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Discussion Starter #1
I'll start by saying that I've been around the board for about 11 years, but lost my other login, so I'm not a complete rookie.

Ive been wanting a CNC table for years. I can't justify buying a factory turnkey unit, and I like to build my own stuff. I'm ripping off ideas from the other builds here. I'd like to adapt both a plasma, as well as possibly a small router for wood engraving. The point is not only to have a new tool, but also as a leaning exercise. The first iteration will be 4x4 with the ability to expand to 4x8 if desired. The general plan so far is:

2x2 3/16wall tubing for rails, base and ganty
Nema 17 steppers
acme screw drives (not married to this idea and my go to timing belts)
Roller skate bearings for ganty and z axis trolly
Ardurino controller with drivers off amazon

I'm still trying to decide on a cutter. This is one area I don't plan to skimp, buy good and cry once. I just sold my little hobart airforce cutter and am looking at the hyperthem PM45. I don't ever run into cutting over 1/2" stuff so I think this will suit me well.

ANyone have any input, or want to tell me what I'm doing wrong?
 

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I wouldnt use the tube for your rails. Bolt some cold rolled bar to the tube for your bearings to ride on, much straighter and tighter tolerance.

I have a pm45 on my table. Great machine going on 3 years of near daily use. Thickest i cut with it is 3/8". Slow going but a great cut. If you do 1/2" i would move up to a pm65.
 

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Discussion Starter #4
I wouldnt use the tube for your rails. Bolt some cold rolled bar to the tube for your bearings to ride on, much straighter and tighter tolerance.

I have a pm45 on my table. Great machine going on 3 years of near daily use. Thickest i cut with it is 3/8". Slow going but a great cut. If you do 1/2" i would move up to a pm65.
I think I see what you are saying, use a flat bar to "plate" the rails? Not sure how I would attach it without interfering with the rollers, maybe button heads countersunk? Probably could go with a thinner wall tube in that case.

I most likely won't be cutting anything over 1/4" on any sort of regular basis. My brother in law has a bigggg hypertherm handheld that will handle 1" that I can use if I get into anything really crazy.
 

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Discussion Starter #5 (Edited)
Look into the PM45XP, just came out.
Will do, thanks

Edit:
Actually I guess that is what I was planning to buy. Price point just under $1900 on amazon and I have a butt ton of points saved up on my amazon card. We don't have any local welding shops worth a crap around here or I would buy from a brick and mortar.
 

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McMaster Carr has linear shafting for super cheap, along with proper bearings.

Linear shafts are hard chromed, ground and straight within a couple thousandths
 

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Discussion Starter #8
I did some more homework and think I'll just pick up these V slot linear rails for my x axis (and possibly Y). I already picked up some of the round style liners for the Z. I see the advantage to not using box tube and building my own trolley.

This seems like the easiest solution, as far as assembly and maintenance. Or am I on the completely wrong track? (pun intended)

https://www.amazon.com/V-Slot-Linea...F8&qid=1485706975&sr=8-7&keywords=linear+rail




Further homework also has me questioning the NEMA 17 steppers and I think I'm going to step up to NEMA 23. (pun also intended)
 

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I've been building desktop CNC and 3D printers for about 5 years. I'm looking at doing a lower power fiber laser as soon as the prices on the laser drop a bit more.

V-Slot works well. The thing that matters most with that config is the wheel quality. Open Builds do V-Slot well and have a community of DIY machine makers. Build List | OpenBuilds I've used all of the wheel materials and like the Extreme the best though the Delrin and all metal work well.

I've been replacing belt (usually using GT2 these days) with screws where I can. I would go with a NEMA 23 for anything bigger than a desktop machine. The four lead configuration screws are pretty fast under travel. The single lead and two lead type screws aren't as fast. I still have some belts on six 3D printers and a 6040 CO2 laser.

I've gone through over 1000 Arduino based building 3D printers. For a plasma or CNC with a larger, heavier gantry the stepper drivers may not deliver enough current and they do run hot even on a smaller machine. I've run pretty much all of the small format drivers and I'm most happy with the Pololu Black series ( https://www.pololu.com/product/2128 )though it likely isn't going to be enough to move larger, heavier gantries consistently. You can pull the signalling off of the board and not use the smaller drivers. Something like a DM556 or clone is a better choice. Leadshine Technology Co., Ltd.

Firmware on the 8 bit Arduino isn't the greatest these days, most are moving to a 32 bit solution, primarily the Smoothie based series. start [Smoothieware] The motion planning is far superior to anything available for 8 bit Arduino. There are a few boards that support Smoothie though the Smoothie board ( smoothieboard [Smoothieware] ) is a good choice though a more cost effective choice may be the boards from Cohesion 3D ( Cohesion3D Mini - Cohesion3D: Powerful Motion Control ).

