Member postings for Mike Poole

I think you will find that 2 of the screws on the gib adjusment side are longer and intended to lock the cross slide without playing any part in the slide adjusment, when slackened the slide should be in normal adjustment and tightening should lock the slide.

Mike

There appears to be two versions of the manual one has the mistake you have found corrected.

Mike

As I mentioned earlier I usually have a 4" threaded body PB mounted and the distance from the register face to front of jaw is about 73mm, the 5" TOS is 105mm, this is quite a lot of overhang on a small spindle and is the factor that concerns me more than weight. As a significant amount of work done in a homeworkshop is too big for the machines it is a tribute to all makes that it takes it in its stride, of course material removal rates usually match the precariousness of the setup but with care and sympathy for the abuse no harm is usually done. Some chucks I have are marked on the jaws to indicate the maximum allowed extension from the body but jaws sticking out are another danger as I often use my hand on the chuck as a brake (probably bad practice) and doing this with jaws sticking out will propably result in the red stuff leaking out.

Mike

Slip ring motors were a common fitment on travelling overhead cranes in our press shop and toolroom, the rotor resistors were switched by a large drum switch to give smooth operation to the crane movments.The dies were stored outside in a die park with a travelling gantry crane, one night we came in and the dayshift had wired the long travel motors direct on as the resistor bank was unserviceable and spares unavailable. Standing on the gantry walkway 25ft up in the air when that started off felt like being in a cartoon when their feet run off and the body catches up later. We paid a few visits to the crane that night as the fuses did not like direct on starting.

Mike

I was at a show and Myford confirmed that the lathe I was looking at was made in the UK it looked very nice and a worthy successor to the Nottingham machines. Price is the only downside. A lot of work must have gone into getting the Myford back on sale and I hope some people will choose to afford one. I feel Myford are not blowing their own trumpet enough at getting the lathes manufactured again as the beliefs of some people on this forum show the word has not got out too well.

Mike

I have a 5" for my 7R but I only use it when it is needed as it makes some tasks a bit easier, everyday wear is the classic 4". I find the 5" requires extra awareness of the jaw cross slide clearance particularly with jaws extended out of the body. I agree it makes the Myford look over chucked but it can be useful and the 6" 4 jaw could probably do anything the 5"SC could do.

Mike

The only factor against climb milling is the existence of backlash in the table drive, the use of ballscrews usually solves this at a stroke but other solutions are available, anti backlash nuts can be spring loaded or hydraulically loaded to eliminate any lost motion, I even worked on an NC mill that used hydraulic rams to move the axes. Unfortunately serious backlash solutions are not often fitted on home type equipment, my humble VMC has a crude pinch screw to tighten the nut but any wear in the screw will soon result in tight or loose spots. I often do light climb milling for a finish cut and adopt Davids suggestion of using the locks to provide more resistance to the axis being dragged by the cutter but this relys on having some feel for the cutting forces versus the table drag. Backlash elimination tends to wear the screw but converting to ballscrews could be done even if CNC is not the final goal but costs a bit just to eliminate backlash. If backlash did not exist I think climb milling would be the mode of choice as all the theory is in favour of it.

Mike

When I wound motors in our winding shop we used oxy-acetylene to fuse the two wires into a small ball. To lace the windings we used flat cotton tape about 10mm wide and a piece of lewmex wire as a needle to thread it through the windings, systoflex heat resistant glass fibre based sleeving was used to sleeve joints.

Mike

Edited By Michael Poole on 05/10/2015 13:26:00

Manually operated machinery has become a niche product as even toolrooms which were the pinnacle of manual skills have gone down the CNC route. Industrial manufacturing has no place for manual machines so the manufacturers of high quality manual equipment have either moved on to CNC or gone out of business. When I worked in toolroom maintenance die sinking copy mills were being converted to CNC to skip the pattern/model shop and template section stages of die production. Planers were giving way to planomills which gave a massive increase in productivity. Manual machinery is enormously satisfying to use but today it is only the hobby engineer who gets a kick out of this. A few factories in China would seem to be able to satisfy the worldwide demand for manually operated machines at a price the hobby engineer can afford. The machinery that we lust after has never been affordable to the hobby engineer unless he had extraordinarily deep pockets, when I first developed a yen for a myford it cost £110 which seemed quite a lot of money at the time, the near £10,000 today still seems a lot of money and this was a machine aimed partly at the hobby engineer. Shaublin, Aciera and such machines never were in reach of the average man as new machines, and the people who have aquired good used machines are very lucky. I think it is unlikely now that much time and effort will be applied to making new concept manual machinery. The day will probably come when the hobby machinist gets a kick out of executing the program he has generated from his 3D cadcam software on his home CNC machine, for some this has already happened and one day Minnie and Tich will be made on your home machining centre.

Mike

Edited By Michael Poole on 27/09/2015 23:44:32

I worked on a very early NC machine built by EMI , the control system was valves, toroids and relays, it was still limping along in the mid to late '70s but the axis travel was getting shorter as we could not source replacement glass inductosyns and so moved the end ones to the damaged area.

