Author Topic: Micro lathe refurb  (Read 22764 times)

Offline tangler

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Micro lathe refurb
« on: August 24, 2014, 03:17:23 PM »
 Making helical gears for the Wyvern involved a complicated and accurate set up on the Myford.  Breaking this down in order to turn a new blankto replace the one I'd just botched (several times  >:( ) convinced me that a second lathe would be useful.  Lack of space and using Jo's Cowells at Guildford has led me to look for a micro sized lathe (it's not entirely your fault Jo).

This one turned up on ebay. 









It's a middle period Flexispeed with back gear for good speed range, has the fine feed but no change gears for screw turning.  I can't imagine that I would want to cut gears on a lathe this size, the Myford can do that but it would be good for stud and bolt making with die cut threads.  Pick was reasonably local and the clincher was the fact that it came with a 4 jaw chuck of the correct small size for this lathe.  I already have 2 small watchmakers self centring 3 jaws with inside and outside jaws respectively.

It is quite crudely put together, most surfaces seem to have been prepared with a rather coarse grindstone but the design and iron castings are sound.  The spindle is mild steel in the cast iron journals and although there is some wear, there is sufficient adjustment in the split.  It will do for the time being.  The slides though need some attention. 
« Last Edit: August 24, 2014, 06:10:35 PM by tangler »

Offline Jo

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Re: Micro lathe refurb
« Reply #1 on: August 24, 2014, 03:55:07 PM »
(it's not entirely your fault Jo).

:mischief:

One cannot have too many lathes  ;)

Jo
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Online Dave Otto

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Re: Micro lathe refurb
« Reply #2 on: August 24, 2014, 04:02:04 PM »
Looks like a fun little refurb project.


Dave

Offline tangler

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Re: Micro lathe refurb
« Reply #3 on: August 24, 2014, 04:06:33 PM »
I've not really done much scraping before so this will be a learning experience.  I bought a far eastern scraper some time ago but have singularly failed to get any sort of edge on it to cut cast iron - I suspect it needs re-hardening.  I have a small random assortment of tungsten carbide tips so I put this scraper together:



It's not an ideal shape, I think more curve would be better but it seemed to work OK.  You can also see my surface plate in the picture.  This is planed but not ground.  However, I can't feel the ridges with my finger tips and a DTI registers no peaks or troughs.  Pictures of the scraping will be a bit thin on the ground - there was a lot of blue about which I was reluctant to get all over the camera.

The first task was to get the top of the bed flat.  After about 3 hours I managed this, there was a distinct hump in the middle which I could feel as a tight spot when traversing the saddle.



Next I flattened the nearside V which is the surface that the non gib side of the saddle rubs against.  I have a pair of machined parallels which are 1 x 3/4 x 9".  After testing with blue on the surface plate I found a good edge to use as a straight edge.  (Surprisingly good actually, I could almost lift up the plate with the parallel with a bit of blue between them - well, that's what it felt like anyway).  Another 3 hours or so and I had this:



I found the whole operation pleasantly satisfying, just had to remember not to keep rubbing my nose with blue fingers.

The next operation was to bring the outer V parallel with the inner.  This set up showed that there was a taper of about 0.006" over the length of the bed.  That's a lot of scraping :o . I decided to mill this off.

So, first I set the lathe bed  down on the parallels and machined the feet.



Then turned the bed over and used a dovetail cutter.  The forces are not really working in my favour here - you can see  the chatter marks which aren't quite as bad as they look, it's about 0.0005" between peaks and troughs



The dovetail cutter wasn't quite big enough to give the full depth so I had to remove the ridge with a file.  Alternating between the DTI and the straight edge I manged to get the 2 Vs parallel within 0.0005".



The little saddle was a rather more difficult prospect to scrape and I elected to just touch this up with the dovetail mill







The contact area was much improved (although the blue is a bit thick in this photo)

The headstock is fastened to the bed with 1 screw and a locating peg.  Having put the headstock back on the bed I tested for top to bottom parallelism.  I have a length of 1/2" ground mild steel which fits the journals perfectly.  Unfortunately, rotating showed it to be bent.  A length of Silver steel (drill rod) though was fine.  Surprisingly, top to bottom alignment seemed to be perfect. 








« Last Edit: August 24, 2014, 06:11:58 PM by tangler »

Offline tangler

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Re: Micro lathe refurb
« Reply #4 on: August 24, 2014, 05:21:27 PM »
Side to side alignment is controlled by the headstock pivoting on the pin and a slotted screw holding it in location.  I'm not really happy that this is a long lasting solution so elected to line everything up with the indicator



Clamp in position



and the drill through 1/4" for a roll pin




Disaster  :(  It slipped somewhere in the process. and is 0.02" out of alignment.  Plan B:  Remove the pin and drill out and tap 1/4" BSW as for the original screw and use cap head screws in both holes.  The headstock holes were drilled oversize to allow a little play.  Replacing the original screw means I can tighten it up using an allen key with the test spindle in place.



If that doesn't stay put I'll try putting some horizontal screws in (a la Myford) to bear on the rearward screw which will provide a more positive adjustment than hitting it with a hammer and also lock the rotation.

Offline tangler

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Re: Micro lathe refurb
« Reply #5 on: August 24, 2014, 05:34:05 PM »
The tailstock was not drilled through which I find a bit surprising since you can't use a knockout bar to remove the tooling.  It's a deep hole and very fortunately I have a 9/64" drill brazed to a rod that's left over from my bagpipe making attempt.  So I drilled as deep as I could with conventional drills and finished off with the special.  I can now use a 1/8" knock out bar.



