I recently took them off to mount that monolithic piece of aluminum for
the college race team guy's gear box, and now I need to put them back on.
Is there a reason pins would be a bad idea?-a Hold down force is against
the flat of the table, not the side of the pin.-a I have plenty of pins
on hand, and the diameter tolerance is quite good.-a The length tends to
be 10 thou over, but the diameter is usually 0.000 - +.0002.-a Far better than I can position the holes.-a I figure I would pull them gently
against the side of the t-slot, lightly clamp down the vises, and then
bump them as needed for position.-a I'm not even against taking a light
cut along the steps I machined in the jaws if necessary after the vises
are tightened down.
Is there a reason pins would be a bad idea?
"Bob La Londe"-a wrote in message news:10vfo00$15ec6$1@dont-email.me...
Is there a reason pins would be a bad idea?
My Microcentric pie jaw lathe chuck uses pairs of 1/8" dowel pins to
locate the top jaws, with one clamping screw between them. Kinematically they should be as good as the machining of the tee slots, which you
could check for tight or loose spots with an adjustable parallel. You
aren't roughing out iron castings which might shift a vise secured to
the oily table only by bolt tension.
The RF-31 that replaced a worn-out drill press for the company had tee
slots that weren't quite parallel to table travel, and the large drill
press vise (18 vs 80 Lbs) I ordered for it had no slot underneath. I
milled a close fitted key at home and found with it that the table slot
had loose and tight places, which I filed to an even slight drag all over.
The quill on the RF-31 shifted when clamped, limiting it to ~0.005"
vertical adjustment. The Clausing can do 0.0005".
To align the vise jaws and X axis I clamped the key in its tee slot and milled the top slightly narrower, thus parallel to table travel, closed
the vise on it upside down and milled the matching press-fit slot in the bottom.
I set the ram position to make the largest collet-sized endmill slightly clear behind the rear vise jaw with the table fully forward. Thus the
work can be lifted out or the table moved rapidly.
On 5/30/2026 6:12 PM, Jim Wilkins wrote:
"Bob La Londe"-a wrote in message news:10vfo00$15ec6$1@dont-email.me...
Is there a reason pins would be a bad idea?
My Microcentric pie jaw lathe chuck uses pairs of 1/8" dowel pins to
locate the top jaws, with one clamping screw between them.
Kinematically they should be as good as the machining of the tee
slots, which you could check for tight or loose spots with an
adjustable parallel. You aren't roughing out iron castings which might
shift a vise secured to the oily table only by bolt tension.
The RF-31 that replaced a worn-out drill press for the company had tee
slots that weren't quite parallel to table travel, and the large drill
press vise (18 vs 80 Lbs) I ordered for it had no slot underneath. I
milled a close fitted key at home and found with it that the table
slot had loose and tight places, which I filed to an even slight drag
all over.
The quill on the RF-31 shifted when clamped, limiting it to ~0.005"
vertical adjustment. The Clausing can do 0.0005".
To align the vise jaws and X axis I clamped the key in its tee slot
and milled the top slightly narrower, thus parallel to table travel,
closed the vise on it upside down and milled the matching press-fit
slot in the bottom.
I set the ram position to make the largest collet-sized endmill
slightly clear behind the rear vise jaw with the table fully forward.
Thus the work can be lifted out or the table moved rapidly.
These are going on a CNC mill, so a rapid to full Z height or any other
safe clearance area is as fast as I can turn the MPG, or already done
when I walk up if I add it to the end of the program, which I do.-a The
M30 macro at the end of every program does a G53 to Z zero at full
speed, along with a redundant spindle off and coolant off command.
I was getting a little cocky.-a Everything was just working the last few days.-a Turning parts, machining.-a CNC programs.-a Just working.-a The first of the two vises went perfectly.-a On the second one I hit hard
spots and ruined the tip on every screw machine length split point
letter D drill in the shop except those in tool holders on CNC machines.
-aIts one of those I buy in multiples because it gets used all the time.
-aI didn't want to drill the pin hole with a hand grind, because I
wanted better accuracy than MY hand grinds can give you.-a I have two
empty holes in the second vise because of "problems."-a Finally I ran
across a .248 reamer I forgot I own.-a I broke the surface and cleaned up the hole by pecking donw 1/8 inch with an end mill, then I spotted with
a center drill, and then I drilled it with a.242 (letter C) drill.-a From what I was reading .007 was to much maybe for an HSS .249 reamer so I
risked the .248 reamer. finished with the .249 reamer, and set the pin.
After the first vise went so easily the second one nearly whooped me.
Now to order a box of new split point letter D drills. LOL.
"Bob La Londe" wrote in message news:10vg3ai$18310$1@dont-email.me...
....
I made a tool that locks in a 1/2" hole by screwing in a 1/4-28 bolt but it may not scale down in length and be too much work for your welding table pins.
It's a puller for a 1/2" bronze bushing in a blind hole in the end plate of a hydraulic pump. The working part is a sleeve with a raised rim on the end that catches the bushing. Lengthwise slits ending in drilled holes let it compress to fit in. The area of the holes was bored larger than 1/4" to flex, by cut and try to balance strength and stiffness; the first try was too weak.
The area beyond the holes was tapped 1/4-28 with a taper tap run only deep enough that the fingers expand to grip the bushing when the bolt passes through. This was too fussy for multiple parts, leaving the OD large and turning it down to an interference fit in the hole with the bolt in place might be easier. A smaller stub on the end compressed in a collet would remove thread clearance and hold the split fingers securely.
The bolt extracts the bushing. The end of the bolt was also tapered to start in the compressed threads. I didn't spring temper it and multiple cycles might have cracked it.
It was a lot of work to save a bushing I could have drilled out and wouldn't reinstall if I could successfully fit a new one, though it avoided risk to the end plate. Its most valuable use has been as a pocketable example of my custom tool making ability at job interviews.
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