The chassis are here

[EL34]

I am collaborating with Mojo to have a small chassis made that would be suitable for a 18 Watt type amp head
It is based on the Seeburg chassis I built my Hoffman Stout in, which is one of my favorite amps



But since I am designing the chassis from scratch, I can create it any way I want
But Mojo also is going to sell it so they have some input on what they want also

This is what I have so far
12 inches long x 6.5 inches deep x 2.5 inches high
.09" thick Aluminum - Standard Mojo aluminum chassis thicknesschassis
Mojo makes custom faceplates and so you can design your own
I will probably have Stout plates made and for sale

The front panel has 6 x .375" holes and an indicator lamp hole
You can fill the .375" holes with switchcraft jacks or pots

The top has 2 holes for 9 pin sockets and 3 x 8 pin socket holes
I plan on stocking adapters to make the 8 pin holes into 9 pin socket holes
OT and PT holes are for the Heybour 18 watt tranny set I stock
There is an extra set of OT holes for Deluxe sized OT's
The choke holes are for a small Fender sized choke
There's a couple rubber grommet holes on either side of the OT

The back holes are - 
IEC receptacle,
Fender fuse Holder,
On/Off switch,
Rotary impedance selector switch
2 speaker jack holes

There is an image below that shows how the Hoffman Stout Board fits inside the chassis
I added a couple cap bracket mount holes to the right end so you can mount a 40x20x20x20uf filter cap on the inside wall
The cap will not fit above the PT and so it sits below the rectifier socket with lots of air space

[drew]

The Brown Note guy had a batch of "experimenter" chassis made some years ago that had some nice features, including:

1.  Small oval holes adjacent to the potentiometer holes to receive the little tab on the mounting face of the pot that is meant to keep it from spinning if the nut loosens;

2.  Holes intended for toggle switches have rectangular key at top to correspond to keyway in switch bushing;

3.  front panel has several sets of holes for input jacks, to permit various configurations (one or two channels, hi/lo inputs or single input, etc.), also a number of toggle switch  holes interspersed between pot holes to permit many different knob/switch configurations

4.  Hole intended for impedance selector rotary switch has three small irregularly-spaced holes around it (I assume these are intended for the tabs on different brands of switches?);

5.  Fuse holder hole has flatted sides -- is this so that the hole could be used either for a fuse holder or for a traditional power cord with stress relief?

I can take a couple pictures if you like.

Also, with regard to the power tube socket question, maybe consider having the chassis have the two preamp sockets as drawn, then next to that have a rectangular cutout, over which a plate with two or three octal or noval socket holes could be attached.  You'd have to stock several versions of the plates, but it might be worthwhile, since it would allow a customer to build anything from an 18watt variant with an EZ81 to a 5E3 to a 6v6 plexi into one of these chassis.

[DummyLoad]

1.  Small oval holes adjacent to the potentiometer holes to receive the little tab on the mounting face of the pot that is meant to keep it from spinning if the nut loosens;

not all pots are keyed on the same side. the impedance selector switch is another story: since it's a higher effort to actuate, spec the exact switch and machine the key hole.

I thought about having the power tube holes be 8 pin socket holes and using a block off plate for 9 pin sockets

that would be a cool feature: can then option for 6V6/6F6 tubes. maybe a smaller prod. run with octal only and the bulk all noval? 

the octal rect. socket is fine. wouldn't consider using a noval rect. in something like this.

my 2cents.

PS: how about a 17" x 8" version for the 1 ch. AB763 or JTM45 or bassman? spec the 50W marshall iron you sell for all 3 versions. the reverb OT would be fender. dual pattern machining for either fender or marshall choke.

--pete

[EL34]

Just my .02

1.  Small oval holes adjacent to the potentiometer holes to receive the little tab on the mounting face of the pot that is meant to keep it from spinning if the nut loosens;

Not worth the extra cost for the few pots that actually have that tab. I solder a buss wire down the back of mine and the pots stay put

2.  Holes intended for toggle switches have rectangular key at top to correspond to keyway in switch bushing;

Maybe, but Mojo does not do that in their chassis. Not really a problem that I have ever seen since you are throwing the switch up and down and not twisting it

3.  front panel has several sets of holes for input jacks, to permit various configurations (one or two channels, hi/lo inputs or single input, etc.), also a number of toggle switch  holes interspersed between pot holes to permit many different knob/switch configurations

Small holes for mini toggles can be easily drilled if you need them. Can't put holes between pot holes because the spacing is set up for chicken head knobs and the beaks will hit anything between the pot holes

5.  Fuse holder hole has flatted sides -- is this so that the hole could be used either for a fuse holder or for a traditional power cord with stress relief?

