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: Level lathe set up|
Surely the bed will be flat if no external load is applied?
Maybe, maybe not. That could depend, for example, on whether the bed casting was properly stress relieved at the point of manufacture - it may have been naturally straight at the time it was built & gradually move over time as the stresses worked themselves out over time. In that case, it would need "un-twisting" when you installed it later.
I used to work for a company that rebuilt & updated CNC machine tools & cannot recall any vertical borer, large lathe or milling machine installation that would sit naturally "true" - all required bolting to the floor (or other foundation, depending on the sub-soil & floor concrete depth) & carefull tweaking of the levelling bolts to achieve the required "levels". In "our" factory, which was purpose built, the floor was 600mm thick concrete & the machines being worked upon were bolted down with chemically anchored high tensile studding.
It may well be that a small machine, like a mini-lathe, would sit naturally "true" if the casting was properly stress relieved before maching, but I suspect that anything bigger would be prone to movement - castings are a lot more flexible in practice than you might think.
Boxford used to stress relieve the South Bend style beds naturally over many months. They sat stacked on pallets in the yard & were hosed down daily if it wasn't raining. After 3 months or so, the castings were shot blasted with steel slag, "topped & tailed" on a planer & put outside for another 3 months. Then another shotblast, filled & painted before final machining. The later geared head beds came in supposedly stress relieved from the foundry - they were found to "move" during heat treatment (induction hardening of the slideways) & after a lot of trials & jig was used to bend the bed hollow before it was hardened. After hardening, the tension was released, then re-applied at a lower torque setting before grinding - the finish ground bed then came off straight.
On the cabinet mounted lathes, the beds were mounted onto a bed of Isopon polyester paste on the base fabrication & set true with a level. The excess paste that exuded as the bed was pulled down was trimmed off before it hardened.
No need to be like that Nigel.
Apologies for any offence, Russell - my remark was intended to be light-hearted & I forgot to add the "smiley".
The object of "levelling" the lathe is to return it to the state that the manufacturer built the machine in when they documented that it met the accuracy standards. This will then allow the user to confirm (or otherwise) the manufacturer's documented readings. I do not believe that the "Method" (be it Rollie's dads or Rolly's dads) will do that. That does not make it an unreasonable method of checking headstock alignment if a suitable test bar in not available, but after the bed has been set "level" .How does this "Method" differentiate between a twisted bed and a mis-aligned headstock ? There is more to using a lathe than just turning parallel - will twisting the bed to get parallel turning when the headstock is mis-aligned cause problems with the tailstock alignment at different distances from the chuck that put drills off centre, for example ?
Is £40 unreasonable for a piece of precision test equipment ? Is it really a lot in terms of the cost of the lathe, the tooling require to be able to use the lathe & the other measuring equipment to check the output from the lathe ? As to how often it is used, that depends on how often you wish to use it & that will depend on how often the machine moves out of "level". One machine I worked on stated in the manual that the "levels" were to be checked monthly after installation until there was no change between two consecutive checks, then the checks were to be moved out to 6 monthly.
You lot are slacking - 16 posts in before "Rolly's Dad's Method" came up !
Buy or borrow a proper level & do it right.
|Thread: Imperial tee bolts for Myford?|
It's more difficult to get non-metric fasteners these days
Quite easy to get BSW, BSF, UNC & UNF cap screws, grub screws, set screws & bolts from Cromwell Tools in a wide range of sizes. Delivery has always been ex-stock (same as metric) when I have had cause to have to get any.
Don't recall seeing Imperial Myford tee nuts in the catalogue, though.
|Thread: Level lathe set up|
There are slant bed lathe which are definitely at an angle front to back but probably still levelish lengthwise.
Slant bed lathes are leveled front-to-back using a fixture held in the turret that puts the level errr.... level.
Sometimes this is provided with the machine as part of the original equipment, sometimes the installation technician brings the factory tool along with him (and takes it away again) or, in my case, you make one when you get a second hand machine.
When (reasonable quality) lathes are manufactured, the alignments are set with the bed set in a known condition. Setting the bed back to that known condition on installation should, therefore, bring all the other alignments back to the values shown on the inspection record. In the greater (industrial) scheme of things, a precision level is cheap & easy to use, so using one to set the bed level is easy for both machine builder & end user to get to a known condition.
A 0.05mm/metre level can be obtained from Ebay from £40-ish (Item 272295866038 for example), which isn't a great deal for a precision measuring device.