Keller copy mills used a tracer to follow a model and each axis had 2 elctromagnetic clutches controlled from the tracer. The machinist would set the machine up and sit back to read his book. It could take a few days to mill a large body panel die.

Mike

Hi ega, I do not have first hand experience of the teco mincon drive but I had a little browse of a manual on line and as David mentions above it would appear they use the DC injection braking system, this might explain your difficulty in finding what to do with the braking resistor as this type of braking would not use a resistor. There are a few parameters to set to give the braking effect required for your application. DC injection can give a very powerful effect and is sometimes used as safety brake on things like drilling machines where an almost instant stop can be achieved. Used as an emergency stop for operator protection puts quite a high mechanical stress on the machine but a much milder effect can also be used.

Mike

Hi Vic,

Just to try and enlighten you on what your vfd is doing for you and help you to get the best from it. The supply is AC and is rectified to give a high voltage DC supply from which 3 phases can be created at any frequency you need for the speed you demand. The problem with trying to slow down quickly is the output stage of the inverter acts as an input back to the DC supply which will push the voltage higher, if the drive detects this it will try and dump this to an external resistor if fitted but if not fitted it will shut the drive down to protect itself. It looks as though your drive has a parameter 1-15 that can be set to slow the drive as rapidly as possible depending on the load, it may be worth trying this out as if you choose a fixed slowdown ramp it will have to be for the worst case scenario which will be the heaviest or fastest job you do. The great thing about VFDs is that they can be made to slow faster than a simple motor drive which unless a mechanical brake is fitted will always coast to a stop. With a resistor fitted to absorb the energy from the machine some quite savage rates of braking can be achieved. If the nose of the lathe takes screw on faceplates and chucks this may try to unscrew the faceplate when braking (just a possibility)

Mike

Depending on where you fit the x axis scale you may lose some y axis travel. Fitted to the rear you will lose some travel but the scale is out of the way, fitted to the front can be done but the scale will need substantial protection and can foul the knee handle, the lock stops will need reengineering or losing. Magnetic scales are probably the slimmest and will lose the minimum amount of travel if fitted to the rear and not cause any fouling with knee raise handle.

Mike

I have a couple of Norbar torque wrenches and as I knew the people in our torque tools calibration dept. I got them checked. It surprised me how hard it was to get a consistant reading from a click type wrench. the calibration guys had the feel for the calibration rig but my first tries were all over the place. I had thought of the click type as being reasonably idiot proof but it appears even they need the right feel to get consistant results. The calibration guys knew I would struggle to get consistant results so had a good laugh at my efforts. It turned out the Norbar wrenches had held their calibration well and gave good readings accross their range.

Mike

The end float is adjusted by the screwed collar on the left end of the spindle, it may be worth a little investigation as 2mm is quite a lot to suddenly appear, it may simply be the locking screw for the collar has come loose and allowed the collar to move.

Mike

The drawbar thread is often etched on the body of genuine Clarkson holders, can be hard to find and read though! If it is metric it usually has a groove machined at the drawbar end

Mike

Edited By Michael Poole on 26/08/2015 15:19:58

Edited By Michael Poole on 26/08/2015 15:22:16

Edited By Michael Poole on 26/08/2015 15:22:40

Duncan, I think you have said what I meant to say, I should read my scribbling with more care.

Mike

A single phase motor with a centrifugal switch will not reverse until it has slowed enough for the switch to reconnect so switching straight into reverse will not result in the chuck unscrewing, with many people using inverters to run their lathe it is possible to slow the motor much more quickly than letting it coast to a stop, if the slow down ramp is very short a chuck that has not been nipped on or taken a reasonable cut could come loose. Someone will quote the story of switching straight into reverse and seeing the chuck unscrew and slamming back into forward with the chuck locking on to the nose and the backplate having to be machined off the nose. I often do a bit of light turning in reverse and have not yet had the chuck unscrew but it is always in the back of my mind when doing it. I programmed a conservative slowdown on my lathe inverter but if you go too far it is annoying waiting for it to stop. Just running in reverse to reposition the carriage is most unlikely to ever be a problem.

Mike

If you are cutting metric threads on an imperial lathe you will not want to disengage the clasp nut, so you will need to reverse the lathe to get back to the start point and take the next cut. On a lathe with screw on type chucks cutting in reverse could unscrew the chuck.

Mike

A firm grip at all times is essential with all power tools, you should be able to hold most power tools if they kick or grab unexpectedly. Loose additional handles are often supplied with power tools and these help maintain a good grip and firm control of the tool when fitted. The tools I have found to be the most scary are electric planes and routers, they are so sharp and fast that any bits of you vanish in a trice never to be found again. Metal working kit seems to be bit more friendly to me, but never underestimate its ability to take a bite out of you. Metal and woodworking machines are untroubled by bits of human offered to them they will remove them with ease. I hope I have the right blend of confidence and respect that has so far kept me intact, just a few knock and cuts when not being as focused as I should be. The last reminder was getting hit on the end of my index finger by a chuck jaw extended beyond the chuck body, they disappear at speed but you can certainly feel them! Still got a numb spot many months after the cut and split nail healed.

Mike