The Saga that is my Conquest mini-lathe re-furb.

Well as documented else where on this forum I tackled the sloppy Tailstock problem and started adding the Tailstock DRO (the barrel markings were very faint and Imperial only ) the DRO is both metric & Imperial at the press of a button.

The next stage was to modify the "control box" with speed controller and dodgy switching from forward to reverse (the switching mod is detail elsewhere on the forum). I should explain the original OEM speed controls had been replaced by the previous owner with another chinese self contained speed box which he had fitted side ways so that for me setting speed was too close to the chuck for comfort.

I re-arranged the layout in a totally enclosed box (shown in another thread) to keep swarf out of the electrics after hearing horror stories of long strands of excess metal infiltrating the electrics letting out the vital blue smoke that keeps electrons flowing :-)

Having tried my new layout it worked but the newly added Tacho was now awkward to read.

ORIGINAL DESIGN:-

Attachment 19848,


Time to redesign! I bought a second set of parts :- control box , Thump switch (emergency lock out ) Toggle switches, Tacho panel, Fans , 240Vac to 12VDC wall wart and chinese speed controller.

The first thing was to strip the P.C. board from the wall wart (power for the tacho & fans ) & did the same to the new chinese speed controller. the idea being that the control pot & on/off switch with their Bezel/face plate can be mounted remotely from the PCB allowing greater flexibility to the layout within the box.

Attachment 19845,

The LH lower cct board is the "wall wart" innards and the RH cct board is the Chinese speed controller

The speed controler board has a huge heat sink on it and since it now sat in a far larger but fully sealed case, I added two 40mm fans one mounted directly under the heat sink (when the box is mounted vertically on the lathe ) in the base of the box sucking cool air in, the second fan is almost on the top of the right hand side blows the warm air out.

Having done all that I am now far happier with the layout. (PHOTO'S to Follow ):-

Attachment 19844,

RH side exhaust fan

Attachment 19846,

Front facia layout (also shows the lower inlet fan filter in place )

Attachment 19847

LH side mains input for "kettle lead "

the next major job was to replace the head stock bearings for tapered ones (the original are plain ball bearings ) whilst i was at it I decided on checking the plastic gears inside. NOT IMPRESSED so i ordered the cast steel versions at the same time as I ordered the bearings.

I had better point out at this point I never undertake anything I am not well read up on when it comes to spending money, so i read everything and watched endless videos on converting mini-lathes. and in particular bearing replacement & head stock "stuff".

So all the bits are in and i started work and being super cautious I went to a Pals workshop for the day to do this "just in case ".

Now the plastic spindle gears are all one part with a a 40mm long key & keyway. Now the metal gears come in THREE parts two gears and a spacer which when put together as a stack on a face plate are with 5 thou of the plastic one piece in overall length. So far so good.

However when you assemble said three pieces on the spindle the key is not long enough to drive the last gear ! it is TOO SHORT by 10mm at least.

After much use of quite a few Anglo Saxon invectives my pal and i decided to lengthen the original keyway by 12mm however neither of us had any 5mm key material available . So I cut the original key in half (reasoning that since the spacer between the two gears takes no force it needs no direct drive power only to stay in place and not chafe against the two gears by having it "idle".

The two keys are now kept apart by a 4mm silver steel rod so they stay put & drive the spindle thro the gears as intended.

An exciting day! What i cannot understand is that NONE of my reading has highlighted this MAJOR design flaw in the 3 piece gear conversion kit.

OR is it that with my luck my spindle was a friday afternoon spindle that did not have the proper length cut keyway in the first place ?


Thoughts......................................



