Member postings for Brian Wood

As a relative newcomer, may I just say I would probably still be unaware of the clever work Graham Meek has done with screwthread cutting. I stumbled across it only from this forum.

There is perhaps much that could be improved in the software, my recent inept attempts to add pictures might have been only my fault, but the process was clanky and without any guidance; mis-step once and it all disappears without any hope of retrieval.

I think the forum does serve a purpose for information exchange and ideas, you can be selective in chosing items to look at, unlike the moderators who have to wade through everything. There are new converts to the hobby perhaps only because of these pages.

So on balance it would be a loss for it to go, following John's course would surely just wipe the slate clean by dumping all that has gone before and then finding different bugs in the new software just as irritating as the present ones. .

Brian

Edited By Brian Wood on 18/02/2013 09:31:53

Thank you Wolfie, it looks all the better for it too.

Brian

Neil,

My father-in-law found it after the war and dismantled much of it. It was packed with anaeroid bellows in pairs on balanced beams, pipes all over the place, lots of gearing and shafts, all cross pinned and running in bushed diecast frames and so on.

Truly a box or wonders. I really have little idea what compensated for what, but airspeed, altitude, estimated ground speed and cross windsheer would all have played a part in accurate bomb release . The piece I've described struck me as instrument precision workmanship, a tricky thing to get right anyway and all made in vast numbers at a time of enormous pressure.

Brian

Edited By Wolfie on 17/02/2013 13:37:42

Gentlemen,

The spiral form is very clearly milled, starting with a plunge cut at the closed end. The finish is too good to be left at that, it has also been ground so that motion to the bronze carrier is still possible from the run out end of the thread where side forces have more effect. Under a good lens I can see the witness marks of the milling at the start, and moreover, the ground acme form seems to been achieved by angulation of the stone; the bottom of the groove finishes in an inverted Vee

Thank you Clive and Keith for your observations, I had no idea such could be achieved on a lathe.

Brian

Edited By Wolfie on 17/02/2013 13:36:45

Hello Michael and Bazyle,

I finally managed to get the photos to load, it seemed to want to handle them one at a time, Part of my trouble is that I don't have a 5 year old in the house to show Grandad what an old fool he is! The result is I'm afraid both messy and bitty.

I don't know which non-linear form the thread is, it might well be trigonometric. Would it actually make much difference to the process of producing it? I rather doubt it.

I'll see what develops. Thanks for your interest

Brian

Edited By Wolfie on 17/02/2013 13:32:02

Hello Everyone,

I have puzzled on and off for years on how the guidance form was machined 70 years ago without the benefit of today's CNC methods

These components were made in ten's of thousands in the USA. It it superbly made and finished, the thread form has I think been ground after milling. The barrel is 1/2 inch diameter and the groove is 29 degree ACME form.

My question is how would you go aboutdoing this using mechanical methods alone to form the logarithmic shape, there must be amongst the forum members plenty of experience. I have my own ideas, but it would be interesting to see what the rest of you think. There should be 3 photos if I've pushed all the right buttons.

Brian

Hello Steve,

Welcome aboard, nice to have a new contact.

It seems to me that your question has been largely submerged in the confusion over moderation, [ I don't understand the order of service either] and only Springbok has made any attempt so far to address it. The reception over the Kennet T&C grinder could just be typical of an Editor's response to a rewrite---- 'It's been done before' Few authors will be tempted to submit material, however up to date, when they know that is the likely outcome, and previous authors might feel their stuff is just being copied and rehashed..

I suggest you trawl the Digital archives and Workshop series books for ideas that you can adapt to your machinery; it will be a good learning exercise anyway and give you the satisfaction that your version of the gizmo does it s well as the author's.

Machine specific devices will add a new layer to the challege as your knowledge and skills grow. Read a few well written books as well, it all helps. One thing will soon become apparent is that the bulk of it has been done before, a perfect example is in the motor restoration article in MEW 200 with inboard disc brakes dating to 1935..

Use the grey matter and forge your own track!

Brian

Edited By Brian Wood on 14/02/2013 12:07:12

Hello Swarf,

Thank you for pointing out my mistake, it is the cross-slide that is guided with the degree of cut controlled by the tposlide as David says.

Sorry for the confusion

Brian

Hello Neil,

I am like you in wishing to get the best from my hobby interest and at a realistic cost, but this thread started from comments on Aldi purchases that were 'a bit bent and crunchy' and 'maybe not very accurate'

The point I was trying to make was that fundemental measurements are made with these tools and it should not come as any surprise to find they frequently don't work as one might hope. It is possible to get better without paying a King's ransom for it and for gear that will last a lifetime if cared for.

I get huge satisfaction making my own equipment where I can or modifications to suit my purpose and knowing you can trust the measurements is a part of that.

