[octothorp]

First post. I've been lurking here for about a year, though, basking in the obvious brilliance of others. I'm just planning my first CNC router, which I plan to use for woodworking.
When I was in at the bearing shop buying some skate bearings, I noticed they had these cool things called kee-klamps (www.keeklamp.com); great weld-free way to quickly build solid structures out of pipes. And it got into my head that this would be a great way to build the frame of the CNC router. I'm already using gas pipe for the rails, why not build the whole structure out of gas pipe? It should be very sturdy, and it would allow me to build it just with the tools that I have (basically a drill press, a router, and a few smaller tools).
However, the big problem with kee-klamps is that they're really pricey. But I found I could make my own by buying regular pipe fittings, hollowing them out with a bit sized to the pipe diameter, and then drilling small cross-holes, tapping them, and inserting set screws; keeps the price at about $1.50 per fitting rather than around $10 per kee-klamp.
Anyway, before I actually start throwing things together, I wanted to get some feedback from the much more knowledgeable people on here: if I were to try to build an all-pipe CNC router, what problems could I expect to encounter, structurally? Are there problems with using pipe that I wouldn't get in a more conventional build (say, MDF, or square pipe)?

Many thanks!

[project5k]

thats an interesting thought, but it looks to me like all that machine work that your going to do would eat up loads of time, and you'd have to be very precise... making sure that this one is at a true right angle to the others... i say if you got what it takes, then go for it, post lots of pics for us, but i douldnt have the patients that it would take....nor the precision...

[octothorp]

thats an interesting thought, but it looks to me like all that machine work that your going to do would eat up loads of time, and you'd have to be very precise... making sure that this one is at a true right angle to the others... i say if you got what it takes, then go for it, post lots of pics for us, but i douldnt have the patients that it would take....nor the precision...

Time (moreso than money, knowledge, common-sense) is the one thing I have right now. But I made up a jig where I can machine one T-fitting in about eight minutes, so I could probably do most of the machining that I need in a day. As far as the level of precision, you're right about that being an issue. But I like the idea that I can make little adjustments to it fairly easily.

[project5k]

ahh i see your in the same boat that im in, more time and skills than $$... well then i say go for it... i would love to see that be a new "style" of build

[andy_ck87028]

A couple of comments.

First .... skate bearings are a dime a dozen via ebay ... go Abec 7's dirt cheap.

Second ... good idea with Keeklamp but an absolute key to cnc building is rigidity. I started building with metal; tapped holes and bolts and it was not rigid. I then bought an old arc welder (after much hesitation I must confess) and bingo! I also realised that absolute precision is not essential for much of the build and so providing you can adjust the position of the rails, don't worry about rough welds in the frame.
In summary, use the keeklamp for jointing purposes and a welder to make the joint rigid.

Andy

[wcarrothers1]

Weld free??? Take a moment and thing about what you are saying..

no welding? miss all that fun?

b/

[andy_ck87028]

Too cryptic for me b/

A bit more clarity pls in your comment then I can work out what side of the fence u r on.

Andy

[octothorp]

Maybe I'll have to look at adding welding to the list of things that CNC will force me to learn, then. I can just throw it all together, and then if I'm having problems with the rigidity, weld it at that point.

[project5k]

you can pick up an inexpensive fluxcore mig welder from homedepot for like 300 or so... and mig is by far the easiest welding to learn, its pretty much point and click... ok theres more to it than that, but really thats the basic idea....

[andy_ck87028]

Maybe I'll have to look at adding welding to the list of things that CNC will force me to learn, then. I can just throw it all together, and then if I'm having problems with the rigidity, weld it at that point.

Welding .... I'm a convert!!

Great fun ... really easy after a little practice.

I have bought a 30 year old copper cored arc welding jobby which cost me $85. Bomb proof ... designed to outlast me.

The new ones are not designed to last unless you pay big bucks. They are designed to be light now... mine is a heavy b****r ... 38Kg but it stays in the shed.

