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Member postings for Kiwi Bloke

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

Thread: ML7 spindle and bearings
15/10/2020 00:19:36

With reference to Hopper's experience and knowledge, I would suggest that, for a Myford, shimming a well-scraped bearing 'to provide oil clearance' is wrong. Let's have a debate!

The ML7's spindle bearings will rarely if ever be working as true hydrodynamic bearings, so the added clearance is unnecessary and just leads to chatter - particularly under conditions of high radial load, at low spindle speed. Also, shimming changes the bearing's shape, rather negating the care taken when scraping.

Thread: Temperature control when grinding HSS tool-blanks?
15/10/2020 00:11:20

I bet a fair proportion of forum members never dress their grinding wheels. A loaded or blunt wheel will heat the tool tip much more than an opened-up, dressed wheel. Fine wheels are more prone to this, hence Peter G Shaw's observation. Also, keep the tool moving across the wheel, where possible.

Thread: Grumpy old men
11/10/2020 11:35:10

Stupidity.

Thread: Bleeding hydraulics
09/10/2020 10:43:40

OK, I'll stop worrying. It's obviously not a significant problem in practice.

However, the thought of a log-splitter with a lot of air in the system is frightening - all that stored energy to be released as the log 'pops'! Some of my eucalyptus logs go with a final bang, as the stress in the splitter's frame is released.

Thread: Whitening
09/10/2020 10:33:37

Emgee - no doubt you're right. I thought the novel principle that Chaddock brought to the problem was heat-setting the rings. My understanding is that this doesn't produce a perfectly-shaped ring, necessitating final skimming, so Trimble's approach may be a bit lacking.

What rankles, however, is the credit given to Johhny-come-lately, Trimble. It's like the electric light bulb. Edison improved it and made it practicable, but he didn't invent it - that was another British invention.

Thread: Bleeding hydraulics
09/10/2020 10:17:13

Thanks everyone for your advice and warnings.

I'm sceptical that air will work its way out in a reasonable time, either as an air-oil foam or as air bubbles: the dead space in the cylinders and pipework is quite large, compared to each cylinder's stroke volume. Some fluid exchange will of course occur, but there'll be a lot of shunting backwards and forwards, and the air will surely find its way to the high points - in this case, behind the seals, I appreciate the system will (sort of) work as an hydraulic/pneumatic system, but the pipe lengths are very different to each side's cylinder, so there would likely be different degrees of 'compressability' on each side of the loader's arms.

I plan to (try to) pre-fill the cylinders and pipework, before re-installing the cylinders. I have plumbed in Tee unions at the input to each cylinder, so can use these as filling/bleeding ports. I can move the piston rods manually, to use the cylinders as pumps, with a bit of added grunting. I take the warning about the danger of bleeding under pressure, but I can crack open the diverter valve, so there's a substantial pressure drop across the valve, and be careful not to allow the circuit to be working against load: i.e. bleeder open and cylinders at minimum stroke.

If any of this sounds stupid, please let me know!

It sounds like I may be over-thinking this. It's a bad habit. Perhaps that's why I get so little done...

07/10/2020 21:58:20

Not exactly model engineering, I know, but there's such a wealth of knowledge and wisdom here...

I have had to replace the seals in the rams of my tractor's front-end loader. The single-acting rams are arranged with the cylinders pivoting on the frame fixed to the tractor, and the ram rods extend outwards and upwards, to lift the loader arms. The hydraulic seal is at the 'open' end of the cylinder, the seal bearing on the rod. There is no provision for bleeding.

The cylinders always point upwards, to a variable degree, thus any air in the system will rise to the seal area, potentially making the seals run 'dry', apart from any oil carried to them on the surface of the moving rod.

I can't see how it's possible to be sure there's no air in the system. The inside of the cylinders (luckily not working surfaces) have rusted a little, suggesting water and air (mayonnaise?) have contaminated the hydraulic oil.

Local tractor engineers say they never attempt to bleed such external hydraulic systems, after they have been opened - 'the air just works its way out'. I think this is Kiwi 'She'll be right' engineering - dangerous! The only way out for air in the cylinders would be past the seal. Is this likely?

Whilst I'm fairly sure I can arrange things to get the system air-free (it will be a bit of a performance), I'd be interested to know what 'proper' engineers would do about such an hydraulic system that has been made with no provision for bleeding.

Thread: Whitening
07/10/2020 21:35:54
Posted by Emgee on 07/10/2020 17:31:15:

Jerry Howell provides some details of various methods at this link:

**LINK**

From what I have seen over the years most use the Trimble method.

