Shopsmith Forums

An air cylinder with a check/bleeder valve would provide one way speed control. With 12" depth a fair sized arm could be attached to the frame.

Would a door closing mechanism such as the ones used in commercial buildings to prevent doors from slamming be configured to do the job?
I have seen those things control some pretty heavy doors. Just a thought.
Bill V

wa2crk wrote:Would a door closing mechanism such as the ones used in commercial buildings to prevent doors from slamming be configured to do the job?
I have seen those things control some pretty heavy doors. Just a thought.
Bill V

Same principle. More easily procured!

I guess I need a life.
Anyway, looking on the internet I found "Stalibus Flap Stay Damper Gas Spring" which is intended to allow a drop lid down softly...Almost perfect.
It give a recommended max of a 24" door. My door is 44"...only 1/2" ply and I guess about 30lbs.
Do you think I should consider using 4 pistons, two in tandum on each side?
I guess on Amazon I could return them if they don't work, but I really don't like to return open packages. As a retired retailer it just goes against the grain.

kalynzoo wrote:I guess I need a life.
Anyway, looking on the internet I found "Stalibus Flap Stay Damper Gas Spring" which is intended to allow a drop lid down softly...Almost perfect.
It give a recommended max of a 24" door. My door is 44"...only 1/2" ply and I guess about 30lbs.
Do you think I should consider using 4 pistons, two in tandum on each side?
I guess on Amazon I could return them if they don't work, but I really don't like to return open packages. As a retired retailer it just goes against the grain.

IF I understand what you intended the lid is going to become the train platform, so while it may 30 or so pounds now it is bound to increase.
That is why a counterbalance system is such a good fit. You can add or subtract counter weights as the thing grows. Plus you aren't going to have a whole bunch of money tied up in it. Some rope or chain, a few pulley's and counterbalances. They could be something as simple as coffee cans filled with concrete to iron or lead sash weights salavaged at a recycle shop.

Another thought would be garage door springs attached to the cords to act as counter weights. Two old garage door springs, two pulleys and two cables, rope or chain would do the trick.

I built a toy box for my ex's little boys and had to solve the same problem, not only accidental but on purpose hand smashing.

The solution I came up with was to offset the lid slightly higher than the sides of the box and used rubber stoppers screwed to the edge of the box sides to level it, leaving a gap big enough for little hands and fingers under 99% of the lid. Knowing they would still find a way to outsmart me and injure each other where the lid met the stoppers, I also added lid safety supports so they couldn't slam it.

This is the safety support I used. They will lift/dampen a good bit of weight and you can use a left and right side support along with as many center mount supports as you need.
http://www.rockler.com/product.cfm?page ... te=ROCKLER

kalynzoo wrote:I guess I need a life.
Anyway, looking on the internet I found "Stalibus Flap Stay Damper Gas Spring" which is intended to allow a drop lid down softly...Almost perfect.
It give a recommended max of a 24" door. My door is 44"...only 1/2" ply and I guess about 30lbs.
Do you think I should consider using 4 pistons, two in tandum on each side?
I guess on Amazon I could return them if they don't work, but I really don't like to return open packages. As a retired retailer it just goes against the grain.

I checked these out, and agree that they look a little too light. It appears that Rockler sells the same model.

Then I realized that something like this could solve a problem we have with the electrical-enclosure door on a product my company manufactures. The door opens in the same orientation as your train table, but opens to full vertical for ease of access. If dropped, they tend to break the hinges. A damper plus a 90-degree bracket on the door should work well to solve this.

So I looked up the OEM of the Stabilus damper, and found the relevant product line here: http://www.stabilus.com/motion-dampers/. They can make them in most any configuration, but appear to sell only in volume through industrial and automotive distribution. But it did put me on the right track.

The generic term for the device you want is "Extension Damper". Google that, and you will get quite a few hits.

There is one currently for sale on eBay that might work for you: http://www.ebay.com/itm/Hydraulic-Exten ... 464wt_1400

Grainger sells a line of them, but they are very pricy: http://www.grainger.com/Grainger/gas-sp ... sst=subset

The most promising source for small quantities I found is here: http://www.spdhardware.com/catalog/DA%2 ... %20Dampers. They don't give load capabilities, but I found at http://www.guden.com/ItemDisplay/Standard-Dampers that the ones with 0.24" rods are rated for 3-50 lbf loads, and that the 0.315" rods are rated for 20-100 lbf loads. Note that these are the rated tensions on the rod, not the weight of the shelf. Those are related, of course, but depend on the mounting geometry.

I couldn't find good specs on the damping rates, but it appears that as the damping-rate designator letter goes up, so does the damping. Unless you are in a hurry for your table to open, I'd just get the heaviest damping available.

EDIT: I found an explanation of the damping-rate letters. It is at the bottom of page 4 of this document: http://www.spdhardware.com/documents/SP ... ttings.pdf

End fittings and mounting brackets are generally available from the same suppliers.

Now to go look at my own application ... thanks for the idea!