The BIG 500 series metal work thread! (to be...)

[kazper]

Seriously check out the emachineshop software and program.

I'm going to use them for my upcoming 51X stuff sled.

 

[emrr]

I'm a little amazed there's not a generic 500 sled being offered in perpetuity here.  No drilled holes, just the bent metal.

 

[Ptownkid]

I've considered that a few times...maybe I'll start a feeler.

 

[shabtek]

classicapi.

I had some sleds made by a local shop...ended up being like $1 each plus an hours labor to set up the tooling and make 'em.
They are fine, but not as nice as the ones Jeff has made.

 

[jsteiger]

I was gonna do a run of them a while back. I had them quoted to be exactly like my preamp brackets or sleds, with no holes anywhere. Brushed left side, which would probably get all scratched up and have to be user re-brushed anyhow. Like that they were gonna be $9.68 each at the store. I could see how much less for no brush/polish. My guys do a really nice job.

 

[mikefatom]

Alright, something doesn't make sense here.

Anyone with a 500 series reference drawing like the one from Speck or Black Watch Sound:

If the distance between the front plate screw holes and the center of the PCB is 0.438",
- and the PCB is 0.062" thick,
- and one is using 0.250" standoffs between the PCB and the L-bracket.
If we assume that the bracket is made of 0.050" thick metal and the overall width of the front panel is 38mm (1.496") as suggested by Sahib in one of the 51X thread.

Wouldn't that mean that the l-bracket would stick out the side of the front panel by 0.021"?

My simple math: 1.496"/2=0.748; 0.748-0.438=0.31; 0.31-(0.062/2)=0.279"; 0.279"-0.25"=0.029"; 0.029-0.050=-0.021"!!!
??? ??? ???

thanks

mike

How are your guys doing it? Jeff?

 

[mikefatom]

The only solution I can think of is to use 0.2" standoffs... but everyone seem to be using 0.25"  ??? ???

 

[jsteiger]

Owel and I had a conversation about his last year some time. I don't recall what he uses but I do use .25" standoffs. I also use 0.05" thick material for the L-bracket. Jens uses .25" standoffs too.

Yes, there is a little give and take but, if you investigate all of the current 500 series modules being produced by the main stream, you will find much more varying dimensions than the "cheated" 0.021". This is very common. I don't recall the exact dims, but when I measured all of the different API eq's I have, they were all over the place. Heck, on a certain range of 550b eq's, the left side of the rear metal enclosure is past the left side of the face plate by around .05"!!

The other thing to keep in mind are the racks by all of the different manufacturers. They are all over the place too. When I say "all over the place", I am talking +/-0.04" or so.

You could always use 6mm standoffs if you want. It will get you about .014" of that .021" back. I chose not to as I wanted to stay with more standard parts domestically.

FWIW, I am approaching 400 mic pre kits sold and have not heard back from anyone about a problem fitting an assembled module in a rack. Now watch, I will get 14 emails today about this! 

I think you would be fine. Take some time to search gs and you will find lot's of stories about modules that don't fit by amounts much great than what we are talking about here! Oversized transformers sticking way beyond the faceplate, on..and on...

Best, Jeff

 

[owel]

I use 0.25" standoffs too. 

There are no 0.2" standoffs.  You go with the standard size available.

Try redoing your math using 1.5" instead of 4.9". Doing the new math, it will be over by just 0.019"

Let's convert 0.019" to Metric... = 0.48mm.  Less than half a millimeter.

 

[jsteiger]

I use 0.25" standoffs too. 

 

...Let's convert 0.019" to Metric... = 0.48mm.  Less than half a millimeter.

A very small tolerance for manufactured products like we are talking about with mating connectors and so on.

Not to pat the guys around here on the back, but I am very confident in saying that we are much more concerned with trying to be in spec, accurate measurements and accurate layout than some of the main stream lot.

 

[mikefatom]

Thank you for the replies guys.

This is a bit disturbing to find this out. A standard should be just that, a STANDARD.

