Dolly base and wheels

[Terry Lee]

Hey everyone,

Which would you prefer out of these two designs? I'm talking in terms of the wheel's capability to withstand alot of weight. It seams that the comon design is the angle iron with 4 wheels on each. The other design I found on the internet looks like It would withstand alot of weight, but would not be as stable...I dunno, any suggestions?

[Chris Soucy]

I suppose my immediate question having looked at both examples is "how much is "a lot of weight"?

Both the dolly's you show have two joints on that moveable arm, with the actual weight being applied well away from the point of contact of the wheels to the track.

This means that the moveable arms ability to resist a load is purely dependant on the strength of those moveable joints - the spyder in particular doesn't look all that robust.

My jib, with all attachments on board, Canon XH A1, counterweights and tripod, weighs in about 100 lbs. 3 attachment points for tripod, say 33 lbs per leg.

Would I apply 33 lbs to the spyder with those dinky little joints and that arm extended - nope. The other one? Maybe, but wouldn't stake my life on it.

I use a B. Hague dolly which has a different arrangement - an "H" frame with a set of wheels at each end of the long sections of the "H" (4 sets of wheels).

The tripod attachments are: 1 towards each end of one long section of the "H", the third on the "H" cross bar, furthest from that long section. The other long section of the "H" is free to pivot about it's joint with the cross bar to smooth the ride.

The three bars of the "H" are thick wall rectangular box section aluminium, you can stand on the unit and even jump up and down on it and it will not bend/ break (I weigh 180 lbs). Wouldn't do that to either of the units you posted.

(Wouldn't have done it to mine except I needed to "destruct test" it for all known contingencies).

CS

[Terry Lee]

Chris, I had an idea constructed in my mind and it didn't come out right when I typed my inquiry...sorry for the confusion.

What I meant was, if put the angle iron design on a flat platform dolly with plywood using the common method - angle iron and 4 wheels - would a lot of pressure force the wheels down onto the pvc pipe forcing them to spread and unable to move freely? I ask because I saw a dolly once with this design that when it rolled the wheels would squeak real bad like it had to much weight on it. When I saw the other design I posted with the two wheels positioned on top of the track/pvc I thought this was an innovation or solution to the weight capacity problem with the previous design. I may be wrong...the squeaking may be from bad bearings, but I wanted to double check.

Thanks Chris for your reply.
-Terry.

[Chris Soucy]

Think I followed your post, but "think" isn't really clear enough........

The basic problem with the wheels at any angle other than in line with the load is the bearings.

Angled wheels certainly aid in tracking, but put a huge load on the bearings, which, if not designed accordingly, will fail in very short order.

The noise you describe may well have been just that sceaniro playing out.

The design where the main downward thrust is taken by a set of wheels in line to the load, with just an ancillary set angled to deal with guidance, is the way to go.

If you can arrange such a configuration, you're good to go.

If not, well, unless the wheels are designed for such a load, they will fail in very short order.

Don't know if this has helped, but hope so.


CS

[Terry Lee]

Originally Posted by Chris Soucy

The design where the main downward thrust is taken by a set of wheels in line to the load, with just an ancillary set angled to deal with guidance, is the way to go.

Chris,

Yes, this confirms my theory. As you say here, I will need a set of wheels that will accommodate for the downward thrust of weight. The design I posted with the 6 wheel configuration seams to fit your description.

-Terry.

[Onno Perdijk]

Hello all,

With the payloads we are using I would not worry about the wheels or the bearings. The bolts and carbon-steel (instead of stainless-steel) will be more of a problem... Years ago I had bended axes after a payload of 800 kg on 8 wheels only... that was scary!

The design with two wheels on top and 4 guiding wheels seems to be the best design, however it asks its utmost of the perfectness of the track and its joints;
- you will feel every unsmoothness of your track on 3 sides (left-right-top)
- Your track needs to be exact the diameter of the gauge you have made your wheelset or it will not fit or it will create a freeplay.

The V-grooved design allows you to use pipe-diameters from say 30mm till 60 mm which gives you more versatility in using available equipment. It only touches the wheel on two sides of the track.

Another issue when using scateboardwheels is its softness/hardness grade...


Good Luck,

Onno Perdijk