- Joined
- Sep 8, 2019
- Messages
- 4,392
I saw this coming because one of these bolts was almost entirely stripped last week; I have always had a habit of overtightening hardware. In machining school, they said "Tight is good. Too tight is f***ed".
Today I was facing some hard steel (ER70S-6, only a .005" DOC) and the freshly sharpened 3/8" HSS facing tool was pushed back by the workpiece. This in turn rotated the AXA toolpost. The toolpost was rigidly mounted to the compound so the entire compound assembly rotated on the cross slide.
There is a circular scuff mark on the (precision ground flat) top of the cross slide where the base of the compound assembly rotated. The compound was oriented as it is in the photos (i.e. perpindicular to the spindle) so the workpiece had maximum leverage in which to exert force on the compound assembly.
I took it all apart, hoping to bypass the compound and mount the toolpost directly to the cross slide. I did not see a way to do that; I would be interested in doing that sometimes because I rarely use the compound.
Anyway, I had already ordered a selection of appropriately sized T slot nuts which are on their way (photo below). My plan is to use Grade 12.9 (metric) bolts to use in place of the aforementioned stripped bolts. I will need to reduce the height of the bolt head so that it will fit under the compound upon rotation (one needs to use a cone wrench to tighten these).
Any thoughts about this? Maybe I should use a torque wrench the first time so that I can get a feel for the proper torque spec? I was giving it well over 60 ft. lbs. When I need a torque spec, I just Google the spec for that sized (and material of) hardware. The bolt will be an M8 or M10; I have to wait for my selection of T slot nuts to arrive in order to see if it is an M8 or M10.
Today I was facing some hard steel (ER70S-6, only a .005" DOC) and the freshly sharpened 3/8" HSS facing tool was pushed back by the workpiece. This in turn rotated the AXA toolpost. The toolpost was rigidly mounted to the compound so the entire compound assembly rotated on the cross slide.
There is a circular scuff mark on the (precision ground flat) top of the cross slide where the base of the compound assembly rotated. The compound was oriented as it is in the photos (i.e. perpindicular to the spindle) so the workpiece had maximum leverage in which to exert force on the compound assembly.
I took it all apart, hoping to bypass the compound and mount the toolpost directly to the cross slide. I did not see a way to do that; I would be interested in doing that sometimes because I rarely use the compound.
Anyway, I had already ordered a selection of appropriately sized T slot nuts which are on their way (photo below). My plan is to use Grade 12.9 (metric) bolts to use in place of the aforementioned stripped bolts. I will need to reduce the height of the bolt head so that it will fit under the compound upon rotation (one needs to use a cone wrench to tighten these).
Any thoughts about this? Maybe I should use a torque wrench the first time so that I can get a feel for the proper torque spec? I was giving it well over 60 ft. lbs. When I need a torque spec, I just Google the spec for that sized (and material of) hardware. The bolt will be an M8 or M10; I have to wait for my selection of T slot nuts to arrive in order to see if it is an M8 or M10.