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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: 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.
Thread: Mill Misalignment
14/01/2012 10:30:03
Can anyone think of another cause?

You have checked that the column is square to the table in both planes before doing a trammel check, haven't you ?

I see a great deal of reference to trammel checks in ME circles, but very rarely any reference to checking that the column is square beforehand.

As an extreme example - if your column was set to 45 degrees to the table and the spindle could be adjusted so that it trammelled true to the table, it would still trammel true when you changed the height of the head on the column, but the position of the spindle relative to the table would be different..

National standards specify the sequence of alignment checks - levels first, then squareness / straightness of the major elements, then spindle alignments / runout / trammell.

Regards,

Nigel B.
Thread: lathe query
12/01/2012 20:46:58

After the cross slide was attended to the saddle was rebedded using Epoxy bearing material.... Search for MOGLICE and you will get the idea. However i used my own mix (Posted on this site under epoxy bearing material.)
 
Good luck using that method - I hope that it stays attached to the saddle. Most of the machines using this method that the company I used to work for came across during refurbishment had come adrift from the casting. It looked fine - just a "quick scrape" to get it bedded to the reground bed - but tapping with a file handle would inevitably produce to dull, hollow sound indicating that the coating was no longer bonded to the casting. On some machines the coating could be removed with a wallpaper stripping scraper - it just shelled off. The problem appeared to be oil from the central lube system forcing itself between the coating & the casting where the feed holes were drilled through both. On the only one I remember being attached & re-usable (a Scharmann horizontal borer IIRC) the other "downside" comes in - the stuff is very hard on scrapers due to the fillers in it. We had to get 2 boxes of 10 Sandvik carbide scraper tips for the fitter - while he was using one box, the other box was away for diamond lapping
 
We replaced the coatings with PTFE based tapes. We used a variety - Guidecoat and Rulon mainly, but also a hard white plastic sheet called BiPlast (had to be careful with that one - it wouldn't run without oil & had to have a high surface loading or the friction was very high). We occasionally came across this type of coating that had come un-bonded, but pretty well every Moglice coated machine had to be re-done due to oil induced releasing of the coating.
 
And don't believe everything you read in the manufacturer's bumf about "setting up a saddle on a bed with sealing strips & injecting the coating ....." If you have an hour or two sometime I could tell you about the trials & tribulations of a now long gone UK milling machine maker trying to series produce CNC VMCs by injecting such a coating - but I am not about to do that on an open forum !
 
Regards,
 
Nigel B.
11/01/2012 07:38:38
I was taught that it was to allow two faced-off parts to sit together without rocking - two concave parts contact around the outer edge & sit flat together, whereas two convex parts contact in the centre & rock.
 
Regards,
 
Nigel B.
Thread: Axminster Power Tools milling vices on offer
29/12/2011 12:56:59
what first vice would one choose for a 6" wide table.

I chose a 4" Vertex K4 for my FB2 clone, which has a 6" wide table. It is in reasonable proportion to the machine & is well made. My only gripe (which prompted this thread) is the rather limited opening. If you wish, I could take a photo of it on the machine.

The Axminster VA 4" on sale is a much bigger & heavier (21 kilogrammes) vice all round. Unfortunately, the sale item that was delivered to me before Xmas was of nowhere near the quality of finish of the Vertex product. I am not in the market for another project, so it went back. I did not check the accuracy before it was returned.
 
I have no experience of the Axminster "K4" on sale, but it doesn't look like my Vertex K4
( http://www.vertex-tw.com.tw/products/products_list.php?language=_eng&cid=25 ). It does, however, look distressingly like a very poorly made Chinese manufactured 4" vice we bought at work on "sale" (£20ish + Vat - and overpriced at that !) from Cromwell tools. If we machined more than graphite, it would be all but unusable ! As it is, it gets very little use as it is so unpleasant to use.

Chronos appear to have had a run on 4" vices - when I looked after returning the Axminster vice, they appeared to have sold out of the 4" versions of most models.
 
Regards,
 
Nigel b.
Thread: Is 0.1 deg good enough..
29/12/2011 12:34:55
The machine was of obscure foreign make but superb quality . Construction was conventional - long fixed bed , travelling table and bridge type milling head slides .

That description could apply to Swiss-made Sip, Dixi or Oerlikon jig borers - fantasic quality and accuracy with prices to match. I could only guess that the bed rose sightly towards the ends as a compensation for the mass of the table & workpiece deflecting the bed slightly during travese.