Emgee

Another (prettier) version of Howell's article: **LINK**

'The Trimble method' gets bandied about quite a lot, particularly in the USA. Prof. Chaddock (Loughborough, England) described 'the method' in 1967, long before Trimble's article in Strictly IC - in the '80, IIRC. It's difficult to believe that Trimble was unaware of Chaddock's writings, but his article made no reference to what had gone before. Let's give credit where credit's due - it's 'the Chaddock method'. Of course, Trimble was an American...

Thread: Ball bearings and friction.
02/10/2020 09:20:56

Ah, now I've seen a couple of videos, I understand the problem. I was thinking that only small arcs had to be accommodated - as in a complex-pendulum harmonograph. Clearly flexures aren't appropriate for multiple complete-circle rotations. Not very bright to offer a solution before understanding the problem... [shuffles off stage, head hung low].

02/10/2020 08:32:51

Avoid bearings altogether by using flexures, i.e. threads, wires, etc?

Thread: WHY THE TANG?
17/09/2020 11:02:26

I think this subject has already been done to death, but, before this thread dies...

What Hopper has written is undoubtedly true. Apart from anything else, in industry, it's too much to expect that every drill taper will be un-bruised and clinically clean, and every socket will be cleaned before the bit is inserted, so the tang is a 'safety' device, taking over driving duty, should the taper friction fail, and thereby stopping relative movement between socket and bit. A scored MT socket is a sad sight, and would most likely not have been produced had there been a back-up tang to prevent the rotation of tool within socket. You tend to see them on milling machines, where there is no provision for locating a tang, because a draw-bar is expected.

Of course, if there's a foul-up of sufficient violence to twist the tang to bu**ery, all bets are off, but we'd never do that, would we?

There's also the 'Use-M-Up' (or something like that) sockets that used to be / still are available to drive damaged MT drill bits (the end has to be modified). Evidence that a tang-like end can drive sufficiently well to be useful.

Edited By Kiwi Bloke on 17/09/2020 11:10:46

Thread: scraping technique
17/09/2020 10:50:26

Well one good reason for not blueing the workpiece is that, at the end of a scraping pass, you would end up with a mess of scraping swarf mixed in with blue, which you would have to clean off, before removing the burrs. You'd also have to clean the plate. Doesn't sound like a pleasant process. Another reason is that it would not be easy to achieve a well-controlled blue film thickness, particularly in awkward places, such as dovetails.

Thread: Sumitomo insert identification
14/09/2020 05:24:31

Hi Jon, in the early '90s, there was a chap called I R Rivers, trading as L B & S C R, in London SW12. He used to demonstrate Sumitomo tips and tooling at the Model Engineer Exhibition, and sold a small range, by mail order. Your holder is listed in his catalogue. He listed the following tips for it: CCGM 32XEFM (0.1mm tip radius), CCGM 320EFM (0.2mm tip radius), CCGM 321EFM (0.4mm tip radius), all in T12A grade carbide, a robust, general purpose grade, which worked exceptionally well - you could throw blue and smoking chips all over the workshop, working at what then seemed ridiculous feeds and surface speeds, and also take very light finishing cuts, all with excellent surface finish.

Ian Rivers faded from the scene, and Mr Carter appeared, I suspect for not very long, around the turn of the millenium(?).

I haven't looked at a Sumitomo catalogue for ages, but would not expect any of these holders or tips to be listed. I believe that Sumitomo's tips and holders, then in production, did not respect the ISO dimensional standards, and, by the late '90s, Sumitomo had fallen into line with the rest of the manufacturers, producing ISO-compliant tips and holders. Someone please correct me if this is wrong. This was bad news indeed for those of us who had invested in their tooling. Grrr!

Thread: Someone with a recent Cowells ME90 lathe
09/09/2020 11:04:30

Hello Renaud.

The driven pulleys on the countershaft: 73.99mm, 57.62mm.

The motor pulleys: 26.59mm, 45.09mm.

These diameter measurements are across the 'top' of the Vee (max. dia.) and are by digital calliper. Access to the motor pulley in situ is a bit awkward, so say give or take 0.02mm.

Good luck with your modification!

Thread: Hydraulic ram machining
23/08/2020 09:08:24

Nicholas, I admire the skill of your contractor. I suppose I could grind a hole reasonably round in 1/8" thick stock, but some of the pivot bores are in considerably thicker stock - and they have to be co-axial with the hole on the other side of the rod or cylinder. Rather than building up the walls of the worn hole, I was thinking of welding in a 'tube' - like a very thick-walled bush. Lower skill level required!

NDIY, good idea. The trouble is that the pin should have an anti-rotation snug (or whatever), and, whilst I can machine the pins, getting them heat-treated just adds to the expense and hassle. It all starts to get difficult...

