Roughing cuts on Standard geared lathes

All discussion about lathes including but not limited to: South Bend, Hardinge, Logan, Monarch, Clausing and other HSM lathes, including imports

Moderators: GlennW, Harold_V

User avatar
Harold_V
Posts: 20232
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Roughing cuts on Standard geared lathes

Post by Harold_V »

Glenn Brooks wrote:The apron does have a lever on the right side that engages the half nuts for the power feed.
Only on the lowest of quality machines does the half nut lever get involved in ANYTHING but creating a thread. Better machines are built such that the screw portion of a lead screw is not used for anything else, so it isn't worn unnecessarily. (Many lathes have a slotted lead screw, with the slot driving the mechanisms discussed by Spro. Such mechanism provides feed for the carriage, and often the cross slide. Better quality machines use a separate rod for feeds, so the lead screw isn't even involved).
If I understand you correctly, the star knob also engages the power feed? But Do not engage both.
If your lathe has provisions for feeds beyond the use of the half nuts, then, yes, DO NOT ENGAGE BOTH OF THEM, as there would be a conflict of feed rates, resulting in something slipping, or even worse, something getting broken. More modern machines have interlocks that prevent such things from occurring, but they also typically don't have a star knob, but a lever, instead.
Still not,sure what the knob actually does.
Then you should try tightening the knob with the spindle of the machine rotating, with the carriage in free space, so if it moves, it won't be obstructed. If tightening the knob does nothing, then something is amiss. Do this with the half nuts open, NOT CLOSED.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
Hopefuldave
Posts: 148
Joined: Wed Jun 01, 2011 8:17 pm

Re: Roughing cuts on Standard geared lathes

Post by Hopefuldave »

Glenn Brooks wrote:Hi Dave, yep, you are right regarding the standard turning gearing on the Dalton: 24-24-96.

I will go count my TPI on the lead screw - probably 8, maybe 10 TPI.

I am trying to visualize how the math works out. I understand the 1:4 gear ratio easy enuf. However, how does one interpolate the .004" feed rate? Iam sure it has to do with the relationship to the leadscrew threads (TPI), but never thought about the math before...so,drawing a blank.

Once I understand that, probably could factor in different available gears to get possible coarser feeds.

Thanks much,
Glenn
Hi Glenn, the 0.004" feed is running the lead/feed at 1:1, 24-96-24 the 96 idler doesn't contribute to the overall ratio so you get the actual feed per rev of the shaft, which being geared direct from the spindle gives you that feed (assume 0.004") per spindle rev... if all my assumptions are right!

Dave H. (the other one)
Rules are for the obedience of fools, and the guidance of Wise Men - Douglas Bader
Hopefuldave
Posts: 148
Joined: Wed Jun 01, 2011 8:17 pm

Re: Roughing cuts on Standard geared lathes

Post by Hopefuldave »

Re engagement with halfnuts closed, agreed, DON'T! There should be an interlock to prevent that...

BUT... my lathe cuts a perfect 90 included cone with both feeds engaged, it's designed to! The taper attachment will take it to 60 included for centres etc. but it's easier to swing the topslide a bit....

Dave H. (the other one)
Rules are for the obedience of fools, and the guidance of Wise Men - Douglas Bader
Glenn Brooks
Posts: 2930
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Roughing cuts on Standard geared lathes

Post by Glenn Brooks »

Hhhmmm. Thanks all. Clearly I've got to go back and look more closely at how the apron works. Make sure iam doing things correctly, AND stating how the lathe works correctly. Particularly will look more closely at the star knob operation - which so far has seemed odd.

The Dalton is something of a fine old machine surviving from the early days (1905 to around 1929). Very stout and well made dor it's size. Unfortunately no operators manual or other written materials survive, if they ever existed. A bit of history: the smithsonian shows a Dalton in the Wright Brothers bicycle shop - used to make their aircraft that flew at Kitty Hawk. thousands were sent to Europe during WW1 for example. I've set a personal goal of becoming proficient in how they work, so far mostly by trial and discovery method...so appreciate your comments and advise. Sort of a virtual apprenticeship in Old School methods!



Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....
User avatar
Harold_V
Posts: 20232
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Roughing cuts on Standard geared lathes

Post by Harold_V »

Hopefuldave wrote:Re engagement with halfnuts closed, agreed, DON'T! There should be an interlock to prevent that...

BUT... my lathe cuts a perfect 90 included cone with both feeds engaged, it's designed to! The taper attachment will take it to 60 included for centres etc. but it's easier to swing the topslide a bit....

Dave H. (the other one)
It should be noted that the operation detailed above is for a lathe with powered CROSS feed. Such a lathe would have two star knobs. I can think of no example of using the one that powers the carriage being engaged at the same time the half nuts are engaged, as that is the condition I discussed whereby one would most likely damage the machine.

The Monarch EE has two levers for engaging power feeds, one for the carriage, one for the cross slide. It, too, allows for both to be engaged at the same time. Unfortunately, it does not yield a 90° angle.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.
spro
Posts: 8016
Joined: Mon Feb 20, 2006 11:04 pm
Location: mid atlantic

Re: Roughing cuts on Standard geared lathes

Post by spro »

Here's a link to the simple apron innards. http://www.lathes.co.uk/dalton/img82.jpg
Note that the "captive" worm and worm wheel are running whenever the lead screw is turning. The star knob just tightens the inner "clutch" section which has a spur gear contacting a reduction to moving the carriage / the same as the hand wheel. All this stuff is moving and needs lube :)
Glenn Brooks
Posts: 2930
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Roughing cuts on Standard geared lathes

Post by Glenn Brooks »

Thanks Spro. Finally I understand what the star knob is for. Makes perfect sense after the light bulb goes on! I went out to the shop this PM specifically to check it out. Tighten down, the power feed kicks in. Perfect!

Now I know why the,lead screw is in such good shape.

Here's a couple pics of my final configuration. Had to use a SB motor mount/countershaft assembly to provide power. Made the table top vertical support to anchor the tensioning handle for the countershaft assembly. Three (used) motors latter, the lathe runs really well.

The only major thing yet to do is find three more #000 drip oilers to lubricate the headstock and countershaft bearings. Only have one, haven't been able to find the proper size ( takes 1/8" NPT). Iam using a small oil cap off a miniature loco to oil the headstock. Not ideal but it works.
IMG_1294.JPG
IMG_1295.JPG
IMG_1296.JPG
IMG_1303.JPG
IMG_1297.JPG


Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....
spro
Posts: 8016
Joined: Mon Feb 20, 2006 11:04 pm
Location: mid atlantic

Re: Roughing cuts on Standard geared lathes

Post by spro »

I didn't know of all the differences. It appears the earlier had the DALTON casted on front of the apron. Ours have it casted across the front of the bed and the front of the apron is milled flat. Over 80+ years things change but it was and is a good lathe.
I've said this before; The headstock spindle is smaller thread while allows MT#3. Upon that lathe I bored and cut internal threads into a brass coupling. When that was right, with the register diameter true, it was placed on the spindle. The larger threads of this sleeve were turned on that lathe to shoulder and near the end, by turning pulley. The reason was because a 5" chuck is a 5 " chuck and would fit with a sleeve.
Glenn Brooks
Posts: 2930
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Roughing cuts on Standard geared lathes

Post by Glenn Brooks »

Spro, very interesting method to mount a 5" chuck. Something I might look at. My next goal with the Dalton is to adapt a face plate/drive dog plate and 4jaw chuck. Need to turn threads and diameter on a couple of used Atlas 1" ID faceplates I bought off eBay.

Yes, I also like the look of earlier Daltons with the name cast on the front of the apron. I think they also had nicely finished and rounded edges. Mine is a lot 5, so made late in the companies history- Around 1920 I think. Dennis Turk said the latter Daltons where a bit more robust and changed the maternal gearing in the apron, maybe the reason for changing the apron style.

Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....
Post Reply