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Any engineers out there? Gas spring question

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Forum topic by lateralus819 posted 11-15-2013 12:36 AM 911 views 0 times favorited 17 replies Add to Favorites Watch
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lateralus819

1409 posts in 556 days


11-15-2013 12:36 AM

Hopefully someone a lot smarter than i at this can help. I’m going to build a plane till, and instead of wasting space behind the trough for the planes, I’d like to make it hinged with extra shelves behind. The one’s I’ve seen you have to manually lift, which would be fine, but the way I’ve calculated it, would be around 80 lbs or so give or take.

I figured it’d be great to use some gas springs to assist with the lifting and to hold it in place while i get what i need.

What I’m interested in knowing is how much LBS of force per spring i’d need.

Since the planes will weigh roughly 60 lbs plus the panel they lay on another 10 or or 15.

The panel will be at a 25 degree angle. Length of panel is 26”, distance from pivot to center of gravity is roughly 10 inches.

-- Never confuse mistakes with failure. Kevin


17 replies so far

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MarkwithaK

370 posts in 1844 days


#1 posted 11-15-2013 02:08 AM

By gas spring would you be referring to a hydraulic cylinder?

-- If at first you don't succeed then maybe skydiving isn't for you.

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Loren

7625 posts in 2314 days


#2 posted 11-15-2013 02:13 AM

My comment on gas springs is they lose strength over time. I
don’t know why, perhaps degraded seals. I’d get more
than you need but of course that will make it harder to
push closed.

-- http://lawoodworking.com

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Dark_Lightning

1735 posts in 1775 days


#3 posted 11-15-2013 02:26 AM

Go down to an auto parts store and look at their supply. I have a 2000 Chevy Astro Van that has about the right weight lift gate. Check out the lengths and mounting and see if they will work. The closed length is shorter than I think you need, but that’s OK, it just means you’ll have to shorten where the things mount.

Maybe you’ll want to keep with a woodworking motif and put counterbalance weights like a window sash instead of having high-tech pressurized gas cylinders on a wooden tool box. Plus, you could adjust the weight for a nice lid raising.

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Gman024

2 posts in 1023 days


#4 posted 11-15-2013 02:38 AM

Check out the McMaster.com web site and search for gas struts. They provide information on sizing the struts for the load being lifted.

-- Glenn ~ Grafton, New Hampshire

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cutmantom

283 posts in 1701 days


#5 posted 11-15-2013 02:38 AM

The counter weight sounds best to me, easy to fine tune and you don’t have to worry about a part that might be hard to find when it comes time to replace

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lateralus819

1409 posts in 556 days


#6 posted 11-15-2013 02:52 AM

Nothing high tech about it. I just saw they actually make them for furniture.

I’m not worried about them breaking down. I know they break down over time, but that’s years down the road. What is this “counter balance” you’re speaking of? Link to an explanation, I’m familiar with windows that use it, but how would i incorporate it into a plane till?
Thanks for the suggestions though i appreciate it.

-- Never confuse mistakes with failure. Kevin

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Grandpa

3158 posts in 1342 days


#7 posted 11-15-2013 02:58 AM

Show us a sketch of your plane till.

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lateralus819

1409 posts in 556 days


#8 posted 11-15-2013 03:00 AM

I will in 1 second, just about finished.

-- Never confuse mistakes with failure. Kevin

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lateralus819

1409 posts in 556 days


#9 posted 11-15-2013 03:12 AM

-- Never confuse mistakes with failure. Kevin

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lateralus819

1409 posts in 556 days


#10 posted 11-15-2013 03:13 AM

Basically I’d like it to open about flat with the top, so the planes don’t fall off obviously.

-- Never confuse mistakes with failure. Kevin

View dawsonbob's profile

dawsonbob

381 posts in 422 days


#11 posted 11-15-2013 04:08 AM

You might want to check out Rockler. I’m pretty certain they carry an assortment of gas struts for furniture.

-- Mistakes are what pave the road to perfection

View MrRon's profile

MrRon

2848 posts in 1910 days


#12 posted 11-15-2013 10:07 PM

The gas strut must be great enough to keep the lid open, so if the lid + the planes weigh 80#, then the strut must be able to counter 80#. Too small, and the lid will not stay in the open position without some sort of latch. If the strut is too large, the lid will want to open by itself unless a latch is used to hold it in the closed position. At any rate, you will need a latch someware.

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joeyinsouthaustin

1257 posts in 739 days


#13 posted 11-15-2013 11:48 PM

We use these for that application. The one pictured isn’t the heavy duty, but the heavy duty can hold a lot. they can also be set to self open the lid. The tension is adjustable as well to set for multiple weights, and eliminates the sag that will happen over time with gas struts. You would need two. We get them at heafele.

-- Who is John Galt?

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joeyinsouthaustin

1257 posts in 739 days


#14 posted 11-15-2013 11:50 PM

Here is a pic of the heavy duty in operation. google maxi lid stay for heavy doors

-- Who is John Galt?

View patcollins's profile

patcollins

997 posts in 1531 days


#15 posted 11-15-2013 11:55 PM

The angle from the strut to the door is pretty shallow and thus alot of the force of your spring gets wasted. Im going to say the angle fully open is 15 degrees.

Lets also say the force your gas cylinder provides is 100 lbs, at an angle of 15 degrees the force holding the lid open is

force = 100 lbs * sine (15 degrees) or 25.8 lbs is all this cylinder can exert on the lid keeping it open. Now as the angle changes so does the force exerted on the lid.

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