Member postings for Robert Atkinson 2

I can't comment on Bloodhound, but have a few stories about the brake 'chute system on Thrust SSC. For starters The ribbon 'chutes needed an export licence - they were retardation 'chutes for a nuclear weapon. Most of the rigging parts cme out of Richrds garage aving been left over from Thrust 2 and they were surplus in '83. We had numerous failures for various reasons. I designed the circuits that fired the explosive squibs used to launch a bolt that pulled the drogue chute out. The squibs were left-over / the same as Thrust 2 and I could not get the mating plugs. I plead the 5th, but if you look at Thrust 2 in the museum in Coventry you will see there are no squib connectors......

Robert G8RPI.

Edited By Robert Atkinson 2 on 28/11/2018 18:30:09

My reasoning for supply drop parachute is because the "clip" is clearly designed to release cleanly even under load and is also designed for manual release. Multiple attachment holes on one suggests prachute lift lines. If you were chasing a supply can being dragged by the chute this is just the kind of release you would need. It's not heavy enough for any brake chute I've seen. Might have been a drogue 'chute for an ejection but that woud not need the manual quick release.

Robert G8RPI.

Maybe, but I think they are cargo parachute attachments.

Robert G8RPI.

The T8 LED replacements have raised safety concerns too. See

**LINK**

While I'd not agree with everything in the report **LINK**

Clearly care should be taken. Labels saying "BALLAST REMOVED LED LAMPS ONLY" would be a good start.

Robert.

No issue owning a cutter. If you make slow match I'm sure you are aware of some of the illogical UK firearms laws. For example you cant own a "realistic replica firearm" unless you are a recognised re-enactor film maker or similar. So you can't own a diecast light alloy replica of for examle a "cap and ball" revolver. You can however collect antique firearms and own a real one without any licence or similar conditons. This ebay item is technically illegal

https://www.ebay.co.uk/itm/Hawk-Jet-Fighter-Suppressor-Ex-MOD/323344002300?

but as it's for an Aden cannon I guess no one is bothered. More use as a blunt object than a silencer

Robert.

I hope you have a EPP licence for the lead acetate

https://www.gov.uk/government/publications/supplying-explosives-precursors/supplying-explosives-precursors-and-poison

and

https://www.model-engineer.co.uk/forums/postings.asp?th=136405

Robert.

Or search ebay for "wash bottle"

The problem with lead free solder is tin whisker (crystal) growth that causes short circuits. Google it if you want to know more. There are exemptions for the use of leaded solder on high reliability applicatioons these include aerospace some network equipment and automotive. The automotive exemption is good until 2023 but Ive no information of who is or isn't taking advantage of it.

http://www.indium.com/blog/elv-2014-high-lead-pb-in-automotive-electronics-is-good-until-at-least-2023.php

The cynic in me says consumer equipment makers love tin whiskers because they take longer than the warranty period to grow.

Robert.

I can assure you thet REACH and COSHH DO apply to tradesman and companies. actually to a greater extent. The Aerospace industries are facing a potiential crisis over hexavalent chromium. This is banned but aerospace have been working under a wavier that was not ratified and could be cancelled It expires soon anyway. Hexavalent chromium includes chromic acid which is used in many anti-corrosion surface treatments for light alloys (Alochrom etc). There is no approved alternative for many application and some non-european aircraft manufactures seem to have little interest in approving any alternative.

Robert.

Try a local Airconditioning / refridgeration company. The will probably give a couple of feet of off-cut if you ask nicely.

Getting imperial size may be an issue but you neve know.

Robert G8RPI.

When going faster two ribs way be required

Yes those are the steered wheels at the back.

+1 for Sikaflex for Kingspan to steel door. It's used to hold commercial vehicle panels and trim together, not just solar panels on. Alternative similar product is Tigerseal.

On safety precautions for PinkGrip v DIY products. It actually the consumer products that are more hazardous than professional ones. The reasoning is that a professional is exposed to the product every working day for years while the consumer might only use it one a week, month or year. Under COSHH and REACH many workplaces ban the use of "consumer" cleaning products.

