# CNC Plasma Cutting When You Have No Space



## Tmate (Aug 6, 2020)

While we would all like to have the space in our shop for a 4' x 8' or larger CNC plasma table, exhaust system, etc., many of us do not.  Still, we should not deny ourselves such a fabulous, time saving process just because we don't have the ideal location for it.

I solved this problem years ago with a 2' x 2' table I could roll out of my garage in a couple of minutes to cut a shape.  Besides eliminating the normal space requirements, this also solves the dilemma of how to deal with plasma dust.  Get 8 to 10 feet or so outside and the problem goes away.  I was doing prototype work out of my home at that time, and the parts for virtually every bracket I needed could be cut on this small machine.  When the business grew and we moved to a commercial facility, the CNC electronics and motors were simply transferred to a larger table.

I'm retired now, and recently built a similar 2' x 2' machine.  This one I keep outside under my deck under a vinyl fire pit cover.  The compressor and plasma cutter are just inside the basement door, 10 feet away.  It takes 5 minutes to hook up the cables and mount the torch.  In the winter I remove the gantry and gear racks and bring them inside.  There is no reason it couldn't remain intact and used in the winter.  I just don't choose to do so.

The first picture shows the initial machine that was on casters and rolled out of my garage.  The second is my current machine.

If anyone is interested, I can post photos of some of the parts and shapes cut with this little machine, none of which are for sale.


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## JimDawson (Aug 6, 2020)

Nice build!  We would be very interested in seeing all of the details.   And your parts.

What are you using for a torch height control?


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## Tmate (Aug 6, 2020)

Not withstanding all the hype one hears about the need for a height control, they don't work well on this sized machine.  I have one, but took it off.  Their main advantages are greater consumables longevity and ability to handle large warped plates, diamond plate, etc.  On a low production machine of this size, consumables life is a non issue, as is plate warpage.  I use a rack and pinion torch holder.  The height control sits on a shelf.

Below is the current machine with an arc voltage height control.

I'll post some more pictures shortly.


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## Tmate (Aug 6, 2020)

Here are a few photos of shapes cut with the 2' x 2' machine.  None were done with the height control.


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## Papa Charlie (Aug 6, 2020)

Did you build you own unit or purchase?
I would love to have a unit that size. What do you recommend for a starter?
Thanks
Patrick


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## Tmate (Aug 6, 2020)

I built it.  The table build is simplicity itself.  I would be happy to share the specifics if there is interest.  The CNC electronics & software are a separate matter.  There are dozens of sources for that in all price ranges.  You don't need a torch height control, which is a big savings.


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## Papa Charlie (Aug 6, 2020)

I for one would be interested in all the information. I have very little knowledge of the CNC side of it. So any and everything you are willing to share would be greatly appreciated.
Patrick


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## Aukai (Aug 6, 2020)

I'm digging the gasser 
I have a Certiflat plasma table, and a Miller 45 XP, but the CNC stuff looks to be in the 2K range?


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## Tmate (Aug 6, 2020)

I am using a Hypertherm 45XP plasma cutter with a machine torch, a Speedaire (10.7 cfm @ 90psi) compressor, and FlashcutCNC electronics and driver software, and a Bugo torch holder.  I use CorelDraw to draw the shapes and create the dxf files used by the driver software.

I have been using Flashcut for years, and have no idea what their entry level pricing might be now.  Their software is great.  Other possibilities include Torchmate, cncrouterparts.com, Microkinetics, CNC Router Source, and a number of others.  Some will want to sell you the table along with the electronics.  You are looking for a retrofit kit.  It's much cheaper to build a superior table of this size yourself.  A great source for CNC information is cnczone.com.

My recommendation is to build your own table while you learn what is available in the way of CNC controls that meets your requirements and budget.  The table  includes everything right down to and including the mounting brackets for standard Nema 23 stepper motors.  Whatever electronics package you buy will include the motors and everything beyond.  In other words, no matter whose electronics you buy their Nema 23 motors will bolt right up.  The number of parts you have to fabricate yourself are minimal, as the table uses off-the-shelf components wherever possible.

I took pictures during my latest build, and still have the files around here somewhere.  I also have a list of all the components, where I got them, and in most cases the part numbers.  II'll try to dig that stuff up if anyone is interested.

You will probably have something like $3K involved by the time you are through, but it is well worth it.  There is absolutely no way to reasonably do the same kinds of operations with machine tools.  A bracket that would take an hour to cut out with a hand torch and grind the edges takes about 30 seconds or so with CNC plasma.


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## brino (Aug 6, 2020)

Tmate said:


> I would be happy to share the specifics if there is interest.





Tmate said:


> I'll try to dig that stuff up if anyone is interested.



Oh boy, oh boy, oh boy!
Yes, please!

I am nearing the end of cutting about 40 brackets with plasma by hand.
Speed makes such a difference in kerf width I am having to grind/sand the edges to clean-up.
Very slow going.

Any wisdom that you can share is greatly appreciated.

-brino


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## pontiac428 (Aug 6, 2020)

I like how the small size is the solution to torch height control.  For me, brackets and tabs and other automotive stuff would be the immediate purpose.  Most of that stuff fits fine into a 2'x2' envelope.  Hmmm...

My plasma is a Thermal Dynamics Stack Pak with two power packs.  I have a 35a torch head and a 70a torch head.  I do have a straight torch for automated application, but I need to do some homework on the Thermal Dynamics as to why the rep told me it wouldn't work with CNC.  I think it had something to do with latching with the control.  Don't know why it wouldn't work with the control boards out there.  

