locking unidirectional casters - design help

I have a need at work. I need to move a text fixture around on a concrete floor which isn't flat, and then lock it in place. I can't use a traditional caster because the initial swivel moves in too coarse of a way for me to accurately position the fixture. I need to be able to locate and rotate the fixture within say 1/4". I tried one of these https://www.omnitrack.com/wheels-castors/omnicasters/ but it is cheap in construction, the brakes are hard to use in situ and appear fragile, and also lift the fixture a bit. The balls don't even rotate particularly well. I like an omniwheel but there isn't a way to lock them. I don't have enough height to use any floor brakes.

Is there a better option?

Maybe these?  https://www.grizzly.com/products/grizzly-400-lb.-capacity-workbench-caster-set-4-pc./t32334?gad_source=1&gclid=CjwKCAiAq4KuBhA6EiwArMAw1M-9yBI_TJaFGMEPO8xJO1Sh2N6zblT0tw9_T4ds0HVlkbh_RaIgUxoCRTwQAvD_BwE

I need almost no -caster- on the casters. I have very little room to pivot and I can't necessarily deal with the circle dance that the pivot takes when you start it moving a new direction.

Also, specifically I need that form factor, a threaded stud of some flavor.

Or if you need something more elegant, perhaps these: https://afx.bz/airpux-2/

Gotcha.  I'll keep looking

Just throwing some things out there.  No brakes on this one, but they might have some, or you could engineer a brake

Curtis73 (Forum Supporter) said:

Just throwing some things out there.  No brakes on this one, but they might have some, or you could engineer a brake

Yeah these things are everywhere. Putting some form of brake into/onto one is a decent thing. I am thinking of a tiny floor lock I can mount alongside or a shroud which can mount over the top, but I am trying to avoid customization too much. I guess I could just engineer the whole thing myself.

This could work, and it's from the same place. I was initially thinking of using one of these in the center and some legs where I tried the omnicasters with springs. I think this thing has a brake though. Maybe I can just use four.

https://www.omnitrack.com/wheels-castors/ball-tables-rails-skates/ball-transfer-skates-accessories/

I don't know how elegant this needs to be, but a brake can be as easy as a chunk of 2x4 cut at a 45 and a door hinge.  That's how I make stage brakes for theater wagons.  You could dress it up by making it out of aluminum or something prettier.  What I do is hinge a piece of 2x4 to the edge of a wagon but first, I roll the caster up onto a scrap of luan.  When you step on the 2x4, it over-centers and lifts a couple mm.  You're then resting on the 2x4.  To move it, just flip up the 2x4.  I use a piece of velcro or a magnet to hold it up in transport.

Curtis73 (Forum Supporter) said:

I don't know how elegant this needs to be, but a brake can be as easy as a chunk of 2x4 cut at a 45 and a door hinge.  That's how I make stage brakes for theater wagons.  You could dress it up by making it out of aluminum or something prettier.  What I do is hinge a piece of 2x4 to the edge of a wagon but first, I roll the caster up onto a scrap of luan.  When you step on the 2x4, it over-centers and lifts a couple mm.  You're then resting on the 2x4.  To move it, just flip up the 2x4.  I use a piece of velcro or a magnet to hold it up in transport.

 

 

That's a good idea for a concept. Let me play with that a bit. I have money I can spend, so even a rubber wheel chock would work there.

If you wind up going with something like the universal ball caster, then you might flip the brake idea upside down (literally) and lift a locking ring into the ball, instead of pushing the braking mechanism into the floor/wheel. A hinged lock ring with an over-center actuation  opposite the hinge could put a fair braking load on a ball bearing type of caster. Note that ball bearing casters do not like rough surfaces. If you get the geometry right or use a pull cable you could lock multiple casters at one time/simultaneously.

https://www.mcmaster.com/products/leveling-casters/mount-type~stem/

when its (equipment) in place, you wind down the center rubber feet. that work?

I would separate the functions. Look for a set of good casters for the motion and use some pins to locate the fixture to some holes in the floor. If it's moved often, then you might want some steel plates in the floor for the pins to engage. 

How big is this item? Would a Pallet Jack or a Fork Truck work best? Just have adjustable legs to level it when put in place. 

tester (Forum Supporter) said:

I would separate the functions. Look for a set of good casters for the motion and use some pins to locate the fixture to some holes in the floor. If it's moved often, then you might want some steel plates in the floor for the pins to engage. 

