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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: What lathe to get?
12/02/2012 14:00:54
I take issue with your claim that it has a limited speed range

No VFD on the ex-work one, but IIRC it only had 8 speeds & wide variations between them ? I no longer have access to the machine (so cannot check to be certain) but I do recall having to run faster or slower that I wanted to on occasions. (A quick Googling says 12 speeds, 40-2500 rpm, but "our" machine has been modified by it's original model engineer owner to run more slowly. 28 - 1750 rings a bell but, as above, I can no longer check for certain). So maybe my original comment was not altogether warranted.

Price drops on Chinese imports of this size used ? Seem to hold up pretty well on Ebay - probably helped by the quite large price increases on the new ones in recent years. A Warco BH600 has gone on today - will be interesting to see how it goes !

The difficulty with used European machines is getting a decent one (i.e. one not flogged to death in industry) for reasonable money.
Thread: Imperial/Metric?
12/02/2012 12:28:07
Its good to read how times have changed.

Sadly, nature has a way of moving things along !

In another 10 years time, I suspect that the Imperial stalwarts will be in the minority (on this side of the Altantic, anyway) as those taking up home workshop activities will have had little or no exposure to Imperial measurements in education or employment.
Thread: What lathe to get?
12/02/2012 12:20:11
Whats wrong with link belts?

Great at slipping - not so good at driving ! Even when bow-string tight.
 
May be down to the modern, slippery plastic link material - the original belts were more of a canvas-like construction. Had similar problems on a grinder project at the last employment, where link belts were recommended for smooth running. Yes, they ran smoothly, but the spindle stopped when a load was applied !
 
I have, once, seen a Vee belt that could be split. It had a series of holes perpendicular to the driving axis & was joined with short steel link plates (placed inside & outside the belt) screwed together through the holes. I was unable to track down a supplier, unfortuately.
12/02/2012 10:58:14
DRO also eliminates backlash issues.

No it doesn't - the backlash and many of it's effects are still present. "All" the DRO will do is allow positioning to be set independant of any wear or backlash that may be present in the leadscrew.

Which lathe ? Looking for a machine of M300 size I'd buy a new Warco / Chester Chinese machine - belt drive or geared according to pocket depth. Reports on these machine suggest reasonable build quality & good accuracy. The come fully equiped with chucks & steadies - ready to run "out of the box". Any "issues" - they are covered with a warranty.

If you were to splash out a 3 times or more greater sum on a new M250 or M300 you would still be getting an imported machine, as the manual Harrisons have not been made here for many years.

FWIW I didn't like using an M300 - the one we had at the last employment (which was a mint ex-model engineer's machine, never used in industry before we got it) had a restricted speed range & the dual reading dials on cross-slide & top slide robbed them of "feel".
The well-worn Harrison 140 it replaced was a nicer machine to use.
 
I have no experience of "small" Colchesters - a long bed Mastiff at work was nothing special, though. And a former supplier was less than impressed to find his new "Colchester" was actually a Colchester-badged TOS at a premium price.

An ex-education Boxford might be a reasonable bet - if you can find a later style one (they do not appear to be thick on the ground !).
I would not discount an earlier Boxford if you could find a good one - though the CUD I started with was plagued with belt slip problems on the awful link belt final drive demanded of passing the belt through the bed casting. An ME10 or VSL-L00 would be my preference (though the VSL still has the link belt).
 
Emco Maximats (V10, V11) have always looked good to me, but seem to come up rarely. When Mercer Bros. in Cleckheaton were still with us (much missed), I regularly hankered after the new V11 they had is stock. Way outside my budget, unfortunately.
 
A Super 7 does most of what I require - the spindle bore restriction being my only real gripe. I do have the ability to take any larger stuff I may want to do in to work, though (up to a metre diameter chucked, or 600 dia x 3.5metres between centres if required !).
 
£0.02
 
Nigel B.

Edited By Nigel Barraclough on 12/02/2012 11:26:24

Thread: Imperial/Metric?
11/02/2012 15:24:33
I think people sweat the metric/imperial stuff too much. For me, metric is easier, for others, inches. All they are is measurements; the real challenge is to make things, not to worry about units.

Agreed.
 
Just missed metrification at school - I did all Imperial, my 18 month younger brother was all Metric.
 
Apprentice training & early work experience was mainly Imperial - later work was mainly Metric.
 
Currently I work almost exclusively Metric at home or work, using a mixture of Metric and Imperial machines (in the case of my Taiwanese FB2 clone assembled from two different sources - both on the same machine !).
 
My measuring stuff is also a mixture of the two units, though I find Imperial mics easier to read than Metric (I find I can "loose" half a millimetre too easily on the Metric mics).
 
