Archive for December, 2014

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Work on the homemade plasma CNC table continues to make progress. After hours of machining I finally have the Z and Y axis all mocked up and in an operating state. I often find that sometimes I need to shift gears slightly just to keep things interesting. Quite often I enjoy sneaking in side projects to break up the action a bit and keep the creative juices flowing. In the case of the plasma CNC build I was at a good stopping point to step away for a couple weeks and doing a few side jobs.

For 5 years now I have been walking into my daughter’s school to pick her up and for 5 years I have been staring at the same “remove your shoes” sign perched at the entry way asking people to do their part in keeping the school clean. The other day when I saw the sign, again, it finally dawned on me that there has to be something better and perhaps it was time for an upgrade.

The schools in my area operate on a tight budget and there is typically no money to be spent on “frivolous” items, especially “remove your shoes” signs. I talked to the principal and asked if I would be able to donate a couple of new signs that would replace the old ones. She was happy to accept the offer.

So this is where one of the side projects come in. I didn’t have a clear game plan and all the ideas I generated started to get to complicated and expensive. The one aspect I did know is that I was going to give my new shop equipment, a vinyl plotter, a workout and use it for all the art work. I decided to just head into the garage, see what metal I had laying around, and start cutting and welding.

I finally settled on a chalkboard/sandwich board retro theme. Everything was going to go black and white to give it a bit of an old school look. Since there are 2 main entrances to the school I offered to double the recipe and build two signs at the same time. As usual the documentation of the project was done in picture format and is available below for your viewing. I am happy with how they turned out and I am even happier that I completed the entire project “in house”.

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This is one of the original signs that I have been staring at for the past 5 years. Although effective, and polite, an upgrade was in order.

 

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Started by building the blank slates. I had some scrap 10 gauge mild steel so I carved out a couple chunks with the plasma torch. Starting size was 14″ x 21″.

 

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90 degrees can be boring so I bent a section of round bar to act as a plasma guide and gave the tops an appealing curve.

 

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To give the sign some depth, and to avoid sharp edges, I added some 1″ flat bar to the perimeter. It all got TIG welded into place on the back side.

 

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I didn’t know what to build for legs so I just started to bend 5/16″ cold rolled steel and eventually came up with this design. I have no pictures to showing the machining of all the mounting pegs. 2 pegs are built to support the sign and the other 2 accommodate the feet. The pegs were cut from 5/8″ cold rolled, drilled and threaded on the lathe and then cross drilled on the mill.

 

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All the support pegs were neatly TIG welded into place. I love TIGing!

 

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These are all the rough sign components that have been fabricated. I will not explain the details since the remaining pictures will clear it all up. Onto the finishing stage.

 

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The dimensions of the sign were determined by 1 thing, the size of my powder coating oven. Before I started the build I measured the oven to see what I could fit in it. It turns out a 21″ tall sign will give me approximately 1/2″ of clearance in the oven. Here I am wiring the sign to my oven rack to get it ready for the powder fogging.

 

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Sign was coated with a matte black powder coat and is now ready to get baked at 375 degrees PMT for 15 minutes.

 

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Matte black sign finished baking and hung for a cool down.

 

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The legs were coated with White Glacier Full Gloss to give them some contrast.

 

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Here the 2 blank canvasses are set to accept the artwork.

 

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Using a combination of Draftsight, Inkscape, and WinPCSIGN software I designed the main artwork. The idea was to go for a chalk board/sandwich board style design.

 

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The decals were cut out on my vinyl plotter using white vinyl. The decals were then prepped and transfer tape was applied.

 

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My daughter had requested happy faces and I didn’t want to disappoint. I sliced a couple out of yellow vinyl, they are approximately 9″ x 9″.

 

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Final product. Decals applied and legs bolted on. Clean, simple, and hopefully, and effective design.

 

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I think the white legs with the white decals was the way to go. I purchased the stainless steel feet and added a rear cross brace between the rear legs to help with stability. An interesting build fact is that I calculated the angle of the sign so that it would be perpendicular with a persons line of vision at a viewing height of 5′ 6″ from 7 feet away.

 

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The happy face satisfied my daughters request. I also figured that because the entire sign was donated I was entitled to give my blog a free plug. If the school doesn’t like it they can peel the decal off.

 

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A friend of mine sent me a link to a video that he thought I may like. Part of the reason he is a friend is because he happens to know exactly what I like. He was thoughtful enough to share with me so I thought I would share it with you.

