Member postings for mgnbuk

A quick way for the UK to reduce consumption of unnecessary power would be turn off office lighting when the office stands empty

Depends on whether or not the lights can be switched off - I have a recollection that some office blocks were built without light switches, as it was deemed cheaper to run the lights all the time than install switches when the block was built.

Currently looking into having a DEFRA approved wood burning fire installed in place of a hopelessly inefficient coal-effect gas fire. At least I would have one room capable of being kept warm if the power went off - house has gas CH, but it still requires electric to run.

Worst case scenario would be to decamp to the motorhome on the drive during power outages, as the heating is gas with control electrics being from the 12v habitation battery that is recharged from a solar panel.

Nigel B.

My understanding of the history of the introduction of mass production is that Marc Brunel (Isambard's dad) built the first ever mass production facility at Plymouth Dockyard making pulley blocks.

I have a recollection that there was an long running series in ME during the period I subscribed about the machines & methods used to make the pulley blocks, which may have included modelling the machines.

Still got the magazines, so could get details of the issues that covered this if anyone was interested.

Nigel B.

I have not heard of heating bearings.

A widely used technique - SKF and others sell (ferociously expensive) induction heaters specifically for the purpose of heating inner races without using localised heat sources that could distort the race or interfere with the heat treatment. My previous employer used to hire one in from the bearing supplier to fit headstock bearings to large lathe spindles. The heaters we used had a temperature sensor that was attached to the race & the heater warmed it to a preset value. The other option was to use an oil bath, but that becomes awkward and messy (with attendant fire risk) with bearings of 2-3 foot bore.

The MZ manuals give dimensions for the inner race heating billets for the various bearings in their workshop manuals.

Another option (where heat isn't an option or appropriate) is deep cooling in liquid nitrogen. We used BOC Cryoservice (sp ? ) for that. Pop your shafts in liquid nitrogen for a minute or so & they would fall into the bearing !

I think more of "interference" fits rather than "press" fits - I don't particularly like pressing bearings if I can find another way (a bit of heat usually). The interference is to stop movment between the bearing and housing / shaft in service, so that the bearing carries to load & the housing / shaft don't get worn.

Nigel B.

You'll soon tell if the fit is too tight a fit. The bearing will tighten up on installation. If that happens, you can press it off again and reduce the shaft diameter.

Or use a bearing with more internal clearance.

On MZ motorcycle engines both inner & outer races of the bearings are an interference fit, requiring the crankcase to be heated to 120 C to fit the bearings, then the bearing inner race heating with a pre-heated plug to fit the crankshaft. The bearings need to be C4 clearance, as the effect of the interferences reduces the bearing internal clearance - using a "standard" clearance bearing gives noisy running & shortens bearing life..

From memory, the SKF bearing application manuals give indications of the degree of interference fit required for both housings & shafts for different applications - reciprocating loads or drivers required heavy interference on both IIRC to prevent the bearing from rotating in the housing or the shaft rotating in the bearing.

Nigel B.

I recently came across one of the pellet-type "fuel catalysts" while removing the petrol tank from my employer's VW Type 2 camper.

Wrapped around one of the filler cap retaining plate screws was a length of thin plastic covered gardening wire & pulling on the wire drew out the package of pellets from the tank - presumably whoever put it in in the first place wanted the option to be able to remove his expensive investment when the vehicle was sold ?

As the VW had the 1600cc engine, this is a 6 pellet unit. The stainless mesh covering is stained (the bottom of the tank was lightly rusted ) except for the bottom face which was in contact with the tank. The pellets are free to move in the mesh & are polished on their edges from contact - the flat top surfaces have the rusty coating, but the curved undersides are still bright.

No idea if the original installer found if the product worked or not. The van is a '79 & was owned from new by the same family. It came with a receipt for an exchange engine, which had been fitted at around 92K miles which, from what I have read, is pretty good for an air cooled VW ?

Nigel B.

Split systems come pre-gassed and essentially mount a unit indoors, place the outside unit, drill a hole for the hose and plug in plus a power supply

You also require a suitable vacuum pump to evacuate the system & remove moisture before releasing the gas.

37 C near York yesterday, but the wheezing, rattling floor standing air con unit in my "office" (half a Portacabin) at work kept the temeprature to a bearable 27C & the car aircon made the journey home comfortable.

