Looking to build a new 2x4, need some suggestions.

[BrooklynBravest]

Hey guys, been lurking a while finally posting.

I have a langmuir systems table with a hyp 45xp that I expanded into a welded 2x4 and has more than paid itself off.

I can't live without a THC anymore but I have a very small home fab shop in a 20x10 space so going larger is out of the question. The 2x4 handles everything I could need so I basically want what I have with a THC and potential to use a router as well.

That said, I want to build a table like Wrights or Premiere plasma. To avoid issues I was going to purchase the electronics enclosure ready to go from premiere plasma and build the rest myself. They said they would sell me the enclosure for about $1500. The remaining parts I should be able to make myself with the langmuir setup or purchase them on ebay.

My design I have in the works is below. I will modify it once I see how the gantry brackets actually need to fit.

Mostly just looking for any and all suggestions on going forward as I am definitely still an amateur in this. I have full welding/fabricating capabilities here as well so no custom part is really an issue.

Also curious if anyone has the file for the gantry bearing/motor assemblies that everyone seems to use on the 2x3? I know I can get it on ebay but im guessing its a publicly available file?

CNC Plasma Table v2.png

[robertspark]

2x2 is more than sufficient, no need IMHO for 2x3

https://grabcad.com/library/linear-bearing-carriage-1

[robertspark]

https://grabcad.com/library/cnc-plasma-12

[BrooklynBravest]

Thanks for the reply. Very helpful.

I’m inclined to go with the 2x3 just so it’s beefier i see the commercially available versions all use 2x3?

I can easily make that bracket an inch taller though.

[acourtjester]

I developed an axis slider that would work very well for what you are trying to do. I will give you the DFX files so you can cut the parts yourself.
Simple change of dimension to give you the 2" X 3" you are looking for.

new type X slider.JPG

new type X slider (4) A.jpg

new type X slider (3)A.jpg

[robertspark]

acourtjester, nice design, well supported bearings + bearing adjustment by CAM / offset. Nice.

Plasma is all about acceleration, so lightweight is better than percieved rigidity.



If you look at the above image, the side rails can be whatever profile you want, but bear in mind that you have shown the 3" in the vertical orientation..... why, what load are you trying to support ...... all you have is the vertical load of the gantry.....

The gantry should be lightweight so it ACCELERATE fast so that the machine can change direction rapidly (0.3G gets mentioned a bit)

so the force that the side rails get subjected to is actually the change in direction..... not a vertical force..... that is constant.... there should be no bow in the side rails given they will probably be bolted / spot welded to the frame.

I am not trying to rubbish a design, just maybe give you a bit more to think about that is all.... think about the direction the rails will be subjected to force in motion (G forces of acceleration + jolt and jerk [instantaneous motion of trapezoidal acceleration])



4' wide is not very large / wide.... OK it will need to be ~5' wide to get 4' of movement because the z axis carriage will take up space .... but a 2x2 rail will be subjected to very little downward force (only the weight of your z-axis carriage and the UDL (uniformly distributed load [weight]) of the ~5' gantry rail .... the force is again the forces of motion and change of direction as the downward force is constant

I have been meaning to change my gantry rail (2x2x1/8") from mild steel to aluminium (1/3rd of the weight) which will again improve acceleration.....

Just because a commercial table does it does not mean its right..... they may have done it for another purpose.... such as a wide or longer gantry machine, or one that can take a router or a drill or engraver etc.

[Rodw]

Robert is on the right track using aluminium. I used 40mm x 80mm x 4mm ally with folded ally gantry ends. Its amazing how the weight stacks up.

This is a very nice build in progress of a small table by Clive in the UK that might interest you.
https://photos.google.com/share/AF1QipP ... FjcmpRbHpB

He has a build thread here
https://forum.linuxcnc.org/plasma-laser ... on?start=0

Like me, he's using the Linuxcnc Plasmac config with kickass THC controlled internally by the motion controller. I'm in the process of building a reference controller using Mesa hardware that might even be available prebuilt.



A few more bits turned up today. You are looking at a Mesa 7i96 ethernet board and a Mesa THCAD to read the torch voltage on the right. Power supplies from left are 5 volt for logic, 24 volt field power and 24 volt isolated power supply for ohmic sensing. I have not added up everything on that rail but there is USD $188 in the Mesa cards. I wanted to mount it all into an easy to fabricate, plasma cutable case.

So don't rush into buying your controller yet!

[BrooklynBravest]

Thanks guys for the tips.

I will definitely drop down to 2x2 tubing it makes more sense for sure and its much cheaper.

Jester you're really everywhere aren't you lol. Thanks fro the design as well.

I am trying to get a quote for the enclosure ready to go from premiere plasma but I have no idea how this guys is even in business. It is very daunting to me to build the electronics myself I really have no idea what im doing at all. I've built computers but this seems more involved than snapping PC parts together.

[TJS]

Welcome. I am here too. Your build should be good. I also suggest looking at CommandCNC package. Has a bit of a learning curve but works good so far.
T.J.

[acourtjester]

Well we all have our opinions and reasons for why we do things, I am not an expert but have built 8 tables and have cut many shapes in both artsy and mechanical forms in different thickness. Speed is important but your not trying to get airborne. I may get beat up over that statement but, I have help many build tables, and it works very well for me. I will help but if not I'm happy where I'm at.
If you have built computers, you should not be afraid of the electronics. Tom C. at CandCNC sell a complete electronics kit for DIY types and other sell the components, you interconnect modules. No virgins throwing in volcanos involved, not all who have built a table is involved with rocket science.

DSCN2381.JPG

[BrooklynBravest]

I just took a look at CandCNC

To be clear this doesn’t use mach3 right?

$2100 for the complete electronics setup isn’t too bad, it would get me all I needed under $3500 i think total.

[robertspark]

.... Speed is important but your not trying to get airborne.

... No virgins throwing in volcanos involved, not all who have built a table is involved with rocket science.
...

Good valid points

My point was 2x3 is probably overdesign.... given most of the force is due to motion the downward force is static..

This is probably the wrong design idea in my opinion:


But each to their own.....

Dont worry about the controllers yet (commandcnc / linuxcnc / mach3 etc).... just build the table then consider options later...

[BrooklynBravest]

Welcome. I am here too. Your build should be good. I also suggest looking at CommandCNC package. Has a bit of a learning curve but works good so far.
T.J.

The gang is all here then.



I like the idea of building the table first and then worrying about the electronics platform. I didn't consider that it doesn't really matter in the structure of the build.

Just so I know what to provide for as clearance to get a full 48" cut, is a mount like this suitable for what I want to do?

https://www.ebay.com/itm/Z-AXIS-CNC-PLA ... SwAClcbxD0

[BrooklynBravest]

Premiere Plasma quoted me $1400 for the electronics enclosure, 4 steppers and cables.

I’m not sure what components that includes but it seems like a pretty good deal? Should i go that route or try and do better on my own?

[tcaudle]

I just took a look at CandCNC

To be clear this doesn’t use mach3 right?

$2100 for the complete electronics setup isn’t too bad, it would get me all I needed under $3500 i think total.

Look at the Most Popular Bundle https://www.candcnc.net/store-home/most-popular-bundle/ in the Discounts bundles section. Hardware, high torque 620 oz-inMotors , cables, DTHC 5 Hyper Fast THC, CommandCNC LINUX based control software, free drawing program , free CAD, Full license for SheetCAM advanced posts for Plasma and Routing . Compatable with Vetric VCarve Pro or Aspire for 3D routing. LINUX PC will connect via WIFI to wireless router and Windows PC's on the same network. Ethernet control and Real time motion and feedback. 2585.00 full bundle. New Shuttle MINI PC is an upgrade and you can choose our Super Z with built in Ohmic Sense, mechanical Z home swtich backs up ohmic for touch off and there is an optional breakaway torch holder with estop sensors.

Just released Ubuntu 18.04 version and CommandCNC rev 1.2

[tcaudle]

If you are going to use a direct drive linear mechanical type then I recommend the larger 620's unless your total gantyr weigh is below 50 lbs and you don't want to do any routing.

[BrooklynBravest]

Thanks for the electronics link.

Right now this is where i stand on the design. Reduced everything to 2” tube.

Does anyone know off hand what a good allowance for the offset of the torch to one side with a z lifter is to ensure I have the full cut area I want? I’m guessing around 3”?

I will probably change out the carriage style for a flat top one that will allow me more room to support the rail from underneath and keep the table narrower to fit my space.

[djreiswig]

Make sure you leave enough travel room on the sides in case you want to add a scriber of another tool beside your torch. Mine doesn't have enough, so my scriber won't reach to one side of a sheet.

[BrooklynBravest]

How much extra travel would you suggest?

My area I can fit this thing is 34” x 64”.

[TJS]

I know you are in NYC. However my offer stands to take a short trip to CT. I am 50 minute ride away from you depending on traffic. You can see how my table works with the Commmand CNC set up. Any weekend, Sat or Sun. Just let me know.
T.J.

[robertspark]

may be worth considering as an idea for your Z.... + if you want a scribe. Plasma swarf is very hard and fine dust and it gets everywhere, worth considering if you plan on using round rail + bearings and also delrin nuts with a leadscrew (all depends how much cutting you intend doing).

https://www.cnczone.com/forums/plasma-e ... cnc-2.html

https://www.cnczone.com/forums/plasma-e ... ost1128175

https://www.cnczone.com/forums/attachme ... 1295375076

[djreiswig]

I'd leave enough so that a tool on the left side of your z can reach the right side of a sheet and a tool on the right side of your z can reach the left side of the same sheet. So you'd want whatever the distance between the two tools extra. Probably just add the width of your z plate to the biggest sheet, that should cover it.

[BrooklynBravest]

If I did the math right it should have a full 24 x 48 cut range with a little extra to make life easier.

[BrooklynBravest]

Updated the design again. I'm really happy with how it looks now.

Drop in water table. Overall footprint 36"x64" full 24x48 cutting area.

Anyone have some thoughts on it? I think I will go ahead and start building the upper angle iron frame if no one sees an issue. Do a little bit day by day and eventually drop some electronics on it.

[robertspark]

instead of box section for the legs you may want to consider equal angle iron that way the 4 legs will be the pillars bolted to the rails and you can weld the angle iron braces into the inside edge of the angle iron legs

just a suggestion