Help me with a rough design?

[FigureItOut]

I've been wanting to build a platform for working under dash similar to, but better than the ones pictured. I have a couple general ideas in mind, but the one I prefer, I have some doubts about and I wanted to get opinions as to whether it could be built stiff enough, and still compact.

Picture a platform like above, only instead of the cross piece resting on the ground, there's four swivel casters. The whole thing ends up shaped like a tall "U", on it's side, such that you can roll into position and adjust, while remaining in the same position on the platform.

The bottom shouldn't have any problem sliding under the car, so the footprint can be the same or even larger than the platform, for stability. The platform height must be adjustable obviously. My biggest concern is that there's no way it's going to be stiff enough to hold me up, and hold the platform up off the car's threshold.

Alternatively, I can do it almost just like the ones pictured, only with two swivel casters at the bottom support, and one swivel caster mounted basically directly under my head.

Any thoughts on my general ideas, or other ways to do this that come to mind?

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[FigureItOut]

Oh and please let me know if my description isn't clear enough to make a mental picture. It's difficult to tell, since I can see it perfectly, if the words will translate to the mental image I'm trying to convey.

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[larry_g]

Use one like you picture where the frame is stable and have the top surface slide on the framework. The framework at the car could have a horseshoe that slips over the threshhold to keep it stable.

If you had one on casters as you said would you want swivel casters at both ends or one end fixed to keep it rolling basically straight? Basically cut the box top off a shopping cart and use the floor of the box and chassis.

lg
no neat sig line

 

[kerrynzl]

modify a weightlifting decline bench an add casters to it.


Or if you're a "real man" steal your wife's ironing board and modify this! [please let us know how this pans out]

 

[bdelmar2]

Not sure how well something like that would sell.

I will say your idea sounds better than the one pictured.

Basic problem is that there isn't enough room under the dash already, at least for me. Trying to get a creeper in there as well just doesn't seem practical.

 

[Mike W.]

How long is the bench above? How much does it need to support, a large man I'm guessing? Let me know and I think i can tell ya what kind of and shape of material would support you without failing or bending to the point of hitting the threshold. I'm a designer and have software that can analyze what you're talking about pretty quickly and easily.

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[FigureItOut]

Use one like you picture where the frame is stable and have the top surface slide on the framework. The framework at the car could have a horseshoe that slips over the threshhold to keep it stable.

I think this is a better plan than what I'd had in mind. Probably simpler to build well.

modify a weightlifting decline bench an add casters to it.


Or if you're a "real man" steal your wife's ironing board and modify this! [please let us know how this pans out]

I thought of an ironing board actually. A weight bench is a good thought also, it'll already be built pretty sturdy, and be padded. If I get it built, I'll absolutely post the process and result.

Not sure how well something like that would sell.

It's for me, and my back and neck have already sold me on it, ha ha.

How long is the bench above? How much does it need to support, a large man I'm guessing? Let me know and I think i can tell ya what kind of and shape of material would support you without failing or bending to the point of hitting the threshold. I'm a designer and have software that can analyze what you're talking about pretty quickly and easily.

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Very kind of you to take the time and resource. I'm really interested in the result. I'm 5'8", about 180. I think about 4' long would let me bend at the knees, and have a inch or so to spare at the top. I want to make it as narrow as possible and still be comfortable, to give the best chance of being effective in tight vehicles.

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[drivesitfar]

FIO: i was thinking weight bench too and saw the Kerry mentioned it. there are some benches that attach to a rack that don't have a leg on one side or that come with legs that can be removed so you can set it up at car floor's height on one end and floor on the other. also built pretty sturdy in most cases.

i'd say inventing a wiring system that you could pull out to work on for starters. i never have liked going in that area and it's hard to get my 6'3" frame down to 100 pounds to fit too.

 

[dontlifttoshift]

Not sure how well something like that would sell.

I will say your idea sounds better than the one pictured.

Basic problem is that there isn't enough room under the dash already, at least for me. Trying to get a creeper in there as well just doesn't seem practical.

This is the reason the device pictured works better than the device proposed. It allows the bench to decline into the footwell giving you better positioning under the dash.

 

[BLUE72CAMARO]

Google topside creeper and you can see how some similar devices made to work at much higher elevations are made using the same principle your looking at.

 

[Mike W.]

I think this is a better plan than what I'd had in mind. Probably simpler to build well.

I thought of an ironing board actually. A weight bench is a good thought also, it'll already be built pretty sturdy, and be padded. If I get it built, I'll absolutely post the process and result.





It's for me, and my back and neck have already sold me on it, ha ha.