I have a ceiling fan in the bedroom, so last night was also comfortable. It was 21 C at 6.30am this morning as I left for work.

Worst temps I have had to work in was in Dubai in July - 48 C with very high humidity. The factory was supposedly air conditioned, but the units were mounted along one wall & I was was working next to the opposite wall, sheilded by the lathe I was working on. I ended up fashioning a "Rambo" style bandana from rolled up paper towel to stop perspiration running into my eyes & religeously drank 2 cups of water from the chiller every hour. Still I was better off than the works maintenance fitter, who had to visit the Saudi subsidiary works - 55 C & no air con there. Then, after a 12 hour day, I returned to hotel room chilled to 16 C & had to request it be warmed up ! Ended up with chest problems after a fornight of that regime.

Nigel B.

But those foreign johnnies would struggle to work out the standard Whitworth system anyway, being born and raised on the entirely rational metric system!

At my previous employment we reworked a wartime built (WW2) German crankshaft grinder where all the threads were Whitworth. The machine came with all it's original documentation, with b & w photos stuck to type-written pages. From the number of throws on the mounted crankshaft in the pictures of the set-up machine + the size of the machine, I supect that these were U-boat diesel engine crankshafts. The machine most likely came to the Uk as reparations.

The gauge is for counting TPI not determining flank angle

I disagree - it is quite possible to determine the flank angle from thread gauges when held against the light. I have Unified, Whitworth & metric gauges at work for identifying threads, with the difference in "sight picture" on UN & WW threads of the same TPI being pretty obvious.

Nigel B.

Robin,

Even allowing fore the vagraries of display colour reproduction, the dark green sample paint you show touching up the edge of your cover is nothing like Reseda Green - the background colour does appear to be RAL6011.

Over more years than I care to recall, I have witnessed acres of Reseda Green on a great many machines - it was the default colour that my previous employer used on CNC machine tool rebuilds if the customer didn't have a specific requirement. Your Warco cover looks very like Reseda Green to me, as does the paint in the tin I linked to though, as with all paint, there will be variations between manufacturers & even between different batches from the same manufacturer. It isn't unusal to mix the contents of multiple new tins of paint before use on large jobs that require more than one tin to ensure that the colour is constant across the job.

Nigel B.

This Ebay seller has 250ml tins of enamal paint for £9.45 delivered & choice of colours includes Ral 6011 Reseda Green.

Nigel B.

Part 6 appears to be the precision sleeve that the quill runs in & the part that has broken off is the quill clamp.

Looks like it is a cast iron part that has done with flexing to clamp the quill - worn to the point that it had to be over-tightened to clamp adequately. Not much left to try to re-attach the broken bit, so probably requires a new part either purchasing or making (reverse engineer the part).

From memory the last manufacturer of these machines (who may well have been the original manufacturer in DDR times) was Saupe und Sohn, Georgstrasse 45, Limburg-Oberfrohna, Germany. Telephone 03722 6106 They don't appear to have a website & I don't know if they are still trading. The above details came from a German business listing website.

The "Prazi" title seems mainly to have been used to market these machines in America post German reunification - I don't recall anyone in the UK selling the former Hobbymat / Praezimat machines under the Prazi name. IIRC Pro Machine Tools did sell the former Hobbymat MD65 lathe as the Saupe SD300 at one time, but their website appears to be currently "down for maintenance" & they only seem to trade intermittently (based on earlier threads about them).

You don't say where you are based or what language your perfectly servicable translation was made from. Maybe worthwhile trying asking the question on a German model / hobby engineering forum ?

The above is probably not much help, but good luck with your search. If you do find a parts supplier for these machines, please come back & post the details.

Nigel B.

I cut a replacement chuck key square on a Boxford shaper before I got a milling machine, using a set square of the table against the first cut flat to set up for the next one. Repeated until all four flats completed. Shaft was sat on a parallel in the vice. Calculated the depth of cut from the O/D, measured progress on the first flat & zeroed the tool slide at the finished size & cut the remaining 3 flats to the same setting - finished square was a nice snug fit in the chuck jaw recesses.

Might not be absolutely dead-on square, but the chuck doesn't complain & I'm still using the key with no noticable difference in fit after several years.

Nigel B.

I have two defunct Clarke branded versions of this design of combined belt / disc sander under a bench - rescued from the skip at my last employment after they failed.

