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Member postings for Neil Wyatt

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

Thread: Petrol Gen for 7 1/4 locomotive
15/09/2019 14:43:27

Have you seen recent issues of ME? There's a series looking at exactly this in detail for a 7 1/4" loco.

Neil

Thread: Syil X3 CNC Spindle Failed
14/09/2019 18:20:46
Posted by Michael Gilligan on 12/09/2019 18:33:29:
Posted by Neil Wyatt on 12/09/2019 16:25:09:

'DC Brushless motors' are fed from a switched DC supply rather than a true AC supply.

So a typical VFD outputs three sine waves (or at least approximations of them using PWM):

A BLDC controller outputs three differently phased square waves, using pulse width modulation to control the power:

.

Neil.

Is it too much to ask that you quote references when you are posting images like those ?

... You presumably found them on t'internet, or scanned them from a document ... but it's tedious trying guess your source.

Thanks

MichaelG.

They are embedded images, so you can find their origin easily in several ways.

Neil

Thread: Engraving
14/09/2019 18:19:18
Posted by old mart on 11/09/2019 20:49:15:

As usual, the text which is written first, ends up stuffed in the middle of the photos which appear in the opposite order that they were added.

Move the cursor back to the end before adding each photo.

Neil

Thread: DAG Brown Injector and Ejector Designs - Very Impressed
13/09/2019 20:53:39

I'm sure your comment will reach him

Neil

Thread: CRT Free!
13/09/2019 20:50:26
Posted by Andrew Tinsley on 12/09/2019 22:31:41:

P.S. After a lifetime involving high vacuum kit. I do know how to destroy a CRT safely!

My dad used to wrap them in a big, heavily padded mat and drop a brick on the bit with the connectors from about 15 feet above...

Thread: drillling bronze
13/09/2019 16:25:00

Apparently phosphor bronze contracts around a drilled hole.

Neil

Thread: CovMac Lathes
12/09/2019 20:43:28

Nice to see these big old lathes being looked after and used

Neil

Thread: Vickers Bl 8 inch Howitzer cannon of 1917
12/09/2019 18:15:51
Posted by duncan webster on 12/09/2019 00:20:41:

This gives a description of the Welin Breech Thread.

**LINK**

I've always wondered how they were made, so I'm looking forward to next week's exciting episode

Making one was covered in ME... wait a bit...

1 November 2002, issue 4181, page 440 "A Welin Interrupted Breech Screw in 1:15 Scale", David Wilcox.

Also see postbag in issues 4017 and 4023.

Neil

Thread: DAG Brown Injector and Ejector Designs - Very Impressed
12/09/2019 16:27:26

If you can attend any model engineering shows where the SMEE are exhibiting there's a good chance you will be able to meet Derek and thank him yourself.

Neil

Thread: Syil X3 CNC Spindle Failed
12/09/2019 16:25:09
Posted by Ian P on 12/09/2019 13:13:50:

I know nothing about a Syil X3 CNC milling machine but are you saying it is fitted with a 230VDC brushless motor?

A brushless motor only becomes a 'DC' motor when it is combined with electronics, the motor itself is driven by several windings and they need the correct AC type waveform to cause the rotation.

'DC Brushless motors' are fed from a switched DC supply rather than a true AC supply.

So a typical VFD outputs three sine waves (or at least approximations of them using PWM):

A BLDC controller outputs three differently phased square waves, using pulse width modulation to control the power:

Thread: Matt Reid - Dalton Lathe
11/09/2019 21:00:44

This means Matt hasn't entered his contact details.

Hopefully he will see your post and edit his ad.

Neil

Thread: Steam Hammer identification
11/09/2019 20:37:28

Interesting model.

Watch your fingers...

Neil

Thread: Why are insert toolholders so expensive?
11/09/2019 20:15:49

Industry also demands traceability and supply on demand. They are more interested in getting back up running fast than saving a few quid.

That's why suppliers like MSC/Cromwell charge a lot - they are holding a massive variety of obscure stock, some of which they will never shift, as their customers expect to be able to order the most obscure tooling and get it straight away. It's also why they sometimes have sales to get rid of overstock.

'Our' suppliers concentrate on a smaller range of sizes and therefore have to hold less stock and have higher turnover of goods.

You'll see the same with farnell and CPC. CPC will often sell a part for less than Farnell or in smaller quantities at the same price, yet they are effectively the same supplier - but CPC has a much more limited range.

Neil

Thread: What Did You Do Today 2019
11/09/2019 20:04:50
Posted by Mick B1 on 11/09/2019 15:31:05:

Yet another racing car, ultimately for the grandkids. Generic sort of 1920s shape, OAL approx. 78mm., wheel track at Brio gauge.

Brass/Delrin/PB102/Titanium - the Ti hubcaps were torch-blued in the lathe before parting off.

All machining was in the WM250V, with vertical slide for milling and drilling.

img_3299.jpg

More sophisticated than my attempt (which I won't photograph).

10/09/2019 16:43:35

I even resorted to grinding the corners off a spring clip with the dremel after it had claimed too much of my blood!

Neil

Thread: Lathe rigidity
10/09/2019 16:42:22
Posted by not done it yet on 10/09/2019 14:46:49:
Posted by Michael Gilligan on 10/09/2019 13:57:51:

Infinitesimal, perhaps ... but definitely real : Any change of preload requires movement.

MichaelG.

Not true. If a force is applied, an acceleration should occur (Newton’s Second Law of Linear Motion) - unless that force is nullified by an equal force in the opposite direction. That is all that occurs when a preload is changed. No force, no preload.

Every preload force is opposed by an equal and opposite force - unless something breaks (and preload will reduce to zero). Bearings don’t move, only the force applied changes. You can’t actually have zero preload as the bearing races could be together or miles apart! If anything moves, it will be the housing, not the bearing, per se.

Bearings are not inelastic, correct preload implies a small amount of elastic deformation shared out between bearing, spindle and housing acording to their materials and design. This can only be achieved by the relative movement of inner and outer races.

Some high speed spindles are designed with the bearing a close sliding fit and a spring to apply prelaod.

Neil

10/09/2019 16:37:51
Posted by Michael Gilligan on 10/09/2019 13:51:29:
Posted by JasonB on 10/09/2019 13:13:37:

.

The need is for a close fitting bearing inner ring that can still move under the load applied by the adjusting nut/nuts. You can't do that with the ring bonded to the spindle.

.

Exactly that ^^^

MichaelG.

As they say! ^^^^^

Thread: Degreasing
10/09/2019 14:51:36

I've used white spirit on similar items, just doused them in a plastic bowl, left to soak then aggressively attacked with an old paintbrush. Paraffin would probably do it as well and smell more pleasant.

Neil

Thread: To Pin or Not To Pin
10/09/2019 14:49:35

The function of the pin is to stop nagging doubts in a corner of your mind

Neil

Thread: What Did You Do Today 2019
10/09/2019 14:46:59

Replaced two of the turbo hoses on my car, one was split.

Now I think I need a skin graft, a blood transfusion and, despite a warm bath and half a box of cleaning wipes, a deep clean.

Neil

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