My fascination with the garage is not always what is going on inside of it but also with the mechanicals that spill out onto the streets worldwide. For me, the following video by Giorgio Oppici demonstrates the serenity that binds people and machine together.

Giorgio Oppici was born in 1960 and since 1979 he has devoted most of his thoughts to communication. Today he lives, and works, in Valpolicella over the hills in the North of Verona, Italy. Apparently the wine is really good there.

The video was shot at the ASI Moto Show. It is the international event for classic motorcycles that has been organized for the past 13 years by ASI Automotoclub Storico Italiano. The event is held in Salsomaggiore Terme, a town and comune in northern Italy.

I could rattle on and write about all the aspects of the video that I like but I would rather you enjoy it in your own way. After all videos like this do not need explanations. Enjoy!

BTW: Thanks Doug!

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I am never short on things to fill my time with and typically I need to implement time management strategies in order to accomplish the things that I consider to be important. One of the things that suffer is the time spent on the internet looking at other cool projects people are doing. There is soooo much stuff out there that people are doing that it actually frustrates me because it inspires new ideas, and projects, that I do not have the time to take on. I am always intrigued by the blogs, and sites, that show close up photos of the actual work that is being performed and not just the finished projects. I feel as though, over time, my blog has lacked the visuals that provide the raw metal and tools. This posting I wish to get back into, what I consider, to be the passion.

For those who need an update on what is going on in the garage these days I am building a plasma torch CNC table. Check out my previous posts to get up to speed if required. This blog entry is going to deal with the Z axis. As stated previously I am building the table “backwards” and starting from the tip of the torch.

The Z axis dose have some requirements. In my case I am designing a floating torch head. For those not familiar with this style I will briefly explain. In order for the CNC software to know the vertical position of the torch head the Z axis stepper motor needs to run the torch head down until it touches metal. There are numerous ways for the software to know when the touch occurs. In my case the torch is designed to touch the work piece and then it will start to float on the Z axis. In other words the torch head stops moving once it touches metal however the Z axis continues to travel downwards until a mechanical switch is triggered. Once this switch is triggered the software can then back the Z axis upwards to a pre-programmed dimension which will set the torch head at the proper starting height. The reason for the floating design is to prevent any damaged that may occur to the torch head while being set onto the work piece. Stepper motors have enough force to start breaking components of the table and torch. By only floating the head the weight the torch head, and support plate, is being exposed to the torch itself.

I did AutoCAD some basic starting points in order to machine my main support plate. After the initial fabrication of the plate took place I started to just wing it all. The following pictures show the process I used to create a mocked up version of my Z axis. Pleased to say I hooked it up to the power supply and PC and was able to run it through its vertical motions will no issues. So at this point the Z axis is tested and working. There is still much “clean up” to do on the parts including trimming of excess aluminum. I will do this at finishing stage.

The way I post most of my pictures, for other blog entries, is in sequential order. I start from the beginning of the project and finish at the end. I changed things slightly this time. Since there are multiple smaller parts that make up the entire Z axis I tried to start certain sections with the finished part. I am hoping that it may help those, who are interested, in following along with the pictures a little better. There are 43 pictures posted in this one, most of them machining shots. If you don’t understand what’s going on I encourage you to take comfort in the visuals of 6061 aluminum, spinning tools, and flying chips.

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This is the roughed out Z axis with a floating torch head. None of the finishing details have been addressed plus much of the hardware that holds it all together is not installed. The following pictures outline some of the processes I used to build it.

 

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My arms got a work out using my manually operated draw bar to swap my tooling in and out of the milling machine. Part of the purpose of building the CNC is to give me some more “mill time” to get better at using the tooling.

 

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I AutoCAD’d the basics and then eventually got to a point where I just started winging it. This is the backing plate getting drilled and tapped according to my CAD specs. The plate is the backbone of the entire drive which will be used to support the X bearings, the X drive, and the entire Z axis floating torch head assembly. It’s built from 6″ x .375″ 6061 aluminuim.

 

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The ball screw that drives the Z axis nees to be support by 2 sealed ball bearings. Using the boring head attachment I machined a press fit hole in some 6061.

 

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Holes were drilled and tapped in order to bolt the bearing flange onto the backing plate.

 

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Next came the pressing in of the ball bearing assemblies. A vise and a socket works just fine in order to squeeze the 2 parts together.

 

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I required a coupler in order to connect my stepper motor to the ball screw. This is the final, rough machined, product. Since my ball screw shaft size differed slightly from my stepper motor shaft size I made the coupler with 2 different bore sizes on each end. The following few pictures shows the machinig of the coupler.

