[WereWoof]

Howdy all!

Thought I would toss this out there in case anyone else wanted to build a simple breakaway torch setup.

We have a plasma table that carries a Hypertherm T80M machine torch. In the past we have had it catch on a few things, but not badly, so of course I ignored the problem in typical human nature. Well, last week, my partner was jogging the beam in the y axis and got the torch tip caught on a piece of plate on the water table.. as has happened to many, it snapped the fiberglass/plastic housing of the torch. GRRRRRRR.... Of course, then 20-20 hindsight set in so I decided to remedy the problem. In looking through the forum I came across an idea for a magnetic breakaway fixture for the torch to prevent this type of damage. It sounded like a very good idea so I modified our setup to use that concept.

On our tool mounting system there is a vertical plate, that carries the torch. Two split clamps are fastened to the plate (formerly) by way of a single screw through the plate and into the back of the clamp. I decided that it would be easiest to modify the components at this point to break away.

Included here are some photos annotated to show the modifications done, and the way that it works. It was decided that 4 pair of NIB rare earth magnets would be strong enough to provide adequate grip to support the torch, but weak enough to allow the torch to break away easily if crashed. These magnets are .375 inches in diameter and .125 inches thick. They are available from many sources. I just ordered 150 of them for another project so had them in stock already. Our cost was 20 cents each, delivered.

To do the modification, I removed the clamps from the tool/torch holder plate first. I then located and drilled 4 holes in the tool holder plate at the desired locations. Next, 4 of the magets were coated with loctite retaining compound (to hold them permanently in place) and pressed into the drilled recesses.

In photo 4, the red arrows with the letter "D" show how the magnets were set into the tool holder plate. In between the magnets, letter "E" and arrow is pointing to a countersunk hole centered in the plate. This hole is critical to the system. If just magnets were used to clamp the torch to the tool plate, the torch clamps might slide around even though the magnets are stuck together and cause inaccuracies in cutting. I needed something to "center" the clamps in a very accurate location on the tool plate while the magnets held it clamped there. That countersunk hole provides a "socket" location to do just that.

In the photo 6, that picture shows the clamps located in position on the Hypertherm torch. the Letter "B" and arrows point to the NIB rare earth magnets that I set into the torch clamps. These magnets are set at the same vertical spacing as the magets in the tool holder plate, so they match up face to face. I should note, that the magnetic North - South faces must be correctly oriented when you install the magnets so that the opposite poles of the magnets in the tool holder plate and in the torch clamps attract each other when the clamps are in position.

The red letter "A" and arrow indicate a 1/4-20 socket button head cap screw that I installed into the clamp face. This button head screw exactly fits into the countersunk recess shown in the photo "torch mount 4". I took care to countersink the hole just deep enough so that when the torch clamp is mated exactly tightly to the tool holder plate, the button head on the screw exactly locates the clamp in position. While holding the clamp in postion, being a rounded button head, it still allows the screw to break away, even if the torch is crashed while moving sideways. If I had used straight shank pins they would have allowed the torch to break away while moving forward and back, but might have gotten hung up if the torch crashed while moving sideways. Using the countersunk hole and the button head screw insures that this doesen't happen.

Overall, this modification took only a short time to do - less than a couple hours- and seems to work perfectly. In the picture Torch Mount 2, you can see a single bolt that is in place at the very top of the tool mount plate to support the torch hose. After this picture was taken, I added a matching bolt on the other side of the torch hose to provide support on the other side. Before the breakaway torch mods, I used to have a clamp that fastened into the bolt hole to tightly secure the torch hose at the top of the tool plate, but with the breakaway torch mods, the torch hose as well needs to break free in order for the system to work properly. This picture also shows the torch as held in place by the magnets. It takes a pull of several pounds to pull the torch off of the tool holder plate.

Good luck with your projects and thanks for providing great ideas!

Dave




In the p

[bobsch]

Very nice solution!

[WSS]

Great idea! The socket/detent is critical for repeatability. I use a dual breakaway set-up for ours and really need to add a location system. For oxy it works fine but when the plasma finds the plate it can shift and cause all kinds of trouble.

Nice work.

WSS

[jimcolt]

Here is my breakaway for use with a Hypertherm Powermax45 machine torch on a PlasmaCam machine.

Jim Colt

[Bigrhamr]

Really nice simple and low cost solution, thanks for posting it.

I assume if the torch hits somethings while cutting and pops loose the machine will get a lost arc signal and stop motion. Is there anything else to consider for that aspect of the breakaway mount? Any way to automatically stop it under rapid travel?

[WereWoof]

Nice work on the breakaway, Jim! Thanks for the magnet idea too.


>>>"I assume if the torch hits somethings while cutting and pops loose the machine will get a lost arc signal and stop motion. Is there anything else to consider for that aspect of the breakaway mount? Any way to automatically stop it under rapid travel?"


I dont see any reason that one could not mount a small micro switch so that the torch in running position keeps the switch "made" and tied into the E-stop or limit circuit so that if the torch hit something and popped off, it would kill all motion and the "plasma on" signal as well. Thats a good idea. Thank you for bringing that up and suggesting it. I will haftoo add that this weekend.

Best wishes all!

dave