Very kind of you to take the time and resource. I'm really interested in the result. I'm 5'8", about 180. I think about 4' long would let me bend at the knees, and have a inch or so to spare at the top. I want to make it as narrow as possible and still be comfortable, to give the best chance of being effective in tight vehicles.

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Not a problem, I get a kick out of figuring stuff like this out.

What you see below/attached is a "C" shaped part because to me the biggest problem with this is getting something small and relatively thin (and cheap lol) to fit where you want and hold your weight and not bend too far. I didn't add height adjustment because I don't think it will effect this analysis. Our C part is made of 1" square tube and some 3/4 x 1/4 flat stock, all pretty cheap stuff. There is a brace 12" in but I don't think it'll effect your ability to get farther in the car.

With your 180lbs on TWO of our C shaped parts it should only bend less than 3/16" at the very end. I don't think it'll go that far, prolly more like an 1/8". This pic is a gradient so the blue is the least (none) and red is the most displacement (3/16").

As far as it actually failing and dumping you on the floor it would take many times your weight or poorly welded

Also this is shape/look is just to simplify the digital/FEA test. It could be changed to look cooler lol

I also included a drawing to show the actually material size and length.

Let me know if you want to flesh out something you'd want to build I don't mind helping.

Mike

 

[FigureItOut]

Not a problem, I get a kick out of figuring stuff like this out.


Mike

Wow thanks a lot Mike. This at least tells me how built up this thing will have to be. Looks like some pretty cool software.

I've got a few changes to think through based on some of the ideas so far, I'll definitely update once I settle on something.

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[rsanter]

a steel frame will easily hold your weight.

making one for youself will be easy. just go thicker on the material that holds you up and put several catilever beams that are thin for clearance
for something that you are going to make and sell that's going to be a problem. the weight and expense in materials going to hurt sales.

so for yourself build it.
as an idea for sale....don't think so

bob

 

[myronw]

Hi Guys,

I've got an old incline sit-up board that would work great for that! Thanks for the idea.

Myron

 

[smschriefer]

I just take the seat out and lay down on the floor. That's the only way I work under the dash of my Miata.

 

[jd_1138]

I just take the seat out and lay down on the floor. That's the only way I work under the dash of my Miata.

Yep, the seat is in the way. I'd remove it.

 

[FigureItOut]

This is intended for multiple cars daily, paid by the job. Many, perhaps most, can be completed without getting on my back, honestly, but the design and build here are as important to me as the result.

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[jd_1138]

This is intended for multiple cars daily, paid by the job. Many, perhaps most, can be completed without getting on my back, honestly, but the design and build here are as important to me as the result.

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Oh ok. I'd have the legs to be totally adjustable -- remove a pin and slide the legs up and down and put the pin back in. If the 2 legs are adjustable, you can use it for all vehicles.

Just use some tubes for the 2 legs and drill holes in them for the cotter pin to go into. One tube would be larger and slide over the tube that's a little smaller in diameter.

Could just use plywood and cut it to a nice compact shape and put some foam on top and wrap it in vinyl.

 

[FigureItOut]

Oh ok. I'd have the legs to be totally adjustable -- remove a pin and slide the legs up and down and put the pin back in. If the 2 legs are adjustable, you can use it for all vehicles.

Yup, that's the idea. At this point I'm thinking really along the lines of having a well padded support to go over the threshold.

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[owenst7]

Most of my work is inside 4x4 pickups, and the space issue is still an issue for me (and I'm a skinny guy too). I do think something more like a stool would be great though. Usually I plant my feet flat on the ground and place most of my weight on my shoulder blades/spine on the floorboard. I think it'd be great to have a stool or something adjacent to the door that I could place under my lower back and/or pelvis. Bonus would be if it had casters so I could sit on it and roll in to position, but it would need to lock easily or something so it didn't roll out from under me when I laid down. I've seen some office stools with spring loaded casters that retract when you step on the stool. Something that worked along those lines but allowed some movement would be nice...maybe if it had a small back rest that retracted the casters when it folded down.

 

[Brian_WK]

Not a problem, I get a kick out of figuring stuff like this out.

What you see below/attached is a "C" shaped part because to me the biggest problem with this is getting something small and relatively thin (and cheap lol) to fit where you want and hold your weight and not bend too far. I didn't add height adjustment because I don't think it will effect this analysis. Our C part is made of 1" square tube and some 3/4 x 1/4 flat stock, all pretty cheap stuff. There is a brace 12" in but I don't think it'll effect your ability to get farther in the car.

With your 180lbs on TWO of our C shaped parts it should only bend less than 3/16" at the very end. I don't think it'll go that far, prolly more like an 1/8". This pic is a gradient so the blue is the least (none) and red is the most displacement (3/16").

