Replacement Knobs, Feet and Fittings for Test Equipment

[DaJMasta]

Yep, there are a few good free options for CAD software and while it will take a couple weeks to get a really good feel for manipulating things and remembering where all the right tools are and such.... it's not a process that's too bad to learn.  Especially if you're familiar with mechanical drawings and how those translate into physical parts, you basically start by making a drawing in a program an then expand it out into 3d space, but you can make a drawing of every major side and manipulate the 3d model to line up with it perfectly.  A bit time consuming to learn, but powerful and fairly intuitive if you're familiar with this kind of thing.

It is nice to have the printer yourself so you can test fit and make minor adjustments quickly, though.

[beanflying]

It is nice to have the printer yourself so you can test fit and make minor adjustments quickly, though.

Yep V3 Foot is a winner but there is still a tweak needed so V4 coming up. I want to reduce the width of the angled sections where the bail slides along to lock in position. At the standard width and on the genuine part the foot flexes a lot and is most likely why a lot of them failed. 0.8mm a side should do it. 

Second tweak for others wanting to make this I am going to drop the knurl nut from the design as 5mm is a bit of an odd one to keep and just under size the hole to 4.8mm for the 5mm lock screw. With PLA the screw will tap itself in even if you don't own a 5mm tap to do it nicely.

Underside of my 735A Transfer Standard. I will use my pair of genuine one on the rear of it and the 427A as they are under less stress.

Edit: Photo added still has clearance under the screw head even with the feet sitting in the slot of the 6632B fascia.

[bitseeker]

Awesome work, bean! The only narrow-body gear I have is a 3469B. Everything else is in the 7-3/4" enclosures. I've been fortunate to have gotten feet on all but one of them, but their longevity is certainly a concern with the tilting bail. So, I just leave them stacked.

[beanflying]

Just about got the two sorted out for others to play with. First of the 7 3/4" ones. My 419A need a bottom and side plates making for it so I will fire up the Laser for the sheet parts at this stage. Narrow 427A floor just to keep the bits in place.

Seems the alignment of the longer feet to bail is different by a touch so the foot needs to come forward by 1/16" so the bail sits more vertically? Tomorrow job 11pm, Beans are roasted and my Brain is scrambled.

[beanflying]

7 3/4" Case Hewlett Packard formerly push button foot to Suit Late 60's and 70's gear.

Sorted and fairly happy with the result. Included in the zip file is the Fusion Cad file and STL for the print. As discussed in the preceding few posts the design requires a 5x10mm (may be ok with longer but check) Button Head screw instead of the more complex rivet and spring original.

Print it as you see it in the STL on edge to ensure the clips have maximum strength. I got the best results using the following on an Ender Pro and sli3er PE.

0.12mm Layer height, 6 top, bottom and perimeters, 40% infill. It will need to be printed with supports and may take a tweak depending on your slicer and printer but I dropped the overhang threshold to 40 degrees (works ok with 0.12mm layer), no support for bridges and 3 interface layers to make separating the material minimal.

[bd139]

Looks excellent 

[beanflying]

4 1/8" Case Hewlett Packard formerly push button foot to Suit Late 60's and 70's gear.

Sorted and fairly happy with the result. Included in the zip file is the Fusion Cad file and STL for the print. As discussed in the preceding few posts the design requires a 5x10mm (may be ok with longer but check) Button Head screw instead of the more complex rivet and spring original.

Print it as you see it in the STL on edge to ensure the clips have maximum strength. I got the best results using the following on an Ender Pro and sli3er PE.

0.12mm Layer height, 6 top, bottom and perimeters, 40% infill. It will need to be printed with supports and may take a tweak depending on your slicer and printer but I dropped the overhang threshold to 40 degrees (works ok with 0.12mm layer), no support for bridges and 3 interface layers to make separating the material minimal.

[beanflying]

Tektronix 453 Rear Cable Wrap Feet.

I recently got one of these with a mixed bag of damaged rear feet. The bottom feet on the 453 will get the treatment in the next day or two. No idea what other Tek's this fits so let me know?

