[AndiKid]

Hey to everybody in this great forum. After being interested, studying and then planning a CNC Plasma Table for a long time now I finally decided to go ahead and get my project off the ground.

My name is Andreas and I am 29 years old and live in Berlin / Germany.

After getting so inspired by Dave's machine I decided, that this is exactly the way I want to go and then started by laying out and planning my table in Rhino 3D.

I want to quickly take the chance to explictly thank Dave so much for his incredibly nice built table as an inspiration, and even more, I want to thank him for his outstanding kindness and support! Vielen vielen Dank!!

First step of the build, was to come up with the dimensions. I decided to go with the measurent of 3x2 meters since this is the maximum width of my door in the shop so this size will come in handy if I ever want to take it out of my shop.

It is also perfect for standard medium sized sheets which in Germany are 2,50m x 1,25m and it will also hold a large sized sheet which is 3m x 1,50m.

I then cut and built the Frame out of 100x100x4mm cold rolled steel tube and the cross beams out of 60x60x3mm. The cross beams will be my under construction to hold the waterbed.

I also wanted to absolutely make sure the table will be mobile so I put heavy duty wheels as well as heavy duty mounting feet.

So here is a picture of my ready welded frame:

[GaryCorlew]

Very nice work!!

[AndiKid]

Thank you Gary, I tried to keep the warping to a minimum but it was very difficult.

I will try to compensate the small warps in a later stage of the build. The precision is very very important to me since I want to use my machine as a router as well.

After finishing the table welding I tried set up and allign the linear rails. They are from Hiwin and they are expensive.. But they are mega precise and will give the machine a good base.

Because my shop has a very uneven floor and I dont have a floorplate or anything i can use as a reference, I used cold rolled angle irons, attached them across the table and used them as a reference.

I then used one of my linear rails as a spacer and then made a center punch that precisely fit the holes of the Hiwins.

I would be very happy about people giving me their opinion on this since I don't feel it's perfect at all, but as Dave said the THC will compensate for minor irregularities but it worries me very much about the routing function.

[Boogiemanz1]

Andy, what size are your linear rails? I am going to build a plasma machine, but want it heavy enough to change it to a router later, if I decide to build a different plasma table. I am planning on using the hiwin also but am having a hard time deciding on which ones..................jb

[MBG]

Very nice, I will be following this build.

[AndiKid]

Thank you very much MBG. I really appreciate your friendly message.

I will keep on posting and really hope for the support and input of the people in the forum for the upcoming problems and challenges.

@Boogiemanz1

These are the linear rails that I chose for my machine:

6 x HGW30 HC ZA H
2 x HGR30R 3000 H
1 x HGR30R 2000 H

They are for sure very big and maybe a little overdosed but I prefer the safety and strength too make sure I don't encounter problems on such a vital part of the machine.

I also ordered for the rails, instead of the standard plastic caps, copper caps to avoid dust and dirt in the rails.

One important thing I did wrong in my choice is that the "sleds" (i don't know how you call them in english) are the version with the red plastic ends and the HGW sleds are also available in version with metal ends.

[Boogiemanz1]

Thanks ANDI, I have down to order the Heavy duty 30mm slides, I'm sure that the 25 mm would be all I never need, but overbuilding things seems to be a sickness with me. Hopefully I can keep my gantry light enough that I can achieve the speeds necessary for light material. Thanks again for your reply, and I'll be watching your progress...jb

[AndiKid]

So, I made some more progress in the build and finished drilling the holes and counterbores to attach the Hiwins.

The wall of my steel tube is only 4mm and that seems not enough for me to create a strong taper connection. So I decided to use blind rivet nuts to create a really solid reception of the bolts. You find some pics attached.

I also designed the aluminum waterbed in Rhino and then ordered huge sheet of 3mm aluminum (4m x 2m) and had the four edges bent by a company since my bench in the shop only bends 1,5m sheets.

The bending was € 89,- which translates to approx. $ 120,- so I think this is a very good investment to avoid problems and save time. I then only had to weld the four small corners and waterbed was done.

Next I will attach the rails, design and create the slatholders and try to place the rack.

[AndiKid]

and here's the rest..

[Boogiemanz1]

Very nice work Andeas. I have been torn between adjusters on the bottom or wheels. I have 12foot doors on both of my buildings and a fork lift, I think I will go with adjusters. My wall thickness is 0.186", not much more than yours, so I will keep your blind nuts in mind also. Thank you for posting the photos. I am still gathering parts , and will begin building my machine in the next thirty days................jb

[AndiKid]

I have used both adjusters and wheels. Meaning, when the table sits on the adjusters the wheels are up in the air. Then I level the tabel by adjusting each individual mounting foot.

When I then put the table back on the wheels I just lift the table a few inches up with a jack and then turn the adjusters so far up so the table will be back on the wheels.

The pic hopefully explains it better..

[dnelso]

Andreas
Looks very nice.
Dave

[Boogiemanz1]

Good tip Andreas..............jb

[AndiKid]

For a couple of weeks now, I took on transfering the whole project to Autodesk Inventor and tried to teach me this nice program.

I really would like to build my gantry as rugged as possible and would like to strive for the design that you find in the pictures attached.

As the Hybrid concept is really difficult to unite in one machine (ultra light gantry for plasma - Heavy for routing) I would like to ask for some help.