For CAM and control software CNCWeb is coming along nicely. Current version is at https://github.com/LaserWeb/LaserWeb3 and the newest version, still in alpha is at https://github.com/LaserWeb/LaserWeb4 . You can also use a CAM that generates gcode and load it via Mach.

For some ideas on how to implement V-slot, screws and larger current motors on a 3 axis machine check out Shapeoko ( Carbide 3D )or some of the builds at Openbuilds. There has never been a better time to build DIY CNC machines.
 

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Discussion Starter #10
vegasloki, thanks for the advice and the link. I have been reading my ass off any watching youtube videos linked from there. I went ahead and ordered some v slot rail for the x and y axis. I think my plan is to build a steel table and attach the x axis rails to the steel frame, to help control deflection over the 5' run. I'm waiting on a gantry plate still to start mocking up the y axis to get measurements to bulild the table itself.
 

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The C and CNC packages are great. I know of some that are using them on their routers. It's plug and play ( plug and play as building this kind of thing gets...). By the time you get Mach it's a couple of grand but the install seems no fuss, no muss and you get THC. It's a good value.

You will save quite a bit in purchase cost piecing something together but you'll need to integrate and configure everything. That's going to be a big barrier for some as you need to know how to edit and load firmwares, config parameters and integrate it into the system. I could roll my own for a few hundred in parts, but no THC, build my own packaging, take care of my own cabling and put a non trivial amount of effort into it. Rolling your own is a project in and of itself.
 

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Discussion Starter #13
I'm going to give it a go with the ardurino controller. I learn pretty quick and this is a hobby type deal, so I'll figure out how to muddle through. The turnkey packaged are nice but for sure not in the cards for me right now on this project.
 

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Discussion Starter #14
I've been needing a drill press so I went to a semi local industrial surplus company and picked up this 1946 Delta. Not bad for $39.



While I was there poking around I ended up buying a truck and trailer load out of the stuff they were clearing way out. This caught my eye first.



Perfect rail for my gantry, nice box and mount for my monitor, and some spare 1/4" steel and aluminum plate. Not bad for $20.





Laying out the gantry plates on the reused mount from the control box.


The USPS was also nice enough to deliver my 80mmx1500mm v slot rails for the x axis, seen here with the recycled gantry.



I also ordered a gantry plate and wheel kit, mostly to get a template for drilling my larger gantry and y axis plates.



 

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Discussion Starter #15
Further poking around the surplus store and I found this thing. Pneumatic lifting clamp from a ford factory. I originally was attracted to it for the nice shackle on top, and it has some cool air valves I can use on another project. So I threw down $16 for it and loaded it up.



Looked a lil closer...


Score. Super nice linear slides. Perfect for a z axis.





Tomorrow I need to do some major shop cleanup, and order steel for the table itself on monday.
 

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Nice salvage yard scores. I wish we had more of that kind of salvage here in Vegas. I've got to ride into So Cal any sort of good industrial salvage.

Have you decided on electronics/firmware and software yet?
 

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Discussion Starter #17
Nice salvage yard scores. I wish we had more of that kind of salvage here in Vegas. I've got to ride into So Cal any sort of good industrial salvage.

Have you decided on electronics/firmware and software yet?
I went back today and loaded up on a bunch of hopper tables to cut up for donor angle iron, and other random crap...

Not really decided on what to go with. I know my original driver and stepper choices are going out the window. I'm thinking I'm going to go rack and pinion for the x/y and use a nema 23 with gear reduction for them. I'm not sure yet if I can get away with only one stepper on my X or if I will need 2. will prob use a regular nema 23 on the z.

I need to figure that out before I start building the physical table so I can take into account where and how the motors and rack will be mounted.
 

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I've got this configured and spinning motors

Arduino Uno w/4988 drivers as a test bed, led firing on M3 (torch enable) grbl firmware, Universal Gcode Sender as the controller, Fusion 360 as the CAM with a post processor one of the grbl devs wrote.

Inbound I have an Arduino CNC shield. Arduino CNC Shield – 100% GRBL Compatable | Protoneer.co.nz Rather than use the Pololu pins you can pick off the signal and send it to larger stand alone drivers.

Clone TB6600 4 amp drivers US Warehouse | TB6600 4A CNC 32 Segments 42V 42/57/86 Stepper Motor Driver Controller

Motors I haven't ordered (using NEMA 17 for the electronics test) but something along the lines of Kysan Electronics Product Detail Page

For controller and drivers I'm at about $85, motors another $180 or so retail but I can get Kysan wholesale, probably closer to $120.

Right now I'm using standalone SMC DC psu, one for the Arduino and shield and 24 volts for the motors. I'll likely swap them out for a DIN rail type to mount in a box with the rest of it.

The plan is to use a Raspberry Pi at the machine to run UGS that mounts a network drive I already use for the source and gcode files. I've been using the Pis for the print farm and the network drive for the printers and laser cutter. Works well, it's inexpensive and handy.
 
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