MDF for laser-cutting new frames

[rshousha]

Greetings. 

 

I'm about to ship out another wonderful kit from Amati; their Pegasus model. As with Lady Nelson, the the frame is constructed with MDF instead of plywood. I would like to get some opinions about how this material compares with good, old, plywood? 

 

Is there a limit to the size of model that can use this stuff? Has anyone broken such a frame during construction? 

 

In considering future laser-cutting, I am considering sourcing and using this material. What do you think? 

 

Best Regards, 

Rick Shousha

Montreal

www.modellers-workshop.com

 

[GLakie]

MDF also doesn't react too well to water. Moisture tends to make it fall apart. Maybe not good for those who apply wet planks on bulkheads to dry in place.

[Q A's Revenge]

Take two samples about the same size, one MDF and another Ply. Place them in a tray of water for a few minutes and ask me again... :-)

[rshousha]

I appreciate the feedback. More than likely, this would not be a good idea for the R/C people, unless they plan on using the frame to make a fiberglas mold. On the other hand, considering all the effort people go to in order to straighten out warped plywood, it seems to be an interesting solution. 

 

I am a huge fan of Amati. Their kits are a head and shoulders over anything else I carry and my clients swear by those kits once they tried them. 

 

I can't wait for their new kits to come out. It will be interesting to see if they use the MDF in the enormous Victory that is rumoured to be in the works. 

 

Regards, 

 

Rick 

[rshousha]

The question of toxicity is interesting. Since it is made of wood product, why would it be more toxic than plywood? In both cases you are sanding wood and glue. Brian, do you have a couple of links I can have a look at? That's an important consideration. 

 

Regards, 

 

Rick 

[GLakie]

I think MDF would be good for bulkheads if it comes with a warning or something to keep moisture away from it. As a stable platform, it IS better than solid hardwood, and plywood for warping, just keep it away from water.

[rshousha]

So far i know the Lady Nelson and the Pegasus kits come with MDF. I've searched around on this site to see if there are any comments but none of the build logs I've seen actually mention anything. If you can find a log that actually mentions the difference like "hey, wow, this is amazing!!!" I'd like to see that. So far it just seems like an incremental improvement, not a revolutionary revelation. 

 

Rick 

[mtaylor]

Rick,

 

It's the dust and binders used:

 

http://en.wikipedia.org/wiki/Medium-density_fibreboard

http://www.wisegeek.com/what-are-the-health-risks-of-mdf.htm

http://www.hse.gov.uk/woodworking/faq-mdf.htm

 

There's more with a quick Google of "MDF toxic"

[Jaager]

I think you should be careful about terminology.  The transverse parts in POB are actually molds of the cross sectional hull shape rather than being bulkheads and they certainly are not frames.  They are just where a few of the frames would be.  Bulkhead is a useful short hand term to describe the unit, but using "Frame" would cause confusion.

 

MDF is as much the binder as it is wood fibers.  The binder is what would be toxic.  For many of us there is  a philosophical split between using Nature supplied components and man made components. Plywood is a step towards man made for pre 1880's ship models and MDF is major step in the plastics direction.

[Q A's Revenge]

The only sheet material that comes to mind that is weaker and less durable than MDF is fibreboard. The fact that kit manufacturers are using MDF is no surprise, it's cheap and easy to cut. There could be some merit in using it in kits rather than sourcing good quality plywood and that's if it reduces the retail price of the kit. Somehow though I can't see that happening. Given the relatively small amount of sheet material in a kit I can't see why a builder would risk the integrity of hundreds, possibly thousands of hours of work just to save a few pounds or dollars on materials.

[rshousha]

Greetings, 

 

Considering Amati is using this stuff I suspect it has more to do with the speed, ease, and quality of the build than with anything else. After having sold a couple of thousand kits, i can start to see patterns in my clients' reactions to kits. Among new builders, I get the best reviews from people who buy Amati kits. This suggests to me that they are making a great effort to keep things simple and help builders get to the end of their projects. 

 

Speaking of ease or construction, there is a whole new way of putting their copper plates on the bottom of Pegasus. This is another place where I am looking forward to clients' reactions. 

 

As a seller of kits, I am all for increasing speed, quality, and ease of construction. Any technology that adds to the fun of building models, lowers the skill barrier to entry, reduces frustration, and helps keep modellers interested, is most appreciated. 

 

To me what is important is the final product. Does it look realistic? Is it clean and sharp? Will people want to keep looking at it year after year? 

 

The new technology and materials coming on line is most exciting. Perhaps the MDF is not quite the right product for the frames or bulkheads, but it's nice to see companies innovating.

 

I have signed up as a designer on Shapeways and am working very hard to get some 3D printed cannons on that site. People will say that plastic cannons are not accurate but who sees the material after they are painted? On the other hand, with 3D printing, I can add detail to make the cannons much more realistic. Once they are placed side-by-side I am sure the 3D printed cannons will be more interesting to look at than turned brass cannons. 

 

Time will tell. 

 

And now back to the drawing board (literally). 