Doubtless there will be other posts along shortly extolling the virtues of "Rollies Dad's Method" (whoever Rollie was ?) to set up a lathe & decrying the use of a precision level in the home workshop - to each their own !
|Thread: Aircraft General Discussion|
Not aware of any air shows locally but may be wrong.
Local publicity for today's Blackpool Airshow left a bit to be desired then !
Looks like the weather was nice for it.
|Thread: KWh question|
Today i get a letter from EDF saying they will fit a Smart Meter
I had my meter replaced a couple of months ago. A "standard" electronic meter was fitted in place of the old mechanical one & I mentioned Smart meters to the installation chap. He wouldn't be drawn on the matter, beyond saying that he wasn't fitting a Smart meter at that moment & suggested that I would be well advised to research them thoroughly before going down that route if I had a mind to.
|Thread: levelling a shaper?|
My 8" Boxford (fixed table) is bolted to the concrete garage floor & was levelled with a precison level, as I had access to levels through my employer at the time.
The "bolts" are actually lengths of studding locked into the floor using expanding anchors & the machine was levelled with nuts on the studding & locked into position with nuts above the base. The machine sits an inch or so above the floor & was then grouted in - a frame was built around the base & filled up with a specialist machine tool grouting compound. This only happened as I had half a bag of epoxy grout left over after an installation for work & it "went off" quite quickly after the bag was opened. This grout is a form of sand & cement mix, but it expands slightly on curing - probably one of these products **LINK** .
Somebody will have fun taking this out when I depart !
|Thread: Does this count as a manual tool?|
You wouldn't want to startle the operator and have him turn quickly..
This is, apparently, why you don't see hand-held waterjet cutters any more
(not that I ever saw one in the first place !).
|Thread: 4 Jaw Chuck clean it or not?|
You have no need to remove it from the back plate. Doing so will not show any innards of the chuck and there will be nothing to clean or lubricate
By the look of it, you may need to remove the backplate to remove the jaw screw retainers ?
Can't see for certain from the photos, but many 4 jaw chucks have the jaw screws retained axially by a thrust "plug" that engages with a groove in the screw. These plugs are inserted from the rear of the chuck body & removal (to allow removal of the screws) will require the removal of the backplate.
But it's nothing to get worked up about - it was made as individual parts, should dismantle back to those same individual parts for cleaning up & then re-assemble again.
|Thread: Squeaky 7x12 bearings|
Roiller bearings need very little preload.
Depends on the application. Timken used to (maybe still do ?) make a taper roller bearing called a Hydra-rib that allowed the preload to be changed "on the fly" using hydraulic pressure. De Vleig borers used them - in low range (where heavy loads could be expected) the pressure was increased to run a higher preload. In high range a lower pressure was used so bearing heating was reduced at higher speeds & higher stiffness was not required.
You should only fill the bearings about 40% with grease.
Doesn't matter as much with taper rollers. Unlike ball bearings, which "churn" excess grease within the bearing causing overheating, taper rollers "pump" from one side to the other so the grease gets expelled in normal operation. More of an issue with taper rollers is keeping them greased - hence the usual provison of some form of re-greasing arrangement on TR applications where many BB applications are greased-for-life.
I would expect over tight bearings to start to get warm quite quickly, getting uncomfortably hot at higher speeds after longer running. Some MTBs use the headstock temperature after running at a particular speed for a particular time as the method of setting optimum pre-load - too cool, increase - too warm, decrease.
|Thread: Motorcycle General Discussion|
Nice job there TG.
My brother-in-law had a late model "pink" TY250 when they were current.
I started with a twin-shock SWM (280 Rotax), then a monoshock Armstrong (280 Rotax), followed by a JCM 240 Europa & finally a twin-shock Honda TLR 250. My wife had a Fantic 300 twin-shock & a Beta 240 mono. Trials used to be very popular in Yorkshire, but I don't think it is as much these days - finding suitable land & getting permission to use it was always a problem, which has only got worse.
After 5 years or so competing at club level, I gave up trials when the Honda was stolen some 20 years ago.
|Thread: "Vintage" CNC|
Anyone remember plugboard capstan lathes. They always looked like black magic to me
Oh yes - very profitable for me as an apprentice was a Hepworth plugboard capstan lathe. This used a Herbert (No. 4 Pre-optive IIRC) as it's base with a Hepworth plugboard control. The control had a couple of dozen TTL logic circuit boards, which were frequently "iffy" - many boring hours sat waiting for an intermittent fault to appear to use signal injectors, heat gun, freezing sprays etc. to try & identify where the problem was. Usually though (& this was the profitable bit for me) I had to take the suspect board to Hepworth's works outside Holmfirth (our works was in Brighouse) to have it run through the test rigs there. I ran a sub-250cc motorcycle & got the small car mileage rate, so a nice run out in the middle of the day paid for my fuel for the week.
In the late '80s I comissioned & trained on a couple of new CNC VMCs installed in Czechoslokvakia (pre the end of Communism). One of the milling machines there used 35mm movie film as the "tape" - a very basic control moved the axes in sequence to limit switches, the relevant switches being punched onto the "tape", which was then spliced to be an endless loop. The programmers I was working with brought out the reel of film that they had been given to use and, holding it up to the light to see a few frames, it was obviously an old propoganda film, with an actor made up as Lenin on a podium giving an animated speech.
but they were a plumbers nightmare, blowing seals and leaking and then the concensus was to concentrate on servo and stepper controls
And hot and noisey, as well as taking up a large amount of room for the oil tanks, coolers etc. And very, very finicky about cleanliness - machines were shipped with "flushing blocks", which were used to replace the servo valves to allow the system to be flushed for several hours if the hydaulics had to be worked on.
But before reliable, high power electronic switching devices, there was little option if you wanted a high torque servo drive. Mostly hydraulic motors driving ballscrews, but some (certainly some Newall borers, probably others) used hydraulic cylinders. Taken plenty off & replaced them with modern electric servo drives (and managed to interface a modern control to the old servo valves on a Newall cylinder driven jig borer) in my last job.
Mylar tapes were only used for the Diagnostic and Parameter tapes on the machines I was set on to learn the maintenance of in 1977 - much too expensive to use for day-to-day operation. BTW, if you come across any unused rolls of 1" tape, don't bin it - it hasn't been made for ages & there are still a few die-hard users who will pay whatever you want to ask to get hold of it !
Through holes to bolt it to the desk to stop it growing legs ?
|Thread: How do I adjust the quill?|
Is it this one ?
This came from the link on this page : **LINK**
|Thread: Bridgeport EZtrack|
as the feed screws will need changing to standard acme.
Ballscrews are quite useable manually with handwheels - some ballscrew companies (Hiwin for one) did conversion kits to bolt-on to manual Bridgeports to replace the acmes.
|Thread: DIY hearth|
My employer is currently making wood fired pizza ovens using a perlite or vermiculite & Portland cement mix. The cured shells have proven to be quite weak, prone to cracking & appear to be hygroscopic - the initial experimental attempts that didn't crack during production have failed after a few firing cycles, possibly due to getting damp during periods of non-use & then heating up too quickly when next used. IIRC he did try adding ground-up oil-absorbent clay granules as a binder at one point, but I think the recent builds have been without. The shell wall for these items is around 40 -50 mm thick. I think he is on Mark 5 or 6 at the moment - the latest "mod" being to tile & grout the outer surface to try & improve rain resistance (earlier versions had several coats of masonary paint). The earlier variations were experiments with the mix to get better consistency after failures either during manufacture or after a few uses. He is using a Belle cement mixer to mix the stuff & allows it several days to dry out before removing the forms & an intial gentle firing.
Don't know if that will help or not - but may point towards having to experiment with mixes etc. to get an acceptable result.
'2 keys', why 2 keys?
Easier / quicker to set with a key in each of the opposing jaws - you can only push with a jaw, so using one key means having to spin the chuck 180 degrees to get to the other side if that is where the push is required. Using 2 keys allows you to push from either side as required without having to rotate the chuck.
Nigel B (another who was taught to use a 4 jaw independant in an apprentice training school)
|Thread: The diesel controversy|
They can and do, but they aren't supposed to.
HMG say otherwise - look at the column "Goods vehicles (not more than 7.5 tonnes maximum laden weight)" which shows motorway speed limt as 70 mph. This is the same as "Cars, motorcycles, car-derived vans and dual-purpose vehicles", "Motorhomes or motor caravans (not more than 3.05 tonnes maximum unladen weight)" , "Motorhomes or motor caravans (more than 3.05 tonnes maximum unladen weight)" and "Buses, coaches and minibuses (not more than 12 metres overall length)" - all are 70 mph on motorways.
Dual carriage ways & single carriage ways are another matter, but for motorhomes "not more than 3.05 tonnes maximum unladen weight" sets the limits, not maximum permitted weight.
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