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Member postings for Muzzer

Here is a list of all the postings Muzzer has made in our forums. Click on a thread name to jump to the thread.

Thread: VFD damage?
20/08/2018 22:52:14

Log or linear??? It's a speed control where the voltage sets the speed, so hardly going to be log.

Although it's badged as an Omron, it's actually a Yaskawa.

Best take the cover / back off if you are bothered enough to want to fix it. You might then be able to bodge an replacement pot in place of the original. The value won't be critical as long as it's between something like 5k and 50k - consult the manual for the approved range of pendant pot values to be sure, as it's almost certainly using the same reference voltage.

Murray

Thread: Chucking a Small Octagon (Delicately and Accurately!)
16/08/2018 13:47:18
Posted by Mike Donnerstag 1 on 16/08/2018 10:43:32:

I'm setting up as a violin bow maker...

Can be quite lucrative if you are any good at it. I know one of my sisters paid "several" thousand tokens for a violin bow not so long ago. As an engineer (and in fact she is one herself), I'd have to wonder how such an investment could be rewarded with any tangible improvement in sound, given that the interaction is between a (consumable) bundle of horse hair and the string. So the bow is surely little more than a handle, albeit an elegant and comfortable(?) one.

I'm a complete musical philistine, as you can tell. However, any benefit would certainly have been lost on me - in my case the money would have been far better spent on machine tools!

Murray

Thread: Squealing motor
12/08/2018 12:53:35

You shouldn't be putting lots of grease into new bearings - the actual amount should be a small fraction of the free space. The grease isn't supposed to spend its life as if it's inside a mincing machine. NSK recommend 10-15% and they should know.

You'd have been well off going for sealed bearings rather than shielded. Then you wouldn't be reliant on the questionable (in fact buggered) original seal. And as the bearings would be already lubricated by the manufacturer, it would prevent fists of ham trying to "fill" them with grease. I think we can be fairly certain that an induction motor would be capable of overcoming any minimal seal drag at startup.

Murray

Edited By Muzzer on 12/08/2018 12:54:00

Thread: Eclipse magnetic chuck/baseplate
11/08/2018 18:33:38

I doubt if he would have paid anything like full new price if he "picked it up" and plans to use it for welding, given that they are about £800 new but perhaps I'm wrong.

Lots of handbag action here but as I said, they often get thrown out or sold off when they are ground down to near the limit or just past their best. I turned down the opportunity to acquire one for free 2 years ago (and the grinder it was attached to). Both were well and truly buggered. Might have been tempted to use it as a welding table but I have enough junk as it is. Should it go straight from the grinder into the skip?

You'll see that most non-armchair welders don't bother clamping their work and instead find that gravity is usually sufficient to make an adequate contact. No arcing or sparking and certainly nothing to threaten the chuck innards or surface. It either strikes an arc or it doesn't. Unless you connect the only earth connection to the actuation lever I fail to see how you could knacker anything internally if you tried.

Murray

11/08/2018 11:46:19

I doubt you would damage the magnets with heat or current as they are hidden inside the body of the chuck. If this has no further use as a magnetic chuck on a precision grinder, it may well be a useful welding accessory. Using a brand new magnetic chuck for this purpose would be like using a Roller to pull a plough but if it's yours you can do what you like with it, particularly if you didn't pay much for it and it has had its day. A lot of these seem to get thrown out once they have been skimmed down a few times.

Murray

Thread: Are you a Man or a Mouse When Milling?
11/08/2018 11:37:22

Well actually my point was that the geometry of these cutters (tooth profile and asymmetric flute positioning) results in lower cutting forces and less likelihood of judder / chatter, which would actually benefit light machines. Hence my reference to the way insert geometry, materials and coatings have come on bounds. These cutters are as tough as hell but also razor sharp(!!) and make my Chinesium cutters look agricultural in comparison. True, you might not make full use of their potential but will most likely a better result. As ever, if you don't look, you don't find...

Think how the geometry ("chipbreaker" ), coating and composition of inserts has come a long way since we had basic, flat topped lumps brazed or clamped on the end of simple holders. That process of evolution continues today with solid cutters - they haven't been left behind.