The tailstock barrel had suffered some damage where the barrel rotation preventing stud had broken away.  JBWeld to the rescue!  I have one piece of PTFE which fortuitously is 1/2" OD.  Nothing sticks to PTFE (well it will but you have to etch with Hydrofluoric Acid)









I also made a couple of better looking hand screws for manipulating the tailstock



That's all for now.  Thanks for looking

Rod

Offline Roger B

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Re: Micro lathe refurb
« Reply #6 on: August 24, 2014, 05:39:10 PM »
That's a nice little machine and some good refurbishment  :ThumbsUp:  :ThumbsUp:
Best regards

Roger

Offline smfr

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Re: Micro lathe refurb
« Reply #7 on: August 24, 2014, 05:46:12 PM »
That's a lot of work there, Rod. This should be a very handy little lathe when she's up and running.  :ThumbsUp:

Simon

Offline ths

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Re: Micro lathe refurb
« Reply #8 on: August 24, 2014, 09:43:24 PM »
Nice work there Rod, very impressive work with the scraper, good tailstock mods.
Mine has the screwcutting and dogclutch, and it occurred to me to leave it set up at some useful thread (like 32 or 40 tpi), as the Myford has no gear box (and changing from slow self act is a pain).
I must take some photos, as it came from a deceased estate with every known Flexispeed accessory.
Looking forward to more.

Cheers, Hugh.

Offline John Hill

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Re: Micro lathe refurb
« Reply #9 on: August 24, 2014, 10:08:15 PM »
Very nice work Rod, it made me go out and take another look at mine. 

I was really impressed when mine arrived as it seemed to be so much more like a 'real lathe' than my little Adept lathe.

Hugh, I would like to see those photographs,  I got the original (I think) layshaft with mine which I understand is uncommon.

Here is mine after a cosmetic refurbishment.

Flexispeed lathe blue by MrJohnHill, on Flickr

Rod, if you dont mind, I will copy a couple of those enhancements you made to the tailstock.
« Last Edit: August 24, 2014, 10:12:35 PM by John Hill »

Offline tangler

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Re: Micro lathe refurb
« Reply #10 on: August 24, 2014, 11:18:11 PM »
Thanks for the interest guys.

Any mods I've made have been copied from somewhere else - nothing patented  :).  I haven't yet decided on the speed range either.  As it will be used for fairly small diameter stuff I really think it should go up to at least 2000 rpm, the bearings should stand it with adequate lubrication.  I'm still pondering what motor to use, I'd like to keep the whole package as compact as possible.  I've got a fairly small 1/6 HP induction motor that would do but I also have a brushed motor that I could use with a pwm speed controller but it's a bit noisy.  I could also try my 120w sewing machine motor.  The 1/4 induction motor that came with it is too much and anyway needs a pull on the belt to get it to go under load.  Any advice or pics greatly appreciated.

Cheers,

Rod

Offline tangler

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Re: Micro lathe refurb
« Reply #11 on: August 31, 2014, 12:43:24 AM »
I've been painting the castings.  While the spindle is out I've taken the opportunity to make a couple of fittings for the nose.  I bought 2 SC chucks from ebay, one with external and one with internal jaws, one of which came without a backplate.

Having found a suitable lump of steel, I drilled and then turned it to 1/2" BSF tapping size.



I then part turned the thread before finishing off with a tap, which is supported by a pump centre.





I then turned the  1/2" register



And tried the spindle for size



The spindle is 1/2" diameter through the bearings so I was able to mount it in a collet



Having parted off the backplate this was then screwed on to the nose for finishing,



and turned the register so that the intermediate plate from the chuck is a snug fit





The intermediate plate was used as jig for drilling and then tapping the mounting holes



I also wanted to make a chuck to use my ER25 collets.  I managed to find a big enough lump of unidentified steel.



I supported one end with a centre



Before skimming off the  outer skin - I think this was originally black hot rolled



I parted off to length, keeping the centre in until the diameter of the parting bridge was about 3/16"



Impressive coils from the Q cut parting tool, using power cross feed and at a good speed (800?) rpm



I turned this down to a suitable diameter for the register OD before reversing the job and mounting and clocking up in the four jaw independent

The ER screw thread is 32 x 1.5 mm.  My imperial Myford Super 7 lathe has a gearbox.  I used a method to cut metric gears that has been popularised by John Stevenson but was first mentioned (as far as I can tell) by The Rev. David Hoskin in Vol 171, issue 3955 of Model Engineer.  It involves substituting the 24 tooth spindle gear with a 34 tooth gear and then selecting 24 tpi on the gearbox to give a pitch of 1.499mm.





The ER half angle is 8 degrees so I set the angle up on the topslide using the Myford ER collet chuck



The first attempt at checking the angle with some blue was spot on  :o





I transferred the job to the Flexispeed spindle to make the final cut



Here is the selection of chucks,  I've cleaned up the 4 jaw and I had to make a key for it as well.  I was a bit worried that the ER25 chuck might be a bit lumpy for the little Flexispeed but it doesn't look out of place with the other chucks.



Cheers,

Rod






Offline Jo

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Re: Micro lathe refurb
« Reply #12 on: August 31, 2014, 01:32:01 AM »
 :naughty: This is being kitted out very nicely Rod.

Jo
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Offline Ramon

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Re: Micro lathe refurb
« Reply #13 on: August 31, 2014, 09:17:53 AM »
That's some nice work going on there Rod :ThumbsUp: that'll be a very nice little asset once done.

Love the build up work with the JBW by the way - that's one for the 'uses' file  ;) It will be interesting to see how well that stands up over the long term.

Regards - Ramon
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Offline ths

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Re: Micro lathe refurb
« Reply #14 on: August 31, 2014, 01:21:24 PM »
That is looking great Rod, and if you don't object, would you mind if I put up a photo or two of what I've got for my Flexi? I don't want to hijack the thread.

Cheers, Hugh.

Offline Allen Smithee

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Re: Micro lathe refurb
« Reply #15 on: August 31, 2014, 04:07:40 PM »
What sort of power are you looking for, and at what (motor spindle) rpm? I would say it's crying out for a small brushless motor, and if you're only looking for 200watts it would be dirt-cheap to do, as well as giving you full speed-control (and the intriguing possibility of being able to run from a car battery!)

If you're interested I can help you choose the components...

AS
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Offline ths

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Re: Micro lathe refurb
« Reply #16 on: September 01, 2014, 01:22:21 PM »


Hugh, I would like to see those photographs,  I got the original (I think) layshaft with mine which I understand is uncommon.

Hope this is OK with you Rod.

