Thread: 260 ATM 19754 project
7th Oct 2010, 11:04 PM #1
260 ATM 19754 project
I thought I contribute some pics of my project... There is still a lot to do....
The wheels are just temporary whilst I am rebuilding it, will be replaced by levelling feet once I find a firm place for it
These are PowerTwist Link belts, run much quiter than the spliced V belts, and no need to remove spindle anymore..
The control box I just made, from a plastic junction box and some scrap Ally sheet. Top left is the detachable control panel from the VSD. Top right a keyswitch to bypass the safety interlock switch, below the display for spindle rpm,. Bottom laft emergency stop, middle fwd/stop/reverse switch, right speed control knob.
The rebuilt electrics panel...
... before putting it back
The Omron/Yaskawa VSD I bought from eBay, new old stock from France for under $120 including postage. Arrived in under 10 days. And even works. Otherwise, only the two pushbuttons at the frontplate are still Hercus original, and of course the repainted steel frame itself.
The green in from a Bunnings rattlecan, the closest matching Killrust epoxy. Very slow drying..... I could not resist to add some contrast: Red engine paint also from the green store.
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8th Oct 2010, 11:02 AM #2
Thanks for sharingcheers
A society grows great when old men plant trees whose shade they’ll never sit in. (Greek proverb)
8th Oct 2010, 10:12 PM #3
wow thank you for showing your machine seeing 260's like this restored makes me want restore one of my ownhappy turning
9th Oct 2010, 11:48 PM #4
Dunno about anyone else, but I can't see any pictures. Is it just me?
10th Oct 2010, 08:29 AM #5
got to put your glasses on ken its all good here
10th Oct 2010, 11:47 AM #6
Congratulations. That looks magnificent. Care to share some of your restoration techniques?
eg, paint removal, bare metal polishing, paint application etc. Please tell us more about the VSD, ie brand, eBay seller. Are these things easy to set up, I have been living under a cloud and have no experience with them.
11th Oct 2010, 03:22 PM #7
> Care to share some of your restoration techniques?
This is not really a restoration, it's more like a brush-up. This lathe has barely been used for maybe 50 or 100 hours since it was made in 1988. The fellow I bought it from kept it under a blanket for almost 20 yaers. He received it as wages when the company he worked for closed. He still had the price list and the brochures from when the company bought the lathe in 88 (I posted them in earlier messages). There was surface rust on everything unpainted. And the paint itself was in bad shape, especially where it was exposed to oil all the years. But the ways were like new and complentely unworn, and all parts that usually would show evidence of wear are like brand new. It came with the original 3 phase motor in a box, and with a single phase motor installed that I do not want or need. Virtually new Burnerd 4 and 3 jaw chucks, as well as an unused vertical milling slide with vise and some tooling. So the starting conditions were very favorable. Else it would not have been worth the $4000 that I paid for it. For that sort of money one could buy a brand new Chinese 12" lathe with all bells and whistles. But I wanted a good old iron lathe, without spending the outrageous money needed for a new Myford. I am not a collector, I want to use this 260. I have owned a smaller 100mm swing lathe since 1986 which I willl keep for smaller precision jobs, it is fitted with VSD and 2-axis DRO. The 3 times heavier Hercus 260 is for the larger jobs.
> eg, paint removal, bare metal polishing, paint application etc.
I did choose to stick to the Hercus green, not because I like it, but because not all parts did need a new coat of paint. The most in need of a new coat was the cabinet, and the apron which was very poorly painted in the first place and thus the paint suffered from the long exposure to oil, eg it simply peeled off exposing the red primer and the white filler. Also, everything had to come apart to wash out the gunked up old gunked up oil (I suspect part of it was the original protective wax/oil mix that Hercus had applied at the factory was also still there, I can tell because in some places some Hercus green paint overspray was still on top of it - the guys apparenty finish coated during assembly).
