Lead Screw #lathe


dave.tolan@...
 

For the gingery lathe a 3/8 16 lead screw is the designed screw. (~1.5mm per revolution)

I can get 10mm x 2mm trapezoidal lead screw.

This would mean changing the drive pulleys for this from 1:4 ratios to 1.4:5
4*4 == 16 (As designed)
4.5*4.5 == 20.25

I can get 10mm id / 12mm od tubing to make the bearing part, and trapezoidal nuts are also available.

Any thoughts on this? Good Idea? Bad? Why? Why not?

Thanks

Dave


John Dammeyer
 

Those are good questions.

 

Ultimately it really depends on how you want to use your Gingery Lathe when it's done.  A lot of people never ever thread anything.  They use taps and dies.  But there are occasions where it's better to use the lathe to thread.

 

For example.  The piece in the attached photo started out as a 55mm casting.  I needed a 6 degree taper to fit inside the milling machine spindle pulley so I could turn new pulleys.  I wanted to use the same nut to clamp it to this arbour. 

 

Since I have a South Bend 10L with a taper attachment with some trial and error I got it so the original pulley mounted perfectly.  The pulley was too large for the Gingery. 

 

I then needed to turn the 1.5mm pitch 50mm diameter thread on an imperial lathe in order to thread on the mill clamping nut.  Not something I'd have a die for.  So this is where the need for gears or computers come in.

 

Gears are way too complicated so I used my Electronic Lead Screw which only controls the Z axis (carriage) on the South Bend.  The turning of the long section and the threading were all controlled by the ELS.

 

Now take a look at the smaller picture.  It's got that same piece mounted in the Gingery 3 jaw clamping on that 6 degree taper.  One of the ELS users was having some issues so I demonstrated using the Gingery to turn an MT-3 angle taper on the horizontal section.  Here the Gingery has both X and Z controlled so tapers are easy as are all threads. 

 

I guess what I'm saying is as long as you can get between about 0.003" per rev and 0.010" per rev with your belt drive you can do all the turning you want without much chatter.  Once you want more than that you have to decide if you want to create a large pile of gears along with the 127:100 for metric or imperial conversion.  To make the gears you need a mill.  So it's quite involved.

 

I'd suggest, make your pulleys and use belts to create your turning feed rates.  That's what I did.  Then when I wanted to do threading I had to decide.  Again for the most threads you can use taps and dies.  Nothing wrong with that.

 

John Dammeyer

 

 

From: gingery-machines@groups.io [mailto:gingery-machines@groups.io] On Behalf Of dave.tolan@...
Sent: September-18-20 2:56 PM
To: gingery-machines@groups.io
Subject: [gingery-machines] Lead Screw #lathe

 

For the gingery lathe a 3/8 16 lead screw is the designed screw. (~1.5mm per revolution)

I can get 10mm x 2mm trapezoidal lead screw.

This would mean changing the drive pulleys for this from 1:4 ratios to 1.4:5
4*4 == 16 (As designed)
4.5*4.5 == 20.25

I can get 10mm id / 12mm od tubing to make the bearing part, and trapezoidal nuts are also available.

Any thoughts on this? Good Idea? Bad? Why? Why not?

Thanks

Dave


dave.tolan@...
 

Thanks John, that's a very comprehensive answer.
I'm going to go with the metric lead screw. 
If I ever get to threading on the lathe, Ireland is metric.
And I think the trapezoid thread will be better. It's something that I can redo relatively easily if I need to
Thanks again.


John Dammeyer
 

I originally used 3/8-16 with the half nut made of ZA-12 zinc.  No pictures that I can find.  By then though I'd bought the South Bend and I used it to cut a new ACME 10 TPI lead screw with shoulders etc. for the thrust bearings.  

 

And once I added the ELS I got rid of the half nut and created a zero backlash nut held in the carriage apron.

 

Gingery also screwed up in his design of half nut placement.  With it way off on the side it tends to want to twist the carriage.  Ideally you'd want the half nut on the center of the width of the carriage.  And of course you really want the carriage to be wider than it is deep.  His design has it square. 

 

Look around at commercial lathes and you won't find any like that.  They all have much wider bases compared to their depth.

 

I did start, with AlibreCAD, designing new drawings for the Gingery Lathe.  The idea was to use what I and others had learned and effectively write a new book with photos and proper CAD drawings to make a lathe that was more solid.

 

But, it's still less expensive to just buy a far east 7x14 if you want a lathe to make things.  OTOH, there is nothing that can replace the experience of building your own lathe.  I'm so glad I made mine.

 

John

 

 

From: gingery-machines@groups.io [mailto:gingery-machines@groups.io] On Behalf Of dave.tolan@...
Sent: September-19-20 12:06 AM
To: gingery-machines@groups.io
Subject: Re: [gingery-machines] Lead Screw #lathe

 

Thanks John, that's a very comprehensive answer.
I'm going to go with the metric lead screw. 
If I ever get to threading on the lathe, Ireland is metric.
And I think the trapezoid thread will be better. It's something that I can redo relatively easily if I need to
Thanks again.