Any Imperial dimensioned jobs that come in to work are all re-dimensioned Metric - although all the CNC machines can be set & programmed Imperial, fewer mistakes are made if everything is made in the same units. Half of the operators are Polish/ Slovakian - Imperial confuses the heck out of them !
 
The "40 thou to a millimetre" approximation works well to get close & a Poundshop large digit calculator stuck to the cupboard over the Super7 does near-instant accurate conversions as required. Somewhat bizarrely, I tend to think in millimeters down to 1mm, but find it easier to "visualise" sub-millimetre increments in "thou" !
 
Regards,
 
Nigel B.
Thread: Announcement from Arc Euro Trade Ltd.
11/02/2012 14:07:27
Ketan,
 
I can appreciate your reasons for doing this, but from this visitor's point of view it will be another reason not to bother attending.
 
As I have no real interest in steam models of any flavour, or model boats etc. my main interest is in the trade stands. As the cost of attending gets ever greater, the ability to offset some of the cost by not paying postage charges helps justify attending. It is also an advantage to be able to compare the quality of similar items from different sellers "in the flesh" - price alone is not necessarily a good indication of quality.
 
For me, Harrogate last year was a disappointment. Fewer trade stands, more model boats, much the same stuff seen pretty well every year on the club stands - not much incentive to go this year already, before a pre-notified reduction in the trade presence by someone I have previously bought items from at the exhibition on a bit of a "spur of the moment" basis.
 
 
£0.02
 
Nigel B.

Edited By David Clark 1 on 14/02/2012 16:42:35

Thread: Digital Readouts
06/02/2012 20:23:51
You can use the capacitive scales with a Shumatec DRO350 DRO550

Hi Les,

I was aware of the Shumatec displays, but it (they) seem expensive for supposedly "budget" units.

Only the original (and now obsolete, according to the Shumatec site) DRO350 kit is available from MEDW at around £150 posted. MEDW suggests that the board for the 550 is only available from Shumatec in the USA, but they show no availability. The Shumatec site gives a description for a "budget" DRO375 but, again, no details of availabilty or price.
 
I have not followed the ins & outs of the DRO350 project but, IIRC, there were some "issues" with it that were only cured by the 550 re-design ?
 
As a comparison, a "Budget " 3 axis console from Allendale is £156.50 + delivery - assembled, ready to go & warranted - just add glass scales or the magnetic alternatives (which worked out more expensive than glass scales for another project at work - replacing Trimos capacitive readouts on a tool pre-setter. But they were easier to fit in the space vacated by the Trimos arrangement, so purchased anyway).
 
The 3 glass scales do add another £380 or so for my mill, though, where the equivalent capacitive scales from Arc would be around £80. If the DRO350 is reliable, it might be worth considering - whether or not my soldering skills are good enough to build it reliably is another matter !
 
Regards,
 
Nigel B.
06/02/2012 16:19:48
You can still use a vernier and the rotary scales on your mill for more accurate work.
 
you can use your machine dials for perfect accuracy
 
You think your leadscrews are "perfect" ? Precision ground ballscrews are not "perfect" - let alone acme screws on budget machines !
 
Near as I can tell, the X axis screw on my Taiwanese FB2 clone is out by around 0.002" per rev of the screw. This is better than the last one, which I measured at 0.003" error per rev.
 
That is on an 8TPI screw. I have a stainless steel capacitive scale fitted to that axis, which checks out as accurate (as near as I can measure) to slip gauges. The scale clearly shows the dials on the leadscrew to be consistantly inaccurate i.e. take out backlash, set dial & scale to zero. Wind on exactly 1 rev of the screw - scale shows 0.127". Adding another rev comes up as 0.254" etc. Ignorance was bliss - hadn't twigged until I was checking up on the scale !
 
I have installed an Allendale Budget glass scale setup on a Harrison lathe at work - easy to install & has been working for probably 3 years in an industrial environment without problems. Cheaper than the "big brand" DROs, but still not cheap, though. But I do trust glass scales rather more than the capacitive stuff & the installation has the advantage of not eating batteries, no auto turn-off, pre-settable displays etc. You do get what you pay for !
 
Regards,
 
Nigel B.
 
Thread: Lidl cast steel vice-16.99
04/02/2012 14:27:42
Don't trust anything from Lidl. Aldi or any of the cheap s%t sellers

Rank generalisation.
 
