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Member postings for mgnbuk

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

Thread: Aircraft General Discussion
25/04/2018 08:33:08

Or, given Sam's location, possibly CAC Wirraways.

**LINK**

Thread: Warco WM250 Lathe and Warco WM18 Milling machine (Advice please)
24/04/2018 14:42:45

To check if the quill is perpendicular to the table, proceed as follows :

Fully extend the quill and clamp it.
Mount your magnetic base on the table & set up a dial gauge to bear on the front of the quill as close as possible to where it exits the head casting. (You may need to use a finger clock to get close to the top of the quill & so be able to check over the longest distance.)
Clamp the head to the column.
Using the X axis (table moving left - right) "wipe" the dial gauge across the quill and adjust so that the needle reads zero on the high point. (Note that you may get a different reading depending on the direction of movement - just remember which way you were moving to get the zero when you take the next reading.)
Unclamp & raise the head such that the dial gauge reads close to the bottom of the quill (don't touch the dial gauge !). Reclamp the head.
"Wipe" the dial gauge across the quill again & the error is the highest (or lowest) reading on the gauge at the high point on the quill when moving in the direction that you set the initial zero.

Then repeat the process, but with the dial gauge set on the side of the quill & "wipe" it with the Y axis (table moving front - back) rather than the X.

The readings "should" be pretty well the same top & bottom from both setups - my guess is that the side value will be close & the front value will be out.


If the column is perpendicular to the table in both directions (as you suggested earlier) & the quill isn't, that suggests that the quill bore isn't parallel to the rotating joint face at the rear of the head casting. This could well be the source of your front to back tramming error.

HTH

Nigel B

Thread: Where to get a running bearing for Ajax AJ8 mill
18/04/2018 12:41:13

**LINK**

1 1/2" Od x 1 1/4" Id x just over an inch long hardened & ground inner bearing ring.

Press or glue 2 onto a 1" bore x 1 1/4" Od sleeve & away you go.

Quite a range of Imperial bearing inner rings readily available - precision ground hardend parts at reasonable prices

Nigel B

18/04/2018 09:01:57

What about using needle roller bearing inner ring(s) ?

**LINK**

May need to use more than one is series, but I don't think that would cause problems.

Nigel B

Thread: Anyone fancy a larger UK made milling machine?
11/04/2018 16:12:02

Seriously, do they normally machine steel dry,

Yes. IIRC one of the reasons being that the inserts need to be kept at a fairly constant temperature, so coolant needs to be a very strong flood. This is not always possible & is difficult to both guard & collect. Intermittent application of coolant to hot inserts can lead to failure due to thermal shock. Again IIRC, the idea is that most of the heat goes into the swarf, but I have regularly come across operators keeping a pair of welding gloves to hand to change tools, as the tool bodies can get hot enough to burn you. Insert drills, though, need high pressure through-tool coolant to blow the chips out of the hole - that really does go everywhere !.

the Mandelli factory in Piacenza in the late 1980s, they were capable of such work rates that it was refrigerated before re-use.

That may have been to keep the workpiece cool to maintain tolerances. I have seen some machines that use temperature controlled coolant circulated through the machine to keep the machine structure cool for that reason - including through hollow ballscrews via rotating unions. As Mandelli were manufacturers of quality boring machines, I would expect that they took dimensional accuracy of parts seriously.

Nigel B

11/04/2018 13:39:24

I'm not sure that the "UK made" bit is true anymore - pretty certain they announced in the trade press that they were not going to be building their own machines here anymore & were going to be concentrating on the agencies a couple of years ago.

Nigel B

Thread: Faceplate or Independent Chuck?
24/10/2017 07:35:34

If you accept the 'minimum two threads engaged' rule

I work to the " jaws fully engaged in the body with no overhang" rule wherever possible - "two threads engaged" is a new one on me & way outside my comfort zone.

How would your capacity calculations work out for full jaw engagement, Neil ?

Nigel B

Thread: John Stevenson
23/10/2017 20:30:20

Sorry to hear of John's passing.

My condolences to his wife & family.

