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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: 3D Printing for Lost Wax Casting
14/04/2018 10:29:55

For high quality finish, there are 3D printable waxes designed especially for lost wax casting. Not sure if such things are available for 'home' printers. It might be worth checking what the bureau services can provide.

Edited By Neil Wyatt on 17/04/2018 13:52:27

Thread: Problem With Corrosion Of Stainless Steel
10/03/2018 13:57:45

From a supplier web site

With its higher sulphur content 416 stainless steel has lower corrosion resistance to that of 410 stainless and all other 400 series stainless steel grades. It provides optimum corrosion resistance in the hardened and tempered condition. Allowing oxygen to circulate freely on the surface 416 stainless steel will form an oxide film which protects the surface. Keeping the surface free of scale and foreign particles improves corrosion resistance, finished components should be passivated.

Thread: VFD problem
01/02/2018 17:11:20

Maybe try removing power for a few minutes then re-connecting. It's a long shot, but low cost to try. It's usually possible to find manuals on-line somewhere if you have make and model number.

Thread: Live Steam boiler legality and Boilermaker Questions
23/01/2018 14:59:19

If you refer to Chart 5 - Steam Generators, of PED that shows no pressure limit if V < 2 litres.

There is a special exception for pressure cookers, which are treated more strictly.

The lowest values for product PS.V is given in Chart 1 (for nasty gases) and is 25 bar.litres

I agree with Nigel, that some of the boundaries on the charts (including Chart 5) are set by the product PS.V

If an any doubt refer to the Charts yourself


Technically those notes are outdated, though easier to follow than the full text of the directive. The charts included are still correct, even for the updated 2014 version of the directive (effective 2016).

23/01/2018 08:34:42

Requirement for CE marking depends on size. If volume is less than 2 litres the steam generator would fall into 'Sound Engineering Practice' in which case it must NOT be CE marked.

Above 2 litres CE marking is required if the item is 'placed on the market'.

Information on the UK implementation of the Pressure Equipment Directive is available at


The link on that page to the full guidelines wasn't working when I tried to follow it, so I haven't posted it.

If the safety valves are designed specifically for the steam generator, they follow the category of it - otherwise they are Safety Devices and are placed in the highest category and are subject to CE marking.

Thread: battery problems
13/01/2018 11:14:40

I've had similar problems when batteries have seemed a 'sloppy fit' in the holder - it seems that not all brands of battery are exactly the same size.

Consider trying a different brand of battery.

Thread: End mills for alluminium
22/12/2017 16:27:31

Possibly even consider single flute cutters.


Thread: Single to 3 phase vfd
06/12/2017 09:38:30
Posted by David Jupp on 06/12/2017 07:24:40:

The screen is not really intended as the Earth - that should be a separate core.

Easiest way to connect the screen is to use proper 'EMC' glands to suit the diameter of the cable used.

That assumes the terminal box on the motor is metal - not one of those horrid plastic terminal boxes.

06/12/2017 07:24:40

The screen is not really intended as the Earth - that should be a separate core.

Easiest way to connect the screen is to use proper 'EMC' glands to suit the diameter of the cable used.

Thread: using an inverter to power a 3ph hoist
04/12/2017 11:29:28
Posted by Roger B on 04/12/2017 11:20:32:

The area I would look at is the brake. If it is entirely mechanical no problem. If it is spring apply electric release it should be ok but probably wouldn't allow for variable speed/ramping.

Many inverters will have a built in relay which can be used for things like operating the brake (check supply voltage for the brake). I know that some have built in functions specifically for use with braked motors - I've used them in a different application. When used in this way, a separate cable (or extra cores) is required for the supply to the brake unit.

Thread: Has anyone regretted migrating from MS Winows to Linux?
17/11/2017 12:32:43

Posted by Russell Eberhardt on 17/11/2017 10:58:30:

Posted by David Jupp on 17/11/2017 09:46:12:

I've looked at Linux a number of times - got very frustrated by how complex installing software can be (though for a lot of stuff it is fine). I have to use Windows for some of the software I use.

Linux Mint includes "Software Manager" giving you access to over 80,000 programs which can be installed just with a single click. I have Linux Mint dual booting with W10 on my laptop for the few programs which are not available for Linux. I use it for just Fusion 360 and for updating my GPS.