 

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After spinning down some 6061 solid road of aluminum on the lathe and drilling my 2 different sized holes I moved onto the mill. First step was to mill pockets to accept the heads of the socket head pinch bolts.

 

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Next the coupler was drilled and tapped for 5mm stainless steel hardware.

 

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Final step was to make it into an actual coupler by running the slitting saw through one side.

 

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Here you can get an overview of how things are starting to fit together, The bearing supports are bolted to the backing plate and the stepper motor is installed and coupled to the ball screw.

 

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Moving along I needed to build the floating head portion as well a clamp to secure the plasma torch head . A strain relief for the plasma cable also needs to be integrated. Here is a shot of what the following pictures created.

 

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The Hypertherm Powermax 45 torch head has a 1 inch diameter to clamp to. I started with a block of 2″ x 2″ x 1.5″(?) 6061 and just started milling. First step was to bore out the hole to give a nice, clean, slide fit for the torch head.

 

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The plan was to make it a pinch style clamp. Holes were drilled and tapped for 2 pinch bolts. I performed step drilling and then only tapped the bottom half of the holes.

 

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In order to allow the clamp to bolt to the floating torch head backing plate more holes were drilled and tapped.

 

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I needed to build some flex into the clamping blocking in order to ensure the torch head will clamp securely. I milled off some of the side material in order to thin the block up and allow flex.

 

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Final step was to run a slitting saw through it. The slit seperated the drilled bolt holes from the tapped holes.

 

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Next step was to fabricate some sort of strain relief to support the torch cable. No plan here, just picked up a chunk of 6061 and started to remove metal.

 

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Started on the lathe by machining the center hole to the dimensions of the torch cable OD

 

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Figured I would pretty up the holder so before I removed the part from the lathe a ran a decorative groove into it with the part off blade.

 

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Onto the milling machine. The strain relief will be secured with four 5mm stainless steel socket head screws. I milled some pockets into the clamp to accept the screw heads.

 

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Next all four holes were drilled and tapped.

 

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Time to split the strain relief in half so that the torch cable can be secured in it.

 

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A shot of the rough machining completed so far.

 

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The strain relief needs to be mounted to a top plate and therefore one side of the strain relief needs to be shorter then the other. Milled off .375″ on the rear half.

 

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More holes were drilled, and tapped, in order to allow for mounting to the suppot plate.

 

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Top plate was drilled with the same radius in order to accpet the strain relief.

 

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I have a .250″ ball nose endmill that I never use for anything. I thought I would add some useless detail to the strain relief.

 

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This is the rough machined strain relief mounted to the top support plate. I may anodize it orange, along with the torch head clamp.

 

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The following set of pictures are mostly random shots of the machining used for the remainder of the z axis. This shot is the start of the coupling block that will get bolted directly to the ball screw. This coupler will then serve as a means to connect the linear bearings to the ball screw. This is a 2″ x 2″ chunk of 6061 getting milled to make everything square.

 

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Next I roughed out an opening with a 1″ drill bit.

 

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Holes were drilled and tapped to match the bolt pattern of the ball screw nut.

 

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The roughed 1″ hole got final machined to the dimensions of the ball screw nut.

 

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Finally the coupler was milled to dimemsion in order to allow it to operate on the same plane as the linear bearings.

 

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Random shot of the coupling plate. This plate gets bolted to the coupler shown in the previous 3 pictures and then is connected to the linear bearings.

 

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I machined some UHMW (Ultra-high-molecular-weight polyethylene) to act as a slider to support the floating head plate.

 

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Once I am sure everyting is operating to spec I plan to then start trimming off excess aluminum. Here the stepper motor support plate gets a rough trim to shave of some weight.

 

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Next it gets cleaned up on the belt sander. The corner radiuses do not require precision.

 

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The next 3 shots are showing the assembled components in rough form. The stepper motors I am using are dual shaft. The motor has a different diameter shaft on each end. Since I am only using 1 shaft I decided to machine up an aluminum disc to spin on the top shaft. I will probably anodize it and sandblast a logo into it yet.

 

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Here is the side view of the floating torch head. I realize it is hard to understand the mechanics of it without more shots, video, or getting your hands on it.

 

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This is the mechanical switch I mounted in order for the software to detect the starting position of the floating torch head.

 

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It was time to clean out the mill, lathe, and the floor.

 

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Here are all the components that make up the z-axis. So far this is all just rough machined. Sill have lots of clean up to do plus the finishing.