turning MDF

Re: turning MDF

robo hippy

Biggest problem that I know of is dust, really fine, and lots and lots and lots of it. There are some types of it that are made with formaldehyde free resins, so not too bad that way. The glue will dull the tools quickly.

You making a form for a mold? I have done a couple of those...

robo hippy

Re: turning MDF

eliot feldman

No, it's not for a form, Robo. I have an artist friend who wants a large, 20 inch dia. shallow "bowl" (platter?) that he wants to set into a panel to paint fine art on. This particular artist is known locally for his shaped "canvases", which is to say that he usually paints on a panel that isn't rectangular. They usually have straight sides, but they have odd cross-shapes, or L -shapes. This time he wants to experiment with getting away from the ordinary in still another dimension -- namely INTO the panel. After some consideration on my part of how to turn something this large that would be fairly cheap and won't warp later, I settled on three layers of 3/4 in MDF from the BORG. They are gluing up now, and I plan to turn them soon.

My dear wife of nearly 50 years (June19th) doesn't want me to do it because of the harmful dust. But I thought I could get away with it with proper precautions.

Re: turning MDF

Dick Coers

If you don't use a dust collector, you will have a coating on everything in your shop. It's like a dust explosion when turned. Keep an eye on your dust collector, if you don't have a cyclone, it will coat the bags really heavily and reduce suction. As mentioned, you will really be shocked how fast that stuff will dull a tool. There are different densities of MDF, and if you have an industrial supplier near, see if you can get light weight MDF. It's going to take a lot of effort on the artist's part to seal the surface. Sanding for you will also be a challenge. The faces of MDF are much more dense than the interior. If you laminate several pieces, it's going to me a mix of densities through the piece.

Re: turning MDF

Doc Green

To keep the dust to a minimum, use a very sharp cutting tool and have the blank rotating as slowly as possible. Then push hard on the tool to force the cut. The idea is to produce "stringers" instead of dust. For a 20" blank, I would go for about 100 RPM.

You can turn it faster, but you will make a lot more dust. Also, avoid traditional scraping. Shear scraping is not so bad, but pure scraping will generate tons of dust.

Re: turning MDF

eliot feldman

The artist plans to coat the surface with gesso. I believe he will do all right with that.

Re: turning MDF

eliot feldman

I'm glad you posted. I would have tried to turn faster. I'll slow down, as you suggest ,and try to get strings instead of dust. My tools are sharp, and I sharpen on a couple of those carbon boron type wheels. I expect the tools to dull quickly. so I expect to sharpen often.

Re: turning MDF

don stephan

Using a shop made trammel you could remove as much as possible outside with a router. A cohort could hold the end of a shop vac hose beside the router to catch as much dust as possible.

nasty stuff

GaryG in MD

Eliot,

I have turned it, and I did not enjoy the experience. As everyone has said, the dust is terrible. And it clings by static electricity to everything it touches and does not clean off easily.

The idea about having somebody standing with a shop vac (rather than letting most of it go into your dust collector) is a good idea. But it will quickly tend to clog your filter if you have one.

You should also be concerned about fire and even a dust explosion.

Frankly, it seems to me you would be a lot better off with plywood, even given the extra weight. My 2¢.

...GG

Re: turning MDF

Barry Irby

I agree with all of the above about the dust, dulling tools and the dust. Lots of dust.

Can you make your blank out of a solid disk and one or two concentric rings to reduce the turning as much as possible?

other options?

John K Jordan

I wondered about the same thing, maybe even use a router jig to make a ring frame, perhaps even in segments,then glue in a flat circle. Or just turn it from a slab - I have some 20" wide slabs of 2" cedar and sapele I've saved for platters - both are quite stable when when made into platters. A local sawmill might have some wide slabs.

Hey, how about gluing solid wood onto a circle of MDF first and just turning the rim and not the MDF? The solid rim could be segmented.

I would hate to turn the stuff. If I did, I would want to drag the lathe outside AND set up a big fan to blow the dust away from me. I don't even like to cut the stuff on my saws when making jigs!

JKJ

Re: other options?

Gary clarke

I agree with John, segmenting is the way to go if you can not find a large slab. MDF is not worth the risk. Turning MDF outside with a large fan at your back would be the second best alternative.

Substrate

John Kaner

MDF when properly sealed makes an excellent substrate. Amazing that it shows up in high end furniture. Really heavy too.

Mr Bill Young, a Canadian turner, suffered a compound fracture to his arm from turning MDF.

The kind I've seen has a paper coating. The inner core will fracture quite easily. I think the paper is there for a smooth finish for paint, etc. The ends and middle suck up finish and swell.

Early laminate flooring had this in it. Water leaks caused the laminate flooring to fail from the swelling.

I would go with plywood, much more stable and no formaldehyde! This formaldehyde off-gasses for years.

I like the idea of using segmented wood and the plywood. With gesso it will be a nice surface for paint.

Turn it! (pic)

Doc Green

This shows the stringers that come off MDF when you turn it very slowly and force the cut with a sharp tool.

This pile of "shavings" was produced by turning about an inch off the diameter of a 6" disk, which I did in under two minutes at 200 RPM. The stringer draped over the disk was over 4 feet long and reached all the way to the floor.

You can see some dust in the shavings. Most of this was produced when I inadvertently let up on the pressure on the tool - a 5/8" bowl gouge. I had my dust collector ON, but not close. There was no visible dust in the air.

You can do it! ~Doc

Re: turning MDF

john lucas

I've turned it. It's nasty but you just take precautuions. You probably won't want to turn it again because it is very dusty. Wear a good dust mask and take a good shower afterwords. You might want to strip at the door as well if your married and want to stay that way.

The problem with most other materials is they need to be sealed properly to paint over them. Plywood is especially bad for having holes and tearout that needs to be filled. Apple ply and baltic birch are better choices.

I agree with segmenting with a degree of caution. I would use yellow poplar. Turn it, sand it roughly and then let it sit for a week and then sand it again. Other wise you will have glue lines that show. And they will probably creep back in later in it's life as the wood moves differently than the glue. You will probably have the same problem with glue lines on the MDF as well.

Well, I did it

eliot feldman

Everybody's absolutely right about the dust! The worst dust occurred when truing up the blank. Once inside the bowl, by following advice here about turning slowly, I got mostly long, long strings; and this part wasn't quite so bad. The stuff does turn like butter with a sharp gouge. Also, I discovered, really for the first time, that using the 40 degree grind that you hear much about worked very well on this fairly large shallow MDF bowl-- I would say much better than my other Ellsworth-style gouges in this application.

I don't really want to do it again; this was a special project.