The chassis are here

[EL34]

This page has conversions
http://www.broward-bolt.com/images/MetricConversionInformation.pdf

Stripping is easy if you use soft bolts or apply to much pressure
that's why I would go with steel rivet nuts instead of aluminum
#10 look to be about 4.86 mm
I like to use Stainless Truss head bolts

[kagliostro]

So 10-24 = 5mm


5mm steel rivet nuts are not difficult to pull

K

[DummyLoad]

k
#10 major thread dia is .190" or ~4.82mm

1/4" major is .25' or ~6.35mm

--pete

[kagliostro]

Thanks Pete

k

[Willabe]

no one here has ever stripped a nut or screw, right?   

Yes that's true, it can happen and does.


              Brad      

[PRR]

Riv-Nuts are prone to spin in the hole.

This is not supposed to happen if the chassis thickness is suitable, and the assembler gets a good snug fit. However I've spin a few on older sheet-metal items.

#10 thread in steel is good for at least 300 pounds pull. The chassis flange will bend all-to-heck before the screw breaks. But ignore that. Four such screws will hold 1,200 pounds. Assume a 30 pound chassis. The screws will not break with a 40 Gee shock/drop.

We might like a 50 Gee rating. (50 Gee is about what a human can survive with full body-straps, such as NASCAR racers; in an amp's life it would be a bad truck-wreck or a head-on fall off a tall stage.) Then four #10 can handle 24 pounds of chassis, which covers a lot of amps. And in fact you hope your amps never get close to 40 or 50 Gee. (Transformers and speakers shear-off.)

The chassis in this thread is essentially an "18 Watt" and probably sits under 24 pounds all-up. Four #10 is ample.

SVT should be using 1/4 bolts (and a much stronger flange).

[kagliostro]

Riv-Nuts are prone to spin in the hole.

yes, that can happen

this one are more prone


this one are less








---

if you need to remove, isn't difficult


K

[EL34]

I ordered these

Material: Steel-Yellow Zinc
Thread Size: 10-24 UNC
Grip Range: .020-.130

The aluminum chassis are .09 " thick so it is well withing the grip range of the rivet nut
They have the knurled edge so they should grip good

[kagliostro]

With steel on aluminium the grip is really good

I think that you'll never have problems

Franco

[EL34]

I updated the chassis images in post #1

http://el34world.com/Forum/index.php?topic=17502.msg175655#msg175655

[terminalgs]

I'm a big fan of clip-nuts/u-nuts on a flange.  different manufacturers have different shaped nuts,  some with more depth clearance than others. Au-ve-co, Dorman, Hillman,etc..

The rivet nut seem to be charmer here, but the simplicity+strength of the slip-on u-nut has got to be the superior option here.  no special tools required, no chance of a spin,  EASY to replace.

I think rivet nuts earn their place in the middle of a piece of sheet metal, not on a flange.

On the bottom side, oval screws with finish washers.

[EL34]

I'll have both in stock
The 10-24 clip nuts and the 10-24 rivet nuts
people can choose what they want and it's up to them to do the installation, so I am out of the loop 

I like the clip nuts also for simplicity
It will take someone a bunch more labor to install the rivet nuts

You still have to drill the mounting hole out to a larger size with the clip nuts
If you don't, the bent spring part makes the chassis sit way up in the air
I drilled a 3/8 inch hole and the springs fell right into the hole

Here's an image of a clip nut slid onto .0625" thick garolite - Top image
The bottom image is the clip nut dropped down into a 3/8 inch hole

So in the top image, the clip nut would hold the chassis up in the air quite a bit
Keep in mind also that the chassis will be .09 inch thick aluminum

I like using Truss head bolts because of the oversized head

[EL34]

I got the 10-24 Rivnuts in today
I installed one in some .09 think aluminum along side a clip nut

I thought I would like the clip nut better, but now I have switched over to liking the rivnut better

The rivnut was harder to install, but it is locked down tight once it was installed
i had to grab the rivnut with a pair of vise grips to keep it from spinning while you crank down on it with a 10-24 bolt

The rivnut needed a 19/64 inch hole
The clip nut needed 11/32 inch hole in order to make it sit flush against the surface

Here's a pic of both, side by side

[PRR]

> i had to grab the rivnut with a pair of vise grips to keep it from spinning while you crank down on it with a 10-24 bolt

You probably shouldn't do it that way; even the least little spin will weaken the serrations which prevent spin in use.