Removal of old paint where necessary was done with emery paper. The apron took particularly long. I used primer, then Bunnings rattlecan Killrust "wilderness" tint. It is an epoxy paint that I hope will resist oils etc and appears to be pretty tough and chip resistant. It is very slow drying stuff, 18 hours between recoats, and several weeks to halfway cure. But came out reasonably well. I just used some fine wet/dry paper between coats to get rid of imperfections due to dust. The can needs to be warmed in hot water before use, else the paint will not flow as it should on a colder day.
All the red items I did with White Knight Hight Temperature engine enamel and baked it in the kitchen oven (wife was overeas on holidays). This paint is much easier to apply and dries very quickly, re-paints in 1 hour. This paint is oil proof, but more brittle and chips easily.
The cabinet I had to thoroughly sand with an orbital sander. Especially the drip pan which is made of very this gauge steel. I used Killrust "Wilderness" from a tin. The canbinet without priming, the drip pan with previous priming. I stffed up my first coat. I tried to use a small roller, but it ended up with millions of small bubbles, and this despite the paint taking about two days to feel dry to touch. And I had it indoors in the heated living room for painting (wife was away...) I had to let it harden a few days and sand it halfway off again. The next coats I brushed on, but not before heating the paint can in hot water. Much better, but you see it was brushed if you look closely.
To give you an idea on the difference in tone between "Hercus green" and "Bunnings Killrust Wilderness green" look at the first picture that I posted. The square panel where left in the cabinet wher the start and stop buttons are, that is still Hercus green, All around it is Wilderness green. Same tone, pretty close, but..... On a large surface you notice with ease. But look at the apron picture: The spokes of the big handwheel are still the original Hercus green, the apron itself is "Wilderness". Can you see a difference? I can't even when standing in front. The saddle though (I left that original Hercus green) does contrast with the Apron (Wilderness green).
If I could do it all over again, I would rather spend the money for some professional machine paint whatever the color, and repaint everything. Or use tractor paint which is good quality too. Or bring it to a car painter and have it done. Then again, it is useful to repeat to myself thet I really want to use it, not just look at it, so it does not matter.
> Please tell us more about the VSD, ie brand, eBay seller. Are these things
> easy to set up, I have been living under a cloud and have no experience with
I have VSD's on my other EMCO lathe (Siemens Micromaster Vector), on my Waldown drill press (Lenze smd), on my Chinese X3 mill (Telemechanique Altivar 18). For me it was clear only a VSD would do for the Hercus. I am not choosy regarding brand so long as the price is right. I refuse to pay list price for such items.
Looking up eBay and especially checking its sites for European countries, I ended up being the winning biider for a brand new old stock Omron/Yaskawa Varispeed 7 of 3/4HP. Cost me just under $120 including postage, when exactly the same unit is in the RS components catalog for AU$720. For that price difference I can do without a warranty anytime.
The original 3 phase motor on my Hercus 260 is a 3/4HP TEFC made by Elektrokovina (in former Yugoslavia), 0.55kW, 1405rpm ay 50Hz. It can be wired delta 240V or Wye 415V, so it is ideally suited for a 240V VSD conversion. I have read on this forum though, that older Hercus 260 were fitted with a different motor for Wye hookup only.
I am used from my other small lathe to have the motor controls above the headstock, that is why I made the same again.
Except my very first VSD 8 years ago, I bought all my VSD's like this. All were and still are working just fine at a fraction the local cost. But I am an Electrical Engineer by trade and know what to look out for and what to avoid. If you have no experience, I suggest you go to a local dealer in electric motors near you, explain what you want it for, and take what he recommends. That way you can go back and ask for help if it does not work as expected, and a small local dealer will take the time to help you the large ones not and if you buy from eBay forget support.
IF you still consider to buy a VFD from eBay, I have a few tips that may help:
- European single phase VFD's are 240V like ours, so no problem, American single phase VFD's can be 100/110V or 200/220V, be careful
- Do not search for VSD (Variable Speed Drive), that is only the Australian name for it. Search for VFD (Variable Frequency Drive), search in the German eBay for "Frequenzumrichter" and "Frequenzumformer" and in the French eBay for "Variateur de Vitesse". You find more choice and better prices in Europe than here, because there is more industry over there using them in larger numbers.
