Author Topic: Leadscrew handwheel for Myford series 7  (Read 15312 times)

Offline arnoldb

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Leadscrew handwheel for Myford series 7
« on: August 20, 2012, 02:00:06 AM »
Hi All.

I volunteered to make a leadscrew handhweel for the same friend I made the missing change gears.   As I have the necessary kit to do it, it would be a fairly quick job, and I was supplied with a nice hunk of aluminium to make it from - or so I thought  :Jester: .

Yesterday I started on the little project - the intent is to make a functional piece of kit similar to my own Myford-supplied original handwheel:


Easy, No ? - take the aluminum and turn it down to the same dimensions, graduate the markings and stamp some numbers...

That's what I thought until I really started looking at things, and how they work together.  Turns out, it's a bit more complicated than I thought.  The end of the handwheel with the slots in also functions as a thrust bearing surface against the bed-mounted bushings.  While the aluminium would work there, it's not the ideal choice for this application.  I drew up an out-of-focus C-o-C, looked at things, and decided that it would be better if the handwheel be made with a cast-iron bush pressed into it - so I drew that up out of focus as well  ;) :


In the last three-or-so years I've gotten to know all the bits my lathe came with, but one bit in a corner in the cabinet still puzzled me...  Yesterday I realised it's function; it was the original leadscrew spacer that was supplied with the lathe roughly 40 years ago!  The handwheel was an optional extra, and to fit it, the spacer had to be removed.  I could have used it to make the needed insert, but it's part of my lathe's heritage, and I'd prefer to keep it, so I cut a bit of cast iron from my stock to make a new one from:


A bit of turning, drilling and boring later, the cast iron bit looked like this:


Off to the mill to cut the slots - mounted on the rotary table as it's convenient to just screw the chuck on it to hold things:


Back to the lathe, and I coaxed a bit of shine from the section that would be visible after the press fit with a couple of strips of emery - (600 grit, then 1000 grit), then removed the workpiece from the chuck, mounted the 4-jaw chuck and with the workpiece flipped, clocked it in in the bore to be dead true.  Then I turned down the excess that was left to a bit under-size and intentionally left that section with a rough finish:


With the insert part done, it was off to the band saw to slice off a hunk of aluminium from the 105mm diameter stock provided.  This is pretty much bordering the limits of my saw, and I don't have a suitably "rough" blade in stock, so it had to chew through the workpiece with a 16 TPI blade.  I occasionally turned the workpiece to give the saw less surface to have to work on; things go a bit quicker then, and a steady drip of methylated spirits (rubbing alcohol if I'm not mistaken for you gents & ladies in the States - don't know what our friends Down Under calls it? ) helped lubricate and clear the chips off the blade's teeth:


On to the lathe, and this is pretty much as big a chunk of metal my 3-jaw chuck can handle without damaging its outside jaws and making the workpiece go rolling around the shop.  LIGHT cuts with a SHARP toolbit and LOW speed is in the order of the day!:


Faced off and turned down a bit:


Flipped in the chuck, and the outside diameter turned down, faced, and a 29mm deep hole bored to 28mm diameter - big enough to allow a hex socket fitting the leadscrew nut in the hole with a bit of clearance:


A bit of "cosmetic" work later:


And off to the mill to drill a 5mm hole to tap for an M6 thread for a handle:




Back to the lathe, flipped in the chuck, and some more turning and boring later:


The bore was a light press-fit for the cast-iron insert, and with some high-strength bearing retainer smeared on the previously-left-rough bit of the cast iron insert, - especially to provide space for the retainer liquid, I pressed it home with the tailstock drill chuck.  The aluminium part was still fairly hot from machining, and the cast iron insert cold, so things went together easily - the fit is about 0.01mm (halve a thou) interference :


Then I set up things on the mill to start graduating the handwheel.  Things went a bit haywire here; I'd originally intended to mark it out like I did on my rotary table , but there is not enough space to swing the cutter.

How now brown cow ?....

I ended up grinding a broken 2mm end mill to "shape" the markings on.  After a while making up the cutter bit, I had this setup:


All ready and raring to go; I just need to lock the mill's spindle - it doesn't have a lock, but setting the gear selectors to slowest speed is pretty darn locked up on the spindle and a little little light grooving with the tool won't even budge it ...  Nearly all set up. Great!.  So I need 125 divisions on the dividing head to finish the job... 

