Myford ml2/3 change gears

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Myford ml2/3 change gears

This topic has 16 replies, 6 voices, and was last updated 15 February 2025 at 20:31 by barry.

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13 February 2025 at 19:44 #783101
barry
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@barry
Hello, I have recently printed a 20/60, 20/65 and 20/60 for my Myford ML2/3 as seem in the picture below from the advice of Howard Lewis post from a few years ago. It dfoes not give a fine feed, looks more like a screw cutting. Any ideas on how to get a fine feed to work. It has not got the reverse lever on it.

On 8 February 2023 at 11:41 Howard Lewis Said:
The edarly Myfords were distinguished by the centre height and centre distance.

the ML 1 was 3.125 centre height, and was 15″ centres,, from memory (Dheck with Lathes UK )

The ML3 was 3.5″ centre height, 15″ centres, and the Ml4 was, like the ML2 a greater centre distance.

The thread for the chucl, originally was 7/8 BSW, (7/8 x 9 tpi ) but later was changed to 7/8 x 12 tpi.

Possibly, some of the very last were 1 1/8 x 12 tpi, but lacked the 1 1/4″ register used on nthe ML7

A peculiarity is that there is no gear in the Saddle so that moves the opposite way to the handle rotation.

i.e..Clockwise rotation of the handle moves towards the Headstock

The gears ar 20 DP, 14.5 PA but are driven, (by driving collars on the spindle and Leadscrew ) or compounded by 3/32 pins, rather than the keys used on the ML7.

The bore and width of 7 Series gears is the same, so by drilling through an existing gear, it can be used as jig to drill a 7 Series gear for use on the earlier Mls.

But try not to drill right through, so that the opin is retained.

Threads will be 1/4 BSF , mostly with a few BSW included. The gib screws ar probably BA.

For full details, look at lathes UK pages on the Ml1, 2, 3 and 4.

It may be ols, but if in reasonable trim is quite useabl.

It bmight be nworth getting an extra 20T or two, so that a fine feed can be set up 20:60/20:65/20:60 on the Leadscrew. This should give a fine feed of abouyt 0.004″ per rev. Yiou may need to fettle the spindle end of the banjo. to allow the stud to give good gear mesh.

The Tailstock barrel is prevented from rotating by a 1/4 BSF grubscrew with a key in the end that engages the keyway in the barrel. Once adjusted, it is secured by a locknut.

It might well be worth making an adaptor so that the later 1.125 / 1.25 register “standard” Myford fitting chucks can be fitted. I did this for somone who acquired a ML4, which we eventually got sorted and useable.

HTH

Howard
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13 February 2025 at 19:55 #783107
JasonB
Moderator
@jasonb
Take the 20T off the lead screw as it looks like you have that meshing with the 65T. You want the 20T behind the 65T to mesh with the 60T on the leadscrew. It should be small gear driving a large one on all studs and leadscrew.

so that a fine feed can be set up 20:60/20:65/20:60 on the Leadscrew.

From Howards post

20:60 = 20T on spindle drives 60T plastic 1 /

20:65 = 20T plastic 1 drives 65T Plastic 2/

20:60 = 20T plastic 2 Drives 60T on Plastic 3

No need for the last 20T on Plastic 3
13 February 2025 at 20:04 #783112
SillyOldDuffer
Moderator
@sillyoldduffer
I suspect the gears aren’t set correctly. They should all go from a low toothed driver to a high toothed driven. In the picture:

Red A is good

Red B is good

Red C! looks wrong: big wheel B drives a small wheel, so the ratio isn’t geared down. The small C wheel should be behind big wheel B and mesh with big wheel C (which is correctly positioned.)

Hope that makes sense.

Dave
13 February 2025 at 20:39 #783115
barry
Participant
@barry
Thanks for the quick replies. Have done what you suggested. They all mesh together now but I cannot fasten the lead screw gear. The gear B is now touching the lead screw shaft.

Thanks
13 February 2025 at 22:55 #783124
Howard Lewis
Participant
@howardlewis46836
I fear the you have made a gear with too many teeth, or put it in the wrong position.

You need another stage of reduction.

The set up that I made for a newbie, (A LONG time ago, so relying in memory) with a ML4 was;

20 tooth driver to 60T /20T compound to drive a second compound 65/20, which drove the 60T on the Leadscrew .

In this way the first 20:60 does not clash with the second 20:60 and the overall reduction becomes 29.25:1 giving a feed of 0.00473″/rev, which should provide a fairly fine feed..

Thinking back, this meant making up an extra stud (and had to fettle the slot in the banjo to incorporate the extra stud for the extra 20T and 60T)

The extra 60T was from a ML7, so had to be drilled for the 3/32 pin which connects the compounds together

It can be done!

Howard
14 February 2025 at 06:52 #783134
JasonB
Moderator
@jasonb
20 tooth driver to 60T /20T compound to drive a second compound 65/20, which drove the 60T on the Leadscrew

Howard that is what he has got in his second photo*. Problem is the 65 comes too close to the bit of lead screw that sticks out the end.

Might work with a gear a bit larger than 60T on the leadscrew which will push the 20/65 gear a bit further away if the banjo will allow it and gear won’t hit the drip tray.

* spindle gear may be a 25T
14 February 2025 at 07:02 #783140
Diogenes
Participant
@diogenes
Make a bigger gear for the leadscrew – I think a slightly finer feed will be a bonus anyway, nearly 5 thou is quite coarse.
14 February 2025 at 08:54 #783144
SillyOldDuffer
Moderator
@sillyoldduffer
Hope it’s simpler than “make another gear”, fingers crossed!