 

Regards, 

 

Rick

[bear]

Hi Rick

 

My answer on MDF is NO WAY. Plywood is still the way to go.

Reason for this level of answer is that we have enough things to worry about health wise,and starting to use a KNOWN Cancer Causing substance in our hobby for no reason other than it would be just a couple dollars cheaper for the manufacturing of a kit is INSANE.

 

And do you see Amati passing on the lower costs-NO. I am surpised that the UE would alow MDF to be used for a hobby product.

 

With the MDF sanding dust also being a health hazzard,even if the chemicals are in "safe ranges" we do not need another possible increase in our health hazzard load as modelers.

 

Being 62 it might not be a long term risk,but who knows how long any of us will live,and have this added exposure.

 

I wish that I had not been exposed to asbestos where I worked back in the 1970's in our heat treating area,and also all of the acetone that I used to clean of Dyekem blueing off of die sections. And the paint thinners and paint in model making thru the years.

 

But now I am smarter as we all must be,and we now know what we can keep out of our lungs and eyes that can realy hurt us. This is a material that doesn't have to be used,and should not be used.

 

Now I will get off my soap box and leave it for the next builder. Plkease Rick do not go to the health dark side of kit manufaturing for just saving a small amount of dollars.

 

Keith

[rshousha]

Hi Keith, 

 

That's a wonderful note. I am sure your concerns are right. The reason I switched from plastic and ABS car models (all those Pocher models I built) is because of toxic materials. I've become allergic to CA glue and can't come near the stuff. Who knows what I ingested when I was using automotive paints on those Ferraris. 

 

So, I accept completely your concerns but I open the door to ideas on how to replace those plywood pieces with a material that doesn't warp. 

 

Actually, let's start from higher up. What can be done, in kit form, to allow new builders to build a straight and true POB model? 

 

Really, this is the crux of the matter. I want to sell a kit to a client and say "hey, you need this if you are going to build a perfect model". My new clients generally spend $400 on a model and another $200 on tools. That's the average first order. If I were to add another $150 to $200 for some sort of jig, they'd buy it. 

 

This is great; with a few emails on this forum we actually got to where we are discussing the real issue. 

 

Cheers!

 

Rick 

[Jaager]

A row or three of hardwood battens on either side of the main 'keel' piece would keep it straight.  Sort of like rider keelsons -  but much higher up. 

I am not sure how to fit this to work with the transverse 'bulkheads' - perhaps a row or three of square notches at the join with the main 'keel' with the battens fitted after the bulkheads.

[Landlubber Mike]

Rick, I built the Caldercraft Badger, which used plywood for the keel and bulkheads.  I am now building the Corel Unicorn (plywood) Amati Pegasus (MDF).  Here are my thoughts.

 

I think plywood is great, but only if it is perfectly straight.  The Badger kit came with perfect plywood parts.  The Corel Unicorn did not.  When I went to source plywood elsewhere, the package of plywood I got from Micromark was all warped (to their credit, they refunded me the purchase price), and the next source had one piece out of five in the package that was not warped.  I see people using various methods to un-warp their keel, but I have always wondered long term how successful that is if you don't also add in lots of filler blocks or other pieces to keep the keel straight - which, is a complete pain I would think.

 

MDF, at least what is used in the Pegasus, is perfectly flat and the keel, bulkheads and lower deck all fit together like a glove.  I don't know if you can get that kind of precision with plywood, and maybe Amati sources very high quality MDF.  But, it was a joy to work with.  I had to go through so much trouble with replacing the Corel Unicorn keel that it was a real relief to switch over to the Pegasus kit.  MDF is interesting too in that it is a hard material to sand, but it's quite easy to chisel as the layers flake off if you chisel them the right way.  If you chisel, you aren't creating much fine dust.

 

Toxicity is, and should always be, a concern.  I guess my take on it is that there is not much work that goes on in ship modeling with the keel and bulkheads, so your exposure is limited (I'm so slow at modeling that I'm only exposing myself every 5 or more years to the keel).  That being said, like any other time I'm sanding wood or composites, I try to be good about taking the necessary precautions of wearing a dust mask, vacuuming up the dust quickly, sanding outside if a big job, etc.  Plus, there are so many other toxic materials that are used in the hobby like woods, adhesives like CA, soldering stuff, blackening agents, etc.  So, I just try to be smart about the nature and extent of my contact with those materials.  

 

Anyway, I'm still a relative beginner to this hobby, but these are just my thoughts.

[realworkingsailor]

When I built my Pegasus, I had absolutely no trouble with the MDF.  As has been pointed out, it's perfectly flat, no warping, everything fit together and aligned cleanly. I didn't have too much trouble sanding it, mind you I did a little pre-assembly prep work with a rasp.

 

If you're worried about any kind of toxicity in the dust, just use a NIOSH rated dust mask and safety goggles. And as long as the MDF is not fresh off the factory floor, the risk of toxins being released, reduces as time goes by and the binder fully cures.

