Member postings for David Jupp

Typically it is all to easy to overlook something in your own work (not that I'm suggesting you have) - that is the main reason for independent verification of designs.

May be worth noting that in industrial pressure equipment practice, the Design Verification Engineer and the Inspector are likely to different individuals with quite different qualifications/experience.

A Design Verification Engineer can check that the Designer has used a sensible approach or complied with a recognised code. The Inspector will check that the finished item matches the (verified) design. I would not necessarily expect either to be competent to do the job of the other.

Be aware that invertor drives are prone to tripping standard RCD devices - in industry 'delayed action' RCDs are used to avoid this. Your problem might not be realted to incompatibility between motor and invertor.

Edited By David Jupp on 23/02/2013 19:51:46

Any 3D CAD package that supports assemblies will easily handle linkages and interferences - gears are much less commonly supported, but may be able to be 'fiddled', depending upon exactly what you want to check for.

If just checking a basic concept, rather than taking the design through to real parts, there have been packages that allow you to do this with 2D sketches - though I'm struggling to find anything on the web at present.

First I'll declare a bias - I have a connection with Mintronics (the major UK reseller of Alibre).

As Andrew mentioned, using 3D CAD is very different from 2D, and it can take a while to get used to it. Whatever system you look at, do work through any tutorials provided - I mean actually work through, not just watch. I also suggest you check out the on-line user forum for any system you consider - you'll get lots of free help from a good forum.

I believe there is good information on Mintronics and Alibre web sites about capabilities for each version of Alibre - but feel free to call if you have questions.

I suspect you will find free 3D CAD systems will fall into the 'disappointing limitations' box, but you don't have to spend a fortune to get pretty good functionality.

Bearing manufacturers web sites typically give information on fitting bearings - including housing / shaft dimensions.

In some cases you may want slightly different dimensions for each bearing (axial movement allowed at one bearing to allow for shaft thermal expansion).

If you accidentally cut too much material away, there are 'bearing fit' adhesives available that can save the day (widely used in industry beacuse quicker/cheaper than close tolerance machining).

If information like country of origin, industry, rough manufacture date is available - it may well be possible to make some intelligent assumptions on likely thread series, then with pitch gauges and calipers identify the specific thread. Of course if the thread is a 'special' or a particularly unusual one then the methods mentioned by others above will come into their own.

CE is not a standard - the CE mark is supposed to indicate that the equipment complies with all relevant EU Directives (low volatage, machinery, EMC,...). These typically relate to basic EU wide 'safety' requirements and are rarely anything to do with performance or capability of the equipment.

Edited By David Jupp on 20/01/2013 19:26:04

Donald,

Few standards (for anything) are compulsory in any legal sense - though of course if the manufacturer claims the product complies with a particular standard then it should do so. Being for hobby use doesn't make any difference.

There will be a HUGE difference in stiffness between scaffold tube and 2 3/4" steel tube (especially if you get ally scaffold tube). They didn't use a column of that diameter originally just for fun.

Was not suggesting work hardening as a method to use (it explains why so many drills get broken in stainless) - just pointing out that 300 series steels will not harden by quenching.

If you want to harden stainless, it has to be from the correct family - if it is strongly magnetic you have a good chance it is. If weakly magnetic it's probably only workhardened austenic steel so will not quench harden.

I can't see some of the posts becuase they are obsucred by the advertising (this seems to happen irregularly on this site) so apologies if this is off beam...

There are different types of stainless (ferritic, austenic & martensitic)

300 series are probably most common - these are austenitic, they work harden like crazy - but do not quench & temper

martensitic, can be quenched and tempered - think surgical blades

ferritic - I don't have much information to hand at present !

So some stainless grades can be quench hardened, but many can only be work hardened. You can sometimes (but not totally reliably) identify austentic steels as being non-magnetic (work hardening can tip them into being magnetic...).

I'd suggest that the surface temperature probably isn't as high as that if you can hold your hand in place. Maybe with glassware you 'get away with it' because glass is not a fantastic conductor of heat, with metal object I certainly would not want to put my hand on anything very much above 50 C.

All 300 series (1.4404 equivalent to 316L ) will work harden. 400 series have different microstructure, less prone to work hardening, but not as widely available (and could be hardened by heat treatment anyway)

Use tapping drills on the larger side, and use a tapping compound.

Yes - see my post earlier.

Alibre used to allow licence transfer/sale, but no longer do so.

3D files are an Alibre extension to STEP (which will import as STEP in some other CAD).

2D drawings derived from 3D are proprietary format (same as many other CAD systems).

There is a free viewer availble for Alibre as mentioned earlier (but this has to be provided via an existing user - you can't just browse to it on Alibre's web site).

Have PM'd you a link.

In addition to the free 30 day trial of Alibre (Professional), any current Alibre user can provide a link which will let you register for a free Alibre viewer - this is the standard Alibre software with content creation capabilities disabled.

A while back Alibre used to allow transfer of licence onward from the original buyer - the EULA was altered and now sellng/transferring the licence is not permitted.