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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: Sandblaster
19/05/2022 08:13:25

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.

Thread: Tyres
13/05/2022 11:52:34

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

Thread: Milling Table Flatness - What is acceptable
12/05/2022 11:10:38

To be pedantic - you are not checking table flatness here, rather the parallism of the working surface of the table to the slideways. The table surface may well be flat (you would require a precision surface plate or straight edge to find that out ), but it isn't parallel to the slideways according to your caliper measurements.

While taken measurements are not from the working surfaces, chances are that the non working face that has been measured from was machined at the same time as the working surfaces - rather confirmed by the measurements show by the DTI. Re-measuring from the working surfaces would confirm this.

As has been said already, the cure for this issue is to regrind the table top with the table set on parallels from the working surfaces - not difficult if you have a suitable surface grinder available. Must have taken a bit of effort on the part of the manufacturer to make it that far out !

The issues related to movements / distortions caused by the excessive overhang of the table from an underslide & base arrangement that really isn't wide enough for the table travel is another can of worms !

Nigel B.

Thread: Boxford AUD/BUD single phase conversion
10/05/2022 20:00:50

Not sure what to replace the start/stop switch with though? I assume this will need to be wired on the output side of the VFD unit and therefore compatible with the output voltage i.e. 3ph 230V?

Read the VFD documentation.

Usually there is an NVR on-off relay / contactor to supply power to the VFD & low voltage pushbuttons connected to the control inputs side of the VFD for motor direction and run / stop operation. Switching the VFD output is not usually recommended & could damge / destroy the VFD if the contacts are opened while the unit is under load.

That you are asking these questions suggests that you are not familiar with these devices - mains voltages can easily kill you so, if in any doubt, consult someone who is familar with their safe installation & operation. Don't guess or try "winging it" !

Nigel B.

Thread: Rail wear
10/05/2022 15:43:10

I think it's a fake.

Maybe not - could be a close-up from this :


Suggestions from postings accompanying this photo are that it was from a double (or more) headed train where one of the remote operated locomotives didn't respond to the train braking (or something similar - not a train buff ! ) & continued driving. Seems like it may have been in North America, where some locomotives have 6 wheel bogies. Other posts from railway employees suggested it was not an unusual occurance & was easily repaired by cutting out the damaged section of rail & thermite welding in a new bit.

Nigel B.

Thread: New To CAD? No, but....
10/05/2022 11:03:10

What's the best freeware to draw 2D images, suitable for doing dimensioned drawings to go with MEW magazine articles?

With the demise of free-to-use Draftsight I moved to NanoCad, after trying QCad & a QCad derivative whose name escapes me at the moment LibreCad (thanks Dave ! ). NanoCad appeared to handle my legacy Draftsight drawings better than QCad & I could configure the interface almost identically to my Draftsight arrangement (which I configured almost identically to AutoCad LT), so there was little new learning required on my part. Where there are differences, the Help files have been adequate. The only feature I miss is NanoCad is incapable of drawing a line tangential to 2 circles.

NanoCad is a Russian product, though, which - given the current situation - may be a choice you don't wish to make.

Nigel B.

Edited By mgnbuk on 10/05/2022 11:05:06

Thread: Time to Say Goodbye
09/05/2022 15:57:44

Ant ideas for a replacement home engineering subscription?

Readly ?

ME, MEW, EiM & the German magazine Maschinen im Modelbau all on there now (along with 6000+ other titles) for £9.99 a month. The latest issue of ME was posted late last week. Not much in the way of back issues for ME (current + 2 previous) & non for MEW yet (just latest issue), but EiM & MiM have both been on Readly for a while & there can be couple of years worth of older issues.

I use Readly on an old Tesco Hudl. Copies can be saved to the device memory for reading offline, but I am unaware of any print options. You can try Readly FOC for 2 months before the monthly charge kicks in & the subscription can be accessed by up to 6 (IIRC) e-mail addresses linked to the main account.

Not an option if you want to build up a paper archive, but if you read & pass on (or recycle) paper copies & have a suitable device it might be worth a look.

Nigel B.

03/05/2022 20:40:48

I believe the size of the particle is the deciding factor when conducting a test for ingress of dust, it matters not whether the particle is conductive or not.

From an "expensive bang" POV it matters quite a lot !

I work for a graphite machining company & the talcum powder fine stuff defies all attempts to totally keep it out of enclosures despite my best efforts - and that is IP66 industrial enclosures.

Nigel B.

Thread: Workshop warming
28/04/2022 13:04:33

I bought a vehicle diesel night heater kit ( like this ) & fabricated an angle iron frame to hold it and a 12V PSU for heating my garage/workshop.

Making the frame was a bit of a pain & if I were to do the job again I would start with an "integrated" version like this Diesel heater and power it using a 12v PSU (the heaters take around 10A to start up & around 2A when running at temperature). The integrated versions have a built-in 5 litre tank, but mine sips from a 25 litre oil drum.

Be aware that the exhaust must be routed outside the building & that the exhaust pipe gets very hot !

They will run on either red or white diesel, parafin or heating oil & a 5Kw version uses about half a litre an hour running flat out. Mine is a bit noisier than an electric fan heater inside the garage (but not objectionably so) & the exhaust (with supplied silencer fitted) is a low purr outside the building . Unlike an electric fan heater it does actually warm the space !

Nigel B.

Thread: New to Model Engineer
27/04/2022 16:17:53

Hi Kim,

Re : a lot boxford lathes came with metric dials as has mine its just the lead screw that's imperial.

That would probably have been a machine in an educational environment that was originally built & supplied as all Imperial. To reduce the costs to educational establishments when we went Metric, Boxford did a kit of metric cross & topslide screws, nuts & dials but just supplied a conversion gear for the Imperial leadscrew rather than a new screw, half-nuts & additional changewheels (or gearbox). IIRC it was a 100/127 gear - I had one for my CUD, but both lathe & gear are long gone now.

Boxford did supply all Metric machines unlike Myfords with the "7s", whose "metric" machines retained Imperial leadscrews AFAIK.

Nigel B.

Thread: Size of a Boxford metric Lead Screw
27/04/2022 14:40:02

Hi Kim,

If are correct, Denford sold the Boxford side to Harrisons in 1952 & designed their replacement machines after the split. If your machine is early '60s, that would put it as being made after the two companies split up ?

The descriptions of the Denford machines produced after they moved to Brighouse suggest that their design was different to the Boxford product to address perceived shortcomings. The pictures of the various Viceroy models on the site look quite different to the Boxfords & I would be very suprised if Viceroy parts would drop straight in to a Boxford.

Boxford used a Jowett thread whirler to manufacture some (if not all) of their leadscrews - a rather noisy thing, it was at the end of the workshop near the loading bay door ( I did the last year of my apprenticeship at Boxfords Sept '80 - Sept '81).

Nigel B.

27/04/2022 13:10:04

as denford made both machines

Maybe at one time, but they were two different companies with two different manufacturing sites for a very long time. I would be wary of assuming that the drawings for one manufacturer were interchangeable with products from the other.

Nigel B.

Thread: Alternative Ways of Retaining Shafts
26/04/2022 15:14:06

Starlock washers might do what you want, Dave.

Nigel B.

Thread: Myford induction hardened beds
25/04/2022 08:51:19

Does anyone know which parts Myford made themselves from scratch?

Can't say definitively, as I only visited their works a few times on the open days & when passing to get spares plus I own '60s built version, but probably more of the metal bits than you might of thought.

Small screws & nuts (like gib screws & locknuts & the special dome headed screws for the switch bracket as examples) on my lathe are different in design & rather better made than some"commercial" stuff + are chemically blacked rather than left bright. On one open day visit, a CNC lathe had a stillage full of leadscrew handle bodies (later solid type) made from bar stock next to it & in the gear cutting department one machine was set up making the keyed changewheel sleeves. I would not be suprised to find that they made (or machined from bought -in castings) most items in house.

Some years ago I "found" a British Casting Research Institute (or similar UK trade body) pamphlet from the '50s in a Hay on Wye bookshop that featured the ML7/Super 7 bed casting as an example of state-of-the-art mass production casting technology of the time, plus the use of die cast parts for brackets, covers etc. suggests that Myford were using the best available technology when the ML/Super 7s came out to maximise production at lowest unit cost. I would also expect that, coming out of a period of war production, that they were probably "self sufficient" with regard to what may now be regarded as "bought in" small parts to better guarantee production during uncertain times - continuing to make such small parts in-house would give better control of costs as well as supply post war ?

WRT to bed paint colours, my un-hardened mid-60s built Super 7 has the gap between the shears painted the same cream that the cover logos are highlighted with.

Nigel B.

Thread: Model Engineer now on Readly
22/04/2022 09:41:56

Looking at the latest publications on Readly this morning, I noticed that Model Engineer has now appeared - Issue 4689, with (currently) only Issue 4688 in the "back issues" section.

As Mortons motorcycle publications were already on Readly, I hoped that ME & MEW would follow suit - it hasn't taken Mortons long to get their recent acquisitions out to a wider audience.

When MEW appears, that will make Model Engineer, Model Engineers Workshop, Engineering in Miniature & Maschinen im Modelbau all available on one subscription service. American pubishers don't seem too keen to embrace the subscription services, so Home Shop Machinsit & Machinists Workshop probably won't be along any time soon.

Nigel B.

Thread: Magnetic DRO-S7
21/04/2022 09:18:07

Given that the lightweight section the tape is mounted to is only double-sided tape attached to (presumably) unmachined surfaces, how accurately aligned with the slideway is it ?

I fitted one of M-DRO's spar mounted magnetic scales to a linisher at work. The spar they supplied is much heavier section than yours appears to be & I spent quite a bit of time aligning it (front & side) with the machine travel to within 0.02 over the full travel - same as I align glass scales. Read head gap was set with a piece of paper IIRC. Readout is accurate & repeatable and has poved far more reliable than the capacitive arrangement it replaced.

Nigel B.

Thread: Wanted "Minnie" book
12/04/2022 20:25:27

Found it - eventually ! My "almost zoned by interest" bookcase arrangement failed on this occasion - probably because I read it again a couple of years ago & didn't put it back in the right place.

1971 MAP Publication hardback, looks like it might be a first edition in generally good condition. All pages appear to be present, no corners turned, haven't seen any "notes" made, but there is a bit of wear to the top edge of the dust jacket. Doesn't smell particularly "old book" or of stale smoke & the binding is tight.

Send me a PM if your are interested - as I said, I am not likely to build a Minnie & I'm sure we could work something out if this is the printing you are looking for.

Nigel B.

12/04/2022 14:31:59

I think I have a copy of this book & not likely to build one - will have a look when I get home.

Nigel B.

Thread: Kennedy Hacksaw bearing replacement
11/04/2022 08:17:28

Tumble dryers and washing machines use very small drive pulleys with fairly extreme wrap around, spring-loaded adjusters and ony 16-20mm polydrive belts as I recall.

Some domestic machines use a stretchable poly-vee belt & do away with the tensioner. The grooves for the belt are ground directly into the motor shaft & the drum is plain (no grooves), so they operate much as has being suggested for the Kennedy modification.

At my previous employment we modified some of the belt building machines at a belt manufacturer to make the stretchable poly-vee belts for tumble dryers, adding a closed loop tensioner to apply the stretchable cord at a preset tension onto the rubber base layer. Normal belts used a different, non-stretching, cord - Kevlar IIRC. The belt building machines were modified manual Binns & Berry centre lathes that were converted to basic CNC operation, the cord being applied using the screwcutting cycle to get the required cord spacing.

The belts were manufactured as tubes about 2 metres long which, after vulcanising, were slit into the required width belts on another modified lathe that had Stanley knife blades mounted on the toolpost.

The issues I had when designing poly-vee drives were mainly due to the tension required to get them to drive properly without wearing out too quickly. Inadequate tension lead to the flanks of the vees on the belt wearing and, due to the narrowness of the vees, they soon bottomed out in the grooves and slipped. Short centre distances didn't help either, reducing the contact arc on the smaller pulley. High belt tension + plain bushes = likely short bearing life !

The OP's comment about the original belt not being very flexible suggests that it is old. The Kennedy I inherited from my father was incomplete & didn't come with a belt. I mangaged to get a new replacement from the bearing supplier we used at work & my recollection is that it was very flexible. Can't say how it performed, though, as I found one of the Taiwanese 6x4 bandsaws locally in a small ad & refurbished that rather than the Kennedy, which was subsequently sold still incomplete. From memory the replacement flat belt was some sort of plastic compound & was green on the outside & yellow on the driving side.

Nigel B.

Thread: Central Heating Control
10/04/2022 13:03:00

some older systems were down towards the 20% mark

Yet some modern systems are up around 90% or more ? IIRC my condensing system boiler is over 90% efficient, with the flue gas being barely warm.

My house was built with a living flame gas fire in the living room that is more about effect than efficiency - less than 30% - it rarely gets turned on. But modern versions can be up to 94% & if I wanted to use a fire instead of the CH I would look to changing it.

Actually thinking of replacing it with a solid fuel fire, as (unusually for a fairly modern house (1989 build)) there is a proper fireback & chimney behind the living flame fire & I could then heat one room independantly of gas or electricity should the need arise. Like the current gas fire, running costs & pollution would be zero if it wasn't operating.

Nigel B.

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