Yes, Mojo does that on some of their chassis, I am specifying a double D hole for the fuse holder


Thanks for the input

[EL34]

I thought about having the power tube holes be 8 pin socket holes and using a block off plate for 9 pin sockets

that would be a cool feature: can then option for 6V6/6F6 tubes. maybe a smaller prod. run with octal only and the bulk all noval?
the octal rect. socket is fine. wouldn't consider using a noval rect. in something like this.

Thanks, I'll see if Andy at Mojo already makes block off plates. I think it would be nice to be able to use 6V6 tubes

Hole intended for impedance selector rotary switch has three small irregularly-spaced holes around it

My 3 way rotary impedance selector can be cranked down really hard with lock washers. I have not see one move yet that was properly installed

PS: how about a 17" x 8" version for the 1 ch. AB763 or JTM45 or bassman? spec the 50W marshall iron you sell for all 3 versions. the reverb OT would be fender. dual pattern machining for either fender or marshall choke.

Mojo already has some chassis sort of like that. I stock their 18 watt aluminum chassis. They also have a 50 watt plexi chassis and several generic Fender chassis

Thanks for the input guys

Here's the back drawn with a Double D shaped hole for the fuse holder

[terminalgs]

How flexible is the cap can location?  It looks like it is directly under the octal rectifier tube.  I know it needs to clear the bottom of the PT as well.  its not super critical, but if you have room to move it toward the front, it might open up access to the octal.


I think cutting holes for octals instead of novals for the power tubes is a great idea.  It seems that a single square sheet metal adapter to provide for the noval is something mojo could sell for any of their chassis equipped with the same octal cutout. 


Once the power tubes can be octals, the chassis is prime for a dual purpose of a 5E3 amp as well (or many others).  Maybe a well placed 3rd bolt hole would provide other OT options (if the 5E3 OT has a different bolt span there...).


These are small nuances...  everything looks fantastic!

[EL34]

How flexible is the cap can location?  It looks like it is directly under the octal rectifier tube. 

It won't fit above the power tranny
Not really a problem where it is. You wire that socket one time and you are done with it
There is a pretty good air gap between the two
And the heat rises so the socket is on top of it
My stout in the picture below has the same location. It was built in 2005 as is ticking away without any problems

I think cutting holes for octals instead of novals for the power tubes is a great idea. 

Yeah, I am contacting Andy at Mojo to see if they have already done something like that
I drew up individual block off plates in case you want to build a single ended amp
The single block off plates would be round and bolt into the 8 pin sockets mounting holes

Once the power tubes can be octals, the chassis is prime for a dual purpose of a 5E3 amp as well (or many others).  Maybe a well placed 3rd bolt hole would provide other OT options (if the 5E3 OT has a different bolt span there...).

I like that, that's a good idea

Here's the insides of my Stout. The cap is under the rectifier

[EL34]

Some new drawings with some changes

I added another set of OT mounting holes that will accept the 022905 Deluxe OT

My idea for using individual block off plates
I modified the chassis holes in the drawing below to have cutouts so that the 9 pin mounting hardware can fit through the 8 pin socket holes
The adapter has extensions so you can bolt the 9 pin socket in place with #4 screws and #4 keps nuts
I may be able to make those extensions a bit small and use #4 self tapping screws to mount the 9 pin sockets
The small diameter ring around the outside of the socket drops down into the 8 pin hole on the chassis

I made an adapter on my 3D printer this morning and mounted a 9 pin socket into it
I think this idea may work fine
I am sure Mojo would have no problems cutting the adapter in two separate pieces on their water jet or their laser cutting machines

[terminalgs]

very cool! 

[tubenit]

I think you have come up with a very versatile chassis.  Nice design to it.  The octal to noval adaptors are nice.