I'm also sitting on a box of PMDX boards and Gecko drives... Yep, might have a project in my future.


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## Tmate (Aug 6, 2020)

I am going to present this in increments, rather than wait until I pull all the information together before sharing it.  The table is as follows:
https://www.rockler.com/rockler-24-x-36-shop-stand under part no. 48089.  It is normally priced at $149.95, but is on sale now for $119.99.  It is quite sturdy, and is the perfect dimension for the project.

When you have finished assembling the Rockler table, enlarge the three holes in the top of each 24” end to 1/4”.

You will assemble the 33 1/2” x 36” framework shown below from 8020 aluminum extrusions. You can purchase these extrusions off the Internet in 36” lengths or cut to exact length. The 8 hole angle brackets and fasters can be ordered at the same time. Note that there are 4 additional angle brackets underneath each corner, which cannot be seen in this overhead view.

Note that the table as shown here, uses Origa (Parker) FD25 linear rails and roller cassettes.  These are quite expensive and difficult to come by if ordered new.  I purchased mine off eBay at a reasonable cost - maybe $250 for both rails and cassettes.  There are a lot of smaller FD-12 and FD 15 sizes on eBay, and a few FD-20s, which would probably work if the brackets were downsized a bit.

I have ordered the rails and cassettes new from RS Components in the UK several times.  They were pretty reasonable, and shipping was unbelievably inexpensive and fast.  Here are some links to their site and some part numbers:
https://export.rsdelivers.com/productlist/search?query=parker%20origami%20linear%20rail&tag=&family=8367

https://uk.rs-online.com/web/c/pneumatics-hydraulics-power-transmission/power-transmission-linear-slides-guides-positioning-tables/guide-blocks-guide-carriages/?searchTerm=Parker%20Origa%20Linear%20Guide%20Carriage%20fs-25

RS Stock No.    311-1793                                           
Mfr. Part No.    RK-FD 20520

RS Stock No.   311-1951
Mfr. Part No.    FD25-0850X0A-000-000

The cheapest approach is to buy the 850mm long FD25 rail and cut it to the two smaller lengths required for the build.  You can do this with an abrasive cut-off wheel and touch up the ends with a bench sander.

The last photo shows the different sizes of rails and cassettes.  The second one down is the one I used.  The third down would work with some modifications to their mounting brackets.  The 35, 25, etc. refers to the width of the linear rail in millimeters.

This sounds more complicated than it is.  More to come.


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## Tmate (Aug 7, 2020)

The cassette bolt patterns of each size cassette are shown in the first photo below.

In each of the newly enlarged 1/4” holes, insert a 1/4-20 x 1/2” button head socket cap screws up from the bottom.

Screw a 1/4-20 T-nut partially onto each button head cap screw, leaving about 1/4” gap underneath.

Slide one of the 30 1/2” extrusions onto each of the T-nuts on the end of the table.

Once the two end extrusions are in place, proceed as follows:

Using the 1/4-20 x 1/2” button head cap screws and T-nuts, attach an 8 hole angle bracket to the inside end of each extrusion as shown. Below. The edge of each bracket should be about 1/8” in from the end of the extrusion.

Insert 1/4-20 x 1/2” button head cap screws and T-nuts in each of the 4 remaining 8 hole angle brackets.  It is necessary to insert all 8 screws and T-nuts in each bracket to put it all together.  Set up each end of the 30 1/2" extrusions as shown, so the 36" extrusions can be slid into place.

The last picture shows the table with all 4 extrusions installed.

More to come!


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## Tmate (Aug 7, 2020)

You may be wondering why I chose to spend the money for Origa linear rails and roller cassettes when I could have just used cam followers riding on steel tubing or the like.  Years ago I made a somewhat larger version of this machine and mounted a 60 watt laser on it to see what kind of detail it was capable of mechanically.  Sixty watts isn't powerful enough to cut metal, but here is what it did in paper and leather.


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## Tmate (Aug 7, 2020)

Note that the machine with the laser mounted only used the Origa rails on the Y axis.  The X axis used cam followers riding on hardened and ground steel flat bar.  Because of the weight of the laser and cooler, I used Origa FD35 components.

In the current table, Origa rails are used on both the X and Y axes.  The non-driven end of the Y axis rides on, but is not guided by a length of 2" x 1/4" cold roll steel bar.

On the subject of being driven on only one side of the X axis -- with a machine this size, there is no reason to have the cost and complexity of a second X axis motor, circuit board, wiring, etc.

The 2" x 1/4" cold roll bar is attached to the 36" long (2" x 2" 2020 size) 8020 extrusion using button head cap screws approximately 5/8" long with t-nuts as shown in the photo below.  I should have mentioned before that the 8020 aluminum extrusions are all 2" x 2" 2020 size.


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## Tmate (Aug 7, 2020)

Pleas substitute the drawing below for the previous one.


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## Tmate (Aug 7, 2020)

Shown below are photos of the X (longitudinal) and Y (cross) axes. The fabrication of the four brackets than make up these assemblies comprise the bulk of the work in the project.


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## Tmate (Aug 7, 2020)

You will make two brackets using 4" lengths of 7" x 2" x 3/8" thick angle iron.  You will need to cut the 2" leg of the angle iron down from a longer leg.  Study the diagram of how the parts all go together to understand the logic of the chamfered holes, studs, etc.

Note that on the x axis bracket the two 3/8" holes shown along the center line are to accommodate your rack and pinion torch holder.  They should be drilled as a final step and located to suit your torch holder.  I located mine near the top.


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## Tmate (Aug 7, 2020)

As a break from all these details, here are some more shapes cut out with the little machine.


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## Tmate (Aug 8, 2020)

Two identical motor mount brackets will be fabricated.  If you had the use of the little CNC machine, they could be produced in less than 2 minutes.  As it is, you will have to do it with a cut-off saw, and a mill.  You could hand cut them with a plasma cutter and grind them smooth.  I made two machines, so the brackets you see here were cut with the first machine.

The first shot shows the bracket after being cut.  Incidentally, you do have to tap off a slight dross after cutting -- nothing like a hand cut piece, though.  The last shot shows the same bracket after a flanged 1 3/8" long _drill bushing _has been welded in place.  The _drill bushing _has a 3/4" OD and a 1/2" ID.  The beauty of using the flanged bushing is that when clamped against the plate, you are assured that it is perfectly perpendicular.  A couple of good tack welds are all that is necessary.  When it has cooled down, press a flanged 1/2" OD x 5/16 ID x 3/8" long oil impregnated bushing into both ends of the _drill bushing_.  The oil impregnated bushing MSC part number is 06454466 (currently $8.05 for a package of 5).  The _drill bushings _can be found on eBay. If you can't find them 1 3/8" long, as I did, 1" or 1 1/4" long can be substituted.  Motor mount brackets are 3/16" cold roll steel.  I bought a length of 3/16" x 4" cold roll bar from On-Line Metals to make the first machine.  I used the first machine to cut the brackets for the second machine from 3/16" hot roll plate.  Both the X and Y axis motor mount brackets are identical.

Incidentally, I forgot to provide the measurements for the threaded holes/studs on the short leg of the angle iron pieces.  They are included here.


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## Tmate (Aug 8, 2020)

You will need two spur gears (20 pitch, 15 tooth, 5/16" ID 20 deg. pressure angle).  I used gears with set screws, although you can knurl the shafts and press them on if you prefer.  You will also need two 24" lengths of corresponding gear rack.  All of this can be purchased on eBay from the seller CAROLBRENT.  They currently have auction no. 332347670951 up which contains 3 racks and one spur gear.  They also sell spur gears individually, and other combinations of racks and gears.

You will need two 4" long pieces of 5/16" diameter drill rod.  5/16" dowel pins would work if you could find them 4" long.  The spur gears must be mounted on the end of the drill rods as shown.  I reduced the length of my gear racks to 21" each, as this was my desired X & Y axis travel.  The X axis could be slightly longer, but any longer on the Y axis and you risk cutting your table frame.

You will not use the existing holes in the gear rack.  Instead, drill three 1/4" diameter holes 1/2" in from the non-toothed side of the rack.  Place them about 1 1/2" from each end, and one in the center.

The idea here is for the spur gear to disengage from the end of the gear rack before reaching the end of travel.  This eliminates the need for limit switches, and is more foolproof than limit switches.


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## Boswell (Aug 8, 2020)

Tmate, thanks for sharing the very detailed build information.


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## Tmate (Aug 8, 2020)

You will need two large timing pulleys (48 XL 5/16" ID), two small timing pulleys (14XL 1/4" ID), and two timing belts (120XL).  These are all readily available from MSC, McMaster-Carr, and other industrial supply houses.  Non name brand equivalents can be found on eBay.

This will all fit together as shown in a couple of previous pictures, and here again.  Note that the X axis gear rack is fitted upside down and attached to the upper channel in the 8020 extrusion.  This reduces the amount of plasma dust that can settle into the gear rack teeth.


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## Tmate (Aug 8, 2020)

The Origa/Parker linear rails consist of four hardened stainless steel rails embedded in an aluminum bar as shown in the photo below.  The mounting holes for the FD25 rails accept 1/4" socket head cap screws, and are pocketed so the screw heads are beneath the surface of the bar.

The gantry is simply a 32" long 2" x2" 8020 extrusion, the same as the others.  One end will have four 1/4-20 holes tapped into its end to accommodate the end support bracket, which is pictured below.  I cut both of my linear rails to 26" which, allowing for the width of the cassette,  gives me 21" of travel on both axes.  As I mentioned before, this could be increased slightly on the X axis, but the Rockler table width of 24" limits the length of Y axis travel that is possible.

The cam follower has the following MSC part number:   92610583.  They can be found for a fraction of the MSC price on eBay.

Well, I believe this provides most of the information needed to build a little machine like mine.  I hope it proves helpful if you decide to undertake the project.  Other than fabricating the five brackets, the rest of the work could probably be completed in a couple of hours -- mainly just cutting some things to length, drilling a few holes and bolting things together.  We dealt with the physical table here, and the electronics and software are something you will have to research independently.

If anyone has further questions regarding the table, please don't hesitate to post them here, and I will try to answer them.


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## Tmate (Aug 8, 2020)

I posted these photos in another thread, but I cut out these guide brackets for my hydraulic press a couple of weeks ago.


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## Papa Charlie (Aug 9, 2020)

This is a lot of great information. Thank you very much for sharing it. I have been trying to put all your posts into a chronicle file for future reference. 