I purchased this about 4years ago via an eBay auction. It came from the estate of an O gauge modeller in the northern suburbs of Sydney. I don't know if he was the original owner, but it is little used, and in wonderful nick. What can I say? It came with all the accessories that were available for it, and the only one that might be expected to be here (travelling steady), was not, but I don't think Flexispeed made one. I have the manual that came with it, and it is not listed.



Here we have the lathe, mounted on the Flexispeed recommended (it's in the manual) drawer in cupboard. I have the drawer, but it's not in the shot. The motor is a Parvalux 1/4 HP, sprayed in the same Hammerite blue as the lathe. The countershaft is different to John Hill's, being a Picador product, as is the motor pulley. The drip tray is a piece of galvanised quad guttering, cut down and soft soldered to fit the purpose. An outlet, soldered in, may be discerned to the bottom left of the tray. A 12"/300mm ruler acts as a scale.

From left to right, backish row, gear cover with threading chart, swivelling vertical slide, change gears, 3 jaw chuck, 4 jaw chuck (I made the key), vise for the vertical slides, fixed vertical slide, fixed steady, faceplate, angle plate, headstock pulley cover.

At the front are a few things I've made for it, soft centre, 3/16" endmill holder, a revolving centre modified from one sold for the Seig C0, a holder for 13/16" dies, and an ER16 collet holder, which takes up to 10mm.



This shot shows the motorising side a bit better, as well as the change gears and the fine feed mechanism (but not very well). The fine feed is lovely, a double worm and wheel system that the makers say gives .0015" travel per revolution of the headstock spindle, and is separate from the change wheel system. Here I have the gears arranged to cut a 40tpi thread, but I'll be buggered if I can arrange it to cut anything but a very nice left hand thread. I wonder if I'll have to make a third banjo stud, given that for the required gears to mesh, an idler is necessary, which reverses the usual right hand cutting direction.

I've never done much with it, but have made an Elmers wobbler on it. Great on brass, struggles a bit on steel, but more to be found out. It's a baby, but a sweet one.

How fast could you run the spindle? Mild (I think) steel in cast iron.  I have a 24 v DC motor, ex mobility device, a power supply, and have ordered a couple of speed controllers...

Hugh.

Offline ths

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Re: Micro lathe refurb
« Reply #17 on: September 01, 2014, 01:46:26 PM »
I forgot to say, the manual has been scanned, PM for a copy. Hugh.

Offline tangler

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Re: Micro lathe refurb
« Reply #18 on: September 01, 2014, 04:44:24 PM »
Hugh,

Thank you very much indeed for sharing the photos.  My, that takes me back:  the very first lathe I ever used was exactly that model.  It sat at the back of the lab where I first worked.  I guess that's why I've been attracted to my Flexispeed, which is, I think, a generation earlier. I have PM'd you. 

I've had a couple of setbacks over the weekend.

With the paint dry (mostly - I'm a bit impatient) I've put the lathe together with a temporary motor system to work out what speeds and power I really need.



 I've made a couple of changes:  The handwheels had been modified to have rotating handles.  I don't like these so I hand turned a couple of new ones in stainless.  I' also made a Drummond type tool holder to fit directly on the cross slide in the hope that it gives me a more rigid option than the topslide.

The motor I hoped to use was this one:



It's a brushed Parvalux, rated at 1/10 Hp and 3,500 rpm.  I bought it second hand and it has had some work done on it with an NVR switch.  On no load it ran at 17,000 rpm and with countershaft system the slowest speed of the lathe spindle was 7,000   :o .  Presumably the torque was minimal.  Perhaps I'll make toolpost grinder someday.

This is a1,400 rpm 1/6HP induction motor which I use to drive the overhead gear on the Myford.



The starting capacitor, reverse and on/off switch live in a separate box which can be seen in the 2nd photo, so not really the compact system I'd hoped for.  I made an ally pulley for the countershaft to match the lathe pulleys which appear to be for an M size belt.  The countershaft itself was from an old home made power hacksaw I was given (and have since dismantled).  The drive belt is 6mm hollow urethane which is a) too small and b) old and brittle - it keeps breaking.  The pulley on the motor was the existing one.  The system worked well enough for a trial.



This system gave a maximum speed of 2,100 at the lathe spindle which I think is about right.  I can make a 2 speed pulley system for the lathe and countershaft to give me some more speeds.

I tried some trial cuts.  The lathe stalled very easily as the belt slipped on the lathe pulley.  Worse however, was the appalling chatter  :( .  I mentioned early on in this restoration that there was sufficient take up in the bearings to cope with the wear in the spindle.  I think I was wrong  :-[ .  I used the 1/2" ground silver steel and some blue to check the headstock bearings and they appear to be good.  The spindle was less so, with poor contact near the flange and the rear bearing only appeared to contact over half the diameter.   In this design, the end float can only be taken up by adjusting the pulley against the rear of the front bearing - which is strange because this need to be slackened off to engage the back gear (and is why, presumably, the pulley is cast iron,  to run on the spindle).  The large back gear pulley is fixed to the spindle by a grub screw.  As a test to see if the spindle was really the problem I mounted a length of 1/2" precision ground mid steel (the un-bent half for those kind souls who have been following this saga) in the headstock with the pulley and back gear.  These were fastened to the shaft with their grubs screws, the back gear taking up the end float.  It was very noticeable that the spindle needed a quarter turn of the adjusting screws to bring any pressure on the spindle while the PGMS needed barely a nip (it will be remembered that spindle measured 2 thou undersize).  I was also somewhat surprised that I need to ream both pulley and the back gear to get them to slide onto the shaft.  Perhaps the design was deliberately 2 thou under 1/2".



A trial cut was taken. 



Smooth as you like.  Something of a relief really but it does mean that I have to make a new spindle.  I've been trying to work out a way of using the PGMS but that means attaching the flange somehow.  I think I'm going to have to turn the whole thing and use an external lap to bring it to size.  I will also need to try and replicate the worm on the end - never done that and do I copy the wear?