Same procedure as other Cad and the two STL's are in the Zip File. It would be easy to mod if you are missing the rear lugs and needed to use a longer bolt. instead of the stud and screw. The Cap fits into the stock base if that is all you need to make.

[PedroDaGr8]

7 3/4" Case Hewlett Packard formerly push button foot to Suit Late 60's and 70's gear.

Sorted and fairly happy with the result. Included in the zip file is the Fusion Cad file and STL for the print. As discussed in the preceding few posts the design requires a 5x10mm (may be ok with longer but check) Button Head screw instead of the more complex rivet and spring original.

Print it as you see it in the STL on edge to ensure the clips have maximum strength. I got the best results using the following on an Ender Pro and sli3er PE.

0.12mm Layer height, 6 top, bottom and perimeters, 40% infill. It will need to be printed with supports and may take a tweak depending on your slicer and printer but I dropped the overhang threshold to 40 degrees (works ok with 0.12mm layer), no support for bridges and 3 interface layers to make separating the material minimal.

This is AWESOME, these feet are literally impossible to find.

The HP part number for the shorter  5 1/8" foot was 5060-0727, while the part number for the wider 7 3/4" foot in cases was 5060-0728

[bitseeker]

Bean, you're just awesome at these. I will have to start calling you Dr. Bean, Test Equipment Podiatrist.

[beanflying]

Thanks Guys

Some are easy like the Tek Feet as you have one mechanical constraint to work around. The HP click in foot was a bit of a pain as it relies on several mechanical points at odd fine angles and tight tolerances for it to work. If you load up the Cad file you will get an idea. The lower feet are going to be a bit of a guess for shape but so long as it fits the hardware and the holes on the cart will be fine.

The nice bit is when it all works and you get to show off your morning glory 

[beanflying]

Tektronix 453 Lower Feet

As per the previous post the lower feet on mine needed replacing. I have treated these like a knurl nut used in some of my other 3D models and slightly squeeze fitted the inner Hex with a small step to make alignment easier.

Print is easy but keep it heavy at 6 layers and 40% infill. It will be fine at 0.2 but I went with 0.12mm layers again. Insertion temperature with the iron was 230C for PLA but you may need more or less depending on your material choice. Give it time to heat properly and only use moderate pressure, if it seems to high raise the Temp. Added a couple more shots to the preceeding post due to the 1Mb upload limit 

3 more to go 

[nfmax]

One wheel foot on my waggon HP1740A

@beanflying or others, there is one, last (just) intact foot on my HP1740A scope. I have taken some pictures, and made a few measurements - though as you can see the foot is not exactly in its original condition.

Overall length (as photo) 36.9 mm. The foot end of the foot is 9.5mm thick and 22.0 mm square, the hole for the screw head is 7.8 mm diameter and 23.7mm deep (to the surface of the washer, which didn't want to come out). The 'scope end of the foot is 21.2 mm square and 3.4 mm thick. The two flanges are each 2.1 mm thick. The spacings from the flat surface next the scope chassis to the more distant face of each flange are 11.7 mm & 20.9 mm.

As you can see there is a little 'pip' on the 'scope face of each flange to help retain the mains cable.

[nfmax]

A couple more pictures. If you need any further measurements, just ask!

[tautech]

I find it funny the 1740 uses a cord wrap foot when it's at all not needed as these scopes have an IEC socketed mains lead. 
Plus there's a wopping great leads pouch in which to store the mains cable.

A new 3DP design is a fine chance to improve on the foot HP shipped with these scopes.

[bd139]

Totally agree. It's even worse for us in the UK as the plug is so damn big there's nowhere to put it. Cue scope rocking on top of a mains plug.

