Member postings for David Jupp

From limited searching of the catalogues of standard steel products that I get most information from, there doesn't seem to be any steel hexagonal hollow.

If anyone does manufacture such a product, it's likely to be a special.

I presume the Heating Engineer did check the accumulator in the combi boiler?

I once helped a friend who had mysterious fault on the heating - like yours would work OK if topped up, but when cooled down over night was showing low pressure and wouldn't light. I eventually realised the accumulator was completely full of water (no air) - I found this by checking the Schraeder fitting on the accumulator. It was fiddly, but not all that expensive to replace. I presume the internal diaphragm had split.

You may well have a system leak, but it could be worth checking the accumulator before you start ripping floors up.

The button method would be useful if the part was large/heavy, or if there were other reasons why it had to remain clamped firmly to the table throughout.

Some VFDs also offer DC injection braking to give more rapid stopping.

According to companies house, A&R Precision went into voluntary liquidation in July 2015.

It sounds as if you are planning to have a pressure hull - I wouldn't think a kayak would be much good for that (shape for one thing).

Amongst numerous other issues to consider - PVC can be brittle at low temperature.

If you are actually planning a propulsion device for a SCUBA diver, things may not be so tricky.

This project sounds rather like a life support system, so people may be cautious with giving any advice.

Maybe even consider a bench with downdraught airflow if you are doing this full time.

Alternate welding methods might reduce the need for dressing...?

The GA and detail drawings are produced from the 3D model with very little effort (the projections are automatic - as often are section views). The model inherently includes sizes (everything is typically modelled at full size) and the CAD system has measurement tools to allow easy checking of any resulting dimension. These sizes drive any dimensions that you choose to include in the 2D projections.

You can drag the viewing angle round, zoom in/out, hide parts or make them semi-transparent to 'get at' things.

Peter,

In addition to points made by others. 3D is great for checking interferences or clashes in assemblies at the design stage, or even checking movement of mechanisms. It will estimate part/assembly weight for you (if you enter correct material density). Changes tend to be easy - and the derived 2D views update automatically to reflect the change. You can also download lots of 3D content from the internet to incorporate into your designs - so for many bought in items, you don't have to spend time drawing them yourself.

Of course there is nothing wrong with using 2D only.

EDIT - I'd also add that (particularly with the use of shaded and isometric views) - 3D CAD can help a lot in conveying your design ideas to those who either aren't familiar with 2D drafting, or just have trouble visualising the finished item.

You will get much faster with practice.

Edited By David Jupp on 22/08/2015 14:52:38

Ultrasonic leak detectors are surprisingly effective in noisy environments, the 'noise' is typically in a very different frequency range from that which leaks give rise to.

Rather more expensive - you can now buy clamp on ultrasonic flow meters that can measure gas flow rates.

A simple device that seems to offer what you ask for would be a Rotameter - a 'float' rises up a graduated tube , more flow, the 'float' lifts further up the tube. A quick search on Rotameter should show some options.

There are many options. I'd suggest that you find one that is either used by somebody who can help you get started, or one which has lots of training material available.

The cloud based options mentioned in the other thread are certainly great value for the hobbyist.

In my opinion there are huge advantages to 3D CAD over purely 2D.

Ensure your DXF or DWG drawing file is generated as if on a 'blank sheet' - any borders or title blocks will only have to be removed. Create the drawing file at full size (1:1 scale).

Check with the contractor - including one single dimension to allow verification of scale after import to their system may be a good idea; otherwise don't include any dimension annotation.

Once you have the drawing in your software, creating a PDF should be easy from any software - just print to any one of the many PDF 'virtual printers' that are available (many of them free).  You may want more dimensions showing on your PDF print - that is where 'layers' are helpful - you can turn visibility on or off as required.

Edited By David Jupp on 10/08/2015 14:27:38

Ah - have just updated my Irfanview - you should have un-checked the Amazon one button option during the install (or the sub options).

Neil - I've never had issues with irfanview adding unwanted software - so sorry about that. Maybe things have changed since my last download. I always download direct from the author's site.

Irfanview - a great little program.

Peter

The UK Autodesk site is not as clear as it might be about Fusion360, the US site is somewhat clearer. Have a good hunt around, some pages don't seem to have been updated to reflect recent changes of policy.

I've purchased from Associated Spring. They have on-line ordering and the minimum order charge is quite modest, though may still seem expensive if you only need a very small number of springs.

You should be able to verify dimensions on any supplier site using the tables of sizes.

Edited By David Jupp on 26/07/2015 08:51:09

Unlike steel, where there is a 'knee' in the fatigue curve, it is not possible to totally design out fatigue failure from aluminium items subject to cyclic loading - no matter how low the stresses are. Hence the time limit on service life mentioned above.

S155 is not a stainless steel - it is an aerospace spec alloy steel, offering very high strength.

EN 24 & EN26 are not high alloy steels - they are low alloy steels.

BS S series steel are typically expensive because of the tighter production specification and extra testing demanded for aerospace certification. S155 is vacuum re-melted (extra cost), I'm not familiar with the specific grade - the high Silicon content is rather unusual. At least some S series steels are based upon steels from BS970, so there may be a less expensive alternative for non-critical applications. Perhaps another member is aware of any close equivalent grade.

When considering such high strength levels, you should also look at toughness & fatigue properties of any alternative considered.

Edited By David Jupp on 15/07/2015 07:49:42

BIOX would seem to be a good candidate. Enzyme based, degreases, also removes scale. Non flammable. Unlike detergents, you shouldn't be washing bubbles out for ever afterwards.