Apart from that, the issues that still need sorting are:

 a)  the drive belts.  I'd ordered some cogged ZX belt which I'd hoped would be more flexible than the standard M size belt but my ebay supplier has failed to deliver.  Today I've ordered some 8mm urethane belt from GLR Kennions so I'll see if that does the job.  I'd like to keep the pulley centres small if I can to have a rather more compact set up than I've used for the trials.  Elastic belt would have the advantage that I would not need a tensioning device to change speed.

b) the motor.  I'd rather not use the induction motor since it has another life so, AS, I am interested in finding a compact motor with good torque and variable speed.  What can we do for 200W and a lathe spindle speed of 2,000 rpm?

Sorry about all the text,

Rod

Edited for nonsense

« Last Edit: September 01, 2014, 05:49:25 PM by tangler »

Offline Allen Smithee

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Re: Micro lathe refurb
« Reply #19 on: September 01, 2014, 04:58:46 PM »
Rod - what's the current reduction ratio (both with the pulleys you have there via the countershaft and/or if you were driving the countershaft directly)? 200-300w is no problem at all - I just need to know the motor speeds you're after.

AS
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Offline tangler

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Re: Micro lathe refurb
« Reply #20 on: September 01, 2014, 05:45:42 PM »
Hi AS,

According to my laser tacho the motor is running at 1470, the countershaft at 1142 and the lathe spindle speeds are 655, 1237 and 2170.  Clearly I didn't get my home made countershaft stepped pulley quite right since the middle pulleys are supposed to be the same size and should give the countershaft speed.

So, motor to countershaft is a reduction of  1.29 :1

Countershaft to lathe are 1.9 :1,  1:1 (approx  :-[)  and .55 : 1

The countershaft speed is about right so I guess it's how we connect the the motor to the countershaft.  If we have a variable speed motor then a single pulley, perhaps with a timing belt, would be fine so we could have quite a significant speed reduction if necessary.

Thinking out loud now:  The worm gear gives a very fine (I think .5 thou per rev) feed. A separate small variable speed motor driving this would obviate the need to cut a worm and thereby enable a proper end float adjustment outboard of the rear spindle bearing.  If we've already got a 12v supply.....

Cheers,

Rod

Offline Allen Smithee

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Re: Micro lathe refurb
« Reply #21 on: September 01, 2014, 06:10:59 PM »
So essentially if you want a maximum chuck speed of (say) 2500rpm you're looking for something that will drive the countershaft at roughly 1300rpm. If it was a staright DC motor operating from a 12v supply then (allowing for some sag) you' be looking for a motor of around 140rpm/v to drive the countershaft directly - this can be done, but it's an expensive solution. There are cheap brushless motors available with Kv ratings of 400-500rpm/v, so could you produce (say) a 3:1 reduction with a new motor-to-countershaft pulley? If so then the resulting motor would have loads of "headroom" (being rated for well over 40A continuous rather than the required 20ish) and would have continuously variable speed control. You may still want the gearing options in the countershaft pulley to increase the available torque when being used at lower speeds, although the torque at part-throttle should still be pretty good.

I'm fixated on 12v because it's very easy and cheap to get a 12v PSU rated for >50A, and that would just seem to simplfy things!

AS
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Offline Jo

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Re: Micro lathe refurb
« Reply #22 on: September 01, 2014, 06:17:44 PM »
Rod only the later high speed Cowells go up to 2100 rpm, it has an uprated lubrication system to cope and they also redesigned the headstock bearings to make them much more substantial. I put a second pulley on my earlier one to enable her to do the higher speed but I must be honest I prefer not to push her that high and normally run her at 800 rpm (same as C2).

Jo
« Last Edit: September 01, 2014, 06:26:07 PM by Jo »
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Offline tangler

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Re: Micro lathe refurb
« Reply #23 on: September 01, 2014, 07:52:37 PM »
Jo,

Thanks for that.  I was under the impression that the high speed version (4,000 rpm) used a hard spindle in bronze bearings but that the standard (2100rpm) used a soft spindle in cast iron.  I'll bear your comment in mind but I think I'd like the capability, at least, to go to 2000.  Lubrication needs to be good though.  ETW recommends that the split in this sort of bearing be filled with something elastic to stop the oil spilling out sideways, while still allowing some adjustability.

Cheers,

Rod

Offline tangler

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Re: Micro lathe refurb
« Reply #24 on: September 01, 2014, 08:12:59 PM »
AS, 

What are we looking at, bearing in mind that my experience of electric flight began and ended with a 540 motor and 7.2V nicads (with a Mole charger - remember them?). 

Something like this?

http://www.hobbyking.co.uk/hobbyking/store/__18178__Turnigy_Aerodrive_SK3_6354_245kv_Brushless_Outrunner_Motor.html

or are there bigger, torquier, slower, cheaper ones about?

So, if I understand correctly 12v x 245 gives  2940 rpm.  3:1 reduction should be doable.  What would I be looking for in terms of a PSU and speed controller?

Cheers,

Rod

Offline Jo

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Re: Micro lathe refurb
« Reply #25 on: September 01, 2014, 08:52:43 PM »
I was under the impression that the high speed version (4,000 rpm) used a hard spindle in bronze bearings but that the standard (2100rpm) used a soft spindle in cast iron.

 :facepalm: Another Cowells again: the CW, high speed watch makers lathe. Yes different bearings, nose spindle, variable speed control etc.

Mine are both the ME version but the later one was modded to allow for the higher 2100 RPM and less prone to break the headstock if you get heavy handed ;)

Jo
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Offline tangler

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Re: Micro lathe refurb
« Reply #26 on: September 01, 2014, 09:24:41 PM »
Hugh has very kindly sent me a copy of the manual for his Flexispeed.  "A long life can be expected form the spindle/bearings if the speed is kept below 1000 rpm".   In the configuration I got the lathe in the motor was connected directly to the lathe spindle.  Probably explains the chatter.

Thanks guys (and gal),

Rod

Offline ths

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Re: Micro lathe refurb
« Reply #27 on: September 01, 2014, 09:25:46 PM »


Mine are both the ME version but the later one was modded to allow for the higher 2100 RPM and less prone to break the headstock if you get heavy handed ;)

Jo

Jo, didn't you make headstock oilers for one of yours? Was that the high speed mod you refer to?

In regards to the PM Rod, I had another look at your photos on this thread, and  I can now see that it is an earlier incarnation, but later than Johns. His has the polished bronze reduction worm carrier, whereas yours has the painted casting, as has mine. Yours shares with Johns the brass/bronze apron plate, whereas mine is painted steel.

