Thread: metal lathe feed rate questions

You maybe missing some additional change gears.
Try the 30 driving the 127 and the 120 driving the 40,position your levers too E/2.\,this should give you .25mm pitch/.009".(30 on the stud).

Hi Peter,
Assuming the pdf is correct and that you have a 5/8" feed rod(I can see your hand wheel is on the right). The gearing you have 40-127-40 E2 powerfeed will give you 0.0029". My maths says if you change that to 30-127/120-40, you can make it 0.002"(most of that coming from fitting the 30tooth)

What makes you think its feeding to fast?
Have you measured how fast it is feeding?

Stuart

Originally Posted by Stustoys

Hi Peter,
Assuming the pdf is correct and that you have a 5/8" feed rod(I can see your hand wheel is on the right). The gearing you have 40-127-40 E2 powerfeed will give you 0.0029". My maths says if you change that to 30-127/120-40, you can make it 0.002"(most of that coming from fitting the 30tooth)

What makes you think its feeding to fast?
Have you measured how fast it is feeding?

Stuart

Morning Stuart
yes if I understand it correct , my lathe do have the 5/8" feed rod separately from screws feed. and separate lever for cross feed and cutting feed . there is the separate lever for screw cutting .
I tried E/2 and E/8 and I still see the feed faster than I need . reason i know is when I feed by hand the cutting improve and surface is much better than when power feed ,
I think there must be some different gears to change for different feeding rate ?
regards
peter

Originally Posted by pipeclay

You maybe missing some additional change gears.
Try the 30 driving the 127 and the 120 driving the 40,position your levers too E/2.,this should give you .25mm pitch/.009".(30 on the stud).

Thanks pipeclay.
I think you right. there must be some other gears that I didn't get them with the lathe .
I did set the E/2 but still too fast for my need .

Cheers'
Peter

Originally Posted by Stustoys

Have you measured how fast it is feeding?

If you dont have a dial gauge, the 50mm cut you are taking** in E8 should be taking around 32seconds.

**(assuming your 1250rpm is correct, the pdf says your max is 833rpm)

Do you have a picture of your tool?

Stuart

PS I hate using shimes to level a lathe.

Originally Posted by Stustoys

If you dont have a dial gauge, the 50mm cut you are taking** in E8 should be taking around 32seconds.

**(assuming your 1250rpm is correct, the pdf says your max is 833rpm)

Do you have a picture of your tool?

Stuart

PS I hate using shimes to level a lathe.

Hello Stuart.
here is some photos of the cutting finish and some tool i use as well as the lever for power feeding.
the lathe labled 1250RPM but I'm not sure if the motor is correct for that speeds .
regards
Peter

Peter,

For better results in brass, try grinding another tool with slight negative back rake, i.e. the back rake slopes down towards the nose of the tool instead of towards the front of the lathe. Give it a slightly rounded nose - not too much, or it will tend to chatter. This should give you almost a mirror finish in brass, but won't work on steel.

Frank.

G'Day Peter,
I had similar issues with an identical lathe, the lowest available feed rate at .0028"/rev was not fine enough for the finish I require for some projects . My solution was to cobble up a 50 tooth gear for the gearbox input and run a 30/127 x 120/50 gear train, this gives a rate of .0014"/rev (according to my DRO ) , Fig 1 shows the gear (scrounged from a Xerox printer) Fig 2 shows the finish I achieve on 30mm Mild Steel. Hope this is of some help.
Regards,
Martin

Originally Posted by franco

Peter,

For better results in brass, try grinding another tool with slight negative back rake, i.e. the back rake slopes down towards the nose of the tool instead of towards the front of the lathe. Give it a slightly rounded nose - not too much, or it will tend to chatter. This should give you almost a mirror finish in brass, but won't work on steel.

Frank.

Agree ..you are using a knife tool there Peter , you appear to have a neutral top rake and side rake . The tool you want needs a radius on the tip to get that smooth finish . Have you read Harold Halls book on Lathes ? He uses a fine honed edged radius knife tool for a finishing cut . The book is easy to buy on EPAY MIKE............BTW Martin, can you please do a close up pic of your tool tip .And , what was your spindle rpm ..THANKS

G'Day,
The tool in the photo is a Tesch single point diamond (picked up few of them at a Sunday market for $10 each years ago, but use them very sparingly) , my poxy camera wont focus close enough for a decent photo. Speed was about 200 RPM.
Regards,
Martin

Originally Posted by toolman49

G'Day Peter,
I had similar issues with an identical lathe, the lowest available feed rate at .0028"/rev was not fine enough for the finish I require for some projects . My solution was to cobble up a 50 tooth gear for the gearbox input and run a 30/127 x 120/50 gear train, this gives a rate of .0014"/rev (according to my DRO ) , Fig 1 shows the gear (scrounged from a Xerox printer) Fig 2 shows the finish I achieve on 30mm Mild Steel. Hope this is of some help.
Regards,
Martin

Hi Martin.
yes look like we got twinn but your look in excellent condition .
I will have to look for some gear to change on mine then . which model Xerox printer did you get the gear from ?
regards
Peter

Originally Posted by franco

Peter,

For better results in brass, try grinding another tool with slight negative back rake, i.e. the back rake slopes down towards the nose of the tool instead of towards the front of the lathe. Give it a slightly rounded nose - not too much, or it will tend to chatter. This should give you almost a mirror finish in brass, but won't work on steel.

Frank.

Hi Frank .
i have been told for brass you don't need any angle for the top rake . i tried to put the round nose on the tool but it give too much chatter.
i think my problem is the feeding rate . when I feed by hand i was getting much better result .

Cheers
Peter

excerpt from the wiki page on diamond turning: Diamond turning - Wikipedia, the free encyclopedia Ferrous materials are not readily machinable because the carbon in the diamond tool chemically reacts with the substrate, leading to tool damage and dulling after short cut lengths. Several techniques have been investigated to prevent this reaction, but few have been successful for long diamond machining processes at mass production scales. Diamond turning is most often used in infrared wavelengths because of the materials, surface roughness, and pick distance for the tooling.