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Member postings for duncan webster

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

Thread: Man management
12/07/2021 23:05:19

When I built my last house extension I had to get the design approved before I started and the Building Inspector would come round at pre-arranged points in the build to inspect what had been done. Sounds a bit bureaucratic, but he was actually very helpful. As I understand it that's all gone, and builders get to mark their own homework. Result, all these unsaleable properties with built in defects.

Thread: How important are odd-sized milling cutters? (Clarkson vs ER)
12/07/2021 20:12:39

?? my 3/8 BSW stuff fits in the horizontal as well, and it has a captive drawbar

Thread: Shock at low pay for high skill
12/07/2021 17:02:12




Edited By duncan webster on 12/07/2021 17:04:10

Thread: How important are odd-sized milling cutters? (Clarkson vs ER)
12/07/2021 15:21:58

If you have a captive drawbar, which is what centec is designed for, you can't get a mt2 with tang in. If you cut off the tang you then can't get the mt2 out, no slot in mandrel. You could have a non captive drawbar and use a rod down the hole to bump the mt2 out, but far and away the best is mt2 with tapped hole for drawbar and a captive drawbar

12/07/2021 12:30:30
Posted by William Ayerst on 12/07/2021 11:01:52:


I have realised that if I use Clarkson, I won't be able to drill with my existing drill bits, or ream with my existing reamers (unless they fall into those precise measurements).......

Get a jacobs chuck mounted on a 2MT arbor with a drawbar

12/07/2021 11:58:03

I don't know where that drawing came from, but 1/2" BSW won't go down the spindle on a Centec VH, at least not mine. 3/8" is the biggest, it won't even accept M10. If I were starting again I'd look into getting the hole opened up, as 3/8" BSW stuff is getting increasingly rare. Don't panic, you can still get it.

ER25 is big enough for a Centec, will hold 16mm cutter. The only drawback with ER vs Clarkson is if you are doing a big cut with the side of the cutter they can tend to draw out with ER, but Centec isn't that sort of machine.

Thread: Power feeds for Chinese mills
12/07/2021 11:42:34

Many moons ago I made a drive for the Naerok miller using a DC motor and a train of gears. This had two disadvantages:

  1. When the cut started and more load went on the motor it all slowed down, by quite a lot, in fact if set for a very slow feed it would just stop.. I can wax lyrical about why, but not here
  2. you had to disconnect the drive to do manual feed.

I overcame the first by incorporating a feedback loop. I suspect people using windscreen wiper motors just have a lot of oomph to spare so it doesn't slow down as much.

The setup on my Centec uses a stepper with tooth belt drive. It is so much easier. If you use one of the pulse generator things referred to above it is just buy some bits, make up a mounting bracket, join the bits together and go. No need for a clutch, just wind the motor round. No need to know anything technical about steppers or controllers. Mine is a bit cleverer as it incorporates acceleration ramps

Thread: Shock at low pay for high skill
11/07/2021 23:49:43

I can't get worked up about a skilled machinist calling himself an engineer. I have quite a few letters after my name, but I wouldn't pretend to even have a clue about driving (for instance) a horizontal borer, especially cutting an internal thread. Similarly I'd be quite worried if the horizontal borer guy set about doing the sums for designing a bridge. And yes I do realise that some highly skilled shop floor guys will move into the more theoretical roles.

Many moons ago there were sandwich courses, where aspiring graduate engineers did a mix of industrial and academic time, including starting off by at least learning what various machine tools and other processes could achieve. This has always seemed like a very good idea to me, Unfortunately I wasn't made aware of this until too late, but on leaving university I got myself a shop floor job. Only basic stuff, and not for very long, but it has been immensely useful over the years, especially when some production engineer was trying to pull the wool over my eyes.

What does get up my nose is the "sales engineer" in the shiny suit with the company car who goes around agreeing with the customer to supply something that can't be made within the timescale or cost quoted. Then he gets a bonus for increasing sales and the poor engineers get blamed for being over budget and time.

