MiniMax FS30 shopbuilt prototype mobile base FAIL.

[John Sanford]

So I spent a fair bit of time today working on my shopbuilt mobile base for Uncle Max. Unfortunately, I suffered a problem, or more accurately a near catastrophic failure.

This is the J/P on the mobile base is this first pic. The machine sits on its own feet when on the ground, lever action lifts the base, and then the machine, and away we go. At least, that's the theory.
Big Max Mobile Base.jpg

While testing the lift/lever action, gremlins attacked, as shown in the second pic.
Big MaxMobile Base Fail.jpg

The entire mobile base is 1.5" thick Douglas Fir, casters are 4", bolted through the DF. The levers are also bolted through the DF. As the pic shows, the caster "plank" failed along the grain line, which coincided with some of the bolt holes.

So, I'm coming here to plumb the collected wisdom of the Creek. I've two problems. The first is the failed plank. I see these possible solutions:

1. Replace with a new plank, i.e. go with the assumption that the plank was a weak one.
2. Replace with a new plank and make sure that the bolt holes do not align across the same grain
3. Glue up a new plank with grain running "fore - aft" rather than across as the existing failed plank.
4. Glue up a double thickness of plywood for a plank.
5. Something else??? Explain.

My second problem is how to lock the caster planks down. Any suggestions?

[Rod Sheridan]

John, I doubt if you'll want to go that route, however this is what I built for my jointer/planer.

http://www.sawmillcreek.org/showthre...31+mobile+base

Another option is to drill 2 holes, put an axle through it with two wheels and add two fixed feet to it.

This converts it to a semi-live skid design which is superior to almost everything out there. It's how the manufacturers put mobility into those machines.......Regards, Rod.

[Dan Hunkele]

Those are locking casters. Scrap the lift base mount the casters and use the locks to hold in place while using.

[Mark Carlson]

I'd get a set of leveling casters rated for the weight of your machine. No lift base needed. Thats what I did anyways.

[Erik Loza]

John, it looks like your design used a board as a fulcrum and that the fulcrum point was perpendicular to grain of the wood, so the strength of that board was negated or non-existent in the first place.

What about just use a piece of 3/4" ply under the machine and some locking/leveling casters like Zambus or Great Lakes? Or a metal kit as others have mentioned? The HTC-300 would fit your FS30.

Best of luck,

Erik Loza
Minimax USA

[Phil Thien]

Double layer of plywood.

I hope those hinges are held with machine screws and nuts.

[Mike Wilkins]

Wood is not a good choice for mobile bases under heavy machinery. If you do not have welding capabilities or access to one, the Shop Fox bases are OK. I have one under my 18" bandsaw. When you move it to the desired location, you screw 2 bolt handles that places feet on the floor, immobilizing the machine. These are universal bases designed to fit under many types of machines, so the fit will not be perfect.
Check the Grizzly site or catalog for these bases.

[Jim Matthews]

Double layer of plywood.

I hope those hinges are held with machine screws and nuts.

+1 on this.

I think it will work, you aligned the through holes
with the grain on pine - hence the clean fracture.

Plywood has crossgrain plies, and is immensely strong.

[mreza Salav]

Double layer of plywood.

[Erik Christensen]

i have a very similar setup for my hand tool workbench - i just have the levers on both ends so that when it is down there is no load on any wheel (bench 100% rests on the base). the bench fully loaded is over 1,500#. I laminated up 3 layers of 3/4" bb in my veneer press and cut the levers out of that - i think I could park my SUV on the bench and the levers would not fail .

[John Sanford]

Sorry folks, I'm so deep in the weeds on this that I failed to describe the limitations in play.

1. Store Bought Metal Base - It was sitting on one, of unknown (to me) provenance, but not a Delta/delta clone Universal. The base flexes WAY too much. I have 4 other machines on "universal" bases, every single one of them has inadequate ground clearance for clearing the garage/driveway transition without drama. Since the other machines are all much lighter, and are shorter, I can just muscle them over the threshold, although I know doing so is doing no favors to the base. boo hoo. I also know that there's no way I'll be able to do that with Uncle Max, as he weighs in at 540lbs, and has a longer base. I've not seen any store bought bases that have more than about a 1/2" of clearance.
   
2. Custom Metal Base - I don't weld, don't know anybody here who does, and don't have the funds at this time to pay to have a metal base built. A metal base is actually my preferred solution, and there's a good chance that the casters from this base will be cannibalized down the road to make one. Simply bolting up a metal base will risk more flex than I'm willing to put up with right now.
   
3. Leveling Casters - Love the idea of the Zambus (style) casters, but they would result in high centering at the garage/driveway threshold. I need to be able to easily lift the machine at least a 1.5 inches for clearance.
   
4. Direct locking casters, no "lift" - This would raise the jointer too high. While it would make using the planer a bit more convenient, control on the jointer is more important than a marginal improvement in planing convenience.

A semi-live skid design sounds good, but it still faces the problem of getting the machine up off the fixed feet, and providing sufficient clearance to avoid high centering.

The hinges are currently mounted only with screws (proof of concept), and haven't had any problems with that, but I had decided before posting my question to replace some of the screws with through bolts. Since I don't have to worry about "full closed" bolts won't present any interference issues.

I'm going to give it a shot first with an Option 3 plank before I drop any more money on this. I think I've figured out how to lock the planks down automagically and easily. If Option 3 fails, then I'll give plywood a shot.

[David Wong]

I have my Hammer A3-31 on a Rockler all-terrain base. The 4 inch wheels work very well, but I do not think this base would be adequate for your requirement of having 1.5" of ground clearance. I also have a metal base I fabricated for my 600+ lb bandsaw that uses leveling casters. The leveling casters have small 2" wheels, that would struggle rolling over a garage threshold. Your best bet would be to custom build a base using large diameter wheels.

One other thing... Your picture seems to shows the plywood base only supporting the center portion of the machine. IMHO, this is a dangerous configuration. If the machine does not have its weight centered, the machine could easily tip over. Don't ask me how I know.

[Keith Weber]

I've never understood the use of homemade wooden mobility kits on heavy machinery. As others have said, you can buy a metal mobile base like the Shop Fox, but nothing beats the ability to weld and make a proper base. I welded bases for most of my machines. If they don't roll on heavy duty casters, they're designed to rest on leveling pads with room for a pallet jack to get under them. Once you buy a welder, only the first project is expensive. After that, the others cost next to nothing.

Keith

[Jim Matthews]

I would suggest an alternative to permanent casters in the form of a permanent plywood base
and galvanized pipe "rollers" beneath.

With three 1" OD pipe rollers, you could easily hoist the machine
high enough to slide them under and glide across the floor.

Once you reach the resting positions, remove the rollers and let
the machine sit on the plywood base.

rollers.JPG

[Cary Falk]

1. Direct locking casters, no "lift" - This would raise the jointer too high. While it would make using the planer a bit more convenient, control on the jointer is more important than a marginal improvement in planing convenience.

It doesn't have to. I made t his many years ago. If my Unisaw wasn't around 540lbs it sure was wall over when I stood on it a couple of times. Rock solid. I weld all my bases now because I can but this one worked great.