Hatch Gas Spring/Strut Calculator

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Re: Hatch Gas Spring/Strut Calculator

Postby Gunguy05 » Sat Apr 18, 2015 4:19 pm

Awesome, awesome!

Thank you! After tugging on my 93 lb (at the midpoint) hatch.. THIS worked like a boss! 8) :D

I had to "fudge" things a bit as the calculation for a 56.5 in hatch, 93 lb, gave me that I needed 33.9 in struts, 133 lb, The longest struts I could find were 30.9in, and 150 lb. So.. I figured a little shorter, a little more force might work well, and it did. I still have to put the luan on the inside of the hatch, but that should be in the 6-10lb range, and I have to give a good tug on it now to get it down. Definitly feel stable and safe above my head.

BTW: A great source on ebay for longer struts and brackets is http://www.ebay.com/usr/strut-your-stuf ... 7675.l2559

The spring I used, http://www.ebay.com/itm/371303887887?_t ... EBIDX%3AIT

The brackets,
Hatch : http://www.ebay.com/itm/391109960046?_t ... EBIDX%3AIT
Galley wall: http://www.ebay.com/itm/391035825660?_t ... EBIDX%3AIT

I will try and post a short video/photo set later. They were much easier to install than I had thought they would be. :thumbsup:
Brian


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Re: Hatch Gas Spring/Strut Calculator

Postby danlott » Sat Apr 18, 2015 9:56 pm

I am glad the calculator worked for you. 150 lb struts are a little more than you needed, but you still have to add the inside plywood and whatever else you end up putting on the inside of your hatch. Sounds like it should work well. Thank you for the feedback.

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Re: Hatch Gas Spring/Strut Calculator

Postby DougN » Tue Jun 09, 2015 11:45 am

Hi Dan, thank you for making this calculator! Question, if I reverse the mount points so the outer mount point is on the hatch and the inner mount point in the galley, will the calculations be the same? Any reason not to do it that way? I read somewhere it makes the hatch more stable, especially in wind.

Thanks,
Doug
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Re: Hatch Gas Spring/Strut Calculator

Postby dales133 » Tue Jun 09, 2015 5:38 pm

Hey Dan could you please check that link it seems to have died
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Re: Hatch Gas Spring/Strut Calculator

Postby danlott » Sat Jun 13, 2015 7:44 pm

dales133 wrote:Hey Dan could you please check that link it seems to have died


The file attachment is still there and works. Not sure why you are not able to download it. If you PM me your email address I will send it to you.

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Re: Hatch Gas Spring/Strut Calculator

Postby dales133 » Sat Jun 13, 2015 7:50 pm

Thanks I'll try it again first
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Re: Hatch Gas Spring/Strut Calculator

Postby danlott » Sat Jun 13, 2015 7:56 pm

DougN wrote:Hi Dan, thank you for making this calculator! Question, if I reverse the mount points so the outer mount point is on the hatch and the inner mount point in the galley, will the calculations be the same? Any reason not to do it that way? I read somewhere it makes the hatch more stable, especially in wind.

Thanks,
Doug


There are lots of ways to mount the struts and your idea would certainly work. I do think the calculation spreadsheet would work, just make sure to enter the correct measurement for the "Spring Attachment to Hinge Center Point in Inches". This is the measurement of the connection point of the strut to the hatch.

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Re: Hatch Gas Spring/Strut Calculator

Postby dales133 » Tue Sep 08, 2015 9:57 pm

do we have a maths?conversion wizard in the house that could help me with 5 minutes of thier time please!
im trying to work out my calculations and im terrible at maths and even worse with imperial measurements.

Edit.
The mrs worked it out but the struts i found are in nuton meters not pounds like in the calculator... this is doing my head in.
How do i convert nm to pounds of force,i dont even have the vaugest idea
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Re: Hatch Gas Spring/Strut Calculator

Postby noseoil » Wed Sep 09, 2015 7:55 am

It's fun, isn't it? Here's a link to something you can use. Basically 1 NM = 3/4#, actually .73# but close enough for what we do normally.

http://www.unitconversion.org/energy/ne ... rsion.html
Build log: viewtopic.php?f=50&t=60248
The time you spend planning is more important than the time you spend building.........

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Re: Hatch Gas Spring/Strut Calculator

Postby TomMaj » Thu Sep 10, 2015 8:37 pm

Dan-
Spot On!! Thanks for making the calculations, it worked perfect first time. Bought 50lb and 29" - Auto lifts by itself and shuts with around 5 lbs push.Feels the same as my SUV hatch. I would have wasted a bit of cash without your work. :applause:
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Re: Hatch Gas Spring/Strut Calculator

Postby derekbudd » Fri Oct 16, 2015 8:49 pm

I just installed struts on my new trailer following the calculator and it worked great the first time. I ended up with 28 inch 50# springs.
Thanks for the information.
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Re: Hatch Gas Spring/Strut Calculator

Postby Kanook » Mon Oct 19, 2015 1:32 pm

Worked perfect for me too. I went on the cheap. Spent about 30 min and $10 digging through a pile of new lift struts at a freight salvage/over goods store till I found two matching that fit the requirements and then used scrap metal I had and welded my own mounts.
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Re: Hatch Gas Spring/Strut Calculator

Postby Paradiseteardrop » Thu Nov 12, 2015 10:37 am

Hi I used the calculator for my Benroy hatch. It worked out to 80 LBS. LIFT IS PERFECT. After starting with 2- 40# I worked up in 10# stages and it ended up with 2- 80#. This was the figure I got in the first place. The lifts were in 10# stages at the RV store. Just round out the figures you get. 1.6123.-- 6 is over 5 so it can be a 2.000. Work out the figures shown a couple time then do with your figures.
Take care where you mount the bottom of the lift. 8-1/2 from the hinge pin. Lift the hatch to the height you want. Wacks on the forehead you do not want . Swing the bottom back to clear the hatch and mount.
Now to try and figure out how to load pictures here. This is my second one with FRP skin . Lee
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Re: Hatch Gas Spring/Strut Calculator

Postby Strop » Tue Dec 22, 2015 6:48 am

Hi all,

Just using the calculator, Dan thank you very much for this BTW :applause: :applause: , but I have a question.

a
After doing all the calculations I come out needing 97lb gas springs, that need to be 33.6 Inches long. Now my conversion for that is 430 Newtons and 853mm. The closest match I can find is 500N (112 lbs) and 830mm (32.7").

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Will 112 lb gas springs be too much? I can see that a safety margin of 50N has already been added in.

I can get struts that are 400N (90 lbs) that are 816mm (32.16") long.

Are they too small?


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Re: Hatch Gas Spring/Strut Calculator

Postby danlott » Sat Jan 09, 2016 12:58 pm

Sorry I have not been online much in the last year. I am happy that this calculator has helped so many people.

Sometimes the ideal spring lengths and weights for your hatch may not be available. If this is the case then I would do the following.

1. Using the calculator, adjust the "Stroke Length of Gas Shock" of the springs that you locate that are as close as possible to the ideal length and weight of what the calculator suggested.

2. Then adjust the "Spring Attachment to Hinge Center Point in Inches" based on the "Ideal Spring Attachment to Hinge Center Point in Inches" calculation.

3. The new "Spring Attachment to Hinge Center Point in Inches" value will adjust the "Required Force of Gas Springs in Pounds" value.

Play around with these numbers and compare them to the various springs that you are able to locate. You should be able to come up with something close that will work.

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