metal, where a wood blade will have teeth that angle forward to bite chunks out of the wood.  Otherwise they are pretty much the same. 

[Saneless]

Looks like it doesn't matter too much.. At Menards they had Birch plywood for about $2 more than MDF.  35% lighter and aside from the hazards of MDF dust, I can't stand the smell of it.  Ending up getting 4 sheets of that instead.

[dkersten]

That blade you have is still going to just chew up that plywood, it is made for rough cutting plywood and OSB when doing rough construction.  If you want any kind of finish quality, get a decent blade with carbide teeth.  Plywood is lighter, but doesn't machine as well, so keep that in mind too, you will want to be careful with the edges, and every exposed edge should be set up to take t-molding, you will never get a reasonable finished edge on plywood. 

A word of advice on plywood:  When cross cutting (cutting against the grain of the surface), you will likely get a lot of grain blowout.  This is where the sawblade coming up through the forward part of the cut will break off splinters instead of cut them, and the edge will be very ragged and very ugly.  Take some 1.5" painters tape and tape it to the surface centered along your cut line.  This will help a little by holding down the wood and preventing it from splintering up.  Also, set your blade to the lowest setting that still cuts all the way through so you are not cutting perpendicular to the surface.  If you are really good with the saw, set it to about 1/8" depth first, make one pass, then set it to the full depth and make a second, this will cut the first layer at a very shallow angle (minimal blowout) and then the second pass will cut the rest.  The underside is usually not a problem as the blade is cutting UP and into the wood, not lifting the surface grain off the plywood.

[Saneless]

Thanks for the cutting advice.

I actually picked up a carbide-tipped framing blade like eds posted earlier, so hopefully that takes care of it.

As far as the depth, I figured that out through my last cut (haven't used the saw in so long, forgot about it) and got it to barely be through the surface, just as much as I needed.  We'll see if I can do the shallow then full cut.

[knave]

You can avoid blowout on plywood by having a piece of scrap under your cut. Set your blade depth to just past your plywood thickness.