Thread: Butchered topslide Hercus 9"

I've had this 9" model C for 38 years and have only ever done light work with it. The graunched top slide is as I bought it and I assume it met its fate in a schoolroom workshop when chuck met top slide and chuck won.
I now find that as I use the parting tool more I am getting movement between toolholder and top slide and I am breaking parting tips during light or heavy use. My presumption is the loss of load bearing area on the top slide is contributing to the tool holder instability. I also understand parting off can be a dark art
Has anyone had one of these slides satisfactorily repaired by welding/brazing or any other method, or is it a replacement from somewhere
Advice would be appreciated
AlanMcl

Hi Alan.

I recognise that sort of damage. Here is my ex-school compound slide:
IMG_1368.jpg IMG_0084.jpg



I don't think your slide's damage will impact cutting or parting very much.


1) If you have the standard "lantern" toolpost, its clamping area is a disc that is well away from the damaged edge:
Screen Shot 2021-11-07 at 8.39.08 pm.jpg

2) If you have a Hercus square 4way toolpost, or a newer QCTP (like Swiss Multi*), it is a larger clamping base. While that might mean the base is over the damaged edge, it is bigger in the other directions also, which means more/stronger clamping.



I'm not very good at parting.
Mostly because my parting tool is tiny and flexible (MGMN200 inserts in a MGEHR1212-2 holder), but also because I am usually trying to part steel on a lathe that isn't quite rigid enough. (narrow compound slide, narrow cross slide, light weight carriage)



My suggestions;

A) Grab a large flat 2nd cut file, or smooth file, and gently file across the top of the compound slide, to make sure there are no high spots.

B) Always make everything as rigid as possible. Check your saddle gib isn't loose (the strap across the back of the carriage that clamps onto the back of the bed). If the compound is wound toward the chuck, wind it back, so the toolpost is close to the middle of the cross slide. Lock the saddle. If possible, tighten the gib screws, or use a clamp to stop the compound from rattling in its feed screw and dovetail.

C) If your parting tool is juddering/grabbing/twisting;

C1) Make sure your parting tool has clearance. Use a micrometer to make sure the nose width isn't smaller than the slot being cut further back along the tool. Here is a nice diagram from Parting Off on Mini Lathes and Bearing Choices
Parting_Tool.jpg

C2) Make sure your parting tool is perpendicular to the spindle centre.

C3) Try making clearance as you cut. Go in by 2mm, pull back, go left a little, go in by 4 mm, pull back, go right a little, go in my 6mm, et c.

D) For gummy materials (Copper, most Aluminiums), try coolant, oil, talcum powder




You can maybe get another compound top slide casting from Mal:
https://australianmetalworkinghobbyi...ound+top+slide

but unless it is cracked, I wouldn't bother!

Originally Posted by nigelpearson

Hi Alan.

I recognise that sort of damage. Here is my ex-school compound slide:
IMG_1368.jpg IMG_0084.jpg



I don't think your slide's damage will impact cutting or parting very much.


1) If you have the standard "lantern" toolpost, its clamping area is a disc that is well away from the damaged edge:
Screen Shot 2021-11-07 at 8.39.08 pm.jpg

2) If you have a Hercus square 4way toolpost, or a newer QCTP (like Swiss Multi*), it is a larger clamping base. While that might mean the base is over the damaged edge, it is bigger in the other directions also, which means more/stronger clamping.



I'm not very good at parting.
Mostly because my parting tool is tiny and flexible (MGMN200 inserts in a MGEHR1212-2 holder), but also because I am usually trying to part steel on a lathe that isn't quite rigid enough. (narrow compound slide, narrow cross slide, light weight carriage)



My suggestions;

A) Grab a large flat 2nd cut file, or smooth file, and gently file across the top of the compound slide, to make sure there are no high spots.

B) Always make everything as rigid as possible. Check your saddle gib isn't loose (the strap across the back of the carriage that clamps onto the back of the bed). If the compound is wound toward the chuck, wind it back, so the toolpost is close to the middle of the cross slide. Lock the saddle. If possible, tighten the gib screws, or use a clamp to stop the compound from rattling in its feed screw and dovetail.

C) If your parting tool is juddering/grabbing/twisting;

C1) Make sure your parting tool has clearance. Use a micrometer to make sure the nose width isn't smaller than the slot being cut further back along the tool. Here is a nice diagram from Parting Off on Mini Lathes and Bearing Choices
Parting_Tool.jpg

C2) Make sure your parting tool is perpendicular to the spindle centre.

C3) Try making clearance as you cut. Go in by 2mm, pull back, go left a little, go in by 4 mm, pull back, go right a little, go in my 6mm, et c.

D) For gummy materials (Copper, most Aluminiums), try coolant, oil, talcum powder




You can maybe get another compound top slide casting from Mal:
https://australianmetalworkinghobbyi...ound+top+slide

but unless it is cracked, I wouldn't bother!

Some years back I installed an extended cross slide to my Hercus 260 lathe & use an inverted rear toolpost for parting off.
This is a very solid & convenient unit as it stays in position clamped all the time, & does not get in the way of conventional turning using the front conventional toolpost.
So all good !
Bruce

I did some parting off on 9"AR today with a similar tool, but in brazed carbide in a shop made tool holder. Low speed and feed and it went very well. These little lathes are quite something.