EL34 - No, I only grabbed the smooth upper part with a vise grip, not the lower serrated section.
You can see one of the teeth marks


The only only way to keep it from spinning is to use a large levered tool that pulls the bolt head like a pop rivet gun would

[EL34]

Crap, I hit modify by accident on your post above PRR

I grabbed the upped smooth section only with the vise grip
Here is a close up
You can see the tooth mark where I grabbed it with a vise grip to keep it from spinning while I cranked down on it with a hex head bolt

It collapsed fairly easy once I had a grip on it with the vise grip

The correct tool would only pull the bolt head like a pop rivet gun, but I don't have that tool
Most people that install these will not have the real tool either

[lego4040]

hey Doug how about using a small diameter hex bolt, two washers and a nut and use it as a press? instead of vise grips and crushing part., put part on chassis, put bolt thru and tighten up.

[EL34]

I don't think I explained how I installed the rivnut very well
I did use a bolt and washer to compress the rivnut

I only used the vise grips to hold it to keep it from spinning.
You can't turn a wrench without the rivnut wanting to spin

Once the rivnut compresses a tiny bit, you don't need the vise grips any more because the rivnut starts to dig into the metal

Here's a picture showing how I compressed the rivnut
The allen head bolt was fine and the allen wrench had plenty of power
A hex head bolt and wrench or socket would have even more power

[lego4040]

I see, when you said collapsed I thought the thread part ovaled and it was ruined.

[EL34]

I see, when you said collapsed I thought the thread part ovaled and it was ruined.

The threaded section is pretty beefy, it would be hard to oval out or squish the threaded section


The serrated section is thinner and that is why it mushrooms out when pulled by a tool

[DummyLoad]

doug, would you kindly provide the PT end-bell cutout dimensions please?


thanks,


--pete

[EL34]

Hi Pete,

It is cut out for the 18 Watt PT that I sell
It's the same hole size cutout as the 18 watt chassis I sell

2.625" x 2.5"

[DummyLoad]

Hi Pete,

It is cut out for the 18 Watt PT that I sell
It's the same hole size cutout as the 18 watt chassis I sell

2.625" x 2.5"

cool. looks like the vibrolux/tremolux PT and the hammond 273CZ/373CZ PT will fit. we can get 400-440V B+ in a build.


--pete

[EL34]

Cool, I did not know that
Thanks for that info

[kagliostro]

Ciao Doug

I would like to know if you think is better to have the small wings of the chassis (where you fix the nuts) bended outside of the chassis or inside the chassis ?

In your plan the wings are outside, but have you considered also inside bending ?

Thanks

Franco

[EL34]

Hi Franco,
Mojo likes to have the flanges bend out on their chassis and since they are making it to sell I went along with it


On a small chassis like this there would not be any room to bend inward and have the bolts clear parts
The bolts and rivnuts would be an issue

[kagliostro]

I understand


Thanks


Franco

[DummyLoad]

Cool, I did not know that
Thanks for that info

Hi Pete,

It is cut out for the 18 Watt PT that I sell
It's the same hole size cutout as the 18 watt chassis I sell

2.625" x 2.5"

cool. looks like the vibrolux/tremolux PT and the hammond 273CZ/373CZ PT will fit. we can get 400-440V B+ in a build.


--pete

bad news: :-(

i confirmed a pair of vibrolux/transformers i have in stock with my calipers: the 2.5" dimension works but the 2.625" dimension does not. the hole will need to be opened up about 85 thousandths. i measured transformers from two suppliers, one is a mag comp from triode elec., the other is a hammond 290CX. to make either fit, one option is to carefully remove the inner end bell, however, as we've leaned from past efforts removing the case bolts, that it can have disastrous consequences unless you apply heat.

i think relieving the opening would be the route to take. i have not ordered a hammond 273CZ yet, but i'm not too sure about that part either since the specs state 2.06" x 2.685" +/- .063". i'm betting hammond used the same end bells as the 290CX part which measures 2.15" x 2.710".

personally, i can do this on my vertical mill, but others may find it more of a daunting task. knocking out 85 thousandths (40 thousandths/side) with a file, nibbler, or dremel isn't going to be trivial.

sorry if lifted anyone's hopes, self included, but it appears the none of parts i mentioned initially will install without some form of additional fitment work. my apologies. 

--pete

[John]

If the chassis is aluminum, it might give that much when you draw the bolts down. In fact, if you made a small cut at one end (at the corners) where you need the space, I'm almost sure it would, it would let the alum. bend. Drill a small pilot hole to keep the cut from becoming crack?

