[outofoperation]

Hello Andi,

I will give it a try for my own calculation training- without any warranty. But I hope, the guys here will correct me, if my maths are completely wrong...

But rather I will use metric units...

a = 15.5 in/s² = 0.4 m/s²
m = 175 pounds = 85 kg
T = 380 oz/in = ~2.7 Nm
R= pinion dia/2 = 22 mm
reduction 3.6:1

Available force you will get from the steppers is : force F = torque T / radius R

F= (2.7Nm * 3.6) / 0.022m = ~ 442N

With two steppers you will get doubled force, ~884N. Then the weight of your gantry should be roundabout 90kg max. - friction not included!!


Acceleration a=F/m (try this online calculator )

a = 884N / 85kg = 10.4 m/s² (this is 25 times more than the min. rated acceleration??? Jim? Tom? Please comment :drowning: )

I hope this is a little useful,

Steff

[gn3dr]

If you are looking for both light weight for plasma and rigidity for router did you think about making a two part gantry. Was just thinking you could have a lightweight gantry for plasma and then when you want to use it as a router, roll up the second half of the gantry which could have a second set of bearings running on the same tracks and bolt it to the lightweight gantry to increase rigidity?

[AndiKid]

Hi gn3dr, thank you for the posting of your idea! It's an interesting possibility.

I could imagine if you choose the right design the connecting of the two gantries would be very cool.

As of now I lean more towards either getting bigger motors or use a second set of motors.

Did anybody, that owns a CandCnc Bladerunner Package, ever change the motors? Is that possible?

[fanefane]

Hello! Congratulation for you project! I'm want to make a cnc for plasma cutting, too. What Torch Height Controller did you buy? What do you think of this plasma cutter Plasmaschneider CUT 60 Inverter von STAHLWERK, sowie Original Zubehör ? Is it good, can I use it with an CNC?

[Arthurmetal]

Fanefane,

My opinion on the Stahlwerk Cut 60: typical chinese entry level cutter. You recognise them from a mile (the casing and the price). The dutycycle is not bad. But look at the video: it takes him about 25 seconds to cut the 100x10 mm piece what makes for a cutting speed of 240 mm/minute. Not very impressive. Make shure you have sufficient stock of comsumables; they may go fast under CNC use. Your CNC dutycycle can be over 90%.
For THC you need to get a ArcOK signal out of the machine, might be difficult. Switch override and arc-voltage is usualy no problem. Again, it is what you pay for. I should not choose a machine like this if you expect to do anything more than some hobby cutting.
Regards, Arthur
(Powermax 45 user)

[fanefane]

Can you give me some details about the ArcOK signal? I'm thinking to buy Powermax 45 with a good price.

[Kerryfisher]

Hi Andy,

How did the rest of the build go? I am swaying to a build with the exact same specs, well nearly not quite as big with those rails
I to was well impressed looking at dnelso's builds, think I will be working along those lines.
What way did you go with the rack/pinion drive did you do the same as Dave and have it fixed? how hard was it to keep the rack parallel to the rails?

I quite like your idea using the the nutserts in the thinner wall, did that work out ok?

I'm about to order the same kit from Candcnc as well.

Cheers
Sean

[AndiKid]

Hi Sean,

I used a rack pinion just as Dave's Build. I used 3.6 : 1 set-up (72 Teeth to 20 Teeth) and had all the side pieces routed by a company due to precision reasons.

Keeping the rack parallel to the rails is very easy.

I had a company route small metal pieces precisely 25mm by 100mm (precise by the 100th of a mm) and used them as spacers.

That means i clamped the little metal pieces between the rail and the rack and so I knew that all over from beginning to end the distance between rail and rack is exactly 25mm..

The nutinserts worked great and I am happy that I used them

[Kerryfisher]

Thanks for the info Andy, thanks for the gear sizes as well.
That sounds very good with the rack, did you use much clearance with the rack bolts just in case?
As far as I can make out Dave said he used a bolt to put pressure onto the pinion, that's the only part I cant quite make out from all the great photos I have looked at, can I ask did you go the same route as well?
Thanks again for your time, much appreciated!

[AndiKid]

You are very welcome! I received so much nice and friendly support so very happy to provide support.

Strangely enough this is exactly the part of Dave's machine that I never understood either. I don't use it but I also would love to know.

[Kerryfisher]

I did also mean to ask if you needed to order the extra (5') length of cable with the Candcnc kit motors on your table, about to order tomorrow before the price increase.
Thanks Andreas (sorry don't know where I got Andy from)

[Kerryfisher]

You are very welcome! I received so much nice and friendly support so very happy to provide support.

Strangely enough this is exactly the part of Dave's machine that I never understood either. I don't use it but I also would love to know.

Is the gear/bearing mounting slotted to allow a tight fit on the rack?

[Squickmon]

did you ever complete the table? how does it look?

[grinder_gary]

we provide the laser CNC cutting machine, cnc router and plasma cutting machine, we have a potable machine that is just USD2000,
china famous of Pipe plasma/Fiber laser/Gantry plasma/Co2 cutting machine manufacturers and suppliers Laser Solution - CO2 laser cutting machine, fiber laser cutting machine, waterjet cutting machine, CNC Router Machine, laser engraving machine

SPAM

[assadi]

Nice table,
I want to build the same. I liked the rivnut idea, but i have difficulty buying them in israel (200pcs cost 250-300$), where can i buy them online!? Stainless steel Countersunk M5 rivnut/nutsert with grip range up to 4mm!!
Appreciate your help

Sent from my ONEPLUS A3000 using Tapatalk

[Kerryfisher]

Here is what I ended up with - https://goo.gl/photos/KX4EChnngmNtH4e18
It's been earning it's keep most days since then, it doesn't look quite as clean now!

No need for nutserts, my Y axis beams were 5mm wall, plenty to tap into with all those bolts, I did use 80x80 x 3mm for the gantry I also tapped those but with the single linear rail wasn't really happy with it so I drilled/tapped a piece of flat 5mm x 15mm x length of gantry and fed it inside the box section and bolted through into that.

Now after 5yrs nearly I had to replace the two bearing blocks as they were starting to go a bit lumpy, they were LSK rail/blocks I used so maybe not best quality.

I'm also not sure the single rail was the right way to go as I'm also seeing a little back and forth play when pressure applied, you don't really feel play but just doesn't seem as sturdy as when they were new.

I'm also ready for new rack and pinion gear on the gantry but after 5yrs It's not bad going, I only used standard mod 1 rails, would still use again though, Y axis rack and rails are perfect still.

Steel water tank didn't last that long 2.5yrs, it had some strange silver reaction happening in a few places around the inside edges that ate through in a few places so I added a plastic tank.

I guess my gantry will be around 130lbs the bladerunner kit and 620 motors with 3.5:1 gearing is fine good sharp corners at speed as well.

Don't think I would change anything else though, worked out great, the raised side rails are a godsend for me, it really aids loading and moving sheets on the table ( 70mm tube as a roller and pry bar, can manover a full 8'x4' with ease)

[Jason Marsha]

Excellent work on the machine.

Thanks for posting the pics and your observations after 5 years.

Did you have any glitching issues due noise created by the plasma torch?

Jason