Regards,

Nigel B.
Thread: Precision Levels - calibration
21/12/2011 19:37:40
At my previous employment the levels were sent out annually to be checked over and adjusted as required - bases checked for flatness & burrs - box levels additionally checked for squareness - and vials checked for sensitivity. The company we used - Wharfedale Gauge in Skipton - was taken over by LS Starrett & subsequently ceased general calibration services
 
In use, the level was always checked both ways round to ensure it had not been knocked or disturbed since last use & "tweaked" as descrbed in the Level Developments leaflet you linked to.
 
Regards,
 
Nigel B.
Thread: Power drawbar
21/12/2011 19:26:35
You do not mention the type of holder BT ISO, The old NT, or CAT etc.
 
The basic taper is the same on all of them. At work the Bostomatic is DIN 69871, while the Kira & 2 Cincinnati Sabres (a 750 & a 2000) are BT40. The Correa is a 50 taper to DIN69871
 
Only the DIN2080 form has the parallel stump behind the taper - a Marwin Max-E-Mill we scrapped earlier this year used that (50 taper). That machine came with some DIN69871 tooling that could be used with "special" pullstuds that had the parallel stump included. I have a couple of specialist DIN2080 holders away at a spark eroders having the stumps cut off to allow the tooling to be used on the Correa (which replaced the Marwin).
 
Shizuoka were well built machines - you see them here (UK) badged as Matchmakers, frequently fitted with Posidata stepper motor CNC controls and Summit toolchangers. These used an electric impact wrench on a screw drawbar. Unusually they functioned with DIN2080 tooling, the tool exchange gripper fingers having an internal groove that clamped over the flange, rather than fitting into the vee-grooves on DIN69871 / BT holders. The air-operated change arm "followed" the tool in and out of the spindle as the drawbar was screwed in or out. No drive dogs were fitted, as the spindle could not be orientated.
 
Standard design pullstuds are very cheap here - the tooling supplier I mentioned supplies new from around £4 each.
 
The Berg collets are a one-piece turned part that is subsequently cut in to 4 pieces - with a slitting saw, I presume, from the marks on the edges.
 
My previous employer dabbled (unsuccessfully) with an epoxy aggregate construction vertical borer. Horrible stuff - the Technical Director was no where near careful enough working with the epoxy resin & became sensitised to it - he had to wear light cotton gloves impreganated with special cream for weeks to clear up the skin problems & subsequently only had to get a whiff of epoxy fumes to break out in running sores. Be careful !
 
Regards,
 
Nigel B.
Thread: Axminster Power Tools milling vices on offer
21/12/2011 19:01:38
Fedex delivered to work around 12.30 today - a well packaged, 21kg box.
 
Unfortunately, it contained a dark green painted vice much as described by Paul above. The only ground face I could see other than the jaw plates was the top of the moving jaw & that had savage wheel bounce marks - the other working surfaces being milled. The jaw plates had edges you could shave with. The general paint finish gave the impression that the castings had been dipped before machining.
 
The chromed pivoting handle fitted the screw hexagon fine, but the screw bearing was a poor fit in the casting. I have not come across a milling vice with a fine pitch vee-form thread before. The moving jaw was a very poor, sloppy fit, with gritty oil under the faces when it was moved from the delivery position.
 
It is being collected for a refund tomorrow, on the grounds that it was not as described & did not warrant the "precison" tag. I was offered a "better quality" version of the same design at a reduced price, but was unwilling to take the risk unseen.
 
Very disappointed with this (and told them so), having always had good quality products from Axminster previously . This unit appeared to have been made down to a price, not up to a standard. I will take the opportunity to inspect the offerings at Harrogate next year.
 
Apologies for misleading anyone - done in good faith based on previous experience with the supplier.
21/12/2011 07:46:12
Well, it's due to be delivered today, so I will soon find out ! If it is "not fit for purpose" it will be going back. I'll post the results of accuracy checks when I have completed them.
 
I have been happy with the Vertex K4, which is well made & accurate. If it admitted 100mm rather than 80 I would probably not have looked for an addition - no plans to move the K4 on.
 
Regards,
 
Nigel B.
20/12/2011 20:00:28
If you are in the market for a milling vice, Axminster Power Tools have some on clearance at the moment.
 