I ran Marv's DIVHEAD program after that and what do you know...  With the hole plates I have available for my dividing head, the result was:
Quote
NO SOLUTION WAS FOUND USING AVAILABLE HOLE PLATES
a plate with an integer multiple of 25 holes is required

 :rant: :rant: :wallbang: :wallbang: :facepalm: :facepalm:

Drat... Rats...  Darn It... Cr@p !!!  Not Marv's fault - I just used his program!.

So, now I need to either make an index plate with 25/50/75 holes, or I have to break down the setup as it was - well -"set up" - and use the rotary table to do the 2.88o per mark off that...

I need to think a bit now  :noidea:

Regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline steamer

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Re: Leadscrew handwheel for Myford series 7
« Reply #1 on: August 20, 2012, 02:33:37 AM »
I can make one for you if you like Arnold....let me know....

Dave

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Offline Maryak

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Re: Leadscrew handwheel for Myford series 7
« Reply #2 on: August 20, 2012, 03:10:21 AM »
Hi Arnold,

I dont' know what dividing head you have but........................

With a 90:1 worm

28 holes in 49 holes + 7 holes in 47 holes = 125 Divs. Actually 124.9366784 which is an error of slightly under 2 arcsecs per div.

Maybe useful and then again maybe useless.

I occasionally turned the workpiece to give the saw less surface to have to work on; things go a bit quicker then, and a steady drip of methylated spirits (rubbing alcohol if I'm not mistaken for you gents & ladies in the States - don't know what our friends Down Under calls it? ) helped lubricate and clear the chips off the blade's teeth:

Metho :ROFL:

Best Regards
Bob
« Last Edit: August 20, 2012, 05:28:27 AM by Maryak »
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Offline swilliams

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Re: Leadscrew handwheel for Myford series 7
« Reply #3 on: August 20, 2012, 03:32:36 AM »
Hope you sort it out smoothly Arnold. That handle sure looks big. Is it the same size as your original or bigger?

Steve

Offline zeeprogrammer

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Re: Leadscrew handwheel for Myford series 7
« Reply #4 on: August 20, 2012, 04:13:46 AM »
Drat... Rats...  Darn It... Cr@p !!!

For a second there I thought I was reading my own thread.  :Lol:
Until I noticed the misspelling.

I was really impressed with the finish and quality of the turning.
I'll get there someday.

Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Zee-Another Thread Trasher.

Offline arnoldb

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Re: Leadscrew handwheel for Myford series 7
« Reply #5 on: August 20, 2012, 11:19:20 AM »
Dave, thanks for the offer buddy; much appreciated  :NotWorthy: .  I'm sure I can knock something together here though  :ThumbsUp:

Thanks for looking in Steve  :) - the handle's the same size as the original.

Bob, thanks  :) - Ahh - Metho...  Have to hand it to you Ausies for your ability to shorten words conveniently  ;) .  60:1 Ratio on my DH; one thing I've never tried is compound dividing like you mentioned.  I know of it, but can't figure out how it's done... or at least how to do it on my DH  :-[

 ;) Of course you will Carl  :ThumbsUp: - the secret is hidden in some practice and tool honing - though this was definitely not my best turning job  :-X

Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline steamer

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Re: Leadscrew handwheel for Myford series 7
« Reply #6 on: August 20, 2012, 11:32:40 AM »
OK bud.....I'm watching!
 ;D
Dave
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Damned ijjit!

Offline tel

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Re: Leadscrew handwheel for Myford series 7
« Reply #7 on: August 20, 2012, 12:18:42 PM »
It's dead easy to do 125 graduations in the lathe Arnold - put a 75t gear on the spindle, mesh it with a 30 t (2.5:1 reduction) now key a 50t to the 30 and run around it 2 1/2 times - 50 x 2.5=125
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Online mklotz

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Re: Leadscrew handwheel for Myford series 7
« Reply #8 on: August 20, 2012, 04:54:18 PM »
If you think ordinary indexing is tedious and error-prone, stay as far away from compound indexing as possible.  Compound indexing is as convoluted as Egyptian fractions.  (Actually, the two have some similarities.)

