Cabinet design question

[Dave Cottrell]

I want to make a mobile stand for my milling machine. It is one of the "benchtop" types that weighs about 600 lbs. I would like to make a stand that is moveable when needed, would minimize vibrations, and would raise the working height from its current 3 feet to about 4 feet off the floor ( I am around 6 foot and like to have higher-than-most working surfaces).

1. What would be the best type of carcase? I am guessing a frame of 2x4's with a skin of 3/4 MDF. Heavy is good as it lowers the center of gravity and I don't have to worry about tipping the whole shebang over. I am guessing the frame should be mortise/tenon joints. The MDF skin is there for weight and dampening, but I would also like drawers inside the cabinet.

2. Mobility -- one of the Shop- Fox type bases? Suggestions needed here.

I have limited cabinetry experience as most of my woodworking consists of small items (violins, accordions, etc.). I built a butt-jointed drill press stand and a lap-jointed workbench, so this would be another step up the learning curve. Please make suggestions and corrections to my assumptions. Thanks

[Joe Chritz]

I would opt for a 1x2 steel tube frame, welded and painted.

Properly supported and constructed 2x4 should hold the weight great but when you start moving it there is a lot of mass up high on those units. That is a lot of racking force.

If you are going for wood the M&T joint would be a great choice. Also I would go with 1/2 plywood skins in place of MDF. At least it is structurally rated for shear loads.

Joe

[Bill White]

Just make sure that the base has enough "footprint" to resist tipping.
My RAS is on a rolling stand, and I built it wide and deep for that reason. "No tippy, me happy".
Bill

[Jamie Buxton]

Except for the drawer requirement, you could build a stand for a 600 pound machine from 1/2" plywood. The stand would be a closed box, glued along all the edges. It would be just fine under that load. The difficulty comes with the drawers. If you were to build the stand like a Eurostyle kitchen cabinet -- that is, remove the entire front panel -- the front of the stand would rack if you pushed sideways on it. Instead, put a really sturdy face-frame on it. You could make the face frame with your 2x4s, and even make the top rail a 2x6. You can do nice corner joinery on the face frame if you like, but simply lapping the members over each other and gluing&screwing them together will suffice. And if you really want to use 3/4" MDF for the rest of the stand, that's okay too.

[Dave Cottrell]

Jamie Buxton wrote:
"Instead, put a really sturdy face-frame on it. You could make the face frame with your 2x4s, and even make the top rail a 2x6."

Am I correct in assuming the more cross braces, ie the more face between drawers, the less likely racking is to occur? 3 drawers (2 braces) better than 2 (only one)? 4 better than 3?

Joe Chritz wrote:
"I would opt for a 1x2 steel tube frame, welded and painted."

I wish. I haven't gotten around to learning welding yet.

Thanks for the replies.

[Larry Edgerton]

Dave, My brother and I have one of those small milling machines, sounds about the same size. I agree with Joe, and that is what we ended up doing, but we have welding equipment.

Look for a suitable metal stand from industrail scrappers?

If you build it out of wood I would use a hard hardwood, say white oak, and make a heavy, mortise and tenon frame using epoxy at the joints. That will allow your drawers without racking and still be wood. From my conversations with machinists vibration really affects quality and cutter life, so I would still think about steel.

[Jamie Buxton]

...Am I correct in assuming the more cross braces, ie the more face between drawers, the less likely racking is to occur? 3 drawers (2 braces) better than 2 (only one)? 4 better than 3?
...

If the rails between the drawers are the usual half or three quarters of an inch tall, they won't add a great deal of stiffness to the face frame. Mostly what will hold it square are the big joints at the corners between the 2x4s.

I didn't mention, but the 2x4s (or 2x6 across the top) should be oriented so that the "2" dimension runs front-to-back. This makes them stiffest in the direction you need stiffness.

[Chip Lindley]

I just would not take a chance on hit-or-miss woodworking to make a frame for a machine this large. Welded (or bolted) steel is much more appropriate than softwood 2x4s. Any attachment of wheels or casters may shift or loosen over time in soft wood. 3x3 angle might be a good place to start. I have scarfed up lots of the stuff cheap at a friendly recycler aka *junkyard*!! Amazing what you can find that consumers and businesses have no use for.

[Joe Chritz]

Jamie Buxton wrote:
"Instead, put a really sturdy face-frame on it. You could make the face frame with your 2x4s, and even make the top rail a 2x6."

Am I correct in assuming the more cross braces, ie the more face between drawers, the less likely racking is to occur? 3 drawers (2 braces) better than 2 (only one)? 4 better than 3?

Joe Chritz wrote:
"I would opt for a 1x2 steel tube frame, welded and painted."

I wish. I haven't gotten around to learning welding yet.

Thanks for the replies.

No time like the present. ;)

The other replies are very good. A solid half lap would suffice for strength and as mentioned, racking is the main concern.

Joe