I am installing a DRO on my horizontal mill. Unfortunately, there are three locations that require drilling (hopefully) blind holes in castings which hold an oil bath for a gear train (one hole in the knee, two in the column for mounting the display). I don't have good access to the inside of these castings, even if I empty the oil and take off the inspection plates/covers.
I purchased a low-cost ultrasonic tester (offshore GM100) to see if this would work. The device does surprisingly well on the few pieces of steel and aluminum I tested. Cast iron, however, seems to not work with this at all. Even my angle plates with nice flat surfaces give erroneously small thickness readings (ie, reads 4mm, when the angle plate is 23mm thick).
Any suggestions?
ETA: Figured I would add based on the responses so far:
My hope was to use the ultrasonic gauge to find a places where I could drill deep enough to tap without running through into the oil bath cavity. I am NOT concerned with oil leaking from these threads (they are all well above the oil level). My main concern is drilling through then spilling drill/tapping chips in the oil that I will not be able to retrieve.
The one hole in the knee is far more concerning that the column as the scale HAS to mount there. However, the scale uses a 4mm screw. I hoped there would be a place where I could drill 8mm deep, use a bottoming tap, an have plenty of threads of the screw to hold the scale (not much weight).
As for the column, I could likely find another location to mount the display. However, if I had a way to determine thickness, it would be cleanest to mount it there knowing I had the depth on the casting. (these would be drilled for 6mm screws)
I purchased a low-cost ultrasonic tester (offshore GM100) to see if this would work. The device does surprisingly well on the few pieces of steel and aluminum I tested. Cast iron, however, seems to not work with this at all. Even my angle plates with nice flat surfaces give erroneously small thickness readings (ie, reads 4mm, when the angle plate is 23mm thick).
Any suggestions?
ETA: Figured I would add based on the responses so far:
My hope was to use the ultrasonic gauge to find a places where I could drill deep enough to tap without running through into the oil bath cavity. I am NOT concerned with oil leaking from these threads (they are all well above the oil level). My main concern is drilling through then spilling drill/tapping chips in the oil that I will not be able to retrieve.
The one hole in the knee is far more concerning that the column as the scale HAS to mount there. However, the scale uses a 4mm screw. I hoped there would be a place where I could drill 8mm deep, use a bottoming tap, an have plenty of threads of the screw to hold the scale (not much weight).
As for the column, I could likely find another location to mount the display. However, if I had a way to determine thickness, it would be cleanest to mount it there knowing I had the depth on the casting. (these would be drilled for 6mm screws)
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