The whole point of this is to move it around a lot on a nonlevel floor and lock in in place against a fair bit of force. I am going to try the rubber plunger door stopper style floor locks though, because that premise is sound.

MyMiatas said:

How big is this item? Would a Pallet Jack or a Fork Truck work best? Just have adjustable legs to level it when put in place. 

 

 

 

I started with a transmission jack. We won't have room to operate a pallet jack sadly.

ralleah said:

https://www.mcmaster.com/products/leveling-casters/mount-type~stem/

 

 

when its (equipment) in place, you wind down the center rubber feet. that work?

I need those switched, that is, I need the caster wheel to have nearly no caster. With the horizontal distance on those, the center point swivels about its radius, making fine adjuastments difficult.

stafford1500 said:

If you wind up going with something like the universal ball caster, then you might flip the brake idea upside down (literally) and lift a locking ring into the ball, instead of pushing the braking mechanism into the floor/wheel. A hinged lock ring with an over-center actuation  opposite the hinge could put a fair braking load on a ball bearing type of caster. Note that ball bearing casters do not like rough surfaces. If you get the geometry right or use a pull cable you could lock multiple casters at one time/simultaneously.

If I have enough ball panetration, and therefore enough ball diameter, I may try this. A ring of brake material pulled up against the ball is intriguing.

Here ya go! Castors with brakes and locking swivels.

https://www.grainger.com/product/41GT62?gucid=N:N:PS:Paid:GGL:CSM-2295:4P7A1P:20501231&gad_source=1&gclid=EAIaIQobChMI47LzpvuWhAMVHNXCBB2eiAIwEAQYAyABEgJwj_D_BwE&gclsrc=aw.ds

MyMiatas said:

Here ya go! Castors with brakes and locking swivels.

https://www.grainger.com/product/41GT62?gucid=N:N:PS:Paid:GGL:CSM-2295:4P7A1P:20501231&gad_source=1&gclid=EAIaIQobChMI47LzpvuWhAMVHNXCBB2eiAIwEAQYAyABEgJwj_D_BwE&gclsrc=aw.ds

 

Yeah I have two flavors of essentially that exact thing. The caster radius is too large, so you need to pivot about the rotational axis of the swivel to move the fixture, and that's too coarse of an adjustment to be handy.

Curtis73 (Forum Supporter) said:

Or if you need something more elegant, perhaps these: https://afx.bz/airpux-2/

The same company I tried offers a ball transfer with a pheumatic extender, so you release air pressure and the ball disappears and sets the thing down. It's neat, but I don't want to adjust the height that much, and I don't have a ready air supply.

Curtis73 (Forum Supporter) said:

Just throwing some things out there.  No brakes on this one, but they might have some, or you could engineer a brake

Do you have access to a drill press and a tap and die set?  If so, drill that on the side and thread it with a 1/4-20 bolt as a lock.  If the housing is thin slightly over size the hole and tack a nut on the outside.  Gentle pressure against the ball should lock it for your purposes.

11GTCS said:

Curtis73 (Forum Supporter) said:

Just throwing some things out there.  No brakes on this one, but they might have some, or you could engineer a brake

Do you have access to a drill press and a tap and die set?  If so, drill that on the side and thread it with a 1/4-20 bolt as a lock.  If the housing is thin slightly over size the hole and tack a nut on the outside.  Gentle pressure against the ball should lock it for your purposes.

I've considered it, but... I don't love it. Hard to deal with in the field, can't make sure not to let the balls out or ruin the races without a drawing, can't disassemble them to remove chips.

I think just a plain ball transfer unit and then a way to quickly pull it up, similar to the air setup earlier, so the jack sits on the chassis.

tuna55 said:

ralleah said:

https://www.mcmaster.com/products/leveling-casters/mount-type~stem/

 

 

when its (equipment) in place, you wind down the center rubber feet. that work?

I need those switched, that is, I need the caster wheel to have nearly no caster. With the horizontal distance on those, the center point swivels about its radius, making fine adjuastments difficult.

I'm speaking from experience in using these in my basement shop for a tablesaw cart. The floor is annoyingly (sloppily) unlevel tiles. Use that perspective for what you will, but I had a hard time finding a better solution. I'm curious where this thread ends up.

I have some ideas gleaned from what I heard here, what I have in my office, and a nearly unlimited McMaster-Carr budget. Stay tuned.