Floating Head Project

[msimpson99]

I decided to write a small book on building a heavy duty floating head for plasma CNC.

It needs to be heavy duty as it will be holding my Hypertherm torch, which if you have one know that its not a small torch. Here is the prototype and it works great.

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It also needs to work with smaller lighter torches like the Everlast IP60 hand torch. Here is a small floating head I made for the Everlast torch using 8mm rails. It is too flimsy and has some other issues that will be addressed with the the heavy duty floating head.

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[msimpson99]

I will be using 12mm fully supported rails for the heavy duty floating head for a couple reasons. First the bearing trucks have preload screws so you can dial out any slop. The second reason is that they are more rigid for holding heaver torches.

Because you can't rely on the holes in linear rails the first step is to drill some new holes.

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[msimpson99]

The next step is to drill the holes in the quick change plate.

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Note that I will be using the quick change plate as an example, but you could mount the floating head on any plate as long as you can mount the rails and the switch.

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[TJS]

Nice project. Remember you are adding more weight to your gantry and it will demand more from your motors. Where did you get that template. Also you are incorporating a magnetic breakaway while you are at it aren't you. I have an older Z-car from PPLC where I adapted my own Duramax torch clamps and a magnetic breakaway. Looks like a cool project.

[msimpson99]

The template is one I created. It will be part of the book once it is complete.

The base floating head will have the torch mounts connected directly to the floating plate. I will do another project where I will build a magnetic mount with sensor switch. Kind of modular.

As for the weight, the CNC Construction Set Z axis was designed to hold large Spindles so the weight of the floating head with torch come nowhere close to give the motors issues. The torch cables are on arms (Another project) so they only add marginal weight.

The real challenge is getting the floating plate spring balanced so that you can touch off on lighter sheet metal without deflection. Note that with my Hypertherm system, I will be using an Ohmic sensor (Another Project) with the floating head as backup.

Cant do Ohmic on the Everlast torch as I cant get hold of any of the shielded consumables for the torch.

[acourtjester]

I have used a few different mounts of the torch and floating head assembly. The simplest is "V" bearing and rails, I only use the weight of the assembly as the downward force along with an ohmic sensor with the floating head switch as a safety. Attached is a template I made for the 16 MM linear slide bearing mounts on a 6" square 1/4" aluminum plate.

drilling for Center points router bearings.DXF

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center punch bearing holes.JPG

[msimpson99]

Here are a couple V rail floating heads I have built.

This first one was for my Hypertherm, mounted on my KRmx02. What you are looking at here is the full Z axis and the X carriage.

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It held up very well.

This V-rail was for my Everlast on an early CNC Construction Set prototype.

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It held up OK, but I would have adjust it from time to time to keep it moving smoothly. Mostly my fault as the Rails needed some tender loving care, and I neglected to do so before I built the thing.

The V-rail systems can be temperamental if kept fairly tight. They dont handle the plasma dust as well as the closed bearing systems. And they are generally more expensive. While you can make a very nice floating head using vgroove bearings, the 12mm bearing rails tend to be cheaper and easier to source, for this reason I decided use them in this book.

[msimpson99]

To get back on track, I have installed the quick change brackets to the quick change plate. The plate was aligned to the table and the bracket hardware tightened.

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[msimpson99]

Rails attached to main plate.

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[msimpson99]

Torch plate complete.

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Note that this plate will be used for a future magnetic plate upgrade.

[msimpson99]

Torch plate mounted and aligned.

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[msimpson99]

Switch bracket installed.

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[acourtjester]

Why not use flat headed screws to mount the aluminum plate? I bought a bag of them from eBay.

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[msimpson99]

Counter sunk screws look better for sure, but I need the adjustability. 1/4" holes, M5 screws.
If the holes are countersunk, its more work, and if one of the holes is off even by a little its a real pain to align the trucks. Most folks will most likely use a drill press to drill the holes, they will need the adjustability.

Later when I add a magnetic holder, I will use a couple of the screws as an index.

[msimpson99]

Torch Holder mounted and switch wired.

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[msimpson99]

It's time to start testing the new floating head on my CNCCS Everlast build (Pumpkin Build). I only have one plasma exhaust port in the shop so I have to do the CNCCS shuffle.

Shown here I am moving the Hypertherm build out of the way so I can get the Everlast in position to connect to the exhaust umbilical.

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[msimpson99]

Counter Weight springs installed.

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[msimpson99]

Configured and Calibrated.

I now have a working floating head on my Everlast build and my Hypertherm build.

Hypertherm cutting some parts.

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Floating head is complete. I have a Sheetcam post processor to build and a Bill of Materials to create, but thats pretty much it.