Member postings for David Jupp

Extrusion based printers are just one of many available technologies. You are correct that generally build time vs resolution is always a compromise. Some technologies can 'grow' a whole slice at a time, reducing build time (though these tend to be more expensive machines).

One of the most impressive machines I've seen uses ordinary A4 paper as the raw material, and cuts each sheet to laminate to the 'stack'.

mechman48 - PM sent

Quite a scattering of us based in the NE I think (Tesside in my case).

Your best bet is probably to put something in the for sale ads on this site.

All I recall about grinding and aluminium is being told very forcefully that it should never be done - soft metal clogs the stone and can lead to it shattering. Now there may be some specialist process that avoids that - others may know?

Rolled aluminium will be flat to a pretty high standard. Keeping protective coating in place until late in the day will reduce chances of marking.

You don't mention what coating is planned - for paint an etch primer is typical on aluminium. Others have already suggested anodising, which might work well for some coatings (be aware there are several variations on anodising with differing end properties).

The cutting technique used may introduce variations in flatness.

Simple, effective, inexpensive - what more could you ask for...?

Don't under-run halogens by too much, that also can drastically shorten the life, evaporated filament condenses on cool glass giving black layer rather than re-depositing on filament...

Edited By David Jupp on 27/07/2013 18:18:49

The blade should lift slightly on the return stroke.

On my Q+S hacksaw if I drop the blade to just above the work, pause it using the hydraulic damper, then start the motor, the blade starts to lift (I quickly move the damper control to drop the blade on to the work).

The Q+S has a 2 positions for the damper control (plus fine adjustment).

There is a correct direction of rotation - on the Q+S this is marked on the crank drive wheel. You can check this as the connecting rod to the blade carrier should pull slightly down on the cutting stroke and push up more noticeably on the return stroke. If rotation is wrong it should be quite easy to spot.

Connecting rod should be close to parallel to blade on most of cutting stroke - noticeable angled to it for most of return stroke.

Chrome Vanadium doesn't really tell us (or you) what the steel is - just 2 of the alloying elements it contains. I have seen those words on a lot of spanners over the years - though I have no idea why spanner manufacturers should go to the expense of adding the letters to the forging dies.

Assuming there are no particular chemical issues relating to the environment of use, select on strength of the steel for the required duty (on BS steels the 'condition' letter tells you the strength). Don't worry too much about composition of the steel.

Where there will be sliding or rubbing against another steel component, ensure a strength (hardness) difference between parts to reduce scuffing/galling.

For safety critical items (pressure vessels, lifting equipment - possibly couplings) the toughness of the steel is also important in avoiding fatigue failures. Toughness generally reduces as strength increases, so stronger is not always better - a balance is required.

BTW EN24 is a Nickel Chrome Molybdenum steel having about 0.4% Carbon (also contains Silicon and Manganese) .

Or Servo Drives instead of steppers where higher performance may be required.

If you are feeeling adventurous, do a web search on 'housekeeper joint'.

Don't confuse the marginal cost of production of drawings with the the 'all up' cost. It's a bit like comparing just the cost of petrol for a journey with the equivalent train or taxi fare (conveniently ignoring the money already put into buying, insuring, taxing, maintaining the car and paying the driver).

The air rifle book raises interesting points - if sizes can be kept 'mainstream' and enough copies produced/sold then both the unit costs of producing fall, and any payment for designer, or element of profit can be spread over a greater number of units.

Some people design / publish 'for the love of it' - some are running a business, some are in between. Don't be surprised that they do their accounting differently.

You also have to pay for the facilities to (large format) print / store / retrieve them. I suspect the 'the amount that must have been sold' isn't actually all that many to spread the costs over.

For each order somebody has to either retrieve existing copies from storage, or 'print on demand' the required sheets, then fold, pack and ship. It all takes time.

If you look at it as buying the designer's time and ingenuity, it's a lot better value than if you think of it as buying paper.

In many ways we are spoilt with so much in the way of plans and designs available for free on-line.

See table of BS970 Temper condition codes asbout half way down page on this site **LINK**

T = 850MPa - 1000MPa UltimateTensile Strength or 55 Tsi to 65 Tsi in old money.

So no not fully annealed, but not terribly hard either

Neil - that doesn't sound quite right -

Fwd-off-rvs, if wired via momentary start p/b, then the 'off' of the 3 position switch can't do anything (except act as a disable).

Not familiar with the Jaguar - some inverters offer more than one switching mode dependent on how you want to control it.

One that I use here is set to mimic a NVR contactor behaviour (3 wire mode) - n/o button to start, n/c button (and any interlock switches) to stop. The same inverter can also be set to have a single contact - closed for run, open for stop (2 wire mode). On my drive, fwd/rev is done via a simple on/off toggle switch, as is jog mode.

Mine is not a Jaguar drive though - so the handbook should be your ultimate guide.

From my original training in metallurgy, and some quick checking of a few technical web sites, I'm not convinced that there will be any significant age hardening in copper as used in typical ME projects.

If age hardening did occur, it could be speeded up by heating to the correct temperature (to speed up diffusion) - heating too much would drive the precipitate forming elements back into solution and hence soften the metal.

There is age hardening in materails like Beryllium Copper, and Copper is used as an age hardening alloy addition in Aluminium and some other metals.

As commented by others, very significant work hardening does take place in copper.

Edited By David Jupp on 15/06/2013 11:29:18

It is even possible to buy tools which can be used to both mill the hole and the thread - biggest benefit is cutting down on tool changes.

Marchant Dice stock this kind of stuff. They already do (or certainly did) kits for the Rockliffe router. They trade on line and via e-bay. Probably lots of other options out there.

The size will usually be marked on one face of the die. Should allow a quick check.

I think that I might be tempted to try using loctite (or similar) to hold the ends on - would save all that very fine threading - unless the screwed cap also pinches the rod seal...

Or maybe try to find some off the shelf brass steam fitting nuts that could be modified.

Or drill/tap thru, add male threaded plug - solder plug to seal, drill for rod.