I’m not familiar with Barry’s ML so he will have to investigate. I’m guessing! Anyway, change Gears are mounted on a banjo, a device that allows gears to be mounted, slid into mesh, and locked in position. Not always straightforward. My mini-lathe’s banjo was an awkward cuss because, being designed to fit into a small space, it had two fiddly adjustable arms and a difficult to reach clamp nut. My WM280’s banjo is much easier; the gears mount into a straight slotted arm.

Not all gear combinations will fit into a banjo. Won’t go if the large and small gear diameters add up to being too big – colliding with a shaft or whatever.

Is the full capacity of the banjo being used? For example, in this case the gears at the spindle end probably need to be snugged to the end, and then the banjo, with cluster, angled to reach the lead-screw gear. Might be fiddly or the two big gears have to be swapped.

Other possibilities:
- Unlikely, but maybe a mistake in Howard’s advice. If it exists I can’t see it.
- The plastic gears were 3D-printed slightly oversize. Most 3D-printing uses STL files which do not contain dimensions and the print is scaled by the operator, a source of error. If slightly oversized, i.e. the cluster nearly fits, consider trimming the teeth back discretely in the lathe.
Dave
14 February 2025 at 09:28 #783148
JasonB
Moderator
@jasonb
You can’t just “snug up” the gear at the spindle end of the banjo as it will come out of mesh with the other gears, You build the banjo up from the leadscrew gear getting each successive gear to mesh correctly.

It’s far more than just a slightly oversize 3D print, it touches the leadscrew let alone the collar that is meant to go on and retain the leadscrew gear.

If you look at the finer pitches and feeds on other Myford charts the leadscrew gear is always larger than the next large gear of the pair before it. Howards setup has it the other way round.

If there is room on banjo and below the gear print a 70T to go on the leadscrew.
14 February 2025 at 10:11 #783152
JasonB
Moderator
@jasonb
This is the problem

If the 60T on the leadscrew is meshed with the 20T behind the 65T

Then the 65T comes too close to the lead screw which can be seen if you look from the headstock end

To cure this the leadscrew gear needs to be larger. Assuming the collar is 1″ dia then a 70T will do it provided the bango allows and it does not hit the drip tray

These are 20DP gears with 5/8″ bore
14 February 2025 at 10:56 #783158
Brian Wood
Participant
@brianwood45127
I have the original handbook from the era which quotes two versions of fine feed

114.4 tpi is given by 20:55, 30:60, 25:65

171.6 tpi is given by 20:55, 25:60, 20:65

Looking at the photo gives me the strong impression that these printed gears are much coarser than 20 DP, and therefore larger than will mesh happily in the space on the banjo.

Regards Brian
14 February 2025 at 11:10 #783159
JasonB
Moderator
@jasonb
Brian, The ones I have drawn are 20DP and show the same problem that the OP has so size would seem right.

The two gear trains you list are similar to what I said in that the leadscrew gear is 5T larger than the large one on the pair before.

Just doing the maths shows it won’t leave room for the collar.

65T gear has an OD of (65+2)/20 = 3.35. Half that is a radius of 1.675″

60T meshing with 20T have a pcd of 60/20 + 20/20 = 3 +1 = 4. Half that is a distance of 2″

5/8″ shaft has a radius of 0.3125″

So if you subtract the 1.675 and 0.3125 from 2″ then that is about 12thou gap which the collar will not fit into.
14 February 2025 at 11:41 #783179
JasonB
Moderator
@jasonb
Confirmed with CAD, 0.296mm ( approx 12 thou)between crest of teh 65T and the leadscrew when the 20T:60T pair are meshed.
14 February 2025 at 16:06 #783214
Brian Wood
Participant
@brianwood45127
Jason,

You have been more scientific than I was going by gut feeing alone on what I saw. Thank you for clarifying things.

Brian
14 February 2025 at 21:26 #783283
Howard Lewis
Participant
@howardlewis46836
The whole purpose of having the 65T gear in the middle of the train, is to increase the reduction ratio, and to prevent a foul between the first and final 60T gears.

Each 20:60 gives a 3:1 reduction, and the 20:65 gives a 3.25:1 reduction.

With two 3:1 reductions, in series, the overall ratio is 29.25:1, which with a 8 tpi Leadscrew will give a feed rate of 0.00427″ /rev.

The train that I have described has been set up and functioned, as intended, on a ML4, to produce a fine feed; not for screwcutting.

BUT, it did require an extra stud, and gears, some fettling of the banjo, and use of the tumbler reverse to ensure that the Saddle moved towards the chuck.

The original driving collars were used, as intended, to drive the first 20T driver and the 60T on the Leadscrew.

Howard
14 February 2025 at 21:53 #783289
barry
Participant
@barry
Hello, Thank you for all the replies. The problem may be I do not have a tumbler reverse as I said in my original post and have a single banjo. I am printing 55/30, 60/25 and a 65 for the lead screw as suggested by Brian Wood. Still printing at the moment will try again tomorrow.

Thanks again for all your replies
15 February 2025 at 20:31 #783443
barry
Participant
@barry
Hello again, problem solved, printed off the gears Brian Wood suggested from the original manual of 55/30, 60/25 and 65 on lead screw. It works perfect. Thanks again for all your replies and help.
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