Little Plasma Cutter

[LeeWay]

Time for my next build log.
I did start a plasma build several years back, but it stalled when I no longer needed the plasma. The mill I had completed was able to keep up with production. That has long since not been the case, so this plasma is overdue really.
Instead of continuing my previous build, I will use some of the parts from it to create a smaller one. The first build was on a 5' by 10' trailer.
This new build will be a 4' by 4' machine. It will need to roll around initially, but will have it's own room with exhaust fan later.
I am also making this one much simpler than the original. While all the rollers and guides still work on the original after several years in the elements, it is really too large and heavy for a smaller machine, so scavenging parts from it.

The concept is to use 3 pieces of 80/20, which I ordered from Ebay. 1 5' 30/30.
2 6' 15/30.
Also ordered the cold rolled steel for my rails. 2- 2.5" wide and two 4" wide. One short on for Z. I still have racks from my original and have ordered all the parts needed from CNC Router Parts for the rest of the build. 4 axis motor kit and carriages, R&P drive kits, gantry uprights, rack clamps and misc. other stuff.
Bought a Hypertherm Powermax 45. A THC kit from CandCNC. While these parts are not cheap and I could have made some of this myself, I am grateful to be able to forego much of the time it would have taken. These purchases should give me a fully working machine in short order. Shooting for less than a month. The THC might take another week or two to receive but the other parts are here or on the way.
This build will require very little cutting and quite a bit of drilling. I will powdercoat all the small parts and paint the larger ones. The gantry uprights are already red, so most will be likewise.
I'll add pictures etc. as time permits.

[LeeWay]

Okay. Way too aggressive on the time expectations.

I do have most of the parts here now, save a few small items. This will be a plasma cutter to start with, but I am leaving options that can convert it to a router should the need arise. It probably won't, but good to know it can be either.

Initially on the Z axis, it will have direct drive rack and pinion as well.
I have linear slides here and ball screws that I could use, but I want to see how well the simple rack will work. This is basically a CNC Router Parts machine anyway. Should work okay for plasma.
Maybe not as well if I do make it a router later.

The main parts other than 80/20 are Unistrut parts and 2" x 3" angle iron.
All the steel will be painted black. No powder coating. The CNC Router parts look fine as is. I think they will fit better without the paint or PC.

I made the parts in the drawing different colors for clarity, but most will be black or raw aluminum. I have the zinc plated Unistrut, so it will be black and not green.

This is the initial design.
I will change and add to this as it progresses.
Let me know any thoughts or suggestions. Thanks.

[I Lean]

When I first got my table together, I noticed a fair amount of shaking when the gantry changed directions....and that's using fully-welded box tube for the table, legs, and bracing. Adding diagonal braces in all 4 vertical planes stiffened it up a TON.

My point is, I think you'll need to add similar braces--and probably some more (X shape?) under where your slats will be, to keep the whole thing square in the XY plane as well. (mine has a water table, so a piece of sheetmetal there allows no movement)

[LeeWay]

I thank you for that advice. I built a similar steel frame router that I also have on wheels, but I have to sit it on blocks to keep the gantry from rocking the whole machine. That gantry probably weighs 150 pounds. This one will be considerably less, but should be moving faster, so inertia will play a big part.
The wheels are just to move it to it's cutting location, which will be a slab in the front of the shop. It will be stored in the shop, but won't cut in there. That slab will eventually get built over and then the plasma will have it's own room.

The design is by no means complete. Just the basic frame members there and most of those are culled from my initial build on the trailer. This will have a shallow water table that can slide in the ends. Until then, I have lots of left over roofing panels that will get secured below to capture most of the hot stuff. Don't want a grass fire.

This will be done in steps and I have temporary contingencies that won't cost much.
The X bracing you mention is actually the next thing I want to add to the design. The plan is to put it on three sides.

The water tray will be designed to hold the slats. Not sure how I will make those just yet, but the water tray will be welded aluminum. I am still outsourcing plasma cut parts from a Member here, so he is probably cool with this taking longer than I wanted.

[LeeWay]

I just looked and thought some more on this layout.
I think it will benefit by putting the unistrut legs into the inside corners under the corner plates. This will allow a little more travel on the X if I extend the racks a bit. Shift them to be specific. I think my racks are 5 foot long. Haven't check them in so long, I don't recall now. I'll get that mod made as well as some bracing on the next updated images.

