Newbie needs advice about a lathe

[abby]

Thanks for the replies , my post was a bit tongue in cheek!
I was thinking of an outdoor boiler using the wood from some trees we cut down last summer, connecting a useable heat output to my existing indoor radiators is the problem to solve as the hot water would need to travel quite some distance.
An hours melting session leaves the workshop comfortably warm for about 8 hours , thats burning propane.
I can burn diesel (farm fuel) but it does smoke badly until the furnace is hot and waste engine oil is definately not allowed in the UK.
I have neighbours close by so have to keep my operation lowkey.
Dan.

 

[clockworkcheval]

Heating with wood holds my close interest. From age 50 thru 70 I hauled an annual 15-20 tons of oak out of the surrounding woods to feed my large wood/waterstove. The heated water from the waterjacket fed into the floor heating system of my 25 x 100 feet converted farmhouse. The measured wood-to-heat efficiency was about 75-80%. My wife found the beast so ugly that I had to alternate it every summer/winter-season with an ornamental open fire. When burning this actually brought the temperature of the house down. Seven years ago I moved to a high-tech Austrian wood pellet heating system with a measured efficiency of 95-98%. The logistics of fuel handling are now reduced to a truck which blows twice a year a load of wood pellets into a converted farm-container on the grounds. Back to machinetools: in my workshop I'm installing a much smaller wood/waterstove which heats the water through a spiral above the fire. The heated water feeds into the floor heating of my 12 x 30 feet workshop. The stove eats only 2-3 tons dry oak per year, which this old man can handle. And this floor heating means that my machinetools don't worry any longer about rust and require only a couple of hours early in the morning to reach full operating temperature for precision work. See attached pictures.

 

[WisJim]

I grew up with wood heat and our homes (until the last year) have had wood heat. Insulation of the building reduces the amount of wood required and is one reason I was able to keep using wood heat into my 70s--that and lightweight electric chainsaws meant that both I and my wife could cut up the firewood. The last few years, though, before moving to town, we added minisplit heat pumps to our heating system at the farm.
Back to the electric blanket question--we preheated our beds with an electric hair dryer. It took a minute or so per bed and meant that we crawled into a nice warm bed instead of between cold sheets. Our body heat kept us comfortable as long as we used the right weight of quilt or blanket. And flannel sheets make a big difference too.

 

[Steamchick]

Thanks for that info I had assumed wrongly of course that the speed knob controlled the power to the motor but obviously not, the problem is that every time you stop it you then have to faff with the covered locked ON OFF switch to get it going again and if you use the forward stop reverse switch the same thing happens there seems to be no simple start stop with it at all

