lathe milling spindle?

[bertie_bassett]

hi guys, have had this idea floating around in my head for a while now but finally got it down on paper and thought id post it up here for criticism/improvements

like many hobby machinists I dream of having a mill to go with my lathe, but finding a good one locally one seems to be like unicorn hunting, so like many before me my thoughts have turned to milling attachments for my lathe.

after pondering over various milling attachments I came across an old articlee on converting the compound slide into the basis of averticall slide.  http://www.vintageprojects.com/machine-shop/lathe-millingattachment-plans.pdf
this seemed to be fairly simple to fabricate so I started trying to scrounge up some parts.

some more thinking and procrastinating I realised that iv only got an old worn 4 jaw chuck, so would also have to sort out a collet chuck to hold the milling cutters with . . .another job to the list. .

some more thinking and wishing I had an actual mill I started looking at diy milling machines (definatly out of my current capabilities) that got me looking at diy spindles and I came across a nice looking DC brushless spindle on a cnc site http://www.mycncuk.com/threads/3793-Diy-brushless-spindle

this really got me thinking . . hmm would be nice to have an independent milling spindle on that lathe, maby a tool post grinder, or a bit of profiling of things held in the chuck??  . . a third job to the list.. .

so I started looking at diy tool post grinder/spindles and doodling up ideas to mount the spindle on the yet to be built vertical slide.
everything I saw and came up with had lots of overhang and to me looked prone to twisting at inopportune moments.

then I asked myself a few questions

1. why am I trying to bodge up my compound to make a vertical slide, that will have loads of overhang and not be particularly ridged
2. why am I trying to bodge a nice diy spindle onto the side of a not very ridged vertical slide, creating even more overhang.
3. what do I actually want to accomplish with having this milling slide/spindle contraption?

so back to basics I went, and came up with a list of what I needed/wanted to do

1. mill key ways on shafts
2. profile edges of items
3. drill holes off center
4. drill radial holes in items
5. mill flats onto items
6. anything else I come up with along the way

now ideally id do all those things + more with a nice mill and a rotary table but that’s not happening soon, so what can I do with the lathe??

well the lathe has a built in rotary table, it called the headstock ;) and with a bit of tinkering I could even have it indexed
a tool post mounted spindle could then be my milling head, though id only have a x and a z axis no y but its a start

so lots more thinking ensued, how to solidly mount a spindle to the tool-post?? bolting onto the tool post looses rigidity, replacing the tool-post with a custom mount for the spindle would be better but how do I clamp it to the compounds t-slot and the compound isn’t as solid as id like to begin with. do I actually need the compound to use as a z axis?? etc  etc

finally I figured the most solid solution would be to remove the compound and to mount the spindle directly to the circular dovetail cast into the saddle, the z axis would be the saddle feed, but that should be good enough for me.

so a mounting block was designed, to bolt directly to the saddle and with a hole bored through at center height for the spindle, looking good now

but then the missing y axis kept giving me doubts about how useful this would actually be, and whether I could improve upon this design. . but how to create a solid vertical slide type affair for the round spindle?? and what to do about dovetails?

then it dawned on me . . . why does the spindle body have to be round?? why not square? that’s easier to bolt to things! and while im at it, why do I need dovetails? surely a square bodied spindle running in a channel would be just as solid for this contraption!

and so with a lot of hours sketching up things on the computer, creating cad drawings, modifying things to suit, re-checking sizes etc. I came up with this!




frame made from welded flat stock o a tuned base, brushless spindle to be fitted into the sqaure block and a bit of M16 studding for the screw.  et voila! simple solid toolpost spindle with height adjustmet 

[awemawson]

Are you familiar with John Payne's Quick Step Mill design? Hemingway does a kit, but it's a bit pricey, but may help with ideas:

http://www.hemingwaykits.com/acatalog/The_Quick_Step_Mill__.html

[bertie_bassett]

bugger . .  thought id done something origional for a change!

thanks for the link, that certainly looks a chunky beast , not sure that large a motor is required with the newer brushless motors around.
also with it only clamped in the toolpost i cant see it being all that solid a setup. though it has got use of the compound slide which could be advantagous.

[bertie_bassett]

well i got a bit of time to draw things up properly and have to say im quite pleased  with my efforts

http://

blue end will be an ER20 collet red bit is the motor

planned to make it mostly out of 40x10mm flat stock, witht the spindle being made from 40x40. height isnt yet set as ill have to do a few more measurments on the actual lathe and work out what is practicable.

