Cannot reverse if half nut engaged

[Peter Housyon]

EMCO compact 8.
If I try to reverse the spindle with the half nut engaged, the "quadrant" holding the change gears is forced out of engagement by the spindle gear (which is rotating backwards of course). The "quadrant" is only held by a pinch bolt at the collar around the end of the lead screw. I am afraid of shearing off the cap screw-pinch bolt that is supposed to secure the quadrant.
Help !

 

[markba633csi]

Probably a weak point in the design, but too much friction in the carriage travel might be a contributing factor. You could add a stay/strut to the quadrant to give it more support possibly

 

[wa5cab]

Peter,

This Forum is not the appropriate one in which to ask a question of this nature. The Site Access Problems Forum, as the name implies, is for issues with the site, including issues with getting access to the site.to begin with. Probably the appropriate Forum would be

BOXFORD, MYFORD, DENFORD VICEROY, EMCO & UNIMAT MACHINES .​

However, before moving your question, I will comment that the most likely culprit is wear on the cylindrical part that the banjo clamps to or that the split hole for clamping has worn and taken a set (i.e., bent) or both so that it no longer gets tight. To correct, either replace the worn part or dismount and strip the banjo and use a strip sander with the back stop moved out of the way to open up the gap. When installed and tightened , you should still be able toi see light through the gap.

 

[Peter Housyon]

Peter,

This Forum is not the appropriate one in which to ask a question of this nature. The Site Access Problems Forum, as the name implies, is for issues with the site, including issues with getting access to the site.to begin with. Probably the appropriate Forum would be

BOXFORD, MYFORD, DENFORD VICEROY, EMCO & UNIMAT MACHINES .​

However, before moving your question, I will comment that the most likely culprit is wear on the cylindrical part that the banjo clamps to or that the split hole for clamping has worn and taken a set (i.e., bent) or both so that it no longer gets tight. To correct, either replace the worn part or dismount and strip the banjo and use a strip sander with the back stop moved out of the way to open up the gap. When installed and tightened , you should still be able toi see light through the gap.

The "banjo" clamp seems tight enough as long as the spindle is not running in reverse. It is not closing completely. I removed the rectangular "covermount" to allow me to move the clamp further right around the leadscrew collar but that did not help. Could it be too much drag on the half nut ?

 

[kolbroshop]

I had similar case once upon a time. Dismantle your banjo, clean and grease gear axles. Tighten them, and gears must spin freely(if they do not spin freely, then maybe you have missing or worn washers. . And when meshing gears, leave room for backlash, don't mesh them too tightly. I am doing it by a feeling, but you can use sheet of office paper, so you have the needed distance...

 

[wa5cab]

First, on some machines (Atlas for example) gear teeth get grease. Axles and round spacers get oil, SAE 20 ND to be specific. But use what Emco calls for. However, unless each axle has a grease fitting, the Emco instructions will probably call for oil. The only way in which to get grease in to the bearing surfaces is either dismantle for each session of with some sort of a grease gun fitting.

However, this problem apparently doesn't happen when Forward, meaning towards the headstock, is selected. So something must happen differently when Reverse is selected. Figure out what and why and correct that.