Hi Old Guy,
Please may I comment without causing offence? As another "old guy" (Yeah, I have the T-shirt...) I appreciate where you are coming from with the complexities of "modern" switches.
I have a lathe from Chesters, so understand where you are coming from.
But the BOTTOM LINE is simple.
The switches are dome the way they are for SAFETY. I didn't write the rules, but whoever did only thought of SAFETY (Not convenience!). Us "Old Guys" survived by learning to do things in a safe manner, so we didn't need to be molly-coddled by "new fangled systems that make things "safer" for the numb-nuts who may not have a clue about what wrongly operated machines can do to mangle, hurt and destroy human flesh.... But The world now isn't built the way we knew it ... and now everyone is bound by legislation they don't even know about. e.g. you can be prosecuted for having a gun without a licence, but when you get a licence there is nothing to stop you from doing nasty things with it. But if you buy a machine tool (e.g. the lathe) it MUST come fitted with a "logical" set of controls, to protect you from turning it ON and nadgering yourself... and if you disable any of the built-in Safety bits, and something goes wrong, the "insurance company" won't pay-out. (In industry you can be prosecuted and sent to jail for disabling ANY Safety controls).
So to put it simply:
I have had to learn to use the "complicated" Safety ON-OFF buttons to start and stop my lathe. (I may be stubborn and I am NOT too old to learn and change!). The speed controller knob is just that. Set the speed for the right speed for the cut and don't fiddle with it. Only change it when you change the radius of cut, or material, or whatever, and not while cutting is in progress. The electronics are not built to do that much, and are expensive to replace WHEN you manage blow them up.
You SHOULD only change the FWD-REV switch when the motor is stopped. It would blow the controller (at £120 each) if it wasn't set to instantly knock off the power if you switch from FWD-REV or t'other way. It is not built for dynamic braking or rapid changes. ALWAYS hit the STOP to stop the lathe before you switch ANYTHING, or stick hands or other bodily appendages near the rotating bits. ONLY change speed when NOT CUTTING. Set the correct speed before you engage any cut, or other tool. The controller will automatically alter the current to maintain the constant speed when the cut is applied, within the laws of physics, and electronic bits.
If you don't like SAFETY controls fitted to modern machines, then I am sorry for you. As we get older we do get more reluctant to change, and equally lose control of some of our bits, (eyesight, etc.) and do not accept that our brains are naturally much slower than when we were 21.... But the "big organisations" (Governments, Insurance people, legislators, etc.) have done the studies and recognise human limitations so try to help us stay safe. And we Old Guys have bred the people who have made the decisions.... Even "spell check" doesn't spell things like my 1960s dictionary!
One other small thing.... Please tell me the model of lathe, if it is like mine I can tell you a few things that are not in the "destruction manual"...
Cheers, young man,
K2

 

[Steamchick]

Hi Old Guy,
Seems I picked-up this thread 5 pages back, or something?
I see now (after getting the "more recent posts"!) that it is a DB10 lathe. The controls look like my DB8VS (VS means variable speed!). The smaller lathes use a 0.75kw or 1kW Permanent magnet brush motor. The speed controller sets a DC voltage (after rectification from the 240V AC mains), and then varies the current to maintain the speed constant with varying load using SCRs (Thyristors to Old Guys!). The SCRs are "electronically fragile" and expensive to fix. A replacement control board on the web would have cost me around £100 a few years ago, after the smoke escaped from the electronic bits. I found the root cause was flash-over shorting things out inside the motor, at the brush holder. EASY to clean, and I do it regularly now. The carbon dust from the brushes covers all the insulation, forming conductive tracks, so when the SCRs turn up the volts to maintain the speed as a cut comes on, the motor shorts to earth while the carbon is vapourised to clear the short... or the fuse blows, or the SCRs burn-out.... There is some sort of Inductive reaction when the flash-over short occurs, a bit like spark ignition, the magnetic energy in the motor can cause a high voltage spike that blows the SCRs. Once one blows, the mains voltage passes through the SCR and just fries everything else until the fuse blows.
So periodically, (Immediately if you hear a "phut" or "bang" from the motor!) SWITCH OFF and disconnect the mains, remove the end cover, the 4 hex socket screws to release the motor carrying plate, slide the motor out and disconnect the wires (noting where they fitted!). Strip the motor brush-holder and clean thoroughly with alcohol (or car Brake cleaner?) but DO NOT BREATH THE CARBON DUST. Re-build and you should be OK for a couple of dozen more hours of fun. But if it is a brushless motor you will have loads of fun without "brush dust" problems.
Incidentally, please use the guard when operating the machine. It is there to protect you during cutting. I knew a guy who had been blinded after a tiny chip of metallic swarf entered his eye from a cut (no guard, no eye protection) and within a year the eye stopped working. He said he could see the metal bit as a black dot in his vision and it moved around inside the eye. It moved when he held a magnet close to the eyeball. The "red dot" on his eye had healed over, so he didn't think he had a problem... Then 2 years after that the other eye stopped as well. He was a blind adult at 23...
Please think of YOUR SAFETY.
K2

 

[Steamchick]

Old Guy.
Did you get the wiring diagram? (I've not searched all 9 pages of gardening stuff, etc. to find all the lathe stuff...).
Here's a copy, attached below:

