I've been letting a couple of the guys from the college BAJA SAE team machine some parts in my shop the last few days.
I had an idea to make a useful tool for bottom clamping large parts to
allow almost full access.-a A more flexible version of the edge clamping system I use for mold making fixture plates.-a Of course I had to make
it... all on the manual South Bend mill.-a Not one bit of CNC involved. I made the bulk of it from 4140.-a Then I tapped 16 holes in 4140 without breaking a single tap.-a I powered tapped them... with a hand tap.
As I was tapping the 15th and 16th hole I was already thinking about
coming to the group to brag about it, and knowing I should shut down
that way of think, because if I didn't I would surely break a tap off in
the last hole.
Two of the guys who were babysitting the CNC mill they were using walked
out of the CNC machine room as I was lining up on hole 16 and I asked
them, "Are you ready to see me break a tap off in a hole?"
Of course when they found out what I was making they wanted it for that freaking monolith of aluminum they are turning into mostly chips and a
gear case.-a Just coincidentally it would be a hundred times better than
the strap clamps they are using now.
On 4/29/2026 7:28 PM, Bob La Londe wrote:
I've been letting a couple of the guys from the college BAJA SAE team
machine some parts in my shop the last few days.
I had an idea to make a useful tool for bottom clamping large parts to
allow almost full access.-a A more flexible version of the edge
clamping system I use for mold making fixture plates.-a Of course I had
to make it... all on the manual South Bend mill.-a Not one bit of CNC
involved. I made the bulk of it from 4140.-a Then I tapped 16 holes in
4140 without breaking a single tap.-a I powered tapped them... with a
hand tap.
As I was tapping the 15th and 16th hole I was already thinking about
coming to the group to brag about it, and knowing I should shut down
that way of think, because if I didn't I would surely break a tap off
in the last hole.
Two of the guys who were babysitting the CNC mill they were using
walked out of the CNC machine room as I was lining up on hole 16 and I
asked them, "Are you ready to see me break a tap off in a hole?"
Of course when they found out what I was making they wanted it for
that freaking monolith of aluminum they are turning into mostly chips
and a gear case.-a Just coincidentally it would be a hundred times
better than the strap clamps they are using now.
P.S.-a I cheated and went with only 60% thread form.
On 4/29/2026 7:28 PM, Bob La Londe wrote:
Then I tapped 16 holes in 4140 without breaking a single tap. I powered
tapped them... with a hand tap.
"Snag"-a wrote in message news:10sulch$2nl4i$1@dont-email.me...
On 4/29/2026 9:30 PM, Bob La Londe wrote:
On 4/29/2026 7:28 PM, Bob La Londe wrote:
Then I tapped 16 holes in 4140 without breaking a single tap.-a I
powered tapped them... with a hand tap.
-----------------------------
That's a mark of an experienced professional.
I go the taper, plug, bottoming route for difficult ones, like holes in grade 5 and 8 bolts.
When building custom machinery we had to tap the pre-punched mounting
rails in shop-made 12 gauge steel relay racks. I used a Milwaukee drill freehand and retired the 10-32 taps after each 1000 holes.
Now they are called server racks. The hole pattern spacing alternates between 1/2" and 5/8" apart, lots of holes per rack. https://www.budind.com/racks-cabinets-relay-racks/?
On 4/30/2026 4:52 AM, Jim Wilkins wrote:
"Snag"-a wrote in message news:10sulch$2nl4i$1@dont-email.me...
On 4/29/2026 9:30 PM, Bob La Londe wrote:
On 4/29/2026 7:28 PM, Bob La Londe wrote:
Then I tapped 16 holes in 4140 without breaking a single tap.-a I
powered tapped them... with a hand tap.
-----------------------------
That's a mark of an experienced professional.
I go the taper, plug, bottoming route for difficult ones, like holes
in grade 5 and 8 bolts.
When building custom machinery we had to tap the pre-punched mounting
rails in shop-made 12 gauge steel relay racks. I used a Milwaukee
drill freehand and retired the 10-32 taps after each 1000 holes.
Now they are called server racks. The hole pattern spacing alternates
between 1/2" and 5/8" apart, lots of holes per rack.
https://www.budind.com/racks-cabinets-relay-racks/?
I used, worked on, and installed a lot of 19 inch equipment racks when
I was contracting.-a I've got an "expensive cabinet/rack sitting
outside rusting right now.
I used a Milwaukee drill freehand and retired the 10-32 taps after each
1000 holes.
I've been letting a couple of the guys from the college BAJA SAE team machine some parts in my shop the last few days.
I had an idea to make a useful tool for bottom clamping large parts to
allow almost full access.-a A more flexible version of the edge clamping system I use for mold making fixture plates.-a Of course I had to make
it... all on the manual South Bend mill.-a Not one bit of CNC involved. I made the bulk of it from 4140.-a Then I tapped 16 holes in 4140 without breaking a single tap.-a I powered tapped them... with a hand tap.
As I was tapping the 15th and 16th hole I was already thinking about
coming to the group to brag about it, and knowing I should shut down
that way of think, because if I didn't I would surely break a tap off in
the last hole.
Two of the guys who were babysitting the CNC mill they were using walked
out of the CNC machine room as I was lining up on hole 16 and I asked
them, "Are you ready to see me break a tap off in a hole?"
Of course when they found out what I was making they wanted it for that freaking monolith of aluminum they are turning into mostly chips and a
gear case.-a Just coincidentally it would be a hundred times better than
the strap clamps they are using now.
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