[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]

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]

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

[sdantonio]

I checked on it, the stuff is called 1050

[Treischl]

I finished up my t-slots this morning. Not too bad. Pics



Closeup:



It is a striped looking because the parts were cut from two different pieces of MDF. All I did was rabbet the edges to fit the t-nuts. Then screw the whole thing down. What I did notice is that the two different MDF's are a bit different in thickness too. I was planning on taking a skim cut anyhow and then sealing it off with shellac, followed by a light sanding to restore some friction on the surface.

I guess a guy could do what I did, then slide those aluminum tracks in and screw them down too. Hmmm. Best of both worlds? I am not big into buying stuff if I can make it myself. Obviously, I am building a machine!

Lots of good ideas here, that is for sure.

[sdantonio]

Very nice job. I'll keep you solution in mind when I get that far.

[JerryFlyGuy]

Well, at the end of the day, I'm back where I started. sorta..

I really like these slots you've done Treischl, and I think this is how I'm going to do mine. It mean's that I can change the thickness's of my sheets a bit. I'll get 3/4" fixed base, w/ a 5/8" on top of that. The 5/8" will get the 3/4" x 1/4" deep grooves milled into it, then I'll screw and glue down a 1/4 [or possibly 3/8] plywood on top of that and remill the grooves at 1/4" [or so] to form the 'T' slot. Then I plan to plane off the top surface and paint it to help keep the moisture out of it all.. It should work until I get my steel and Extruded Alum 't' slot table ordered.

The blind nut's were going to cost $20/hundred and I needed 2500 of them.. so that was as much money as the alum insert slots. I'll still check at Home Depot tonight for the alum inserts but if I don't find them.. this is what I'll build instead.. it's by far the cheapest route.

thanks again guy's

Jerry

[sdantonio]

Jerry,

If you do decide to go the aluminum insert route 80/20 garage sale (their ebay site) has the 1050 stock at $8 per 4ft length. You may want to hurry, they only have 295 pieces left and demany will be high... operators are standing by.

But I do like Treischl solution too, and when the top gets worn you can rout it off and put on new pieces.

[JerryFlyGuy]

Jerry,
when the top gets worn you can rout it off and put on new pieces.

This is the main reason that I like it, it's so blame cheap that the other solution's can't compare. The worst part of it is having to unscrew the top strips of plywood. I figure if I can do this for just the cost of the plywood and screw's I'm laughing. I can save my money to cover the cost of the final table when it comes time to build it.
The down side is that there is going to by the swelling and shrinking of the plywood, but for now.. thats un-avoidable so I'll just have to live with it. I'm hoping that it won't be needed for more than a couple months before I upgrade to the steel/alum table. My machine is 20 x 10 [feet] so cost is a consideration for sure..

Jerry

[sdantonio]

My machine is 20 x 10 [feet] so cost is a consideration for sure..

Jerry

Wohhh, and I thought mine was big at 6 X 3 (ft)

[Madclicker]

My t-track is mounted in the permanent base of my machine and was never intended to hold parts for cutting. That's what spoil boards are for. It holds the spoil boards, vacuum table and fixtures and allows easy switching between the various things I use to hold my parts and panels.

After using my vacuum table for the last few months, I know a vacuum system will be the center of my full sheet machine.