Myford 7 Carriage Handwheel Dial

[tangler]

Hi Folks,

I have found over the years that it would be very useful to have some indication, particularly when boring, of the movement of the carriage on my Myford Super 7.  Although I have a calibrated handwheel on the end of the leadscrew, this is not very convenient to use most of the time.  Other than this, I've not really felt the need for a DRO on the lathe - fitting seems to involve some compromises in lathe functionality, particularly now that I have acquired a taper turning attachment.  However, our very own Graham Meek has designed a suitable device that was published, firstly in Engineering In Miniature magazine and repeated in his Projects for your Workshop which I bought at the Alexandra Palace model engineering show.  One turn of the carriage handwheel does not give any sensible number that allows an easy calculation for multiple turns.  Graham has devised a gearing system that gives 1 inch of travel for one turn of the dial.  This involves the use of 36DP gears - 2 x 28 T and 2 x 26 T.  The description Graham gives for manufacturing the gears involves making a single tooth cutter but as I already have a Eureka backing off device it seemed a shame not to use it to make a circular Brown & Sharpe type gear cutter.

There are various table about that give the dimensions of cutting buttons and their spacings for making gear cutters, including Don's recent spreadsheet which was published just a couple of days too late for me!  I shall use it in future, very useful.  The first job was to mill the holder for the buttons to give relief when shaving the gear cutter - easily achieved with the digital gauge.





The holes for the 2 buttons were drilled at the same angle and spaced using the DRO



The buttons were made from silver steel (drill rod) and turned to size before hardening and tempering.  The tops of the buttons were then ground on the Worden to give some rake to the cutting surface





The buttons were the fastened into the holder with Loctite retainer, as was the arm for locating in the Eureka.



The cutter blank was mounted on the arbor that will be used to hold the finished cutter- both the lathe and mill use 2MT.  The working part of the blank was reduced to the correct thickness.



The button tool was the used to bring the blank to the correct profile by controlling the depth of cut according to the calculations from the data table





The next thing I need to do was to make the tooth gullets.  I find it quicker to use my milling spindle set up for this sort of job - setting items vertically in the mill is always a bit of a faff.  The vertical slide has a fixed scale on the feed so I can easily set the milling spindle to the lathe centre height.  The spindle was the adjusted so that the leading face of a embryo tooth was on a radius.  I used my GHT HDA to divide into 12 - five turns of the handle for each tooth.





Once the blank has its gullets, it is set up on the Eureka and the "topping cutter"  is used to relieve the top surface of each tooth



After this the button cutter is used to relieve the sides of the teeth to the correct profile



The finished cutter was then heated to bright orange with a gas torch and dropped into water.  I tempered it for 15 minutes at 190C in my little heat treatment oven



Time to go to bed now - more tomorrow

Rod

[Don1966]

Hi Rod, glad to see you post this and it's really a great reference for making your own cutter. Thanks for your input on the Eureka tool and how to use it. Looking forward to more of you post on the carriage hand wheel.

'Don

[Bjorn_B]

Nice work done here Rod!

First time I have seen a eureka tool in use in a online article! Very very nice to see!

What material are you using for the cutter blank, gauge plate?

My old Heidenhahn glass scale is allso using the taper turning mountings on the back of the bed (as most dro's do). Been thinking many times how to combine a dro with a taper attachment.. No idea on how to yet..

[Graham Meek]

Hi Rod,

You have made a nice job of making the cutter and I look forward to following the progress on this dial. I have been experimenting with a similar form of multi-tooth cutter manufacture. It is based on the single point idea, which is really an extension of the Button technique, but using a dividing head to present each cutting edge. Not as professional as your cutter but they work well.

My best regards
Gray,

[tangler]

OMG! the boss is watching  .  Seriously, the design is great.  (spoiler alert) -  I have finished the item and am very pleased with the result.  Measuring the travel with a long arm dti; 1 turn of the wheel was 25.35mm.  So my dear readers know what I'm on about, here is a picture of the finished dial in-situ.



This project needs some very careful turning to size since there are several press fits involved.  The drawings are in metric units and my lathe works in imperial but I have a digital external micrometer and a metric internal micrometer so although I mostly translated the metric instructions to imperial, I tended to move over to metric measurements for the final, critical sizing.  There are 3 major components: a backplate, a spindle and the dial as well as the four gears.  Like Graham's description, I started with the dial.  I already had some suitable lumps of free cutting mild steel, though not leaded as Graham recommends.   The hole through the centre is one of those that is critical so I sized it carefully.



The outside of the dial faces the operator needs to a have a rounded profile to match the existing dials on the lathe.  Graham recommends using one tooth of a milling corner rounding  cutter but I was happy to turn a 45 degree bevel and then  use a hand graver to round the profile.





The central band is knurled.  This is too big for my caliper type knurling tool so i borrowed one of the wheels from that to make this single wheel tool.  I'm not very happy pressing a single wheel against my lathe mandrel so the result was neither very deep nor very crisp but it works fine as a finger grip and actually matches the quality of the knurling on the other dials on the lathe.



The knurling was tidied up with this "other corner" tool holder



The dial needs engraving with 100 marks.  I used my G H Thomas Headstock Dividing attachment for the division - every 36 holes on a sixty hole plate.  I used the topslide as a planer and this simple carriage stop to get each line the same length.





I the went round again and lengthened every tenth mark - every six turns of the HDA handle



I stamped the numbers on using this set up in my GHT pillar tool





That's all for now, more later






 

[Don1966]

Beautiful job on the dial Rod, you do some very nice work. Good to see some GHT'S tools in use. I always get a lot of satisfaction using them.

Don

[Graham Meek]

Hi Rod,

Thanks for the update on the dial you are a braver man than me when it comes to using a graver. My hand eye co-ordination has never been that good, one reason I chose metal turning as opposed to wood turning. Up until a few years ago when I sold the manufacturing rights, I had always made these dials in batches of 25, so anything that saves a few minutes like forming the radius with a CRC is going to grab my attention. I bet you wonder how you ever managed without the dial now.

My best regards
Gray,

[pgp001]

Hi Rod

Just looking at the gear cutter you made, it might be the way it looks in the photo, but to me it looks like the front face of each tooth does not pass through the centre line of the cutter and the cutting face is leaning back with negative rake, Normally I would expect it to be on the centre line.

This page shows what I am on about.
http://www.diametal.ch/en/product/tooling/precision-solid-carbide-gear-cutting-tools/sharpening-errors.html

Good job on manufacturing it though, but you will have to be careful when sharpening it again.

Phil

[tangler]

Thanks for the comments chaps and, Phil, you're right - I'd never noticed!  I must have put it the wrong way round in the Eureka.  Fortunately it worked, I don't suppose I will ever use it again, let alone sharpen it.

The backplate is simple turning.  A bearing is pressed into the central recess so this another hole whose dimension is critical.  The diameter was just too big for my parting tool so I had to finish off the last 1/8" with a hacksaw.





The spindle sits over the existing shaft that the handwheel is normally keyed to, so this needs a key slot in one end and a woodruff key crescent in the outboard end for the handwheel.  The inboard end is sized to be pressed into the inner ring of the ball bearing.  (The bearing is a stock item from ArcEuroTrade here in the UK).  A gear is cut onto the outer dimension.  Here I'm using a slot drill to counterbore for the screw that holds the spindle onto the carriage shaft



The standard Myford woodruff key is 1/2" diameter by 1/8" thick.  As I have a 5/8" x 1/8" woodruff cutter in my collection I used this - I made my own key anyway from 5/8" silver steel. (which reminds me, Bjorn - the cutter was made from 1 1/4" silver steel).



One end of the spindle is completed



The keyway needs slotting but first a hole is drilled for the keyway to run out into.



I've not done any slotting before so this was a new experience.  I have some 1/8" square silver steel so this seemed the correct material to use for the slotting tool - hardened and tempered.



