Thread: Metric cross slide screw.

Could any members that have a Metric Hercus lathe,either a 9" or 260 let me know the OD and pitch of there screws if possable.

If that maybe to awkward would you be able to let me know what a full rotation of the micrometer wheel is and how far the Cross slide actually moves with 1 complete rotation of the hand wheel,thankyou. (Dosent matter if distance travelled is given in Metric or Imperial).

Pipeclay,

I don't have a metric Hercus, so I'm not much help except to say, if you don't get a satisfactory response, try Mal at australianmetalworkinghobbyist.com.au

Mal is also a member here. His user name just escapes me at the moment, someone will know.

Ken

Hi Pipeclay,

this is my 260ATM19754, 1988 vintage, nearly unworn.

The threaded portion of the cross slide leadscrew is 160mm long, OD varies from 11.07mm at the beginning and 11.10mm at the far end. Pitch is 2mm. Measured with a caliper across 50 turns its as close as I can read 100mm. But I thought you may want to know more accurately....

Using a large face dial indicator of 50mm stroke and 0.01mm line spacing, I checked the travel of the cross slide for exatly 25 handwheel revolutions, and it came up with 49.99mm.
That is by all means a pretty impressive linearity.

With the cross slide optimally adjusted and freely moving, the overall backlash is 0.1mm. Again this is an excellent figure, especially if one considers that the leadscrew nut on this lathe is not slitted and thus has no provision to adjust backlash to compensate for wear. Many new Chinese lathe is 2 to 3 times worse. Even a new Schaublin is not much better.

This particular 260 has barely had 50 running hours since new, so I guess these are the figures you are after, presumably as a benchmark to make new spare parts for us, if I may guess?

Chris

Thankyou very much for that Chris,based on that information for the 260 I maybe headed in the right direction,just have to hope that someone with a Metric 9" can supply same.

allterrain50, that's Mal's username.

Ken

I spoke to him the other day on the phone and bought a steady off him last week. He's a super nice guy and I'm sure would do what he could to assist.

Pete

My 9" C-series has metric lead screws on the cross slide and top slide. Diameter of the cross slide screw, measured with a vernier caliper is nominally 11 mm. Measured with an imperial micrometer and arithmatically converted the diameter ranges 10.998 to 11.023 mm. Pitch calculates to 2.5424. ( 59 over 150 mm), so nominally 2.54. The micrometer collar onthe cross slide screw is graduated 25.4 per turn. Hope this is of some assistance.

Remarkably little visible wear on the screw, but significant wear on the bronze nut.

Rebo.

Seems confusing all of the threads that I have come across so far have been close to 2mm pitch,not exact but close,not close enough to actually call it 2mm.
The dimensions that you have listed would fall closer to an Acme thread of 10 tpi and 7/16" diameter.
You wouldnt by any chance have an idea of when it was made.
If you can supply the machine Number either located on the Change gear panel,right hand rear of the bed or tailstock I should be able to get a fair guess as to the manufacture year.
Going by the figures I am guessing at the moment some where between 1973 to 1976.

Seems to me that Pipeclay's thinking is correct, Rebo's lathe is imperial with metric dials - something that I am tempted to do on my imperial Colchester Bantam as all my measurement tackle is metric.

Eg: my crossfeed is pitch 1/5 inch, 200 thou, 200 graduations of 0.001 inch equals 5.08 mm.
Tempting to make a new dial with 200 graduations of 0.025 mm giving 5 mm, an error of (-) 0.08 mm per revolution.
When turning, a micrometer measurement then an adjustment on the dial according to the error, results in less metal than desired being removed.
If aiming for, say, a reduction of 0.05 mm ( 2 thou ), the new metric dial would deliver a cut too small by less than 1 micron - too small to worry about.

The same argument would apply to the Hercus 1/10 inch crossfeed leadscrew, just halve all the numbers.

Anyone else tried metric dials on imperial lathes ?

Note:
If I go metric, I will make it 10 mm with 200 graduations of 0.05 mm corresponding to the diameter - as found on industrial machines.

John.

Originally Posted by Rebo

My 9" C-series has metric lead screws on the cross slide and top slide. Diameter of the cross slide screw, measured with a vernier caliper is nominally 11 mm. Measured with an imperial micrometer and arithmatically converted the diameter ranges 10.998 to 11.023 mm. Pitch calculates to 2.5424. ( 59 over 150 mm), so nominally 2.54. The micrometer collar onthe cross slide screw is graduated 25.4 per turn. Hope this is of some assistance.

Remarkably little visible wear on the screw, but significant wear on the bronze nut.