 

Also notice that MDF manufactured in Europe has very low levels of Formaldehye (per Mark's link: http://www.hse.gov.uk/woodworking/faq-mdf.htm ) 

 

To quote:

 

"Q4. How much formaldehyde is released by MDF board?

MDF boards manufactured in Europe for construction purposes must meet the appropriate European standards. These are BS EN 622-1:2003 Fibreboards-Specifications - Part 1: General requirements and BS EN 622-5:2009 Fibreboards - Specifications - Part 5: Requirements for dry process boards (MDF). There are two European formaldehyde classes, E1 and E2, depending on levels of formaldehyde emission measured. The release of formaldehyde from E1 boards is less than 0.1 ppm (parts per million) and for E2 boards it is between 0.1 ppm and 0.3 ppm.

In Europe, the majority of manufacturers produce only low emission boards.  There are some boards available on the market with extremely low formaldehyde emissions and some with ‘no added formaldehyde’, for example those using formaldehyde free binders such as PMDI, i.e. these boards will only have the naturally occurring emissions from the wood itself.  Manufacturers from outside Europe may however produce boards that have higher emissions."

At 0.1 to 0.3 parts per million, there's probably more formaldehyde in a processed-cheese sandwich.

 

As for the water issue, I had no problems with swelling when applying wet planks in fact I don't recall experiencing any swelling at all. As long as your planks are not running off like a faucet, there's not enough moisture transfer to the MDF.

 

Andy

[Landlubber Mike]

Like Andy, I had no problem with the swelling either.  I agree with him that I don't think there is enough moisture in the planks to transfer to the MDF and cause a problem.

[paul carruthers]

If worried about water ingress why not seal the edges prior to planking?

Edited April 9, 2015 by paul carruthers

[realworkingsailor]

If worried about water ingress why not seal the edges prior to planking?

 

Actually, you want the glue to wick in. It makes a far stronger bond than just having the glue bond the surface.

[Jaxboat]

MDF gives off formaldehyde. It would be trivial from the amount in a model ship. However, I would not want to laser cut the material without a substantial fume removal system. 

Best

Jaxboat

[Q A's Revenge]

The laser cutter at work had a dedicated fume extraction unit. They also used special "laser cutter MDF" whatever that is. I would imagine the burnt edges of the MDF may be quite toxic once turned into a dust by sanding but don't know if any research has been done on that particular aspect.

[grsjax]

If formaldehyde is an issue for you get the waterproof MDF, it does not contain formaldehyde.  However that said it is probable that irritation of the lungs and mucus membranes by wood dust from machineing MDF is probably a greater health hazard than formaldehyde released from the boards.  Use a dust mask and eye protection when cutting/sanding any wood product.

Edited April 10, 2015 by grsjax

[Rob Wood]

MDF is simply more dimensionally stable than plywood. There is really no argument there. The reason is that there is no grain to pull dimensionally in any particular direction. MDF is also much more finely grained than any other wood product, whether natural or man-made. I have some samples here of some incredibly super-fine details cut out of a sheet of MDF that would be impossible to obtain with plywood. 

 

Is MDF dust more toxic than plywood dust? That's debatable, but somewhat irrelevant: If model makers don't use appropriate precautions against dust when sanding or cutting any materials, they are playing with their own lifespans.

 

All of that said, I have built many, many pieces of furniture with MDF, but never a ship model. The very characteristics that make MDF attractive to kit manufacturers are potential drawbacks to kit builders, toxicity aside. MDF is much easier to split in the end grain, because there are no longitudinal fibers present to hold it together. Susceptibility to swelling when exposed at length to moisture has already been discussed.

 

On the other hand, there's something to be said for material that resists warping, as MDF does, and for the ease of cutting, shaping and sanding.

 

My 2 cents...

 

Rob

Edited April 10, 2015 by Rob Wood

[RichardG]

Maybe a better use of the MDF would be to sandwich the plywood keel after manufacturing. It seems that it's usually the keel that's warped. Assuming the plywood was flat when originally cut, a couple of pieces MDF should keep it flat until the kit is started. Or 1 piece could be solid wood to make a base (they never seem to supply that) and the other MDF. 

 

My one cents worth.

 

Richard.

[rshousha]

I appreciate all this input. From what I understand, if I can source a good MDF product, that is made to be handled safely by modellers, it should be a significant improvement over plywood. 

 

I like this, thank you. 

 

Best Regards, 

[Q A's Revenge]

Maybe a better use of the MDF would be to sandwich the plywood keel after manufacturing. It seems that it's usually the keel that's warped. Assuming the plywood was flat when originally cut, a couple of pieces MDF should keep it flat until the kit is started. Or 1 piece could be solid wood to make a base (they never seem to supply that) and the other MDF. 

 

My one cents worth.

 

Richard.

I don't know how many folks have had problems with twisted ply parts, is it a very common complaint? I can understand the frustration though when it does happen.

I think poor quality ply is probably the biggest problem although bad packaging and storage can obviously cause their own problems. Probably the best solution would be to vacuum pack the sheet parts, that would stop them twisting in storage.

 

If I bought a kit with MDF parts I'd use them as templates to cut new ones from ply wood.