Having looked at the thing in more detail, I think that the loader offends me so much that I just don't want to spend the time, effort and money on the ghastly thing. It will always be crude and ugly. There are more important and urgent things to attend to, let alone the things I'd really like to do. As a friend sagely pointed out, one's time may be running out far more quickly than one's money, so buy your way out of hassle, if possible. Well, I'm terminally tight, so I think I'll do a bare minimum lash-up fix, cross my fingers, and walk away, whistling.

Thanks again, everyone, for your ideas - all appreciated.

Thread: Workshop Equipment
23/08/2020 07:22:06

Hello and welcome Mx Davidson (Stuart, Pauline, whatever - we don't mind...).

One thing to consider is where this journey is going. Are you likely to be constrained by cash and/or space so that your workshop will contain a lathe, drill, and little else, by way of machines, or will you be able to equip the 'shop with a milling machine? Don't forget the cost of all the tooling required...

The Myford lathes have their limitations, but, when well-equipped, can provide unparalelled versatility and can tackle jobs that seem far too big for the lathe's nominal size. Oriental lathes don't have gap beds, and seem to have a very limited range of accessories available. So, you buy a lathe, cheaply, but that's it.

The support from the various outlets seems to be very variable. Search the forum and draw your own conclusions about support. Quality control can be a problem with these cheap machines, so you need to be sure that a problem will be handled honourably by the seller.

I favour second-hand, because I can bring machines back to spec., however that requires a decent level of equipment already, of course. There's a decent Myford ML7, well-equipped, that's just popped up on www.lathes.co.uk, at a sensible price. The point previously made about ex-industry machines likely being clapped-out is true, but most(?) Myfords will have been in private ownership.

Thread: Hydraulic ram machining
23/08/2020 06:03:25

Thanks everyone for the information and links. All very useful and thought-provoking. It sounds encouraging too, if I decide to make new rods. Having now removed the loader from the tractor (a multi-gorilla job, but actually done by wife, self and swearing), I'm wondering how to proceed. The loader is badly designed, poorly executed and horribly worn. Previous owners clearly didn't posess a grease gun.

My preference for precision and things being 'just so' has to be weighed against the sheer difficulty - and expense - of restoring the horrible thing. All the pivots have worn their pins considerably, but the 'bores' (to dignify an 'orrible, irregular oval hole with an acceptable engineering term) should really be attended to. That would seem to require a magnetic drill and Rotabroaches (neither of which I have) to hog out the metal around the hole, then weld in a replacement hole (anyone tried to weld a hole?) - you know what I mean...

At some stage, reality has to be faced. I think I'll replace the seals and the battered rods and leave the pins and pivot holes as they were. It can only be an improvement on what it was before, and it's likely to outlast me - unfortunately... But it offends my desire for, if not perfection, doing the job properly.

Any further thoughts, however, would be gratefully received...

20/08/2020 10:27:13

Hi folks. Has anyone here any experience of machining the chrome-plated, centreless-ground rod from which hydraulic ram rods are made? Will tipped tooling (or even HSS) cope with the chrome layer, and without peeling it off (assuming it's well-plated, of course)? And what about drilling and boring? The 1 3/4" dia. rod needs a 1" diameter cross-hole at one end. T'other end has an axial 5/8" UNC threaded hole, about 1 1/2" deep. (Imperial units because it's an old fella). This end of the rod should also be faced and tapered so it can be inserted past the seals without damaging them. It's a pretty simple job, but the material may be a difficult opponent.

The only grinding facility I can throw at the job is an angle-grinder, with an old bloke behind it.

I'm contemplating machining this (these?) myself (on a big, borrowed lathe - the rods are 37" length overall), because the cost quoted by a local reconditioner / manufacturer made me sit down smartly - and involuntarily. On the other hand, the raw material may be horribly pricey here in expensive NZ, so perhaps the quote is reasonable. The catastrophic failure of my tractor's front-end loader (well-loaded at the time, of course) was spectacular, although not actually dangerous, thank goodness. Wife and dog know well to stay clear of anything attempting to defy gravity.

Thread: Emco FB2 Quirks and Additions
02/08/2020 10:56:22

Thanks Gray, very helpful - I don't remember considering experimenting with adjustment of the 'slotted grub screw'. I must dig the table out and play...

Your other comments (and the manual) lend more evidence to my suspicion that Emco didn't consider the thing to have been designed for arcuate milling. What an odd oversight. However, Emco seem to have had other surprising design blind spots - the Unimat 3 vertical unit's quill spindle bearings (sloppy and unadjustable) and the early Compact 5's cross-slide feedscrew nut being integral with the table (no adjustment possible), to name but two.

I'm eagerly awaiting further details of your FB-2 enhancements...

Thread: Lathe turning speed in relation to different metals
01/08/2020 08:07:39

I'm sure you can find more than enough explanation in books - remember them? However, in the home workshop, what works is what matters... Suck it and see.

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