New Material for MFT tops, HDPE

[woodshopdemos]

Hey Eiji - off topic, but since you brought up the problem of your eyes adjusting when you go from inside to outside on a sunny day, you might consider doing what the pirates did: wear an eyepatch! The eye patch will stop one eye from adjusting to the bright sun so that when you go inside, you just lift it up, and presto - you can see! Pre-adjusted for the dim light. It really works. I saw it on Mythbusters, so it must be true!

Poto

P.S. Bet I'm the only person in Hong Kong right now wearing a Rotex anniversary Festool watch!

I think you can take eye patch many steps further: one eye can be used for metric and the other imperial.

As to the MDF, plastics HDPE, Formica, or any other top, it seems to me a lot of work and expense to improve a product that is pretty damn good as it comes out of the box. Do keep in mind that if you add any thickness at all, the Festool clamps may not work. Of all the suggestions, I like the paste wax one best...or shellac from a spray can. I use both on my jigs -- shellac and then wax.

 

[poto]

I think you can take eye patch many steps further: one eye can be used for metric and the other imperial.

Hey John - great idea. I tried it, but whenever I worked in Imperial, I kept walking into things! 

 

[honeydoman]

Try applying a coat of silicone free wax to the surface of your mft, it will resist glue and spills.  Works great for me, just allow it to dry for a day or two.

where do you get silcone free wax?  is it the one that min- wax makes?  thanks, and that sounds like a great idea!

 

[woodshopdemos]

Simonize, I thnk.

 

[Rescue U]

Sorry for the delay! I used Mylands wax on my mft top.  There are several other silicone free waxes on the market as well.  Check Woodcraft.com.

 

[Dave Ronyak]

I've been thinking about making a MFT top out of phenolic plywood.  Glue is easily removed from phenolic and you can get a 3/4 in sheet
for about $70.

~mark

Phenolic faced plywood is available in full inch thickness with a baltic birch core that is void free, but that extra thickness might interfere with insertion/removal of Festool's clamps.  Woodpecker sells it occasionally.  They and others recommend it wherever dimensionally stability is needed, wear resistance and glue resistance is desired.  It is also recommended for clamping cauls and pads due to ease of glue removal. 

Dave R.

 

[Mark Carlson]

I was thinking of using 3/4 phenolic plywood.

 

[Warrior]

using 1" material for an MFT top is no problem. just chmfer the holes after drilling. I have a 1" mdf top for my large MFT.

Eiji

 

[Warrior]

The top is going to have to wait a lil bit. I cant seem to stop spending money on tools long enough to buy it. ;D

 

[Dave Ronyak]

Les,
Applying poly to the MDF top is time consuming considering getting the poly onto the surfaces in the holes as well. Also the end grain of the MDF is so porous that it is hard to seal.

I havent given the tolerances that much thought since all the holes would be drilled out on a CNC guided router. I just assumed that it would be accurate with a CNC but I will find out what the tolerances are. I do need to figure out if the top will sag or distort with temperature differences. I know that my MDF top moves a lot if I am in a sunny area and want to cup. I just flip it over and it flattens out and starts to cup again as the top side gets hot in the sun and the underside stays cool. Sorry for the run on sentence but you know what I mean. This is never an issue inside regardless of humidity. I would have to think (but I'm not sure) that this would be less of a problem with a white plastic top. Maybe I should just always set up in the shade. I just hate going out side in the sun to cut just after being inside installing or visa versa. Making my eyes have to readjust all the time drives me nuts.

Eiji,

Before making the plunge into a plastic top, ask your supplier for some scrap material and test it to see if your likely to experience unacceptable distortion from flat plane due to hot sunlight exposure.  I haven't checked the coefficient of thermal expansion of  HDPE, but I know that of some other common plastic materials is rather high, e.g. PVC.

You did not say which way the MFT top distorts when exposed to the hot sunlight.  If the upside exposed to the sunlight becomes convex (center higher than the edges), the upper surface is expanding more than the lower surface.  But if the upper side becomes concave (center lower than edges), then you are more likely experiencing the effects of a slight difference in moisture levels between the upper surface (reduced moisture and thus shrunken) and the lower surface (higher moisture and not shrunken).  It is the differences between the upper and lower surfaces of the MFT top that cause it to distort, changing the ambient moisture doesn't change the moisture level between the top and bottom surfaces of the MFT, unless only one of those surfaces is sealed.

Dave R.