I use Lidl & Aldi screwdrivers, spanners & Allen keys for work - no issues with wear, breakage or fit (spanners & Allen keys). Maybe not quite as comfortable to use as "big brand", but they do tend to stay in my toolbox whereas the "big brand" items grow legs and walk off. Likewise HSS step and cone drills last as well as industrial supplier's items, but at a fraction of the cost. Digital calipers have checked out within the usual limits for this type of device when checked against slip gauges - no worse than some branded items costing 5 times more.
 
And both Aldi and Lidl have honoured warranties without a quibble or wanting the defective items returning (Aldi multimeter - replacement couriered from Salzburg (!), Lidl laminator element expired after 2 years 10 months - replaced without question).
Thread: Suggestions please Vol3
31/01/2012 20:03:42
Would something like this Ebay 250981106884 do what you want ? Geared up 1:3 from the leadscrew to read out whole millimetres. The listing doesn't say whether or not it counts both ways - might be worth asking the seller, but cheap enough to experiment with.

Regards,

Nigel B.
Thread: Small Milling problem
30/01/2012 19:15:15
I just had a look at a tool site and the smallest they sell are 3mm

Try another tool site - endmills & slot drills are readily available down to 1mm.
 
We use these (the coated variety, mostly) at work :
 
http://www.cutweltools.co.uk/files/ww/3%20flute%20slot%20drills.pdf
 
Very good service - most ex-stock & delivered next day. Imperial sizes are available too.
 
The 1mm ones do have a tendency to break just for the fun of it, though !
 
Regards,
 
Nigel B.
Thread: Static phase converter plug wiring
29/01/2012 15:13:26
As I understand the output from a static phase converter has two 'good' phases and a third phantom phase-does it matter which phases from the motor are connected to the L1 L2 L3 ? As I understand L3 is the phantom phase.

I have a Clarke PC20 static conveter. The manual for that device states that L1 and L3 are the "good" phases to be used for contactors etc. This device has no neutral connection (4 pin socket). If you have no requirement for a contactor (which would need to be 415V), then connect the 3 motor phases to L1-L2-L3 in any order. If the motor runs backwards, reverse any two wires.
 
Normal "old" colours were red-yellow-blue for the 3 phases, though - black was neutral. Are you sure you have a 415V 3 phase motor ? Maybe open the terminal box to check that the black wire is actually connected to a phase ?
 
The manual for the Clarke PC20 can be downloaded from here :
 
http://www.machinemart.co.uk/download/PC20-40-60-PHASE-CONVERTERS.pdf
 
Regards,
 
Nigel B.
Thread: Myford ML7 Scrape
29/01/2012 14:22:07
Hello John,
 
Glad to hear that you are making progress.
 
I wonder if your machine has had it's bed reground at some point, making the shears thinner than standard. That would be a possible explanation for you having to reduce the width of the insert - I had no probems with mine, which is an ex-school machine that has not been reground.
 
To align the apron, slacken the screws holding the apron to the saddle. Position the carriage as close as possible to the tailstock end of the bed and, with the apron screws adjusted to be just lightly in contact, engage the halfnuts to centre the apron with the leadscrew. Tighten the screws. Aligning the apron with the screw at a position close to the end bearing (where it is well supported) will prevent excess loading on the leadscrew in operation.
 
The rack can be adjusted too - if it is too tight in mesh with the pinion, loosen the screws & move the rack within the cleanace of the mounting holes.
 
It may be worth checking the width of the front & rear shearsat several places along their length - your comment about "tightening towards the tailstock end" suggests that, most probably, the front shear is worn. This will probably affect the tailstock alignment at different positions along the bed - the effect could be alieviated by pushing the tailstock towards the rear shear while applying the clamp.As the inside edge of the front shear was previously used by both the saddle and the tailstock, this is the face I would expect to be most worn - the inside edge of the rear shear less so, so it should still provide a reasonably accurate location for the tailstock.
 
Regards,
 
Nigel B.
29/01/2012 10:11:42
Scraping is the removal of small amounts of material - typically to "fine tune" mating faces.
 
For flat faces, a flat scrape like this one on Ebay ( 160724504712) is used - honed to a very keen edge regularly in use on an oilstone.
 
In use, the part requiring adjustment is "marked" - the reference face is coated with a very fine layer of marking blue (like this Ebay 300654878603) and the part to be adjusted rubbed along the blued surface. High points catch the blue and are visible - the scraper is used to shave off the blued points. A light rub wiith fine wet & dry "denibs" the scraped surface & the process is repeated until the part requiring adjustment "blues up" evenly across the full surface and aligns as required.
 
It is quite a slow process - the amount removed depends upon how much pressure you apply to the scraper and the angle you present it to the surface. Fitters I have worked with who scraped regularly knew how much they took off - typically 3 or 4 scrapes per thou on cast iron -more on soft materials like PTFE slideway liners & less on steel. I don't scraped regularly & generally faff around so take more scrapes per thou !
 
