Member postings for Martin Dowing

There are kids like here in the past but mainly in Far Eastern societies.

Incidentally it is where our wealth migrates.

Plainly speaking Western societies are old , tired, turning decadent and yes - failing.

Insistence that everything must be safe produced environment where nothing can be done and "equal rights for all" culture in practice means "all rights for the stupid". This situation cannot go for too long before substantial loss of wealth and influence have occurred. We are already noticing it.

Healthy development of knowledge and personal responsibility does require that 1-3 kids in 100 get drowned, electrocuted, blow themselves up but rather alone in the fields while experimenting and not in crowded area for religious reason, chop off finger in the lathe etc.

Culture of safety nazizm is largerly preventing accidents like those mentioned above but this 1-3% are still lost to substance abuse, street violence, mindless operation of vehicle etc. Overall outcome in numbers is about the same but we are nurturing society of the stupid.

Martin

Edited By Martin Dowing on 10/03/2018 06:33:50

Edited By Martin Dowing on 10/03/2018 06:37:26

This is called "progress".

In any case our schools are good for nothing and cause brain damage of kids.

Martin

Many thanks both of you.

Thread from 2013 is very informative.

Martin

One of awkward issues related to ML7 but no longer present in Super 7 is lack of ability to turn wide angle cones using a top slide. Such cones are useful for example for turning a pulley. I know, pulley grove is often cut with a form tool, but I do not expect ML7 to pull this trick out, so I won't even try.

Initial inspection of task suggests that 4 holes could be drilled in the boring table at 10.30 am, 1.30pm, 4.30pm and 7.30pm or so, then tapped with1/4" tap and then as need arise these can be used for clamping the part on which top slide is sliding (holes must be matched with circular slots used also for usual clamping).

When not in use these holes can be plugged with appropriate setscrews to prevent swarf going in.

Is it how this job should be done or idea is daft and something more clever was worked out long time ago?

Martin

Long time ago, when I have bought my ML7 the same trouble cropped in.

First thing you need to do is to make sure that bearing housings are in allignement and it is not unknown for an odd monkey (eg previous owner) to overtension a belt enough to bend a casting.

If any problem here is noticed, it is not that difficult to twist casting back to allignement. Otherwise buy second hand one on ebay, but there is a good chance that you will need to do the same with it. After all there must be a reason to sell.

Once happy with it you may adress oilite bushes. I have used adjustable reamer to this end but there is a plenty of blabber on net that such treatment is detrimental to your bush (pores are clogged etc). IMO you will be fine as long as your reamer is sharp (if in doubt use new blades).

You are struggling for low melting point.

Alloys with 20-25% of silver, rest is brass are melting rather high and you will be able to work with only small items.

Alloys with 40-60% of silver, rest is brass are those which you are looking for.

Alloys containing 40-60% of silver, cadmium and brass as balance would be from engineering point of view the best (as they melt lowest, about 500-550 *C but not so nice for your health (cadmium). Best to work outside or under fumecupboard with these.

Fluxes - any borax based flux will do for general work.

Martin

Many thanks for comments.

It seems that on a small lathe like Myford we are talking about 100kG or 1000N of force while working reasonably.

So now I can buy these disc springs for stacking up "bumper spring". They are not very cheap so it is best to buy right ones at first go.

@Valentine,

Lever or hydraulic press and a broaching set is a right way to go with that. Or save some old good shaper from a scrap if you only have a space to keep it.

Martin

Hi,

Thanks for comments,

Handwheel in ML7 has effective diameter of ~75mm what gives circumference 235.5mm, say 250mm. "Effective" means diameter circled by handling knob.

One turn of wheel will give you 20mm of carriage travel.

This implies overall gearing ratio 12.5:1

So one should get 1250N (~125kG) force according to Neil or 2500N (~250kG) according to Silly Old Duffer.

We should take off 20% to address resistance on friction of slide and gears, so we are left with 1000-2000N (~100-200kG).

Probably 100kG because it is much easier to push against balance than turn a wheel.

I am designing bed stop with a relay system to turn off motor upon hitting it. Business end must have a spring loaded bumper to provide stopping distance to address pulleys and chuck inertia, however resistance should be sufficient so the bumper doesn't retrive during normal hand operation and stop is felt as such.

So I am calculating how much preload need to be applied to bumper springs. Stack of disc springs will be used.

Anyway, thanks for ideas regarding reasonable torque of hand.

Martin

What level of force can be produced by turning a carriage driving handwheel in pinion -rack system of ML7 assuming that an effort is kept within reason, not an attempt to break something?

Alternative question: what sort of torque (in N*m) one can deliver by hand by twisting action like turning a handwheel of lathe if effort is kept within reason? Answer should help to calculate answer to first question.

Martin

Many thanks,

Now I know how to proceed with that.

Martin

Hi,

Many thanks for comments.

Have decided not to lubricate, like usual with cast iron.

What diameter of drill would you use before reaming to 4mm? I suspect that 3.8-3.9mm is correct.