As far as it actually failing and dumping you on the floor it would take many times your weight or poorly welded

Also this is shape/look is just to simplify the digital/FEA test. It could be changed to look cooler lol

I also included a drawing to show the actually material size and length.

Let me know if you want to flesh out something you'd want to build I don't mind helping.

Mike

What if you put one of those chair air/spring shocks like on office chairs on the tube on the right of the picture and a hinge on the top left. It would give you a more infinite adjustment and allow you to adjust the angle and incline of the "back rest" while laying on it. Also don't forget about some sort of head and neck support that is adjustable.

Brian

 

[FigureItOut]

What if you put one of those chair air/spring shocks like on office chairs on the tube on the right of the picture and a hinge on the top left. It would give you a more infinite adjustment and allow you to adjust the angle and incline of the "back rest" while laying on it. Also don't forget about some sort of head and neck support that is adjustable.

Brian

Yup, I've got the shock in my plan already, not quite how you described it though. I had one in my spare parts stockpile.

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[Keyblazer]

Great idea.
Couple of thoughts...
You might want to pad the underside of the thing to protect customers threshold plates.
Add a bar to the outside legs to hook your ankles around to make sitting back up easier.

 

[Kevin54]

If you are going to be designing and making something from scratch, whay not make a dual purpose chair/bench that you could use as a chair when working along the sides of a vehicle.....Have it as a chair when doing brakes, working on rocker panels, and so on. Then when you need to work under the dash, release a mechanism that would let the back drop down into a horizontal position and be able to roll up to and over the sill of the door.

You could always use something like the bottom of a office chair that raises and lowers the chair by the hydraulic shock. In fact, I don't know if an office chair wouldn't work if you could hinge the back somehow. Some chairs have a wide steel strap that holds the back in place. Possibly modify that, along with incorporating a spring loaded pin that would lock the back in an upright position, or lock it in a horizontal position. The only thing I don't know would be if the wheels of the chair would remain on the ground when the back is reclined to the horizontal position, or if it would want to tip backwards.

 

[gahrajmahal]

The hydraulic shock came into my head at first too, but the reality is you will want to bump up or down once laying on your back. I'd change to a 12 volt linear actuator, cordless battery powered to do the fine adjustments. The pin idea is good for coarse initial height adjustment.
I used to be a radiation therapist and the treatment couch is cantilevered, made from carbon fiber to minimize radiation scatter and is extremenly strong with a 450 lb load limit. It is also very flat and uncomfortable. I would look into a fiberglass frame to build in some contours to match your back or possibly that Aero office chair stretchy mesh for the back support. The part under your **** should be more solid and chair like.
We want to see photos of your prototype when it is ready!

 

[FigureItOut]

Taking some of the ideas I've gathered I have a general idea in mind. For a frame I think I'll use round tube in a big rectangle with rounded ends. I've got buddy with a bender, but the basic shape is not dissimilar to the frame of a hand truck so I may find a cheap one to pilfer. 4-5 flat bars as cross pieces with a nice thick pad, and flush mounted LED lights in a half circle around the top.

The frame would have a hydraulic shock at the foot end with a couple casters, then the whole thing will rest on a padded u-shaped support that goes over the threshold. The support itself, I haven't quite figured it out. It should have slots for the tube to rest in, allowing it to slide in and out, pivot up and up down, and pivot horizontally.

I played with some casters with the wheel removed, they make a nice little channel that tube would slide through and allow pivoting. If I move the axle closer to the swivel part, the sides would keep the tube in the channel. The only issue is that when I tried it, tube doesn't want to roll over the axle, it just slides with a horrible screech.

I'm gonna go a to a specialty bearing supply place sometime this week, and see if there's anything that catches my eye.

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[speed bump]

I would just buy or build the one pictured. To make the platform stiff enough and free floating will take up a lot of room you don't have and will make it uncomfortable (remember your shoulder blades will typically be hanging off of this). On casters you will move it around with your body while trying to reach for something (even if they are locked, I do it regularly on my topside creeper).

 

[lakeroadster]

While I applaud your enthusiasm I can't envision this being something that would work.

Every vehicle I have ever worked on space was tight trying to work under the dash when I was simply laying on the floorboard of the vehicle.. let alone elevated above it.

And I'm a fairly thin guy.

 

[FigureItOut]

While I applaud your enthusiasm I can't envision this being something that would work.

Every vehicle I have ever worked on space was tight trying to work under the dash when I was simply laying on the floorboard of the vehicle.. let alone elevated above it.

And I'm a fairly thin guy.

Yeah, the more I think this through, and especially thinking about it while I'm actually working, the more I just think I'm scrapping this one. Even if it works, it has limited utility, most vehicles don't require that level of access for any significant time.

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