And the link to the Chesters page so you can download the manual. It looks like it has the same motor as mine.
https://www.chesterhobbystore.com/shop/metalworking-machines/lathes/db10vs-super-lathe/

 

[Old Guy]

Hello Steamchick

No offence taken thank you for all your safety advice which I will take on board and try to use the lathe correctly and safely.
I do have the manual for the machine and it does have a wiring diagram though I will be hoping I don't need to use it.
I would hope that the motor is of the brushless variety but there is nothing in the manual to say what it is and I shall not be delving into the lathe at this point to find out. Think I will look on the Chester web site and see if it says what type of motor it is in their blurb.
So far I have done very little on the lathe mainly due to difficulty in obtaining metal stock to the dimensions I want and at affordable prices, and also getting the tooling needed to perform the tasks I would like to try

Thanks for your help and sorry about this type face that it has decided to use I will have to sort this out
John

 

[Old Guy]

I have just been on the Chester web site and can't find what kind of motor it is but it looks like this model now comes with a 1200W motor instead of the 750W in mine

 

[BaronJ]

Hi Guys,

All the DC Permag motors that I've seen suffer from one major problem, HEAT ! Even BLDC ones, though they are much better at protecting themselves.

Unlike a normal AC single or three phase motor where the field windings are mechanically and thermally connected to the external case, where any heat can escape easily, a Permag motor can only get rid of the heat through conduction through the bearings at the ends of the armature. This makes these motors difficult to cool and easy to burn out. Using and external fan helps but the motor has to be stationary to take advantage of one, the internal fan, if it has one, is little more than useless. The spinning armature pushes the air away from the armature preventing efficient cooling.

I now monitor the armature temperature to prevent the armature getting above 40 degrees C, which is the rated maximum temperature for my motor !

 

[Steamchick]

Thanks for the advice Baron. Just a point on my experience. Motor Brush dust after a few years of use has been the root cause of my most expensive on-going costs. I.E. the blown SCRs. Although I have done a lot of slower speed cutting, and without gearing the torque drop-off with the 750W motor is really significant, I have never had an overheating issue. No sign or smell from hot windings when I have had the motor apart.
My Cautionary Notes to all with these lathes is simple. Regular motor cleaning can save you from > £120 of costs replacing blown electronics. These cheap Chinese lathes are made to design standards that are much closer to the limits than some would think "normal" in the West.
The ON-OFF SAFETY BUTTON failed first. I guess because it is used at every start and stop of the mainshaft. (About 8 Years use, but I am not a heavy user of the lathe, more like "casual" = 1 model per 5 years?.). Then I started getting odd sputtering noises when starting heavy cuts at moderate speeds (10 years). (I now know this was flash -over in the motor from carbon brush dust).
Then I experienced a frightening few bangs when I turned it to high speed one day. Followed by a bang-flash as it blew the SCRs. Also, an in-line filter choke blew (a track on a PCB had vaporised!). And I replaced that for a proprietary unit. I have replaced the brush holder in the motor (burned by flash-over).
I have fitted an auxiliary fan that runs permanently when the lathe is powered-up, that blows through the motor. The 5W fan from the web is titled for a computer printer.
And I strip and clean the motor brush holder when I clean the lathe when it gets an annual check, lube and adjust.
I also fitted a vent on the plate at the back of the electronics box which helps cool the electronics considerably.
I have replaced the fuse holder that melted one time when it blew a fuse.
A cheap lathe like this is not meant for frequent high use without major and frequent maintenance.
The fuse should be wired on the LIVE entering the lathe, not the neutral, but some Chinese machines install it on the Neutral. This can leave the whole lathe LIVE, after a fuse has blown, and you can get a nasty shock from a 240V LIVE lathe!
Get your certified electrician to re-wire safely if you have that issue. The household fuses etc. Cannot protect you from that electric shock. (Been there and done it!). Rubber soled shoes and dry wooden floors reduce the "belt" but it is still shocking.
Finally, keep the motor CLEAN (inside) from carbon dust at the brush holder.
For durability failures, I have noted that the cast iron lathe main casting are not the strongest, nor the fixings, and even using torque control standards for Western materials I have suffered stripped and worn threads. So treat it gently when tightening everything. Torque for a 20 ton steel, I.E. half of Western mild steel torques.
And when cutting larger sizes, respect the slower speed of rotation, and keep the cuts small, and feed rates suited to the rotational speed, to preserve your valuable motor and electronics from overheating.
Old Guy John,
Please ask via this thread when you have any questions and we will answer as well as we can. Including material sources if you have a problem?
Regards,
K2

