Help with low budget cnc build.

[UFO8MyCow]

As the title suggests I am looking to build a small 3x3 ot 4x4 low budget cnc plasma table that would see light use in a maintenance environment and of course a few government jobs to keep it from feeling under appreciated. I would like to keep it under $1000 not including the computer and plasma.

I am planning to build the table and gantry out of square or rectangular steel tubing and using v groove bearings and direct drive rack & pinion for the motion, but I have also considered acme screw drive on the X axis for the extra torq without needing gear reduction, and sticking with rack & pinion on the Y

I have been looking at buying 4 axis kit from either probotix or automation technologies (links below) I also checked with candcnc but they are out of my price range.

I spoke with probotix and he recomended the kit with the pbx-rf breakout board and would be $500
4-Axis Monster CNC Stepper Motor Driver Kit - 4-Axis Monster CNC Stepper Motor Driver Kit

I tried to talk to talk to automation technologies but just became more confused. The kit they offer with the 400 in motors would be $465
4-Axis NEMA23 CNC Kit (36V/9.7A/ 425 oz-in/ KL4030) | Automation Technology Inc

I'm also curious how essential the auto torch height is. can I just set the height manually and possibly purchase a thc later

I also need to figure out what software I need. I have autocad lt that I will use for design and I was planning on useing mach3 to run the machine but I need somthing to convert the cad files to g code. Are there any decent free or almost free programs?

[jimcolt]

I suggest talking with www.candcnc.com , they have the most experience with do it yourself cnc equipment, and will steer you in the right direction for your build. Check out their web site.

Jim Colt

[chasxjs]

I commend you in wanting to build your own table. It is an excellent way to fully understand the workings of the machine in a very short period of time.
However, do prepare yourself for some frustrating moments getting everything worked out. This is one area where good vendor support would be very helpful. Which is not to say it can't be done on a budget. I just suggesting you spend some time on research before you invest anything. Everyone I know that has tried to go the cheap route, ended up giving up or spending money on up-grades to the point that their investment was equal to or even higher than it would have cost to build it the way they really wanted it to work in the first place.

As far as torch height control:
It can be operated without one and a lot of people start out that way. But, it requires the table to be built to much closer tolerances and operated in a way to keep material warpage to an absolute minimum. I would definitely recommend that you budget for a torch height control and some form of automatic zero on the Z axis. It is something that you would likely make your first up-grade anyway.

Now where software is concerned:
AutoCad is probably great for the maintenance stuff you mentioned. However, if you expand into the more artsy stuff, you may find that Inkscape is easier to work with. It's a very a popular program for drawing/design work and fits into your free category.
I would definitely recommend you go with Sheetcam for generating your g-code (Not free but worth the cost).

[beefy]

A cnc table for under 1K is just about free.

I'd set up a spreadsheet and put every little item you have to buy in there. See if you can get the cost to stay under your 1K budget. Every single nut, bolt, bearing, etc for you to end up with a complete table.

Lots of newcomers want to do without the torch height control. Some things to consider - the table would need to be built very accurately as has already been said. The top of your slats would have to be perfectly flat all over to an imaginary horizontal plane that is parallel with your X and Y axis. If you are wanting paid jobs as you have said then I'm guessing you'll need decent edge quality, and that is likely quite difficult to get without a THC. A bit of slag on the slats and your height accuracy is gone. Thin metal warps with the heat but your torch will just stubbornly stay at the same height and not compensate. My Hypertherm cuts at 1.5mm above the metal, doesn't take much to mess that up. Many consider the THC to not be an option with plasma cutting. A THC with touch off facility allows the torch to pierce at a greater height then come down to cut height for the main cut, then exactly maintain that height. You may find your nozzles are stuffing up more if you can't pierce at a higher height (= spending money).

I'd see if anyone has built a table within your budget, and ask if they can give you an explanation of how they did it (I'd like to know ) and how well their table works. Be careful of those with too much pride that just want to show off their $10 and say it works great, when it's actually not that good.

A problem with leadscrews instead of rack and pinion or chain drive, is whip. At higher cutting speeds I've heard the centrifugal force can cause them to do a skipping rope action.

Keith.

[suttoncnc]

Don't want to discourage you at all but.............I think your budget is a little unrealistic. I designed and built my own 4 X 4 table and used as many parts as I could scrounge. I still came in around $3500.00 for everything including software and computer. IMHO, THC is really not an option....especially for cutting thinner material. Take your time, build it right, use the information here and then be satisfied with a great cutter for many years to come.

Scott

[Largemouthlou]

On the electronics,,,, you get what ya pay for!!

[TJS]

We do not know your fabrication skills or the tools you have at bay. After working on my PPLC project for a year now. I have used almost every tool and machine tool in my home shop. I have a Bridgeport Mill with DRO, South Bend Lathe, hand held plasma cutter, 240 AMP MIG welder, 300 AMP Miller Dynasty TIG machine, Band saws(horizontal, verticle), Small sheet metal brake (home made), hydraulic tubing bender,Chop saw and tons of cutters, drills and taps, etc.

Even with a PPLC kit I have found you have to make all the anciliary stuff to make even the kits work. I have to make every little bracket or mount that I need. I know people have done it without these tools but that is a great feat in it self.

[kkroger]

I would take a look at the smaller formats that Precision Plasma LLC offers, he has them down to 2x2 IIRC
Then the electrics and software from CandCNC...

