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Member postings for David Jupp

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

Thread: CH Motorised Valve Radio Interference
01/09/2019 12:29:11

I have had a tank stat that started to 'chatter' rather than switch off cleanly. The symptoms were that the pump would cycle rapidly several times at end of water heating. I initially thought issue must be the diverter valve, but no. I bought a new tank stat (different brand, as the problem one wasn't old). Fitting new stat solved the issue.

Not suggesting that is your issue, but tank stats can degrade in odd ways - so don't rule it out as a possible source of problems.

Thread: Current leakage om CNC
24/08/2019 17:26:19

Make sure the metallic parts are earthed (as required by IEEE wiring regs) ?

Thread: Big end lubrication
17/08/2019 10:10:47

Perhaps, but changing how the shaft is driven will probably move where the 'wedge' in the oil film in main bearing is positioned, so the experiment may not replicate reality.

Worst case would be if the maximum pressure generation from the 'wedge' was to coincide with the inlet from drip feeder.

16/08/2019 18:42:42

Hydrodynamic action in the oil of the main bearing will generate some pressure, presumably enough to push the oil into the hole for part of the revolution.

Thread: Boiler testers and material verification
07/08/2019 17:21:33

It is simple enough to follow the principles of traceability if you choose to. Nobody said you have to have ISO 9000.

Commercial vessel builders can manage without ISO 9000 quality systems for even very high level pressure systems - just have inspection in place of an approved quality system. That doesn't sound so far from working with your club inspector and knowing what he/she expects to see.

07/08/2019 13:00:36

The Mill Certificate is for a particular 'lot' of material, the material should be marked with the 'lot' identifier in some way (printed or stamped typically). When material is cut, the identifier should be transferred to both sides of the cut, before cutting. Where that isn't practical, material isolation as part of a quality system and record trail can be an acceptable alternative.

It isn't uncommon in industry to see material scrapped if either certificate or the marking on the material can't be found - as it is no longer possible to guarantee that the material is what it should be.

Thread: Laser cut plates
01/08/2019 14:43:28
Posted by ega on 01/08/2019 11:27:13:

Is there some way a laser cutter can do a dummy run to check?

Kind of; the g-code prepared to drive the machine can be plotted in a simulation program (many cnc controllers will plot the toolpath on screen anyway before starting, which can give a quick check). If using a simulator program, it has to be set up to mimic the controller being used (they vary in the fine detail). And of course an on-screen 'check' is only useful if the person looking at the screen knows what it should look like...

Thread: 3 phase - radio puzzle
30/07/2019 16:53:57

Businesses that sell VFDs often also sell suitable filters and should be able to advise.

30/07/2019 12:09:48

Could just as easily be conducted RFI back into the mains - in fact that is more likely given Ron's previous comments.

30/07/2019 11:08:38

Some VFDs have built in RFI filters, but these are typically only rated for 'industrial use' (where there might be more tolerance of some noise on the mains). Some of these filters can be switched out of circuit !

If you fit an input filter, it should be on the metal backplane that the VFD is mounted to for best performance (I've seen them located using Velcro strips !).

Earth connections and screen connections (not the same thing) are important. Screen on power connections should be bonded directly to the metal backplane.

Metal cabinet door should be bonded to cabinet body/backplane.

There is lots of good information on line - also lots of people contradicting that good advice. The installation manual for the specific VFD can often be a very good source of advice.

Thread: Learning CAD with Alibre Atom3D
23/07/2019 19:00:16

OK - a bug was recently discovered in the auto-update code in the product (it fails to correctly check your maintenance expiry date, very embarrassing !). Unfortunately this can't be fixed unless you update to the just released 2019.0 release.

If you purchased as a one off, the best thing to do is to disable the 'check for updates' option, so you don't get offered the 'update' that you aren't entitled to.

If you are stuck without access to the software as a result of this issue, contact Alibre support or your reseller (even without purchasing updates you will be assisted if the software doesn't run for you).

Basically you need to uninstall the new version and re-install the previous version - if you don't have the previous installer available, support/reseller can assist.

16/07/2019 08:59:44

I tried saving a file from FreeCAD - Alibre won't open it. I'm very puzzled as to how Ivan achieved what he describes.

15/07/2019 17:17:30


I'm not aware how Atom3D could offer that format. Can you share a screenshot showing this, and a description of how you reached that...? Seems like there may be something very odd with your installation. PM me if you'd prefer.

Thread: Universal T milling machine from Chester : Issue with Starting
10/07/2019 09:33:53

If your electrical knowledge is weak - I suggest you stop and get help from somebody that knows what they are doing.

Thread: Gear Measuring
30/06/2019 09:11:59

In 1990 OilDrive was acquired by Dinamic Oil - might be worth contact Dinamic Oil via the web site


Thread: Removing Broken Tap
28/06/2019 08:33:54

Colin - a bit late I know, but looks like 304L aka 1.4307 aka X2 CrNi 18-9 though none of the specs will be exact equivalents for each other.

Thread: Is CAD for Me?
27/06/2019 13:07:42

Nigel - you can use Atom3D as a Viewer if you wish (without a licence) - but note you'll have to follow the instructions previously linked to remove the reference to the 6 month trial to unlock that possibility. Obviously it's only useful as a viewer if you have some files to view - so there may not be any value to you.

26/06/2019 15:33:25

Nigel - if you wish to re-install Atom3D so that you can then uninstall it correctly, you can download the installer from


Thread: Learning CAD with Alibre Atom3D
25/06/2019 15:18:38
Posted by Nigel Graham 2 on 25/06/2019 14:54:12:

I wondered if David George's difficulty was due to Alibre registering the PC, so refusing to work on a second computer - a copyright protection move. I recall seeing similar happen elsewhere.

NO Nigel - David had released his purchased licence from his Desktop computer (so he could use it on laptop). BUT the expired trial licence was still installed on laptop. Because the 6 month trial is a 'special' it is managed differently from a standard 30 day trial, it therefore requires some intervention to remove it after expiry (as explained in the article I linked to) - slightly annoying no doubt, but a small inconvenience in exchange for the 6 month trial period. After removing the trial licence, David should be able to use his permanent licence on the laptop, and he'll be able to switch the activation between computers as needed.

Please try not to spread confusion by speculating on matters that you don't have knowledge of. By all means ask if you'd like to know more about how licensing (or anything else) works.

For information - uninstalling Alibre leaves the licence file behind on the computer (that makes updates simpler). The server at the licensing provider also keeps a record of the computer ID. A 'User Profile' is also not removed by a normal uninstall - the actual program files themselves are removed by uninstalling.

25/06/2019 10:32:02

Answered in this article


Whether it was an extended trial, an ordinary trial or something else - the same /bat file will remove the local licence files which allows you to re-start the activation process.   If still having difficulties contact reseller or Alibre support.

Edited By David Jupp on 25/06/2019 10:36:07

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