Nigel B

Thread: Faceplate or Independent Chuck?
23/10/2017 20:27:09

Surely the 4.5 kg mass of the 6" chuck, especially if compounded by an off-centre workpiece adding to the centrifugal forces, be more than the headstock bearings and motor power are designed for and would put great strain on these items. The C3 mini-lathe is probably not designed to take anything bigger than the 100mm (4" chucks.

A standard mini lathe appears to use 6206 deep groove ball bearings fpr the spindle. If you have a look at the ratings for a 6206 bearing, you will see that you will not have an issue with overloading them. A heavier, larger diameter chuck will be advantageous when doing interrupted cuts - it is a large flywheel & will help both the gearbox & the (relatively weak at low revs) motor under such conditions - mini lathe owners on other forums have fitted 5kg 5" 3 jaw chucks without problems & report better finishes using these..The heavier chuck does take longer to accelerate & decelerate, though. But if you feel happier with the smaller chuck, go with your feelings (just watch your digits if you run it with the jaws protruding !).

Not sure what MG means with regard to MB's picture - as the jaws are inboard of the 6" chuck body OD, the jaws are not running in the gap - a Myford will swing 7" over the bed after all. The jaws are running over the gap area, but not in gap.. That configuration would run without fouling on a C3, which also swings 7" over the bed.

Is that a tumbler, MB ?

Nigel B

22/10/2017 16:13:28

the jaws are still going to hold the same size whether they are overhanging a 4" chuck or in a 6" chuck that isn't overhanging.

But the job held in the 4" chuck will not be as secure, due to less of the jaws being supported by the body and less screw engagement. Also, the overhanging jaws will not be visible when the chuck is rotating - potential for an inadvertent operator / moving jaw interface - the operator always comes off worse in such situations. Certain lessons drummed in at Apprentice Training School 40 years ago still resonate !

I think 6" is too big for Colin's lathe.

A C3 mini lathe swings 180mm, according to the Arc website, which is 7.08" - or about the same as my S7. A 6" direct mount fits a S7 fine, so should also fit a C3 fine, though the body will be closer to the bed due to the lack of a gap.

Nigel B

22/10/2017 15:18:50

You aren't going to be able to open the jaws of a 6" chuck very far on a 3 1/2" centre height lathe...

But you can open them to the edge of the chuck body - extending jaws beyond the extents of the chuck body is generally regarded as bad practice *. And opening the jaws to the OD of a 6" chuck will allow larger pieces to be held that doing the same on a 4" version.

Nigel B.

* and yes, I know we all do this at some point and to some extent, but that doesn't make it any less bad practice !

22/10/2017 14:31:03

4 jaw independent, as large as you can fit (probably a 6" & slim body you can get one to fit to minimise overhang.

Used to hold square, rectangular & irregular shaped objects, not just to set off centre. Also used to accurately centre round items - more accurately than a 3 jaw self centring chuck can usually manage.

Faceplates more for special setups, like using a Keats angle plate **LINK**

or to hold castings that don't lend themselves to holding in a chuck. The mini lathe faceplates seem too small to be useful to me (space needed for clamping arrangements), plus the cast slots seem very wide & rather short.

I have the 7" & 9" faceplates for my Myford - not used either in anger yet, but use the 6" 4 jaw regularly. The advice to those starting out who could only afford one chuck initially was to go for a 4 jaw independent over a 3 jaw self centring. Might take a bit more setting up on round work, but more versatile.

Nigel B

Thread: New chinese lathe or old Myford lathe
20/10/2017 18:14:43

When I was initially looking for metalworking capabilty at home (some 25 years ago), my first thoughts were to go for one of the Chester lathe mill combination machines that were advertised in the motorcycle magazines. Seeing one in the flesh at a classic bike show was a bit of an eye-opener - there was so much play in the various moving parts it felt worn out straight from the crate ! At the time, this was pretty well the only mainland Chinese machine available for the hobby market, with the other affordable (relatively !) small machines being Taiwanese or East German. My thoughts changed to a CT918 lathe - basically an Emco Compact 8 & still available until recently from Chester & Warco. - and the saving began.

My father had bought a Boxford CUD from one of his customers - he didn't particularly want a lathe, but the seller wanted rid of it and the pillar drill Dad really wanted in one transaction.. After it bit him (thou shalt not start the spindle with the chuck key still in the chuck ...) it got no further use. When he passed away, I bought the lathe from my brother (who continued to run my father's business for a while & the machine was a company asset.).for a nominal amount.