Curved and triangular scrapers are available for scraping bearing bores, and carbide insert scrapers are available for heavier work. A Swiss company - Biax - makes powered scrapers for production use. Some fitters I know prefered to make their own scrapers from flat files for working on steel or bronze - they hold a keener edge & work better on "slippery" materials, apparently.
 
There are references (including YouTube videos) of scraping an the internet - Google is your friend ! But it is a skill only really learned through practice.
 
HTH
 
Nigel B.
Thread: Lathe turns convex
26/01/2012 07:58:53
what do you mean by "fast side"
 
Sorry to have used jargon. This term seems to be a term pretty well universally used by machine tool fitters from the (now mainly disappeared) machine tool builders from the Halifax area.
 
The "fast side" on a slideway is the fixed or reference surface that guides the slide on the shear (face on bed). It is the face opposite the gib strip, and is usually arranged to take the forces applied to the slide in normal operation.
 
So, the "fast side" on the cross slide is the face nearest the spindle, the "fast side" on the compound is nearest the centreline & the "fast side" on the saddle is (in this case) a section underneath the saddle the bears on the inside edge of the front shear on the bed,
 
The addition of a strip to use the rear face of the rear shear has caused no problems with my saddle lock & I cannot see how it would. Yes, you back off the gib screws to allow the strip to be fitted. The gap appears to have been originally designed to be 1/16", so there are no adjustment issues with the gib & the apron lies where it was intended also - something to bear in mind if you decide to re-machine the existing "fast side" - the saddle will move forward on the bed & there may not be sufficient clearence in the apron attachment screw to align the leadscrew correctly. You way also have to make a thicker gib strip. This face was most probably gang-milled at the same time as the intended "fast side", so should get you pretty close to original alignment by packing it with a parallel spacer (which is what I found in practice).
 
I used ground flat stock because I had a suitable piece. A flat, parallel brass strip would have done equally well. If I were doing this at work, I would use a piece of a PTFE-based slideway liner like Turcite, Guidecoat or Rulon. When checked with marking blue, my "modification" showed as being flat - normal practice if the face were being scraped would be to slightly relieve the central area (just a couple of scrapes) to ensure that the face bore on two pads at the ends & so would not rock.
 
I suppose ideally a Loctite High Strength Retaining compound should be used to attach the metal strips - I didn't have any to hand and used Studlock. Araldite (slow setting) may also work - that is what I would have used with a PTFE liner. It has been giving satisfactory service for a number of years now. To attach the strip, I slightly roughened both the saddle face & one side of the strip with coarse emery cloth & degreased (brake cleaner), then lightly coated both surfaces with Loctite. A piece of writing paper was folded over both shears of the bed & the saddle (with strip held in place) was placed on the bed over the paper & the gib inserted & tightened to press the strip flat against the bed. This was left 24 hours. The paper prevents any squeezed-out Loctite from glueing the saddle to the bed. After the cure period, the saddle was removed & any excess Loctite and stuck-on paper were removed with a scraper & the flatness and bearing of the new strip checked with marking blue on the bed. Adjust if required with a scraper, clean down, lubricate and re-assemble. Then a final test cut to make sure all is OK.
 
Regards,
 
Nigel B.
 
25/01/2012 19:47:34
I had a similar problem with a Super 7 when I first got it. My machine is mid-60s at a guess & has the "narrow guide" saddle arrangement. With this, the saddle is guided longitudinally on the front shear only, with the "fast side" on the inside of the front shear (shared with the tailstock) & the gib strip bearing on the outside.
 
The "fast side" under the saddle is much shorter than the gib strip - what appeared to have happened on my machine was the gib had been adjusted too tightly at the tailstock end of the saddle, which is actually outboard of the end of the fast side & had caused excessive wear. This caused the saddle to be skewed on the bed - easily checked with a set of feeler gauges in the gap between the saddle and the rear face of the rear shear. The gap should be equal (and around 1/16" IIRC). You may find that it is not equal (smaller towards the tailstock) & this will cause convex facing. (I guess that the person who overtightened the gib strip was the same person who greased all the saddle oil points !).
 
I "fixed" my machine by effectively doing what Myford eventually did with their "wide guide" arrangement - I Loctited a piece of ground flat stock (1/16" x 1/2"x full length of casting IIRC) onto the outer vertical face on the saddle, so that the "fast side" is now the ground flat stock bearing on the previously untouched rear face of the rear shear . The saddle now bears on the outer edges the bed & does not share a guide face with the tailstock . This also has the advantage of making the fast side equal in length to the gib strip and so gives a greater bearing area. After doing this, the lathe faced correctly (very slightly concave) & no further problems have arisen.
 
