Myford Gear train Configuration

[GavinB]

I need to know the factory settings for the gear train configuration of a myford
ML7.
When working the machine the carriage seems to travel too fast and leaves the work as if it's been screw cut, so need to know the numbers of the cogs on gear train and their order?

Thanks in advance
Gavin

 

[Hopper]

If you google Myford change gear chart all should be revealed.

In a nutshell, you want all the smallest gears paired with all the largest gears to get the finest feed. So if your spindle gear is a 20 or 21, it needs to be driving the biggest gear you have in your set. Then on the same stud it should be paired with the smallest gear left in your set. Which in turn meshes with the next largest gear in the set, coupled with the smallest gear left in your set on the same stud. And so on. Finishing with the largest remaining gear fitted to the lead screw.

Sometimes you have to shuffle the gears around to get them to physically clear each other but as long as you end up with a chain of small gear, large gear, small gear, large gear, small gear, large gear it will all work out ok.

 

[abby]

The gear train info for thread cutting and fine feed is in the back of the gear cover.

 

[GavinB]

The picture showing how is gone from mine, so I was hoping some one would have it/know what it was as everything on google seems to show screw cutting set ups, not smooth cutting.

Thanks
Gavin

 

[necchiom]

Hi Gavin. Maybe you forgot the picture...

 

[Hopper]

The picture showing how is gone from mine, so I was hoping some one would have it/know what it was as everything on google seems to show screw cutting set ups, not smooth cutting.

Thanks
Gavin

Your "smooth cutting" fine feed would be the finest screw cutting setting. Something like 300TPI would give you a feed of around about 3 thou per revolution that should do you for general purpose fine feed.

See the second to bottom line on the below screw cutting chart. It shows a fine feed rate of .0037 per revolution.
You need a 20T gear on the lathe spindle (aka mandrel), meshing with a 65 on the same stud as a 25T that then meshes with a 70 on the same stud as a 20T, which finally drives a 75 on the end of the leadscrew.

If you want to go one finer, substitute another 20T for the 25 and it will give you about .0018" per revolution -- as fine as you are ever likely to need.

 

[bmac2]

Hi Gavin
What I’ve been using is Myford ML7 gear calculator from Duncan Munro. Very simple to use and works in metric or imperial. Just enter the TPI, inches/rev or mm/rev in settings and let it do the dirty work. You can also customise the gear list to select only gears you actually have. Just make sure to check off Filter under the General Settings or it will give you a couple of hundred choices. oh:

Oh, and it’s free Thm:
http://metal.duncanamps.com/software.php

 

[Charles Lamont]

If you are to be adaptable in the shop you need to be able to do the arithmetic for yourself anyway.

The Myford leadscrew is 1/8" pitch. If you could have a simple train of two gears with a ratio of 1:2, say 25 & 50 teeth, with the 25 tooth driving, then you would get 16 TPI.

With a compound train you multiply the ratios, so, for the train shown for 64 TPI, 35:40 - 20:60 - 30:70 the pitch is:

1/8 x 35/40 x 20/60 x 30/70 = 0.015625.

Fine feeds are just the same. Smaller the driver, and and the bigger the driven wheels, the finer the feed, as Hopper said in his first reply.

 

[GavinB]

Thanks for your help guys, I posted this for my gramp and think he's got it working how he wants it now.

 

[Hopper]

That's great.
You should buy Gramps a copy of the Myford "bible" by Ian Bradley:
http://www.amazon.co.uk/dp/0852427751/?tag=skimlinks_replacement-20

It has all that Gramps will need to know to get up and running, plus more.