Mdf???

[mackmack]

I have another thread going which has sorta helped me out regarding this but it was pretty buried.

I just have a few quick and simple questions though regarding this stuff that I'm sure the majority of you guys probably know.

MDF... How easy is it to cut? I heard its bad for your saw blade.. How is it for painting...better then ply? Can I cut smaller pieces .7 inch strips and expect them to not crumble and remain rigid?

What about ripping and crosscutting... I have seen the stuff and it doesnt seem to have a grain.. is that true? if so how do you cut it safely?

Lastly, will all wood glues react and hold the same as they would with plywood?

thanks alot everyone!!!

[Knottscott]

MDF cuts very easily but dulls blades pretty quickly. It creates a very fine silt that makes a slippery mess and is bad to breath...wear a respirator when kicking up this dust. There's no grain so use the longer sides against the rip fence, and the crosscut the shorter side with a miter or SMT. It paints better than ply IMO, but the edges benefit from some spackling followed by primer. MDF does not hold screws particularly well and is not very strong horizontally....0.7" strips should be fine by themselves but watch how you secure them, watch the spans, and be wary of loads. Yellow glue works fine on MDF. If you use screws, use a coarse thread and very low torque....I'd also reinforce with glue.

[MilDoc]

I have to agree with everything Dustmight said. Dust is BAD. And when using MDF I stick with Confirmat screws and always predrill AND use a clamp when inserting the screw into the end.

[mackmack]

Great info like always guys, If you charged for this stuff I would be broke(well, broker then I already am

This dust you guys are talking about sorta worries me..I live with several family members and although I do my work in the garage that is usually open(at least in the spring/summer/fall) will particles that have fallen to the ground be dangerous? ...meaning can I cut for a few hours(i have a shop vac on the exhaust hole) and clean up after without them or myself being at risk?

Also, the respirator thing. Is that just one of those masks with the filters sticking out the front. I was in the marines(infantry) and wore a gas mask all the time but I can't say it was too comfortable. Is it just a matter of wearing while the stuff is in the air?

DustMight, what type of spackle do you use. I just got done tearing down wallpaper, spackling, and painting pretty much the whole interior of our house but I am assuming that's not the type of spackle you are talking about. Any recommendations on type and brand? thanks.

Sorry for the excessive, and ridiculously amateur, questions but I have never had anyone in my life teach me so much as how to paint or change a flat tire.

[RodKirby]

Kirby's opinion (years of using MDF!).

• Titebond I, II, and III will work just like it does on other "wood" stuff.
• My Shopvac has taken care of me for around 15 years (last x-ray 3 months ago ) I always have an overhead fan running slow to take care of any air-born dust.
• I have never worn a respirator or even a mask in working with MDF, BUT; I'm sure it would be better protection.
• I have found the first coat (of anything) is sufficient to seal the MDF. Light sanding and then (say) 2 final coats will give you the same finish as you would get on plywood.

YMMV

[MilDoc]

First the best, most comfortable dust mask made - DustBeeGone!!!! Note that this is a dust mask, not a respirator like from AO Safety for fumes:
http://www.dustbeegone.com/

Second, I agree with Rod. I used a ShopVac attached to the BT3 on my first project. Worked OK. Then I added a SharkGuard and a "Y" to the Vac. Better. Now I have an HF dust collector connected and that is good! But still have to vacuum!

And his advice on finishing -- well, what can I say? He's THE ROD! Still can't figure out he keeps his shop so clean, unless he has Maid service!

[Knottscott]

I don't think tracking in MDF dust is gonna cause any harm other than annoying SWMBO. It hsa very fine particles that get into lungs and there's lots of glues and who knows what other manmade stuff it in that you're better off not breathing...having some awareness of it is a good start. It's better off in a garage than a basement using forced circulated air through the house. A good vacuuming should clean it up from the garage. By dustmask, I don't mean a full rubber respirator...just one of those disposable paper or spun poly particle masks held on by a rubber band. I use my DC and don't wear a mask unless I'm cutting or routing lots of it.

Any old drywall spackle should do.....just glob it on and sand it off. The object is to fill any voids.

[SARGE..g-47]

I might add not to use MDF for outside projects as it doesn't mix with water well. Not as bad as particle board, but not intended for outside as the layers will waffle after being saturated with water.

I use it to make shop bases, tool tops, etc. Comes .004 flat surface off the shelf and the face is very closed. Doesn't hurt to scuff the surface lightly with 120 grit to get some adhesion for paint.

I wear a mask.. I also open the door behind my TS and place a 24" cage fan on my worlbench facing the saw and out the door when I cut it. The DC is also connected to the rear port. And when I'm done, I take an electric leaf blower and start at the back of the shop. Again wear the mast and blow the whold thing out with all doors open and go up for coffee. Give all time to settle and back to work.

