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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: Learning CAD with Alibre Atom3D
03/11/2019 09:35:13

For a quick method - Emgee's tip (which I had forgotten all about) is probably simplest.

For ease of future editing, Jason's suggestion to fully define the positions is a good one.

My earlier comment about using 3D pattern doesn't apply to the example you have shown.

02/11/2019 10:56:11

Alibre Atom3D is cut down from Alibre Design - mainly to simplify the interface and make it easier to learn. That does result in some functionality being lost, but it is also much less expensive than the Professional or Expert versions.

If you use the 3D feature pattern, rather than 2D sketch pattern to create your arrays (if I'm interpreting your words correctly), then repositioning the array is simple.

Thread: Unusual Pliers tool?
28/10/2019 16:30:15

SMC TK-1 or TK-2, RS amongst others sell them and have tube size details.

28/10/2019 16:12:39

It's a pipe cutter. SMC do a lot of stuff for pneumatics, a tool like this cuts the tube nice a squarely. The 2 rounds in the jaw will be for different sizes of tubing.

Thread: VFD Instructions
18/10/2019 14:25:32

Note that the 'understandability' of manuals supplied with VFDs does vary widely.

Some are poor translations or include poor use of English.

Some assume you have lots of technical knowledge, but don't give any basic guidance - or offer a huge wealth of settings and just confuse you.

One advantage of major brands is you can have access to e-mail or telephone based technical advice of a high standard included in the purchase price.

For any VFD with a brand and model number, you should be able to locate the manual on line and then decide if you could work from it.

Thread: Inverter reset?
12/10/2019 16:08:06

It is quite common (but not universal) to define fault reset to the same terminal as Start when configuring an inverter drive. Some might prefer a separate reset button.

Thread: Good practice for lathe circuit design
04/10/2019 14:53:54

On your last point - the E-Stop should stop anything that might cause harm to people, or cause damage to equipment.

On that basis it should power off the motor, and probably the ELS.

It's probably advantageous to leave lights and DRO powered during an E-stop event - those circuits aren't going to move anything, but should be fused, or have equivalent electrical protection.

If you progress to a VFD you might want to consider if injection braking with delayed power off would be preferable to a simple power off - though it is harder to provide this.

Low voltage lighting would be preferable to mains (hurts less when you poke a screwdriver through the lamp), lots of good LED lamps around these days.

Thread: PC problem #2
23/09/2019 13:33:21

Check for new firmware for the card. If you are managing card via Windows, try the utility that came with the card, if using the utility try doing it directly via Windows.

You might just be unlucky and have a card that doesn't 'play nicely' with your WiFi base station - in which case, try a different brand of card, one that uses a different chipset.

I once wasted half a day trying to get WiFi connection to a PC working - the fix was to change the card, then up and running in 2 minutes.

Also check for new firmware for the base station - though once I've had to roll back to previous firmware to maintain connections to a particular device.

Though built to a common standard - not all devices are completely interoperable!

Thread: Drawing
03/09/2019 11:47:47

Taking that a bit further.



So if stock is a square, or you have a square marked out.  Start in one corner - draw 2 lines at 15 degrees to sides of square, join the points where these 2 cross the other sides to make 3rd side of triangle..


Or set callipers/compasses to 3.106" ,  start from one corner of square, where compass arc crosses sides of square gives other 2 corners of triangle.

Edited By David Jupp on 03/09/2019 11:48:18

Edited By David Jupp on 03/09/2019 11:52:25

Thread: Pivot Steel - Machinability
01/09/2019 19:35:35

Interestingly a search for EN 4454 on the British Standards site, doesn't find any matches.

There is an Indian Standard IS 4454 Part 1 for Patented & Cold Drawn Spring Wire - could well be derived from an obsolete BS. BS re-cycle numbers, which can be very confusing.

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.

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