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Articulated arm for magnifying glass, camera, microscope?

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PekkaNF:
The simple parallel linkage has no design challenges unlike those "stedi cam" contraptions.
http://tom11.com/blog/?cat=4

Much on those design seem to revolve around basic parallel arm linkage designs.

Basically my desgin problem now very mundae: Finding the gas strut that is small enough in size and capacity. If the gas strut is too strong, something like 400N then the linkage ratio comes large....not ideal. If the gas strut is too large I have to mount it outside, making it bulky or if I reduce other parts, then bearing points are further together and that means more accuracy is needed and pin load is higher. All more engineering and manufacuting challenge. I'll get one more bar of thin walled pipe and try out another arrangement.

Pekka

BillTodd:
Pekka,

Why not make one end of the gas-ram mount adjustable ?  If it pivoted at the fixed end somewhere between the two arms it would reduce the force at the end of the arm . Perhaps a U section gas-ram pivot could be made to slide inside the fixed vertical part?

If the top arm was a an inverted U section the gas-ram would fit inside as it folded.

PekkaNF:

--- Quote from: BillTodd on March 26, 2016, 12:39:30 PM ---Pekka,

Why not make one end of the gas-ram mount adjustable ? ,,,,,

If the top arm was a an inverted U section the gas-ram would fit inside as it folded.

--- End quote ---

Haa, Very much the idea I have been playing with...I placed some parts on underarm, but effectively the same thing.

And even more of a coincidence I got a U-trough cable quard for upper arm, I was going to use it with matching 25 mm square pipe, but run into a little snag - the smaller gas strut (150N), is fairly perfect to float the 970g lamp, but with only with a narrow margin. Could change the lever ratio thoug.

Pekka

Jonny:
Welcome to the club Peka that sort of thing drove me round the bend last year for an entirely different product that needed one touch solid lockup.
Bolts and screws through the arms will wear, bare in mind detectable play means a lot at other end.

One thing noticed looks like only have around 30 degrees movement either way in one plane, increase the pivot centres so can get a full 90 degrees swing and a lot more movement.
Have had some bearings last two months for a mark 4 1/2 design.

Never took any of these apart, have two quality English ones would this style offer better service with clamping nut acting as friction either via bellevilles or compression spring.
http://www.chronos.ltd.uk/acatalog/111940l.jpg

PekkaNF:
Thank you for stedicam link. They are interesting. I'm not too interested the arm/gimbal/mass system. But iso-elastic arm systems are interestin, because, much of them are parallel linkage types, some have spring/pulley system to keep spring on constant force area.

For me minimizing friction and maximizing constant force is not very relevant. Constant force is nice, some friction desirable.

This is nice design and some design features are interesting:
http://entertainment.howstuffworks.com/steadicam2.htm

Pekka

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