Member postings for Andrew Johnston

Depends upon the type of motor. A brushed DC motor is quite likely to be way noisier than a switch-mode PSU on a PCB.

Was the trip over-current or earth leakage?

Electrolytic capacitors are reknowned for swelling before failure. But I've not seen the same with other types of capacitor. Normally one would expect to see an X-rated capacitor across the supply and Y-rated capacitors from live and neutral to earth. If the equipment is double-insulated then there is no earth and no need for the Y capacitors. Both X and Y capacitors are metallised film and are self-healing as a short circuit failure is unacceptable. If the film is punctured the local metal film is designed to evaporate, removing the short circuit.

A picture would help identify the components, and possibly the problem.

Andrew

Now you''ve got a man sized drilling machine just drill 8mm and be done with it.

Andrew

Any industrial tool stockist should have, or be able to get, keys for Jacobs chucks. Here's a link to the manufacturers technical page:

**LINK**

The stockists they list are in the US, but plenty of UK stockists for chucks and keys. I'd be suprised if the same wasn't true for Europe.

Andrew

You get the same flat, but only on one end. So the work needs to be swapped end for end on each pass.

Andrew

Mark: Thanks for the explanation.

Gerald: It should run fine in star. If you look at your diagram in high speed mode wires 4, 5 and 6 are connected together, but they don't go anywhere. You don't need a neutral line to run a motor in star. In theory the current in a neutral wire would be zero.

Andrew

Good grief, that's going to be flexible. I don't think you need worry about spindle loads, any sort of cut and you may well get more chatter than an Islington luvvie. And there was me worrying about whether a 50mm face mill would be too big for a Bridgeport.

Andrew

Thanks for the additional information. I read somewhere that oxy-propane isn't great for brazing, but can't remember where. Superficially one would have thought it would be fine, as the temperature is much lower than needed for welding.

Much to my surprise the Air Liquide lorry turned up at lunchtime with my refill bottles. Unfortunately I was so surprised I injured myself falling off the chair! Naturally the delivery was a foul up. One, the delivery price was not what I thought I was paying and two, he seemed surprised that there were two bottles to collect. He was pleasant though. Said he'd delivered to me before. Quite possible as when I bought my DC/AC TIG welder I had the argon bottle delivered, as it is too large and heavy for me to lift. But that must have been 10 years ago. He also said I'd be better off with Albee bottles as I'd own them and there's no delivery charge. I mentioned the regulations and the fact that I'm a hobbyist and he agreed I am exempt, but said it was company policy not to allow pickup. He related a story of someone turning up at the shop with a trailer full of propane and acetylene bottles all rolling around in the bottom of the trailer. It's idiots like that causing the blanket ban on collection.

Andrew

Clearly the switch is changing the number of poles. But if that's all it's doing why aren't the low/high powers also in the ratio 2:1?

Andrew

It may be switching from star to delta, but is also pole switching from 4 to 8. The key is the last part of the plate:

700/1420 U/min

In other words 700 and 1420 rpm in low and high speed respectively.

Andrew

I expect the original was cast. The angles look far too tight for the thickness of material to be bends, and the thickness of the material seems to vary a lot.

Andrew

Not my end; my operating system is no longer supported. So definitely no updates I didn't know about. I'm normally logged out, and only login when I want to make a post or read a PM. I don't have a 'spam' folder. Thanks for looking anyway.

Andrew

For ages I've been getting an email to say I have a PM. In the last few days the emails seem to have stopped, even though I have PMs waiting. I've checked that I still have the notification box checked. Also unchecked, saved, checked and saved again. It still doesn't work. What gives? Smacks of an IT 'upgrade' to me!

Andrew

RUN IT AT 50Hz - IT WILL BE FINE!

I've just had a quick look at the link again. Got as far as the first paragraph where it says motor speed is dependent upon voltage and frequency. No point in reading any further.

Andrew

Unless you're machining copper.

Andrew

Possibly, in theory. But in practise the standards used in the factories would have been orders of magnitude less accurate than the variations in the definition of the inch.

Andrew

I would think that they're up in the 100s of kHz these days. Even 100kHz is so passé.

Low power DC-DC buck and boost converters are up to the low MHz, and use inductors rather than transformers. An offline switcher may need a transformer depending upon isolation requirements. Inductors are preferred as they're small and surface mount and don't need fancy formers for the windings. Higher power converters that need bridges tend to use transformer based designs, although the transformer windings can be part of the PCB.

I don't know what a 240V in, 415V out VFD uses to boost voltage. But given that more expensive VFDs probably incorporate a power factor corrector at the front end rather than a simple rectifier it would be simple to use the PFC to generate the higher voltage needed for the DC link. A PFC is basically a boost converter. There are two big cost impacts caused by the higher DC link voltage. The bridge transistors and DC link capacitors need to have much higher voltage ratings.

Andrew

The manufacturers data for my machine vice shows that the clamping force (lbs) is very roughly 90 times the torque (ft-lbs).

Andrew

The Air Liquide (AL) saga continues. Naturally no delivery by late Friday afternoon. So I called AL customer service and explained the situation to a very pleasant lady, who commiserated. She must have called the agent because she said delivery would be next Tuesday. I explained that while that is sort of ok for me any sort of commercial welding outfit would be mighty pissed. Also said that I was pissed because I didn't know when, which makes it impossible to plan activities. It's a real waste of time if you're expecting a delivery and have to wait in. Even nipping out for 10 minutes could be a disaster. My number one rule in these situations is to be polite, but be a polite PITA to the extent they realise you're not going to fobbed off. Then it's easier for them to sort the issue rather than woffle! The issues have been sent to the sales manager and, in theory, he's going to call me to discuss service and delivery pricing. I also said they were wrong on the ADR regulations as I was a private individual using gas for leisure activities. She said she'd contact the AL safety group for comment. I don't suppose I'll win the battle, but at least I've raised the issue.

After a bit of confusion over dates I confirmed that my rental agreement ends on the 31st of October 2020. So I've got time to look around elsewhere. I've got a lot sheetmetal flanging and welding to do on my engines so I aim to get on with it so I can refill bottles while I've still got a current agreement.

Roll on Tuesday!

Andrew

DD is correct, it's a hydraulic copy unit. The tool on the back of the cross-slide is driven by a double acting piston. The T-shaped extension below the tool slide carries a stylus that replicates the shape of the tool. Through a series of valves and channels the tiniest movement of the stylus unbalances the piston so that the tool slide moves until the pressure on both sides of the piston is equalised. The effective gain is high so there's almost no error in following the path. The movement of the tool in and out is controlled purely by the template. The axial movement is controlled purely by the lathe feed mechanism. The slide is at an angle to the work so that at the end it can move perpendicular to the work. If the slide was perpendicular the feedrate would need to be infinite.

The shape and, to some extent, surface finish is determined by the quality of the template. Although my template is filed as I don't need great accuracy it would be surprising if I'd got a small ridge almost exactly every 5mm. Especially as I finished by draw filing in short lengths.

I've used the unit on other parts and not seen the same effect, albeit the parts were much shorter.

The mystery remains unsolved.

Andrew

In a word 'no', but I haven't seen the effect before, either sliding or facing.

Andrew