Perhaps I should qualify my comments - I did say " complex installing software CAN be..." the software managers in several Linux versions are arguable even easier than Windows, which is fine if what is covered by the manager is all that you need.

I've spent ages installing a Brother printer/scanner on a Linux laptop (Ubuntu actually) - this involved very close following of not very clear instructions on printer manufacturer's web site - all this done at the command line with little or no feedback on what was happening. I eventually got it to work. Getting DVDs to play on the same system was another long and drawn out process.

Don't even get me started about the software where the only instructions are mention of a few dependencies, or some gibberish about make files - with nothing to explain what this is all about.

There is some very capable engineering software that is produced for Linux - but when there isn't an rpm file or similar it can be a nightmare. I accept that a lot of that is down to whoever produces the software and (lack of) instructions.

One thing that is good about Windows is the software installation process - you buy the software, run the installer, and (the majority of the time) that's all you need to do. I know it does go wrong sometimes!

I'm not anti-Linux, it frustrates me that much of the Linux community wastes effort on creating multiple systems to tackle the same problem, yet (with notable exceptions) does very little to make Linux accessible to new users.

17/11/2017 09:46:12

I've looked at Linux a number of times - got very frustrated by how complex installing software can be (though for a lot of stuff it is fine). I have to use Windows for some of the software I use.

One thing I've come across recently which may be worth being aware of if you dual boot - Linux and Windows store CMOS time differently. Windows writes local time to CMOS, whereas Linux writes UTC to CMOS.

If you change OS (dual boot or swap system disk) it can take a while before system time gets corrected. Many modern licensing systems require contact with a remote server at software launch and will include a time check - if time is significantly out, the software will be disabled.

It is possible to configure Windows to write UTC to CMOS instead of local time - that might be worth looking into if you intend to swap OS.

Thread: Windows 10 printing problem
13/11/2017 17:33:59

Could be a failed or incomplete Windows update - have you checked the update history ?

What software are your PDFs printed from ?

13/11/2017 16:33:39

Check for latest driver package for Windows from the printer manufacturers web site.

Disconnect printer from computer, uninstall the printer, re-boot computer, run the manufacturer's set up program, following the instructions regarding when to connect the printer.

Thread: Setting up a website
05/11/2017 09:14:00

One option would be to use a Dynamic DNS service to point to your own system, then work just like you have done previously. Check first if you are going to run into bandwidth or monthly data allowance restrictions on your internet connection.

Thread: Simple Cad Drawing start-up.....
01/11/2017 19:53:29

Anything that will export STL files should be fine for 3D printing - that should include just about any 3D CAD package worth anything at all.

'Best' means many different things to different people. There is no single answer.

Some packages include tools that might give some guidance on suitability of a particular design to 3D print (though even that varies by printer technology & material).

'Small sum' is not very specific.

If it works for you, then by default it is 'good', no matter what others say or think...

Thread: Stepper motor driver
29/10/2017 08:39:53

I don't read the data sheet extract as suggesting pulse needed on DIR. It just says that the state of DIR input decides which direction the STEP pulse is treated as requiring. I can see how you could read it to think it's talking about pulses on DIR.

I've used a similar driver board, no need for pulses on DIR.

Thread: Upgrading a Denford Triac
08/10/2017 19:27:26

If budget is important, you might be able to re-use existing driver board & steppers by simply connecting a breakout board to drive from Mach3 (or similar) - that's what I did with my Novamill - OK you don't get microstepping, but it works fine.

Spindle drive - probably a 0-10V signal to either DC drive board or an inverter. With minimal messing about I adapted usied hardware in original Novamill cabinet to work from PWM output (would have been even easier if not for a fault on the DC drive board in my Novamill).

Lots of good info and help scattered around the denforddata site.

Thread: Denford Triac Mill
08/10/2017 19:21:36

Since I only had one easy change holder with my Novamill, I removed all the easy change stuff and instead substituted an ER collet chuck using the original manual drawbar.

05/10/2017 13:59:49

Triac and Novamill used a similar arrangement to lock holders in spindle when ATC was fitted. If you dig around the Denforddata site you'll probably find some drawings of the arrangement.

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