Some years ago I wrote a program (not yet published) to compute compound indexing solutions using the standard B&S hole plates on rotary tables of various gear ratios.  With it I was able to show that the issue is confusing even for the authors of Machinery's Handbook.  Some of their published solutions are sub-optimal.
---
Regards, Marv


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Offline steamer

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Re: Leadscrew handwheel for Myford series 7
« Reply #9 on: August 20, 2012, 05:20:28 PM »
I think the easiest is to originate an index plate....various methods are around to get it pretty close.

then mount the plate in the dividing head and create a new index plate from the original.   the new one will have the errors averaged and reduced dramatically from the old one due to the gear reduction.

Now the plate is probably plenty accurate enough for gear work...let alone dial graduations. 

Dave
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Online Stuart

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Re: Leadscrew handwheel for Myford series 7
« Reply #10 on: August 20, 2012, 05:28:10 PM »
Arnold

its a pity you are not in the UK as Chronos has them for a ML7 for ?16 inc del that would have been cheaper than that lump of ali

but then again you would not have the pleasure of making it and showing us mortals how to


Nice work as usual  hope you have not been teaching Shrek any new words lately  :ROFL:  or has he been blood letting again


Stuart
My aim is for a accurate part with a good finish

Offline arnoldb

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Re: Leadscrew handwheel for Myford series 7
« Reply #11 on: August 20, 2012, 08:33:49 PM »
Many Thanks Gents  :)

Tel wins the grand prize  ;) - and even did the calculations for me - Thanks mate  :NotWorthy: Pure simplicity, and rarely seen or mentioned nowadays.  If it weren't for the fact that I had a couple of drinks with a business client this afternoon, I'd be dashing off to the shop now.  Hopefully I can get off work a bit earlier tomorrow.

Marv, I have to agree with you on the compound indexing; I've tried to comprehend it, but it beats me.  I'll try it one day though; just for the hell of it - on a simple project for myself. I find ordinary indexing strangely relaxing though... Between having to dial in accurate angle figures on the rotary table, and using the sector arms for indexing with a DH, I find the latter much less strenuous.  And my RT is simple to use as I calibrated it in decimal degrees rather than the absurd degrees-minutes-seconds standard that industry seems to favour for the most part.

Dave, if it were not for the fact that I'm a bit constrained for time (and suitable material), that's definitely the route I'd take.  In fact, one of my tuits is to make up the two index plates that I don't have, as well as a "general" one that I can take and just poke holes in as needed.  ;D when I started out, that error reducing was one of the hardest things for me to understand, till the penny dropped.  I can poke holes accurately to within 0.01o on my rotary table, so once run through my 1:60 dividing head, that makes for an accuracy of 1/6000 of a degree (0.000167o)  I wouldn't even bother making the second more accurate plate for use in my shop - just drilling the holes will have more run-out than the accuracy gained.  If I were to make a plate by using a paper template or manually laid out with a compass I'd make the second plate though.

Stuart, the pleasure and challenge of making it is why I do it  :ThumbsUp: In fact, I'm happy I ran into this little problem; it made people think and share ideas.  We all get to learn something from it. 
I'm as mortal as you and everyone else are - we're all just a bunch of people having a creative time in the shop.  I'm my own worst critic, and I do take the time to look at what I did last to try and improve on it based on my own taste.  Building model engines (or shop tooling for that matter) is actually a very individual pursuit, and is as varied as  each individual's preferences.  Some of us like a bit of bling, others of us just want the thing to work.  For some people the journey is the fun bit, while for others, it's about the end result.  There are no "bad" engine builds - I respect and enjoy each and every person who share's accomplishments as much as I do my own.
Shrek's actually on exemplary behaviour; he's molting right now and that means feathers can sometimes hurt, but even so, he'd just give me a firm "chew" without making the red stuff come out if I happen to touch one of those.  And he's not learned new bad words either; he does know the F-word, but only utters it if he happens to fall off his perch or drops a bit of cheese or peanut he's eating  :)

Back to the little indexing problem - I just had a horrible thought  :Lol: - there is also the option of setting up a 1:5 ratio gear train on my lathe from the headstock to the leadscrew; then I can index it using every fifth mark on lathe's handwheel - as it is already conveniently indexed.  Any slight error will be reduced by a fifth that way  ;)
 
Kind regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!

