|
Thanks Rob.? Yeah, the issue I have is with the holes along the bottom of those boards for the bus.? Everywhere else has been mostly fine.? But the bit sort of goes through them, and then they wrap themselves around the drill bit and pull off. ? I’ve got pics of the board I’ve made and the artwork: http://bradhodge.ca/blog/?cat=27 ? The bit I am using is a Dremel 1/32” (?) bit.. it comes in a pack of 6 of them, it’s the very smallest one.? Seems pretty sharp to me but maybe not.? I’ve tried different speed settings with the dremel to see if that helps but so far no dice. ? That’s cool re your CP/M system – I just bought a Ferguson Big Board II that was setup that way also.? Unfortunately the previous owner decided to toss the case, keyboard and floppies.? Fortunately they saved the board. ? Brad ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Rob via Groups.Io
Sent: Monday, September 24, 2018 9:27 PM
To: [email protected]
Subject: Re: [homebrewpcbs] Small pads breaking off while drilling Jon Titus’ Mark-8.? Found some pictures of Jon Titus’ Mark-8.
My first computer was a CP/M 8 user system with two 8 inch floppies.
If you are drilling those really tight IC pads you might need sharper drill bits. On 09/25/2018 12:17 AM, Rob via Groups.Io wrote: I use a #60 drill bit and have found that a dull bit makes a mess or breaks.
I like a larger trace and landing size for my home brewed circuits.
I always make a dough nut or cross shape in the artwork so the drill bit
will waltz into the PCB without binding too much with the copper.
?
I often get dozens of PCBs out of one #60? drill bit before it breaks.
I used to use smaller drill bits ..#70.. but concluded that the smaller
hole was not worth breaking 2 bits on each PCB.
?
On 09/24/2018 11:34 PM, unclefalter via Groups.Io wrote: Hi guys, ? So I’m working on a replica of Jon Titus’ Mark-8.? I’ve made a set of boards using his plans, and also using some 1973 vintage blank PCB stock to etch them on.? So far so good, but I’m running into a problem along the bottom of the board – there are a series of very small holes/pads that have to be drilled through for the bus.? I’m using a dremel with a 1/32” bit and I had the foresight to put holes in each of the pads.? Regardless, the drill is simply wrapping them around the shaft and pulling them off the board.? Not sure what I can do here.. any recommendations?? Should I have done the drilling before I etched? ? Brad ?
?
?
|
I suppose the? tinning of the edge connector pads maker it tough for the drill not to damage the entire pad. few thoughts. ?drill speed. ?a new bit. use cleaning tool like de-solder wick to remove excess lead on those pad. try a smaller dia bit first, then increase to standard dia
perhaps the pads could have been little more larger outer dia. ( late thinking as they were already made, we need to manage)
regards sarma vu3zmv
On Tue, Sep 25, 2018 at 10:24 AM unclefalter via Groups.Io <unclefalter= [email protected]> wrote: Thanks Rob.? Yeah, the issue I have is with the holes along the bottom of those boards for the bus.? Everywhere else has been mostly fine.? But the bit sort of goes through them, and then they wrap themselves around the drill bit and pull off. ? I’ve got pics of the board I’ve made and the artwork: ? The bit I am using is a Dremel 1/32” (?) bit.. it comes in a pack of 6 of them, it’s the very smallest one.? Seems pretty sharp to me but maybe not.? I’ve tried different speed settings with the dremel to see if that helps but so far no dice. ? That’s cool re your CP/M system – I just bought a Ferguson Big Board II that was setup that way also.? Unfortunately the previous owner decided to toss the case, keyboard and floppies.? Fortunately they saved the board. ? Brad ? ? Found some pictures of Jon Titus’ Mark-8.
My first computer was a CP/M 8 user system with two 8 inch floppies.
If you are drilling those really tight IC pads you might need sharper drill bits. On 09/25/2018 12:17 AM, Rob via Groups.Io wrote: I use a #60 drill bit and have found that a dull bit makes a mess or breaks.
I like a larger trace and landing size for my home brewed circuits.
I always make a dough nut or cross shape in the artwork so the drill bit
will waltz into the PCB without binding too much with the copper.
?
I often get dozens of PCBs out of one #60? drill bit before it breaks.
I used to use smaller drill bits ..#70.. but concluded that the smaller
hole was not worth breaking 2 bits on each PCB.
?
