[K_G_B]

Hi guys,
I am building a OX CNC - OpenBuilds OX CNC Machine | OpenBuilds
But have increased size of the CNC two fold so the gantry is 1m (3 feet 3⅜ inches).
It is only using 2x 20x60 v-slots for gantry and they are only fixed to gantry plates and not to each other.

I am concerned with stability and would like to glue them or join in any other way to add a bit more stability.
What are the options available to me?

• Is there a special t-nut that can connect two v-slots next to each other?
• I looked at glue for aluminium and from what I could deduct it is a big no-no, and if it is to succeed at all, I have to scrape the finished v-slot surface to even stand a chance.
• Drill a hole through both extrusions and use a screw? I only have 3mm (0.118 inches) from side of extrusions to z plate so I would have to run a screw through one of the channels on extrusion sides (seems a bit impractical, honestly)

Once I am up and running I can create new gantry plates that can accommodate 20x80 extrusions and that can potentially solve my issue?
Or maybe even add a third extrusion?

Let me know if I'm not making any sense.

Regards,
Milo

[ger21]

You could try gluing them with a good quality, 100% acrylic caulk. It won't be a rigid glue line, but silicone caulk bonds pretty good if the surfaces are really clean (clean with alcohol). As a temporary fix, it should make it quite a bit more rigid.

[DiggerJ]

There are connector plans to 3d print on the Open Builds site, that are used to hold the extrusions together. JB weld should also work well on clean surfaces.

[wizard]

A picture would help here.

Are you suggesting that you have the two extrusions sitting on top of each other? If so are there tee slots in alignment with each other. If so the common way to do this is to put a tee nut in one channel and about in the other and screw them together. This requires the use of a drill to punch holes into one channel to align with the Allen socket in the bolts. The bolts may need to be button heads or an alternative profile to standard cap and you will likely want to use washer that may need to be modified.

Another option is simply to bolt joining plates to the fact side of the extrusions.

To supplement what ever bolting approach you use you could slather Loctite on the two extrusions where they will come into contact with each other. Loctite is effectively a glue and will add some strength. The big problem with most extrusions though is that they are anodized and that process usually leaves a sealer on the surface. This sealer makes it very difficult for glues to get a grip. You might talk to the manufacture to see if they have a recommendation for removal of that sealer. Removal of that sealer though may leave your extrusions looking rather ugly.

If you really thing that you need to bolt the two extrusions together another extremely simple approach is to buy some long bolts. You may need to make up some nuts and washers so that the bolts tighten against the inner profile and not the outer flanges of the extrusions. I've seen examples where extrusions get bolted to other frame members with through bolts that sit in pockets cut with an end mill. Effectively the extrusion gets counter bored so that the cap can bear against the inner parts of the extrusion aon not the flanges. One alternate to counter boring is to bolt through the extrusion with a large backing plate for the bolts cap that spreads the load over the width of the extrusion. In the end what you can do is somewhat dependent upon the extrusions design, I just hinted at a few common choices above.