With respect, Tubenit

[EL34]

Thanks Guys


I sent the drawings off to Andy at mojo to see what he thinks about the adapter idea

[EL34]

Got an email back from Andy at mojo


All those changes are no problem and they already make a 9 pin to 8 pin adapter
It offsets the 9 pin socket in the 8 pin hole

It looks way simpler to make than my idea and you don't have to alter the 8 pin holes on the chassis
I would just go with their adapter

It looks like this

[Ed_Chambley]

How much more would it cost to make a program change mid run on the chassis whereas you could make some for 9 pin and some 8 pin.  I do not know how many you are making, but it would not make constructing the chassis any different.  Only a program change and keep right on cutting.  I guess whoever makes them is using water blast cutting.


I mention this because you are gathering more of your items together for a build on you site.  Like if I wanted to build the stout, I would find everything together.  In a perfect world I would not have to use adapters.  You have not mentioned what you can sell them for, but the adapters add around $15 to the price for each chassis after you get 2 and have them shipped from MoJo..  At that price on a 100 chassis order it wouldn't take long to pay for another program setup to make both chassis.  I am thinking it would be better and cheaper to make 2 versions as long as it is just a change in cutting and not overall size.


But what do I know?

[EL34]

I asked,
Andy does not want to make 2 different versions

They have to make them and put them in their catalog and a bunch on the shelf
Two different versions is more cost for them

I am stocking everything here, there's no getting adapters or chassis from Mojo

I am a Mojo dealer

I have public parts list on my site where you can add all the parts with one button

[sluckey]

Doug, have you considered selling blank chassis? That option appeals to me. That 12.5 x 6.5 x 2.5 is a very handy size for many small projects.

[EL34]

I'll have to ask Andy if he is interested in doing a small blank
But I'll wait till this project is done first

Andy makes a blank Aluminum chassis but it is 17 inches long
http://www.mojotone.com/amp-parts/chassis-generic-project/Undrilled-Aluminum-Chassis#.VAYIuPm2jpw

Undrilled Aluminum Chassis (Dimensions 17"L x 6 1/2"W x 2 1/2"H)

[Ed_Chambley]

I asked,
Andy does not want to make 2 different versions

They have to make them and put them in their catalog and a bunch on the shelf
Two different versions is more cost for them

I am stocking everything here, there's no getting adapters or chassis from Mojo

I am a Mojo dealer

I have public parts list on my site where you can add all the parts with one button

Oh, I thought you were saying just order the adapters from MoJo.  I got it now.


Too bad they cannot make a punch out like an electrical box, but I would guess they are not stamping the chassis.

[EL34]

Too bad they cannot make a punch out like an electrical box, but I would guess they are not stamping the chassis

No, this is real precise stuff, no punching

.09 inch thick aluminum cut on a laser machine

[EL34]

Doug, have you considered selling blank chassis? That option appeals to me. That 12.5 x 6.5 x 2.5 is a very handy size for many small projects.

Steve,
If I can get Andy to bend a few of these without any holes, do you want one?
BTW, they are 12 x 6.5 x 2.5

I noticed you typed 12.5"

[sluckey]

I noticed you types 12.5"

That was a brain fart. I meant 12".

I don't currently have a need but thought while you're on a roll I'd ask. It would be great to have a source for blank chassis, maybe even an assortment of sizes. That 12" chassis is a very nice size for a lot of small projects. If I needed a 12" blank and you had one, then I'd buy it, rather than have to go to you know who! 

[drew]

You know, if you were to make slight changes to the overall dimensions, and make the mounting flanges folded inward instead of outward, this chassis could be a perfect fit for an Epiphone Valve Jr. cabinet.  Epi sold a lot of those things; the cabs were good quality (plywood, not particle board); and I bet a lot of them are sitting around in closets, basements, etc., their owners having either lost interest in them, or ruined them trying mod the circuit boards. 