Would I advise my son to go into engineering? Well I did, and he's doing well. What's not to like about using other people's money to make whizzo machines

Thread: Blown Bricks : Advice please !
11/07/2021 23:26:52

There are various grades of brick, classified by frost proof ness. see bricks (despite the same name, I have nothing to do with the brick company!) Not that this helps now. Your only answer is to dig the blown ones out and replace with better bricks. This might look a right mess unless you can get something that matches, but as others have said it's not technically that difficult. Not getting mortar all over the face of the brick is the skilled bit

I think the strength of the mortar is more to do with accommodating slight movement of the foundations, if the mortar is weaker than the bricks the mortar cracks and you can remedy it by pointing, if the other way round the bricks crack. as you have said some bricks have blown without seeing any mortar

Thread: Bearing Location - Pulley or mounting block
11/07/2021 20:33:39

Whichever way you do it, the bearings should be a light push fit in the bit that goes round, ie on the shaft if the bearings are in the block, or in the pulleys if t'other way.

A purist would say that the bearings will last longer if in the block , but either will see me out, so I wouldn't get worked up about that.

Thread: Garmin sat nav
11/07/2021 11:49:26

The main purpose of a sat nav is to avoid nuclear war in the car. SWMBO is incapable of {or unwilling to} read a map whilst the car is moving. Her best performance was to announce I'd have to stop and read the map whilst we were on the Peripherique, the Paris inner ring road. This makes the M25 look like a country lane. I'll let you know how the battery upgrade goes.

10/07/2021 23:39:59

Ok I've bought one, just concerned at its odd behaviour

10/07/2021 23:05:08

I think the battery in mine is kaput, if left unplugged for any length of time it would then take a very long time to recover and switch back on. I brought it in and left it plugged in to a USB port on my computer. It recognises that this is not the car as it has data lines (they are connected with resistors in the car charger). Whilst plugged into the computer USB it displays a message to say so. Now even if I unplug it that message stays on, even plugged into the car, and even more strangely the on/off button doesn't have any effect.

I've tried connecting it to the Garmin software on the computer, doesn't recognise it

Unless someone has a bright idea it looks like a hand in pocket job. I'm not impressed, it's not that old (out of warranty)

Thread: Lathe gear calculation
09/07/2021 01:30:03

Nigel, you should look at Calum's link, it sorts out the gears to cut tpi, if you want metric you have to convert it yourself. 1mm pitch is 25.4 tpi. It will work out 26 tpi just a quickly, or even 27 if you were so inclined

Thread: How to turn this bush
08/07/2021 12:27:16

I think delrin swells when subject to prolonged immersion, so don't make it too good a fit

Edited By duncan webster on 08/07/2021 12:27:40

Thread: Nose piece
08/07/2021 00:41:56

Well here's one at least, 2 minutes on ebay MT2

and here's another, doesn't say 3/8, but the engraving on the photo suggests 94AAOSw1cNaM8i7">another

and Chronos do MT2 split collets with 3/8 drawbar, but I'd steer clear, very easy to get them stuck

08/07/2021 00:14:29

You can get mt2 er25 collet chucks with 3/8 bsw drawbar. Not common I'll grant you

Thread: Lathe gear calculation
07/07/2021 22:23:16

Callum, pm sent

Thread: Pop device
07/07/2021 20:50:09

Super Soaker has more range

Thread: advice old British motorcycle
07/07/2021 20:44:20
Posted by Windy on 07/07/2021 19:50:20:

I had a memory recall in 2019 a young couple of speed nuts took me to Burton on Trent to look at some old BSA bikes.

He bought a BSA C10 a 250cc side valve for £2600 it was the same model that was my first motorcycle mine cost £10 in 1959

I sold mine 35 years ago for ~£100. Awful machine, no power, handling like a banana. I think they were nicknamed 'grey porridge' which just about sums them up

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