HTH,
 
Nigel B.
Thread: Stress relieve in castings.
25/01/2012 18:43:47
The bed castings for the older 3 Vee bed Boxford lathes were "weathered" for 6 months before finish machining. There were pallets of bed castings around the works yard, and they were copiously watered daily witha hosepipe (when it wasn' t raining or snowing !).
It was not unknown for some of the workforce to "water" them as need arose, either !
 
After 3 months the castings were shot blasted & "topped and tailed" - rough planed top and bottom - then put oustside for another 3 months of "weathering". After another sholblasting, they were filled and painted before finish machining - bottom planed & top "gang-milled" to produce all the vees, flats & sides at one pass on a very robust Russian-built duplex head horizontal mill.
 
The later hardened bed machines were just being developed & put into production when I was there. The bed castings for those came in "stress-relieved" from the foundry - no "weathering", they went straight from the delivery to production. There were some "issues" with the beds moving during machining. The beds had the top formation gang-milled as with the older machines, then they went on to a fixture on a new Snow grinder with a Radyne induction hardeneing plant mounted at one end. The bed passed slowly under the induction hardening device, which locally heated a small area to bright red heat, which was immediately quenched with coolant. After hardening, the grinder table was moved under the wheel for grinding the top formation in one pass, the wheel being dressed to shape by a special diamond dresser.
 
I seem to recall that the trial beds were not straight & the "old hands" were keen to blame the stress relieved casting - no substitute for weathering ! The answer, if I recall correctly , was to pre-stress the bed by tightening a clamp in the middle of the bed (with a torque wrench to apply a repeatable load) before hardening. This clamp was released before grinding. Result - straight beds without weathering.
 
I have - somewhere - photos of this hardening & grinding process. I got a Praktica MTL3 SLR for my 21st birthday & one of the first films I exposed though it was around the Boxford works. This was April - May-ish 1981. Seems a long time ago, now !
 
Regards,
 
Nigel B.
Thread: MEW 186, Best ever issue
20/01/2012 13:37:56
G17
M3 S1000
G0 X-9.2669 Y5.8091
G0 Z0.18
G1 F100.0 Z0.0
G3 F150.0 X-6.7691 Y3.7682 Z-0.0031 I1.4063 J-0.8278

Martin,

How was this created - CAM program ? No tool call, no tool radius compensation suggests so, but Z moves incorporated in G3 moves (with no K value?) suggests a helical move ?

In my case I am to old to learn to use.
 
Dick,
 
May be to old to want to learn, maybe ? I can understand some of your positioning regarding using manual machines, the challenges that using them pose and the satisfaction gained doing so., but I am pretty sure that you could learn more modern methods if you had a reason (or desire) to do so. In nearly 30 years of teaching machinists to use CNC controls, I have not come across any (regardless of age) who could not get tp grips with it in the 2 or 3 days allocated - even the ones who were anti or belittled their capabilities at the start of proceedings Doesn't mean to say that you should change doing things how you do them for the sake of it, though !
 
I was suprised to get issue 186 though the door this week, as I cancelled my subscription at issue 184. More involved articles on CNC would possibly make me want to subscribe again. The "half way house" solution to part automate a lathe appears (to me) to be a solution looking for a problem - reminisant of an all-but-useless Harrison Alpha lathe we mistakenly bought at work. All the "diasdvantages" of a manual lathe & few of the "advantages" of a full-blown CNC solution.
 
£0.02
 
Nigel B.
19/01/2012 21:44:15
I'd forgotten about solar power. But (serious question) is it capable of supplying enough power to run moderate sized equipment?

Standard installation by "A Shade Greener" on my roof is a nominal 3Kw - most I have seen on the energy meter attached to the output from the grid tie inverter is 3.1 Kw in summer. This time of year it peaks at around 1.7Kw on a clear day. A bit of high altitude cloud drops that to 500/600 W - heavy overcast it's down to around 200 W. Total generated power per day varies between about 3Kw/hrs on a truly dismal day in winter to over 30kW/hrs in the height of summer. This is on a south facing roof in West Yorkshire.


Only trouble is I mainly get to play in the workshop in an evening ......

Regards,

Nigel B.
Thread: collet holders???
17/01/2012 13:13:38
I have a Taiwanese built FB2 clone & use 2MT collets direct in the spindle.
 
I have used ATF in the gearbox, without any issues.
 
Regards,
 
Nigel B.
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