- for a lathe, only go for a "sensorless vector" technology VSD. Simple V/Hz types are about one third chheaper, but more suited to driving airconditioning fans rather than machine tools. For a lathe you want a wide speed range, and that implies a Vector drive.
- Before bidding on a VSD, go to the manufacturer's website and see if you can download the installation and operator's manuals for the model in question. If you cannot, then stay away, it's either totally obsolete or otherwise fishy and nobody will support you if you have problems.
- Never put a switch or fuse between the VSD and the motor. All motor controls happen via low voltage wires between control panel and VSD.
Still left to do:
- Lathe alignment, once it comes to its final location.
- New quick change toolpost, on my old lathe I have a homemade Grosz clamp type toolpost with homemade dovetailed toolholders. Need to make one more toolpost of the same, so I can swap toolholders between the two lathes.
- Need to make a chip guard from Perspex or the like
- need to make or find a collet chuck. This lathe came with the drawbar and handwheel for 4C collets but no collets. And 4C is really an odd American size hard to get and if you find ir far too expensive. I am thinking of making an ER40 collet chuck instead. Only problem, this metric Hercus cannot cut its own spindle taper which is 8TPI. My other lathe is metric too.
11th Oct 2010, 05:05 PM #8
Some Before pics:
The red stuff is the original Hercus primer. The green paint was attacked by oil and scrapes off by fingernal. Yak.
Everything unprotected with surface rust. I took it all apart, and put bit for bit in my smaller lathe, and polish surfaces with emery cloth. The result is like new.
This is the original electrical panel for 3-phase.
22nd Oct 2010, 03:05 PM #9
Today I had some spare time. I installed the sensor for the tachometer. It is a low cost inductive sesor from Rikon/Taiwan. I bought it from eBay for 12 AUD all up inclusive cable and postage. It has a built-in light that flashes red when the sensor detects something metallic passic in front of it. The one I choose has a sensing distance of 0 to 4mm. I have it detect the grub screw that fixes the spindle bearing preload adjustment nut. It was the most suitable place I could find. This means it detects one puls per spindle revolution. For display I use an OMRON H7ER-SBV tachometer with LCD display.I got that from eBay Australia as new old stock for AU$ 41 allup including postage. This tachometer is small and can handle just about any number of pulses per revolution, there are three switches to set. The only disadvantage is in my opinion that iy is a small display and harer to read than an LED display. But at that price one cannot argue, it was a bargain and it works.
Pic 1, overall view. I milled a flat onto the red bearing cover to attach the 3mm thicj Aluminium bracket I made to mount the sensor. I used a longer than standard grubscrew for the preload adjuster nut, and faced this grubscrew to lenght such as be detectable by the inductive sensor. The sensor itself can move in its bracket about +/- 1mm for fine adjustment. But that was not needed, the sensing distance is very uncritical.
The same seen from top
.... closer.... the red hue is the sensor light indicating it sees the grubscrew....
..... closer ....
.... closer ....
... closer ....
VSD frequency set to 50Hz, the rpm meter shows 1740rpm with the idependant 4-jaw chuck installed
close-up of displays, 50Hz VFD frequency and 1800 spindle rpm (at the highest speed belt setting)
This is the top speed, at 101Hz VSD frequency 3360rpm. I have to add that the bearings do get quite warm. I found it very difficult to adjust bearing preload on this machine. Normally I set preload such as that the headstock gets hot to touch after about 30 minutes running at the top speed. But here, I have the feeling the berings are pretty loose and still get quite hot. Maybe this lathe is just not designed to run much faster than some 2500rpm. I shall find out soon. Also there are some vibrations at higher rpm, that seem to originate from not properly balanced spindle/cone pulley/backgear. Even with the spindle belt loose there still are some vibrations, pointing to a not too well balanced layshaft. And even with that belt removed, the motor spinning on its own, there still are some residual vibrations pointing to a not too well balanced motor. This is definitely not a Hardinge or a Schaublin.
