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 Service jig or stand
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 Return to top of page · Post #: 1 · Written at 9:09:54 AM on 12 June 2013.
Maven's avatar
 Location: Canberra, ACT
 Member since 23 August 2012
 Member #: 1208
 Postcount: 581

On the homepage of http://www.thebakeliteradio.com/ there is a historic illustration of a radio factory, where each chassis is fixed in a protective jig that enables it to be placed safely on a bench at any orientation as it goes through the factory.

Were these things common, and are they used at all by vintage hobbyists?

I'm thinking about making one up - maybe using PVC conduit or irrigation tubing that wouldn't have been available in the old days, and would provide insulation and some resilience.

The challenge would be to devise a mounting system that would hold a range of different chassis sizes while not obstructing access from any direction.

Maven


 
 Return to top of page · Post #: 2 · Written at 12:04:14 PM on 12 June 2013.
Scraps's avatar
 Location: Blue Mountains, NSW
 Member since 10 March 2013
 Member #: 1312
 Postcount: 401

Love the suit and tie under the dust jacket!

It looks like the chassis is tied on. You could make the width adjustable by making the bottom rails from two different size pipe, one that slides inside the other. Attaching the chassis securely would be the problem. I use a large flat piece of pine with multiple holes for adjustment with a variety of small, rubber tipped dowels for stands. Primitive but effective.

I've seen a fancy adjustable wooden cradle/stand that rotates on the horizontal axis on a USA website.

http://tinypic.com/view.php?pic=2566zxs&s=5.
http://tinypic.com/view.php?pic=29uvw3t&s=5.

Very nice but very expensive. Probably something one could knock up in a few hours with some "wooden timber" Smile and a router.


 
 Return to top of page · Post #: 3 · Written at 1:03:09 PM on 12 June 2013.
Redxm's avatar
 Location: Tamworth, NSW
 Member since 6 April 2012
 Member #: 1126
 Postcount: 401

My jig is this.

Get an appropriate sized piece of MDF. Say 60cm X 30cm.

Drill holes in a grid fashion, the more the better.

After holes are done, fit a piece of small ply to the bottom to cover holes. Then get a length of dowel to fit the holes and cut to various Lengths.

Then it's just a matter of placing dowels in appropriate holes so the chassis is supported.

Timber chassis stand
Timber chassis stand
Timber chassis stand
Timber chassis stand


 
 Return to top of page · Post #: 4 · Written at 1:22:56 PM on 12 June 2013.
Scraps's avatar
 Location: Blue Mountains, NSW
 Member since 10 March 2013
 Member #: 1312
 Postcount: 401

Exactly the same as mine, far better description though. You can't have too many holes on the base board, I set the depth gauge on the drill press so mine don't go all the way through. I was limited by the reach of the press so couldn't get all the way to the centre leaving a section without holes. So far not a problem but a really tiny compact chassis could be difficult. I used 8mm dowels with 6mm rubber chair tips so the chassis can't slip, they're a tight fit but eventually go on. I could only find 6mm or 10mm tips. 6mm dowel is too small and 10 too big. To get the dowel to fit snugly in the base board I drilled the holes slightly undersize and cut small slots in the end of each dowel, same idea as some pots use to keep the knobs on.


 
 Return to top of page · Post #: 5 · Written at 6:59:18 PM on 12 June 2013.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 4398

PVC conduit of a similar gauge to the metal frames pictured, whilst an ideal size, would not be strong enough for any bar the smallest radio chassis.

I would say those frames were made for a specific sized chassis with others being used for the larger console sets.

The idea itself is a good one though, nothing is worse than a valve breaking under the weight of a chassis or the chassis rolling around whilst one is trying to measure voltages across components.

I have often thought of a large arm, mounted to the wall behind the workbench with similar flexibility to one of those desk lamps with the magnifying glass built in but strong enough to hold a heavy chassis still. It would also require a clamp to suit various sizes that would grip the chassis like a crane grips a pallet of bricks.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
Brad.

A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 6 · Written at 7:34:54 PM on 12 June 2013.
Redxm's avatar
 Location: Tamworth, NSW
 Member since 6 April 2012
 Member #: 1126
 Postcount: 401

Ive just emailed Brad some pictures of my setup.
Its not perfect but has done all Ive ever needed it to.
As Brad indicated it needs to protect the valves and dial glass.
The pic shows a small portable chassis I had on hand, but it really needs a bit more thought to hold one this small.

When I built it, I had console chassis' in mind.

(sorry for poor/blurry pics, usual camera was flat)

ben


 
 Return to top of page · Post #: 7 · Written at 7:41:12 PM on 12 June 2013.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 4398

Photos uploaded.

When correctly used this is probably the most failsafe way of supporting a chassis.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
Brad.

A valve a day keeps the transistor away...

