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Permalink Reply by Earnest Fontenot on January 20, 2014 at 11:06am

Gaston,

I've used 3/4" MDF so far.  Haven't had any problems with it.

I've made the rudder and am now making horizontal stabilizer parts. I made the (6) 6T1-2 Center Ribs over the weekend and the MDF held up just fine.

You're not making a huge number of parts with each block so not a lot of wear and tear.

My $0.02.

Earnie

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Permalink Reply by Doug MacDonald on January 20, 2014 at 11:43am

I used 3/4 inch plywood for the form blocks for my 701 and the blocks worked well.  I'm planning on scratch building a Cruzer next and will likely use plywood again but only because I have a bunch of scraps I got for free.  If I had to buy the material I would likely use MDF.

Doug M

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Permalink Reply by Jesse Hartman on January 20, 2014 at 12:25pm

I agree

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Permalink Reply by Henri Luyckx on January 20, 2014 at 1:46pm

I bought the Scratch Building Basics for Metal Aircraft DVD from homebuildhelp.com and got to know everything there was to know about form blocks, forming ribs, cutting and bending sheet metal and more in about 45 minutes :-)

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Permalink Reply by Doug MacDonald on January 20, 2014 at 2:17pm

Yes, Mark and David did a fantastic job on the Scratch Building Basics for Metal Aircraft video for Jon.  I recommend it even for those who are kit building as it gives you the confidence to replace a part if you make a mistake.

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Permalink Reply by Gaston Brawley on January 20, 2014 at 4:04pm

Thanks for all your replies.  I have a lot of scrap 3/4 inch plywood, and will use it for making the forms...

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Permalink Reply by Carlos Sa on January 20, 2014 at 5:56pm

In case you have no luck w/ plywood: I used MDF, and applied two coats of varathane.

I suspect that without the varathane the MDF would not take the pounding well...

Good luck

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Permalink Reply by Earnest Fontenot on January 21, 2014 at 6:55am

Carlos,

I do not apply anything to the MDF and it holds up more than adequately for what needs to be done.

Give it a try without the varathane.

Earnie

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Permalink Reply by Gaston Brawley on January 21, 2014 at 2:47pm

Thanks, I am reconfiguring my basement, building some additional benches and moving tools around.  I really liked how you mounted the vice to the plywood so it could be moved around. I am definitely going to use that idea....

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Permalink Reply by Earnest Fontenot on January 21, 2014 at 5:20pm

I've had to make things modular and mobile for my workspace. I'm using my garage but need to be able to still park our cars there.

I'm glad one of my pictures gave you something that you could use!

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Permalink Reply by Tim Smart on January 21, 2014 at 1:01pm

Gaston,  

I used 3/4" MDF for my CH650 forms except for the nose ribs, for them I used plywood but laminated 1/8" aluminum to the form so I could really work on the nose area and because of the amount of ribs I had to make with that form.  For the CH750 I just used plywood that I had, either material should be fine.  I did not seal my MDF forms with anything but made each form and then the ribs for that form as I did not know if expansion of contraction with humidity changes might occur.  

One note of caution, sawing, sanding MDF CREATES a LOT OF DUST.  I used a paper dust mask when building the forms

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