Hugh.

Offline tangler

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Re: Micro lathe refurb
« Reply #28 on: September 01, 2014, 09:43:35 PM »
My apron says "Flexispeed Sheffield", so before the Southampton concern..  I'm not convinced that the paint on mine was original.  It's satin bronze finish now though.  No point trying to get paint to stick to bronze when you don't need to.  The rest of the lathe is now is now Myford grey since I've had a tin of touch up enamel and never used it.  Must be 35 years old but was in perfect condition.

I have this even earlier one, missing the apron and lead screw.



Every thing is just that little bit smaller, much more like an Adept really.

Cheers,

Rod

Offline Allen Smithee

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Re: Micro lathe refurb
« Reply #29 on: September 01, 2014, 11:56:50 PM »
AS, 

What are we looking at, bearing in mind that my experience of electric flight began and ended with a 540 motor and 7.2V nicads (with a Mole charger - remember them?). 

One of the things I found when working on my garage/workshop clearance yesterday was a Mole cobalt 540 motor... :old:

Quote


Something like this?

http://www.hobbyking.co.uk/hobbyking/store/__18178__Turnigy_Aerodrive_SK3_6354_245kv_Brushless_Outrunner_Motor.html

or are there bigger, torquier, slower, cheaper ones about?

So, if I understand correctly 12v x 245 gives  2940 rpm.  3:1 reduction should be doable.

I will admit that when I first suggested this I hadn't appreciated quite how low the revs would be (at the motor) - I was assuming that the belt-drives would have an overall reduction ratio of around 6:1 or more! If that had been the case there would have been a range of suitable 28-36mm 40Aish outrunners around the 1000rpm/v mark costing from around 10. By the time you get down to below 500rpm/v things get bigger and more expensive! could you knock up another intermediate shaft in a pair of ball races with a toothed belt or gear reduction of 6:1?  That would certainly make things smaller and simpler!

Quote
What would I be looking for in terms of a PSU and speed controller?

For a speed controller I'd just look for a cheap one (but not an "opto" one) rated at anything over about 50A - that gives it the headroom to run with little cooling, and you don't need the bells & whistles of the more expensive ones. This would be controlled with a "servo tester" like this, which has a knice large knob on the front.

As for a power supply, I was going to suggest doing what I talk about in this article, which is cheap and reliable.

AS
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Offline Jo

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Re: Micro lathe refurb
« Reply #30 on: September 02, 2014, 07:57:11 AM »

Jo, didn't you make headstock oilers for one of yours? Was that the high speed mod you refer to?

Yes I made drip oilers for C1, which allows me to work for longer without having to add a drip of oil every 20mins or so which is much better. But I do have to watch I do not knock the oilers off when I use the chuck key. The later machine has flippy cap oilers, they do not hold as much oil but more than adequate for most normal operations.

But they redesigned the entire headstock on the later machines, the headstock cast was a bit thin either side of the bearings so they squared them up adding much more material.

Jo
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Offline ths

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Re: Micro lathe refurb
« Reply #31 on: September 02, 2014, 01:02:54 PM »


Jo, didn't you make headstock oilers for one of yours? Was that the high speed mod you refer to?

Yes I made drip oilers for C1, which allows me to work for longer without having to add a drip of oil every 20mins or so which is much better. But I do have to watch I do not knock the oilers off when I use the chuck key. The later machine has flippy cap oilers, they do not hold as much oil but more than adequate for most normal operations.

But they redesigned the entire headstock on the later machines, the headstock cast was a bit thin either side of the bearings so they squared them up adding much more material.

Jo

Do you think it is the rate of oil feed that allows the higher speed?

From memory, you made your oilers wick fed with cotton thread draped into the delivery hole, didn't you? How have they performed?

Sorry to sound demanding! I'm not.

Hugh.

Offline Jo

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Re: Micro lathe refurb
« Reply #32 on: September 02, 2014, 01:25:11 PM »
I think the rate of oil feed effect the streak down my walls  :LittleDevil: Without sufficient oil the headstock will get hot.

As long as I do not leave the tops off the oil pots when I am not using the lathe (which allows the oil to seep out all over the place  :() they have performed well.

But to be honest I made them last year and I did not do that much on C1 last winter as it was a warm year and I could happily go out to the main workshop in the evening. If it is cold this winter both C1 and Sexy will be getting more of my attention in the evenings in the week  ;).

Jo
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Offline Allen Smithee

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Re: Micro lathe refurb
« Reply #33 on: September 03, 2014, 10:00:30 AM »
At the risk of making a complete prat of myself and exposing my abject lack of understanding on this, can I ask a silly question? If you want to run at speeds higher than the plain bearings might allow, and given that it looks like you're going to make a new mainshaft anyway, is there any reason why you can't machine the headstock castings to take tapered roller bearings (or angular-contact ballraces) and then just adding a suitable flange at the front of the mainshaft and threaded collar at the back so you can preload them to eliminate the play? The lathe would then be good for much higher speeds (10,000rpm if desired!)

Just a thought,

AS
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Offline tangler

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Re: Micro lathe refurb
« Reply #34 on: September 03, 2014, 03:20:22 PM »
If you're a prat then you and me both!  I had seriously thought about that.  Unfortunately, I don't think there is enough meat in the headstock to fit rolling ball type bearings  :( .  My thoughts were that this would be a relatively quick refurb  :lolb:  so I didn't really want to make a new headstock.  I've got engines to make!  Since I'm making the new spindle (update later), I've decided to add a threaded collar at the back to take up the end float.  Even if I thread this 1/2" x 40 I shall need to lose some diameter off the fine feed worm to get the collar nut over it,  so it looks like the fine feed will have to go but I think the end float issue is more important.

Cheers,

Rod

Offline Allen Smithee

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Re: Micro lathe refurb
« Reply #35 on: September 03, 2014, 03:49:40 PM »
I see what you mean - would it be TOO tragic to use a smaller diameter mainshaft (so that tapered roller bearings could be accomodated), given that yo're not exactly going to want to use this machine a new flywheel for the QE2?

