Jig Saw Problem with MDF

[Len Rosenberg]

Hi folks, I've run into a major issue trying to cut 1/2" mdf with a Festool Carvex 420. After about 8-10 inches of cut, the blade starts to burn, gets bent, goes of track, and becomes uncontrollable. I've ruined 4 blades so far. I have tried all settings from the fastest to slowest, least agressive cut, nothing matters. The blades are fairly thick with wide gullets. I've used this saw on maple and plywood without any issue, cuts straight and leaves a fine finish. This is the first time I've tried to cut mdf with a jigsaw. Can you tell me what the problem is? Many thanks, Len.

[Paul F Franklin]

Sure sounds like heat buildup from the blade not clearing the sawdust. How many TPI are your blades? You need a blade intended for fast rough cuts that will have coarse teeth with more set than blades intended for fine cutting.

[Erik Loza]

Sure sounds like heat buildup from the blade not clearing the sawdust. How many TPI are your blades? You need a blade intended for fast rough cuts that will have coarse teeth with more set than blades intended for fine cutting.

This is my thought as well ^

MDF is nasty stuff on tooling and retains a lot of heat during the cut. Though it seems counter-intuitive, a ripper-type blade would probably perform better. Good luck.

Erik

[Maurice Mcmurry]

Be sure the oscillation is working. (I assume the Festool has it although I do not find a reference to it) I have used a Bosch and now a DeWalt. I cut MDF often, I have not had any problems. I use Bosch blades.

Looks like an awesome saw, the oscillation is obvious in the videos.

[Len Rosenberg]

Thanks for the replies. I was using a 6 tpi blade. That is the lowest tpi blade I have.

Eric, nice to hear from you! Don't know if you recall, but once upon a time I bought a Minimax FS41 Elite and S500p band saw from you. Both are champs of my shop. You were incredibly helpful. I see you are with Felder now. Glad you are still on the forum.

Best regards,

Len

[Tom Bender]

You may have some unusual MDF, made with rocks or unusual glue. Try cutting it with your best hand saw. No wait!

[Frank Pratt]

I have occasionally seen sparks when cutting MDF.

[Maurice Mcmurry]

I see sparks too. On mine they come from the back of the blade where it rides in the Roller. That is when I know I am pushing too hard. They spark when I saw into a Kreg screw someone has snuck in too. I do not use kreg screws.

[Mitch schiffer]

I bought some carbide jig saw blades and they work great and last a long time. I haven't used them much at all on mdf. I use them mostly on vinyl flooring and solid surface coutertops. It might be worth a shot if a blade with fewer teeth doesn't solve the issue.

[Derek Meyer]

There was a thread a while back where someone said they got some MDF that was imported from China and it contained bits of metal. It actually set off the brake on their Sawstop.

I had difficulty cutting MDF recently with my jigsaw. The blade would actually come out of the saw after a few inches (Dewalt 20V cordless). I'm pretty sure the blade had too many TPI and the gullets weren't clearing and the blade would heat up and jam. Fortuanetly, I only needed it for just a few inches of cut in each piece, but next time I will go with a blade with fewer TPI.

[Richard Coers]

MDF is very abrasive. If you were using steel blades on your table saw, the result would be the same. Carbide makes the difference.

[Erik Loza]

..Eric, nice to hear from you! Don't know if you recall, but once upon a time I bought a Minimax FS41 Elite and S500p band saw from you. Both are champs of my shop. You were incredibly helpful. I see you are with Felder now. Glad you are still on the forum.

Best regards,

Len

Len! I do remember you but just somehow skimmed through your first post and it just didn't click in my head. I am so glad to connect with you again and happy to hear your MM machines are running well. Don't ever get rid of that S500P, by the way: You literally cannot get another one. Stay well.

Erik

[Maurice Mcmurry]

I am looking around the web to see if MDF is ever rated by APA or others agencies. I am not finding much other than the formaldehyde ban. All of the MDF I am familiar with is from Lowes Or Liberty Hardwoods in KC. I have never had these problems. I always use carbide blades for all circular saws. I have not tried carbide jigsaw blades. I use steel bandsaw blades for MDF often with out any problems. Even a very good jig saw is a limited tool. The sawzall is also limited. Reciprocating action is my least favorite way to cut most things. I have started to use Freud Diablo carbide sawzall blades. They are great.