[Fergus OMore]

Basically there was a Mr G.P.Potts of Troutbeck who made three spindles. One was tubular but similar to that depicted.
Another is the vertical adjustment on the Quorn and the other is the one on the little Stent tool and cutter grinder.
I gave the tubular device away to a friend but have the other two spindles and the Quorn and the Stent.

Digressing somewhat, the spindles of the Quorn, Stent and the Kennet are virtually interchangeable.

Most of the possibly original thinking is from the old ornamental turners. Holzapffel again!

Neverheless, the design seems quite feasible and interesting.

[bertie_bassett]

well after deciding to wait a while longer before getting a real mill I thought id resurrect this idea and get some parts on order.

amazingly took only 3 days to get an ER spindle and collet set from HK to my front door! and the rest of the bits turned up soon after.

best I get busy!

[Manxmodder]

bertie,it will be a really interesting thread for the reading if you decide to go ahead and post your progress.

Whether a user has a dedicated milling machine,or not,there are plenty of times when a motorised universal lathe attachment like you're planning is the more versatile option....OZ.

[PekkaNF]

Hi Bertie!

You may want to check the ER-collet arbor outer diameter. I ordered two 12 mm OD for nominal 12 mm ID bearings and it was a loose fit. Another looked "tight" but it was only a little carrot on the rear end. I know that folks have been using adhesive to stick the bearings on those.

Anyway those ER-collet arbors are soft, maybe next size could me turned down? from 1/2" to 12 mm or 16 mm to 15 mm does not sound that awful.

Pekka

[chipenter]

When I made my toolpost grinder the bearings were good push fit on the spindle , and the run out was under .ooo1" , I haven't tried an end mill yet at 12mm shaft anything over 1\8" may put to much strain on it .

[bertie_bassett]

Well I started making swarf a couple of days ago, had to modify the design slightly to get the bearings and motor to fit on the shaft length. Also added some registration between the parts to aid getting everything lined up. Now just waiting on some M4x 60  bolts to hold it all together.

Iv not actually measured the shaft but it slides easily into the bearings, so ill have to use some bearing fit anyway. I'll have to see how soft/ hard it is as I could do with tapping the end for a locking bolt. Surprisingly the shaft is also hollow so wont be as strong as it could be .

[Fergus OMore]

Mine are the two ordinary milling, drilling and grinding spindles from G.Potts that were sold as castings etc from Woking Precision Models which was taken over by Hemingway kits. there was also a tubular one- but I gave that away to a friend who was a watchmaker.

The other permutation that I have is the vertical slide from the Stent tool and cutter grinder but another possibility is the 'Myford' vertical slide and either the Quorn or the Kennet spindles.
The Quorn spindle, I recall, was utilised by the late Philip Amos to go on his Mill drill and serialised in ME.

My thoughts were that the casting on the Thomas Small Versatile  Dividing head( sold by Hemingway) had potential as a stronger spindle running in cast iron but could be returned to normal tasks fairly easily.
Even as it stands, it is quite a thing.

Regards

Norman

[bertie_bassett]

bolts arrived today so managed to get everything bolted together and ended up with this!

[RobWilson]

bertie,it will be a really interesting thread for the reading if you decide to go ahead and post your progress.

Whether a user has a dedicated milling machine,or not,there are plenty of times when a motorised universal lathe attachment like you're planning is the more versatile option....OZ.

I second above    , A milling spindle dose come in handy at times , thinking one day of building the quickstep mill 

Keep the build photos coming Bertie     , very interested to see how this build turns out 


Rob   

[bertie_bassett]

well managed to get a bit more time to play with things tonight and knocked up a 12v supply for a test run

didn't run it long as it needs stripping down and fettling, but all in all a good result I think.

seem to be running low on metal though so the actual frame may take a while longer to sort out.

when I disassemble ill try to take some more photos for anyone who's interested, and maby some drawings if autocad will load on this machine.

[mattinker]

Bertie,

I am very interested in your spindle as I am assembling the bits to make on myself. The thing that I haven't yet resolved is pre-loading the bearings, how have you gone about it? I have a 10mm ER20 spindle for mine   and I'm waiting for the motor to come back into stock.