If you buy them on offer, they don't work out too expensive.

Murray

Edited By Muzzer on 11/08/2018 11:37:45

11/08/2018 00:33:20

Like indexable inserts, solid cutters have come a long way and some of the most recent ones are pretty darned impressive. I suspect many of the "hobby" ones mentioned are pretty traditional in geometry and material - and possibly fairly indifferent in terms of surface finish.

I recently tried out a new-ish cutter from YG-1 (Korean), the "V7" EMC85 series. There are various flavours available but mine was a necked long series that I used for both roughing and finishing steel. The removal rate was pretty special and the surface finish was pretty darned good. Many cutters leave a clear series of grooves where the cutting edge in not smooth but these boys were almost mirror flat.

No coloured chips here, as I was using flood coolant to clear the chips but as you can see, I was achieving a decent material removal rate. To get the most out of these you really need to use CNC, as you couldn't sensibly apply the correct feed rate consistently.

Here's the roughing operation.

And the finishing.

Murray
Thread: Lead acid battery charging
10/08/2018 21:34:53

Trying to "trickle charge" a PbA battery via a bulb will simply overcharge it and then proceed to convert the water to gas. Probably about the worst thing you could do. Apart from drying out the battery, it will generate a fine explosive gas mixture.

Why not just buy a proper 6V / 12V battery charger? It will cost you less than the replacement battery you will otherwise need to buy.

If you insist on trying to charge it with a DIY circuit, use a regulated constant voltage source of 7V (14V for a 12V battery). It's no great coincidence that this is the voltage generated by the alternator regulator and corresponds to the float voltage of a fully charged battery.

Murray

Thread: Spares for cheap Bandsaw
06/08/2018 22:58:52

Funny - the generic 4x6 Chinesium bandsaw doesn't use these tires / tyres - the blade runs directly on the cast iron drive wheel. Yours may well work without needing a replacement if you remove the perished remnants. Just a thought....

Murray

Thread: Hand files for aluminium
06/08/2018 11:45:34

These latex blocks are just brilliant for declogging belt sanders. I haven't tried it with a file but suspect it may be another effective way to clear teeth, particularly if combined with PTFE spray or WD40.

Murray

Thread: Couple of things at Lidl
04/08/2018 19:34:08

Stick them in the airing cupboard or in / on the boiler to keep them dry. If they are damp, you can put them in the oven at low temp to dry them out. Even better, get a sealed welding rod container.

Thread: How to drill holes in ABS plastic without splintering?
04/08/2018 17:49:43

Could well be ABS - but with high percentage of degraded regrind, used as a way to dispose of ("recycle" ) flashing and sweepings. Every time the material is melted in the moulding machine, it degrades but many moulding companies like to minimise the amount of stuff they have to dispose of, so they feed it back into the mincer.

I have some of those "Hippo" type builder's buckets from Aldi that are nothing like as tough as the real thing but that also includes the price which is bargain buckets in comparison. I expect they have recycled everything but the kitchen sink into those.

Murray

Edited By Muzzer on 04/08/2018 17:49:57

Thread: What did you do Today 2018
03/08/2018 23:15:03
Posted by richardandtracy on 30/07/2018 22:50:27:

Have to ask - is the propensity for an astrophysics degree contagious, using a telescope as the vector?

Certainly seems that way. Following her acquisition of a half decent telescope at Xmas, she is about to start a masters in astrophysics at Manchester. Don't worry, she will still be an engineer, albeit a star-eyed one, having got a first in mech eng. Don't know where she got that from....

Proud dad

Thread: Aircraft General Discussion
03/08/2018 22:18:04

Interesting video of P-51 forced landing short of Duxford after engine failure. I always felt a little nervous during air shows when I lived locally, even if we benefited from some glorious free displays!

Murray
Thread: Internally finned box section heatsink
03/08/2018 20:08:59

Generally these wind tunnel type heatsinks are designed to accept a fan on the end, yet not many fans come that small.