In the picture below visualize a 24" fan on the workbench behind me facing the saw and out the open door. Very little gets a chance to permeate the rest of the shop. Second pic is my router table. Top and base made of guess what? MDF.. of course. Table top edges are sealed with a band and 3 coats of poly under. Top is sealed with Mica. .002 movement in 4 years. Very useful stuff. Just wear the mast as you should with all dust particles floating around.

Regards...

[BigguyZ]

I've worked with MDF when doing my speakers. I have to disagree with any sentiments about NOT wearing a respirator. Although I do work in an enclosed basement, from what I've been told MDF is made using Formeldehyde, which is fine for corpses but not for the living. When I cut it (mostly w/ a router, didn't get the TS until after most of the speaker work was done) it made a super fine dust that went everywhere, covered everything, and stayed in the air for 20-25 minutes afterwards. Now if you aren't in a similar workspace you may have better ventilation, so take my advice with a grain of salt...

[mackmack]

wow, now that is a nice looking set up. I have some of those orange clamps in the background...but other then that I have a very humble work area right now.

Thanks everyone for the great info...once I get some money I am going to start cutting and putting to use all your suggestions.

[steve-norrell]

Respirator or not?

I learned from experience that a respirator should be a high priority item when working with MDF, or with any substance that might trigger allergies. Even if you are not sensitive (as with hayfever-type allergies) you could become so with repeated exposure, especially if you tend to be sensitive to pollen and other airborne contaminants.

Another thought -- you should also be concerned about fumes from solvents and glues. The usual advice about using in a "well ventilated area" applies, but, again, if you tend toward sensitivity, a fume-grade respirator should be considered. Read the warning label on Gorilla glue if you want an example.

Believe me, I know. The inconvenience is more than made up for by being able to breath normally afterwards.

Good luck.

[mackmack]

yeah, so I figure I will just use a respirator then. Better safe then sorry.

I wanted to be sure though about something with MDF. It has no grain so is kickback not a problem at all? I still cut my large cuts by ripping and shorter by cross-cut but I just wanted make sure that there weren't any little tricks or precautions I should be taking since this is my first time cutting MDF.

Also, I am planning on buying a new blade soon because someone gave me the good idea to have 2...so that when one is being sharpened I can use the next.

Can you guys recommend the best blade for cutting MDF?

Thanks a lot for all your comments and suggestions like always.

[RayintheUK]

I wanted to be sure though about something with MDF. It has no grain so is kickback not a problem at all? I still cut my large cuts by ripping and shorter by cross-cut but I just wanted make sure that there weren't any little tricks or precautions I should be taking since this is my first time cutting MDF.

It's true that MDF does not have "grain." It's OK to cut the long cuts by ripping and the shorter ones by crosscutting. However, grain is not the only (or even, necessarily, the primary) cause of kickback, so don't think that because it's MDF that kickback disappears entirely - it doesn't.

Kickback happens mostly when the rear (upwards-spinning) portion of the blade overcomes the forward motion of the workpiece and propels the piece upward and towards the operator. A prime cause of this is skewing the workpiece while cutting. Another is an incorrectly setup rip fence, where the fence is slightly angled towards the blade at the rear. This makes a narrowing gap for the stock to pass through, so it's forced over towards the blade, which then acts like the clutch in a stick-shift until it's able to pick up the piece through friction and hurl it at you. Quite a few have their rip fence set just a hair (business card thickness) the other side of parallel. so that the fence is slightly angled away from the blade, to remove this possibility.

The riving knife should always be used with through cuts and this needs to be correctly set up in order to minimise the possibility of kickback, as it acts as an auxiliary (left-hand) fence at the rear of the blade, preventing the workpiece from binding on the blade as it is passed through.

Crosscutting should never be attempted in conjunction with the rip fence anyway, so the possibility of kickback during a crosscut will be almost entirely down to operator error / poor technique. Further explanation here if required. HTH

Ray.

[mackmack]

Thanks Ray,

I finally learned to set my fence correctly and accurately and I think I will go back and apply the your suggestion regarding slightly angling it away.

I plan on buying a shark guard soon, but I don't intend to use the pawls. Most people on here said that it would be ok, plus I hate the etched lines it creates. Do you have an opinion either way? thanks!

[RayintheUK]

I plan on buying a shark guard soon, but I don't intend to use the pawls. Most people on here said that it would be ok, plus I hate the etched lines it creates. Do you have an opinion either way? thanks!

The idea of an anti-kickback device is fine, but the pawls don't cut it, as far as I'm concerned - they're a real PITA!

IMO, you can lose them as long as you're taking the usual precautions about setting up the fence and riving knife. I removed the pawls on my saw the second day I used it, didn't cause me any problems at all. As you say, loads of other users have also removed them without regret. HTH

Ray.