This mechanism came with my lathe.  It seems to be based on a design shown in Len Mason's Using the Small lathe .  It worked but the tool is really rather too slender and would have been better made out of 1/8" sheet gauge plate to give more rigidity.





Time to cut the gears.  I really needed to keep the speed down to 100rpm so as not to harm the carbon steel cutter.  I put the mill belts on to the lowest ratio and the VFD was turned down to just above minimum speed.  The motor was sat for a couple of hours at very low rpm but there was no hint of the motor getting even warm - it is sometimes suggested that at very low speeds there is insufficient airflow to keep the motor cool but this did not seem to be the case.  I cut the brass gears first before cutting the 2 steel gears.







The back plate needs a few holes drilling in it.  Graham gives the XY coordinates from the centre so I had to pick up that centre to zero the DRO.  There is a clearance hole to fasten the plate to the apron, a further counterbored hole for the gear assembly spindle and a counterbore on the other face to clear the end of a shaft that protrudes from the apron.  I drilled a small through hole for this so that I could pick it up when the plate was reversed.



The 2 intermediate gears were pressed onto a bronze bush.  These in turn slide onto a steel spindle that is held by a screw on the inbaird side of the backplate.  I had to ease this with a file slightly to get the gears running smoothly.



The large brass gear is a sprung fit inside the dial, so that it can be zeroed.  Graham shows a method for slitting this with a saw but I'm afraid I just used a junior hacksaw to cut 1/3 of the way through the diameter and then a longitudinal cut before slightly springing this flap out with a screw driver.  On assembly I got a tight spot on rotation of the handwheel which I eventually chased down to one of the gears rubbing on the inner surface of the dial.  I turned a couple of thou off the inner diameter and all was fine.  Prior to final assembly I blacked the dial (and some other bits for my taper turning attachment).



After blacking I returned the dial to a mandrel to polish up the engraving.  So,  here it is again:



It really is an excellent design.  It was quite a job for me since I was working to accuracies I don't normally achieve.  There are various jigs and fixtures to make as an aid to accuracy but these are not onerous and can be made from bits and pieces in the stub end collection.  The dial runs very smoothly, you can just about hear the gears whispering away when you move the carrriage and, even more surprising, there is no wobble.  I'm very pleased with a couple of days work - it would have been so much easier to make if I already had a carriage handwheel dial!

Thanks, Gray.

Rod

[fumopuc]

Hi Rod, that is just impressive.

[ths]

Very inspiring Rod, thanks. I have Grays book, time to get it out! Cheers, Hugh.

[Graham Meek]

Hi Rod,

Is the handwheel running any smoother now that you have fitted the dial with it's integral ball race? This is one mod that will improve the life expectancy of the poor Oilite bush. One chap years ago wanted his dial made with the backplate thicker to incorporate two bearings. A bit of an over kill but that was what he wanted, (the customer is always right).

My best regards
Gray,

[Allen Smithee]

Now that IS a handy-looking gadget! I hope you don't mind a couple of questions:

1. Is it really as simple as it looks?
2. Are those toothed pulleys and belt based on the MFA/Como items (which I had spotted a while ago as "gosh, they look good value - I must find a project that needs them!" items)
3. Is the shaft ballraced or running in plain bearings?
4. What sort of speeds do you run it at?
5. Is there anything else I need to know to copy it?

OK, so that's more than a couple, but I'm an engineer. Sticking to budgets is for lesser minds like accountants and project managers...

AS

[vcutajar]

Great job Rod.  Nicely done.

Vince

[tangler]

Guys,

Thanks for the comments.

AS,

Yes , it really is as simple as it looks






The vertical slide is the Myford  non-rotating item.  The spindle is an Arrand production, ball bearing and rated up to 8000rpm.  The spindle has a 1MT and is fitted with an ER11 1MT collet.  The motor was from  http://www.ebay.co.uk/itm/ENGINEERING-MINI-LATHE-120w-YDK-CLOCKWISE-MOTOR-PEDAL-/350453897010?hash=item5198ae1732:m:mro6hZqUkLpbEINpWyyIuGg  The belt came with the motor.  The only bit I made was the bit of bent steel for mounting the motor to the vertical slide.

