Lathe improvements?

[Niels AbildgaardParticipant @nielsabildgaard33719]

The MeGa 50mm hole spindle is in and waiting for a 1.5kW/3000rpm/12 Nm industrial sewing machine motor.

The Spindle flange and tube is copperbrazed..

Screwed on flanges or chuck are dangerous due to the instantaneous stopping of motor.

[Ian PParticipant @ianp]

That certainly looks a substantial spindle assembly. Presume you have access to a large lathe and other engineering facilities to braze and machine a spindle of that size. (machined after brazing?)

I agree about the vulnerability of screwed on chucks but having gone to the trouble you have, why not elect for camlock mount?

Ian P

[old martParticipant @oldmart]

To match the oversized spindle bore, a chuck would have to be far too big for that little lathe, so the whole exercise is a futile wast of time and money.

[Andy PughParticipant @andypugh44463]

Posted by old mart on 24/11/2020 15:19:53:

To match the oversized spindle bore, a chuck would have to be far too big for that little lathe, so the whole exercise is a futile wast of time and money

This is a _model_engineering_ forum, the whole raison d'etre of which is to "waste" time and money.

And I disagree with the premise. It is frequently useful to be able to have larger diameter sections of parts on the opposite side of the chuck, even if the parts won't fit through the chuck.

And it is relatively easy to make the hole in the middle of a 4-jaw chuck larger, you only need to shorten the screws and bore out the body.

[Andy PughParticipant @andypugh44463]

Posted by Ian P on 24/11/2020 15:12:19:

I agree about the vulnerability of screwed on chucks but having gone to the trouble you have, why not elect for camlock mount?

I have made a Camlock mount. It's a lot of work.

http://bodgesoc.blogspot.com/2017/05/harmonic.html

If anyone fancies the idea, though, the cams are probably best bought, and were fairly inexpensive here:

https://www.gatemachinery.com/product/cam-d1-4/

Though they show out-of-stock at the moment.

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by Ian P on 24/11/2020 15:12:19:

That certainly looks a substantial spindle assembly. Presume you have access to a large lathe and other engineering facilities to braze and machine a spindle of that size. (machined after brazing?)

I agree about the vulnerability of screwed on chucks but having gone to the trouble you have, why not elect for camlock mount?

Ian P

The 125mm dia raw flange was machined on my 250 lathe that has been liberated by my son and the tube as well.

I worked at a copperbrazing site many years ago and the new owner did it at a fair prize..

If I knew where to get some Easyflow(No,No) I would have done it in garden.

The important step of turning thread and bearing seat in one go was done on my late 250.

The main zeal of exercise is to keep overhang from front bearing as short as possible and show the Chinese that they can do a better job within the given constraints.

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by old mart on 24/11/2020 15:19:53:

To match the oversized spindle bore, a chuck would have to be far too big for that little lathe, so the whole exercise is a futile wast of time and money.

It was one reason for giving my Boxford away and starting on this expensive and futile journey,that chucks were getting uncomfortably heavy.

Mass shall not exed my latest 50£ 125mm four independent jaw. It is incredibly precise and well made.

When I plane the two faces of a 90mm disc there is maximal 0.02 mm thickness difference.Often less.

Hole is 30mm and can easily (I think) be opened to 45mm.

A 160 mm independent four jaw would come with a 50mm hole but would be to  heavy for old men.

A 160 mm independent four jaws that has moving parts from the manufacturers line of 80mm chucks will be optimum and can be lower mass.

The standard workholding equipement for a 50mm bore 180/210 lathe can be:

An ER40 collet holder that can be adjusted say 0.1mm relative to spindle flange and cover 2-29mm dia:

Standard 3Jaw 125mm Chuck.My old PratBurnered has 36mm hole.

Standard 4 jaw 125 opened to 45-46mm and a low mass 160mm four jaw with 50-55 mm hole.

All mounted with front screws.On my 180 it takes less than three minutes to change fro 3 to 4 jaws.

Edited By Niels Abildgaard on 25/11/2020 08:48:05

Edited By Niels Abildgaard on 25/11/2020 08:50:32

[Matt HarringtonParticipant @mattharrington87221]

"…This is a _model_engineering_ forum, the whole raison d'etre of which is to "waste" time and money…"

Andy, never a truer word…..

Matt

[Ian PParticipant @ianp]

Posted by Matt Harrington on 25/11/2020 09:31:01:

"…This is a _model_engineering_ forum, the whole raison d'etre of which is to "waste" time and money…"

Andy, never a truer word…..

Matt

What a strange outlook!

Despite the title this is not just a forum for model engineers, who I am sure do not all waste time and money.

There are many avid user of this forum that have no interest on models or steam.

Ian P

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by old mart on 24/11/2020 15:19:53:

To match the oversized spindle bore, a chuck would have to be far too big for that little lathe, so the whole exercise is a futile wast of time and money.

Please find a picture of boring a 50mm hole in a 125mm four jaw chuck on a 180mm lathe with 30mm hole.

My 210 mm lathe is not running yet but has a 50mm hole in spinde.

Next picture shows how it will look on the 180 lathe ready for action.

I have not yet thought of an elegant way to cut the jaw screws.

They are hardened.

Any sensible objections?

[old martParticipant @oldmart]

From the photos, particularly the first, it looks like there will be very little left of the inner part of the screws when they are cut to clear the 50mm bore. The remaining flanges are all that will hold the jaws and the screws in the chuck.

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by old mart on 26/11/2020 19:28:23:

From the photos, particularly the first, it looks like there will be very little left of the inner part of the screws when they are cut to clear the 50mm bore. The remaining flanges are all that will hold the jaws and the screws in the chuck.

