Coil winder

[Timber_MG]

Ampdog had a problem with transformer coil winders in having valve output transformers wound, so I thought why not adapt my cnc-router's Z axis to wind some transformers and perhaps wind myself some OPT iron while I am at it. I still had an old controller and steppers and will see how well they work in this project.

I don't have much in terms of images to show at the moment, but I've sent a 25mm aluminium plate to the machinists to machine a bearing mount for a dual row angular contact bearing with an ID of 20mm. The bobbin is to simply screw onto an M20 bolt and be fastened with an M6 cap screw. Unfortunately M20 taps are expensive for only using them a few times, so I'll rather jippo a bolt to cut some thread into the wooden formers.

I will drive the spindle with a timing pulley (2:1 drive ratio) attached to the back of the bolt and set up my cnc software to use the new rotational axis with a simple "linear" unit of 1 per rotation.

This will result in a winding program that would look like the following:

G1 X50 Y200 F5 for 200 windings over 50mm (0.25mm wire diameter) at a rate of 300 rpm (5 rev per second). The machine control software ramps the speed towards the start and end of the command. I wonder whether if I attach my 300W AC servos if the winder would wind at 1500 rpm (or a 200 count winding row in 8 seconds + a little for the speed ramping).

By adding a microswitch to one of the inputs (or using a keyboard) one can step through the program externally to allow the operator a prompt to place the insulation layer over the windings.

The odd thing about this winder is that the wire tensioning jig is stationary and that the bobbin moves in front of it.

I'll post some pictures of the build as it transpires. Any input would be most welcome.

[JimGore]

why not adapt my cnc-router's Z axis

You mean the box full of parts you have for building a cnc router? Just messing with you 

Sounds like a fun project. Good luck!

Ian

[Timber_MG]

You mean the box full of parts you have for building a cnc router?

Note the vintage of this item from the hall of f....ame: http://www.youtube.com/watch?v=3vp7CgpnOWo The current setup runs off AC servos, but for the winding I'm reverting to that stepper and controller I collected from you on Sunday. I'll retrofit the motor and parts to a winder in time.

Unfortunately this one will be ferromagnetic and not allow to measure coils on the winder.

Perhaps have a look next time you're around.

Martin

[Timber_MG]

So this weekend went a little otherwise than planned.The machinist where I droppped the parts off hasn't phoned me yet, so I decided to machine what I could. I found on facing the bolt for the jig, that my lathe was a little out of square when taking mild-heavy cuts. Upon closer inspection the lathe has reached the point where I need to re-assemble it as I've been dreading. I really cannot complain for what I got though.

Adjusting a lathe properly requires some metrology insight and equipment. I have the finger dial gauge, surface plate substitute (ground 40mm steel) and assorted items and am quite piqued by how good the guides of this chinese BV20 lathe will be. I pray that the spindle is reasonably well aligned with the lathe ways.

I managed after looking around for a long time to get hold of citric acid and stripped the slide table, cross slide and compound. I also had a very serious altercation with an M2 drill arbor that had gotten stuck that was solved by taking it to a gas flame before twisting with a boobejan spanner. The cleaning of all the small parts took me to after 11 this evening and I'll see whether I can get the lathe assembled tomorrow again to just drill the hole in the bolt.

I have playing with my machine toys all day, nuked chemicals in the microwave (all safe enjoyed lunch and dinner withouth having to cook or clean and am still a married man ;-)

Life is good

[Timber_MG]

My lathe is up and running again, all the parts cleaned, oiled and re-assembled Moves smoothly over most of the bed.

Todo:

Take a fine arkansas stone to my lathe bed in some places

Sort out the alignment issue ... the tail stock is proving a little difficult to align to the bed /spingle properly. I am not yet sure whether it's the spindle or the tailstock (holding thumbs for the tailstock as the spindle is much more difficult to align) Once my bed and tailstock slide is clean of any small bumps left by wear and tear from its past life I'll have to measure quite carefully using various referencing techniques to establish what's really going on.

I am quite enjoying this re-build. Here an image of me clocking up the tailstock. Hard to see, but the clock is held with a magnetic clamp to the spindle and the tailstock is measured at various angles  of the spindle (I was centering the tailstock here)



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[JimGore]

Headstock and tailstock are aligned quite easily if you have 2 pieces of machined roundbar sharpened to a needle point. I used brass to make mine.

Clamp one into the chuck, and the other into a drill chuck in the tailstock. The needle points should line up if everything is set correctly.