Sadly it seems that Arrand are now defunct.  However, I bought an ER11 parallel shank collet chuck from ArcEuroTrade recently and noticed that the shank was very accurately ground to 12.00mm.  ARC also do some 12mm i.d. angular contact bearings so I also bought a pair of these and they are a perfect stiffly sliding fit on the ER11 shank.  I'm not sure whether the shank can have a thread turned on it for applying the pre-load but it is threaded internally at the end for M6.  I'm investigating the possibilies here.

Can somebody please tell me how to hide that web address under a hypertext link?

Cheers,

Rod

Edit: - forgot to add:  No load speed of the motor is 20,000rpm, no load speed connected to the Arrand spindle is 4000. It will happily mill or drill up to 1/4" diameter in steel, when the speed drops to about 2500rpm, although this can be lessened using the foot control - which I didn't think I needed but turns out to be quite useful as a hands free on/off switch and for soft starts when drilling.

[Bjorn_B]

Guys,

Thanks for the comments.

AS,

Yes , it really is as simple as it looks

I'm over-complicating things... Lesson to be learned here

Sewing machine motor?

[Allen Smithee]

Thanks for that, Rod.

I'm thinking more along the lines of using a drill-chuck, largely because I have a few spare ones and I don't really want to stock another range of collets and most of the use I can see for the thing is for indexed drilling rather than milling. So I'm pondering around a 12mm shaft with a J1 taper on the end, or perhaps a Morse 1 socket with an adaptor arbor so I can make one-of end-mill holders from blank-end arbors as I need them. Or perhaps an MT2 socket so I can use either my myford tailstock stuff or specials made from some black-end MT2 arbors which I happen to have

Actually now I think about it I have at least one quite good small drill-chuck that's on an M14x1 thread (from my unimat), so that would be another option to consider!

I'm not looking at a mains-powered sewing machine motor, but (again) thinking more along the lines of a 200w brushless motor with speed controller running from a simple DC power supply for a more compact solution.

Hmmm...too many options - more thought needed 

AS

[Allen Smithee]

OK, so I've had a really hard think during the boring bits of a day-long meeting at the IET today. I've come to the conclusion that this would be a very useful device, but I will almost certainly only ever want it for drilling holes and spot-facing - this will also increase the priority on completion of the 90% complete GH Thomas Headstock dividing set that I have...

So I'm drawing up something similar using angular-contact bearings, with a shaft to carry one of the many standard drill chucks I have lying around. I'll find the one that looks the most concentric and use that! But I'll size it for 12mm bearings so that, should I decide I need a decent collet chuck on it at a later date, I can use something like the Arc ER11 plain-shank chuck that you mentioned Rod...

PDR

[tangler]

ARC do an ER11 collet chuck with an internal JT1 taper, so if you can find a drill chuck with a JT1 taper...

You would probably only need one collet - 1/4" or 6mm for milling

Rod

[Allen Smithee]

Now you've gone and done it again! I was intending to do the spindle as either M14x1 male (to suit the chuck I have on the tailstock of my unimat 3) or a femal thread which I think is 3/8-BSF to suit the threaded stub on two old drill chucks I have lying around (I think they're prehistoric black & decker).

But it looks like I'm going to have to bite the bullet and turn a JT1 taper on the end of the spindle and get a JT1 chuck to suit it so that I have the option of the ER11 collet if I change my mind. I suppose if I turn the 12mm shaft and JT1 taper in one set-up at least I'll be getting minimal run-out in the chuck.

It was all so simple while I was doodling in that meeting!

Anyone got any clever tricks that make turning a 2.2074 degree taper  as simple just-do-it thing?