Matthew Lloyd
 

The finer the lead screw thread, the finer control you will have of the carriage travel, and backlash in the split nut will not be as bad.  In that case, need to keep end play in the lead screw at a minimum.  A trapezoid screw might be good if the half nut clamps hard enough.

I do use my lathe to thread things on the odd occasion.  I have an old Aster lathe that I inherited from my grandfather, same as this, check it out http://www.lathes.co.uk/aster/

It looks pre-historic, but it is still accurate to 0.001 thou after more than 100 years of use, with half a thou run out in the chuck after I re-ground the jaws.  It also has cross slide feed which is a feature that many modern Chinese lathes don't have.  It's all I need for my hobby purposes at the moment.

Aside, I have found that you can do metric threads on an imperial lathe, with the correct combination of gears, but you must accept a small percentage of error.  In most cases this isn't a worry as it is very small, mostly 1 or 2 percent.

Choose a thread that is mathematically suitable to your learned units of measurement. i.e. inches or metric.  Then you will have no error.

I was always torn, as I did my apprenticeship as an engine re-builder in Australia, using inches and thousandths, but we are a metric country.  So i understand both and the relationship between them.

Another aside, on my lathe I have a 2hp 180V DC treadmill motor with a cobbled up SCR speed control with bridge rectifier to run it.  The motor pulley ratios aren't that important.

Regards,

Matt


On Saturday, 19 September 2020, 8:34:16 am AEST, John Dammeyer <johnd@...> wrote:


Those are good questions.

 

Ultimately it really depends on how you want to use your Gingery Lathe when it's done.  A lot of people never ever thread anything.  They use taps and dies.  But there are occasions where it's better to use the lathe to thread.

 

For example.  The piece in the attached photo started out as a 55mm casting.  I needed a 6 degree taper to fit inside the milling machine spindle pulley so I could turn new pulleys.  I wanted to use the same nut to clamp it to this arbour. 

 

Since I have a South Bend 10L with a taper attachment with some trial and error I got it so the original pulley mounted perfectly.  The pulley was too large for the Gingery. 

 

I then needed to turn the 1.5mm pitch 50mm diameter thread on an imperial lathe in order to thread on the mill clamping nut.  Not something I'd have a die for.  So this is where the need for gears or computers come in.

 

Gears are way too complicated so I used my Electronic Lead Screw which only controls the Z axis (carriage) on the South Bend.  The turning of the long section and the threading were all controlled by the ELS.

 

Now take a look at the smaller picture.  It's got that same piece mounted in the Gingery 3 jaw clamping on that 6 degree taper.  One of the ELS users was having some issues so I demonstrated using the Gingery to turn an MT-3 angle taper on the horizontal section.  Here the Gingery has both X and Z controlled so tapers are easy as are all threads. 

 

I guess what I'm saying is as long as you can get between about 0.003" per rev and 0.010" per rev with your belt drive you can do all the turning you want without much chatter.  Once you want more than that you have to decide if you want to create a large pile of gears along with the 127:100 for metric or imperial conversion.  To make the gears you need a mill.  So it's quite involved.

 

I'd suggest, make your pulleys and use belts to create your turning feed rates.  That's what I did.  Then when I wanted to do threading I had to decide.  Again for the most threads you can use taps and dies.  Nothing wrong with that.

 

John Dammeyer

 

 

From: gingery-machines@groups.io [mailto:gingery-machines@groups.io] On Behalf Of dave.tolan@...
Sent: September-18-20 2:56 PM
To: gingery-machines@groups.io
Subject: [gingery-machines] Lead Screw #lathe

 

For the gingery lathe a 3/8 16 lead screw is the designed screw. (~1.5mm per revolution)

I can get 10mm x 2mm trapezoidal lead screw.

This would mean changing the drive pulleys for this from 1:4 ratios to 1.4:5
4*4 == 16 (As designed)
4.5*4.5 == 20.25

I can get 10mm id / 12mm od tubing to make the bearing part, and trapezoidal nuts are also available.

Any thoughts on this? Good Idea? Bad? Why? Why not?

Thanks

Dave


Bill in OKC too
 

I LOVE your lathe! I want one like it!

You can get exact metric threads on any change gear lathe with a 127 & 100-tooth gear set. Finding those gears might be a problem. ;) I have a 7x10 Chinese mini-lathe, an Atlas TH42 10x24 lathe, and a South Bend Heavy 10L single-tumbler quick change gear box as a restoration project. It's the only one that might be hard to get to do metric gears. 

BUYING gears could be a problem only because they can get expensive. The gears for the Atlas are about 8-9" across, and upwards of $100 each. 

I bought a 3D printer to help with the process, but haven't gotten it complete yet. I have printed the 127 tooth gear for the mini-lathe. Have the file for the 100 tooth gear, but have a lot of other work to get done before I can get back to that project. 

