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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: TurboCAD 2015 Pro
17/08/2015 18:18:21

Garry,

Neil did not actually sat he wanted them as pdfs in his first post, and I don't consider my reply to have been negative. You can alter the font, text size etc of a dwg without redrawing it, starring again from a pdf is asking for errors to creep in

17/08/2015 13:01:51

Why would you go for paper or pdf, both of which require redrawing, when it is already in electronic format? Seems like a waste of someone's time to me, and introduces possible errors. I appreciate this doesn't help you in this instance. Input once, use many.

dxf usually works, at least between turbocad, autocad and draftisight

Thread: Collet Chucks on the Lath
12/08/2015 23:54:07

If you make the drawbar out of a piece of pipe you will be able to hold long lengths of small stuff

Thread: Surface for Needle roller bearing
09/08/2015 01:24:16

you can get 18mm OD, 25.5mm long, 15mm ID from

http://simplybearings.co.uk/shop/Bearings-Needle+Roller+Bearings-Needle+Roller+Inner+Rings/c3_29_35/index.html

just make a 15mm OD 10mm ID bush and press it in If you really can't cope with the excess 0.5mm on length someone with a surface grinderv will be able to take a bit off.

Thread: Large copper tube ...... Where.?
09/08/2015 01:17:54

Be very wary of stainless. The stuff used in the nuclear industry is likely to be austenitic (at least it was in the bit I worked in), and this is prone to chloride stress corrosion cracking and to pitting when used stressed in very hot water. You can get SS suitable for boilers, but you have to be really sure it's the right stuff. If you can't afford copper use mild steel, and get your coded welder mate to weld it together. You might need material certs as well, ask your club boiler inspector

Thread: Surface for Needle roller bearing
07/08/2015 21:14:56

you can buy rod specially made for running bearings on from

http://www.bearingboys.co.uk/Linear_Shaft-3782-c

it's pretty hard so depends how much machining you need to do. I seem to remember that it's surface hardened only

Thread: Steel spec
31/07/2015 19:52:20

I'm not asking for a copy of the cert, just tell me in the advert is it EN1, EN1a En3 etc. This costs nothing. GCQ is meaningless.

30/07/2015 20:39:47

Can one of the suppliers out there explain why they are so reluctant to tell us what grade of steel they are selling? I've just bought some described as GCQ, which seems to mean 'good commercial quality'. I asked a proper steel stockholder, and he reckoned it meant 'I've lost the certificate'. Presumably model engineering suppliers buy in quantity from stockholders, and in my experience a reputable stockholder will always give you a certificate, most of them whether you want it or not, it's part of their QA procedures.

Thread: Threads ME vs BSW
28/07/2015 22:37:13

5/32 BSW and 5/32*32 ME are identical, as are 1/8 BSW and 1/8 * 40ME

Thread: Simple CAD software.
24/07/2015 20:10:09

Turbo cad does not work if you want to export it to the laser cutting men. If you import turbo cad drawings into Autocad (which is industry standard) the ends of the lines don't meet up, this might be the reason laser cut software won't have it. I use Draftsight 2D, can't fault it.

Thread: Tiny grinder
20/07/2015 18:15:59

This covers your lathe bed with grinding dust. Horrible. You'd have to cover everything with cloths before you start and then e very careful when you take them off.

I have a cheap <£20 grinder, fitted with decent wheels and rests it does all I ask, and can be taken outside for dressing, or stored under the bench.

Thread: Phosphor bronze vs SAE 660 bronze
16/07/2015 11:41:46

It's all a matter of how much lead. Colphos is 4% lead and the manufacturer states it is OK for silver solder. PB1A (old spec for leaded bronze) is I think 7% lead. The British Standard stated that it could only be silver soldered with special measures. I think the problem is that the lead boils out and contaminates the silver solder, but that might be rubbish. Drawn PB1 doesn't have lead, but is a right pain to machine, it closes up on the drill. Cast PB1 is OK but not that easily found in small sizes.

Despite this the Australian model boiler code says leaded bronze is OK for bushes, but I wouldn't risk it.

Thread: EN24 Heat Treatment
15/07/2015 18:14:06

If you're applying the load to these bolts via nylock nuts, then the thread in the nut is going to strip long before EN24 breaks. To make life easy can you make up two saddles with long bolts through them then just use HT bolts?

Thread: Gudgeon pin steel
14/07/2015 10:55:52

Case hardening changes the chemical composition of the surface of the steel, you then harden it by heat treating (ie dropping it in water from red hot). It's all a matter of definition

12/07/2015 22:15:14

you can't make mild steel harder by heat treating it. You can case harden it, but not the leaded stuff. If it has threads on it you'd be better casing before cutting the threads, then hardening (case just increases the carbon content, let it cool very slowly). Other way is to copper plate the thread, then it won't case. If using silver steel, temper it well down, you don't want it snapping. I'd be surprised if mild steel wasn't good enough without hardening. It's very easy to replace if it eventually wears.

Thread: 10-32 UNF Threaded Rod
08/07/2015 22:27:37

If you are making fairly long lengths of thread it is worth either screwcutting and finishing with a die, or making a die holder to fit in the toolpost and driving it along at 32 tpi. Just cutting with a die is prone to pitch error, doesn't matter for short lengths, but can be problem with deep tapped holes. Once you've made the holder it makes the job easier, and you have it for next time

Thread: Carbide Cutting Tools for Flexispeed
05/07/2015 20:31:44

I should have said sharpen it after the first cut!

05/07/2015 18:21:47

If you only have fairly low speeds then carbide is difficult to justify on small lathes. High speed steel is sharper and you can put more top rake on which reduces cutting load. Top speed on my old ML7 was about right for 1/2" EN1 steel cutting with HSS, so about right for 2" with carbide, but you possibly then I didn't have enough torque available. Learn how to sharpen HSS, it's a lot cheaper. I can only endorse previous comment on tangential tooling. Brilliant. I use it for machining staineless.

Brazed carbide is good for machining cast iron if it has hard spots, otherwise I used HSS, just sharpen it again after the last cut. I now have a more powerful higher speed lathe, and do use insert carbide, but not all the time, and certainly not on interrupted cuts

Thread: spanners and nuts
27/06/2015 21:05:06

I thought the reduction is size was a wartime economy, so 1956 should be post that

Thread: Heat Treatment Oven
26/06/2015 17:28:13

Melters usually use induction heating, all the current carrying stuff is cool (even water cooled sometimes). No I'm not offering to design one, way out of my league, but I've been involved in projects using them. Quite fascinating watching the metal melt for no apparent reason. I suspect this is outside amateur use, the power requirements were prodigious

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