How do you connect 8020 in a T-joint?

[pswayze]

This may seem like a silly question but how exactly do you connect 8020 pieces (or any extrusion profile for that matter). I have seen hints at a through-hole that taps into the end of the upright, and I've also seen connectors at the 8020 website that, I assume, require no holes drilled in your extrusion.


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[jsheerin]

There are lots of ways, but here's one using an 80/20 bracket:

[Amanda]

It depends on how much flex you can accept. For framing up machine guards, enclosures, etc., the standard "anchor fastener" works great. You drill a counterbore into the end of one of the pieces (7/16, I think--8020 sells end mills of the right size) which the round end of the fastener drops into, carrying a bolt that screws into a T-nut on the other piece. Quite rigid, quite square (as long as the cut end is square), and can hold a reasonable static load (the 8020 catalog has all of the stats on this). For large or dynamic loads (such as framing up a CNC gantry), the joining plates that jsheerin shows in that photo are much stronger and stiffer.

[stevespo]

There's another option as well. For the 1530 series, it's "8020 T Slot Hardware End Fasteners 15 S 3380". Available in single and double configuration. You only need to drill a small hole to provide access for an allen wrench, and tap a hole in the end of the mating piece. There's no visible sign of the fastener.

I don't know how they compare strength-wise with the T-slot anchor fasteners, but they're perhaps less work to install. For added strength, I used the end fasteners, home made joining plates and 45 degree supports.

My gantry uprights are attached this way, and the gantry "bridge" is also attached like this as well. It's difficult to see the joining plates because they're on the "hidden" side of the gantry.

Steve

[pswayze]

The situation is I have a TON of this Bosch extrusion. I only said 8020 in the thread title because thats what most people use. It is 60x60h and it only has one channel on each face. I know all the same concepts apply but the website and the connectors aren't as intuitive as looking at some of the 8020 stuff so I've been struggling a bit with it. Thanks for the input everyone.

[stevespo]

Another option that I've used, that requires no special hardware at all is to just drill a through hole in the side of the extrusion, and then create a shallow flat bottomed pocket in the outer t-slot.

Tap the end hole(s) in the mating extrusion and then tie them together with a long socket head cap screw. Depending on the depth of the pocket, the head of the cap screw may block the t-slot, but it will be recessed below the surface and present a clean appearance.

Steve

[PEU]

I used a locally manufactured extrusion system (www.micro.com.ar) Here is their explanation of the different joints, great thing about these guys is that you order and they cut and drill for you, they leave the fun part, assembly, to you




I used it for my first router


Pablo

[pswayze]

Originally Posted by PEU I used a locally manufactured extrusion system (www.micro.com.ar) Here is their explanation of the different joints, great thing about these guys is that you order and they cut and drill for you, they leave the fun part, assembly, to you I used it for my first router Pablo

Pablo, this is exactly what I was looking for. Thanks a million.

[BigBrett58]

Originally Posted by Amanda It depends on how much flex you can accept. For framing up machine guards, enclosures, etc., the standard "anchor fastener" works great. You drill a counterbore into the end of one of the pieces (7/16, I think--8020 sells end mills of the right size) which the round end of the fastener drops into, carrying a bolt that screws into a T-nut on the other piece. Quite rigid, quite square (as long as the cut end is square), and can hold a reasonable static load (the 8020 catalog has all of the stats on this). For large or dynamic loads (such as framing up a CNC gantry), the joining plates that jsheerin shows in that photo are much stronger and stiffer.

I've looked through the 8020 1000+ page catalog but could not find the ratings for the fasteners. However, I did find ratings at automation4less which showed the anchor fasteners to be 4 to 5 times as strong as joining plates. Could you give me the page number where you saw the information in the 8020 catalog?

Here is a link to the information I found (page 2):
Specs

Also, I found a place that has great prices on anchor fasteners and t-nuts for use in aluminum extrusions if you're willing to buy in quantities of 100.
T-Nutz

[stevespo]

Automation Direct is reprinting the info from the 8020 Fractional Catalog, but the catalog has some additional information in there as well, on page 40.

The numbers make sense in that the joining plates can't resist direct and cantilevered forces as well as the anchors and fasteners. At some point the nuts are going to just slide loose in the slots. On the other hand the plates are fairly good at resisting tortional (twisting) forces.

Another argument for combining them if you want the strongest frame possible. I have experienced plates sliding if you have a runaway stepper motor and no limit switches, so that is actually kind of a feature - a good way to avoid damaging your frame.

Steve

[LeeWay]

Gussets in conjunction with center hidden retaining methods create an extremely solid joint. The bigger the gusset, the more solid the joint.

[BigBrett58]

Thanks for the verification Steve. I assumed that the specs at the other site were equivalent to the 8020 info. I'm in the middle of my build and am using around 85 anchor fasteners. I bought the $60 milling bit from 8020 and used it in my drill press. It took a long time to get all the access holes drilled, but I'm very please with how well the machine came together. It's my opinion that the machine assembles very square and very rigid. At this point, I don't think gussets will be necessary, but I'll keep that in mind as a first option if the need arises. I wish I would've found that T-Nutz store earlier as I would've saved some money. Thankfully, I was able to find around 60 used anchor fasteners off of the 8020 ebay store. I also bought 25 packs of the cams and standard tnuts off from the same place. I found the socket cap screws a little cheaper through Amazon (smallparts was the supplier). For smaller quantities (<100), I recommend buying used if you can find them or buying the components. That will save quite a bit of money.