Can anyone confirm that the distance between the front panel screw holes and the PCB center is 0.438"??
This is what I REALLY want to know. What is that distance in a 51X rack?

Thanks,

Mike

 

[jsteiger]

Yes Mike, the 51x rack is designed at 7/16" from PCB center to center of module. Cemal worked from the spec sheet and an API 6 space rack from Volker. Now, that distance can vary slightly due to screw holes and where the card edge connectors get soldered to the PCB.

This is just a tolerance I think.

Look at the 1.75" rack space and how many different sizes people make their front panels and cases. It is a standard but is varied from all the time.

I will take a pic of a 550b module later today. It is their standard and you will see how far off it is!

 

[owel]

This is a bit disturbing to find this out.

Not really. Look at any mechanical drawings and you'll see tolerances specified... +/- 0.whatever. 

There is the nominal dimension specified in the drawing. Say 1.5"

But in the real world, the cutting machine or grinding machine will introduce it's own errors, so you won't  exactly get your nominal dimension.  But you can specify a "tolerance +/- whatever" of what is acceptable to you. (so some parts may come in under, some over your nominal dimension but if it's within your tolerance specified, it's still OK.)

Of course, nothing is free in the real world. If you specify a real tight tolerance in the finished product... say +/- 0.0001 then be prepared to pay dearly for it.  But do you really need the part to be that precise?

Now if all modules are 1.5", and each panel have manufacturing tolerances +/-... (and hopefully not all of them on the + side), it may be possible that all may not fit in the rack IF the rack holes are exactly 3.0" (and did not account for tolerances).

So hopefully, the rack manufacturer introduced some "allowances" in between the mounting holes so any 1.5" module that is within the +/- tolerance will still fit side-by-side, even if all of them end up on the high side of the tolerance.

But there's this guy named Murphy.... and he decreed a law.

 

[dmp]

I think the small slop can be taken up in the center distance to pcb, since the pots can be moved around in the holes a bit usually. I've made about 10 and could get them all aligned fine to go in the rack.
Lately I've been wondering why aluminum? Steel is much better for shielding, yes?

 

[SIXTYNINER]

hey jeff 
a good picture about (as you posted in other thread about wide of front panel)
could be a very good info

Yes Mike, the 51x rack is designed at 7/16" from PCB center to center of module. Cemal worked from the spec sheet and an API 6 space rack from Volker. Now, that distance can vary slightly due to screw holes and where the card edge connectors get soldered to the PCB.

This is just a tolerance I think.

Look at the 1.75" rack space and how many different sizes people make their front panels and cases. It is a standard but is varied from all the time.

I will take a pic of a 550b module later today. It is their standard and you will see how far off it is!

 

[Crusty2]

Standard PEMs are shorter than an equivalent standoff, so you would get your error back (and then some): http://www.pemnet.com/fastening_products/pdf/sodata.pdf

 

[burdij]

Not trying to be a jerk but I don't know where you're getting your info. 

Let me correct one error in my original post. The alloy I am currently using is 3003, not 1003. I am getting my information from my metal supplier and from experiments I have done with my China-brand break and shear. Here is a useful chart:

3003 in 1/16 inch thickness is the max that can be used for a zero radius 90 deg. bend.

 

[mikefatom]

Standard PEMs are shorter than an equivalent standoff, so you would get your error back (and then some): http://www.pemnet.com/fastening_products/pdf/sodata.pdf

That's what I had noticed. I believe that will solve my problem!

Thanks to everyone helping out here.

Cheers

Mike

 

[Denyle Guitars]

Lately I've been wondering why aluminum? Steel is much better for shielding, yes?

For the L bracket? Most commercial products use steel. I use 20ga steel in my DIY ones. Thin enough to bend easily but thick enough to be rigid and hold a countersink. The downside is it needs a coating to prevent corrosion.

 

[jsteiger]

FWIW, Volker and I went in on a big batch of the blank L-brackets or "sleds", as they have been called. Sent in a PO early this morning. Should be about 3 weeks delivery. They will be 6061-T6 exactly like my VP2x brackets except no holes at all...anywhere. Left hand side will be brushed.