Just doing some quick numbers. It appears as though by the time you were finished the cost, without the torch, runs somewhere around $3500 to $4000. Does that seem about right? Maybe a little more as I don't have the experience with CNC that you obviously do.


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## Tmate (Aug 9, 2020)

It's not CNC. but I previously built this pantograph plasma cutting machine using the same type of 8020 aluminum extrusions.  Controls are a model railroad transformer and a Grainger (Dayton) 50:1 gearmotor.  Magnetic tracer was made using iron boron rare earth magnets, a 3/4" diameter cold roll steel reflector plate, and a rotary file.  This particular torch holder was made to fit a Hypertherm Powermax 30 hand torch.  I installed a remote switch into the torch trigger circuit.

I can also share plans for this, if anyone has an interest.  It's cheaper to build than the one above!


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## Tmate (Aug 9, 2020)

The above CNC table itself, worst case, should be less than $1,000.  The electronics and software are the main expenses.

The electronics can be purchased turn-key, or assembled from parts.  Either way, check out the following links:






						NEMA 23 CNC Electronics | Avid CNC
					

NEMA 23 CNC electronics featuring Nema 23 Stepper Motors, Geckodrive Stepper Drives, and integrated connectors and motor cables for secure, pluggable connections. Our Nema 23 system provide a very reliable, affordable, and easy to use solution.



					www.cncrouterparts.com
				





			Amazon.com : CNC Controller
		


Also Google "cheap CNC control software."

CorelDraw, almost any version, will produce dxf files that can be imported by the software that drives the machine.  CorelDraw early versions are available on ebay for next to nothing.  I was not under any particular budget constraints, so I never really shopped for dirt cheap driver software.

If you can afford a full electronics/software package, such as those sold by FlashcutCNC, your total cost for the machine will probably be $3,500 or more.  Of course you can always move everything to a bigger table later if you so desire.

If you are willing to research what it takes to pull together a system from sites such as those at the above links, you could probably end up with a total of $2,000 or so invested.  If you do fabrication for a living, you would be far better off using the finished machine to make money rather than spending many hours or days trying to do it on the cheap.


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## Tmate (Aug 9, 2020)

From one extreme to the other!  Here is a 10' x 40' machine we came up with a number of years ago.  Same design, only bigger.


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## Tmate (Aug 9, 2020)

Another.  Note that when the machine was this size, we used two X axis motors.


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## Tmate (Aug 10, 2020)

This was my first effort at a CNC plasma machine.  It was a cantilever deal, with the material support table (not in the photo) off to the side.  I used two weights out of an old grandfather clock to eliminate the backlash.  Removed them for the photo.  The computer was running DOS.  That's a Hypertherm Powermax 800 plasma cutter with a machine torch.


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## Tmate (Aug 12, 2020)

Here's a 50% size Harley Davidson Fat Boy we cut out on a 4' x 8' machine.


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## DavidR8 (Jan 13, 2021)

Tmate said:


> I also have a list of all the components, where I got them, and in most cases the part numbers.  II'll try to dig that stuff up if anyone is interested.





Tmate said:


> I would be happy to share the specifics if there is interest.


I'd be very grateful for the list of components and any more specifics not detailed in this thread.


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## Tmate (Jan 13, 2021)

Turns out that it was the pantograph machine for which I had a parts list, not the CNC machine.  Many of the parts for the CNC machine are described in this thread, although not the small stuff like nuts & bolts, etc.  I started to create a set of plans, and got 19 pages into them.  I have that PDF file, but it's 11 MB and probably too large to post here.  If anyone can suggest how I might make the file available, let me know.


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## DavidR8 (Jan 13, 2021)

Tmate said:


> Turns out that it was the pantograph machine for which I had a parts list, not the CNC machine.  Many of the parts for the CNC machine are described in this thread, although not the small stuff like nuts & bolts, etc.  I started to create a set of plans, and got 19 pages into them.  I have that PDF file, but it's 11 MB and probably too large to post here.  If anyone can suggest how I might make the file available, let me know.


Thanks PM sent.


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## Gaffer (Jan 13, 2021)

Tmate said:


> Turns out that it was the pantograph machine for which I had a parts list, not the CNC machine.  Many of the parts for the CNC machine are described in this thread, although not the small stuff like nuts & bolts, etc.  I started to create a set of plans, and got 19 pages into them.  I have that PDF file, but it's 11 MB and probably too large to post here.  If anyone can suggest how I might make the file available, let me know.


I didn't see any file size limitations under Downloads. I uploaded a Colchester manual a while back that was 6MB. Give it a shot and see what happens - unless you've already tried.


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## Tmate (Jan 13, 2021)

Uploaded the file to "Downloads."  Search Downloads Only for "CNC".


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## brino (Jan 14, 2021)

Thanks for sharing this Bill!
It is both very generous and much appreciated.

Here's a direct link:
https://www.hobby-machinist.com/resources/cnc-plasma-cutting-table-partial-plans.3369/

-brino


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## DavidR8 (Jan 14, 2021)

brino said:


> Thanks for sharing this Bill!
> It is both very generous and much appreciated.
> 
> Here's a direct link:
> ...


Do you think you'll build one? 
I'm slowly putting together a parts list but curious about CDN suppliers.


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## brino (Jan 14, 2021)

DavidR8 said:


> Do you think you'll build one?



For me it's a long, long way down the road, but I like to research ideas long before I get to a project.

