[petruscad]

As I mentioned in my previous post everything begins with the casting of the base. And for that one needs a mold.

Attachment 269534 This is the mold fully assembled.	Attachment 269536 Here you can see the side wall anchors, the linear rail anchors at the bottom and one of the six feet.	Attachment 269538 The three brass pipes are the holes for the column mounting screws. The nuts are glued to the top of the pipes.
Attachment 269540 The steel plate in the middle is for mounting the Y-ballscrew and stepper motor.	Attachment 269542 And this is 20 feet of 5/8" reebar to be placed in the EG for strength.

The base is going to be cast upside down. That's why the six steel steel feet are mounter on the aluminum extrusions at the top of the mold and the anchors (bolts) for mounting the linear rails are at the bottom. Equally spaced anchors were placed around the mold to have places where you can mount something with a simple bolt if the need comes.

The mold is made of melamine covered particle board that's glued and bolted together. The glue is needed so the mold seals and does not leak the epoxy which is very thin.

The red interior of the mold is simply adhesive tape that happened to be red. The white areas are covered too but with white tape (no particular reason). Epoxy seeps into the wood right through the melamine layer and you get a total mess. The tape is there to form an impenetrable barrier for the epoxy. It will also be waxed prior to casting to make it easy (or easier!) to separate the mold from the casting.

The six steel pads are super glued to the aluminum extrusions and the extrusions are covered with tape to prevent epoxy from sticking to them. After solidification the extrusions can be yanked off leaving the feet inside.

The mold will most likely not survive the de-molding process. Even with tape and wax its still difficult to cleanly take these molds apart so you revert to hammers, chisels and pry bars to break it apart piece by piece. That's why it helps that the mold is made of particle board which crumples easily.

There will be two layers of reebar, two bars for each straight segment of mold. In total 10 pieces of reebar per layer.

Notice the bolts on the six feet and the Y-ballscrew plate. They are there to serve as anchors for these pieces and prevent them form ever moving of being pulled out under heavy loads.

The arrays of bolts sitting at the bottom of the mold are for mounting the linear rails. They hang at 7-8mm from the bottom so they will end up submerged by this much under the rails (the casting is upside down). The plan is then to drill through these 7-8mm of EG and them drill the bolt and tap it so the rails can be bolted down. The bolts sitting to the sides of the middle row are there for mounting alignment edges so the linear rails can be straightened out.

Oh yes, there is also a cover (not shown in pictures) that will be placed in the middle to cover those two holes.

The next steps are to prepare the aggregate and to make a vibrator to be mounted under the mold. The mold itself will be placed on two "soft" supports that will not dampen vibration.

[louieatienza]

As I mentioned in my previous post everything begins with the casting of the base. And for that one needs a mold.

Attachment 269534 This is the mold fully assembled.	Attachment 269536 Here you can see the side wall anchors, the linear rail anchors at the bottom and one of the six feet.	Attachment 269538 The three brass pipes are the holes for the column mounting screws. The nuts are glued to the top of the pipes.
Attachment 269540 The steel plate in the middle is for mounting the Y-ballscrew and stepper motor.	Attachment 269542 And this is 20 feet of 5/8" reebar to be placed in the EG for strength.

The base is going to be cast upside down. That's why the six steel steel feet are mounter on the aluminum extrusions at the top of the mold and the anchors (bolts) for mounting the linear rails are at the bottom. Equally spaced anchors were placed around the mold to have places where you can mount something with a simple bolt if the need comes.

The mold is made of melamine covered particle board that's glued and bolted together. The glue is needed so the mold seals and does not leak the epoxy which is very thin.

The red interior of the mold is simply adhesive tape that happened to be red. The white areas are covered too but with white tape (no particular reason). Epoxy seeps into the wood right through the melamine layer and you get a total mess. The tape is there to form an impenetrable barrier for the epoxy. It will also be waxed prior to casting to make it easy (or easier!) to separate the mold from the casting.

The six steel pads are super glued to the aluminum extrusions and the extrusions are covered with tape to prevent epoxy from sticking to them. After solidification the extrusions can be yanked off leaving the feet inside.

The mold will most likely not survive the de-molding process. Even with tape and wax its still difficult to cleanly take these molds apart so you revert to hammers, chisels and pry bars to break it apart piece by piece. That's why it helps that the mold is made of particle board which crumples easily.

There will be two layers of reebar, two bars for each straight segment of mold. In total 10 pieces of reebar per layer.

Notice the bolts on the six feet and the Y-ballscrew plate. They are there to serve as anchors for these pieces and prevent them form ever moving of being pulled out under heavy loads.

The arrays of bolts sitting at the bottom of the mold are for mounting the linear rails. They hang at 7-8mm from the bottom so they will end up submerged by this much under the rails (the casting is upside down). The plan is then to drill through these 7-8mm of EG and them drill the bolt and tap it so the rails can be bolted down. The bolts sitting to the sides of the middle row are there for mounting alignment edges so the linear rails can be straightened out.

Oh yes, there is also a cover (not shown in pictures) that will be placed in the middle to cover those two holes.

The next steps are to prepare the aggregate and to make a vibrator to be mounted under the mold. The mold itself will be placed on two "soft" supports that will not dampen vibration.

Cool stuff... Can't wait to see rhe pour.

For vibration, I wonder if an electric half sheet orbital sander would do, bolted to the bottom of the form..

[petruscad]

The stand is joined using the normal mortise an tenon method. Making tenons is easy, it can be done with a hand saw. Mortises in 4x6 are not so easy to do without a mortising machine. Luckily I have a Sieg mini mill which can be used as a mortiser. Here's one leg being machined.

Attachment 272830

Here are the four pieces making up one of the sides of the stand.

Attachment 272832

And here is a closeup of the joint. The top hole is where the cross beams are going to plug in.

Attachment 272834

The joints will simply be glued and clamped tight.

[louieatienza]

Haunched tenons.... Nice work!