Rebo.

Hi Rebo,
What you have is a standard imperial spindle that I guess was supplied as an interum measure by hercus at the start of the metric era, using a dial of the type you mention saved re-tooling and allowed them to use the existing imperial spindles which generated 100thou per rev or 2.54mm. I have come across several owners with a similar arrangement. As far as I can tell there are 3 versions of the spindle and dial, 1 is like yours a 10tpi acme, another version (which appears to be the most numerous) also uses an acme thread which gives a result very close to 2mm per turn (1.96mm pitch) and the last, which I am not sure was supplied by Hercus gives an even 2.00mm per turn using a metric trapezoidal thread of 2mm pitch.
All 3 styles are in circulation so there is no right or wrong part, owners ordering new nuts need to know the exact pitch of their spindles down to 0.01mm.
Mal

> Anyone else tried metric dials on imperial lathes ?

John, many lathe manufacturers did this sort of shortcuts. It is a pain to use, because there is a cumulative error that adds up over several handwheel revolutions. There are four things you can do:

- live with it as is, and take a few more control measurements as the job progresses to compensate for the error

- make or buy metric leadscrews and nuts (you may try to sell the imperial ones on eBay to the US if still in good condition)

- leave the leadrcrew and nuts and dials as is, but add dial indicators to get a correct reading. Instead of (old school) dial indicators, you can also modify these cheap digital chinese calipers to mount permanently on your lathe (next time Aldi has them, buy a few as they are ridiculously cheap).

- leave the leadrcrew and nuts as is, toss the dials, and install a digital readout (DRO)insterad. This is the most expensive solution, but also the most useful. If you are a little bit iclined into things electronic, you could assemble a DRO yourself at very substantial savings. Have a look at this place: ShumaTech : ShumaTech
I made a total of four such DRO's over the past 8 years for lathe and mill, and am very very happy.

Chris

my 260 gives some where between 1.96 and 1.98 per revolution its an almost new old stock apron has only had very minimal use
john

Hi Pipeclay,

The serial number is C7852, which according to one of the lists posted on the Forum some time ago makes it circa 1961. Re-measured as imperial and closely examining the profile suggests that you are correct - it is 7/16 10 tpi Acme. Regards, Rebo

Originally Posted by allterrain50

Hi Rebo,
What you have is a standard imperial spindle that I guess was supplied as an interum measure by hercus at the start of the metric era, using a dial of the type you mention saved re-tooling and allowed them to use the existing imperial spindles which generated 100thou per rev or 2.54mm. I have come across several owners with a similar arrangement. As far as I can tell there are 3 versions of the spindle and dial, 1 is like yours a 10tpi acme, another version (which appears to be the most numerous) also uses an acme thread which gives a result very close to 2mm per turn (1.96mm pitch) and the last, which I am not sure was supplied by Hercus gives an even 2.00mm per turn using a metric trapezoidal thread of 2mm pitch.
All 3 styles are in circulation so there is no right or wrong part, owners ordering new nuts need to know the exact pitch of their spindles down to 0.01mm.
Mal

Hi Mal,
Thanks for the information. I have re-measured as imperial, and it is 7/16 x 10 tpi acme. Theoretically, therefore, I could install a "new" imperial nut and screw and retain my current dials, thereby eliminating the wear related backlash problem. Serial number of the lathe is C7852, and history is unknown. Regards, Rebo.

Originally Posted by cba_melbourne

> Anyone else tried metric dials on imperial lathes ?

John, many lathe manufacturers did this sort of shortcuts. It is a pain to use, because there is a cumulative error that adds up over several handwheel revolutions. There are four things you can do:

- live with it as is, and take a few more control measurements as the job progresses to compensate for the error

- make or buy metric leadscrews and nuts (you may try to sell the imperial ones on eBay to the US if still in good condition)

- leave the leadrcrew and nuts and dials as is, but add dial indicators to get a correct reading. Instead of (old school) dial indicators, you can also modify these cheap digital chinese calipers to mount permanently on your lathe (next time Aldi has them, buy a few as they are ridiculously cheap).

- leave the leadrcrew and nuts as is, toss the dials, and install a digital readout (DRO)insterad. This is the most expensive solution, but also the most useful. If you are a little bit iclined into things electronic, you could assemble a DRO yourself at very substantial savings. Have a look at this place: ShumaTech : ShumaTech
I made a total of four such DRO's over the past 8 years for lathe and mill, and am very very happy.

Chris

hi my 9"c is has metric dials on an imperial lathe. at least i think it is imperial.