This is a look inside the junction box I use as control box. Bottom right is the OMRON tachometer, bottom left the VSD front panel with the green RJ interface connector.
Seen from behind, to show the various cables hanging loosely down
Another view from behin, this time with the top cover flipped open, to show why I left the cables hanging loosely
Hope you find this interesting. It is just what I came up with in a short time to get some rpm information. There certainly are more elegant solutions that I just did nit think of. On my older Emco lathe, I use the Shumatech DRO to siplay rpm insted of a 3d axis. On my X3 mill, I use a marine diesel large diameter VDO analog tachometer that I found cheap on eBay - of all that is the best readable solution. Chris
22nd Oct 2010, 04:14 PM #10
Whats the round knob on the control panel for?
The remote head on the VSD is nice. Is the motor rated for that rpm or did you over speed it? I have a VSD on my mill but I haven't been game to over speed it yet(or under speed it for that matter).
22nd Oct 2010, 05:20 PM #11
> Looks great.
> Whats the round knob on the control panel for?
Fully counterclockwise, the spindle stands still. Fully clockwise is maximum speed.
(The arrow knob is stop in the middle, right is forward and left is reverse)
> The remote head on the VSD is nice.
I like it too. This is my first VSD with a removable display unit. It is definitely worth looking out for.
> Is the motor rated for that rpm or did you over speed it?
The motor is the original motor that Hercus installed back in 1988. The brand is "Elektrkovina". That is a factory in Slovenia. When Hercus choose it, Slovenia was still part of communist Yugoslavia. Back then, motors from over there were bargain price but poor quality. Well, it still works today, which in itself is a compliment to the makers, which often had to use substitute materials. And even a bigger compliment, it now works with a VSD.
As for the rating, back in 1988 very very few top brand name motors were VSD rated. This one is definitely not. As for the speed, it is and was common practice for makers of small induction maors, to use the same rotor in 2 and 4 pole motors. A 2-pole motor running directly at maind frequence of 50Hz does about 3,400rpm. The same as this 4-pole motor will do at 100Hz VSD frequency. So it is safe to use at that speed.
Safe is only one thing. Efficient is the other. And motors not VSD rated are never very efficient at frequencies above some 70 or 80Hz. This motor will deliver not much more than 1/8HP at the lathe spindle at 100Hz. In fact, with the bearing preload slightly on the tight side, it cannot even reach 100Hz anymore. Then again, I usually need such speeds only for polishing or turning very small diameters, which does not call for much power anyways.
> I have a VSD on my mill but I haven't been game to over speed it yet(or under speed > it for that matter).
The maximum speed would depend on the spindle and its bearings and the type of lubrication.
Under-speeding is never a problem in home/hobby use, at least not in my experience. In industrial use this is different, because at low speeds the motor fan does not deliver a sufficient airflow for cooling. It it common practice to remove the motor fan, and replace it by a separate box fan that runs at a constant speed, regardless of motor speed. That said, its really only a problem with prolonged running. I never had a hot motor on my other lathe or mill, because I simply do not do any production work on it. I make only one offs, and the time to check and measure gives the motor enough time to stay cool.
22nd Oct 2010, 07:48 PM #12
Do you change speed with the belts and make fine adjustments with the VSD or do you do it all with the VSD?
22nd Oct 2010, 10:27 PM #13
> I guessed speed control but the one on the VSD had me thinking twice.
You got to tell the VSD software which one to use.
I am used to smallish lathes with the controls above the headstock.... I rest my left hand on the headstock and with the fingertips like to control speed and on/off at the same time. That needs a larger knob. Especially when facing a large diameter, I like to increase speed towards the center and decrease towards the edge. Same when turning and chatter develops, turn the speed a little faster or slover until chatter stops for the best surface finish.
> Mine can have remote contols, but the display is fixed. The motor is more of a worry for me its 3Hp 415V 1430rpm. The spindles are run up to 5440rpm on simular machines.
1430rpm is a 4- pole motor. At only 3HP, It is very likely to have the same rotor as a 2 pole motor that spins twice as fast. It should be safe at up to 3,000rpm.