 

AS

[Steamer5]

Hi Allen,
 Don't you just hate it when your to do list jumps in size! I've got a project requiring a taper to be turned also......an ER 32 collet chuck for my Emco lathe.....anyway had an idea, First set the tool post square to the top-slide by what ever is your favorite method, currently mine is using a 1,2,3 block, loosen the top-slide so it can be rotated, set your digital or whatever pro tracker to the required angle, hold against the chuck & set the top-slide to it, now how to set it to the parts of an angle I'll leave to you to tell us!
 
Rod,
  That turned out really nice! Thanks to Grey for the design.

Cheers Kerrin

[Graham Meek]

Hi AS,

Have you considered making the spindle nose the same as the collet holder?

If I remember correctly the collet taper is a plain 8 degrees. If you make the spindle nose larger you would be able to go for a larger collet. Having a larger collet allows the manufacture of a special blank collet but with a JT taper, or internal thread, or external M14x1P thread to take a drill chuck. The only problem is you would need a dedicated collet closing nut for the drill chuck, unless the drill chuck is easily detached. OR why not just put a plain arbor on the drill chuck and grip it in the larger collets, this way you do not need the extra collet closing nut. It all depends on how accurate you need the set-up to be.

Just a thought!

My best regards
Gray,

[Allen Smithee]

Thanks for your thoughts, chaps. My usual problem with something like this is simply that I start with a concept for something that will do things I want to do, but within minutes this expands into all the possible things it COULD do (most of which I will never actually need), resulting in a set of requirements that define a design of a hundred times the complexity and/or precision which is such a challenge to make that I never actually do it!

So I've set myself some boundaries. First on the operational requirement:

1. I want to do be able to drill off-axis holes in the lathe, using my currently unfinished GHT headstock indexing/dividing attachment (so that needs to be finished as well).

2. The holes will all be axial (parallel to the spindle axis) so that the unit [held in a milling slide] can be mounted directly on the myford cross-slide "boring table" (not on the compound or the toolpost). The milling slide I'll be using will be this one:



3. Whilst drilling radial holes (90 deg to the spindle axis) might be useful I won't make specific provision for it. I already have some capability in that area because I can mount the mill/drill head from my Unimat 3 dorectly on the myford's cross slide, and anything that needs more than that can be done in my Seig X2p using my rotary table or my VDH (when I finish it - can you see a pattern emerging here?).

4. I want to be able to use drills and possibly reamers from "small" up to about 6mm/1/4" because I don't think the setup would be stiff enough to go much bigger, and this bounds the chuck size. This means I'm looking at spindle speeds in the range 200-6,000rpm, which means it needs ball-races rather than plain bearings. I'm assuming angular contact bearings to minimise the risk of chatter. The only milling capability I want to treat as a primary requirement is the use of slot drills to spot-face and/or counterbore to get flat seats for screws and nuts. This means that I'm probably going to get what I want from a drill chuck rather than needing collets.

5. Whilst being aware that at these speeds I could have some "toolpost grinding" capability it's not something I want to make particular provision for because I don't like grinding in my lathe (the shear amount of work involved in covering and protecting everything and then cleaning down afterwards).

6. Sewing machine motors are OK, but they are expensive and bulky for what they are, so I'm going to try using a cheap brushless motor operating from a 12-18v DC power supply at around 200watts. I've mentioned this before and have a bunch of suitable candidates in my spares boxes, so this is the opportunity to find out if it really does work. If it does this would make for a much simpler/cheaper solution to powering things like the UPTs

7. I happen to have a mild steel block which is 82mmx46mmx46mm that is almost exactly the same width as the milling slide. I think the 82mm dimension would be long enough to give decent support to the spindle, so this looks like the candidate chunk of metal to make it from!

AS

[Allen Smithee]

Rod,

I apologise - I've diverted your thread. I'll stop and start a new one. Please feel free to send your gamekeeper around to give me a sound horsewhipping!

AS

[tangler]

No probs.  It had already run its course.

Rod