To check for parallel, mount a 25mm diameter alu rod into the lathe chuck. Cut the edge true and square. Next, drill a 6mm hole through the rod. It the entrance and exit hole is dead centre, then your setup work is done 

Ian.

[VALVAGLO]

I thought I was the only one who found old but good equipment and then set about trying to restore it to it's erstwhile condition.
I recently acquired an old metal lathe and spent this past weekend doing the oilstone ,polishing realigning etc on it and it also came up beatifully. I must now modify the motor mounting and drive belt system and I will also be ready to do some "turning"

[Timber_MG]

Thanks guys.

@Valvaglo: unfortunately this isn't a classic Myford or something but a chinese BV20 that needs some TLC (and perhaps even some angle grinder). It served the previous owner well making model ship masts, cannons and small fittings.

@ Ian: cutting the stock OD will give me the maximum horizontal alignment error of the spindle to the ways if I mic up the diameters over some distance of cut. I'll definitely give that a go.

I'll clean out the bed first before I do too many changes. There is also some beginning surface rust from a water leak that sprung up in storage to take care of towards the end of the bed where the lathe hardly saw any use.

Once the slide table is bedded properly and the ways don't have any nicks I'll be in a much better position to measure exactly what's going on. At the moment the tailstock is about 0.6 mm high at it's most common drilling poistion and the axial mis-alignment is around 2:100 which is completely unusable for drilling, I'd like to get that to 1:1000 or better.

Becasue I am not sure where the error is coming from, I'll measure as much as I can and use that to guide my actions. My current guess is that I have to scrape the tailstock into alignment but even the tailstock internal morse taper is suspect to scrutiny here. If the error persists on such a magnitude after cleaning the mating surfaces of the tailstock I'll have to look at grinding and/or scraping this thing or replace the headstock with something else.

[Timber_MG]

Ardendorffs don't have spares for this lathe atm, so I'll probably have to shim the toolpost into submission or mill a different slide for it to mount to.

Back the the original topic: The machinist just phoned to inform me that the bearing recesses for the bearings have been machined and are ready for collection. A bit of machine time is less than buying a boring head for my mill.

[JimGore]

I have a boring head which I use on my lathe tailstock.  It is actually made for a mill, but just changed out the arbor to a MT3 and Bob's your uncle.

Rather an expensive bit of equipment, but when you need it this thing is invaluable.  Very nice micrometer adjustment means you can make nearly any size hole larger than around 15mm diameter.

Toolquip and Allied is your friend!  I have the printed catalogue which is simply evil!!!

Ian.

[Timber_MG]

There comes a point where I evaluate how often I use a piece of equipment and the cost of just having a part machined. I have oohed and ahhed a boring head a few times, but I don't do many critical bearing fit operations and give those to a machinist in stead.

That catalogue is not safe for work Pure smut.

[JimGore]

Sure, but have it done by someone 3 or 4 times, then you could just as well have purchased it yourself. 
It is exactly the same thing as the renting vs buying a house argument.

One of my favourites: "A man without tools is like a fish without a bicycle." 

Ian.

[VALVAGLO]

That sounds like me. Now where did I leave my bicycle?

[Timber_MG]

The bearing pockets have been machined and now fit snugly to the bearings. There bearings are double row angular contact types so I don't need to have a shaft running to another bearing. I don't think the winder will apply upwards of 10.000N force

Now I just need to drill and thread the bolt and jig up an assembly to mount the steppers and then I can move onto the steppers. I guess a quick MDF mockup is called for to get this thing running.

Anyone in Pretoria want to offer 5 minutes time on a lathe with a true tail stock and bore two bolts and two pulleys?



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[Timber_MG]

I have been caught up with too many things that have nothing to do with audio this weekend, but I did get to clean up my tailstock slide and measureed the error on my tailstock to about 0.5mm in 100mm (A substantial improvement) as well as find out that the morse taper on my tailstock quill is slightly marred from abuse in its previous life.

With parts only available for the lathe again by Feb next year, I'll try and get this old machine into as good a condition as I dare for now. It looks like i'll use a 45 degree countersink to clean up the slightly rough machining of the V groove on the tailstock slide and shim up the difference in height created. I'll set up the mill to be as paralell to the quill as I can and clean up the V groove. If I get close enough I might even scrape the ways a little using the ground base of my engineering square as reference.

Can anyone recommend someone who can grind a Morse taper quill for me in Pretoria?