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Member postings for Stuart Bridger

Here is a list of all the postings Stuart Bridger has made in our forums. Click on a thread name to jump to the thread.

Thread: Whitworth v UNC
17/11/2020 19:40:25

In the UK aircraft industry, unified threads were seen as the spawn of the devil. Purely due to the potential for mismatching resulting in dangerously reduced strength. All aircraft grade fasteners with unified threads had to be specifically marked with a symbol with three circles.


Edited By Stuart Bridger on 17/11/2020 19:48:02

Thread: Source of 1/2" Diameter Delrin
17/11/2020 18:33:30

I have always used Direct Plastics, but they only seem to stock metric sizes

Thread: Aluminium surface finish
17/11/2020 08:41:10

Turning?, Milling? Polishing?
Also what grade of aluminum?
When I was an apprentice we used to joke that you could get a good finish on "Dural" - Duralumin aircraft grade alloy with a blunt nail, it was so easy to machine.

Thread: Chipmaster variator
17/11/2020 08:12:05

There are a number of posts on the Practical Machinist Forum about variator strip and repair. As Pete says, adjustment should be the first step. If the variator is worn, spares may be very expensive and it is almost certainly cheaper (and easier) to replace with a VFD. Mine is a little noisy but has sweet spots, where it is easier on the ear, so it is staying as it is for now.

Thread: Calibrating Micrometers
12/11/2020 19:01:29

Excellent post from Howard, absolutely spot on.
When I was an apprentice at BAe Weybridge, I did a tour of the mechanical standards room, but no practical experience. I did however do a 3 month stint in the Electrical Standards Department. That was fully temperature and humidity controlled with a "room within a room" where the high precision work was carried out. Every meter on site was calibrated every six months and there were 100's of Avo's to get through. That was the routine stuff. The higher precision instruments needed much more specialised treatment. One rule I learned was that to calibrate something you need at least 10x the accuracy with the kit you are using to calibrate. All of course was traceable directly back to national standards.

Thread: What are these? My first post.
11/11/2020 09:49:41

Looks from the photo's that they are made from aluminum alloy? If so I wouldn't have thought that they would be durable enough for a gauge? I am thinking either apprentice test work or perhaps some form of sales samples.

Thread: M G Electrics (Colchester) suds pump wiring.
10/11/2020 19:58:20

Hi Jim,

That's exactly how my suds pump is wired. Motor run cap to give the third phase. Very easy way to run a low powered 3 phase motor off a single phase supply. No need to change. I would tidy up and leave as is. I think there is a terminal diagram under the cover of mine, but I'm not too enthused to poke about down the back of the lathe to dig it out.

Thread: Adjusting cross slide Colchester bantam lathe
10/11/2020 13:46:49


Assuming that the assembly is the same as the Chipmaster and you don't have a taper turning attachment installed. I think you have missed the lock nut that secures the screw to the handle. This goes through the centre of the big handwheel nut.


10/11/2020 11:18:07

Hi Terry,

Can you be a bit more specific. When you say only moves in one direction, does the handwheel turn in that direction and not move the slide, or is the handwheel locked as well? I don't have a Bantam, but a Chipmaster and I believe the slides are similar.

Thread: Tom Senior E type - fitting 3 axis DRO
08/11/2020 21:09:36

Nice work, very tidy installation

Thread: Huanyang VFD help please
08/11/2020 21:04:30

I have to ask why? A conventional pot would give a much more useful variable speed rather two fixed.

Thread: C0 Lathe Blowing Fuses. Control board short?
01/11/2020 19:30:06

No direct experience of this lathe, but my recommendation would be to check high powered active components first. I.e. diodes and transistors. Not sure if replacement components are easily available though. Not cheap but the complete PCB is available from Arc Euro. Probably the simplest option.

Thread: 1000 to make a Spitfire aircraft fuel tank gauge. Can it be done cheaper?
12/10/2020 20:38:52
Posted by Nicholas Wheeler 1 on 12/10/2020 20:27:05:

What do you think 'aircraft grade aluminium' is??

A much abused term!

Aircraft grade alloys will meet certain specifications and have traceability documentation verifying origin, conformance and batch.

12/10/2020 19:49:35

Most of the cost will be tied up in paperwork. Both getting approval for the replacement design with substitute materials for those no longer available and traceability documents for the new parts. A fuel gauge will be very much a safety critical part, so subject to the most stringent regulation.

Thread: What is a Good Second Steam Engine Model to Build?
11/10/2020 21:16:05

Check out Elmer's Engines plans. "Bar Stock" engines with varied complexity. I'm.working on the #29 mine engine as a follow up to a 10V. Albeit with a diversion via a Universal Pillar Tool to help with tapping.

Thread: Sky Broadband and Windows 10
08/10/2020 19:41:57

The host operating system should have no relevance to the broadband service.

Thread: High Temperature Air Source Heat Pumps for Domestic Heating
08/10/2020 19:33:38

The GSHP example seems a bit extreme. We installed a an IVT unit 13 years ago with panels a metre deep in the back garden. We have never experienced the permafrost effect and it has no effect on the lawn. I do keep an eye on the ground loop temperature and only one year has it been sustained below zero on the incoming side. We do supplement with a wood burner in the winter though.

Thread: Any experience of Sturdi Shaft repair sleeves?
06/10/2020 14:30:39

Thanks all, great feedback

06/10/2020 13:41:24

I tripped over the above and wondered if anyone has any experience?

The context is that my Chipmaster has a known issue of leaking oil from the clutch shaft. About 5 years ago I replaced the oil seals, but it never really fixed the issue. The leak has been getting progressively worse. I did notice at the time that the shaft one of the seals was fitted on had considerable wear. I couldn't do anything about it at the time and was just hoping that a new seal would improve the situation. The Sturdi product looks like an ideal solution to finally fix the issue at a sensible cost?

Thread: Chin Yu 4 jaw chuck
04/10/2020 22:11:44

M10 x 1.5 is definitely not standard. Although originally an American standard the D1 camlock is incorporated into the ISO standard 702-2. This specifies M10 x1 for the stud thread for D1-3.

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