4" K4 swivel base vice £38.16
4" VA swivel base vice £52.28
5" VA swivel base vice £57.12
 
The more expensive vices include carriage - if you order before 9 am tomorrow 21st December, the usual £4.95 carriage on the K4 is waived. All prices include Vat.
 
I seem to think that these are Vertex units painted cream for Axminster .
 
I have ordered a 4" VA for my FB2 clone milling machine- the jaws open wider then my current K4, which always seems "just too small" in that regard.
 
To find these, click on the "Clearance offers" banner on the home page - the vices are on page 8 of the the offers. There are some other engineering offers in amongst the wood stuff, including lathes, chucks & collets.
 
No connection with Axminster, other than as a satisfied customer.
 
Regards,
 
Nigel B.
Thread: Power drawbar
20/12/2011 19:37:32
John,
 
I was not particularly advocating using HSK tooling - rather that a home-made solution along the lines of a simplified commercial design could be feasable. For home use, hardening may not be required for a reasonable life & a gauge or two should allow repetative production of blanks within useable limits without too much hassle. I must admit to thinking from my own machinery perspective here - my Super 7 came fitted with the taper tuning attachment.
 
I take your point on ISO 40 tooling being relatively cheap & available - my prefered tooling supplier at work has a standing promotion for 5 off ISO40 ER collet chucks or endmill holders for £99. We frequently buy from auctions & see used toolholders go for more than that !
 
There is a cheap way of getting the benefits of hydraulic operation - air-over-oil intensifiers. Only suitable for "closed" systems with no leakage (so not suitable for the Berg cylinder, which lubricates the rotary union from leakage back to tank), you can get high pressures from shop air. The American milling machine manufacturer Monarch used these extensively on their vertical machining centres for tool release & axis clamping functions. Another (more expensive) version is the Spencer Franklin intensifier, which uses a large diameter air cylinder to push a small diameter oil piston - the "intensification" being the ratio of surface areas of the pistons, with 20:1 being a popular size (2000 psi hydraulic from 100 psi air). Jones & Shipman used these for clamping CNC rotary tables.
 
Disc springs fail regardless of manufacturer, in my experience. We used to de-grease then, spray with a dry molybdenum anti-friction coating (Rocol, I think - around £25 for an aerosol tin) & assemble with molybdenum grease. Some still broke eventually.
 
Regards,
 
Nigel B.
Thread: Is 0.1 deg good enough..
20/12/2011 19:15:31
(REALLY big ones are pretty immobile, whatever happens!)

Well, actually, that isn't the case.

Most really big machines rely in large part on the foundation that they are bolted to for rigidity, as do most quite big ones. Most manufacturers are pretty specific about the foundation requirements (usually specifying concrete density , miniumun thickness & re-enforcement) and the costs of putting in suitable foundations (particularly in areas with poor subsoil) can be considerable.
 
And failure to do do as suggested can result in poor performance - a large re-built CNC milling machine overhauled by my previous employer was not accurate & could not repeat the alignments achieved in the works when re-installed on site. Before the fitter on site got "stuck in" with a scraper to "sort out" the problem, investigations revealed that the customer had not put the machine back on the prepared foundation it had come off & had inadvertently re-located it across a joint in the floor - the column was on one concrete pad, the base was on another & the two pads were moving suffciently to affect the machine alignment. Re-positioning the machine so that it was all on one pad removed the requirement to "correct" the machine alignment "problem" with a scraper !
 
It is apparent that many model engineers are not overly interested in the way that industry goes about building & installing machinery, with the "it's good enough" attitude being prevalent. Some, however, may be interested in "trying to do it right" !
 
£0.02
 
Nigel B.
Thread: Power drawbar
19/12/2011 20:15:11
I have not seen a power drawbar used on a morse taper. I supsect that the force required to break such taper would be large - even the normal steep taper tooling can stick if the tool gets hot in use - some drawbars are designed to contact the head of the pullstud in the last millimeter or so of travel to break the taper free, particularly on toolchanger machines where a stuck tool can damage the mechanism.
 