Both were used exclusively for steel & cast iron and both failed in the same way - damage to the insulation of the motor windings by steel swarf causing the windings to blow. The windings are not encapsulated or impregnated, so the swarf that gets carried past the windings by the cooling airflow embeds into the windings and eventually wears through the varnish. This leads to a loud POP and accompanying blue flash on start-up & results in a dead unit.

I have in in mind to mount both units "back to back" on a frame & replace the motor rotors with vee belt pulleys and drive them from a single totally enclosed motor mounted beneath them. So far "intend" is as far as the project has progressed !

I use a combined belt/ disc sander similar to this Ebay unit , which has the advantage of having a separate sealed motor. It came from Netto (remember them ? ) many years ago and, apart from a number of loose connections, has worked well. IIRC I paid £30 for it at the time. It could do with a bit more oomph (375 Chinese watts IIRC ) but that does tend to stop me from overloading it & both belt and disc wear rates are low even if the job takes a bit longer.

Nigel B.

Bruce Engineering do a couple of external hone kits (now sold by Polly Engineering) of a single stone + vee block design - current catalogue shows the 1" capacity kit at £20.50 & the 2" at £30.50. Kits include castings, bar stock & stones, but you need to look in the downloadable .pdf catalogue to see them as the Polly website isn't great for descriptions or pictures.

Similar function devices appear to be available from Sunnen.

Nigel B.

Graphite bushes, run dry

Nigel B.

Due to my stupid comparison the engine side of the discussion has really taken over and that was not really my concern but thanks for all the contributions.

Not so much a stupid comparison, but trying to compare an example from one industry ( high volume, mass market, close tolerance products with a relatively low selling price) with another (low volume, niche market, close tolerance products with a relatively high selling price) - the needs of (or methods employed in) one industry do not necessarily transfer easily to another.

IIRC at the time I was at Boxfords (1980-81), they had a production capacity of around 2500 lathes a year - probably not a lot compared to Chinese mini-lathe makers today, but not inconsiderable for a UK maker at the time. They had a mix of manual & CNC machines to produce the parts & all the machines were hand fitted on an assembly line. There were bench fitters who put sub-assemblies together (headstocks, tailstocks, aprons etc.) and others who brought the sub assemblies together to get the required accuracy in the finished product. There were time impositions on the various steps - again IIRC , the fitter who fitted the tailstock to the bed & aligned it with the headstock (scraping the base of a previously assembled tailstock assembly to get alignment & centre height correct) was allowed 1/2 an hour. If tolerance stack-up meant that the fitter couldn't get it sorted in 1/2 an hour, that tailstock assembly went in the scrap skip ! I particularly remember that bit, as I "rescued" such a tailstock from the scrap skip and (over a lot longer than half an hour ! ) fitted it the the tailstock-less "bitsa" lathe that lived in the maintenance shop. That machine had been built up from parts rescued from the skip - starting with a bed that had a blow-hole at the tailstock end of the shears.

From what I recall of Myfords from visits during their open days, they operated along similar lines to Boxfords, (though the facility was obviously older) so not unreasonable to think that they would have built (i.e hand fitted) their machines in a similar way. Just the way it was, given the quantities produced

Did your bearings require "fitting" ? If you checked that your spindle didn't rattle or bind and the alignment with the bed was OK to meet your requirements, then maybe no need to break out the marking blue and scraper.

Trouble is as an amateur hobbyist with no more than CSE metalwork for experience and no access to real world help I watch lots of youtube and read forums if I get stuck on something. The alternative is to give up.

Another alternative is specialist publications, many of which were written when lathes like the ML7 were current but whose content is as relevant today as when they were written. Some of these are available as .pdfs online.

There will always be differences of opinion in forums & opinions on YouTube "experts" can depend upon the experience or background of the viewer - such is life.

Never give up !

Nigel B.

As an example I have a Kawasaki engine that runs at 10,000 RPM all day long, the bearing sizes are available to buy and fit and forget.

But if you look at the factory rebuild manual, it will tell you how to select the correct size bearing shells from a table - look up the crank & housing dimensions (often coded on the parts with coloured dots or simliar) and it will give you the correct bearing to use to get the desired clearance. Mass produced engine components are graded during production & assembly from the graded parts to get the required running clearances is easily assured.

Not so with a one-off or low volume application, hence the need to "check and adjust" by a suitably trained fitter. A true "fitter" is not just an assembly monkey - they make parts fit together as the designer intended..