You seem to be suggesting you had something like this already, although I suspect it must be a minority sport and may be very difficult to replicate. I've certainly never come across anything this small.

Murray

Thread: Inverter Drives for Motors
03/08/2018 19:59:16

I'm afraid that you won't get electrical installations signed off by Building Control unless you can produce a certificate to show it was done (or at least signed off) by a Registered Domestic Installer. Just telling them you know what you are doing won't cut it. And if you don't get installations signed off by Building Control it is likely to be picked up by the buyer's solicitor when you sell the house.

To become a competent person seems to cost you £500 or so and requires practical assessment etc. In my case, although I've spent most of my career developing products like VFDs, chargers, power supplies and even RCDs, I am not considered a Competent Person. So I simply get it inspected, tested and signed off by someone who is. And to be fair, the fact that I've designed products doesn't necessarily mean I am capable of installing them safely taking account of the regulations that have been developed over decades as the result of much empirical and theoretical knowledge. You need to read up on the latest version of Part P and also the guides to how to apply it in practice to stand a chance of getting it right.

Murray

Thread: Milling for beginners
03/08/2018 11:57:58

Don't see the point applying coolant by brush to carbide tooling (or any, other than hand tapping for that matter). Seems to be essential behaviour in the US - but on this side of the pond?

Thread: Mercer British
02/08/2018 13:17:03

Before BAE blew the wheels off the Honda-Rover partnership, you could buy the same basic car from either, as either the Rover 200 or the Honda Civic. The 200 had a the unreliable Rover K Series engine and crap build quality, whereas the Civic had a Honda engine and was built by Honda on their own line. As if that wasn't enough, the Rover actually cost more. Why have cotton when you could have silk.

I was mightily relieved when Rover finally went out of business. It was both a national tragedy (not least for the workforce) and a downright embarrassment - and the people who ran it towards the end (Towers et al) seemed to behave like criminals, selling the assets for their personal gain at the expense of the pensioners.

The Roewe brand lives on in China and we have now started to see some of the new MG vehicles on the roads here. Wouldn't be surprised to find they are better engineered and more reliable than the old Rovers, despite being substantially Chinese.

Murray

Thread: 3-Phase Motor Conversions: Are They All Hype?
30/07/2018 18:08:24
Posted by John Paton 1 on 30/07/2018 15:33:02:

Three thoughts:

1. Make sure you know how your motor is wired and connected (star or delta configuration?) It does make a difference and the motor may even burn out if it is wrong.

2. If the inverter is correctly set up you should be getting 415v across two phases. You can check this with a meter

3. If you are unsure, please get a competent electrician to assist - 415v will kill whereas 230v usually doesnt!

1. You aren't going to burn anything out if you miswire it. Once you reconnect it in delta it should be fine. Just make certain you have set the maximum phase current to whatever it says on the nameplate and check if it's 2 pole (2900rpm) or 4 pole (1450rpm etc). You should get that right in the config too if you want to fix the issue. It would still work fine if you configure the wrong number of poles but if your display is in RPM rather than Hz, it will display speed incorrectly.

2. Wrong - you should see 230V phase to phase unless it's a special VFD that boosts the voltage internally (I think we have been told otherwise).

3. Not sure I'd go with that. 120V may be a lot safer than 230V but I wouldn't argue the toss between and 230V and 415V. I've had 415V across both hands and am still here to tell the tale but it could very easily have been curtains. I CAN tell you that it actually hurt like hell and I haven't done it again since.

Murray

Edited By Muzzer on 30/07/2018 18:10:31

Thread: What did you do Today 2018
29/07/2018 15:37:18
Posted by Robin on 29/07/2018 15:00:23:

From my chemistry days I seem to remember that nitric passivates iron, so after a brief fizz you get nothing. Alum dissolve iron, caustic soda to dissolve aluminium. Nitric is good for degreasing aluminium and getting that pesky oxide layer off the surface. We used to put old copper coins in brown sauce to clean them back to the shine, I think that contains nitric..

Doubt it - that'll be vinegar aka acetic acid. And Coca Cola contains phosphoric and carbonic acids.

Murray

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