Software Support > Automated Projects

Increasing travel of a moving axis?

(1/3) > >>

Cretster:
Hi guys

I started a thread a while back about wanting to replace my current upright scratch built cabinet with a new one that can convert from stand up cab to sit down racer type.

I've got lots of ideas on how to do different aspects of this (t'll be a bit of a ballache in general), but one thing I need to figure out is the most suitable means of increasing the amount of travel I get from say an electric ram device, in order that it can be contained in the cabinet still.

The main cause of needing this, is for the lower half of the cabinet where the seat needs to extend out from.  I have one electric ram capable of 160kg lift, that has about 13" travel and this will be used to raise & lower the monitor module, so if I have a similar one for the seat, thats not going to be nearly enough distance for the seat to move out & away from the cabinet to give a good layout.

So am thinking of ways to translate movement into larger movement to facilitate this. 
1) I could have a big arm/lever with a pivoting at one end and the ram moving it just above the pivot point.  Would give a lot of travel but I don't think it's suitable as it could use a lot of space etc.
2) A scissor 'trellis' type mechanism.  The ram would push together the two end pieces, which extends the scissor mechanism outwards.  Might be able to get enough travel doing this and keep it compact inside the cab, but often these sort of mechanisms suffer wobbliness and so on. 
3) Something telescopic. Something like a bottle jack but with more travel, and able to be motorised would be idea. 

I haven't measured all this out, yet and am not sure what the norm would tend to be for a driver layout.  I think I need to set up a seat, 'assume the position' then measure what's what.

I hope you'll excuse the crap quality sketch here but this is the basic idea of what I'm on about more or less.  The wheel I have on my existing cab works in a similiar way to this, in that it swings down out of the way inside the cabinet, behind the front door panel when not in use.



But mostly at this stage, I'm just trying to figure the best way to get that outward travel of the seat without costing an absolute fortune.  Was thinking something like heavy duty drawer runners would help at the sides and would help for including some side wall type panels.

Thanks for any useful suggestions on the mechanics of this part guys - you all seem pretty good at this side of things!

Cretster:
This sort of thing for the sides i suspect.
I could fit a pair this size in, but am sure it would need more than 60cm of travel for the seat. Possibly double, but it might be possible to combine a couple of these together to achieve that?

http://pages.ebay.com/link/?nav=item.view&alt=web&id=330695818115

DaOld Man:
Looks like a pretty complex project.
For the seat, I would go with a rack and pinion setup.
You could have the rack turned sideways then a geared motor (wind shield wiper) with the pinion gear to push the chair out and pull it back in.

Here is a motor that would probably be easy to adapt to a rack and pinion setup. (Im not saying that this will work, its just a suggestion).

http://www.allelectronics.com/make-a-store/item/dcm-467/12-vdc-60-rpm-window-motor/1.html

Of course with this system, the rack is probably going to come out the back of the cabinet when the chair is retracted.
Maybe you could have a motor attached to a wheel under the seat that would pull it out and push it back in?
You would still need bars to guide the seat though.
Think about safety on this project, I can see several possible pinch points that could catch a curious finger or hand.
You may need some type of switch to detect anything in the way at the pinch points. (They make safety tape that is used for this purpose on industrial machines.)

Cretster:
Thanks mate, yes it'll be complex but I think pretty cool if I manage it.

Pinion\rack would be ideal but as you say would need to extend out back of the cab, and it has to sit against the wall due to space constraints (hence just not building a full on driver cab in the first place).

Motorized wheel beneath the seat is interesting though. I could have end switches to limit the travel, or program distance to move with an arduino and stepper motor etc.

Yes, there'd need to be some sort of safety functions too.

I've mostly got the rest sussed out in theory so I'll have to maybe build a mockup. To check how it needs to fit together.

PL1:
Have you considered a 2:1 pulley configuration?

It doubles the speed, but only allows you to lift half as much.




Scott

Navigation

[0] Message Index

[#] Next page