On 09/24/2018 11:34 PM, unclefalter via Groups.Io wrote: Hi guys, ? So I’m working on a replica of Jon Titus’ Mark-8.? I’ve made a set of boards using his plans, and also using some 1973 vintage blank PCB stock to etch them on.? So far so good, but I’m running into a problem along the bottom of the board – there are a series of very small holes/pads that have to be drilled through for the bus.? I’m using a dremel with a 1/32” bit and I had the foresight to put holes in each of the pads.? Regardless, the drill is simply wrapping them around the shaft and pulling them off the board.? Not sure what I can do here.. any recommendations?? Should I have done the drilling before I etched? ? Brad ?
?
?
|
1/32" is 0.8mm near enough
First, try a fresh unused brand new bit, tearing holes and making a mess of it is usually the sign of a bit that's done a few too many holes, FR4 will kill an HSS bit very very quickly, usually I start drilling a board with a fresh bit and the last few holes are getting pretty hairy and I'm usually kicking myself for not changing the bit again halfway through.??
Bits are cheap on aliexpress etc search for 0.8mm HSS
You also want it short, mount it as far into the chuck as you can, I've gone so far as to cut the end off the shank so it can go in further, shorter bit less wobbly.
Failing that, get a carbide drill bit, 0.8mm again not too expensive on aliexpress etc, just be aware that they are fragile, but it is certainly possible to use them in a dremel as long as you have a reasonably steady hand.
On Tue, Sep 25, 2018 at 4:54 PM, unclefalter via Groups.Io <unclefalter@...> wrote: Thanks Rob.? Yeah, the issue I have is with the holes along the bottom of those boards for the bus.? Everywhere else has been mostly fine.? But the bit sort of goes through them, and then they wrap themselves around the drill bit and pull off. ? I’ve got pics of the board I’ve made and the artwork: ? The bit I am using is a Dremel 1/32” (?) bit.. it comes in a pack of 6 of them, it’s the very smallest one.? Seems pretty sharp to me but maybe not.? I’ve tried different speed settings with the dremel to see if that helps but so far no dice. ? That’s cool re your CP/M system – I just bought a Ferguson Big Board II that was setup that way also.? Unfortunately the previous owner decided to toss the case, keyboard and floppies.? Fortunately they saved the board. ? Brad ? ? Found some pictures of Jon Titus’ Mark-8.
My first computer was a CP/M 8 user system with two 8 inch floppies.
If you are drilling those really tight IC pads you might need sharper drill bits. On 09/25/2018 12:17 AM, Rob via Groups.Io wrote: I use a #60 drill bit and have found that a dull bit makes a mess or breaks.
I like a larger trace and landing size for my home brewed circuits.
I always make a dough nut or cross shape in the artwork so the drill bit
will waltz into the PCB without binding too much with the copper.
?
I often get dozens of PCBs out of one #60? drill bit before it breaks.
I used to use smaller drill bits ..#70.. but concluded that the smaller
hole was not worth breaking 2 bits on each PCB.
?
On 09/24/2018 11:34 PM, unclefalter via Groups.Io wrote: Hi guys, ? So I’m working on a replica of Jon Titus’ Mark-8.? I’ve made a set of boards using his plans, and also using some 1973 vintage blank PCB stock to etch them on.? So far so good, but I’m running into a problem along the bottom of the board – there are a series of very small holes/pads that have to be drilled through for the bus.? I’m using a dremel with a 1/32” bit and I had the foresight to put holes in each of the pads.? Regardless, the drill is simply wrapping them around the shaft and pulling them off the board.? Not sure what I can do here.. any recommendations?? Should I have done the drilling before I etched? ? Brad ?
?
?
|
Carbide bits are pretty cheap (at least resharpened bits are) and
will be much sharper to start and will last much longer. They also
have a larger shank for the drill motor to grip. A carbide bit
will break if the drill motor is not extremely good; it needs to
have very little runout and absolutely no wobble.
High speed steel will dull very quickly in circuit board stock,
especially in glass-based (like FR4) but phenolic/paper stock is
surprisingly abrasive.
Donald.
--
*Plain Text* email -- it's an accessibility issue
() no proprietary attachments; no html mail
/\
On 25-Sep-2018 00:54, unclefalter via
Groups.Io wrote:
toggle quoted message
Show quoted text
Thanks Rob.?
Yeah, the issue I have is with the holes along the bottom of
those boards for the bus.? Everywhere else has been mostly
fine.? But the bit sort of goes through them, and then they
wrap themselves around the drill bit and pull off.
?
I’ve got pics
of the board I’ve made and the artwork:
?
The bit I am
using is a Dremel 1/32” (?) bit.. it comes in a pack of 6 of
them, it’s the very smallest one.? Seems pretty sharp to me
but maybe not.? I’ve tried different speed settings with the
dremel to see if that helps but so far no dice.