-brino


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## DavidR8 (Jan 15, 2021)

@Tmate I've poured over the posts and the pdf; can you confirm that the 8020 used for the entire build is 2"x2"?


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## Tmate (Jan 15, 2021)

The 8020 extrusions are Part #2020 which has a 2" x 2" cross section.

For years, 8020 would not sell directly to the consumer, but rather through a network of fluid/hydraulics distributors.  When Torchmate was using their extrusions, we had to go through a distributor in North Carolina, even when we were buying more of their stuff than most of their distributors.  A number of years later, they started selling on eBay.  Now, they appear to be selling direct via their web site.  There are still a number of other sources on eBay selling either 8020 or look alike products.


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## DavidR8 (Jan 15, 2021)

Thanks @Tmate, I happen to have a distributor fairly close to me so shipping should be reasonable.


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## DavidR8 (Jan 22, 2021)

@Tmate I'm gradually finding all the bits and pieces for the build.
The one thing I haven't been able to sort out is the shaft assembly in this photo.
Do you have a source?


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## Tmate (Jan 22, 2021)

This is a piece of 5/16" drill rod 4" long with a 15 tooth 20 pitch set screw type spur gear mounted on its end.  McMaster-Carr, MSC, Grainger, etc., all carry it probably in 3' lengths.


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## slodat (Jan 25, 2021)

This is exactly what I need. Thank you so much for sharing such detail!


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## OCD Solutions (Feb 22, 2021)

I am very tight for space as well and was thinking of doing a 2x4 table with guides or supports so I can still feed a 4x8 sheet into it without prior trimming.
I just wasn't sure if it was worth the investment for such a small capability. Good to know that height control may not be as necessary as everyone says it is. 

I also like that you used a basin rather than a water table. I like the idea of folding or collapsing legs and the ability to stand it on end for storage so a water table makes that much more difficult.


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## Tmate (Feb 22, 2021)

The reason for a water table is to reduce smoke and plasma dust.  If you use your machine outside, as I do, there is no need.  I used a basin just to catch the slag and falling debris.


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## OCD Solutions (Feb 23, 2021)

I'm not sure how my neighbors would react to me doing plasma cutting in my driveway so I have to plan on it being in my garage.
There's a good chance it's just not feasible at this location and the dream of CNC plasma will need to wait until I get a proper shop again.


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## Tmate (Feb 23, 2021)

OCD Solutions said:


> I'm not sure how my neighbors would react to me doing plasma cutting in my driveway so I have to plan on it being in my garage.
> There's a good chance it's just not feasible at this location and the dream of CNC plasma will need to wait until I get a proper shop again.



I used to do my cutting in my garage in another house.  I put the table just inside the garage door with a big fan blowing as much as possible out the door.  My garage sat to the rear of my house, but was still clearly visible from the street.  Neighbors saw some flashes of light, but no one ever complained.


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## Papa Charlie (Feb 24, 2021)

Thank you very much for sharing all of this with us. I have compiled most everything you put in here into Excel, creating a BOM and a pictorial list of each of your posts. Not sure if or when I will get started on this. Still going back and forth between buy and build. My plan is to use it for commercial purposes. I have several busy concepts I am looking at. 

I have a couple of questions:

1) If you were to build a unit that can handle a 4'x8' sheet, would you use 3"x3" 80/20 instead of the 2"x2"?

2) Why did you use the stud roller on the side opposite the stepper motor instead of the linear guide? Seems that you would have a more stable platform as the tool gets to farthest point from the stepper. But I am just guessing here.

3) What kind of torque is required by the stepper motors to drive this? I assume that all NEMA 23 motors are not equal.

4) Most of the purchased tables I see use a height motor. Is this not necessary as the design assumes very little change in material gage?


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## Tmate (Feb 24, 2021)

We used to make these 4' x 8' and larger using the 8020 series 3030 (3") extrusions.  We powered the gantry from both sides on some, and used a drive shaft on others.  If we used linear rails on both sides it would have increased the cost substantially, with no particular advantage.  Both sides of the machine would have to be parallel within a few thousandths.  With the cam follower on the far side, they do not have to be precisely parallel without any effect on accuracy.  Since both sides of the gantry were powered on the larger machines, extreme gantry rigidity was not needed.

Nema 23 motors will still work.  Nema 23 steppers can be obtained up to 450 oz. in. or more, which is plenty with a reduction via timing pulleys or gearboxes.  Steppers produce the most torque at low rpms, whereas servos produce it at much higher rpms.

Torch height controls are unnecessary on a small machine such as the one I have described above.  As they get bigger, there is a greater chance for the material being cut to be warped, or to become distorted by heat.  A torch height control makes automatic adjustments to compensate for that.  While not essential, I recommend using a thc on anything bigger than a 4' x 4' machine.

Below is a photo of a 4' x 6' table I made using 2" x 2" and 2" x 4" extrusions, and a drive shaft powering both sides of the gantry from one stepper motor.  The drive shaft can be seen in the photo.  I think a 4' width would be the limit without going to the larger cross section extrusions.


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## Papa Charlie (Feb 25, 2021)

@Tmate

I am curious why you went with a belt drive and rack/pinion system instead of a precision lead screw with the stepper motors directly attached to screw lead screws.

Forgive me if you have already covered this, but was just wondering. I noticed that many use the lead screws in their build on YouTube.

Also, would you use another stepper motor on the torch height control or does this require something else that is sensing the distance to the plate constantly and making adjustments?