[LeeWay]

Just over a year later and I have made only a bit of progress on this machine.
Finally got to a point where I could start building it.
I have the basic frame together now. Some X bracing is done.
I need more, but will add that later once I start calibrating and squaring up the machine.
I will take a few pictures later as well.
Here is a drawing update.
I will forego a water table for now as well.
I can drop one in later at anytime. I have a roof over the slab now as I had intended, so pretty much out of the rain, but the gable end is still fully open and will remain that way for some time. I will build a small enclosure out there to house this machine for security and a bit more weather protection.
Anyway, the design hasn't changed much.
I did move the legs inside the frame, but not to the corners. That may change, but for now, this is how the frame is built.
Comments and suggestions are always welcome.

[LeeWay]

This is about where I am now on this.
The frame itself came out within about 1/64th inch of square. This is without any adjustments. Just as bolted together.
I think that is pretty cool.
When I get the corner plates completed, that should retain it well.
The thing about a design like this though, is that the frame really doesn't need to be square. As long as the side rails are parallel, it doesn't matter how far out the end rails are. The key to setup is to get the Y axis moving precisely 90 degrees from the X axis. Adjustable homing switches should take care of that, since it is driven on both sides.
This will be my first machine with a slave axis, so that will be a new learning experience getting that setup correctly.
Pictures still to come.

[LeeWay]

I am doing some research now for a spindle or an engraver to sit along side the plasma head on this. I will need some way of marking most of these parts.
Not sure yet which I would use, but will need one or the other. I have a HF die grinder that I could use, but thinking an engraver would be cheaper to operate and be less prone to wanting to move the material.
I do plan on some sort of a magnetic hold down of sorts to keep the sheets in position.
I will be cutting small sheets until I can get half sheets delivered.
Any thoughts, pictures, threads, links?

[LeeWay]

I have done a little research on the engravers. They are also called plate markers. Some are air scribes.
Most do basically the same thing, but there are quite a few types.
Air driven is what I see as being the most common type.
The price I saw on one of those shocked me a bit. It was $1895.00. Yeowch!

Okay it was diamond tipped but it was not gold plated.

My torch itself will run off THC, but I am thinking a spring loaded holder for a simple electric engraver might do what I need. If not that, then I am certain the die grinder would with an engraving tip.

These parts that come off this machine and will all be powdercoated, so perfection isn't needed. I just need to ID the parts after the finish.
I make maybe a thousand different parts in three different thicknesses, so I have to do something. Rather do it on the low side of $1000. Way low.

Anyone seen any of these implemented DIY? Build logs? etc? I did search and found mention of them, but no follow ups.
Thanks.

[LeeWay]

This is one of the first threads I have researched and enjoyed so far that deals with a scribe or engraver.
Great thread and build if you haven't enjoyed it yet.

http://www.cnczone.com/forums/precis...cnc_table.html

I'll add more when I get more time to do some reading.

[LeeWay]

Here are a few images so far.
Apologies on the blurred one.
I'll do better next time.

I am not sure how I will handle the Z axis just yet.
This is laid out now with CNC Router parts. In this configuration it would use a short rack.
I also have some regular slides and a ball screw that I could use, but will have to sleep on the two alternatives a bit.
I think the gear rack will be the easiest and survive the best given that this will not have a water table yet.

[LeeWay]

I was able to do a little more work on this today.
Basically just fitting up on the Z and replacing some of the steel bolts with SS. Most all of them are SS now. There are a few that aren't and won't be simply because of location in the drives. Should have done those originally, but I ain't fooling with it now. I'll swap them out if I have to do repairs at some point.

I decided to just go with R&P on the Z as well.
I had all the parts and it was extremely easy to do. I don't think Ahren had intended the parts I bought to be used like I did, but with a few shims under the Z carriages, it looks like it was designed that way.
I just stuck the rack on with some VHB tape I had on hand.
Still a little too flexy for a rack, so I will install a few 6/32 screws in it to the steel plate its against.
I'll snap a few pictures before I get it all buttoned up on the Z. Everything else drive wise is just how CNC Router Parts intended. You may spend a few extra bucks on these, but the time savings is well worth it. Or would have been if I'd had time to build it last year.

Everything is a bit tight right now. It is wearing the paint off the correct spots for the rails. I was going to mask, but just didn't see a need of it.
I'll keep some paste wax on the exposed parts. Maybe something a bit more durable.

The router I built when I first started in CNC was built similarly to this carriage design, so I know that the bearings hold up extremely well. Ahrens carriages are a heck-u-va lot nicer than the ones I made though.

I bought the MP3000 from CandCNC. Does anyone know off hand if it would still be prudent to implement a floating head?
I'll research that some more as well. I seem to have all the parts for that as well on hand. I can always lock one down if not needed.