 
 Return to top of page · Post #: 8 · Written at 12:00:17 AM on 13 June 2013.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 4013

I don't do enough radios to warrant one on my bench, but if I did I'd favour a rotisserie style that I've seen in old photos of repair shops back in the day.



 
 Return to top of page · Post #: 9 · Written at 4:04:51 PM on 13 June 2013.
Maven's avatar
 Location: Canberra, ACT
 Member since 23 August 2012
 Member #: 1208
 Postcount: 581

The dowel-farms look simple and effective, but I suppose need to be re-built if changing the position or angle of the chassis - say to solder something deep in a corner of the rats nest.

Those wooden "rotisserie" stands in the photos linked by Scraps look really good and easy to adjust for size or angle. However from the glum looks of the vendors it seems they might be too expensive for your average backyard tinkerer (eg me).

I take Brad's point about PVC tubes maybe not being strong enough for a cube frame. I'll think a bit more about that. A combination of light steel and PVC, with rigid corner joints, might work. PVC right-angled extrusions such as used in panel fixing might be more rigid than tubes. We don't need much more strength than a normal cabinet would have, but we don't want wobbles either.

I have been reckoning on bolting the chassis to the jig using the same anchor points that would normally fix it to its cabinet. That would impart some rigidity. Time to sniff around a big hardware store...

Maven


 
 Return to top of page · Post #: 10 · Written at 10:32:49 PM on 13 June 2013.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 4013

Ha, I missed those links. Those units look pretty tidy and well-finished compared to what I have seen, but are the way to go I reckon.

The stands pictured are made to order by a fellow in Oklahoma:

FOR SALE: Radio Chassis Holders. These maintenance stands hold a chassis while work on it. Small stand - $37.50, and Brackets - $2.50 Plus Shipping. Large stand - $55.00 and brackets - $2.50 Plus Shipping. Contact Steve Strong at (405) 634-7547 or e-mail: Scstrong1.cox.net


 
 Return to top of page · Post #: 11 · Written at 5:25:16 PM on 14 June 2013.
Maven's avatar
 Location: Canberra, ACT
 Member since 23 August 2012
 Member #: 1208
 Postcount: 581

Well, I went ahead and built a servicing frame that turned out to be simpler than I expected.

I don't have a lot of bench space so I made a frame that is only slightly bigger than the chassis, but provides protection on all sides with the chassis resting at any angle. The frame itself weighs less than the bakelite cabinet.

PVC chassis jig for vintage radios


The two end hoops are made from 20mm rigid irrigation pipe sold in hardware places as "pressure pipe" for about $2.50 a metre. The 90degree corners are about $1.50 each. The hoops are fastened to the chassis with the original cabinet mounting bolts, accessed through the larger holes visible on the outer surface of the tubes.

PVC chassis jig for vintage radios


A piece of plywood bolted to both hoops across the front of the chassis provides all the lateral strength and stability you need, so the chassis can safely be stood on end if need be.

PVC chassis jig for vintage radios


It is simple enough to prop the frame at an intermediate angle if desired. Here I am using the gap in my Workmate bench, plus a length of wood.

The frame could be adjusted for different chassis types in different ways. You could make it large enough for your largest chassis, and have a range of holes in the base tubes for mounting, plus a range of bolt-holes in the plywood lateral piece for different widths.

So far, I have found that the hoops stay together purely by the friction in the corner pieces, like tinker-toy, even if I lift the assembly from the top with the chassis in it. So it would be simple to keep a range of tube lengths to reconfigure the hoop size.

For more security, the corners could be fixed to the tubes with push-through pins. Originally, I planned to glue those corners, but now I plan to leave them as they are. This will be more convenient for adjustment and also for storage. When not in use - take off the plywood lateral and the frame will store flat in three pieces.

Maven


 
 Return to top of page · Post #: 12 · Written at 9:27:39 AM on 26 June 2013.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 2747


 
 Return to top of page · Post #: 13 · Written at 9:30:41 AM on 26 June 2013.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 2747

Some HMV sets like Nippers & some Grams. show a lot of forward thinking.

They come with roll cages.

Marc


 
 Return to top of page · Post #: 14 · Written at 2:13:30 PM on 26 June 2013.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 4013

Nice work, Maven!


 
 Return to top of page · Post #: 15 · Written at 12:20:52 PM on 28 June 2013.
Maven's avatar
 Location: Canberra, ACT
 Member since 23 August 2012
 Member #: 1208
 Postcount: 581

I've been using this for a couple of weeks now, and it's a big improvement on the bench-balancing I was doing before.

For extra stability, I'm thinking of making an additional plywood brace to go across the top rear part of the cage. To make it easy to move or remove, I'll try attaching it with round spring clips - the type you use on a tool rack. When I do this, I'll post another photo.

Maven


 
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