Philips had the right idea on the PM33xx scopes as they added little plastic two/three pin holes in the rear of the case so you could plug the plug into the back of the scope to keep it out of the way. However they screwed up as the cord winder plastic broke off instantly the moment you wrapped the first cable around it or the cable was at the wrong length so you couldn't actually wind it around without it falling off

And if they did ever leave space for a right angled IEC socket it was almost 100% certain that the IEC lead you had pointed the wrong way and couldn't be inserted 

[beanflying]

Even my Korean Protek has thin cord wrap feet with an IEC so maybe a scope defacto standard over time and it gives the ability to float the scope easier?

I will have a look at drawing a clone for the 1740 et al if people are keen but given the short screw and thinner nature of them it is asking for them to shear off again. While it is most likely the plastic used that failed the chunkier one I designed is the more practical.

The recent Tek 453 I did was different in that it had a stud running nearly full depth and some of the main bits were still ok so I went clone instead of fatter and  practical mainly so I could just print the tops caps needed.

[tautech]

Even my Korean Protek has thin cord wrap feet with an IEC so maybe a scope defacto standard over time and it gives the ability to float the scope easier?

Yes I guess that was their thinking at the time however who'd want to float a scope at say 400V and with 35mm of foot length and adding speed bumps cord wrap ribs does effectively lessen any creepage risk but these days we don't have to go overboard due to the filaments we have for 3D printing compared to the hard rubbery foot HP originally used.
Last 1740 I had I made feet from hollowed out bits of wooden broom handle. 

[nfmax]

Totally agree. It's even worse for us in the UK as the plug is so damn big there's nowhere to put it. Cue scope rocking on top of a mains plug.

Philips had the right idea on the PM33xx scopes as they added little plastic two/three pin holes in the rear of the case so you could plug the plug into the back of the scope to keep it out of the way. However they screwed up as the cord winder plastic broke off instantly the moment you wrapped the first cable around it or the cable was at the wrong length so you couldn't actually wind it around without it falling off

And if they did ever leave space for a right angled IEC socket it was almost 100% certain that the IEC lead you had pointed the wrong way and couldn't be inserted 

 I have a Hameg HM605 which has the moulded-in 13A dummy socket, too. Those scopes are actually very nice, and almost completely repairable - no custom ICs or hybrids.

[bd139]

I've used but never actually owned a Hameg scope. Might have to sort that out

They also have the component tester (curve tracer) which is rather useful too 

[TERRA Operative]

I got bored last night so I came up with my own version of the rear stand-offs for HP gear.
Someone might find it useful maybe..

https://www.thingiverse.com/thing:3606417


BTW, does anyone know what the thread size is for the screws for these things? I'm having trouble matching it up to anything..

[beanflying]

Depending on the Era HP/Agilent have used a mix of US threads and Metric. Given the era for those rear feet I would take a stab at UNC or UNF depending. I brought a set of cheap pitch gauges to help me sort them out.

Metric and Imperial pitches https://www.aliexpress.com/item/Thread-Plug-Gage-Stainless-Steel-Metric-American-Screw-Pitch-60-and-55-Degree-Thread-Measuring-Gage/1000003164025.html?spm=a2g0s.9042311.0.0.755b4c4dhy9Pjc

Generally they follow a format of 4-40 8-32 or 6-24 describing the nominal diameter and TPI. 6-32  is fairly common and in about 3.5mm in metric and is also used fairly commonly on general enclosures too. More Reading

[DaJMasta]

Minor addition: Dust covers for an Anritsu OSLN50 O/S/L calibration tee:
https://www.thingiverse.com/thing:3615116

The normal N type male dust covers I had didn't fit, so I designed up one to print from flexible filament.  Doesn't fit too tight (may work in a rigid filament type) and keeps the dust out when you've got your antenna analyzer or VNA on the move.

[DaJMasta]

A few days later, another one:
Rear foot for a Sencore Powerite II PR570 variable isolation transformer - will probably fit other equipment from Sencore as well, there are a few things in this form factor.
https://www.thingiverse.com/thing:3624712

[beanflying]

Nice looking prints on the last one  I will get them added to the front index in a bit.

Getting sidetracked at present into playing with my little 40W Laser and some Acrylic Panels for my 419A project.