Member postings for David Jupp

Gerry - I've heard of Vespel, but have zero experience of it.

I also seem to recall that PTFE gives lower friction if there is at least some moisture (humidity) around - strange given that it was allegedly developed for the space programme...

I seem to recall from University materials classes that for PTFE friction increases when direction of movement changes, so it isn't as good as you'd expect in oscillating systems. If movement is always in same direction friction remains low - almost as if there is a 'nap' on the surface that has to brushed into place by initial movement.

Nigel,

Andrew's example is in Alibre Design Expert (big brother to Atom3D), I don't recognise the software that Nicholas was using. In Alibre there are 'Boss' (add) and 'Cut' versions of all major tools, other systems I've looked at are similar in that respect.

Two points -

1. yes there are differences between systems, even those that work in a broadly similar way. Generally the concepts will apply across many systems, but points of detail may require slight adjustments to the methods. Tools may have different names too.

2. there are generally many different approaches that can be used to model any particular part. There is no 'right', 'wrong', or 'best' approach - though some might have pitfalls.

Nigel - be careful using STL files to transfer designs between systems.

STL is not a CAD format, but was developed for 3D printing. It represents the design as many triangular facets, so it ends up being 'not quite' what was originally modelled. Some precision will be lost, and many CAD systems can't usefully edit STL.

If available STEP (or STP) , IGES, or others should give more robust results.

As mentioned in a previous thread on similar subject, it really does help with learning 3D CAD if you can get some personal tuition. It isn't always obvious which aspects of using CAD will cause the problems/frustrations - if in the same room as a tutor it's so much easier to ask a question, and it should be obvious to the tutor if anyone is struggling.

Videos can be good for learning specific operations, but can so easily gloss over or miss out the underlying basics - perhaps because it's 'obvious' to one who already knows. Videos are brilliant as a refresher for seldom used functions.

The major frustrations can be around finding how to access a particular function, or what input is expected, even what is the name of the function that I need, or how do I go back and edit the feature I just created (at the wrong size)... I also find routine Windows usage (not specific to CAD) can be as much of a block as the particular software.

As for time to learn, I used to run 2 day basic courses in Alibre Design. The course started with really simple stuff, it had a structure so that most of the main modules of the software were covered. Never more than 6 students in the class, so there was plenty of time to deal with questions. On a one to one basis, the material could probably be covered faster. The 2 day course aimed to get users from zero 3D experience to being comfortable working with the software. It gave students sufficient skills and knowledge to progress their own design work, it didn't by any means turn them into experts. An important point covered was how to get help in the future.

So if you are struggling to get started, I'd suggest try to get some time with somebody (patient) who is already familiar with the software you are trying to learn. Being in front of the same computer is best, but a web conference with screen share can work OK in shorter sessions.

These days most demos, or training on specific CAD functions that I do, use web conference (on cost and time grounds). A colleague (who does more design work than me) still runs the 2 day in-person courses - location and price are typically problematic for non-business users.

Alibre is certainly designed around use with a mouse.

Users that have problems with mouse have used for example combination of trackball and a 3D controller. The 3D controller can be good for zoom/pan/rotate (and offloads those functions from the mouse), trackball (or mouse) is good for precise selection/positioning.

There will be a need to enter numbers - some have used a separate number keypad if main keyboard isn't good. A good on screen numpad emulator might be another option for use with touch screen.

That's potentially quite a few devices plugged in.

Hopefully a shop selling touch screen monitor would let you take in your own laptop to try out how the software and screen play together.

David - user feedback on Alibre with touch screen is that the touch screen doesn't work very well at all (I suspect that is true of many CAD systems). Alibre may cope better than some as in sketch mode figures are placed by click, release, move to next location click, release (mouse button is not held down whilst placing line, rectangle, circle...).

A mouse will be essential. For BT mouse double check if it can recognise using L+R buttons at the same time (many BT mice can't). Alibre does allow re-designation of mouse buttons, the default uses L+R buttons for rotate workspace.

Suggest taking a free trial of Alibre to check how it behaves with your proposed hardware.

The Alibre file format is an extension of STEP. I'm told, but have not seen that some CAD systems will open Alibre files if extension is changed to STEP or STP (attempt at your own risk).

The extended trial for Atom3D was done using special licence keys - one side effect is that the software just stops working after the trial period - the usual free trial will offer 'viewer' mode after trial expiration.

You can work around around that as detailed in this Help article

If you have just a few files from Atom3D, ask nicely and maybe somebody with a licence, or running a current trial would open your files and export them.

As others have pointed out, a 'quick and dirty' one off use model may be done a little differently to a model that will have the key dimensions re-set multiple times to produce variations on a theme (without throwing errors, or disrupting the topology).

Both have their place - there is no single 'correct' answer.

But there are many ways to produce that in all 3D CAD packages - there is no 'preferred method' for each CAD package, only preferred method of the person driving the system (and the limits of his/her knowledge of the system being used).