Offline tel

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Re: Leadscrew handwheel for Myford series 7
« Reply #12 on: August 20, 2012, 11:20:28 PM »
Quote
Tel wins the grand prize  ;) - and even did the calculations for me - Thanks mate  :NotWorthy: Pure simplicity, and rarely seen or mentioned nowadays.  If it weren't for the fact that I had a couple of drinks with a business client this afternoon, I'd be dashing off to the shop now.  Hopefully I can get off work a bit earlier tomorrow.

 ;D It's an old method, but one that is really handy at times. For my first 30 years playing this game I did so with nothing but the Myford, a small drill press and various home made bits for both. Even these days, when I have 2 vertical mill/drills, three lathes and a shaper, the technique comes into play often enough.
The older I get, the better I was.
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Online Stuart

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Re: Leadscrew handwheel for Myford series 7
« Reply #13 on: August 21, 2012, 12:53:54 PM »
Arnold

glad Shrek is Ok


If thats your lathe in the first pic

there is a mod recommended by Myford for the feed screw outer bearing  they recommend that you fit two 1/4 dowel pegs in the ally mount into the bed   so it looks  like a square of pins eg   


screw   dowel

dowel  screw


they found that the bracket could move and  bind

if you want a pic  i will photo my ML7 conny


Stuart
My aim is for a accurate part with a good finish

Offline arnoldb

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Re: Leadscrew handwheel for Myford series 7
« Reply #14 on: August 21, 2012, 10:22:17 PM »
Thanks Tel - It worked a treat  ;D - and pretty quick as well; took me just 2 hours to do, including making up a crude detent and doing all the set-up - I'll definitely be using this method again  :ThumbsUp: Just have to watch out for that backlash  :Lol:

Thanks for that information on the bearing mounting Stuart  :NotWorthy: - I understand your "words picture" perfectly  :) ; if I do detect any movement on that mounting in future, I'll do the mod.

Like I already mentioned, using the method Tel suggested worked very well  :)
I didn't get home after work earlier like I intended to today, as another social call came up, but I only had a coffee.  Today was a nice warm day as well, and it was still warm enough to head to the shop once I got home.

First order of the day was marking out the positions of the 5 and 10 markings on the 50 tooth gear with a marker pen:


Then I set up the gear train on the lathe - after carefully cleaning each gear's teeth with a toothbrush to make sure there were no bits of dirt in them.  Some form of detent was needed, so I eyeballed things and crudely poked a 6mm mounting hole in some 25mm square aluminium stock, and drilled and reamed another 6mm hole through it for the detent pin.  A scrounge-around supplied a spring that felt about right, and a bit of 6mm silver steel was ground to a V-tip on the bench grinder and cross-drilled to take a pin to retain a washer and the spring.  That lot was then assembled and mounted up on the lathe's banjo:

(click photo for a bigger image)

I set up the saddle-stop on the lathe bed (I must remember to get some 8mm rod so I don't have to use a drill bit as spacer), and mounted a thread-cutting toolbit on it's side on the toolpost - angling it slightly to get a bit of rake:

(also a clicky-photo)

While trying out a bit of a dummy-run without actually marking the workpiece, I checked the backlash, and as I expected, that is a major concern here; there's backlash through all the gears, and while some can be taken up by closing the clearance on the gears mounted on the banjo, the ones in the tumbler reverse is fixed - and adjusted for proper running while using the lathe's gear train while screwcutting.  So I worked out a simple method of selecting the correct position on the detent gear, then rocking the chuck lightly back and fro, and always stopping the rocking in the same direction with the same amount of torque.

I set out engraving the scale.  The first marking double-striked, as the initial infeed was a bit shallow  :-[ - We'll just call that the "Enhanced zero line"...  I first did all the "10s" lines 8mm long, using every second black mark on the gear to detent to.  The two "closer" 10s lines is not an error; with 125 divisions, there is just five divisions between the 120 line and the 0 line:


The 5's lines followed, each 6mm long using the marks on the gear that I skipped while making the 10 marks.  Then the thou marks followed each 4mm long, and using all the tooth gaps in the gear that was not marked.  Once done, it looked like this:


After de-burring, it looked a bit better  :):


I left things there for this evening.  Hopefully I can get the numbers stamped tomorrow evening without stuffing that up.

Regards, Arnold
Building an engine takes Patience, Planning, Preparation and Machining.
Procrastination is nearly the same, but it precludes machining.
Thus, an engine will only be built once the procrastination stops and the machining begins!