With larger diameters (6-20mm) I was always using drill 0.2mm smaller, at 20-30mm it was 0.3mm smaller but I have never reamed such a piddly little thing.

Martin

Geeks are buying over internet from wherever is cheaper.

To lubricate or not to lubricate, that is a question?

Edited By Martin Dowing on 28/02/2018 08:06:03

I would hold to 3 phase system with hands and legs.

Anything what 1 phase motor can do 3 phase motor will do better.

And if you can connect your motor in star or delta configuration, it will also allow for generous degree of speed control. You may fiddle with frequency and voltage to get speeds even higher than nominal without loss of torque. You don't need to be an electronic geek either to get there as adequate "in box" circuitry is commercially available.

You should smelt them under argon. You need to construct dedicated furnace for it. Crucible from magnesia (MgO) is best for the job. Load crucible with mixture of pieces of metals in right proportion. Temperatures in range 1000*C.

If both oxygen and nitrogen are excluded, titanium should dissolve in molten Mg.

Your alloy in all probabilities will be useless (issues with grain size, impurities etc). There is much more in metallurgy than smelting few elements together and hoping for the best.

I have hammer from beryllium copper (actually a speck of aloy was sent to ASA analysis to confirm that).

This hammer is rarely used (or actually not used because it seems precious). Anyway usual steel hammer works as good. Such tools are of use on oil platforms and they are unknown to cause disease.

One can buy few pieces of beryllium, for example here: http://luciteria.com/elements-for-sale/buy-beryllium

There are bike frames made of beryllium, $30000 a piece. Advantage - light weight.

I would take care with this metal. Heating can produce fine particles of oxide (BeO) and these are really bad idea for one's lungs. This material is one of very few, which I consider "dangerous chemical". Would prefer to work with cadmium, thallium, arsenic or uranium rather than with that.

Beryllium copper is fine but I would hesitate to braze it and if I have to then job would be *certainly* done on open air and I would use professional dust filtering mask.

Edited By Martin Dowing on 23/02/2018 20:12:22

Many thanks for your comments up to date. Those of Jason were particularly helpful but all are bringing important points.

House is relatively new and it is built up to high standards, definitely much above minimum regulatory requirements for residential house. I have one unused room on ground floor.

This room is good for nothing, my wife and me are not using it and kids are going their own way, they are doing very well and are unlikely to need any further help. So perhaps I could use it for a workshop.

It should not be too difficult to bring machine there. Ground floor, wide door along etc, albeit I am sincerely dreading this task.

I just wonder if *levelling* of 1 ton machine will be practical there. Even small deflections would spoil this exercise.

I have also one other option there which I didn't mention, namely to pour additional 3 - 4 inches of reinforced concrete. This would leave existing construction intact. This is possible because wooden floor mounted on wooden beams should be installed there as per original project, but it is not done. So this space could be filled with reinforced concrete and ceramic tails on the top.

Another option is to build a seperate workshop on my land (could be registered as garage or something alike) but it is much more expensive and I would also need to provide for heating, thermal insulation of floor and walls etc. I would not settle for cold and dark industrial type of premises or shed type of setup because I will be spending much of my time there.

Martin

Next year I will get a milling machine. I am aiming at something rather professional of weight in range of 1 ton, vertical and horizontal spindle, cooling system and power feed in both X and Y axis, with DRO but not a CNC.

Machine will be housed in unused room on ground floor of my property, about 170 square feet.

How such a machine should be bedded? There is a cocrete fllor there, about 2 or 2 1/2 inch thick. Under this is 3 inches of polystyrene foam, 6 inches of weaker concrete and then sand and soil.

I am concerned about polystyrene bit. IMO it will tend to sag under weight of machine, concrete floor may well crack and in any case I will not be able to level this machine proper. Simple idea is to dig out offending polysterene, fit steel construction matching stand of the machine and bed it on it. Or should I pour thick reinforced concrete square, say 4 x 4 feet, about 15 inch deep?

Any other ideas?

Being a chemist I do pay respect to hydrofluoric acid and there are rather few compounds which are causing my concerns.

So for example sulfuric acid diluted or concentrated is nothing of particular concerns comparing to HF.

Hydrochloric acid in comparison would be good handwash and cyanides only moderately poisonous.

Burns from HF have delayed onset (8-24hrs) so at the time of contamination nothing is felt, they are chewing tissue down to the bone and meet falls off the wound and tissue around simply rot. Healing takes many months. Wounds of older or sensitive peoples may never heal. Sometimes aputations are necessary.

Rubber gloves of industrial standard, rubber apron and face protection are mandatory and special paste made of calcium gluconate must be at hand to work into skin accidently treated with HF. Cacium gluconate paste applied promptly may (and often does) prevent development of said burns. Should be applied after initial washing with plenty of water BEFORE one seeks medical attention as time counts and waiting an hour or two or three will make it useless and doctors will have much more difficult case.

Saying all that I must note that HF is used in hobbies, say by glass staining/etching artists. It is branch of litography.

Martin

Don't know how large said leak is but military is known to underreport troubles (and losses on battlefield...), so leak could be more serious than we think.

Martin