Curious about your build, regards, Matthew

[bertie_bassett]

iv used double row bearings so think they are already preloaded??  however the spindle iv got is hollow so I may tap the end and add some preload via a bolt or if I cant tap the shaft I could use a draw bar type arrangement.

in regard to the motor, I struggled to find one in stock anywhere but eventually found one with a  different name but the exact same specs, ( and same name on the order form?)


if iv done this right heres a quick vid of a test run  :  try again : 

[mattinker]

Double row angular contact bearings should be preloaded. My "spindle is not hardened, I was thinking about a left hand thread on the outside. My problem is finding a suitable amount of preload using something like belleville washers.

Regards, Matthew

[bertie_bassett]

being as double row AC bearings are essentially a matched pair and they must already have a set preload, I don't think youll need to worry too much about and actual value for any extra you add.
using 2 x double rows isn't a normal application for these bearings as normally one end would be in a normal ball race and allowed to float, the way these are set up isn't 100% ideal but I think perfectly fine for my use.


iv managed to tap a short 6mm thread in the end of mine so can use a bolt and washer to add a little pre-load against the end of the bell housing, that should give the motor bearings some pre load to stop them skidding. I may add a small fan to the end as well to aid cooling

ran it for bout an hour this morning, was nice and smooth and only got warm to touch so I think its good to go as is. just need to finish up the z axis screw and fabricate the actual body.

drawings will take a while as my autocad 2002 cd refuses to install properly on this new laptop, will have to dig out the old one which has got the original drawings on anyway

also measured the run out and appear to be only getting 2 thou run out ( this was measured on the internal taper ) which im quite pleased with.

[mattinker]

Ok, I asked because I intend using two single row angular contact bearings! I would suggest Locktiteing the 6mm tensioning screw as it will have a tendency to unscrew if it's not a left-hand thread.

Regards, Matthew

[bertie_bassett]

ahh single row bearings will need a different approach,  easiest way would be to machine a spacer tube to go over the shaft between the inner races. pre load would change slightly with temp changes, but should be ok.
or you could put both bearings the same way round, and use a nut/bolt to add tension from the end, only problem with that is youll be adding lots of preload to the motor bearings

is there a reason your not using double row bearings? mine are only 30x14mm so would fit in most designs

yes ill remember to locktight the bolt in once im happy with everything.

[mattinker]

My idea was to pre-load by compressing the outer races using a bolt on cap and a spacer with spring washers in the inside. This puts no additional pressure on the motor bearings. My problem is how much pre-load and what sort of spring washers would be usable.

Regards, Matthew

[philf]

My idea was to pre-load by compressing the outer races using a bolt on cap and a spacer with spring washers in the inside. This puts no additional pressure on the motor bearings. My problem is how much pre-load and what sort of spring washers would be usable.

Regards, Matthew

Matthew,

Have a look at:

http://www.emmottsprings.co.uk/products/waved-washer-springs/

They're designed specifically for bearing preloading. In my milling spindle I used one between two deep groove ball bearings at the pulley end and precision double row angular contact at the business end.

Cheers.

Phil.

[vtsteam]

Bertie, which brushless motor did you get and what's the kV? I've got a couple large motors (EMP N5055 in 400kV and 580kV) I've been saving for motorized spindles, a 3/8 C8 ER11 spindle and a couple of power supplies, so I'll be very interested to see how yours works out.

One concern I've had is the relatively high RPM for power if cutting steel (and necessary very small mills). But I really haven't worked out what the requirements for these motors are yet. Aluminum, no problem, but I do wonder about steel.

Were you planning on running at 12 volts?

[mattinker]

Matthew,

Have a look at:

http://www.emmottsprings.co.uk/products/waved-washer-springs/

Thanks Phil,

that looks like exactly what I need!

Regards, Matthew

[bertie_bassett]

I managed to get hold of a xyh 6364 from giant shark, shows as out of stock but if you search for c 6364 or n6364 you can find the same .motor in stock??  Mines the 250kv one as its the lowest kv around. Should give a max speed of 3k rpm at 12v. Though I can rewind ut for a lower kv If required.
The vid I posted shows it running on 12v at max and minimum speed. If I go too low it starts stalling.
Iv not actually looked up speeds but It should be useable in steel with care and patience.
The 12v test was only really to see if it spins. I might mid the power supply for 24v but will probably just see how it goes.