On the craftex cx601 same style as the grizzly g0704 or pm25 or pm30 when i try to lower the quill with the fine feed engaged it kinda works sometimes and then other times does not. The worm and wheel look ok to me. If I hold the brass gear in my hand and turn the handle it will slip a bit but there is definitely resistance. Any ideas?
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Fine feed slipping
- Thread starter Thriller
- Start date
OK, a SWAG here. Looking at photos of the G0704 on Grizzly's website, it appears to have the same basic Z feed mechanism as my G1007 (RF-30 clone). There's a fine feed crank, a drillpress-like spider with 3 arms, a knob to couple the fine feed to the spider, and somewhere else a Z spindle lock. Here's what they look like on my Grizzle. Note that I only have one (moveable) arm on the spider:
When I fully unscrew and remove the fine feed coupling knob (furthest right in the photo), the spider assembly slides off. The fine feed gearing rotates the outer sleeve, which can rotate freely with respect to the inner shaft. The shaft (deeper inside) contains the pinion that runs the spindle up and down. The spider is rotationally locked to the shaft with a key. The fine feed sleeve and the spider are pulled together when the coupling knob is tightened. So tightening this knob pulls the conical faces of the spider and the sleeve together, rotationally locking them together by friction. Motion of the fine feed knob is thus transmitted to the pinion and thereby to the rack on the spindle.
If these conical faces are slippery from oil or foreign material, the coupling will be inefficient. Way back when, I once cleaned both surfaceswith solvent, locked the spindle, and cranked the spider around a few times with the lock knob just slightly tightened. This got rid of some high spots on the conical surfaces and did a lot to improve the fine feed. More recently, I very lightly sand blasted both of the conical surfaces with super-fine grit. I now get very positive engagement of the fine feed when I need it.
Hope this helps!
When I fully unscrew and remove the fine feed coupling knob (furthest right in the photo), the spider assembly slides off. The fine feed gearing rotates the outer sleeve, which can rotate freely with respect to the inner shaft. The shaft (deeper inside) contains the pinion that runs the spindle up and down. The spider is rotationally locked to the shaft with a key. The fine feed sleeve and the spider are pulled together when the coupling knob is tightened. So tightening this knob pulls the conical faces of the spider and the sleeve together, rotationally locking them together by friction. Motion of the fine feed knob is thus transmitted to the pinion and thereby to the rack on the spindle.
If these conical faces are slippery from oil or foreign material, the coupling will be inefficient. Way back when, I once cleaned both surfaceswith solvent, locked the spindle, and cranked the spider around a few times with the lock knob just slightly tightened. This got rid of some high spots on the conical surfaces and did a lot to improve the fine feed. More recently, I very lightly sand blasted both of the conical surfaces with super-fine grit. I now get very positive engagement of the fine feed when I need it.
Hope this helps!