A mid-'60s ex-school CUD that had ended up in a clothing manufacturer making press stud insertion dies, it was not in bad condition, but had been greased through all the oiling points. So it was completely stripped, cleaned, repainted & rebuilt. Over the course of a couple of years, I managed to get most of the missing change gears, a direct mount 6" 4 jaw chcuk, faceplate, QC toolpost, a boring table (the lathe was pre-tee slot cross slide) & a travelling steady - never did manage to find a fixed steady. This was pre-Ebay, so the bits came from dealers, Auttjumbles & ME exhibitions. It worked mostly quite well & was accurate, but the under drive was a pain. As the final drive belt has to pass through the swarf tray, it has to be a link type belt. The original that Boxfords used was of a canvas-type material & that worked OK-ish, but was in poor condition. The new types are made from a plastic material & slipped badly under load depite being bow-string tight.

Skip forward a couple of years & I was on-site at a machine tool dealer fixing a machine that the company I worked for at at the time had retrofitted a replacement control to. They had a pretty clean, mid-'60s ex-school Myford Super 7 - direct mount 3 & 4 jaw chucks, faceplate, catchplate, taper turning attachment & 3 sets of change gears (there must have been 2 more lathes somewhere else gearless !). My milling machine fund was depleted to the tune of £825 & it came home with me a couple of days later. My thinking at the time was that I would get it cleaned up & use it, determine whether I prefered the Boxford or the Myford & sell the looser. The Boxford went. For what I wanted to do (and still do for that matter), the Myford was nicer & more convenient to use (speed range, ease of speed setting & the spindle clutch particluarly). Selling the Boxford & accessories raised far more than the Myford cost, so the milling machine fund was reinstated.

I found a fixed steady at an Autojumble a fortnight later (never did find a Boxford one) & a couple of years later bought another (poor condition & damaged) Super 7 B of similar vintage to get the feed gearbox. The gearbox was swapped to my lathe, parts that were beyond redemption on the "scrapper" were purchased new direct from Myford & fitted to my machine, with my good-but-slightly-worn bits intended to go into the other. A friend wanted this machine after I had done it up, but he died suddenly before I finished it & I lost interest after that. It went as parts on Ebay, raising more than it & the new parts had cost - effectively a free feedbox , leadscrews & nuts on my machine.

Used machines, as has been said, are a lottery & the quality of the Chinese competion has come on leaps & bounds since I looked at the Chester Multi-purpose machine 25 years or more ago (and shuddered !). The newest "original style" Boxford will be 30 + years old now & they were not made in the quantities that the Myford 7 Series machines were, so availability is not as good. Finding accessories at a reasonable price (or just finding them period) was a chore over 20 years ago & doesn't seem to have got better. Find a nice, fully equipped machine & it may be a better buy than a Myford or a new Warco etc., but if I were to start out again I would probably go the new route. Had I bought the new 918 I intended to had fate not intervened, I would most likely have made more "stuff" and spent less time rebuilding !

Nigel B

Thread: Flexible Ratchet spanner challenge
20/10/2017 10:53:55

Local Aldi today were "remaindering" a set of 5 or 6 flex head ratchet spanners (from 8-19mm AF IIRC) for £4.99 the set - 3 year warranty too. Quite a pile of them to shift. As SWMBO was with me on this occasion (car in for looking at) I was forced to resist !

Nigel B

Thread: Micro Bearing Question
15/10/2017 10:23:44

**LINK**

How about ceramic bearings ? A quick Google for a spec on a ZrO2 696 bearing from one manufacturer gave an operating temparature of up to 250 C and 12000 rpm when oil lubricated - other makes may give different specs. & alternative lubrication regimes may help increase the operating speed.

HTH

Nigel B

Thread: Embarking on a metal planer/shaper design+build
14/10/2017 16:13:26

This publicity / education film by Waldrich form, at a guess, the 1950s gives a good look at the machines & the operation of their hydraulic feed system. **LINK**

The film commentary is in German, but it isn't hard to work out what is going on if you don't know any / much German.

