Member postings for David Jupp

Water jet will leave a tidier edge than laser cutting, which might be important.

It does highlight that most of the time we only quote a small part of the full material designation - and sometimes that leaves room for doubt as to exactly what we talking about.

Not surpising that with the many steel types in existence, and many different methods to codify them, that there are some with common character strings in the designation.

The lobed tap is likely a roll-forming tap, particularly common for use on thin material.

They work rather like ploughing a field (though not actually cutting) - tansferring material ploughed up from the furrow to form the crest of the adjacent thread.

Note that tapping drill size will not be the same as for a conventional cutting tap, but rather larger than that.

Edited By David Jupp on 28/09/2013 14:25:09

In general I find that life of those small cells can vary quite a lot - one factor is how long they have been laying around in the shop (or your drawer).

I suspect as well that some of the very cheap cells may not have as high capacity as 'known' brands.

It's also worth cleaning the contacts in the device when replacing the cell - a little dirt/grease can have a surprisingly large effect.

Remember most commercially produced bolts in 'every day' sizes have rolled threads not cut threads. For any highly stressed bolts that could suffer from fatigue take care.

Also 300 series SS typically much weaker than alloy steels used in HT bolts - may not matter for most, but take care with anything securing safety critical items.

Most fixings on cars probably aren't particularly highly stressed, but just be aware.

How about a scale 'River Don Engine' ? Go and see the original running at Kelham Island Museum, Sheffield.

Scaling it down will tend to make it (or any other engine) end up running much faster, with less torque - laws of physics apply even to models.

I won't comment on this particular package, as I haven't tried it.

Interesting from my perspective is that

1. RS obviously believes it will deliver some value to their customers (or they wouldn't offer it). The quid pro quo is that the associated tools integrate with RS ordering system.

2. I wonder if other companies might start to offer 3D CAD either free or at minimal cost - if this does establish a trend, I can see that there is a segment of the market which could go this way. These free packages typically omit most import/export capability - but that doesn't matter to everyone.

Will it end up openeing new users eyes to advantages of 3D CAD (some who then move on to 'full packages' ), or will it end up hitting sales of those 'full packages' as the free option is 'good enough'?

Edited By David Jupp on 21/09/2013 20:01:55

Edited By David Jupp on 21/09/2013 20:02:46

Edited By David Jupp on 21/09/2013 20:03:04

You could anneal it to remove/reduce the effects of work hardening - the 300 series work harden like crazy. Rapid cooling (water quench) is desirable after annealing (which sounds odd when you are used to Q+T alloy steels).

Colour is usually of minor significance with regard to either properties or identification of polymer type - most polymers can be coloured to any of a wide variety. Some pigments will alter other properties to a degree.

Some companies however may always purchase particular polymers in specific colours to aid internal identification (or to make any bits that fall off show up in the food).

Friction properties can often be modified by incorporation of various additives. The specific behaviour you witness may not be a natural property of the polymer - this can make identification even trickier.

BTW - don't be tempted to try burning tests on anything that might be a fluorinated polymer (including PTFE). People have died (Hydrofluoric Acid is VERY nasty and can be formed when these are burned).

Delrin is the DuPont brand name for acetal homopolymer resins. There is a familiy of different grades of Delrin (as is the case with many plastics). You might find some copolymer products described as acetal. Different manufacturers may use slightly different processes to produce chemically similar products, and there may well be subtle differences between products from different processes.

Most polymers can get very complicated if you start to look into the fine detail, and that's before people start modifying their behaviour with any additions.

Mine arrived this morning.

Another thought - those offering a laser cutting service will likely have automated nesting software that they use routinely. Though there might be some cost, it could save a lot of your time, and give better packing (less material use).

Have you tried Malcolm High at "Model Engineer's Laser" ?

DXF is probably most widely used for transfer to laser or water-jet , file should be a plain sheet (no border or info boxes), include 1 dimension value as a double check that it has imported correctly into the CAM software. Obviosuly (?) make sure scale is 1:1.

I can guess at your other points, but it would be better for soemone who knows for sure to advise you.

I eventually sorted mine (I hope) by going directly to the MHS site (via advert top right of ME home page) - that way 'add to basket' did work.  Had to search for 'Model Engineer' to find the special.

Reset password still does nothing as far as I can see, but I was allowed to order as a 'Guest'.

Edited By David Jupp on 04/09/2013 13:50:57

I trust there is nothing odd about it, but it seems strange to me that the 'Pre-Order' link shows as 'aimforprofit.com' , but immediately redirects to what seems to be myhobbystore.

I'm just a little concerned - I couldn't log in to order, and the forgotten password feature hasn't resulted in any e-mail to me with new details.

The belt can also take a 'set' if left under tension whilst the machine is not in use. This 'kink' can take a long time to work out of the belt. If you suspect this problem, try leaving it running for while to see if it improves, or just replace the belt.

Any simple pendulum has a period of

T = 2 π SQRT(l/g)

where l is pendulum length and g is acceleration due to gravity.

Weight doesn't directly influence the period.  

BTW The character after the 2 was Pi when it was input - doesn't seem to display well after submission.

Edited By David Jupp on 27/08/2013 13:40:31

Edited By David Jupp on 27/08/2013 13:40:56

Be aware they come in different sizes - I struggle a bit with text size in my own 'Toolbox' copy (even with my reading glasses). 'Larger Print' version or even CD-ROM version could be worth considering - CD version has extra content.

As for Edition - I suspect relatively little changes each year, but probably worth aiming for a fairly recent one.

Edited By David Jupp on 23/08/2013 12:42:22

Looks like each cable and pair of buttons provides a standard '3 wire remote' for a contactor. Since old colour code mains cable has been used I wouldn't wish to hazard a guess as to what colour goes where, or even if they are consistent between the two sets!

NC button should be in series with the contactor stop button, NO button in parallel with contactor start button.

Should be simple to anyone familiar with wiring contactors - plenty of generic information around, but if in any doubt call an electrician - better safe than sorry.