But there is another safety issue to keep in mind: the chuck. Every chuck has a safe maximal speed. Especially cast iron body chucks can contain casting imperfection and cracks. They can explode if spun too fast. Machined steel body chucks have a higher max speed. A typical 6" chuck has a max speed of 3,500-5000rpm, depending on make and price. Collets are usually no problem at very high speeds.
> I'll keep an eyes on the temp. The slowest speed I have is 80rpm so half that would be plenty slow enough.
With variable speed, you need to change the belt position less often (the more you oversize the drive, the less gear changes will be needed). I find that for tasks that need little power, like chamfering or countersinking, I leave the belt at the fastest setting and can throttle down slow enough.
> How efficient would the motors be under speed?
A common, normal, stock, cheap 3 phase motor will barely develop enough power to keep spinning at about 120Hz to 130Hz - meaning 0% efficiency - go any higher and it simply stalls without you applying any load. Meaning it is useful in machining up to some 100Hz. Dedicated (and really very expensive) VSD motors exist and these can go up to 400Hz. But may well cost more than a whole (new) Hercus lathe. A normal cheap 3 phase motor can cover about a 4:1 speed range with a cheap v/Hz type VSD, and about 1:6 to 1:8 speed range with a modern sensorless vector type VSD. Vector VSD's cost typically about 1/3 to 1/2 more than V/Hz VSD's.
>Do you change speed with the belts and make fine adjustments with the VSD or do you do it all with the VSD?
Both. For home/hobby use, one chooses the smallest VSD drive that will do the job, to save cost. That means that one has to keep (and keep using) the gearbox, be this a geared head or in the case of the Hercus the cone pulleys. In industry, it is common practice to oversize the VSD drive, such as to ensure it has the power required at the lowest speed without changing gears.
VSD drives (drive = motor+controller together) are nearly constant torque up to base speed, and nearly constant power above base speed. Base speed being the speed/frequency shown on the motor nameplate, usually 50 or 60Hz.
23rd Oct 2010, 12:04 AM #14
Do you have your VSD set to free run stop or controlled stop?
23rd Oct 2010, 08:36 AM #15
My motor is made by Jih Chin Electric Machinery Co in Taiwan, no idea how good or bad they are.
One hint is the insulation class (of the copper wire used inside for the stator windings). Often that is specified on the nameplate (for example class: F). Higher letter means better insulation able to withstand higher temperatures and voltages.
Since good insulation is expensive, it often goes along with better bearings being used and more careful rotor balancing. With motors, you get what you pay for. But fortunately 3-phase induction motors are the simplest and cheapest type of electric motor there is. So if it breaks, see your local dealer for a brand new motor. I also found that real bargains on new 3-phase motors can be found on eBay.
I have no idea what sort of inverter I have. But 50% over and under should do me fine. I doubt I'll be using to many milling cutters smaller than 1/8".
If it does not say in the nameplate on in the model name or in the manual something like "vector", then it is a V/Hz type. Even the simplest V/Hz type will let you do 50% over and under (that is only a 4:1 ratio).
Do you have your VSD set to free run stop or controlled stop?
I set them all up to use dynamic braking. On a mill or drill you can usually set the braking tome quite short, like 1 or 2 seconds. On a lathe it depends on total inertia:
if you use a light collet chuck you can brake in 1 or 2 seconds, but if you use a large chuck along with a heavy workpiece, the inertia is too large and the bus voltage in the VSD rises too high and the VSD "trips". Tripping meaning it stops braking and lets the motor coast to a halt and displays an error message. You then have to select a longer braking time, say 5 seconds - still faster then letting it coast to a halt.
On a lthe like the Hercus 260 you have two more problems: once the drivetrain itself has a huge inertia all of it own (all cone pulleys and Vee pulleys are made from heavy cast iron). And second it uses a threaded spindle nose, meaning that if braking too brisk the chuck could spin off the spindle and fall on your foot.... That is why all modern lathes do not use threaded spindles anymore.
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