QUESTION:- I have inherited a 3 PHASE 240v DC MOTOR need a control circuit for it ? loads of guff on 3 PHASE AC motors none on DC pointers PLEASE ........................TIA

Y-geo,

Very nice modifications and information. I have considered doing the head stock bearing replacements for tapered ones but I already replaced the plastic gears inside and not looking forward to taking the headstock off the ways again. I already used the Rollie's Dad's Method of Lathe Alignment using steel shims (MiniLathe Alignment) to perfectly align the 7"X14" lathe headstock which led to redoing the tailstock alignment and height. I bought the little lathe in 1993 and it has been an okay metal lathe. Doing the alignment is lot of trail and error work, dependent upon the torque of the headstock bolts, and I rather not go through the alignment again because my main lathe is an extremely precise 12"X37" gear-head, gap bed lathe. The 7"X14" lathe is now relegated to secondary operations and fitted for using ER32 collets and can also use a small chuck for tiny parts ( http://www.homemadetools.net/forum/t...0983#post58534 ).

I am looking forward to seeing more of you lathe modifications.

Paul

Paul,
thank you, and thanks for that link on alignment, put that aside for when it is all "done" and ready to be put into service.

When you did the bearing change did you stick with the original plastic gear assembly ?

Quote:

---

Originally Posted by Y-geo

QUESTION:- I have inherited a 3 PHASE 240v DC MOTOR need a control circuit for it ? loads of guff on 3 PHASE AC motors none on DC pointers PLEASE ........................TIA

---

If it is a DC motor, and the name plate indicates this as well 3 phase, this would be an electronically commutated motor. This requires a special controller.
Do a google search for "3 phase dc motor controller schematic diagram". As well "BLDC" = 'brush less DC'.
Finding a 240V controller may be difficult. My quick search found many on eBay but all were low voltage i.e.<50V.

Steve

Steve,
Thanks, been doing a lot of that BUT it seems AC 3 phase is very well covered but DC 3 phase is non-existent except as you say for sub 50 volts.

Although I gather that treadmills run at 80 V but again i can find no new cct for those only cannibalize ones and most of the electronic /technical info is at best "patchy" and not really enough to start a controller from scratch.

I may have to buy a "toy" controller with the biggest ratings available and reverse engineer it with higher voltage/wattage (if those exist ) semi-conductors etc


The motor in question is :-MOTION CONTROL PRODUCTS LTD.
PART NUMBER:- M57BLR95-220-4200AL-1

220V 4200RPM

The company were VERY unhelpful except to tell me the motor was now obsolete and refused to furnish any tech spec/use/ control info except that it is 3 phase (and that was after I said i was puzzled by the fact that it had 3 wires instead of two for the usual DC motor. Which left me a bit puzzled as 3 phase AC usually has 4 wires if my creaking brain is remembering right.

Attachment 19858

as you see its' body is just about 4" /100mm long

may be as one of our members says that "all of us are smarter than just one of us " and someone here knows some thing about these beasties?


PS STEVE just banged up a copy & paste of your suggested phrase and i found some leads, My Google Fu it seems is not upto par of late Thank You.

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Thanks Y-geo! We've added your Mini Lathe Controller Redesign to our Electrical category,
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<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-mini-lathe-controller-redesign"> <img src="/uploads/204996/homemade-mini-lathe-controller-redesign.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-mini-lathe-controller-redesign">Mini Lathe Controller Redesign</a> <span> by <a href="http://www.homemadetools.net/builder/Y-geo">Y-geo</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/lathe'>lathe</a>, <a href='http://www.homemadetools.net/tag/controller'>controller</a> </div> </div> </div> </div>
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Y-Geo,

I replaced my plastic headstock gears with metal gears. There are many pros and cons on using the plastic vs. the metal gears. The plastic gears may have less running noise and could shear off if you crash the lathe but in my last 24 years of using my mini lathe have have never crashed lathe and now satisfied with using the metal gears. I did not notice much of a difference in the sound levels using plastic vs. metal and it may depend on the lubrication. I use a high pressure gear grease in the mini lathe headstock with the product "Dart LUBE CMD Extreme Pressure Lubricant" (see https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 ) and it seems to make the gears run with little noise. Also see the discussion at http://www.homemadetools.net/forum/r...ad-lathe-16967 .

