Chassis Mounting Methods

[David Root]

Thanx guys. Please see pic of the chassis drilling as of now. I measured chassis thickness at 0.120" so a standard 8-32 rivnut with grip range 0.70 to 0.120 should work.

The lower hole is tapped, so if I want to enlarge that hole and insert a rivnut, can it be inserted from the underside of the chassis, where I have unrestricted access, or does it have to go in from the upper side, meaning I have to get the tool thru the hole in the chassis upper lip?

[martin manning]

This rj Express chassis https://tubeamparchive.com/viewtopic.ph ... highlight= has Rivnuts installed on the flanges, and they are installed from the open side of the chassis. You could do yours the same or install them where you have drilled and tapped, and in that case they would be installed from the closed side of the chassis. You don't have a whole lot of distance from the center of the hole to the chassis wall, and the Rivnut needs a hole that is larger than the major diameter of the screw plus room for the bulge that is formed when the Rivnut is set in place. That means you need a flat surface around the center that is at least 2x the major diameter of the screw... Check the data sheet, though.

[Kagliostro]

[img:448:250]http://forum.amicidellavela.it/uploaded ... ttati1.jpg[/img]

K

[David Root]

Martin, thanx again. So I can do it from the closed side, that's good, as I'd like to have the closed side directly supported as the lips/flanges on these chasses are not welded to the sides.

The link you asked for on the tool I pictured is :-

http://www.aircraftspruce.ca/catalog/to ... uttool.php

I think I might get one.

Kagliostro, your pic doesn't come up for me. Do you have it in pdf or jpeg?

[martin manning]

Ah I see, that looks good and it's reasonably priced. I'm still a bit worried that you won't have enough flat area around the Rivnut with the weld bead there. If you Google Rivnut you can find instructions and diagrams showing how they work.

[tsutt]

Just an FYI all need for full strength is 3 threads for a fastener. .120 matl 32thds pi gives you 3.8 thds. in the weld however is a bad spot. if your going to put a rivnut there your going to have to spot face it. also weld heat softens the mat'l there.

[David Root]

Thanx again guys. The rivnut I need is 0.221 diameter, so it will be a tight fit on that side of the chassis. There is a bit more meat on the other side so no problem there I think.

I'll buy the tool and some 8-32 keyless rivnuts.

[Luthierwnc]

Similar to mhartman's post, I like these. They are more forgiving of slight misalignments. I use furniture capture bolts (also available from McMaster much cheaper than at Lowes) on the male side. They have an antique bronze surface that goes well with my builds and the broad head helps keep them from crushing the wooden box.

http://www.mcmaster.com/#captured-nuts/=m3gei6

Cheers, Skip

[David Root]

Thanx! If I have trouble with the rivnuts I'll try these.

[galtjunk]

I think what Brandon used were from Stafast.

Part number

S10324H2.130

You will have to thread the small holes on the base yourself.
Be sure and lube them with wax or oil before you insert the screws.
They gall really easily.