Personally I might even tackle that slightly differently each time I try, as no one method jumps out at me as being simpler, faster, or more versatile.

Could use revolutions, or Extrudes, or a mixture. Could do it all as additive, or could do some subtraction.

I presume the 'pie slice shaped' hollows were omitted to keep things simple.

Edited By David Jupp on 11/04/2022 14:44:50

Jason,

Alibre Atom3D does have the Tracing Image function. It is in all levels of Alibre software.

Regarding connection of cable screens to ground, and on grounding of all items - I suggest you follow recommendations of the VFD manufacturer. Whether to ground one or both ends of the cable screen will get you at least 3 different opinions...

Quality of the VFD/motor installation may be a factor.

To work well, input filter should be mounted on same metal backplane that the inverter is mounted on.

A filter may not fix things if there are other issues with the installation.

The sleeve dips into water and forms a seal - more compact than a 'U' bend and can be cleaned by removing the sleeve.

Edited By JasonB on 21/02/2022 18:34:07

3D metal printing is another possible route to 'castings' of very high quality - perhaps requiring minimal finish machining of sliding surfaces.

Whilst laser or electron beam systems are still very expensive, extrusion based systems are significantly cheaper and give pretty good accuracy, if not quite as flexible regarding final part geometry.

All the different options have pros and cons. There is no single 'one size fits all' approach.

Is there a ball in the hole under the flat ended screw? That's sometimes done as a cheap option that is tolerant of the fluid port not being quite concentric with the thread. If port is not concentric with thread, it's more difficult to produce either a 'needle' or a 'spline' tip on any replacement item to give finer control.

Depending upon origin/age of chuck, you may need a 1/4 W (also 5/16 BSF) spanner perhaps.

0.525" or 13.34mm AF

Emgee,

"I believe the reason for calling the VFD a component is because the units can be supplied without a keypad, this is common for commercial and industrial users, so cannot function without another part or means of control."

No - it's because the VFD is for incorporation into a 'machine' or system (see declaration below). Because the VFD on it's own can't actually 'do' anything useful, it has to be combined with other things (e.g. a motor). Lenze can't control that step (apart from some of the warnings that I didn't copy from the manual).

"If the unit is likely to cause EMC interference in residential areas it will surely do the same in an Industrial installation, I am surprised that Lenze appear to have opted out of any responsibility."

Lenze can't control how well or badly the VFD is installed, nor what it is connected to - cable type & length, glanding, enclosure type, earth bonding, all make a difference. It's up to the designer/installer to get that bit right, and perhaps actually test the completed system. That might depend a lot on where it will be operated.

Domestic equipment could end up anywhere, alongside all kinds of sensitive kit - so the EMC requirements have to assume a reasonable worst case.  So for domestic use additional filtering might be needed (as an example). 

Some VFDs include internal input filters, some don't (assuming the installer will add one that suits the application).  In one project I did using a small i510 the added 'medical' input filter was almost as large as the VFD itself.

From the Declaration of Conformity for the same product

• According to the EMC directive, the listed devices are not independently operable products. Compliance of the directive requires the correct installation of the product, the observance of specific installation notes and product documentation. This was tested on specific system configurations.

• These products are intended for installation in machines. Operation is prohibited until it has been determined that the machines in which these products are to be installed, conforms to the above mentioned EU Directive.

Edited By David Jupp on 01/01/2022 09:41:48

Edited By David Jupp on 01/01/2022 09:44:24

Nigel, from your description, it seems that using Boolean operations in TC to cut material away (rather than using cut operations) is a complication you could do without. I don't know what tools are available in TC, but others may be able to help with that.

One thing I would comment, having seen Jason's video, there is no single correct way to model anything. For example Jason uses patterns in his sketches a lot. If I were doing the same task, I would usually create (for example) one hole, then pattern the hole (that is the 3D feature) rather than pattern in the sketch. There are pros and cons to each - both produce the same result.

Ideally it would be great if experienced users of TC and SE would show you live how to produce something like your engine block. That would give you an idea of if one really is easier to use/learn than the other, or whether they are equally complex form your perspective. The exercise could include things like angled drillings, and you could ask questions throughout. As that would be a viewing exercise, your current PC should be able to cope (a headset or microphone & speakers would help enormously).

For information - a few lines taken from 'Application as directed' section of the safety instructions in the commissioning manual for Lenze i510 series VFD. There are other lines which I didn't copy, these ones seemed particularly relevant to some of the discussion points in this thread.

• The product serves as a component for the control of three-phase AC motors and servo motors.
• The product is not a household appliance, but is only designed as electrical equipment for commercial or professional use in terms of EN 61000−3−2.
• The product is exclusively suitable for installation in control cabinets or similarly closed operating areas.
• As the product may cause EMC interferences in residential areas, the operator is responsible for taking interference suppression measures.

For most brands of VFD the full documentation (including conformity declarations) are available on line, for those who wish to look further.

Edited By David Jupp on 31/12/2021 14:43:27

Edited By David Jupp on 31/12/2021 14:43:48