Good evening all!
I am planning out my next project and have decided I am building the rat rod of vertical machining centered.
First I was considering buying an X2 style mini mill. I then spotted a smoking deal for a RF-30 style machine and jumped on it without hesitation. After loading it up, on the way home I started putting thought into this machine and realized it is a terrible candidate for CNC being a column type machine you could only use the quill for a z axis. My suspicions were confirmed when I arrived home and realized people have the exact issue I feared. The machine is an excellent addition to my garage so I decided to keep it for light manual work and accurate drilling operations and move on to another platform. Again I was looking at the bench top options and had settle on a Precision Mathews when I realized I was paying $2500 for a dovetail machine then most likely another 2 grand on the low end to outfit her with CNC gear.
It was at this point I was feeling a little frustrated. I hate paying for an expensive thing and then replacing almost every part of it. It seems silly to tear apart a perfectly good machine and replace brand new parts. I could toss them on a shelf and wait for the day I never used them again.
I start to price steel for a more traditional type of build. Some quick math brought me to a total of 10k, maybe more. Wasn't I just looking at a $600 machine to outfit with $400 worth of electronics and another $200-$500 worth of random hardware into a itty bitty table top machining center?
Then it hits me. Man there are a lot of big chunks of structural steel out there no one wants that can be had for less than the price of scrap. Why not build a frame that is total overkill, outfit it with decent linear rails forgoing dovetail ways, and put some electronics on it I am familiar and comfortable operating?
So here is the plan. I Beams! They are everywhere and incredibly cheap. I have some pals that can probably straighten out the rail mounting surfaces once I get done warping the daylights out of them with my old Airco TIg/stick welder (Lets stick weld a precision machine!!!!). I will use mostly Chinese linear motion stuff. I have a sizable router table that was built from 80/20 profiles and Chinese SBR20 rails I can easily machine steel on with the right feed/speed recipe, so HGR style rails should do the trick. I have been looking at the different rails and see them up to and in excess of 45 mm width. BUT they get exponentially more expensive which I am assuming is due to the much lower demand for heavy duty rails. What if I were able to double up some smaller rails such as HGR15's as opposed to going with bigger rails? So in place of the traditional 2 rows of linear rails I would use four rows of smaller rails. I know it will require extra careful layout to get everything running straight, but it seems more than doable.
I guess my question is will four rows of 15mm linear rails be enough to machine steel on a small and rigid platform? Or should I buck up the cash and buy some manly 35-45mm rails and call it a day? For a fraction of the cost I might just be willing to try doubling down!