Attaching smart casters to a platform

[CLEFFEL]

Sorry about the simple questions recently, it's just been forever since I've done most of this, and now my wife is teaching high school tech theatre and guess who gets to help problem solve?

When attaching smart casters to a platform to create a wagon (both legged and legless) what is the best method?

Carriage bolt from the top down so as to not see a bolt head on top? If so, how do you prevent the bolt from getting in the way of the spin of the smart caster?

Carriage bolt from the bottom up so as to not interfere with the spin of the smart caster? If so, what do you do with the part of the bolt and nut protruding from the surface of the platform?

Chewing gum? If so, bubbalicious or bubble yum? Or perhaps some juicy fruit?

TIA!

-Chris

[Van]

A technicque I've used in the past that works really well is this;
1. Attach the caster to a square of 3/4" plywood. I prefer to use an
1-1/4" Stove bolt with the head counter-sunk into the top of the plywood. Be sure to use a split washer to lock the nut in place.

2. You can now attach the wooden square to the bottom sie of the platform with Drywall screws. Again 1-1/4" work well, so you don't go all the way through the top.

The nice thing about this system is it's really fast when you needto pull things apart and/or re-attach them.

[Radman]

I'll second that, that's what I usually see done.

[CLEFFEL]

Are drywall screws are beefy enough to deal with bumps and such that I have not doubt these wagons will incur?

Thanks again

-Chris

[Van]

Aha! Good question! In this case the answer is usually yes. Since the forces at work here are shear < perpendicular to the shaft of the screw> rather than longitudinal. You could almost think of the screws as pins going into the bottom of the platform. the wieght of the platform itself is going to keep the caster from just falling off, the screws simple keep it from sliding away from where you want it placed. Now, if you were using particularly large diameter casters, so that the torque of rotational force incurred when running into an object, say a screw left on the deck or something like that, was enough that it might over come the down force of the mass of the platform, and transfer into longitudinal pull on the screw, it could become sufficient to overcome the "grip" of the screw making it necessary to use bolt through the top of the platform.

It's much easier to draw a picture of this than to explain it.
I hope I didn't confuse with that little diatribe.
Short Anwer- Yes screws are fine in most instances, unless you are planning on running the platfrom over rough surfaces really fast.

[soundman]

The way I have seen it done is to make a bunch of caster plats with bolts and 3/4" ply. The casters never leave the plate after attachement. Then the caster plates get lagged scewed into the platform. thats for the low profile option but there are more ways to skin a cat.

[Footer]

I usually do the 3/4 ply with stove bolts if possible, making a caster plate. Ya, making up caster plates sucks but after you get it done you don't have to do it again. If you build you platforming out of 1x6 (I don't like this method, but a lot of people do it) instead of 2x4 you don't even have to face the platform to hide the casters, depending on your caster size of course.

[Van]

BTW, a good rule of thumb is to; measure from the midline of the caster <swivel point> to the outside edge of the wheel. Take that distance and multiply it by 2.25 this will give you the size of the caster plate you need to cut so that when you mount the plate tight to a corner the wheel won't rub on the framing.

[gafftaper]

While I like the caster plates, if it's a one time deal and you just want to bolt them on, take your caster and wood and measure carefully how long the bolt has to be. Most casters I've seen have enough room for the bolt to hang down the thickness of the nut plus a little more no problem. Buy bolts that are the closest fit you can get. If the bolts are too long use little squares of luan as spacers to decrease the amount of bolt sticking through.

[tenor_singer]

Originally Posted by Van

Aha! Good question! In this case the answer is usually yes. Since the forces at work here are shear < perpendicular to the shaft of the screw> rather than longitudinal. You could almost think of the screws as pins going into the bottom of the platform. the wieght of the platform itself is going to keep the caster from just falling off, the screws simple keep it from sliding away from where you want it placed. Now, if you were using particularly large diameter casters, so that the torque of rotational force incurred when running into an object, say a screw left on the deck or something like that, was enough that it might over come the down force of the mass of the platform, and transfer into longitudinal pull on the screw, it could become sufficient to overcome the "grip" of the screw making it necessary to use bolt through the top of the platform.
It's much easier to draw a picture of this than to explain it.
I hope I didn't confuse with that little diatribe.
Short Anwer- Yes screws are fine in most instances, unless you are planning on running the platfrom over rough surfaces really fast.

I've had dry-wall screws shear off during a performance. I'm not sure if it was just flaw of that particular batch, but I've learned the hard way to not really trust them when used in this capacity.