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## Tmate (Feb 25, 2021)

Papa Charlie said:


> @Tmate
> 
> I am curious why you went with a belt drive and rack/pinion system instead of a precision lead screw with the stepper motors directly attached to screw lead screws.
> 
> ...


It has been done both ways, although rack & pinion drives tend to be used on the larger machines.  I originally went with that approach for the following reasons:

Absence of backlash
Absorption of stepper harmonics
Easy to switch pinion gear sizes for different speed ranges
Parts availability
Ease of parts replacement

There have been several types of torch height controls on the market:

Direct contact with material with ball bearing rollers - Seldom seen these days, used to be found mostly in the manufacture of HVAC ductwork fittings.  Impractical for a variety of reasons.

Proximity sensors - Rarely used with plasma arc.  These are generally used in oxygen-fuel cutting when no electric arc is present.

Arc voltage torch height controls - as the plasma torch tip gets further from the material, the voltage of the arc increases to bridge the gap.  The height control monitors the voltage and makes torch height adjustments to keep it within the appropriate range.  Either stepper motors or servo motors can be used, although steppers are simpler and less cumbersome.

There is a long standing debate as to whether steppers or servos are better on a plasma table.  Servo advocates claim that stepper motors can lose steps.  Stepper advocates say that servos are too complex and rely on failure-prone encoders providing feedback to the motors to function properly.  My experience has been that steppers do not lose steps in normal use.  I believe steppers are best for small to medium size machines, and at some size and weight, servos become preferable.  A 4' x 8' table is definitely well within the stepper range.  Again, these are just my views.


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## Papa Charlie (Feb 26, 2021)

@Tmate
Thank you for the explanation. I am taking what I have learned here to help me design my machine. Spent several evenings looking at YouTube videos of other machine concepts and demonstrations of some factory built units. Most small and home built units I saw had lead screws, but found several that discussed whip being an issue although many use the Ball Lead Screw for the height adjustment (Z Axis) as the short travel distance doesn't present a whip issue. The ball config lead screw provides adjustment for backlash which I think would be advantagous for the minor height adjustments of the Z axis.

Saw one design where they had one gantry but two Z axis (Plasma torch and Router Spindle) and had divided the table into two segments. Although you could remove the table covering for either and use the entire 8 feet for either operation. While I like the concept, I can see issues, fire doesn't do will with wood or saw dust and routers and wood table coverings don't appreciate water. Sort of like Motorsailers, they don't sail worth a darn and they don't motor any better.

Although, the ability to be able to reconfigure the table from torch to router does sound interesting as having two machines would be a huge space issue and of course there is the cost. The router since it is operating in 3D and the forces, does require a more rigid gantry and I believe I would have to go to a NEMA 34 as they have significantly more torque than the 23.

Still learning and thinking things out. Thanks again for sharing all of this knowledge. Love this forum and the people on it.


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## Tim9 (Feb 26, 2021)

I totally missed this thread. That’s an awesome build Tmate. The size is perfect for 90% of what I would ever need for the rest of my years. Very cool. It’s on my long list. In fact, I just hit the Follow Thread button just to make sure I don’t forget this one.


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## Tmate (Feb 26, 2021)

Incidentally, virtually all torch height controls do use screws, either acme or ball screws.  The weight of the THC takes up any backlash.  Absent a THC, a rack and pinion machine torch holder is generally used.  While there are many types of rigs that will hold a manual torch supplied with low cost plasma tables, a 180 degree machine torch is vastly superior.  It's easier to ensure that it is perpendicular to the table.  It is easier to raise and lower.  It comes with "plug and play" cables, etc.


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## Papa Charlie (Feb 26, 2021)

My plan is to buy the Hypertherm 45XP plasma cutter With Machine Torch, which is the one you recommended.


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## Tim9 (Feb 26, 2021)

OCD Solutions said:


> I'm not sure how my neighbors would react to me doing plasma cutting in my driveway so I have to plan on it being in my garage.
> There's a good chance it's just not feasible at this location and the dream of CNC plasma will need to wait until I get a proper shop again.


Just a side not for all DIY types. If you ever plan on buying or renting a house.... double and triple check with the realtor and even the city to make sure that they don’t have a Homeowners Association ruling said neighborhood.
   Homeowners Associations are the new norm....especially in newer neighborhood developments. Pure BS in my opinion. I’d run, not walk away.
    My son can’t even work on his car in the house they own in San Antonio. Check those Homeowners association’s rules. Just way too restrictive these days with a bunch of Jackasses who have way too much time on their hands with nothing better to do than to be the New Hitler Youths. These people are power junkies. They just want to show that they control the show. And they think that just because they are anal idiots who don’t want the neighbors leaves blowing on their perfectly manicured lawns....then everyone else should be just the same. 
    It used to be....a man’s home was his castle. I get some rules. But heck, if someone decided to run an auto repair in my neighborhood, I can call the city and city codes would shut him down. But not being allowed to work on your own car in your driveway. Pure Bull Pooh Pooh.


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## OCD Solutions (Feb 26, 2021)

We have an HOA but I still like to tread lightly, not for the HOA's sake, but for our neighbors and just basic good relations. I don'tneed covenants to tell me not to be an A-hole.

We just started taking over the HOA from the developer so it will be interesting to see which way our current neighborhoods goes. It's been decent so far and with all the construction of a new development, a few people have been getting away with quite a bit up till now and I think that's about to change. 