AS
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Offline Allen Smithee

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Re: Micro lathe refurb
« Reply #36 on: September 03, 2014, 05:13:53 PM »
...or failing that machine a rebate inside the ront and rear bearings and put poured white-metal bearings in them...

 :mischief:

AS
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Offline tangler

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Re: Micro lathe refurb
« Reply #37 on: September 04, 2014, 03:53:23 PM »
AS,

STOP right there.  This is taking up far too much time as it is   ;) .

The new spindle will be made out of this lump of Leaded free cutting steel.  In my naive way, I'm sort of hoping that the lead content may help with the lubricity.



I'm going to need an external lap so here's a lump of ally, drilled a half inch which should be oversize enough to slip over the spindle which will be turned to 1/2" + .002".



The lap needs a partial cut on one radius to allow it to compress



and a slanting cut through



This was an idea from an article by Duplex that Ron put up on his website http://www.modelenginenews.org/duplex/duplex_laps.html



before turning the spindle I thought it prudent to check the lathe for turning parallel by mounting the length of silver steel in the collet chuck



I turned a centre in the test bar



and checked the tailstock as well



All seems OK.  I turned the spindle to 0.502".  Micing it up showed a taper of 0.0005" with the small end at the tailstock (I wonder if this means that the tailstock is slightly high - could be a bit of swarf trapped underneath).  The lap would just fit on.



Here's the SiC powder and a little jar with some powder mixed with cutting oil.  I went straight to the 400 grit.  I think it took about 2 hours to get the spindle to 0.0002" over size all along. 



Very satisfying.  I finished off with another half hour of 600 grit.



The turning had left some cyclic variation in the right hand third which wasn't really evident until the lapping started.  It hasn't quite come out but we're going to lose that bit anyway.



Offline Allen Smithee

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Re: Micro lathe refurb
« Reply #38 on: September 04, 2014, 04:08:30 PM »
AS,

STOP right there.  This is taking up far too much time as it is   ;) .


<sigh> So typical of the youth of today - no time to do the job properly. Now a REAL engineer would be taking moulds from the headstock and digging a mine in the garden to mine the ore from which the iron will be extracted to cast into those moulds. That's the way we'd have done it when *I* were a lad, but these days everyone just wants the instant solution...

 >:D >:D

AS

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Offline tangler

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Re: Micro lathe refurb
« Reply #39 on: September 04, 2014, 04:35:27 PM »
I mentioned before that I want to add a locking ring to control the end float.  This is threaded 1/2" x 40tpi.  the M3 locking screws have both got brass pads on the end.



I held the lapped spindle in the collet to turn the register and nose thread, which I finished off with a 1/2" BSF (16 tpi) die.  I then turned the spindle around, held the register ind the collet and with tailstock support, cut the 40 tpi thread on the other end before finishing this with a die as well.

The lapped spindle is a snug but free turning fit in the journals.  I've also cut the recess for the pulley locking screw.



At this point I was still undecided about the fine feed worm, which is why I'd left that long thread.  Looking at the fit of the worm with it's wheel, the wheel is pretty worn.  I turned a shade over 16 thou off the worm radius ( that's the depth of the 40tpi thread) and there still seemed to be adequate engagement.  I decide to cut the worm off the old spindle and Loctite into a suitable recess in the new spindle.

The new spindle was mounted in the fixed steady, I'd used a Sharpie to mark where the position of the bearings so that the steady didn't score my freshly lapped surfaces.



I parted off the surplus end, drilled as much of the 9/16" through hole that I could manage from this end and bored the recess for the worm.



It remains to be seen whether the Loctite can cope with the torque of turning the lead screw.



I then remounted the the spindle in the collet and completed the through hole from this end.  I set up the topslide to cut the short 0 MT.  This shows a commercial full 0MT centre held between male and female centres.  Having used the DTI to set the topslide



I bored the taper and finished off with a reamer.



Trial assembly seems OK,



I've now glued in the worm so I'll wait a couple of days for the Loctite to go off before fiddling with it any more.

Thanks for watching,

Rod





Offline tangler

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Re: Micro lathe refurb
« Reply #40 on: September 04, 2014, 04:41:19 PM »
AS,

STOP right there.  This is taking up far too much time as it is   ;) .


<sigh> So typical of the youth of today - no time to do the job properly. Now a REAL engineer would be taking moulds from the headstock and digging a mine in the garden to mine the ore from which the iron will be extracted to cast into those moulds. That's the way we'd have done it when *I* were a lad, but these days everyone just wants the instant solution...

 >:D >:D

AS

That's probably why I became a physicist.....

Rod

Offline ths

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Re: Micro lathe refurb
« Reply #41 on: September 04, 2014, 09:16:20 PM »
Great update Rod, 2 hours on the lap earns a good outcome. I lapped the spindle for the UPT sensitive drill attachment, but I only had valve grinding paste! coarse and fine, fine leaving scratches so noticeable I used a bit of silver steel instead. I still have that piece of .375" steel in the drawer, too much the product of hard work to discard.

Hugh.

Offline tangler

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Re: Micro lathe refurb
« Reply #42 on: September 06, 2014, 04:01:39 PM »
I rather enjoy doing things like lapping these days, I guess (some) patience comes with age.   :old:

It doesn't look like the outrunner idea is going to work just at the moment - food for thought though, thanks AS.  I'm certainly interested in the concept.  One of my might come in useful one day is a motor salvaged from an AEG washing machine.  Most white goods seem to have very skeletal motors but this one is at least cased.  I've no idea of the power, somewhere around 1/6 HP I guess from the size. There is a particularly small pulley shrunk (?) onto the spindle.  I've now got some 8mm Roundthane belt so I was able to lash up the motor and countershaft.  Motor is 1480 and the countershaft speed is now 650 giving a max speed at the spindle of 1200.  There is still some slip on the lathe spindle pulley.  I haven't got particularly good tension here but I think there may be better options than the Roundthane.



As can be seen from this photo, there is a large capacitor to house somewhere and I think the motor will need some protection from swarf not to mention keeping the electrical connections away from the operator.  I'm currently toying with the idea of putting the motor in a box under the lathe.  The motor feet are temporary, there were just a pair of M5 holes tapped into the end casings.