Good luck with your mini lathe improvements. I think it is a very worthwhile endeavor and can see the difference in the higher quality machined parts.

Regards,

Paul Jones

Quote:

---

Originally Posted by Y-geo

Steve,
Thanks, been doing a lot of that BUT it seems AC 3 phase is very well covered but DC 3 phase is non-existent except as you say for sub 50 volts.

Although I gather that treadmills run at 80 V but again i can find no new cct for those only cannibalize ones and most of the electronic /technical info is at best "patchy" and not really enough to start a controller from scratch.

I may have to buy a "toy" controller with the biggest ratings available and reverse engineer it with higher voltage/wattage (if those exist ) semi-conductors etc


The motor in question is :-MOTION CONTROL PRODUCTS LTD.
PART NUMBER:- M57BLR95-220-4200AL-1

220V 4200RPM

The company were VERY unhelpful except to tell me the motor was now obsolete and refused to furnish any tech spec/use/ control info except that it is 3 phase (and that was after I said i was puzzled by the fact that it had 3 wires instead of two for the usual DC motor. Which left me a bit puzzled as 3 phase AC usually has 4 wires if my creaking brain is remembering right.

Attachment 19858

as you see its' body is just about 4" /100mm long

may be as one of our members says that "all of us are smarter than just one of us " and someone here knows some thing about these beasties?


PS STEVE just banged up a copy & paste of your suggested phrase and i found some leads, My Google Fu it seems is not upto par of late Thank You.

---

Y-Geo，

the motor is a 57mm 3 phase Brushless Motor，If there are only three lines, he is not a Hall element version.the
the M57BLR95-220-4200AL-1 Is the old number，According to the new naming rules, it is 57BS95R-##-2242-T-S,the##is watt
sorry I did not find the data for this model, I think it is custom product for mini lathe，
If his label is correct, you can use the No Hall 310v300-500w Universal Brushless Motor Controller, but there is a high risk. At the same time the cost will increase。your chinese speed controller is a Brush motor controller ，can not be used with this motor！
My advice is to temporarily give up this motor, with a conventional DC motor.
good luck(I am very poor in English, the above content from Google translation, may not be accurate)

Very nice mods. Thanks for posting.
Mike

Paul,
Your headstock internal metal gears were one piece or 3 pieces?

Did you stumble on the same problem that the keyway/key was too short ?

The fact i can find NO mention of this flaw has me puzzled
Thanks

Mike,
I, and my family, are a bit gobsmacked that this bit of "dad being his usual "I can do better " (quote from the youngest brat ) has become some thing of a hit.

I will continue to post what I do and find as GOTCHAS so that others avoid my mistakes :-)

thank you all for the recognition nice that others can enjoy this mans work.

Make Everything,
That was very helpful Thank You. I assume from what you say that if there were 5 wires it would have hall effect circuit built in.

the british importer did say it was an obsolete motor (which they neglected to mention when i bought it, but at the price i paid not overly fussed ) I will stick with my set up as i have now and continue to research for that motor as i want to use it on a mill or drill.

As for your english I can tell you it is far better that my Mandarin or Cantonese which my first wife tried to teach me. I like your knot tying skills some of which i did manage to learn from her all those years ago.

"No Hall 310v 300-500w Universal Brushless Motor Controller" i did a quick google but came up empty do you have a lead on such an item please?

Although I know how it works,But I can not build it, he is more than my knowledge and ability，The motor is the same as the computer's hard drive motor， in Industrial products, usually using arm cpu control。
I think maybe you can buy a 50v BLDC driver, check the windings, try it can work at low voltage, or make low voltage winding for it ,Brushless motor winding is very simple, you can refer to some brushless motor design method, you only need some enameled wire and calculation

Make Everything,
thank you, still busy googling to find a suitable circuit or commercial unit for my needs. Luckily i am not in any hurry :-)

it seems that the control IC's are all low voltage but can act as controls for high power MOSFETS that actually power the motor, so i live in hope
thanks for your support