MDF or Wood 3D cutting

[GJHall]

I am new at 3d cutting, well, I want to give it a try.

I have some 1" MDF that was given to me from a job for table tops.

I was wondering if this 1" MDF would be good for 3d cutting as I am just in the learning stages. If this worked, then I can attempt to use wood for my final cut project.

Thanks

Gary

[Rcnewcomb]

MDF is a good material for learning 3D machining. With a good finish is can be indistinguishable from real wood. Below is an example I did in MDF and applied a finish so it looked like cherry. A number of wood workers examined it up close and could not tell that is was MDF.

[4DThinker]

Just be prepared for the dust created while milling MDF. Not at all like milling wood.

[highpockets]

Randall,

I never imagined MDF could look so good! Nice work.

Maybe I should rethink MDF.

Would you be willing to share your finishing methods?

[GJHall]

Just be prepared for the dust created while milling MDF. Not at all like milling wood.

Yes, I use a dust collector with a dust boot. Works well for V carving and straight cut outs.
I just don't want to spend alot on wood and mess up. The MDF was given to me so nothing to really lose except for time. Thanks for the replys.

Gary

[highpockets]

Besides the dust MDF will also dull your cutters faster than wood.

[Rcnewcomb]

Maybe I should rethink MDF.
Would you be willing to share your finishing methods?

I learned the technique from Danny Ray over on the ShopBot forum. I also visited his shop in Costa Mesa, CA and looked at his work up close.

Here is a link to the archived discussion thread: Finishing MDF to look like wood?

Here is an example of Danny's work in MDF:

[highpockets]

Randall,
Thanks for the link, great read, Danny is doing some amazing finishes.

[scottp55]

Nice Randall:)
I was lucky to have a Shopbot artist(Robert Rickard) visit Dad and I in October, and he had just started working in 2" MDF/aluminum/ and Sculpt Nouveau finishes.
I was impressed!
scott

[Xxray]

With some effort, MDF can be Ok for 3D - I wouldn't expect results like Randalls without a lot of effort [didn't read the linked SB thread, bookmarked it for later viewing, thanks].

It is cheap, easily available, machines decently.
As mentioned, the dust is nothing short of insidious and is tough on cutters. Tends to be "soft" and sometimes loaded with chatter/fuzzies which, even when sanded down, can still leave a somewhat textured look.
Absorbs finishes, plan on doing quite a bit more than with wood. Have made 100's of 3D objects and long ago abandoned mdf, but Randall shows where there is a will there may be a way.

I'm not big on painting or spending alot of time with finishes, I generally like to cut, sand, blow and clear coat ,,, And the almost limitless beautiful wood species makes this possible and ever changing. MDF requires a far greater effort to complete, once its off the table you are only half way done - Almost like a model airplane, all glued together and ready for the detailing that will bring it to life.

So alot depends on your outlook and preferences how far you want to get into it.

[LittleGreyMan]

I'll second Xxray.

But sometimes a neutral material can give better results than a beautiful wood. If you choose correctly the piece of wood and if you are a bit lucky, the grain will complement the model. But it can also visually flatten it.

I specifically noticed that on terrain reliefs. Maybe Scott has had the same experience.

As discussed above, it's not a big deal making MDF look more or less like wood, with the advantage of uniformity. That's what Randall demonstrated.

Even with high quality MDF (avoid cheap MDF like plague), I am concerned with "chatter/fuzzies which, even when sanded down, can still leave a somewhat textured look" as Xxray wrote.

Somebody may have already tested this or is willing to test it (I will not have time before weeks):

-offset the model (keep the original one) of a small value to leave an onion skin on the actual model
-machine the model with offset. Roughing and finishing. Or more exactly semi-finishing with a larger stepover (and maybe a larger bit) than for an actual finish
-after removing the dust, seal the mdf, without removing it from the machine. Several coats may be necessary as cut MDF is a real sponge.
-once the sealer is dry, finish the actual model with a finishing toolpath with the required bit and stepover

The actual finishing toolpath will cut a hardened and sealed layer of MDF and may avoid the chatter/ fuzzies issue.

Takes more machining time, but I prefer letting the machine work while I'm performing other tasks.

Once again, never tested, any feedback will be appreciated.

[ger21]

-offset the model (keep the original one) of a small value to leave an onion skin on the actual model
-machine the model with offset. Roughing and finishing. Or more exactly semi-finishing with a larger stepover (and maybe a larger bit) than for an actual finish
-after removing the dust, seal the mdf, without removing it from the machine. Several coats may be necessary as cut MDF is a real sponge.
-once the sealer is dry, finish the actual model with a finishing toolpath with the required bit and stepover

I use a similar technique, but use epoxy as a sealer.
When you run your finish pass, you'll end up with a glass smooth plastic-like surface.

I now use epoxy as an MDF sealer any time I'll be painting the MDF.

[Adrian]

I use high density/deep rout MDF. With that you can get nice little spiral chips rather than the dust you get with the standard shed MDF. The difference between the two is like the difference between Chinese boarding ply and cabinet grade plywood. Downside is that it's very, very heavy.

I find low helix spiral cutters give the longest tool life and I use cellulose sanding sealer for sealing the more porous edges/cut parts.

[scottp55]

LGM,
I've had good luck with the figured wood on Bigtopo cuts so long as the figure was pretty uniform(Lousy luck so far with heart/sap line incorporation), but all mine have been small. Much better luck with Black Walnut and regular 3D's with heart/sap.
I'm still trying to use up some cheapo big box store .75" MDF Dad bought....Using it as my spoilboard sacrificial top layer. By the time I've surface down to .3" it's soft as heck, and fuzzy:(
I've used thinned sanding sealer/thinned lacquer/thinned polymerized Linseed/citrus to get some solids into the punky layer, and 3 coats thinned lacquer works the best if I'm in a hurry(Deft brushing lacquer thinned 40% for penetration of about .05") and can open shop door for fumes. Then a .005" surface skim and it's smooth and about as hard as pegboard material. Linseed works the best if I can time it over a weekend for 3 coats, and penetration is about the same, but surface is much better. Good for a several surfacings.
Decent MDF is scarce here and haven't found a source close enough.
On the Lacewood mountain, I used thinned Linseed and cut the next day with the original .02" allowance finish path...I should have done the finish toolpath, THEN coated and cheated the Z down like .005" as the penetration wasn't quite good enough.
I like Ger's Epoxy method, but sucked enough epoxy fumes working in fiberglass canoes/kayaks/boats when I was younger to last this lifetime
That artist working with 2" High quality MDF had to buy an entire lift to get the good stuff trucked to his shop...He didn't mention any extra step before the Sculpt Nouveau on that experimental piece in the pic above.
Side note is he's now playing with Paul's BigTopo and doing actual locales vs. his arbitrary terrain:) Now he's trying to add aluminum "Lakes" by machining pockets in the back side:)
For uniform 3D's I like Cherry and Sugar Maple.
A couple pics,
scott

[LittleGreyMan]

Thanks all for your feedback.