The Loctite seems to be good enough to hold the worm in the lathe spindle   :) , I'm beginning to have trust in glue - the un-pinned Wyvern crankshaft shows no sign of failing either.

<a href="http://www.youtube.com/watch?v=6hof00q1E2A" target="_blank">http://www.youtube.com/watch?v=6hof00q1E2A</a>

I think that will do for now, I'm not really up for doing some woodwork just at the moment.  Thanks for your input guys,

Rod


Offline Allen Smithee

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Re: Micro lathe refurb
« Reply #43 on: September 06, 2014, 04:16:43 PM »
It doesn't look like the outrunner idea is going to work just at the moment - food for thought though, thanks AS.

No worries. We may shortly be trying an experiment using a small 150w outrunner to drive the drill in a UPT - we'll be posting the details if it works!

AS
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Offline John Hill

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Re: Micro lathe refurb
« Reply #44 on: September 08, 2014, 12:33:14 AM »
I found the local sewing machine repair man had some belts that are ideal for my Flexispeed.

Offline tangler

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Re: Micro lathe refurb
« Reply #45 on: September 08, 2014, 09:51:02 AM »
John,

Your installation is really neat.  The sewing machine belt I've looked at is too narrow for the pulleys on mine.  Yours seem to sit very nicely.  What width is your belt?

Cheers,

Rod

Offline John Hill

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Re: Micro lathe refurb
« Reply #46 on: September 23, 2014, 02:40:11 AM »
Rod, the sewing machine belts are 6mm wide.

John

Offline tangler

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Re: Micro lathe refurb
« Reply #47 on: September 26, 2014, 11:39:04 AM »
John,

Thanks for that.  Clearly our pulleys are different.  Mine seems to be sized for an M size belt (3/8" or 9.5mm at the top).  I've managed to source some 8mm cogged v belt which sits in the Vs OK and doesn't bottom.

http://simplybearings.co.uk/shop/Belts-V-Belts-VB+Classical+V-Belts+5+/+6+/+8mm-VB+Classical+V-Belts+8x5mm/c4601_4790_5053_5056/p680026/Optibelt+VB-8x315-Li+Cogged+Classical+8mm+Wide+5mm+Deep+V-Belt/product_info.html

Cheers,

Rod

Offline ths

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Re: Micro lathe refurb
« Reply #48 on: September 26, 2014, 01:43:49 PM »
What was the issue with the round poly belt? I've had no trouble with mine. Hugh.

Offline tangler

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Re: Micro lathe refurb
« Reply #49 on: September 26, 2014, 02:15:14 PM »
Hi Hugh,

6mm round belt was too small for the pulleys and the 8mm seems reluctant to wrap round the pulleys without putting, what I feel, is too much tension on the various pulley bearings.  Possibly I'm being over cautious but the V belt shouldl allow me to have closer centres and a more compact installation.

Cheers,

Rod

Offline ths

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Re: Micro lathe refurb
« Reply #50 on: September 26, 2014, 09:55:50 PM »
Understood. My 8mm belt seems to work OK, but I hadn't considered the bearings.

Cheers, Hugh.

Offline bp

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Re: Micro lathe refurb
« Reply #51 on: September 27, 2014, 04:26:53 AM »
About Loctite.  I don't think you need to loose any sleep about the effectiveness of Loctite.  Two examples......
1/  I used to work for Norton Motorcycles, a long time ago.  The steering stem, fork yoke assy was being redesigned.  Loctite was suggested as an alternative to the original brazing, to secure the stem into the yoke.  Considerable tooth sucking by the Big White Chiefs.  A test was set up, after curing, a push out test was performed, the Loctite joint remained intact, the surrounding metal sheared.
2/  When I was making my post/clamp-on QCTP, the height adjuster screw had a brass "foot" Loctited to the M5 set screw.  To keep everything in line the set screw/brass pad was loosely assembled into the toolholder.  Guess what happened.... yup, some of the Loctite migrated from the brass to the toolholder.  This was discovered after the Loctite had cured, an allen key now has a two turn spiral wound into it.  The toolholder had to be warmed up with a gas torch to destroy the Loctite.  That's why one of my (23) toolholders has a nice blue finish!!
cheers
Bill

Offline tangler

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Re: Micro lathe refurb
« Reply #52 on: October 21, 2014, 05:42:11 PM »
This turned up in the post today.  I saw it on ebay and couldn't resist.





Looks like somebody has had a go (and failed) at repairing the Tee slot with sifbronze or something similar.  I'm going to have to think about this  :thinking:

Cheers,

Rod

Offline ths

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Re: Micro lathe refurb
« Reply #53 on: October 21, 2014, 10:49:50 PM »
Same as one of mine Rod, good find. I don't know how much use mine will get, but it's certainly nice to add to a well rounded kit.

Perhaps you could mill away the central T cap ( for want of a better description), and screw/glue on a suitable piece of steel.

Cheers, Hugh.

Online steamer

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Re: Micro lathe refurb
« Reply #54 on: October 22, 2014, 12:50:19 AM »
3 screws and 2 pins in a flat piece of steel or Iron...Take a fly cut over the whole face when your done......

Done and dusted.
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline tangler

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Re: Micro lathe refurb
« Reply #55 on: October 26, 2014, 02:25:47 PM »
Screwing and gluing had occurred to me but I hadn't thought of pinning as well.  I guess closely fitted pins will stop any possible rotational movement.  An alternative might be to mill a tenon on the stub of the T and fit this to a slot for the new cross piece.  Or perhaps riveting right through with countersunk holes on both sides might do it.  That way the resultant repair wouldn't be obvious from the top surface after milling the whole lot flat

Thanks for your comments and helping me think about.

Rod

Offline tangler

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Re: Micro lathe refurb
« Reply #56 on: December 12, 2014, 12:18:46 PM »
Hi guys,

I finally finished the re-furb of this Flexispeed:



Closer inspection of the counter-shaft that I had been using showed that the bearings were shot.  So I bought a couple of pillow blocks from ebay.  The weight of the motor plus the counter-shaft provides adequate tension on the drive belt.  The box to the left contains the motor capacitor and an old reversing switch I have been hoarding for 30 years.





