Building stands and putting CNC machines on wheels

[Goemon]

Is it a good idea to build CNC machines on wheels like one of those mobile machine carts?

It seems like it would be a no-brainer for any build that is going into a home or small business given how hard it would be to move a CNC machine that wasn't on wheels. I have seen some examples of where people have done this but it doesn't seem to be common practice. Is it because it would causes stability or vibration issues?

You never see any of those Bridgeport type vertical knee mills on rolling stands and given how heavy and hard to move they are, I am assuming there must be a good reason why they aren't on locking casters?

I know there are casters designed to hold heavy machinery because my industrial heavy-duty laminators are on rolling stands and they weigh multiple tons. It makes it so easy and convenient to move them. Also, machines on wheels are a lot easier to sell for obvious reasons.

Do you guys use casters for your CNC builds?

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[Jim Dawson]

Not going to say I would recommend this, but here is a 4500 lb CNC on wheels. This came into my shop as shown, I didn't put it on wheels, but it seems to work. Two people can roll it around the shop. The angles are 3x4x3/8, attached with 3/8 cap screws. Not sure what the castors are. Screw down the jack screws to stabilize.

[Goemon]

That looks awesome! how many people avoid buying quality mills in favor of small benchtop machines because they can't be bothered for the hassle and cost of moving them into their homes....

What stops you recommending it if I works? Are there some noticeable problems caused by the wheels?

I was thinking that, even if the machine is on wheels, you can still bolt it to the floor or wall where you are done moving it. It's not like people will take their CNC mill for a walk instead of the dog.

[Jim Dawson]

That is a lot of machine to have on wheels, but there are no problems that I know of, seems stable. The mounting angles seem a bit light to me, but they work. The machine does move a bit if the jack screws are not set.

[wizard]

Lost my first reply (cell phone).

There is nothing wrong with putting machines on wheels for mobility, i would not hoever suggest running the while on those wheels.

There are two problems with wheels and machine operation. The first is that floors arent flat and router frames are not perfectly stiff. This means that the frame will twist to conform to the floor or try too. A twisted frame is bad but you can manage that with simple leveling feet. For example: Leveling Devices (ANSI & Metric) | Vlier Leveling Devices. The second problem is machine walking during operation that is when you buy feet with rubber pads.

I linked to the Vlier site but i need to say i don't like those types of feet on machines of any size as the studs are easy to bend. There are other types of feet that are somewhat more resistant to bending and you can even get leveling castors big enough for the job. Unfortunately looking for examples crashed my phones browser so no links at the moment.

Leveling your machine after a move is very important in my mind as an induced twist will show up in your work. Obviously machine size here is a factor, as is machine stiffness but you are far better off with a leveled machine before putting it into production. Some people can get away with a twisted machine but i don't see you doing that while trying to turn a router into a mold making machine. By the way we are talking precision leveling here.

So wheels are good and even better if the frame is designed from the ground up to support the wheels and the jack screws to stabilize it. You might be aware but there are a number of sub frames sold for wood working machinery to supply the machines with castors. Some of these are excellent but many are flimsy and frankly a safety issue. Designing in your own solution should make the castors mechanically strong to the frame. So that isnt an issue. The next problem is one of stability which requires more thought. A machine on wheels can be subject to tipping forces not seen in a stationary machine so you really want to consider machine stability when rolled around. For most routers this probably isn't a huge problem but might be on a long narrow machine. A floor standing drill press on wheels is an extreme example of a top heavy machine that could easily roll over during a move. I only mention this due to having to repair rolled over machines, machines that where top heavy and relatively narrow.

[Goemon]

Lost my first reply (cell phone).

There is nothing wrong with putting machines on wheels for mobility, i would not hoever suggest running the while on those wheels.

There are two problems with wheels and machine operation. The first is that floors arent flat and router frames are not perfectly stiff. This means that the frame will twist to conform to the floor or try too. A twisted frame is bad but you can manage that with simple leveling feet. For example: Leveling Devices (ANSI & Metric) | Vlier Leveling Devices. The second problem is machine walking during operation that is when you buy feet with rubber pads.

I linked to the Vlier site but i need to say i don't like those types of feet on machines of any size as the studs are easy to bend. There are other types of feet that are somewhat more resistant to bending and you can even get leveling castors big enough for the job. Unfortunately looking for examples crashed my phones browser so no links at the moment.