I have designed replacement spindles incorporating screw type & collet type drawbars. The collet clamping element & cylinder were bought in from a German company - Berg Spanntechnik. The datasheet for the clamping element is here :
 
http://www.berg-spanntechnik.de/wEnglish/produkte/werkzeug/pdf/ssk.pdf
 
This gives details of the spindle internal features required to make it work. We used them with hydraulic clamping cylinders, not Belleville spring packets. More reliable clamping & almost impossible to pull a tool out, as the cylinder features non-return valves that generate a hydraulic lock when clamped. Not cheap. though - IIRC a 50 taper cylinder (3.5T pull) was around £3500 10 years ago. The collet was around £200
 
For the screw type units we used Align Air-power units (same company that makes the add-on power feeds), usually bought from XYZ Machine Tools. Drawback to these is the need for a spindle brake, as the spindle spins when the tool touches the taper otherwise. The tool also has to be guided into the spindle as the drawbar rotates, there is a risk of cross threading & the threads must be kept free from debris & well lubricated (molybdenum grease) or they can seize.
 
During rebuilds of CNC machines we frequently found broken Belleville springs on machines equipped with them.. To get the required pull strength and travel can make for quite lengthy stacks (longer spindles). The stack needs supporting to keep the spindle balanced. Many release cylinders put the release pressure through the spindle bearings (not good), though it is not difficult to design an arrangement that doesn't.
If using air to release the tool, many machines require tandem cylinders to get sufficient thrust. Assembling the things can be a bit fraught, as the stack has to be pressurised in order to screw the clamping element into the release shaft.
 
Another variation uses ball bearings to clamp the pullstud instead of a collet - a sleeve with 4 holes drilled "not-quite-through" holds the balls captive in the spindle. An groove in the spindle allows the balls to move away from the pullstud when the sleeve is moved to release the tool & the pullstud is released. When the sleeve moves to clamp the tool, the balls move out when they contact the end of the groove & catch under the pullstud head. A Wadkin vertical machining centre where I did my apprenticeship had this arrangement - one operation on stainless ball valve bodies was a back counterbore & a tough casting (or operator on bonus with the feed override on 150% !) could pull the tool out of the spindle. And the ball bearings with it. . Apprentice maintence person (me) would have to lie under the spindle wearing goggles & attempt to replace the balls in the sleeve with a long screwdriver & a dollop of grease. I don't know if the sleeve was drilled through (which allowed the balls to escape) of it pulling the tool out had opened the holes out. A hydraulic clamp cylinder would not have allowed it to pull out in the first place !
 
If I were designing a compact system "from scratch" I would investigate internal clamping - as used on modern high speed machines (HSK, Sandvik Coromant Capto or Kennamental KM) like this :
 
http://www.berg-spanntechnik.de/wEnglish/produkte/werkzeug/hsk_auswahl.shtml
 
A much stiffer system, as the flange on the front of the tool is pulled in to contact with the spindle face as well as the taper . The industrial products detailed are tri-lobed designs (The Sandvik system requires a licence to incorporate it, not sure about KM, but I think HSK is "open source"). A low power system for home use & manufacture would probably work fine with a straight cone.
 
HTH
 
Nigel B.
Thread: Is 0.1 deg good enough..
19/12/2011 13:32:38
So does the accumulated wisdom here think that leveling to 0.1 deg is 'good enough'?
 
Not by a long way, if you want to do the job properly. A precision level with 0.05mm/Metre sensitivity or better - at my previous employment we had a 0.02mm/Metre block level as well as 0.05 box levels - & aim for 1/2 a division error or better. I was able to "borrow" overnight the 0.02 level to install my Myford & it levelled to within the width of a graduation line in both planes - near enough !. When checked again a couple of years afterwards there had been very little movement & only minor adjustments were required.
 
the absolute dead level is not necessary.
 
It is if you want to check alignment to British or other National Standards. The first check on all those I have worked with is to check absolute level in both planes & there is a (tight) tolerance specified. Some machines (slant bed lathes for example) require a levelling fixture to hold the level, due to lack of suitable features on the bed. One of the "challenges" of installing machines & demonstrating the alignments is that you are very limited in what you can tweak - due in part to the levels being "tied up". It was frequently necessary to push one check (say, levels)to one side of the tolerance band in order to get another check (say, squareness) to come in on the other side. Small adjustments & frequent re-checking of all the values being the order of the day.
 
Regards,
 
Nigel B.
Thread: 3 phase motor connections
16/12/2011 16:11:26
motor was started as ‘Star’. After the starting surge died down and the motor came upto speed; the ‘Memota’ type unit automatically switched the wiring into Delta. Star takes a lot of current and spins the motor up to speed changing it into Delta reduces the current flow and the motor then cruises doing its work.
 