[EL34]

I'll ask Andy tomorrow if I can get some blanks with no holes
I don't see a problem with that, but you never know

I don't have a final price yet on the drilled chassis
Andy has to take all my CAD drawings and figure all that out

Just as an example, Mojo has two versions of their 18 watt chassis
The 17 inch long 18 watt chassis has a drilled and non drilled version
The non drilled cost me $16 less that the drilled, so I expect the non drilled Stout Chassis to be way cheaper


Drew, There is no room to bend the flanges to the inside
Plus if you use a rivet nut on the inside, it has height also
If this was a longer chassis, then there would probably be room enough to do that
Mojo bends the flanges out on all their aluminum chassis and so I am sticking with what they are used to doing

[Willabe]

Yes, I bought a couple of their 'blank' chassis' and their very good, BUT !!!! What I don't understand is why they didn't cut holes for square cage nuts (Marshall style) or have modern 'press nuts' installed.


                 Brad     

[DummyLoad]

maybe use tinnerman U-nuts?


 http://www.aircraftspruce.com/catalog/hapages/clipnut.php




--pete

[EL34]

I'll have to ask Andy how they secure their chassis that have the wings bent out

[macula56]

these look great so far. i'm interested for sure.

[lego4040]

  Wow Doug, that is sweet. You answered on of my future questions about not using the tube rectifier from that picture.  I need to start my thread later about building this

[EL34]

I noticed you types 12.5"
That was a brain fart. I meant 12".



Just wanted to make sure you had enough room inside :)

[EL34]

Mojo just uses #10 bolts and nuts on this style chassis

Andy had a point about the Marshall type cage nuts
You hardly ever see a Marshall chassis with all four still in place

I found these 1/4-20 thread clip on nuts that are fairly reasonable in price

[EL34]

Found these and they are even more reasonably priced

I ordered a bag of these to check them out
They are 10-24 thread
A Truss head bolt and these nuts should do the trick

[DummyLoad]

1/4"-20tpi would be my choice. maybe stock both?


--pete

[PRR]

> maybe use tinnerman U-nuts?
 http://www.aircraftspruce.com/catalog/hapages/clipnut.php
 
Thank you thank you thank you ! ! !
 
I've been stupid. I've known Aircraft Spruce for decades.

But when I needed sturdy clip-nuts for a chassis mounting some years back, I didn't think to look there. Great stuff. Much more trustworthy than the junque at Home Despot.

AND... my tractor has two throttle controls. It really needs three, and they should work better. I should have a hand throttle near the backhoe controls, which is out-of-reach of the main hand throttle.

Being near the sea, I went shopping for power boat levers. Ouch! Way over-priced.

Aircraft Spruce has a $20 job which may do me; if not for the big tractor, maybe the lawn tractor.

Then they have robust hand throttles $50-$90.

Also the good vernier lock knobs, which were an option on my machine, but the price has always been intimidating ($70-150). At least at Aircraft Spruce I know they are not junk, as I suspect for some of the low-price eBay offers.

[kagliostro]

Have you never think to use deformable threaded nuts

they require a simply round hole ad exist also in steel and aluminium or an anti vibration rubber version








https://shop.berner.eu/berner/it/category/957933/Bulloneria/Rivetti/Inserti+filettati


K

[DummyLoad]

Thank you thank you thank you ! ! !

YMW.

I've been stupid.

simply not possible!   

your AG-7 should ship tomorrow, friday at the latest. looking for a suitable carton so that it survives the journey...



approximately how long after your design acceptance do you expect to have these in stock doug?

more out of curiosity: what are the dimensions of stout board mounting centers?

looking forward to building a 6V6/6K6 version.

--pete

[EL34]

approximately how long after your design acceptance do you expect to have these in stock doug?
more out of curiosity: what are the dimensions of stout board mounting centers?
looking forward to building a 6V6/6K6 version.
--pete

Not sure yet Pete
Andy is going over my CAD drawings right now
Hopefully I may see one within the next couple weeks


The stout board board size and other is listed on this page
http://hoffmanamps.com/MyStore/catalog/TurretBoard.htm

There are no mounting holes, you put them where you want them


One in each corner should be fine for the Stout board

[EL34]

1/4"-20tpi would be my choice. maybe stock both?
--pete

10-24 should be fine for this small chassis

I ordered a small bag of 1/4-20 also to check them out

One thing you have to take into consideration is how far is it from the center of the hole to the inside of the bend
Too large and it will hand out in the breeze

[macula56]