 

[Old Guy]

Here's a little question I am hoping to get a medium sized milling machine (single phase) and was wondering what is best belt drive or direct drive, when I say medium I mean not in the £700 to £800 range more in the £1000 to £2000 range and hopefully with brushless motor your advice much appreciated

John

 

[Steamchick]

I have a drill- mill that is 30 years old, based on a pedestal drill with milling table beneath. Embarrassing when the head rotates around the column when milling. It ruins the job! But the 1.5 HP single phase AC motor with 6 speeds via belts and pulleys ensure loads of torque for larger diameter tooling, at lower speeds, yet still has more than enough torque for top speed small tools.
Modern Chesters Champion 20VS Mill is as good at top speed, but is limited on tool diameter due to the torque drop-off via the variable speed drive at lower speeds. I guess it contains nylon gears that are cheap and fail from time to time. (As do my Mate's gears on his similar mill. He keeps a set of spares on the shelf!).. But the modern one is a step more precise than my worn-out mill-drill. I would not waste money on a smaller machine.
K2

 

[Steamchick]

Hi John,
Just been browsing the interweb, for my Mill-Drill info.
But instead found these motors, that are basically the same as used in the Chesters lathe I have, and think you may have too?
https://www.ebay.co.uk/sch/i.html?_...6.m570.l1311&_nkw=treadmill+motor+dc&_sacat=0
FYI My Mill-Drill is an equivalent to the ZX15 attached. Takes a 25mm / 1 " milling cutter, or 2 1/2" radial cutter. max.
K2

 

[BaronJ]

Here's a little question I am hoping to get a medium sized milling machine (single phase) and was wondering what is best belt drive or direct drive, when I say medium I mean not in the £700 to £800 range more in the £1000 to £2000 range and hopefully with brushless motor your advice much appreciated

John

Hi John,

Knowing what I know now, there is no way I would have bought a machine with a brushed DC permag motor ! (Brushless BLDC) motors are definitely better than brushed ones, however a good old single or three phase motor would have been preferable.

A mini Bridgeport machine would have been Ideal. I don't have the headroom for a full size one.

For what its worth, I've just replaced the DC permag motor on my mill with an adapted treadmill permag motor. As far as plastic gears go I replaced all the gears in my mill with steel ones ! Actually cheaper than a replacement set of plastic gears. Picture below.

 

[Steamchick]

Hi Baron J.
re :"I now monitor the armature temperature to prevent the armature getting above 40 degrees C, which is the rated maximum temperature for my motor !".
The note on the motor: "40deg.C." is the max that the motor should be surrounded by so it should not overheat. I'm not sure where you are in Yorkshire if your workshop ever gets that hot, but maybe if the vents to the motor compartment were restricted that could happen. Anyway, the armature may get hotter then that safely... but not hotter than 80C in the core of the armature windings, by my guess! Where are you monitoring temperature? At the outlet from the airflow through the motor? - or the inlet? I am interested in doing something similar - but also to the (Previously closed) electronics chamber.
Thanks,
K2

 

[Steamchick]

