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XYZ Gantry Build with Rotary Axis
I’ve decided to go ahead and post a build log of this project.
Yes, it is another XYZ Gantry Kit.
Yes, it is another aluminum extrusion frame.
But, it is going to have a fourth (rotary) axis AND I don’t know what the hell I’m doing so my struggles may prove interesting and I’m sure likely to need some advice along the way.
A few things before we get started. I did do some design work in a 3d Cad package. I have never really used one before so there is quite a learning curve here. In the end the CAD design is rough. Knowing what I know now, if I had time to redesign it from scratch it would be much more complete and useful.
I built an MDF design a couple of years ago using Rockliff plans. It used acme threaded rod, Delrin nuts and assorted styles of linear rails. It is a moving table design with a cutting area appox. 18 X 18. It actually worked (works) albeit with limitations due to parts selection and some alignment issues. Still, had a great time doing it and learned a bit.
Anyhow, I’ve wanted to do a second machine for quite a while, always with the intent of including a rotary axis. When I started to seriously think about what to build I ran across the XYZ Gantry web site. Seemed like a good way to jumpstart the build by having all the mechanicals supplied in one package. I know this may not appeal to a lot of you as there is a lot to be said for picking your own components, assembled and designed to fit your exact requirements. But I am more interested in using it and not spending what would be for me, a long time struggling with the design (due to my limited knowledge) and the build (due to my very limited skills). I have never done any work in metal and all of my tools are woodworking tools.
So here is a screen capture of what I’m shooting for from Alibre. It is NOT a fully fleshed out design. Its main purpose at the time was to be able to order my extrusions. The rotary axis design is really sketchy and subject to change (much more on that later).
There is going to be a lot of bumps in this road but hopefully (with your help) it will eventually all work out.
Thanks for reading and I am way open to suggestions/questions as I go so please feel free.
BobL.
What I’ve got…What I need
I’ve got a lot of the components picked, ordered and in hand. But there is a lot I am lacking at this point. As much as I want this to be a quick build it will be going on for a while.
What I have:
Main mechanical components: Obviously the XYZ Gantry kit from PBC Linear. I ordered it with a 24” X 48” cutting area due to lack of space. I would have loved to have a 48” X 48”.
Frame: I’m using Misumi 8 Series 4080 extrusions. Misumi is running a first time order special. You can get up to 150 dollars back on your first order. I think the way it works is they give you a credit 30 days after your first qualifying order. Hopefully I’ll ‘qualify’ and get that rebate.
In fact, my orginal intent was to place my initial order and then get additional items I needed using the rebate. I spent so much time screwing around with the CAD program and debating part selection that I didn’t place my extrusion order until recently.
Motors: The main build requires 3 Nema34 and 1 Nema23 motors. I ordered 3 640 oz/in motors from Keling and have a new 425 oz/in Nema 23 motor left over from my original build (a rotary that never happened).
Drivers: I’ve got 4 Geko G213V’s :D
Power Supply: I’ve got a 50 volt, 20 amp PS from Keling.
Electronics: I’ve got PMDX-126 breakout board and a PMDX-134 board to plug the Gekos into.
Spindle: My original plan was/is to use a PC 890 router with some precision collets controlled by a SuperPID speed controller. I have the SuperPID but have not purchased the PC 890.
I did notice that the router bracket I ordered will also fit a Dewalt 618 (of which I have two). I ordered an extra sensor for the SuperPID but haven’t decided if I want to modify one of my 618’s or not. I really want to end up with the PC 890 but we’ll see.
Rotary Axis: We will get into this in much more detail later, but for now I will say I have a new Phase II 6” rotary table I plan on adding one of the 425 oz /in motors from my current machine to. I’ve also got a ½” slab of 7075 aluminum and some used linear rails.
What I need:
More T-nuts for starters. I ordered two hundred pre-assembly economy T-nuts. Who knew they would go so fast.
I’ve got the caster/leveler feet but need to fabricate a mounting plate to attach them to the frame. This is going to be interesting, my first foray into metal work.
I have yet to design the layout for the electronics and have not ordered practically any support electronics as I don’t know what I need yet. This is going to delay the build considerably.
The design of the rotary needs some serious thought.
Pictures in the next post.
BobL.
It seems from your drawing
that the spindle only reaches to the mid-point of the rotary axis. Having done a bit of this sort of work, I'd suggest you design it to reach the far edge of whatever the largest workpiece is that will fit in the rotary axis space. It's a lot quicker to rough something out of a rectangular piece of stock if you can get all the way around it, then rotate it 180 degrees and cut the other side. After that, you can usually run a finish pass with the Y axis fixed at the center of the rotary axis, but not always - it's good to be able to do the whole part in indexing mode.
Andrew Werby
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