Re: Packaging 7854 scope for shipment?
Brad,toggle quoted messageShow quoted text
I have purchased four 7xxx 'scopes and had them shipped to me. None of them were packed well, not even remotely. The fact that they arrived intact has always surprised me. I've also purchased an HP 8566, HP 8660D and other very heavy items, most of which were not packed well.
When contemplating heavy, fragile items, physics is your guide, in particular Newton's second law (F=ma). You have to assume that the package will suffer at least a three-foot fall onto a concrete surface (e.g., from the shipper's conveyor system onto a concrete floor) and plan to protect the instrument from that sudden deceleration.
An instrument packed rigidly in a box that suffers such a drop will experience a very high G-force when the floor decelerates to box to zero m/s. This places tremendous strain on the internals of the instrument. For a 'scope, this includes possibly breaking the internal CRT connections. So the trick is to pack the instrument such that the packaging material will decelerate the abrupt stop against the floor as gently as possible. This requires that you use packing material that is somewhat compliant. Taking the instrument to someone who can package it in semi-rigid plastic-covered spray foam is very good if you can find someone to do this. Uline (expensive) provides kits for doing this yourself, but they are expensive. In my experience, polyethylene foam is the best for this. See, for instance, https://www.thefoamfactory.com/closedcellfoam/polyethylene.html (this is just a reference - I have never used this company, but the graphics are useful). Many products that one purchases contain products packed with this stuff, and I always save it. Barring a decent supply, one can buy it but it is, again, expensive. If you know of a place that routinely unpacks products and tosses the packaging material, sorting through the discarded material can result in finding some of this stuff.
Once one has a sufficient amount of polyethylene foam, the best packaging method is to suspend the instrument inside the box, cushioned on all six sides by the foam. Corner pads can work (think of how a DVD deck is packaged - two Styrofoam end caps which fit around the ends of the deck and keep it suspended in the box; styrofoam does not have much compliance and so transmits the force from a drop of the box directly to the product packed inside, so it is not a good packaging material, but the idea of suspending the 'scope inside two end caps or four corner pads is valid).
So, to pack a 7854, I would do something like the following:
1. Accumulate sufficient polyethylene foam. Note that polyethylene foam pieces may be cut and glued together using small amounts of epoxy to make custom-sized pieces.
2. Select a box that has at least 2" of space around the 7854. 3" or 4" will be better.
3. I'd lay a piece of foam in the bottom of the box which fits the entire bottom of the box (see #6, below) , cut another piece to fit up against the rear power supply fins and which extends rearward at least 1/2" beyond the rear enclosure that sits above the power supply, thus protecting the connectors on that rear enclosure.
4. Cut a piece of foam that fits between the front of the box and the plug-in bay (ship the plug-ins separately) and which extended up to just below the CRT bezel, leaving the CRT face and front panel controls at least 1/2" clear of the box.
5. Stuff foam down along the sides of the 'scope. These pieces would be longer than they are tall, but they need not run the entire length of the side of the box. The key here is to prevent side motion and provide compliance between the sides of the 'scope and the box. If the pieces move or slip, it won't matter as long as they stay captured between the 'scope sides and the box.
6. Add a final piece of foam between the top the 'scope and the box. Having that piece extend the entire front-to-back length and side-to-side of the top of the box will help protect the 'scope if the package is dropped on the edge at the front top of the package or either top corners.
One could also provide additional compliance by taping the aforementioned pieces to the 'scope (by running the tape around the foam pieces, not taping them individually to the 'scope) and then packing that whole assembly inside another couple of inches of softer foam or bubblewrap to provide a sort of two-stage deceleration protection.
Double-boxing is always a good idea. Using the softer foam or bubblewrap between the two boxes is a variation on the theme in the paragraph above. Peanuts are not useful at all for this. Peanuts are useless for anything with any mass because the packed item works its way through the peanuts. Typically, for something containing a large transformer, the corner of the item where the transformer is located works its way up against the box side, after which no protection is afforded.
Bubble wrap works OK if one uses a lot of good-quality bubblewrap. The stuff from Home Depot and the like is basically useless because the bubbles cannot sustain much pressure before they pop.
Newspaper is right out (to paraphrase Monty Python).
The best thing is to think it through by considering Newton's second law and how the packaging can provide sufficient gentle deceleration if the package is dropped.
HTH. Sorry for the extended bandwidth.
On 5/25/2019 4:23 PM, Brad Thompson wrote: