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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: Slideways oil
20/10/2019 15:13:24

Of course where I have sliding surfaces designed to be 'total-loss' - for instance the Shapers ram slideways - I'll continue to use a thin oil (SAE 30) there...

Why ? Most machine tools have a total loss slideway oiling system & most recommend using slideway oil. I have come across a few that bled hydraulic oil to the slideways from a continuously operating hydraulic system, but most industrial machines recommend using a 68 viscosity slidway oil - heavier machines can use 150 or 220 grades to support greater loads, though. Wierdest one I came across was for Keller copy mills, which wouldn't work properly with anything other than a specific manufacturer's Sperm whale oil based product. Butler used to recommend another specific oil (Germ Dynobear 68 IIRC) for their travelling column milling machines as it substantially reduced stiction compared to "generic" oils in that application.

FWIW I use a 46 viscosity slideway oil on my Super 7, Boxford shaper & FB2 clone milling machine (Millers Oils Millway 3 IIRC) - no point in using a heavy oil on lightly loaded slideways.

While I would agree that any oil is better than no oil at all, if a product is available at a reasonable cost that is optimised for a specific area of operation, why not use it ?

Nigel B

Thread: Turning between centres on Super 7
01/10/2019 14:25:23

The driving teeth are the sprung parts.

Not on Rohm face drivers - see page 39 on Rohm face drivers

for a cross sectional diagram which shows the spring loaded centre. The centre has to move to allow the part to contact the drive dogs under tailstock pressure.

The Rohm driving disc can "wobble" to take up out-of-square bar ends, which makes for rather pricey items at larger sizes - I have designed a simpler, lighter duty version for turning graphite blanks at work with fixed driving dogs, where an out-of-square end is taken care of by the initially contacting dogs slipping & digging further in to the blank under hydraulic tailstock pressure under cutting conditions. When all 6 dogs are engaged, the blank doesn't slip any further and, as the initial heavy roughing cuts just produce a parallel cylinder, the axial displacement of the blank caused by the dogs digging in under load is of no consequence. The sliding centre is a parallel Morse taper 1 sleeve, with a die spring behind it - the spring rate was determined by trial & error (die springs are suprisingly cheap), with a Morse taper 1 centre providing an easily replaceable "point" if required (which it hasn't been for over 6 years that the home made unit has been in service).

Nigel B

Thread: DraftSight no longer free
25/09/2019 07:39:04

I had a look at the Drafsight website yesterday & see that the free version is no longer available - the "free" option now is for a 30 day trial, then an ongoing $99 a year. As I said initially, the "pop-up" that appeared for me which prompted this thread stated that all "free" versions would cease to function at the end of the year - nothing on the website suggests otherwise.

Nigel B

Thread: Heidenhain scale repair
01/09/2019 13:17:41

John,

I have not had to use a Heidenhain agent, though I don't doubt what you say from recent experience - I just bought heads direct from Heidenhain to exchange myself. I have dealt with Heidenhain for a long time (since 1983) through my previous employment (a CNC retrofit company) & have just continued to do so where I am currently (maintenance for a machine shop). The last scale I bought was several years ago to replace one that had been damaged on a Cincinnati machining centre - the machine head had dropped during transport & punched the read head through the bottom of the scale, damaging the glass in the process - about £1500 + Vat for an 1100-ish long TTL output scale with distance coded reference marks IIRC.

Dave,

Sounds like your scale itself is OK. It is a long time since I had the conversation, but I have a recollection that the reason that the lamp was not user replaceable was that precise focussing was required. Being a good Yorkshireman, I had enquired why a £300 (at the time ! ) replacement head was required because of a failed £1 lamp. As the 11 micro amp scale signal is the un-amplified output from the photo cells, the lamp position had to be set precisely on a test rig to get the correct signal output - it would have cost more to send a head back to have the lamp changed & reset than a new replacement head mass produced at the factory cost. From an industrial point of view, I can get a machine up & running more cost effectively by fitting a new head if one fails - OK £500 or so isn't cheap, but it doesn't take long to cost a lot more than that if a machine is out of production.

I don't know enough about the components used in the heads, but could it be that your Led is too bright, too diffuse, or the wrong colour temperature ? My recollection of the originals with the lamp is that they were a very dim yellowish light - as you would expect from an incandescent lamp running at less than half it's rated voltage. Could you mask the Led to replicate the illuminated area produced by your good head with the lamp ? And / or dim the Led with a series resistor ?

The last time I had a DRO related failure (the counter failed on an Anilam readout on a Harrison lathe) I didn't bother getting a price to have the counter repaired or replaced, just bought a complete system from Machine DRO at around £400 including Vat and delivery. A bit more fitting time to swap both scales & mount the new counter, but the new installation was warranted & has proven reliable.

Nigel B

31/08/2019 13:53:19

Heidenhain used to use a 12v lamp running on 5v in read heads and encoders - they were just a dim glow, but lasted thousands of hours (20,000 hours was quoted IIRC). When a lamp failed, the read head or encoder was replaced. IIRC the lamp positon was adjusted at the factory to position it correctly behing the read head grating to optimise the signal output. As far as I can remember it was only the very high line count rotary encoders intended for direct mounting on rotary tables that had the lamp changed when they failed, but it required the encoder to be sent back to Heidenhain for repair - as these encoders cost many thousands of pounds, a repair of several hundred was cost effective. Scales were able to be repaired relatively cheaply by the end user by replacing the read head.

Have you tried cleaning the the scale grating if you only have a localised problem ? I have done this on contaminated scales that read intermittently by removing the head assembly & the sealing lips, then carefully cleaning the grating with tissues and IPA. Go easy. don't apply a lot of pressure or use sharp tools and beware the sharp edges of the glass ! With the sealing lips out you can examine the glass grating for contamination & obvious damage - the grating should look like a contiuous grey band down the length of the glass strip. Any scratches or discontinuities here would scrap the scale.

Your scale must be old to have a lamp, as Heidenhain went to Leds many years ago - maybe IR Leds, as I don't recall seeing the dim glow when looking down the length of a scale with an end cap removed on later scales. Be aware that Heidenhain counters were usually sine wave input, not square wave. Early units were 11 micro amp output, current items are 1v peak-to-peak . Various signal converters are available - I have used 5v TTL square wave to 1v peak-to-peak converters on retrofits.

Given Heidenhain repair & new part prices, it would probably be cheaper to replace the entire setup with a new Chinese counter & scales and sell on the working parts of the Heidenhain setup to recoup some of the cost. Not knocking Heidenhain in any way here - they are a very professional producer of high quality industrial equipment and their service is second to non, but their pricing reflects that and isn't exactly "home workshop friendly".

You could give them a ring on 01444 247711 and ask the Service Department for advice - they don't bite.

Nigel B

Thread: Exhaust Gasket
25/07/2019 13:26:52

Standard "gasket" on two stroke trials bikes I have had was a smear of clear silicone sealant on the joints at assembly.

Nigel B

Thread: Colchester Lathe Factory
31/05/2019 14:11:41

That doesn't look a whole lot different than Boxfords at Boxtrees Mill in the early '80s, though Boxford didn't have their own foundy & all the castings were "weathered" outside for months before clean-up in a similar shot blaster. The filler used then was two part polyester body filler, still rubbed down by hand.

Today's Student and M300 are badge engineered clones of each other. And currently built in Taiwan. They have also variously been built in recent years in Russia, Czech Republic & China. The TS Harrison plant in Heckmondwike, which is where Colchester Lathes production was re-located after the site shown was sold (IIRC to become a Tesco supermarket) was closed last year. The last products made there were the Harrison Alpha "manual plus" lathes & Colchester Tornado slant bed CNCs - it is probably at least 15 years since the last manual lathe was made there. My brother in law served his time at TS Harrison & was charge hand on the small turned parts & gear cutting section - he left when production of the manual machines ceased, as the variety of parts for the CNC machines was very small. Even then the M250 was made in Russia & I recall around the same time the owner of a machine shop I used in my last employment being very unhappy to find that the "top of the range" Colchester he bought new was actually a re-badged Czech machine.

The graphite product used to face the sand mould was probably DAG colloidal graphite suspension, which is supended in alchohol. It is still available & we have a 205 litre drum at work for use in vacuum furnace applications.

The paint used to seal gearbox internals was also spirit based. When I worked at Broadbent Machine Tools as an electrician wiring heavy duty lathes, we used to use it to paint out the insides of the electrical sections of castings (the fitters did the gearbox castings & didn't touch "electrical" bits !). It was quite a "claggy" paint that dried very fast - clean-up & thinning was done with methylated spirit. When dried oil didn't soften it & one of it's purposes was to bind any sand remaining in the casting to prevent it getting in to the oil and causing wear.

Nigel B

Thread: An old Shaper found in Phuket Town
22/05/2019 18:58:17

I worked for the Cincinnati Milacron Electronic controls div which had a UK centre in Bedford

The Technical director at my previous employer worked there. I guess he would have been there in the late 70's - do you recall Dave Crewe at all ?

Nigel B

Thread: What Did You Do Today 2019
21/05/2019 20:35:24

The lead pellet weighs about 1.2 grams and would have been travelling at about 220mph on impact, about 8J of energy.

I don't think that your energy calculation is right, Dave.

Working in the more conventional units for airguns in the UK, 1.2 grammes pellet weight equates to 18.52 grains. This seems high for a .22 wadcutter. The pellet you show looks like a H & N Excite (12.82 grains) or RWS Hobby (11.9 grains) ? 220mph equates to 323 feet per second, which is round about what my recently departed Webley Tempest put .22 Hobbies over the chrono at, so seems about right..

However, 11.9 grains at 323fps works out at 2.76 ft pounds energy (3.74 Joules) - quite a bit short of 8 Joules. Even if your pellets are 18.52 grains, that is still only 4.29 ft pounds (5.82 Joules) - closer, but still no cigar. Still, you do seem to be comfortably on the right side of the law for the UK air pistol power limit of 6 ft pounds (approx. 8.13 Joules).

I don't think you should be too suprised that 3.5mm of polycarbonate stopped a pellet - I seem to recall seeing a demonstration on TV some years ago of a 1.5mm polycarbonate visor designed to clip on to a standard UK policemans helmet stopping a full power air pistol pellet at point blank range.

Nigel B (now enjoying a Weihrauch HW40 in .177)

Thread: An old Shaper found in Phuket Town
21/05/2019 20:07:41

Quite a small planer & quite basic - most (probably more recent than this) that I came across had at least two toolboxes on the crossrail and one one each vertical way on the columns. This one doesn't look like it was intended to have the vertical running toolboxes, as the crossrail ways (also used for the vertical toolboxes) don't go below the top of the table. I have seen one operating with all 4 tools at once roughing out the top & both sides lathe bed casting - quite a time saver if the job allowed it.

At my last employment we converted a Butler planer (8' x 8' x 40' IIRC - rescued from "outside storage" at a paper machinery manufacturer) to CNC operation. While primarily a milling machine (a new milling head replaced one of the toolboxes), the customer wanted to retain the planing operation. The customer made points & crossings for railways & tramways and thought that they could plane the wheel flange clearance groove in large radius crossing castings. It did work after a fashion, but the problem was tool clearance in the groove - the tool really needed an additional rotation axis to keep the tool perpendicular to the rail face as it went round the curve & as it didn't have one the tool had to be ground back so much to give clearance that it was too weak.. We used a 37Kw AC spindle motor in servo mode though a ZF low backlash reduction gearbox to drive the table, with two sets of parameters for planing or milling operation.

Sadly now a largely dissappeared breed - not "cost effective" enough for a modern production environment that seemingly doesn't value their strengths & capabilities. A situation that I have, unhappily, helped along at my current employment when the owner decided to scrap a very tidy, one previous owner Swift Summerskill planer rather than convert it to a milling machine. There have been a number of machines I have been glad to see the scrap man take away in bits, but that wasn't one of them & I still feel bad about it.

Nigel B

Thread: DC Treadmill Motor
16/05/2019 19:39:36

I have tested it with a 12v DC model railway controller. It goes forward and backwards OK but without any great power.

Fixed field DC motors are constant torque devices, so power reduces as rpm reduces. Rpm is dependant on the voltage applied & the torque comes from the current - so if the motor is 1.75hp @ 4400 rpm from its rated current at 180VDC as suggested, then at 12V you would get around 300rpm and around 0.12hp assuming you supplied the rated current (7.25ish amps).

1.3Kw (as suggested above) at 4400 rpm is around 2.8Nm torque - should be enough to move the head on an FB2, but you would be running the motor at a very low voltage to get the motor to run slowly enough (unless you require very rapid retractions !) . It doesn't strike me as being the ideal motor for the job - FWIW I have bought a 3Nm stepper motor to do the same job on my FB2 clone, but I particularly want to use mine to get a constant downwards cutting feedrate (I have it in mind to try boring motorcycle cylinders, so need to be able to feed at a constant rate for around 160mm) - powered elevation will be a bonus . I have all the bits, just need the "round tuit" now to get it mounted on the machine !

Nigel B

16/05/2019 10:27:46

At this power rating the motor probably has a would field

Motor part no includes "MOTOR P.M.D.C. POWER 1.75HP "

PMDC = Permanent magnet DC ? The small wound field DC motors I have come across have had the field as a separate enity, not connected to the armature. Frame size looks rather compact to have a wound field as well + no apparent cooling slots - wound fields tend to run warm & require ventilating.

Nigel B

Thread: Parkson M1250 Beast
14/05/2019 16:24:34

Indramat 3TRM2 drive amplifiers (3 axis - 2 pulse thyristor drive) are pretty bullet-proof. Previous employer used them as standard (used to buy the 20 off at a time) & I can't recall having to change one out. Can't see if the DC servo motors are Indramat or "other" - we used to use SEM but both wer reliable. Likewise Heidenhain TNC controls. All are now obsolete, so getting repairs done if they are faulty could be either expensive or not possible.

If you have a 3 phase supply, hook it up & give it a try. The 3TRM2 is not polarity sensitive & is actually single phase (IIRC 160V-170V AC input from a transformer), though the transformer Parkson used may not have a tapping to run off 240V.

Replacing with modern drives of similar capability will not be cheap.

Nigel B

Thread: Myford ML7 - Size of Mandrel Through Drilling?
11/05/2019 15:11:51

How can you miss it Nigel? It's on the front shear vertical face

Not on mine, Brian.

Its at the back of the rear shear at the tailstock end of the bed and my lathe is close to a wall, so I can't get my head in the space far enough away to be able to focus on it (one of the "pleasures" of getting old ! ) . However, use of the camera in my phone has allowed me to see the number remotely , which is SK78311.

Nigel B

11/05/2019 13:11:43

0.630" from a quick digital caliper measurement on my mid-60s Super 7 (can't easily get to see the serial number).

Nigel B

Thread: Honing motor cycle small ends
10/05/2019 10:00:39

As Mr Harley said to Mr Davidson, a little extra clearance never got in the way.

I doubt that Mr Honda ever said that !

Nigel B

Thread: Bore micrometer
10/05/2019 09:55:06

Are these not "comparators", rather than "micrometers" ?

To use them, a ring gauge of known size is used to set the zero on the dial gauge on the comparator, then the deviations from the setting gauge in the bore to be checked are read off the dial gauge. The comparator in itself is not an "absolute" device.

Nigel B

Thread: A visit to Manchester Sci and Eng Museum
29/04/2019 10:35:46

Not true, according to Wikipedia 160,000 built in the UK and 55,000 Packard versions in the USA and production in the USA did not start until late 1941.

**LINK**

Ford built Merlins in quantity at Trafford Park.

Nigel B

Thread: ZAY7045FG/1
23/04/2019 13:43:39

This machine looks similar to the Grizzly G0761, for which a manual & parts list can be downloaded here

**LINK**

To remove the quill it looks (from the parts list exploded diagram) that you remove the feed pinion assembly, return spring & depth stop and the quill should drop out from the bottom of the head. It may also be possible to access the preload locknut from above with the quill in place by removing the gearbox top cover.

The quill design seems similar to my RF30 mill/drill.

HTH

Nigel B

Thread: Lathe bed regrind
23/04/2019 08:16:46

R Skinner Slideway grinding are in Halifax

Not for a long time. Bob Skinner sold out to Bob Pickles IIRC over 10 years ago - the Shay Lane address is where Bob Pickles operated from after Bob Skinner's machines were relocated (Bob Skinner chose to sell up & retire when he had to move from his rented premises). As far as I have been able to ascertain, I don't think Bob Pickles is trading any more either.

Bob Skinner was the primary regrinder we used at my previous employment (CNC machine tool rebuild & retrofit) & I had the pleasure of working with him to solve some "interesting" problems that came up from time to time. He set the highest standards & was extremely tenacious in getting to the bottom of problems. He delighted in getting me to work out solutions & set-ups when there were problems, gently prompting or offering advice, but making me work things out - it was always a pleasure to work with him. IIRC he had been the planing shop foreman at Butler Machine Tools in Halifax before starting up on his own. At the time he was served notice to leave the premises (the landlord wanted to do other things with the building) he was not far short of retirement age & had had health problems, hence selling the business.

I can only recall using Bob Pickles once after he took over from Bob Skinner & visited his premises on Shay Lane to discuss our requirements. IIRC he only took one or two of Bob Skinner's 3 planers & was a sole trader. He offered additional services like applying & pre-machining anti-friction coatings (Turcite etc.) to minimise fitting time. The job he did at that time was also to a high standard. I can't find any current information about this business from local sources.

Nigel B

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