[EL34]

We will have to wait and see what the actual hole size is once I get one here


I am having Andy make me 10 of these with no holes
He said that is not a problem

[DummyLoad]

We will have to wait and see what the actual hole size is once I get one here


I am having Andy make me 10 of these with no holes
He said that is not a problem

that's great news. are all 10 spoken for? the blanks would then allow us to use X mount type iron. perhaps as revision in the future, would you be willing to open up the PT opening to accommodate the vibrolux/tremolux PT?

attached is a feeble attempt to recreate the machined version. not sure about exact placement for things like the PT location, i rough estimated tracing off the oblique drawings you posted earlier.

the blue can cap is a feeble representation of the lay-down cap inside the chassis: i'm too tired and lazy to create the object's horizontal view now. i'll fix that in the next rev.

--pete

[EL34]

that's great news. are all 10 spoken for?

No, I have not told anyone until just now

would you be willing to open up the PT opening to accommodate the vibrolux/tremolux PT?

I doubt it because Mojo is selling them also.
It's a joint venture and so both parties have to agree on the specs

This is why it works for me. I don't have to contract someone to make 100 or more chassis and tie up all that money
Mojo makes them and sells them to me and they will also sell them on their web site

I can just have  a few on hand and I can get them in one day if I need more.
Mojo is in NC also

Not only that, I can sell them cheaper than what Mojo sells them on their web site to the general public because they give me a huge discounted price
I get an much better price than the other wholesale accounts do

Anytime you can not tie up you money in business, it's a good thing

[MakerDP]

Know the selling price yet?

[EL34]

No, I don't have an cost figure yet
Still waiting on Andy to work that out


I want to sell these as cheaply as is possible

[DummyLoad]

drums fingers on lab bench... donde estan sr. douglas?     


i have all this crap on the breadboard i'd really like to stuff in a new chassis instead of the breadboard parts bins...  hint, hint.   



--pete

[EL34]

Got an email from Andy yesterday
He is making 50 chassis just to start off with and he is ready to go on that deal

I am taking 25 of the chassis and of those 25 I am having 10 blank ones made

I am double checking with Andy on the prices and waiting for a reply

I will do a initial offering that is really good to you guys
So far it looks like the chassis with holes will be cheaper than chassis at other sites sell with no holes?

Waiting to see what the blank chassis cost will be and then I'll be able to quote a selling price

[DummyLoad]

cool. thanks for the update. 


--pete

[lego4040]

 

[Ken Moon]

Woo-hoo!

<<<< sound of soldering iron heating up >>>>

 

[lego4040]

For those wondering what PT they might want to use for this chassis. I have a spare 290cax and I took Measurements, I don't think will work, to small. Add that to list of what may/ may not work

[sluckey]

And that's exactly why I prefer a blank chassis. When you get a pre-punched chassis with a big rectangle hole cut for a particular laydown style transformer, you're kinda locked into using that particular transformer. There may be several transformers that will fit, but you really limit your choices. I also prefer standup transformers for ease of mounting and the extra room they provide under the chassis.

[Ed_Chambley]

And that's exactly why I prefer a blank chassis. When you get a pre-punched chassis with a big rectangle hole cut for a particular laydown style transformer, you're kinda locked into using that particular transformer. There may be several transformers that will fit, but you really limit your choices. I also prefer standup transformers for ease of mounting and the extra room they provide under the chassis.

+1
I hope the price is right.  I want a few of the blanks myself.  I am thinking they will be cheap enough where I don't have to make smaller boxes anymore.

[EL34]

I found out that the blanks are costing me the same as the ones with holes.
Because they are cut by a laser on large sheets, there is no human labor involved to cut the sheets while they are flat.


Both chassis get and exterior cutout and then the holes only take a minute to cut


The human labor is in the bending of the chassis and both chassis have to be bent


I will do an introductory price to forum members at $39 per chassis, holes or no holes
Better get dibs on the no holes version because Andy is only doing 10 of them.

[Ken Moon]

I would like to get 2 with the pre-drilled holes, please.

Do I watch your catalog and wait to order, or can I pre-order them now?

Thanks, Ken

[Ed_Chambley]

I want 2 with no holes and 2 with holes.  1 set of adapter plates for the power tubes.

My dibs!

[EL34]

Ok, we will keep tabs here


8 with no holes left
Plenty of chassis with holes

[DummyLoad]

one blank and 2 punched for me please...

--pete

[EL34]

7 blank left
 

[terminalgs]

I'll take one with holes.

[jojokeo]

I'll take two with NO holes please? Thanks Doug.
 
Joe

[EL34]

5 blanks left


thanks all