Capable, versatile machines that have been, largely, lost from UK workshops, with nothing to replace them in many cases.

Is the "cubic metre" the total envelope of the finished machine, or the workpiece volume ?

Nigel B

12/10/2017 20:08:04

"It would be brilliant if we could see some metal planers and shapers in action; "

You are about 20 years too late to see that easily - and they were getting thin on the ground then

"but remain in use in industry."

Barely. This one is currently for sale local to me. **LINK**

This is one of the last I know of - 2 of the 3 the others I used to have work done on have been scrapped over the last 10 years or so & I would not be suprised if it failed to find a buyer & was scrapped also. Even assuming it got a bid at the start price, it would most likely cost at least as much again to get it dismantled, moved, a foundation put in & re-installed. The Waldrich linked to was actually the smaller of the two planers at that company, so I guess that the larger Craven has already been scrapped. I dismantled a Swift Summerskill planer for scrap where I work now about 5 years ago - it was worth more as scrap than it would have sold for intact. There was nothing wrong with it & I felt guitly about having to kill it, but we needed the space for another machine that would make money. Planer tables fitted with legs & used as marking out or assembly tables come up in auctions quite regularly - every one a dead machine. At one time they were sent out to India , but that market largely disappeared when the indian Goverment put large import tariffs on used machinery to encourage Indian industry to invest in new machines rather than buying obsolete used ones.

I wonder why the lecturer set this task, as universities have been teaching that planers & shapers are obsolete for at least 25 years - I had to work with a placement year engineering student over the acceptance of a rebuilt machine that long ago & he brought in one of his course books on machine tool technology that dismissed planers in half a page, with a line drawing & one paragraph. Maybe beacuse the students would be unlikely to come across one in real life & have to work out how they worked from scratch ?

Nigel B

 

Edited By Nigel B on 12/10/2017 20:08:25

Thread: Denford Triac Mill
05/10/2017 15:17:50

Sounds like your mill has a Coventry Easy Change toolholder

MSC Industrial Supply carry these **LINK**

Make sure you are sitting down before looking at the prices !

Nigel B

03/10/2017 19:37:35

I believe all Triacs were fitted with steppers in std form

Not all of them.

I have an ex-industrial Triac that is different to those shown above - it is on a twin pedestal base, with a removable swarf bin between the legs, with the gas strut balanced, full width lift up front guard. The electrical cabinet is full width across the rear on the pedestals. Control system was a Heidenhain TNC355 (operator station mounted on a swinging arm from the base), with brushless servo drives (can't recall the make, but not "main stream" to all axes. Spinde is BT30 with an Erickson locknut & no ATC. Spindle drive is a 2.2Kw squirrel cage motor directly connected to the spindle with a polyvee belt - it originally had an IMO inverter drive. The machine was bought in to scrap for the electronic parts where I used to work & I bought the carcass for £100.

The Fanuc Triac shown above would also have had servo drives - type dependant upon the exact model of Fanuc 0M fitted (the "A" models were analogue interface, "B" & " C" models were all digital & could only use Fanuc's own brushelss servos).

I really should make room in the garage to get it out of storage - it's only been there 11 years now ! I have the stepper motors, stepper drives, PC break-out board & an inverter already bought in to get it up & running again. I planned to remove the rear mounted cabinet to save floor space & cut out the side of one of the pedestals to let in a smaller box (also already to hand). Unfortunately the lift-up guard & the swarf bin had already gone out in a skip before I got the OK to buy it.

Have fun with yours,

Nigel B

Thread: Saddle play when direction of cut is changed in my ML7
07/09/2017 09:19:37

Presumably regular gib strip in front side of saddle need to be shaved a bit to widen gap on the back. Probably unused shear will need scraping to provide better bearing surface. What do you think about it?

It didn't on either count when I did mine. There was enough clearance in the apron screws to get the half nuts engaging correctly as well (slacken apron screws, engage halfnuts as close to the end of the screw as possible, tighten apron screws).

Rather you than me

Indeed. It took me two months of lunchtime sessions where I last worked to do the top of a Super 7 bed that had around 0.008" wear. Milled the vertical faces on a large Zayer bed mill as a "test cut" after it was rebuilt & retrofitted after a fire.

Nigel B

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