The DROs are those as used by AS for his mill, I haven't done the mains conversion yet.  At 30 each delivered they were cheaper than long scale DTIs.  The swarf covers are made from an ally extrusion bought from B&Q.  The scales are mounted with the sensing track underneath which should help to keep the swarf at bay.

Cheers,

Rod


Offline Allen Smithee

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Re: Micro lathe refurb
« Reply #57 on: December 12, 2014, 01:53:09 PM »
I do love that remote-mounting system for those scales!

I may be getting a unimat 3 in the near future and I may just copy that idea for it...

The DROs are those as used by AS for his mill, I haven't done the mains conversion yet.

If/when you do a little wrinkle I've discovered. I put a switch in the 3v cabple from the pwer adaptor, but (as you see above) the displays go into standby after a few minutes anyway. If you want to keep your datums just leave them in standby - touching any button wakes them up and they preserve the zero settings. On the other hand if you want an easy way to set a new zero datum on all axes at once - just cycle the power switch and Bob's your auntie. I've found myself using the power swicth to reset the mill when I've got the tool to my reference point (edge or circle-centre).

I would recomment using the mains PSU though, because even when switched off those displays will eat a pair of alkaline 2032 cells in about four days (or about six days for the lithium versions). The mains supply costs the same as about four batteries!

AS
« Last Edit: December 12, 2014, 02:01:25 PM by Allen Smithee »
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Offline fumopuc

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Re: Micro lathe refurb
« Reply #58 on: December 12, 2014, 07:39:46 PM »
Hi Rod, I like the re-furb of this lathe you have done there. This bearing carriers for the shaft will give the lathe the chance to survive for an other 100 years.
Kind Regards
Achim

Offline Roger B

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Re: Micro lathe refurb
« Reply #59 on: December 12, 2014, 07:58:28 PM »
Very nice job  :praise2:  :praise2: I also like the 'remote' DRO's. Something for me to think about I the future when I move out of the dark ages  :old:
Best regards

Roger

Offline Johnb

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Re: Micro lathe refurb
« Reply #60 on: December 12, 2014, 11:26:55 PM »
Nice job Rod.

One thing I've recently done with my Cowells is to do away with the weight of the motor proving tension alone. I've taken Jo's idea of holding the motor stationary against a spring. This improved the finish I've been getting noticeably.

John
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Offline Don1966

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Re: Micro lathe refurb
« Reply #61 on: December 12, 2014, 11:53:23 PM »
Outstanding job on the lathe Rod and just love the addition of the DRO'S.

DON

Offline ths

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Micro lathe refurb
« Reply #62 on: December 13, 2014, 11:10:12 AM »
Thumbs up for the DRO setup, but the whole project seems to have been a very worthwhile one. I can't recall, but did you make a collet chuck for it? Nice one to have finished by Christmas.

Cheers, Hugh.

Offline nevadablue

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Re: Micro lathe refurb
« Reply #63 on: July 10, 2015, 11:55:21 PM »
I know this an old thread, but I just had to congratulate you on the fine job of refurbishing the lathe and documenting it. Very enjoyable, THANKS! I got several ideas for one of my projects.

Offline Allen Smithee

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Re: Micro lathe refurb
« Reply #64 on: July 12, 2015, 05:34:05 PM »
I have just returned from visiting an old friend who has an old example of what appears to be this same lathe (but with a "zyto"? brand) which will soon be looking for a new owner. I didn't pay it that much attention, but it's painted a cream colour, and definitely has that helical-gear-driven leadscrew arrangement shown on this flexspeed. It had a tailstock and compound topslide.

If anyone is interested then let me know and I'll put you in touch. It's located on the Surrey/Hants border.

AS
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Offline tangler

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Re: Micro lathe refurb
« Reply #65 on: July 12, 2015, 06:01:45 PM »
http://www.lathes.co.uk/zyto/index.html

Bottom of the page.  Zyto was a brand name of Tyzack, the well known, at the time, tool factor.  Lots of badge engineering.

Rod

Offline Allen Smithee

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Re: Micro lathe refurb
« Reply #66 on: July 13, 2015, 08:26:04 AM »
The one I mentioned is now on HWS at 30

AS
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Online Twizseven

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Re: Micro lathe refurb
« Reply #67 on: July 13, 2015, 10:51:45 PM »
Rod, I somehow missed this addition of the dro's to the flexiispeed. Looks very good.   I wouldn't mind seeing a couple of closeup photos of the brackets you have fabricated.  Having recently fitted dro's to my cowells mill I quite fancy them on the cowells me90 lathe. I did use the magnetic read heads from machine-dro and use the yuristoys android app and his electronic design for the controller. I can use this for the lathe as well if I use the same readheads and magnetic scales.

Regards,
Colin

Offline tangler

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Re: Micro lathe refurb
« Reply #68 on: July 14, 2015, 11:50:15 AM »
nevadablue - Nice to to know the posts have been useful.

Colin - Here's a few more pics, hope you find them of use:









Cheers,

Rod

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Re: Micro lathe refurb
« Reply #69 on: July 14, 2015, 02:27:43 PM »
Haven't had a chance to comment Tangler,  but nicely done!

Dave
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Online Twizseven

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Re: Micro lathe refurb
« Reply #70 on: July 14, 2015, 07:49:19 PM »
Rod,

Many thanks for the photos.  That's given me confirmation of some of the ideas I had in mind.  I'm not sure whether its an optical illusion or not but there looks to be more depth of metal on the saddle compared to the Cowells ME90.  How many adjustment screws are there for the saddle gib.  I was thinking I had three, but it may be the one in the middle is to lock the saddle.  Do you have the third screw or have you removed it and the hole is it covered by your bracket.  I would need to leave a small hole in centre of the bracket for an allen key to lock the saddle.  One advantage of the magnetic read heads is that I would not require the covers over the scales, which might simplify things a little.  Both the scales and read head are fully sealed

The image below shows the brackets I made for the mill.



Hopefully I can make something similar.
 
Thanks,

Regards,

Colin
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« Last Edit: July 14, 2015, 07:55:04 PM by Twizseven »