Instead of 9 flanges supporting the jaw I will have seven.

No big deal when in 35 to 50mm zone.

For smaller diameters I will use the 100mm four jaw enlarged from 25mm hole to 36mm.It is lower mass and more manegeable.

II am still thinking I will ask the manufacturer to make a ligthweigth 125mm/50mm bore  four jaw with screws and claws from the 80mm model.

Nicer for old toads.

If a reader has a 80mm four jaw can You please measure distance from front face to underside of screw hole like on picture?

Edited By Niels Abildgaard on 26/11/2020 19:43:20

Edited By Niels Abildgaard on 26/11/2020 19:44:07

Edited By Niels Abildgaard on 26/11/2020 19:44:54

[Thor 🇳🇴Participant @thor]

Hi Niels,

On my 80mm 4-jaw independent from ARC the distance is 29mm.

Thor

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by Thor on 27/11/2020 04:48:28:

Hi Niels,

On my 80mm 4-jaw independent from ARC the distance is 29mm.

Thor

Thank You Thor

On my normal 125 it is 36mm and mass is 5+kg.

With Your 29mm a independent adjustable four jaw 125mm dia slimline with 50mm borehole should be feasible with ca 4kg mass.Nicer and safer than 9kg for a standard 160mm version that has a 50 mm bore from factory.

Edited By Niels Abildgaard on 27/11/2020 08:40:30

[Thor 🇳🇴Participant @thor]

Hi Niels,

I have a lightweight (4.5kg) Indian 6 inch 4-jaw independent on my 290 lathe, the distance you asked is 31mm on the 6 inch and the chuck is about 45mm thick. As you say, the lighter chucks are easier to lift when you are old and have worn joints. I'm looking forward to see photos.

Thor

[Finn HammerParticipant @finnhammer30770]

Thanks Niels,

That link to the gears merchant is very nice

Cheers, Finn Hammer

Posted by Niels Abildgaard on 16/05/2019 15:21:49:

Cheap gears

The original spindle gear is 40 teeth module one and leadscrew 80 teeth.

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by Thor on 27/11/2020 10:18:14:

Hi Niels,

I have a lightweight (4.5kg) Indian 6 inch 4-jaw independent on my 290 lathe, the distance you asked is 31mm on the 6 inch and the chuck is about 45mm thick. As you say, the lighter chucks are easier to lift when you are old and have worn joints. I'm looking forward to see photos.

Thor

Hi Thor

Do You have a link to this range of chucks?

A 150 or 160 chuck on a 180 lathe is a little risky if the corresponding 125 can be bored to 50mm and be under 4 kg.

[Thor 🇳🇴Participant @thor]

Hi Niels,

My Zither 6 inch independent was purchased from ARC some years ago, I believe that ARC doesn't carry Zither chucks any more. I use the 6 inch 4-jaw quite often and consider it good value for the money I paid. ARC lists a slim body 2.5 inch under Clearance Items, others may still stock them.

Thor

[Niels AbildgaardParticipant @nielsabildgaard33719]

Hi Thor

It went better than expected to enlarge my 125mm four jaw.Trick was to keep screws fixed by blocking the jaws.

[Thor 🇳🇴Participant @thor]

Hi Niels,

Thanks for the photos, well done. Will enlarging the hole interfere with the jaw adjusting screws? I see your chuck can be mounted on a backplate from the front, makes things easier.

Thor

[Niels AbildgaardParticipant @nielsabildgaard33719]

Posted by Thor on 28/11/2020 04:50:13:

Hi Niels,

Thanks for the photos, well done. Will enlarging the hole interfere with the jaw adjusting screws? I see your chuck can be mounted on a backplate from the front, makes things easier.

Thor

The four jaw screws were cut in same operation as the chuck body.

Very healthy diet for a scrapped carbide cutter ,this mixture of cast iron and casehardened steel

[Andy PughParticipant @andypugh44463]

Posted by Niels Abildgaard on 28/11/2020 05:55:49:

The four jaw screws were cut in same operation as the chuck body.

I was a bit surprised by that. It isn't generally very difficult to get the screws out, and then the inside ends could be finished off neatly on a lathe.
Just remove the jaws and then tap the forks back with a punch. They are often only retained by the backplate.

[Niels AbildgaardParticipant @nielsabildgaard33719]

The screw forks are more fixed than the violence and screwdriver misuse that I like to apply.

I have cleaned up the boring and screws so that 48mm will pass and mass is 4.3kg.

[Niels AbildgaardParticipant @nielsabildgaard33719]

 

A Boxford VSL escaped my inhumane experiments and is in a good home where new owner also has pre WW2 Citroen Traction Avant.

Very classy company for a Boxford.

My cheap 210 that came with 38mm spindle bore has cut first swarf on its own new 50mm bore spindle.

It went very well but bearings are running much to hot.

It is very instructive to have a Watt meter before converter.

I made motor run 2000 rpm(Belt to spindle 4 to 1 ca) without belt and used 20 W.

With belt on but not cutting and same speed consumption was 190W and belt and bearings became much to hot..

Spindle nut was loosened and a hammer and woodblock worked and consumption sank to 120W.

Tomorrow the 125mm four-jaw with 48mm hole will be put on and we will try some real parting off.

Edited By Niels Abildgaard on 08/01/2021 19:56:50

[old martParticipant @oldmart]

Common spindle preload setup with taper roller bearings is just enough to end up warm to the touch but not hot, after 15-20 minutes at top speed unloaded. This would probably hold good with angular contact bearings as well.

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