Leveling your machine after a move is very important in my mind as an induced twist will show up in your work. Obviously machine size here is a factor, as is machine stiffness but you are far better off with a leveled machine before putting it into production. Some people can get away with a twisted machine but i don't see you doing that while trying to turn a router into a mold making machine. By the way we are talking precision leveling here.

So wheels are good and even better if the frame is designed from the ground up to support the wheels and the jack screws to stabilize it. You might be aware but there are a number of sub frames sold for wood working machinery to supply the machines with castors. Some of these are excellent but many are flimsy and frankly a safety issue. Designing in your own solution should make the castors mechanically strong to the frame. So that isnt an issue. The next problem is one of stability which requires more thought. A machine on wheels can be subject to tipping forces not seen in a stationary machine so you really want to consider machine stability when rolled around. For most routers this probably isn't a huge problem but might be on a long narrow machine. A floor standing drill press on wheels is an extreme example of a top heavy machine that could easily roll over during a move. I only mention this due to having to repair rolled over machines, machines that where top heavy and relatively narrow.

I have heavy-duty leveling casters on some of my other machines (not CNC) and while the leveling mechanisms aren't massively sophisticated, they aren't that different to the regular leveling feet sold for CNC machines. I don't know what constitutes "precision leveling" but the process I will end up using to level my machine is likely to be the same with either machine feet or casters.

I hadn't though too much about how the rigidity of the stand would impact leveling. I can visualize the problem you describe but I don't understand why the issue would be different with leveling casters instead of leveling feet? I.e. If the frame is going to twist under the machine weight then wouldn't that happen with machine feet too?

I bought a steel machine stand / table which apparently holds 2000lb but I am not sure I want to use it as it seems like it would cause too much noise (it vibrates a lot). Maybe it would be better to skip the stand and rest the machine frame on the floor with casters. This would potentially eliminate any stand twisting issues. I have no concerns about the main machine frame structure twisting given what it's made of and the one-piece design.

The main base (that the gantry and moving table are attached to is 2' x 4' so I can't see it tipping over especially if it's fairly low to the ground. It's just too heavy to tip by accident.

For the potential issue with the machine moving (if the wheel locking mechanism is not heavy duty enough), I am assuming that this is solved by bolting the machine to the floor and / or wall.

I can't think of an easy way for me to remove the casters when the machine is not being moved. The main reason for wanting them is that the machine is too heavy for me to ever move without wheels. I guess I could buy a bunch of car jacks and build the underside of the base with gaps to slide them under to lift the machine enough so I could attach casters when I needed to move it. It sounds like that is unnecessary if the machine is rigid enough and designed properly to accept casters though.

Basically, just about anything I can think of that might be needed to make casters work sounds easier, cheaper and more appealing than getting a forklift license and renting a forklift truck to move the machine or hiring someone else to do it.

[awerby]

You could also put leveling feet on it as well as casters, so that when you had it where you wanted it, you could turn the leveling screws until the thing was level on its feet. If you wanted to roll it around some more, just turn them the other direction.

[dillonfitz]

My machine weighs around 4500 and it’s on wheels. The floor is flat, the machine is straight, however I keep it chained to the floor. I only take off the chains when I need to get to the back of it.


Sent from my iPhone using Tapatalk

[Goemon]

You could also put leveling feet on it as well as casters, so that when you had it where you wanted it, you could turn the leveling screws until the thing was level on its feet. If you wanted to roll it around some more, just turn them the other direction.

What would be the point? Leveling feet and leveling casters do the same job. Are you suggesting that the leveling feet be used as built in jacks to take the machine off the wheels when it's not being moved?

[ger21]

Machines that move at a halfway decent speed, will be moving all over the place while running, if they are on casters.

[awerby]

What would be the point? Leveling feet and leveling casters do the same job. Are you suggesting that the leveling feet be used as built in jacks to take the machine off the wheels when it's not being moved?

I was thinking the feet would supplement regular casters, not the leveling kind or the ones with brakes. And yes, they would lift the machine off the wheels, which even if they do have brakes and levelers, still aren't as sturdy as feet for running a CNC on.