T slots in MDF??

[JerryFlyGuy]

I remember recently seeing someone with t slots in MDF. I'm wondering if this is common practice and if so, how much force can a person count on getting out of the slot? I was thinking of using blind nuts for my system but am curious as to what others are doing to tie their parts down to the bed of their mills etc..

Jerry

[Treischl]

Hi Jerry.

Actually, machining them in is not the best way, imho. As for holding a hex head bolt, that may not work too good either. But what does work is this:

Take a 3/4 piece of mdf, rout slots in it for toilet bolts (they have nice big flanges compared to hex head bolts. Then, glue down 1/4 inch MDF strips to create the T slot shape. Very strong! And cheap!

Hope this helps ya out. I am going to be doing that to the table I am building.

http://www.cnczone.com/forums/showthread.php?t=33124

[JerryFlyGuy]

Hrrm.. so what your saying is to use carriage head bolts and screw/glue down strip's of 1/4" plywood. You'd need two strip's per 't' a narrow one and then a wider one on top? This might work... I'm starting to wonder however, if I just used the machine and drilled a hole on 3-4" centers through out the working surface and put a blind nut in the hole, then turned the sheet over and screwed it down [I'm using a 3/4" base sheet with a 3/4" top sheet screwed to it] that I'd have a workable solution? This really just a temporary solution until I see how the machine works and I make a few buck's on it. Then I'll upgrade it to a 3/8" 44w base plate w/ Extruded T slot Alum bedding on top of that.. in the long run it'll be better but for now.. I just want a base which will get me going..

Thanks

Jerry

[Treischl]

Sorry, not carriage head bolts. Hardware stores carry a bolt called a toilet flange bolt, it is basically a t-shape. You can find them at places like Rockler or Woodcraft too. Here is a pic:



The toilet bolt is the thing on the right. You can see how it will not spin in the slot. Also, you do not have to rout a very deep slot, since the flange is not real thick. Hope this helps some, it is fast, easy and cheap!

On some of my fixtures, when the 1/4 top gets chewed up a bit, I just add another 1/4 strip over the top of the first. You can usually do this a few times!

[NEATman]

How about just using these aluminum inserts?

http://www.rockler.com/product.cfm?O...Select=Reviews

NEATman

[Madclicker]

I use this:

http://www.hartvilletool.com/product/11036

You get discounts for 4 or more. $7.50 ea for 36".

[Treischl]

Yup, the Rockler and Hartville stuff is good. The only trouble I have had using those things is if you set the track just a bit below the top surface. When clamp pressure is applied it wants to rip those screws out, especially if MDF is the base material. The other thing is if one accidentally cuts a bit too deep, it sort of ruins things. Oh, one other thing, by the time you cut the slots for the aluminum channel, there is not much left to sink those screws into in the first place. So, you have to use thicker material which cuts down on Z clearance.

I am trying a new idea this morning, since this whole thing got me to thinking at 4 AM. I will post a pic over on my thread when I am done. Essentially, I am going to put brass inserts into some hardwood. Then cut them so they are rectangular (to stop the spinning and give a good surface grip area. Then it is just a matter of making the T strips and fastening them to the sub top.

[JerryFlyGuy]

That stuff looks pretty impressive.. I suppose if a fella put it far enough below 'grade' you would have some room to still face off your table if/when needed as well.. and then only replace it when needed. I'm using two layers of 3/4" plywood so those 'Hart Design' unit's would probably do the trick fairlywell.. I'd have to route a notch.. 3/4" x 5/8" which would give me 1/8" backing and it would be 1/4" below 'grade'. Then the screw would hold the top plywood sheet down to the one below as well.. hrrrmm.. this has some potential..

Now the only problem is.. if I put one every foot across my table.. and down the length.. I'd only need..54pc's of the 36" length's to do my machine.. ~$500.. thats not the end of the world I guess..I'm going to have to check out Home-depot to see if maybe they have something similar to this right in the store..

Thank's guy's..it gives me some things to think about...

Jerry

[CJL5585]

I am using the Rockler units shown in post 5 by NEATman. I used 3/4 inch MDF, routed a slot 3/4 inches wide and 1/2 inches deep, installed the aluminum rails. Works very well.

[bryanrabb]

I used the t-track on my model A. I had another piece of 1/2 MDF below the first 3/4 piece. THat gave it more rigidity and more material to bite into.

[Wun Fungi]

Originally Posted by JerryFlyGuy I remember recently seeing someone with t slots in MDF.

Here's a design that uses Slotwall: http://chuckknight.bravehost.com/router/router.html

It's not hard to find: http://www.slatwall.nu/

The grooves are on 3" centers. And you can get aluminum inserts that significantly add to the strength.

Steve in NM

[sdantonio]

Originally Posted by NEATman How about just using these aluminum inserts? http://www.rockler.com/product.cfm?O...Select=Reviews NEATman

You must be able to buy this stuff as aluminum stock somewhere and cut out rockler and the expensive middleman. How about something from 8020, they must have something in the 1"x 0.5" range with matching bolts