[acourtjester]

Many opinions provide a great basic starting point and there is a very large pool of knowledge here.

[Nacs Fab]

I do recommend the Gecko 540 controller and the http://www.cancnc.com LCTHC with Interface Card. This is their low cost torch height control and it does and excellent job for the money. http://candcnc.net/index.php/spare-part ... ler-detail I could not find the G540 Interface Card, but its not needed to save you a few bucks - just simplifies the install. I would not recommend trying to cut anything at all without THC. I use it to maintain my nozzle distance to work so that all of my cuts are as best they can be.

If you want cables, I have 4 that I would sell cheap for your motors. They are 12' long from CNC Router Parts and are nice, shielded cables - I just bought longer cables after re-configuring my 4x8 machine. PM if interested.

A company called Keling is who I sourced my G540, motors and power supply from. Cheapest around and good quality. http://www.kelinginc.net/CNCNEMA23G540Package.html I have kit #3. Actually... They have changed names... here is my kit: http://www.automationtechnologiesinc.co ... in-48v7-3a I went ahead and bought my controller box from them as well - already made for G540.


That would get you into an electronics package with THC - also having your board to connect to your plasma cutter for $770 ($495 plus $275).

One thing not always mentioned - buy a computer that is at least 3ghz processor. I chased faults for 2 years due to having a cheaper PC. No more problems with the bigger PC. Mach3 is sending out/back tons of data and you need processing power!

All of this being said - i do wish I would have dropped the coin on a bladerunner package from candcnc.com. It makes it much easier in the future when you want to add other features such as a laser crosshair and scribe or any other accessory because they have multiple relays built in. The above will not get you an additional relay unless you get that G540 Interface Card i spoke of. There are other features I love about their system as well. Tom himself commented on my build over at cnczone.com and said basically its a shame such a precise piece of equipment, has such low end electronics - I can say I do agree with him.

[vmax549]

You can build a low cost small table IF you are clever and can take advice well (;-).

With the rack and pinion you WILL need a gear reduction of about 3:1 -5:1 to move the gantry well. On the Z you will need a COURSE screw for speed on the Z.

The Guide ways can be a piece of square stock and use small ball bearings to guide the gantry.

DO NOT even think of chinese drives to save money. THe gecko drives are the way to go .

THC, NICE but not required for such a small table. You can manage for a while without it, You just have to be clever and pay attention when you are cutting. With Mach3 you can adjust the Z by hotkeys as you go. For low production it is not to bad to deal with. I know a few folks that have been cutting for about 20 years now and they can not even spell THC much less use one.

Just do not expect a high end build for your budget amount. There will be a LOT of hand crafting and not buying premade stuff.

Just a thought, (;-) TP

[UFO8MyCow]

Thanks for all the replies and advice. I guess I should have specified some my capabilities. I have a pretty we'll setup maintenance shop with a bridgeport, 15x36 lathe, mig, tig, stick welders and of course a plasma cutter.

I still haven't even talked to my boss about this yet so the $1000 budget would just be an easy sell. Now I am starting to think I may need to go more like $2500 to get a decent setup.

Now that I have been convinced that the thc is pretty much mandatory I have been looking at candcnc again and since they include the THC the prices don't seem as bad. I am looking at the Plasma - AIO BladeRunner Dragon Cut 620-4 Stepper System + DTHC II

http://www.candcnc.net/index.php/plug-n ... 0-4-detail

So for the kit, the hookup kit for the plasma and the software bundle with mach3 and sheetcam it will come to just over $2000

[I Lean]

I would recommend the CandCNC parts--that Bladerunner setup is exactly what I run. I consider it money WELL spent.

[tnbndr]

think I may need to go more like $2500 to get a decent setup.

In this price range there is a member here, I think it was tmamerica that is building lower priced tables. May want to contact him. I think he had an ad in the classifieds. You can search for his posts.

[blackandtan]

I would definitely recommend CandCNC we have two of their systems and they work perfect and you cant beat the customer service.

[Doc Hollywood]

Like above, pm tmamerica. He builds a neat table for about 3 grand.

[tm america]

i have been building them for about 6 yrs now and i specialize in building them for the lowest possible price .. what you are looking to do is not in the realm of what can be done..first off rack and pinion is the second most expensive way to do linear motion next to linear actuators.Metal v wheels are a bit pricey to especially when they have to ride on a hardened rail to keep the tolerances. next thing is electronics you can get a cheap controller- motor and power supply from ebay for around 200 bucks for a 3 axis but then you need to buy mach3 , a xp computer,cad -cam software.these are just a few of the issues you need to deal with.To me a auto torch height controller is a must for any cnc plasma table bigger than 2x2..even with a water table metal will heat warp and make you waste a lot of parts and consumables if you don't have it..if you can keep it under 2000 bucks you did something very special..

[Gamelord]

IMO, a plasma table without a proper THC is worthless.

[davek0974]

Two things I can suggest....


Torch height controller by CandCNC,

Hypertherm Plasma cutter.

Get that sorted in the budget and the rest is a walk in the park, basic mechanics.

I wasted ???? and weeks or months trying to get my small build working on a non-Hypertherm torch and super cheap THC, I nearly gave up and binned the idea.

Then in a last minute of madness I paid out for a Hypertherm 30XP and CandCNC THC system, never looked back

You will need dry compressed air too.

Good luck