If u create a bad weld ... angle grinder .... make sure walls are min 3mm otherwise you'll blow holes in the material.

Very safe .... buy a cheap welding mask ... don't hesitate!!!!

I bought mine from ebay.

Andy

[wcarrothers1]

What I meant was welding I think is the method of choice for many of us. Because it's easy, quick and results in a stronger joint (I would say) then bolting and resists movement better then bolting would for most of us..

I will admit that I think at least some of my design will be bolt together. But the main legs and gantry rails on each side are all welded.. the table might end up bolt on between the rail supports just so the machine can be taken down and moved through a door if needed some day..

But then again when I get to the point where I'm building the table I might change my mind after spending time drilling the first few bolt holes...

b.

[project5k]

yea, the under table screw interface on mine will be bolt on, just incase i ever need/want to take the gantry off, but im planning on 3/8 bolts and plenty of them...

and you know its not the drilling part that bothers me, its the tapping, holding the tap straight while trying to start it allways gives me fits...

i have cheated a time or two and gotten away with it by putting a tap in a drill, but i know this is a major no no and yes i have broken a few taps this way...

[zippy]

Octothorp, I thought about going in a similar direction to make the build faster using pipes and fittings you can actually use threaded fittings for most of the joint's and modify a fitting for a slip and bolt conection for the last fitting in a square ect... but the fittings I find in stores like home depot and similar stores are cheap castings and only come close to square and don't really hold right angles. I say weld it if the members are heavy enough that you won't warp them silly I have a cheap harbor freight 115v mig welder you can get one for under $200 sure I wish I had a better one and controling the wire speed is more magic than science but you can get a strong weld if you don't mind how it looks.

[Geof]

Maybe I'll have to look at adding welding to the list of things that CNC will force me to learn, then. I can just throw it all together, and then if I'm having problems with the rigidity, weld it at that point.

It could be a good idea to do some test welding on the pipe fittings; as Zippy says they are cheap castings and some I have seen look much more like cast iron than steel. Cast iron cannot be welded effectively.

[Madclicker]

They are cast iron, and the proof is that they will crack if over-tightened. If you want to weld small pipe, use socket weld fittings not screw fittings.

[ger21]

How about bonding the fittings using epoxy. Should give similar strength to welding.

[project5k]

i disagree, welding is melting the 3 different metal parts into one moltent pool.. there by making them one... the epoxy will eventally either crack out, turn loose, or just fail outright... and welding cast can be a challenge, and actually can be done very effectivly with a tig welder, but thats a massive jump in skill and expense... you can "stick" a couple parts of cast together with a mig, but dont expect it to last, nor be as strong as a steel to steel weld...

[wcarrothers1]

Proj....

Make your self a tapjig from wood. Drill the wood and tap it. Place on what you are taping and it will hold the tap streight as you start the tap..

The jig will not last for ever but it can help keep it streight while it lasts.. Then just make a new one.

I've taped more threads in the last few months then I ever thought I would have in my life.. Most challenge was tapping the holes in my 1" steel bar.. But that was more a drilling learining process then actually using the tap. course you find if you didn't properly drill all the way past the hardened part of the shaft the tap tells ya pretty fast.

Also if you are Mig welding... I suggest you spend the extra 100 or so bucks so for the Gas kit rather then using the rosin core type mig wire. Using solid core Mig wire and separate shielding gas makes welding easier...

Costs maybe 30 bucks for a 10lb tank of co2/argon mix and maybe 20 bucks for a fill where I go. A fill will last long enough to weld most gantry mills completely. (filled mine when I started my project and it's still going)...

I didn't like welding with the cored mig wire..

b.

[Madclicker]

The core is flux, not rosin. The process is flux core welding. When you use gas then use the cheaper solid wire. Then the process is MIG (metal inert gas).

[zippy]

all the splatter with flux core is a pain but it is a little cheaper for starting since you don't have to get a regulater. Granted the consumables are more expensive and more toxic