Bill in OKC

William R. Meyers, MSgt, USAF(Ret.)


A human being should be able to change a diaper, plan an invasion,
butcher a hog, conn a ship, design a building, write a sonnet, balance
accounts, build a wall, set a bone, comfort the dying, take orders,
give orders, cooperate, act alone, solve equations, analyze a new
problem, pitch manure, program a computer, cook a tasty meal, fight
efficiently, die gallantly. Specialization is for insects.
LAZARUS LONG (Robert A. Heinlein)





On Saturday, September 19, 2020, 06:03:49 AM CDT, Matthew Lloyd via groups.io <m_g_l30@...> wrote:


The finer the lead screw thread, the finer control you will have of the carriage travel, and backlash in the split nut will not be as bad.  In that case, need to keep end play in the lead screw at a minimum.  A trapezoid screw might be good if the half nut clamps hard enough.

I do use my lathe to thread things on the odd occasion.  I have an old Aster lathe that I inherited from my grandfather, same as this, check it out http://www.lathes.co.uk/aster/

It looks pre-historic, but it is still accurate to 0.001 thou after more than 100 years of use, with half a thou run out in the chuck after I re-ground the jaws.  It also has cross slide feed which is a feature that many modern Chinese lathes don't have.  It's all I need for my hobby purposes at the moment.

Aside, I have found that you can do metric threads on an imperial lathe, with the correct combination of gears, but you must accept a small percentage of error.  In most cases this isn't a worry as it is very small, mostly 1 or 2 percent.

Choose a thread that is mathematically suitable to your learned units of measurement. i.e. inches or metric.  Then you will have no error.

I was always torn, as I did my apprenticeship as an engine re-builder in Australia, using inches and thousandths, but we are a metric country.  So i understand both and the relationship between them.

Another aside, on my lathe I have a 2hp 180V DC treadmill motor with a cobbled up SCR speed control with bridge rectifier to run it.  The motor pulley ratios aren't that important.

Regards,

Matt


On Saturday, 19 September 2020, 8:34:16 am AEST, John Dammeyer <johnd@...> wrote:


Those are good questions.

 

Ultimately it really depends on how you want to use your Gingery Lathe when it's done.  A lot of people never ever thread anything.  They use taps and dies.  But there are occasions where it's better to use the lathe to thread.

 

For example.  The piece in the attached photo started out as a 55mm casting.  I needed a 6 degree taper to fit inside the milling machine spindle pulley so I could turn new pulleys.  I wanted to use the same nut to clamp it to this arbour. 

 

Since I have a South Bend 10L with a taper attachment with some trial and error I got it so the original pulley mounted perfectly.  The pulley was too large for the Gingery. 

 

I then needed to turn the 1.5mm pitch 50mm diameter thread on an imperial lathe in order to thread on the mill clamping nut.  Not something I'd have a die for.  So this is where the need for gears or computers come in.

 

Gears are way too complicated so I used my Electronic Lead Screw which only controls the Z axis (carriage) on the South Bend.  The turning of the long section and the threading were all controlled by the ELS.

 

Now take a look at the smaller picture.  It's got that same piece mounted in the Gingery 3 jaw clamping on that 6 degree taper.  One of the ELS users was having some issues so I demonstrated using the Gingery to turn an MT-3 angle taper on the horizontal section.  Here the Gingery has both X and Z controlled so tapers are easy as are all threads. 

 

I guess what I'm saying is as long as you can get between about 0.003" per rev and 0.010" per rev with your belt drive you can do all the turning you want without much chatter.  Once you want more than that you have to decide if you want to create a large pile of gears along with the 127:100 for metric or imperial conversion.  To make the gears you need a mill.  So it's quite involved.

 

I'd suggest, make your pulleys and use belts to create your turning feed rates.  That's what I did.  Then when I wanted to do threading I had to decide.  Again for the most threads you can use taps and dies.  Nothing wrong with that.

 

John Dammeyer

 

 

From: gingery-machines@groups.io [mailto:gingery-machines@groups.io] On Behalf Of dave.tolan@...
Sent: September-18-20 2:56 PM
To: gingery-machines@groups.io
Subject: [gingery-machines] Lead Screw #lathe

 

For the gingery lathe a 3/8 16 lead screw is the designed screw. (~1.5mm per revolution)

I can get 10mm x 2mm trapezoidal lead screw.

This would mean changing the drive pulleys for this from 1:4 ratios to 1.4:5
4*4 == 16 (As designed)
4.5*4.5 == 20.25

I can get 10mm id / 12mm od tubing to make the bearing part, and trapezoidal nuts are also available.

Any thoughts on this? Good Idea? Bad? Why? Why not?

Thanks

Dave


dave.tolan@...
 

I agree that it's easier to just buy a lathe but where's the fun in that. I built my own boat a while back, see davesboat.blogspot.com. there's a certain magic to making something that just can't be matched with MasterCard.😉