Dumblelator - mounting of internals

[jakehop]

Hi guys,

I have a question that's been bugging me for quite some time.

Last month I had a customer who wanted me to build him "something to make the effects loop useable" for his Matchless (why they make their loops so useless, I don't know). I built him a D-lator. The 1U-enclosure I used had some flanges on the sides which I mounted a drilled eyelet-board to, which spanned the enclosure's total width. I also mounted the transformer and everything else on it - it worked very well.

The guy had a 3U rack-case and two of the spots were taken by effects processors. I know it's not OK by the ISO-standard to have bolts and nuts stick out from the chassis, unless you countersink that part of the chassis, so they don't stick out from the chassis.

Now for the question: I see in here that what looks like the standard way of mounting the circuit boards is by having nuts and bolts stick out from the bottom of the enclosure. Will that thing mount in a rack case with only 1U left? Is there something I've missed?

Kind regards, Jake

[guitardude57]

If you put the D-lator in the bottom space (first) and there are no screw/bolt heads poking out on the top....should give no problems.

You may also consider using 90 degree brackets to hang the boards from the sides. Screws, heatsinks etc., can be stick out on the sides without too much trouble, as long as it will slide past the rack rails.

Typically any screws used in stand offs or other hardware mounted to the top or bottom, is done with countersunk holes and flat head/beveled screw heads..........so they don't stick up any higher than the cover plates.

At 1 3/4" rack height for a space, nothing should be past that dimension.
So if things are sticking out, rework it or place in bottom space where you have a small amount of extra room in bottom space in some racks.

If bottom space is against the rack case floor.....it won't fit as is.

I would rework it so it would slide in whichever space the feller wants it in. There are some rack devices that may produce noise in the audio path related to location of sensitive devices. Some digital FX displays can project noise that can be picked up.

If there are no shielding issues there will probably be no issues. But you don't know until the stuff racks together.

Hope this helps..............

[Structo]

It doesn't sound like too much work to countersink the holes and use flat head screws, then they would be flush with the sheet metal.
Hopefully your chassis is thick enough to allow that.

But I know some of the rack mount cases can be rather thin.

[jakehop]

I think that countersinking holes either requires some serious tools, or some serious know-how. I'm a learning-by-doing-or-perhaps-reading-stuff-online kinda guy, and I haven't been able to figure it out yet. Gotta do some studying.

Anyhow, my enclosure had some mounting holes. I just used a piece of fiber board to mount everything on horisontally, with the tube sticking out the back. It worked great!

Can't help but keep wondering about it though

[jakehop]

OK, like 5 minutes on Google helped a lot. Sometimes you just happen to type in the right stuff and get the results you need!

What I need is a "dimpling tool" - a kind of device that uses male and female dies to make the countersink.

[img:708:756]http://www.vx-aviation.com/rv-9a/photos ... pler_1.jpg[/img]

[RevD]

You don't really need fancy dies or anything. Use a longer version of the machine screw flathead you want to use, get a nut that is a size or two larger in diameter than the screw your using and then put the nut on the screw your using and crank it down, the screw your using will pull the metal up into the void around it (inside of the oversized nut) and you'll have a countersunk dimple. I used to use this trick with a piece of pipe (instead of the nut I was talking about using above because it was a much larger 3/8's inch bolt I was countersinking) a 3/8" flathead bolt and a nut with a washer to span outside of the pipes o.d. I used this in a construction application where a metal door frame was being put into a concrete wall and needed to use expansion bolts. In the shop we used a dimpling die, but this was on the job so I needed something more portable. I'll try to sketch something... Make sure the screw JUST fits in the hole drilled so it won't get to large when stretched while dimpling the chassis. If its aluminum go slow and don't over do it as you'll crack it, just sneak up on it and watch carefully. I havent tried this on the aluminum chassis and don't know its thickness so please be careful with it.

[guitardude57]

There you go.....now we are cooking with gas! Good idea RevD with the over sized washer and bolt to draw the metal in.

[Structo]

Well while that should work, I'd be afraid of distorting the sheet metal.
Especially if it is steel.

The tool I was thinking of was this.

[img:200:200]http://www.ttrackusa.com/Assets/09_imag ... 200_07.jpg[/img]

They are mainly used on wood but I have used them on metal as well.

But this tool may require that the gauge of the material be thicker to allow the screw head to be flush with the surface.
So this may work better on thick aluminum.

[guitardude57]

That would work but be very careful.

Those are for wood, but aluminum is soft.
Easy on the pressure. If you go out of plumb, could grab the material, ouch!
Use drill press for sure.

They eat quickly. Do a little....stop and check. Repeat as necessary.

[Structo]

Yeah it was aluminum that I have used these on.
They work great to deburr a hole after drilling.

For the screws on the rack box, you could try to use some pan head screws. Those are probably the smallest head screws.

Otherwise screw things to the side of the chassis.

[ChrisM]

Yeah it was aluminum that I have used these on.
They work great to deburr a hole after drilling.

Thanks for the tip. I have been having a hell of a time trying to find a deburring tool locally.

[Structo]

I bought mine at Lowes.

[M Fowler]

For deburring you can use the stone bits for the dremel as well.
They come in many sizes of cone shapes.

I also use what Structo posted, the deburring bit, I have one for steel use got it a long time ago, 30 some years ago.

For tapering a hole, small bit for the #6 bolt or whatever size and then a 1/4 bit to cone the hole carefully of course works every time for me. I gentle apply pressure and take my time.

The last time I did this was for board mounting bolts that are under the ODS PT. As well as bias board on side.

[Structo]

Mark I have used that method as well.
You just have to be very careful with the larger bit so you don't go too far.
A drill press with the depth stop set would be the smart thing there.

I was looking at the Hammond box I used for my Dumbleator and it is made from steel.

It is .04" thick so I don't think it possible to countersink a screw by drilling with the cone shaped tools.

I'll have to give one of those die type counter sinks a try sometime.
I'd be curious if that process could warp the surface of the steel if you did it a lot on one side.

[M Fowler]

I think it would warp the steel being its such a small dimple area without appling heat.

I can't remember the Street Rodder catalog I get periodically with all these great metal working tools and dimplers are shown often.