Some new drawings with some changes

I added another set of OT mounting holes that will accept the 022905 Deluxe OT

My idea for using individual block off plates
I modified the chassis holes in the drawing below to have cutouts so that the 9 pin mounting hardware can fit through the 8 pin socket holes
The adapter has extensions so you can bolt the 9 pin socket in place with #4 screws and #4 keps nuts
I may be able to make those extensions a bit small and use #4 self tapping screws to mount the 9 pin sockets
The small diameter ring around the outside of the socket drops down into the 8 pin hole on the chassis

I made an adapter on my 3D printer this morning and mounted a 9 pin socket into it
I think this idea may work fine
I am sure Mojo would have no problems cutting the adapter in two separate pieces on their water jet or their laser cutting machines

 
Are you going to make these available by chance? I could use a few of these for sure.

[EL34]

Are you going to make these available by chance? I could use a few of these for sure.

No, I drew up all the CAD plans over a weeks time and gave them to the manufacturer but told them to throw them all away 

JK, see the post above

[lego4040]

5 bucks a piece for those adapters at Mojo but they do look well made.

I pay way less for them
Not sure If I will stock those or make my own


Whatever happens, I will have adapters to go with the chassis

[TubeGeek]

Have you never think to use deformable threaded nuts

they require a simply round hole ad exist also in steel and aluminium or an anti vibration rubber version








https://shop.berner.eu/berner/it/category/957933/Bulloneria/Rivetti/Inserti+filettati


K

This is what I am using lately and they work great!  You can see them installed on my latest project here...

[EL34]

This is what I am using lately and they work great!  You can see them installed on my latest project here...

They look nice, I'll look into them


They are called rivet Nuts
How are you guys setting them?
If I sold them, I can't expect people to buy a special tool

[EL34]

I got the 10-24 and 1/4-20 threaded clip nuts


The 10-24 may work ok
The 1/4-20 is a bit large to fit on the 5/8" wide flange of the chassis


I will get some rivet nuts and see how they work

[TubeGeek]

The rivet nuts do require an additional tool to install.  That may not be acceptable for you as you mentioned.  I bought a kit that included the tool and a couple hundred rivet nuts for $40.

[DummyLoad]

clip nuts can be replaced if stripped out. rivet nuts are a medieval technique replacement if stripped out... rivet nuts don't slide around though. just don't strip out the rivet nuts.


--pete

[Willabe]

Call me crazy, I'm like'in the look of those rivet nuts, but most of your customers wont need or want to buy the tool to set them with for a few builds.

Why should they strip out Pete?  There's more threads in the rivet nuts then the clips. Not using a torque wrench on them to tighten them down.     


                    Brad       

[DummyLoad]

http://www.afi.cc/contentonly.aspx?file=images/vendors/Tinnerman.pdf


if you're still considering 1/4-20 bolts and a U-nut - follow the above link - pg. 19, P/N 33945-1420 looks like the X & C dimensions will fit the 5/8" chassis lip.


https://estore.dbroberts.com/search_esb.asp?p=C33945-1420-4


url above shows to have 7500 in stock.


--pete

[DummyLoad]

Call me crazy, I'm like'in the look of those rivet nuts, but most of your customers wont need or want to buy the tool to set them with for a few builds.

Why should they strip out Pete?  There's more threads in the rivet nuts then the clips. Not using a torque wrench on them to tighten them down.     


                    Brad   

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


--pete

[kagliostro]

I build a tool for rivet nuts similar to this







but to install only few you really don't need a dedicated tool







K

[EL34]

Yeah, you do not need a special tool for rivet nuts as I figured out on you tube videos
I can contract the nut with an air tool fairly easily

I ordered some 10-24 thread rivet nuts to experiment with
10-24 is good enough for a small chassis like this
Steel rivet nuts that is
I understand aluminum rivet nuts may be way easier to strip and are more expensive

[kagliostro]

Doug how many mm are 10-24 ?

4mm diameter are easy to strip, 5mm are a bit less, using a modified standard riveter like this build by my friend


https://www.youtube.com/watch?feature=player_embedded&v=-GFsllloy9w


6mm you can strip easy the way I posted in the previous post and I use only steel rivet nuts

K