I bought the 620 oz. Dragoncut of CandCNC. Ratio as of now 3.6:1

The combined weight of the Gantry would be approx.:

Steel Tube: 48 Pounds

Hiwin Rails: 40 Pounds

Hiwin Sleds: 6 Pounds

4 Gantry Sides + Top Plate for Motors: 35 Pounds

Motors: ?? Maybe 6 Pounds

K2 Z-Axis: 13 Pounds

Rack: 17 Pounds

Other Stuff like Screws, Pinions etc.: 10 Pounds


Total: 175 Pounds



It is very heavy I know.. Would it still be possible to build my machine like this? Will I get the speeds/acceleration that I need for Plasma cutting or should I maybe get stronger motors?

[Arthurmetal]

Hi AndyKid,

Nice build, I like the sturdy frame.
In my opinion a plasma table and a router have a few conflicting demands in their specifications and difficult to combine in one (home build) machine.
For your plasmacutting you may want the gantry as light as possible for speeds of at least 3000 to 5000 mm/sec and as much acceleration as possible. Accuracy is usually good enough when your backlash is mimimal.
So speed, acceleration, vibration, and inaccurancies as a result of backlash may be your major concern. This is quite different from a router.
Your concern may be to choose your motors so they can accelerate the weight of your gantry fast enough.

So far I am talking from experience. I build my plasma table a year ago. Overall out of square tube 40x40x2 mm. It serves me well but it is build too light weight: torchholder and gantry rolling with ordinairy bearings (22x7x8mm) on the 40x40x2 mm tubing for the x- and y axis. 2x Nema 23 and 1x34 (for the x-axis) steppermotors driving a toothbelt.
Vibration and lack of rigidity at high speeds is my problem now.
I am planning to rebuild this with linear rail some day.

Another issue, I intent to start a separate topic on this, is the tremendous polution of the whole table and everything around it. The watertable may catch an 80 percent of the dust. Another 15 percent is, mixed with splashed water, deposited as a sticky black mud over your table. Keep in mind that the torch is continuously blowing straight into the watersurface. Especially when the torch passes over already cut holes a spray of water hits your z-axis assembly.
So keep your lineair rails covered and away from direct spray and dust.
You also may want to close the gaps between the watertable and the frame.
In addition to my watertable I have a large cagefan (10 inch exhaust) running over my table to vent the fumes which come from between the sheetmetal and the watersurface (usually less than half an inch).
A recent addition to my table were two lengths of angle iron (from sheetmetal) in a 45 degree position, facing inwards towards the table, mounted on the edge of the watertray. This to reflect the sparks and waterspray back into the table. (there is also a lot of dust ON TOP of the sheetmetal as well, especially during piercing).

Obviously a lot more to comment on, but succes for now, Arthur

[AndiKid]

Hi Arthur, Dank u voor uw boodschap

Is there a math formula that can be used to know the maximum weight of the gantry for it to achieve the speeds needed?

The motors that I have right now are the 620oz.

I know that Force = Mass x Acceleration

Could somebody help what accelerations I will need? Or is this not what I need to find out? The speeds for plasma you defined at approx. 200 Inches / minute, correct?

This is really really difficult for me but I would like to find this sweet spot point where the machine can do both, plasma cutting and routing and I really need help.

[AndiKid]

After reading quite a bit more I know that the Diameters of the rack & pinion etc. plays a factor as well.

What I would love for this is to be some kind of formula so people can sort what they need, to achieve certain speeds, accelerations and the possible gantry weights.

I can tell that Torchhead just has incredible knowledge in this so maybe he or somebody else will be able to help.

I intend use the following setup:

Rack: Modul 2

Sprocket: Modul 2 - 20 Teeth - Diameter: 44mm (1.73 Inches)

Pinion 1: HTD 15mm - 18 Teeth - Diameter: 28,65mm (1.13 Inches)

Pinion 2: HTD 15mm - 72 Teeth - Diameter: 114,59mm (4,51 Inches)


As stated before I want the machine to be able to function as a router and as a plasma cutter for thin materials as well. I hope you guys will be able to advise.

[Boogiemanz1]

Andreas, glad to see you are working on your machine. On the CandCNC website it says that you need to keep your gantry at 90 lbs or less for the system you have. I believe Tom has stated that the gear reduction should be around 3:1 for plasma. Can you build your gantry out of aluminum?.........jb

[AndiKid]

JB, I of course, could build the gantry out of aluminum and instead of using 2 Hiwin Linear Rails, I could use only one rail etc. etc.

BUT!

the goal I have, is to find this perfect point and setup for a hybrid machine.

I know, I make it difficult for me but I hope also for other people who want to also build a similar machine will benefit from this thread and the theoretical and practical input from everybody.

I found out from the 2 great people Torchhead and Jim Colt in other threads that min. acceleration must be: 15.5 inch /s^2

My gantry weight is: 175 Pounds

F=m*a
F= 15.5 Inch/s^2 * 175 Pounds
F= 2.712,5 (Ounzes???)

Is this correct?

What does this mean for the motors?

620oz is the theoretical value of Force.

I use two motors for the X-Axis. Let's say the motors have 380 oz "real power" so they have 760 Oz together.

With a 3.6:1 Reduction it would mean 2.736 Oz.???

[Arthurmetal]

here is some basic info on how to calculate on steppermotors (in german):
schrittmotor einfache schrittmotor regeln :idea: