Member postings for mgnbuk

And he looked like he knew his welding. To get a weld so well done the slag just drops off like that is not easy.

That big oil cooled welder will help - there was a much smaller "Oxford" oil cooled welder where I started my apprenticeship & that even made my welding look good - no comparison with cheapy aircooled buzz boxes. Using Oerlikon electrodes with the Oxford the slag would start to curl up from the starting point before a decent run was completed & just fall off if left to cool.

I can appreciate the workmanship and ability to work with such (by Western standards) basic facilities, but I cringe every time they drop or drag machined parts on a concrete floor - surely a bit of wood doesn't cost the earth in Pakistan ?

Close-ups of the big end journals showed very heavy wear that I doubt would "polish out" with a bit of oiled emery cloth. No doubt 2 doors down from the "crankshaft repair guy" is the "oversize shell bearing guy" who makes up suitable bearings to fit the repaired cranks.

There are numerous videos of all kinds of small manufacturing facilities in that area that I find to be rather compelling in a vaguely horrified kind of way. I would expect that a lot of the people engaged in such activities don't get to an old age for a great many reasons.

The lathes featured seem to be locally manufactured. I had thought they would be Chinese, but a quick Google brought up 3 different makers in the Lahore area. All belt drive headstocks appear to the norm, as do home made brazed carbide tools.

Nigel B.

Linn Tools

Ebay shop, with a physical address shown on the "about" page.

Nigel B.

I used M-DRO three times for work - 2 installations using a basic 2 axis display with one (Harrison lathe) using glass scales and the other (Tool pre-setter) using magnetic scales + another single axis basic counter with a magnetic slide unit on a large belt sander table.

The Harrison installation was a replacement for a failed Anilam display & was cheaper than getting a replacement head unit for the Anilam. The pre-setter was a replacement for two failed independant capacitive readouts. The belt sander was replacement for a capacitive readout that really didn't get along with graphite dust.

The only "issues" I had were calibrating the magnetic scales - one was mounted directly on an aluminium extrusion, the other on a stainless steel bar in place of the Trimos capacitive scales & neither read accurately when checked with slip gauges as installed, requiring use of the linear calibration feature in the head unit. This was a "do it once" requirement, so not really a problem. The head unit did fail to start up after a lengthy period of disuse once, but an e-mail to M-DRO got the issue sorted promptly (there was a "hidden" reset button ). The magnetic scale on th belt sander occasionally mis-read due to build-up of fine metallic dust on the scale (some man-made graphite has iron filings in the mix to increase strength) - easliy cured with a puff of compressed air.

For home use I have a Chinese Jingce 3 axis head unit & 5 micron glass scales for my FB2 clone milling machine. Only had it rigged up off the machine to make sure that it worked on arrival so far. I went this route because it was around half the price of an M-DRO equivalent & my pockets are not as deep as my former employer ! Time will tell if that was a false economy.

WRT resolution - the basic Heidenhain two axis systems used by Bridegport on manual turret mills were 10 micron resolution. Can't recall anyone suggesting that these were not adequate, so 5 micron should be more than adequate for a basic mill.

Nigel B.

With these more detailed measurements, I’m guessing that it’s a new motor needed.

That does look rather terminal.

Depending on the cost of a replacement motor, it might be worth considering replacing the entire drive arrangement with a 3 phase motor + VFD. A bit more "engineering" to get that fitted, but probably a more reliable long term solution if done properly. It would be annoying to replace the DC motor & then have, say, the drive go down in a short time if it has been stressed by the current motor situation.

Nigel B.

Two Myford bed mounted capstan units, a cut-off slide, a cross-slide mounted capstan unit + capstan tooling on Ebay at the moment - search "Myford" & set "Newly listed" then scroll down.

Nigel B.

I have done a (small amount) of digging on this, mainly because I have a bit of a "DDR fetish".

Googling the visible model number on the picture above gets several pictorial hits in German, most being obsolete sales listings. Obviously used examples are frequently heavily sawdust encrusted & there are couple that are shown attached to woodworking lathes. This listing includes a picture of the original chuck box, with pictures of turned wooden objects & also a picture of the chuck that I think I can see an adapter bush fitted into the back of the chuck - the faceplate alongside has a much smaller mounting thread.

So it may be that the M32x1.5 thread is provided to make the chuck a "universal" item, being adapted to fit the lathe spindle nose with a bush (M32z1.5 outside, lathe spindle thread inside) as required.

Nigel B.

To see the pictures, click on the greyed-out image that says "geloescht" & the original pictures appear. Scroll through to get to the chuck packaging etc.

Edited By mgnbuk on 14/02/2023 16:29:57

Is the thread for a spindle nose mount, or in the operating part that moves the jaws ?

Power operated chucks have fine pitch threads in the part that moves the jaws for a connecting tube running through the spindle to the hydraulic or electric actuator mounted on the back of the spindle.

Nigel B

I'm against funding freebies for motorcycle fans when nurses are being asked to pay for inflation.....

Should anyone expect the taxpayer or Insurance companies to cough up when fans don't?

How much do the visitors who come to NI for the motorcycle events contribute to the economy there ? Ferries, accomodation, hospitality, fuel etc. I would expect that the extra tax revenues generated by such events would outweigh any investment by the NI Tourist authorities. Greater tax take = more money in the coffers to pay nurses more ?

Nigel B.

The bevel gear drive to the knee elevating screw looks rather like the flywheel & driven gear from a hand powered pillar drill of the type sometimes seen in older blacksmiths shops, but used in reverse (geared down, rather than geared up).

The photos are reasonably hi res if you open them in new tabs & zoom in. The knee also appears to be a fabrication when zoomed in on.

Too far away for me to consider, even if I did have room !

Nigel B.

I would disagree with the "made from castings" commenet - apart from the table & maybe the underslide this appears to be largely fabricated to me.

On the view of the RHS of the machine (if you were stood in front of it) the welds can clearly be seen on the column, base & over arm. The overarm just appears to have a flat base sat on the flat column top, secured with a large bolt through a slot in the arm.

The Clarkson collet chuck looks to be of the 2MT type, with the threaded support collar & a small gap can be seen betweeen it and the spindle nose. I would think that there is a very good chance that the spindle is 2MT. Even if the collet chcuck is "built in" to the spindle, fitting other tooling would be possible using parallel shank tools in the collet chuck.

There does appear to be some movement capability to the spindle, as gib strip screws can be seen on the LHS of the front swivel slide behind the spindle "casting" & on the side view from the LHS of the machine there is what appears to be a leadscrew behind the spindle "casting". Can't see from the pictures posted how this screw would be turned, though, and it may be more of a fine spindle downfeed than useable for drilling.

The table seems rather narrow compared to the knee & I wonder if the builder used the table & underslide from a small horizontal milling machine & fabricated the rest to give a larger machining envelope than just putting a vertical head on a horizontal mill ?

Not sure why the seller calls it a horiziontal mill, though, as I can see no evidence of a horizontal spindle.

Nigel B.

I started with some Chinese brazed carbides,,,,less said about that the better!!!

Did you grind them first before use ?

All of these that I have come across (square section lathe or round section boring tools) have just been square section carbide blanks brazed to the shanks with no clearance angle ground in, as though they are supplied "semi finished". A couple of minutes finishing them off on a green grit wheel to put some clearances on makes them functional - if you used them straight out of the packet I would not expect very good results !

Nigel B.

The spindle mounted pulley set is free running on the spindle on an S7, not keyed - it runs on bronze bushes & there is an oil nipple in the pulley. Drive to the spindle comes from a Woodruff key in the bull gear, the bull gear being connected to the pulley cluster with the retractable half round dog that is mounted on the bull gear.

The Woodruff key is small IIRC - the parts list says it is a "No. 404" key - so there is a possibility that the key has been sheared trying to remove the chuck.

A 'pdf of the Super 7 manual is easily found with a quick Google. This includes the exploded parts diagrams at the back. Worthwhile downloading a copy for reference purposes.

I don't think it is recommended to remove chucks using the chuck key inserted in a pinion, as this can split the square end of the pinion or dmamage the pinion bore.

Nigel B.

I have a Chester mini lathe on the bench, so did a couple of checks on that from a resistances POV as a comparison - not exactly the same motor as the OP's, but the same type & application.

This motor has not been used - I bought the machine at a Chester open day on clearance, mechanically complete but without it's electrical box fitted. It has sat on the bench ever since awaiting something doing with it - only around 20 years so far !

Resistance between the input wires was around 18 ohms measured with a Fluke 77 multimeter (which showed 0.3 Ohms with the leads shorted), which is probably more than a larger motor would be (IIRC the Chester machine is rated at "350 watts" ). Resistance from either input wire to the motor mounting stud (I can't get to the motor shaft where it is) with the Fluke was around 18 Mega Ohms.

As I also have an insulation tester (Center 360 autoranging meter) I checked resistance to ground with that at 250V (34 Mega Ohms) and 500V (33 Mega Ohms). I trust the insulation tester results more than the DVM, but they are in line with what I woudl expect for a "good" motor. Given that the motor has been sat for so long in a largely unheated environment, the readings may improve if the motor was warmed through.

I would be wary of just going at the commutator without confiming that the windings are good - largely a waste of effort if there is a short, as skimming the com won't fix that. While I have not had one of these specific motors apart, I did a repair to a similar motor from my sister-in-law's mobility scooter after my brother was a pillock and damaged it. The commutaor on this was decidedly "skinny", with thin segments that didn't give a lot to play with to skim up. Also the windings were staked, not soldered, into the segments. and neither were the windings impregnated. The whole thing just said "made down to a price" to me and, while I got it usable again, I recommended that he get another motor in hand for when this one inevitably fails. I don't see a budget lathe motor being made to much better standards & would best describe them as "disposable"

HTH

Nigel B.

Electrical resistance between each motor wire and the housing was 1 ohm.

That doesn't sound right - there should be no connection between either of the input connections and the motor frame. One of the usual tests carried out on a motor (completely disconnected from the drive & sat in isolation) is with an insulation tester & with a 500 or 1000v test I would expect a minimum of several mega ohms between input wires & motor frame. 1 ohm with a multimeter suggests a pretty hard short. You could try repeating the input wires to frame resistance check with the motor disconnected from the drive to eliminate the wiring.

It is usual for a DC permanent magnet motor to act as a generator when rotated. It is also usual to check the motor out with it disconnected from the machine. For further tests I would look to dismantle the motor, as it is difficult (or impossible) to access the armature, commutator & brush gear adequately with the motor assembled.

Probably cheaper to buy a replacement motor than take it to a specialist, who would probably not be able do do anything more than check it anyway - no spares other than brushes are likely to be available & a rewind would be prohibitive.

Nigel B.

Check the DC motor for an internal short to ground.

After prolonged use, carbon brush dust can build up & short the brush holders to the case or coat the brush holder insulating base & cause a short between brushes.

I experienced this several times on industrial installations. Usually poor maintenance of blower filters led to coolant or oil getting in to the motor & the brush dust stuck to it, though occasionally it was just a build-up of dry dust. Initial light shorts would sometimes burn off with a flash-over that the drive would ride out, or trip with an "instantaneous overcurrent" alarm that would not reappear after recycling power to the drive (industrial DC drives have much more sophisticated fault monitoring than hobby items). Eventually, though, a hard short would develop that would stop the machine & this required a clean-out of the brush area with a fast evaporating degreaser - a dirty & awkward job accomplished through access openings around the brushgear - and fitting a new air filter. The drives usually survived this though, occasionally, a drive would fail - handily protecting the expensive semiconductor fuses that were in circuit supposed to protect it !

Nigel B.

Some one will wake up pretty quick when no dosh arrives!

Unlikely in my experience.

Stop the DD or don't renew & the magazines stop arriving when your paid-up period ends. I have not had any kind of follow up from any publisher when I have stopped a repeating DD subscription or chosen to ignore an annual subscription reminder.

Nigel B.

The method used for cylinder heads is to "sneak up" on the final torque in stages.

First "snug up" all the bolts by hand, then tighten to the first torque setting (llower than final setting) in the required sequence using the torque wrench. When all bolts are tightened to the first setting, reset the torque wrench to the next higher stage & repeat the tightening sequence. Then increase the torque wrench setting for subesquent stages & repeat. Some head bolts add another final stage of rotating the nut by a set number of degrees after the final torque is achieved, for which special degree discs are available

For example : my wife's BMW R65LS motorcycle cylinder head bolts torque sequence is stated in the factory manual to be achieved in 3 stages - 15Nm first, then 35NM & finally 40NM (+/-2 NM). The tightening sequence is also shown.

I try to apply a continuous, smoothly increasing, pressure while tightening & stop as soon as the wrench clicks. I don't do the tyre shop method of repeatedly pulling the wrench to click point after the initial click.

Difficult to know how accurate the wrench is without at ability to have it calibrated, but a rough check can be made with a spring balance & a bit of calculation according to the wrench handle length. The wrench setting screw should be backed off after use to prevent "setting" the internal spring during storage.

After setting the wrench, I try it on a bolt in the vice before actual use to ensure that it does actually click at what seems like a sensible figure - stripped a bolt once when it turned out the wrench mechanism had siezed in storage & would never have clicked !

HTH

Nigel B.

Edited By mgnbuk on 01/02/2023 12:31:06

That must be done for economy of manufacture I would think as performance must be compromised to make this work.

Doesn't appear to affect performance too much, as this is a method used by Honda on current bikes - taken from a description of the latest Hornet 750 :

It’s instantly apparent that the new Hornet’s engine takes a leaf from the Africa Twin’s book, sharing a similar Unicam setup – where a single overhead camshaft acts directly on the four intake valves and opens the four exhaust valves via a set of rockers – to give similar performance to a DOHC design but with fewer components and a more compact layout. Honda’s CRF450R motocross bikes have long adopted a similar setup.

Doubtless having to make fewer parts will reduce costs as well.

Nigel B.

Thta does look promising Julius & your video plays fine for me.

My "solution" for a Dremel mount is a work-in-progress & it won't be as "high tech" as Hopper's :

A 3D printed adapter to suit a Dickson toolpost - the photo has come in sideways, but it doesn't really matter.

The formation to mate with the toolpost fits very nicely & with 6 perimeters the print is solid enough to resist similar clamping lever forces to a steel holder. The printed M5 threads in the body & height adjuster required a tap running though them to remove a very small amount of plastic to get a screw to fit snugly. The thread for the Dremel needs work - the example above is M18x2, which is the nearest to the M19x2 or 1/2" x 12 thread usually quoted for the Dremel nose from the "standard" threads in FreeCad. I used this with the idea of opening up the thread with a tap (1/2" x 12 BSF, as M19 x 2 taps are pricey ! ), but will re-visit this aspect on the "Threads workbench" to try to define a custom thread that fits the tool without need for a tap.

Unfortunately my PC was stuffed by a failed Windows update on Saturday (thanks Microsoft ! ) & the 3D model was one of the files that the repairer hasn't saved (the nature of the failed restart after the update required specialst help - a unfortunate first for me & I wasn't up to date with backing up ), so will have to start the project again from scratch. Should go easier this time (until I get to the custom threading bit anyway) but I do need the practice with FreeCad !

Nigel B.

I did successfully improve the wear / bellmouthing on the jaws of the OE 4" Pratt direct mount chuck that came with my mid-60s ex-school Super 7 by employing a similar method to the Popular Science article.

I held a suiable length of 1/2" silver steel in the tailstock chuck & used fine valve lapping paste between the silver steel & the 3 jaw chuck jaws. IIRC this required a fair bit of pressure on the 3 jaw chuck jaws to get it to cut & I pushed / pulled the tailstock body with the spindle rotating to move the silver steel in and out of the jaws. It took a while & a couple of recharges of lapping paste but, eventually, there was a fresh witness mark on all 3 jaws right to the front edge. Checked by gripping a piece of 1/2" SS, runout was with a couple of thou TIR close to the jaws.

I felt it was a worthwhile excercise at the time, but do have a new Chinese 100mm chuck & backplate to hand to fit at some point - the Pratt is the better part of 60 years old now & nothing lasts forever !

Nigel B.