Hi (Again) Baron, What is the change in motor between the original "DC permag motor on my mill with an adapted treadmill permag motor."? Is it just the bigger fan? That extra cooling is probably part of the "HOW" that they get the higher motor power rating. But it would have to be combined with some cleverer armature windings (bigger wire for higher current?), closer clearance to the magnets, better magnets, or something? - Or is it a bigger bodied motor? I don't think it would fit my lathe with the big fan attached. Would you mind giving some overview of the motor's dimensions? - including fan? - Reasoning: a bigger rated motor may stay cooler than the current motor at the same load. BUT the risk is that higher available torque may overload the current rating of the variable speed, if the extra 25% is utilised, or the motor's duty cycle would be increased and result in the variable speed control overheating, or the available torque would simply enable heavier cuts that twist the bed of the lathe (I have been there before!)... etc.
Ta,
K2

 

[ajoeiam]

Hi John,

snip

A mini Bridgeport machine would have been Ideal. I don't have the headroom for a full size one.

snip

Greetings

Some of the other brands of smaller mills are sometimes findable with an apug (horizontal to vertical) head.
I've got one here that is only some circa 60" tall.
(Now it doesn't have speeds to 4k+ rpm either but its quite a usable tool.

 

[BaronJ]

Hi Baron J.
re :"I now monitor the armature temperature to prevent the armature getting above 40 degrees C, which is the rated maximum temperature for my motor !".
The note on the motor: "40deg.C." is the max that the motor should be surrounded by so it should not overheat. I'm not sure where you are in Yorkshire if your workshop ever gets that hot, but maybe if the vents to the motor compartment were restricted that could happen. Anyway, the armature may get hotter than that safely... but not hotter than 80C in the core of the armature windings, by my guess! Where are you monitoring temperature? At the outlet from the airflow through the motor? - or the inlet? I am interested in doing something similar - but also to the (Previously closed) electronics chamber.
Thanks,
K2

Hi K2, Sorry I don't remember your name !

Whilst the original motor had an internal cooling fan and top and bottom air vents, the replacement treadmill motor that I have modified and converted to replace the original 750 Watt motor doesn't have any air vents as such, its almost totally enclosed. However since the heat is lost through the bearings, a thermistor probe in an oil bath hole drilled into the top of the shaft is used to monitor the temperature.

At the moment temperature monitoring is experimental and determined by usage. I can check the external body temperature with either an infra red temperature sensor or the thermistor one. Which will give me a temperature differential. The workshop temperature rarely goes below 50F or above 70F.

 

[BaronJ]

Greetings

Some of the other brands of smaller mills are sometimes findable with an apug (horizontal to vertical) head.
I've got one here that is only some circa 60" tall.
(Now it doesn't have speeds to 4k+ rpm either but its quite a usable tool.

Hi Joe,

At my age its a bit too late to bother, which is the reason for the motor repair. My children say it will all go in the skip when I fall off my perch !

 

[BaronJ]

Hi (Again) Baron, What is the change in motor between the original "DC permag motor on my mill with an adapted treadmill permag motor."? Is it just the bigger fan? That extra cooling is probably part of the "HOW" that they get the higher motor power rating. But it would have to be combined with some cleverer armature windings (bigger wire for higher current?), closer clearance to the magnets, better magnets, or something? - Or is it a bigger bodied motor? I don't think it would fit my lathe with the big fan attached. Would you mind giving some overview of the motor's dimensions? - including fan? - Reasoning: a bigger rated motor may stay cooler than the current motor at the same load. BUT the risk is that higher available torque may overload the current rating of the variable speed, if the extra 25% is utilised, or the motor's duty cycle would be increased and result in the variable speed control overheating, or the available torque would simply enable heavier cuts that twist the bed of the lathe (I have been there before!)... etc.
Ta,
K2

Hi K2,

The replacement motor is 75mm diameter compared to the 55mm diameter of the old motor, however it is 60 mm longer and the armature body is 20mm greater in diameter. The main issue with adapting the treadmill motor to fit was the 17mm shaft diameter compared to the 10mm shaft diameter of the original one. This treadmill motor is far more substantial than the original. Power wise the motor is capable of twice the power of the old motor. I did measure the mains input power with the new motor running at full speed off load and it is very little different from what I measured on the old one. I do need to check it under load though.