Mounting HP7970e 9-Trk 1/2" Tape Drive

[Brent Hilpert]

On 2019-Feb-06, at 12:24 PM, Chuck Guzis via cctalk wrote:

> On 2/6/19 11:25 AM, Jay West wrote:
> 
>> Yes, it's all "standard 19 inch" but..... the HP gear and mounting
>> kits of that time expected certain things to be present in the rack
>> design/construction well beyond just the space between the vertical
>> posts.
>> 
>> As I recall, on the left, the flange (where mounting holes are - on
>> the right) does not have mounting holes. And drilling and tapping
>> would be difficult because a 2 inch thick piece of solid metal from
>> the side of the casting covers those...<snip>
> 
> Okay, here's what I'm talking about.  Take a look at PDF page 6 from
> this document:
> 
> http://bitsavers.informatik.uni-stuttgart.de/pdf/hp/tape/7970/07970-90383_7970B_7970C_Operating_and_Service_Manual_upd_Feb76/07970-90383_7970B_7970C_Operating_and_Service_Manual_Section_1.pdf
> 
> This shows very clearly the naked "box" without the transport works.
> Said box is aluminum, with 1/8" or so thick flanges on each side.
> 
> Note that the right side has 3 mounting slots (and the transport has 3
> "notches" to make room for bolt heads and washers.
> 
> Now look at the right side of the drive box.

(I take it you mean "now look at the -left- side".)

If you drill holes in the left-side flange for rack mounting, you have to be able to access them at mount time,
which is not possible with the drive fully assembled.

However, looking at my 7970A, it appears you could separate the cast-Al transport frame from the chassis box
by unscrewing the 4 exterior left-side hinge screws, as well as detaching all the cabling between them involving
a wire harness and a dozen-or-so plugs.

This would have the benefit of splitting up the weight involved in the mounting process.
Holding the transport frame and aligning it with the hinges during reattachment while trying to get the screws
in place might nonetheless require two people.

In a slightly-alternate design, HP might have made the left-side bezel over the manual controls removable,
giving access to the left-side flange without detaching the transport frame, but that would also require a slight modification
to the casting near the screw holes for clearance for the screws.

For loading concerns raised by Jay, in both cases (designed-for steel bracket vs drilled flange) the weight of the drive ends up being
borne by 4 rack-screws on the left and 3 on the right.
The difference would be steel vs Al bearing down on the 4 screws on the left, and some altered bending moments on the
left side of the Al chassis box around the flange, offhand I wouldn't think it would matter.



>  Note that the hinges for
> the transport are secured to a similar flange, but without any mounting
> holes.   I propose that drilling a couple of mounting holes to match
> rack spacing and countersinking said holes so that they don't interfere
> with the transport body would do the trick.  My rack uses cage nuts on
> the rails, so there would be no fiddling with nuts and bolts.  I'd
> probably also feel better if the rear of the drive were secured to the
> rack also, but I haven't worked that one out yet--nor am I likely too,
> as my current setup works just fine without the danger of hernia.