Our last HOA actually had a ruling that stated what was allowed to be in our garages. I stood up in a meeting after being cited and explained that my garage door left a mark on the floor and that anything past that line was none of their concern and good luck enforcing it. I got a unanimous roar from the crowd on that point, the citation was withdrawn and it was never an issue ever again.


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## Tmate (Feb 28, 2021)

Back in my hot rodding days, I had one neighbor who turned me in to the county zoning Department and even instigated an IRS audit.  I never understood how anyone could have such animosity toward a neighbor just because he didn't conform to a particular standard.


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## Aukai (Feb 28, 2021)

Gold mine....


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## joco_nz (Mar 4, 2021)

Awesome build and great source of ideas.   I can't access the plans in the download section and I can't seem to get the login to work to become a contributing member.  Added complication is 8020 extrusions don't exist "down under" in NZ.  There is a local version call Slotpro but it comes in 30mm or 40mm or 80mm square.  Not sure if the simple 40mm version ( https://onequip.co.nz/collections/slotpro/4-Series ) will do the business.

At the moment I'm looking at making a variation of this based on materials to hand.  I have about 3m of 35mm steel square tube (3mm wall) and similar amounts of 40mm angle (again 3mm thick). A bunch of skate board bearings and associated h/w.   I think with that and looking at your original design from "back in the day" I can create a similar design concept without having to resort to the linear guides. I have dual nema34 motors and drivers, a spare mesa card and PS, plus good knowledge of linuxcnc and spare computer and touchscreen.  The only thing I think I will need to source will be timing belts (unless I try direct drive) and the rack and pinion (seems to be very cheap)

IF I have some success I can always reclaim the steel back to the stock pile after building a cleaner version with linear guides and perhaps the local SlotPro extrusions.

Thanks for sharing.  It's helped a lot generating some really good ideas.  Just need to make things work on prototyping budget.


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## joco_nz (Mar 11, 2021)

Continuing on my "on a budget" thinking I was hoping someone (Tmate perhaps) might be able to help with:

[1] On the original build Tmate did I am trying to figure out what bearing arrangement was used to connect to the flat bar. This is the side where the motor is, not the "floating" end.   I can see the bearings that will give rigidity to stop the gantry arm from wiggling under motion.  I can not see how he is keeping that section of the motion system up.  i.e. so it does not slip and slide on top of the flat bar bolted to the 8020 extrusion.  Are they flanged bearings? Are there some bearing rollers else where I can't see that are riding directly on the top of the flat bar?  Would love to know.

[2] Looking at the cost of linear motion parts where I live I am finding I can source SBR16 rail and associated bearing blocks for half the price of the equivalent square linear guide styles.   Would SBR16 with a couple of mounting blocks be a reasonable alternative to the 20 or 25mm linear guides being used/suggested?  I'm sure not ideal but for a compromise on a system that is never expected to be 0.02mm accurate does it matter?

Appreciate thoughts and advice.

Cheers - James.


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## Papa Charlie (Mar 11, 2021)

joco_nz said:


> Continuing on my "on a budget" thinking I was hoping someone (Tmate perhaps) might be able to help with:
> 
> [1] On the original build Tmate did I am trying to figure out what bearing arrangement was used to connect to the flat bar. This is the side where the motor is, not the "floating" end.   I can see the bearings that will give rigidity to stop the gantry arm from wiggling under motion.  I can not see how he is keeping that section of the motion system up.  i.e. so it does not slip and slide on top of the flat bar bolted to the 8020 extrusion.  Are they flanged bearings? Are there some bearing rollers else where I can't see that are riding directly on the top of the flat bar?  Would love to know.
> 
> ...



I am no expert, but have been doing a fair amount of research in this thread and equipment and on YouTube.

1) If I understand your question correctly, the square blocks are the bearing that ride on the rail. The only other bearings are the bushings that he used in the drill guide which he as used as a support tube for the gear shaft.

2) I have seen a lot of Plasma tables built with the linear rails you are describing. I have also found very similar blocks to the ones that Tmate has recommended on Amazon for a fraction of the cost of the recommended. My thought is that if you are not going to do production (8/5) every day, then they will probably be fine. From what I have learned, Tmate designed and built a very stout table suitable for industrial use.

I hope I have answered your questions adequately.


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## joco_nz (Mar 11, 2021)

Papa Charlie - thanks for the response.  Appreciate you taking the time.

Re #1 - my question was with reference to his FIRST build.  In that one I think he used a linear guide on the gantry cross rail only.  It was his bearing setup on the other axis I am trying to unpick.   See attached image with the yellow oval showing the specific area of interest.  It is these bearings and how this specific linear section is setup from a bearing support point of view I am trying to fathom.

Re #2 - I'm in New Zeland so anything from Amazon larger than a book becomes super expensive due to shipping and now with international shipping capapcity butched by COVID it's even worse. I can ship direct from China okay given their shipping subsidy system. But you take a crap shoot on long items like a rail being striaght on arrival.  Much easier to pay a small premium and deal with local suppliers.   Anyways, you are correct that this is not production, this is hobby/fun/interest motivated.  I will make parts for myself and for friends and others for beer money or just beer.  IF it ever gets more involved and I make one-off/small-run parts for money then I will invest in a build more akin to TMate's version with 25mm linear guides all around.

Again, apreciate the time taken to consider the questions and responed.

Cheers - James.


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## Tmate (Mar 11, 2021)

I will try to shed some additional light on the subject.  The machine in the post above only used an origa linear rail and cassette on the Y axis.  The X axis used a piece of cold roll steel bar as the rail, and McGill needle bearing cam followers.  Two 3/4" cam followers gripped either side of the rail at both ends of the short aluminum extrusion.  A single 1" diameter cam follower supported the gantry at both ends of the short extrusion and at the far end of the long extrusion.  The cam followers were mounted on 3/16" thick plasma cut brackets.

It would be difficult to use a linear rail on both sides of the X (long) axis partially because of the cost, and partly because of the tolerances in the cassettes/rails.   The mere expansion of the table from heat would likely cause binding.  With the gantry being merely supported on one end, it is free to move in and out slightly on the cold roll bar as it moves back and forth.  The little 2' x 2' table was affordable, as I bought one 48" linear rail and cut it in half.  I used an abrasive cut-off saw to do it.

With regard to the cheaper rails and cassettes available on eBay and elsewhere.  I have experimented with a variety of these.  They typically use ball bearings riding directly on the rail, and fall out without a great deal of provocation.  They also get jammed up from the plasma dust rather quickly.  The Origa/Parker/Hoerbiger cassettes use captured roller bearings held firmly in place in an aluminum housing with felt wipers at both ends.  We have machines out there that have been in daily use for years without a cassette failure.

Please feel free to ask any further questions you might have.  I will be happy to help if I can.


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## joco_nz (Mar 11, 2021)

Tmate - thank you very much for responding. That pic is perfect and along with your text tells me eaxctly what you had in play.  AND I have the parts and tooling in the garage to do make exactly what you have shown either as a 4mm folded structure of 6mm welded fabrication.

Re the cheaper rails etc, yes I have been a bit leery about the grit issues.  I think I will pursue a style like your first iteration for X axis and probably a less elegant bearing/v-bearling like setup for the Y (again using what I have quickly to hand).  But it should be all pretty mess tolerant while cuttng and a quick rag clean down between sessions will keep the worst of any dust/muck under control.

For the record your version 2 build is super clean and is on the "really want to do it that way down the line" list. 

A question I thought of:  the "T" where these bearing cam follower assemblies are mounted, how much length did you allow for that so as to give enough separation between the follower assemblies to keep the Y axis reasonably ridgid to in relation to X?  I've been modeling on circa 250mm.  That's about 10".

Cheers - James.


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## Tmate (Mar 11, 2021)

joco_nz said:


> A question I thought of: the "T" where these bearing cam follower assemblies are mounted, how much length did you allow for that so as to give enough separation between the follower assemblies to keep the Y axis reasonably ridgid to in relation to X? I've been modeling on circa 250mm. That's about 10".



The longer the better.  Note that while the aluminum extrusion is relatively short on the little machine above, the brackets position the cam followers out another couple of inches on each end.  The longer your x axis, the greater the separation needed.  If both sides are driven, the problem diminishes.  On larger machines I have mounted gear racks on the inside of both frame sides and used a double shafted X axis motor and a drive shaft to power the opposite side.  The drive shaft was made of 3/4" cold roll round bar, with a spur gear on the end.  I had to blow off the gear racks more often, but it worked perfectly.  If you have an interest in that approach, I'll dig up a picture or two.


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## joco_nz (Mar 11, 2021)

Tmate - I think I'm looking to build the same general sized cut area you are using.  You thread title of "CNC Plasma Cutting when you have no space" perfectly describes my situation.  I have a garage full of great gear (Good sized, mill and lathe, Surface Grinder, small shaper, small cnc mill, work/wleding table with 1" steel top, welders and blowback start plasma cutter, surface plate and 3 mobile tool chests.  So STUFF FOR AFRICA - lol.

Sorry - back on topic, 24" (i.e. 600-610) cut area will be just fine. I am therefore roughly planning on X axis rails of about 1000mm (39.4") and a Y axis rail of about 750-800mm (29.5" to 31.5"). So if you know what your wheel spacing was (roughly) that would be rather useful.  10", 12" or something else?


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## Tmate (Mar 12, 2021)

joco_nz said:


> Sorry - back on topic, 24" (i.e. 600-610) cut area will be just fine. I am therefore roughly planning on X axis rails of about 1000mm (39.4") and a Y axis rail of about 750-800mm (29.5" to 31.5"). So if you know what your wheel spacing was (roughly) that would be rather useful. 10", 12" or something else?



Hopefully these photos will be of help.  Note that the pictured machine used 3" x 3" extrusions and a 35mm linear rail.  While both of these were overkill, the assembly was a bit stiffer than my later 2x2.  Also, the motor and X axis gear rack were mounted on the inside of the short extrusion, slightly reducing the need for a wider bearing spacing.


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## joco_nz (Mar 12, 2021)

Super helpful.  Saturday morning and I’ll be spending it at the whiteboard and ferreting through the steel pile working out what I have and what is best to use.


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## Tmate (Mar 12, 2021)

joco_nz said:


> Super helpful. Saturday morning and I’ll be spending it at the whiteboard and ferreting through the steel pile working out what I have and what is best to use.



We have friends who live in Christchurch.  Spent several days in NZ a couple of years ago.  Very beautiful country.


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## joco_nz (Mar 13, 2021)

My extended family is all from that area.  I original came from a town south of ChCh and spent a lot of time in the city growing up and on family farms in the area. Will always be a Cantabarian.


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