Nigel B.

ISTR my old BMW "Airhead" has bronze guides and those things run forever without problems.

I must have been unlucky then, as both the "post 81" R100s I have owned wore the valve guides out by 50,000 miles.

I moved the first one on without fixing it, but fitted supposedly "superior" guides from a BMW specialist supplier to the second - which wore out in under 10K ! Apparently most users who fitted these guides didn't actually use the bikes much afterwards - so that was OK then ! Second fix was with OE BMW guides, which were fine for the next 5K or so that I did before moving that one on. The OE replacements were shorter than the originals fitted by BMW when the bike was built - apparently changed by the factory as a fix for the valve head seperation these models have a bit of a reputation for (stems friction welded to the heads). Heads heated to 240C to fit the replacement guides, using a s/h oven bought off Ebay for a fiver which was recycled afterwards.

I would look to fix the Guzzi properly with new oversized guide, fitted by someone with a proven track record. Choose your specialist carefully, though - one I made the mistake of using to change the guides & valve seats on T'Wife's R65LS was not as good as he thought he was. He fitted one of the valve seats with too tight an interference & it broke up, with the broken bits dropping into the cylinder. Even though the break-up occurred during a cold start (and the engine didn't fire, as it locked up) that scrapped the cylinder, piston & head . I was (eventually) able to source used parts, but I doubt it would be easy to do so for a pre-war Guzzi. I would not take any risks with such a bike.

Nigel B.

a three year old Boxford HA van

A slip of the keyboard there Nick ?

Nigel B.

I have a small bench top blast cabinet & a 2hp 50 litre compressor. The compressor is not able to operate the blaster continuously - it cannot supply enough air. What I do is let the receiver fill, then use the blaster for about a minute / minute and a half then stop & let the receiver refill. For bigger jobs I have taken the cabinet to work & used the 7.5Kw rotary compressor, which has no problems keeping up with air demand.

Another vote for not using sand if you want a longer life - my grandfather died of silicosis contracted while working in sandstone quarries & I would not like to go that way.

One of the bigger issues I have with my cabinet is the media (glass beads in my case) getting damp, as a standard water trap isn't enough to dry the air. I used a hot air gun blown through the media when it stopped flowing towards the pick-up & through the gun. Dust extraction is also an issue - difficult to do the job when you can't see it ! A small cylinder vac at home isn't really enough, but is better than nothing. Hooking the outlet up to one of the industrial extractors at work is noticably better.

Really depends on what you want to blast. The occasional small bracket / casting isn't too much work & it does a reasonable job. For bigger projects / lots of parts / larger parts I would sub the job out to a professional. I have done an aircooled BMW motorcycle engine cylinders / heads / outer covers in a small cabinet & would not choose to repeat the experience. Likewise did the frame for another bike with "disposable" grit using a dip-tube blast gun outdoors - it did the job, but really not much fun & very messy & the media wasn't cheap. For the next frame I sent it out and had it blasted & powder coated.

Nigel B.

Don't know how it can sense this

As well as the ABS sensor wheel speed arrangement that JH described above, there are also battery operated pressure sensors built in to the fill valves. These look the same as normal unsensed fill valves from the outside. The batteries on these sensors are non-replaceable, so when they eventually die a complete replacement sensor must be fitted and "coded in" to the car system.

On my last car (which had a sensor based system for TP monitoring) I had a spare set of wheels with winter tyres fitted that didn't have the sensors - replacement sensors are not cheap & must be "coded in" when changed, so I didn't bother. When I swapped over to these wheels, it took about 4 miles for the pressure warning light to come on, which stayed on unitl about 4 miles after I refitted the sensored wheels. No idea about how long the batteries last - that car was over 6 years old when I changed it, though about a year of that was with the winter tyres fitted. Given the 4 mile lag between loosing (or regaining) the sensors, I guess that the sensors only have to respond to an occasional request from the car systems for their status & that the normal battery drain is very low..

My wife's current car displays the actual pressures for each wheel on the car display, so easy to see which one is low. This system appears to trigger at a 3 PSI difference from the setting on the door pillar & activated the first time when the ambient temperature dropped below freezing.

Nigel B.

(edit for spelling)

Edited By mgnbuk on 13/05/2022 11:53:54

Edited By mgnbuk on 13/05/2022 11:54:10