[mikeysp]

Why don't we see DIY machines for cutting steel? With the accuracy limitations of plasma and the cost of water jet and laser, I would think there would be a movement toward steel cutting router tables.

Here is a video Video of a guy cutting 1/2" steel on his machine, so it is doable. However, what about a little more purposefully built machine?

I must be missing something, since I don't see these machines being built. What am I missing?
Why don't we see machines like this?

Idea:

1. heavy gantry
2. low rpm spindle
3. tool cooling (air or liquid)

Thanks,

-Mike

PS. A couple days ago, I started a very similar thread in another section of CNC Zone, because I figured this was not a "router"; however, after zero interaction, I thought it might actually fit better here. I could not figure out how to move it, and PMd a moderator, but no answer. So, please forgive me if I committed Zone rule error.

[ger21]

Rigidity.
Rigidity.
Rigidity.

Why don't we see machines like this?

Because they just don't work very well.

1) V rollers imo are average at best for a wood router. They are no where near stiff enough for a metal cutting machine.
2) Mills can cut 5-10 times deeper per pass than what is being done in that video. A router is very inefficient at cutting steel.
3) Mills will give a vastly superior finish.
4) Mills will be much more accurate, due to their high rigidity.
5) Tool life will be much shorter on a less rigid machine, due to vibrations.

[mikeysp]

Thanks Gerry. Has anyone made a diy large format mill?

[wizard]

Why don't we see DIY machines for cutting steel? With the accuracy limitations of plasma and the cost of water jet and laser, I would think there would be a movement toward steel cutting router tables.

As was already mentioned the rigidity in most build simply isn't there. Beyond that a router for the most part runs at way too high of an RPM to deliver the versatility you need.

Video of a guy cutting 1/2" steel on his machine, so it is doable. However, what about a little more purposefully built machine?

"Doable" is a broad sword. As for purposefully built you can do that to any degree you want. You can actually buy bridge mills, planer mills and the like that are conceptually a lot like a router but these are massive machines designed for machining metals.

I must be missing something, since I don't see these machines being built. What am I missing?

The degree of rigidity required and the precision you would want to call it a milling machine replacement puts it out of the range of most home builders. It even puts it out of the range of many machine shops actually. Frankly I have to wonder what sort of tool life the guy in that video is getting and the finish look like crap even in the poor video.

Why don't we see machines like this?

Idea:

1. heavy gantry
2. low rpm spindle
3. tool cooling (air or liquid)

You can make one. Seriously, but it is a much bigger project than you imagine.

1. The whole machine will be heavy, probably much heavier than you imagine by 100 times. Router tables weigh in at hundreds of pounds, a milling machine with a large table will likely be many tons.
2. A spindle actually isn't a big deal as there are numerous companies that will sell you milling machine spindles.
   The costs of the spindles though is huge compared to what people shell out for a router.
3. Actually people would do well to add coolant/lube even to aluminum machining on a router. One of the reasons I suggest steel for a router build that will see aluminum machining is that you will want a water proof machine. There is one problem though, containment of the chips and wet stuff implies a totally enclosed machine. A totally enclosed machine adds to the build difficulty. Not only that but you need a way to recirculate the coolant, store it and ultimately dispose of it.

Thanks,

-Mike

PS. A couple days ago, I started a very similar thread in another section of CNC Zone, because I figured this was not a "router"; however, after zero interaction, I thought it might actually fit better here. I could not figure out how to move it, and PMd a moderator, but no answer. So, please forgive me if I committed Zone rule error.

I can't say why you got no response in the other forum but I might point out that some of the forums seem to by populated by people that like to shun others that aren't up to speed.
this forum is pretty good about that though admittedly I have my bad days.

Part of the problem is managing expectations. You can certainly do some cutting of steel on a router type machine if it is rigid enough. The problem is a lot of people don't understand how much of a compromise it is. Effectively you end up chewing up end mills and getting questionable quality in the resultant pieces. Also when it comes to expectations one needs to know what exactly one intends to do in steel, because tooling size is a huge factor as engraving and very small cutters can be used on a lighter framed machine. Lighter than a conventional mill anyways, but even for engraving you would need a rigid machine with good repeatability and resolution.

To put a different perspective on this consider that one can and does abuse a machine from time to time to accomplish a goal or grab an opportunity that pops up. That might mean throwing a massive casting on a Bridgeport, or trying to run a big annular cutter on a drill press that really doesn't have the power to do so properly. You do these things to get a job done knowing full well it is not ideal and frankly not sustainable. The same thing can be said for machining steel on a gantry router, you might get away with it but it is not sustainable and certainly isn't a replacement for a milling machine. This assumes of course that the router has any chance at all of actually machining the steel.

One last thing your drawing posted of the machine with "V" bearings set off alarms within my mind. It highlighted right away that you are not up to speed on rigidity requirements for a router. V bearing are at best a minimalist solution even for a wood router. There are some good stickies that are well worth your time spent reading that gets into design issue for a gantry machine.

[wizard]

Thanks Gerry. Has anyone made a diy large format mill?

Good question. There are lots of examples of small milling machines on the net that are interesting DIY projects. The problem with a large format machine suitable for milling steel is that such a machine requires a well equipped shop to build. You gantry would likely be multiple tons heavy and likewise the base of the machine will be heavier and huge. Here: http://www.haascnc.com/DOCLIB/datash...Rseries_US.pdf, is an example of a commercial machine that isn't even marketed for steel, instead focused on light materials like aluminum. Even so it is a pretty heavy machine.

[mikeysp]

Wizard, that was very helpful! I am planning to build a Mechmate, so that is where the v-rollers came from. Also, since the guy cutting the 1/2" was using a mechmate, I drew up v-rollers. I thought, why not make a few mods to make it more effective? However, your answer is very instructive. Thank you. You mentioned that there are some good stickies for me to read. What does that mean? Thanks, -Mike

[steve123]

My build will be an attempt at this (if I can ever finish it). Envelope 3x4.5'x7"z Table is 3x4'x8" granite surface plate, 1500 lbs. Gantry is 3x5"x3/8 steel tubing, 2 beams with webbing between, 3' wide, 135 lbs before sides attached. Will fill with sand + oil. Tormach 770 spindle and motor. DMM 750 watt servos. 20mm profile rail. Getting everything precise has been a real challenge. I have access to a small machine shop. I think it will work, but I haven't seen another one!

[mikeysp]

Steve, very interesting build indeed. That is a thoughtful idea. I think I am going to scrap the idea of a mill for now, and stick to the mechmate router and the very simple plasma table I have in mind. My real goal is to get to manufacturing items, so I will consider a used bridgeport sized machine down the road. Also, I may run a few tests when the mechmate is online. -

[run_cnc_at_home]

I built a mostly steel fixed gantry cnc router and I´m able to cut steel:
https://www.youtube.com/watch?v=XFp6yBcb4i4
https://www.youtube.com/watch?v=IsVqWVxyB5g

[peteeng]

Hi Run CNC - very impressive build and blog. Thanks you. I think its a high speed mill not a router! Merry Xmas - Peter

[routalot]

I wonder how well it will work when the spindle has done a couple of thousand hours of work.It looks like a rugged small machine.