I think you will find that it's the other way round - star connection takes less current. That is the whole reason for star-delta starting - to reduce the initial current draw. It also starts the motor with reduced torque, giving the device being started an easier time. It is not usual to star-delta start small motors - I can't recall seeing a motor under 7.5hp started in this way.
 
It is usual these days to use an electronic "soft start", as these give more control, include current limiting functions & the price is not usually much different to a star/delta starter + oveload.
 
Regards,
 
Nigel B.
14/12/2011 20:37:39
There will be four terminals
 
Definately only 3 on my motor - had to brave the cold to go out to the garage for something else & checked. 3 black wires to studs on a paxolin plate. That said, the rating plate unambiguously states 415v only, with no mention of 240v operation. I would guess that my machine is '60s built - blue/grey paint and old-style name plates - later machine probably had different motors.
 
Nigel B.
14/12/2011 19:06:02
I seem to recall that the 3 phase motor on my Boxford shaper was 415V star connection only. I swapped it out for a second hand single phase motor to get the machine operational quickly for least cost.
 
The rating plate could be a "generic" one - are there any current values stamped in the "Mesh" area of the plate ? Current at the lower voltage should be higher. If there is only one current value & un-stamped areas on the plate, I would suspect that the motor is single voltage star wound. Only 3 connections (or 3 wires from the stator) in the terminal box would confirm this.
 
You can get 240V input / 415V output inverters, though I don't know how happy they would be starting a shaper and they are not cheap You may have to go oversize with the inverter to handle the starting load.
 
You may be able to dig into the motor to retreive the star point & attach 3 more wires - though there is a risk that you will break a wire off & the motor would then require a rewind (or replacement). Been there, done that, payed for the rewind ! (on a different motor, though).
 
My single phase shaper is rather rough running, as single phase motors are not as smooth as 3 phase - the cabinet doors buzz quite annoyingly when the motor is running. Having recently "invested" in a Clarke static converter, I may put the 3 phase motor back on and trying the converter on it.
 
Regards,
 
Nigel B.
Thread: Fitting Power Feed to Chester Super Lux Mill
08/12/2011 20:51:11
Have a look here :
 
http://www.use-enco.com/Machinery/205-6404.pdf
 
for the Enco version manual, which appears to be largely the same as the Align unit fitted to my RF30 mill/drill .
 
HTH,
 
Nigel B.
Thread: MEW, would less be more?
07/12/2011 20:06:11
it doesn't really matter if you don't understand the attitude so lolng as you buy the mag.

Ah, but I don't any more. I think Issue 184 was my last, having subscribed since around Issue 8. Finally got unhappy enough with 13 shallow issues a year to ring up & cancel the DD.

if you are going to moan about magazine content send it to the Editor
 
Tried that - not going to change anything any time soon, I think. Hence my decision to drop out.

If everyone thought that, there would be no magazine. If you think it could be better, help make it so.
 
I reiterate - this is a commercial venture, not a club magazine. While the motorcycle magazine I subscribe to has submissions from readers, the content it is primary written by the magazine staff. This no longer appears to happen with MEW, probably due to the current Editor also being responsible for ME as well. Which brings us back to the original question posed at the head of this discussion....
 
I have, in the past, edited & layed out a national motorcycle club magazine (1200 or so members), so I can sympathise with DC1 & realise that you cannot please all of the readers all of the time. A club magazine is reliant mainly on submissions from members to fill it (and 64 pages in A5 format, bi-monthly take some filling - very few adverts !).
 
But when short of articles, or when the balance appeared a bit one-sided for the next issue, I sat down & wrote something. Or perused my photo collection for something a bit different. Or set out & took suitable pictures of my bikes or events - anything to fill the space with something relevant & varied. Only once, early on, did I make the mistake of "just putting in the stuff to hand, as supplied" to fill the space. Grapevine reports (rarely was anything mentioned directly) suggested (quite strongly !) that was not the way to go, hence the change of direction.
 
Yet comments about the content of articles in MEW seem usually to elicit the reply "that is how it was submitted". There doesn't seem to be any "Editing" ? Just assembling "the stuff to hand, as supplied" ?
 
I appear to be somewhat out of step with the general concensus about the frequency & content of MEW. I have voted with my feet, so to speak, and so will make no further comment on either topic.
 
Regards,
 
Nigel B.
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