Robert.

Neil,

Rather than a conditioner, if you have a variable DC supply cable of at least 18V (higher is better) with current limit it will do a good job. discharge the batteries. Set the current limit on the supply to 1/20th of the Ah rating of the battery (or 80-90% of the power supply current rating if less) and turn the voltage up maximum. Switch on and connect to battery and leave connected for at least 48h. If voltage is below 14.4 V, set voltage to 13.8V and leave forr another 48h. A lot of battery chargers have high ripple and lead acid batteries do not like this. a good DC supply is much better for them.

Robert G8RPI.

Hi Sam,
As Andrew says the voltage will vary with charge, discharge and resting. Temperature also has an effect. It sounds like your batteries are fine.
Do you know what voltage your charger switches to trickle at? The initial charging voltage at 6A of 13.7V seems a little low and is probably due to the length / sixe of the cables connecting charger to battery. I'd expect to see at least 14.2V at the battery before it switched to trickle mode. I assume you were not there when it switched.

Robert.

Lock washers are not placed under the head of a bolt in a nut and bolt assembly because the shank of the bolt provides additional friction.
Spilt / spring lock washers do add tension as well as friction but put an off-set load on the nut and thread which can be a fatigue issue in high load applications. Star washers are virtually useless in high load applications. They flatten and are just high friction. Both types damage protective coatings /surfaces. There are "Wave" type spring washers that are better with small fasteners. and don't damage the surface.

Critical nut and bolt designs lock the nut to the bolt, either directly or both to the substrate. Really critical ones like aircraft controls have thread locking and a secondary means of preventing the joint coming apart.

Google aircraft thread locking.

Robert.

That would be very straight forward to wire up but you would have to press the button every time as well as using the foot switch. The other problem is you could press the switch but not use the lathe leaving it "armed" and then comeback later an start it inadvertently with the foot switch. A cover on the foot switch would be a good start. Maybe even with a door or bar guard you have to lift or push with the toe of you shoe to get your foot under the cover.

Robert G8RPI.

LPS-3

**LINK**

Not cheap (£12 for a 300ml spray can) but very effective.

Robert G8RPI.

You did not answer Bazyle's question, is the foot control ON/OFF or a variable speed control?

Also you imply that the power is going to the "potentiometer" I assume this is a manual control knob fir the speed controller and not an actually carrying power to the motor?

Normal arrangement as said is a momentary start/stop button but this does not directly tie into a pedal control. Having to press a start button each time defeats the purpose of a pedal control (other than as a secondary safety function which is not your case). My solution would be to have an "ARM" button. that enables the footswitch for a limited time. Functionally, pressing the arm button would start a time delay (relay) enabling the foot switch. if the foot switch is pressed within the pre-set time the machine runs and the time delay is reset and starts again when you release the foot switch. If you don't press the foot switch (again) within the pre-set time the foot switch is disabled until you press the arm switch again.

The timer could be an electronic circuit made for the job or a general purpose industrial timer like those made by Omron IMO etc. It could even be a microprocessor like a PIC. An "ARMED" light would be a good idea.

Robert G8RPI.

A number of people have commented on the inability to use VFC/VSD on equipment with control gear or multiple motors. While it is true that there are difficulties using the variable speed capabilities due to the associated variation in voltage, there is no reason why a converter / drive cannot be left set on 50Hz 100% voltage to provide a 3 phase supply for such machines. You loose the advantage of variable speed but at least get the unit working. Some converters may need a small fixed load for stability but this could be 3 small lights or heater elements.

Robert G8RPI

Having had a couple of cheap ones shear off when using a DeWalt 1/4 hex battery driver I bought a Wera one part no 870/1

http://products.wera.de/en/bits_holders_adaptors_holders_adaptors_connectors_adaptors_870_1.html

You can also get a set https://www.machinemart.co.uk/p/040212181/

Robert G8RPI.