Brian

Hello Rick,

I am not familiar with 13x40 lathes, nor a taper turning attachment to fit one, so I can only offer some general advice

First of all, the attachment mounts onto the lathe bed, NOT the saddle. Most are based on a dovetailed guide that can be locked to different shallow angles by bolting at each end into its mounting brackets, The dovetail will guide a block that is then attached up to the saddle via a stout coupling piece and a bracket onto the rear of the saddle so that guiding movements are directly into the saddle.

NOTE You must disconnect the normal saddle feedscrew arrangement so that all the saddle motion is from the taper guide alone. Failure to do that will result in a full on jam and damage to all sorts of things.

There should be a number of machined mounting points on the rear of the lathe bed upon which to mount the attachment, these may take the form of a fully machined surface running the full length of the bed, or a number of individual pads as on Myford lathes. There will be threaded mounting holes to match the spacing in the attachment you have bought. After fitting the attachment it will then be parallel to the bedways both across the lathe and vertically to within fairly tight limits in each direction.

The attachment should have come complete with all the bolting needed, and the stout block to transmit motion from the guide upwards to another substantial bracket or fitting that bolts to the saddle.

If you have all that then you are partway there. Taper angles should be engraved on one mounting for the guide so that you can preset for small angles.

The range of mounting holes along the rear of the lathe will allow you to make tapers at variou positions along the bed by moving the attachment to each section.

Take a look at my photos of the version I made for my Myford, it has all the essentials I've just outlined, but it is a full length version and not mounted as the genuine Myford version. which is about 8 inches long.

I hope that gives you some help. They are interesting things to watch in use.

Brian

Jon,

Moore and Wright sell quality calipers at a much more attractive price than you quote for Mititoyo, I was lucky to get some 1/2 price [£25] at the Harrogate Show 2 years ago from the Allendale stand, they were flying off the shelf at that.

Much better made than the cheapos.

This thread does though remind me of the much larger debate ongoing on precision vices. Pay rubbish price, expect rubbish. Why waste the time and trouble?

Brian

Like Pete I have followed this thread and in some places with concern or at least amazement. The common sense expressed by Pete was a refreshing change, long may it be so.

I have made the same painful discoveries for myself and as a result have haunted bankrupt stock and industrial tool sales to be able to buy better quality at prices I can afford, usually with success.

It is good to back your judgement at these events too, you quickly learn who is knowledgable and who is just a scrappy on the hunt..

Brian.

Further back in this thread was mention of Titanic being let down [no pun intended] by inferior rivets, and blaming that on the accountants. That may not actually be true, but this story is.

In the later stages of Rolls Royce's readying of the RB211 big fan jet engine for service [late 1960's] a very expensive cock up was laid directly at the door of the bean counters.

The compressor drum on these engines is made up from many discs in titaniiun alloy,. electron beam welded together at the narrow rim sections a little below the fir tree roots holding the blading. The process is carried out in a vacuum chamber and superb welds are the result. To prevent beam impingement onto the weld on the far side of the drum a sacrificial backing plate catches any 'blow by'

Unknown to the team at RR, after successful trials, plain mild steel backing plates were substituted in an attempt to save money instead of ordering the expensive titanium alloy versions. The result was that production drums were welded up and contaminated on the inside with a brittle eutectic alloy of 40% iron and titanium which was undetectable by both elecrical and magnetic methods.

It was found by chance to rust easily and that was the only way of reliably sorting out the rogues. I believe the entire batch were scrapped since chances could not be taken. The cost ran into millions taking lost lead times into account as well as scrapped materials .

Brian

Some while ago I worked PT for a local firm of agricultural engineers. One of the team was a student from Leeds working towards a degree in engineering. He got his practical experience with our firm since the Health and Safety rules had closed workshops at the college.

Very early on in my time there he asked me to show him how to fit a hacksaw blade, to be more accurate, which way round it was fitted.

I later spent quite a lot of time showing him how to hand sharpen drills; I could understand that since it doesn't come easily, but to be close to qualifying as an engineer without the very first of basic practical understanding and knowledge worries me. He is proably directing jobs on site now.

Brian

Edited By Brian Wood on 09/02/2013 16:33:25

Surely the easy way in a lathe is to use a tool at centre height and run it down the cylinder as a scriber?

This assumes of course there is clearance available for the carriage to clear the cylinder..

Brian

I think Chris and Graham sum it all up properly. Another good reason for doing things that way is to prove a point or principle to others who don''t or can't grasp the concept and need to be won over.

Brian

Hello again Andy

I have a friend, Myford ML7 owner x2, living in Chandlers Ford Easteigh who might be prepared [if asked] to look it over. Is that close enough to you?

Brian

Hello John,

I can't help you directly, but others might if you put some pictures on the post so that they can see for themselves, your description is confusing. They were made in fair numbers so someone should know.

Brian

A good suggestion Chris, but you run the risk of getting a dealer in who will want to have it for himself to sell on and make money from it

Select your valuer with care!

Brian