?
That’s cool re
your CP/M system – I just bought a Ferguson Big Board II
that was setup that way also.? Unfortunately the previous
owner decided to toss the case, keyboard and floppies.?
Fortunately they saved the board.
?
Brad
?
?
Found some
pictures of Jon Titus’ Mark-8.
My first computer was a CP/M 8 user system with two 8 inch
floppies.
If you are drilling those really tight IC pads you might need
sharper drill bits.
On 09/25/2018 12:17 AM, Rob via Groups.Io
wrote:
I use a #60 drill bit and have
found that a dull bit makes a mess or breaks.
I like a larger trace and landing size for my home brewed
circuits.
I always make a dough nut or cross shape in the artwork so
the drill bit
will waltz into the PCB without binding too much with the
copper.
?
I often get dozens of PCBs out of one #60? drill bit
before it breaks.
I used to use smaller drill bits ..#70.. but concluded
that the smaller
hole was not worth breaking 2 bits on each PCB.
?
On 09/24/2018 11:34 PM, unclefalter via
Groups.Io wrote:
Hi guys,
?
So I’m working on a replica of Jon
Titus’ Mark-8.? I’ve made a set of boards using his plans,
and also using some 1973 vintage blank PCB stock to etch
them on.? So far so good, but I’m running into a problem
along the bottom of the board – there are a series of very
small holes/pads that have to be drilled through for the
bus.? I’m using a dremel with a 1/32” bit and I had the
foresight to put holes in each of the pads.? Regardless,
the drill is simply wrapping them around the shaft and
pulling them off the board.? Not sure what I can do here..
any recommendations?? Should I have done the drilling
before I etched?
?
Brad
?
?
?
|
I stumbled onto your IRONCLAD toner transfer method.
I use the heavy metal method:
On 09/25/2018 12:54 AM, unclefalter via
Groups.Io wrote:
toggle quoted message
Show quoted text
Thanks Rob.?
Yeah, the issue I have is with the holes along the bottom of
those boards for the bus.? Everywhere else has been mostly
fine.? But the bit sort of goes through them, and then they
wrap themselves around the drill bit and pull off.
?
I’ve got pics
of the board I’ve made and the artwork:
?
The bit I am
using is a Dremel 1/32” (?) bit.. it comes in a pack of 6 of
them, it’s the very smallest one.? Seems pretty sharp to me
but maybe not.? I’ve tried different speed settings with the
dremel to see if that helps but so far no dice.
?
That’s cool re
your CP/M system – I just bought a Ferguson Big Board II
that was setup that way also.? Unfortunately the previous
owner decided to toss the case, keyboard and floppies.?
Fortunately they saved the board.
?
Brad
?
?
Found some
pictures of Jon Titus’ Mark-8.
My first computer was a CP/M 8 user system with two 8 inch
floppies.
If you are drilling those really tight IC pads you might need
sharper drill bits.
On 09/25/2018 12:17 AM, Rob via Groups.Io
wrote:
I use a #60 drill bit and have
found that a dull bit makes a mess or breaks.
I like a larger trace and landing size for my home brewed
circuits.
I always make a dough nut or cross shape in the artwork so
the drill bit
will waltz into the PCB without binding too much with the
copper.
?
I often get dozens of PCBs out of one #60? drill bit
before it breaks.
I used to use smaller drill bits ..#70.. but concluded
that the smaller
hole was not worth breaking 2 bits on each PCB.
?
On 09/24/2018 11:34 PM, unclefalter via
Groups.Io wrote:
Hi guys,
?
So I’m working on a replica of Jon
Titus’ Mark-8.? I’ve made a set of boards using his plans,
and also using some 1973 vintage blank PCB stock to etch
them on.? So far so good, but I’m running into a problem
along the bottom of the board – there are a series of very
small holes/pads that have to be drilled through for the
bus.? I’m using a dremel with a 1/32” bit and I had the
foresight to put holes in each of the pads.? Regardless,
the drill is simply wrapping them around the shaft and
pulling them off the board.? Not sure what I can do here..
any recommendations?? Should I have done the drilling
before I etched?
?
Brad
?
?
?
|
The bit I’m using is brand new, so I don’t think it’s a sharpness issue.? I had to buy a new one after my old one snapped while doing some other work.? I’m feeling like these pads are just too small in diameter, as mentioned.? I’m wondering if there is a smaller than 1/32” bit I could use to drill pilot holes first?? Going to take a lot longer unfortunately.? ? Another option might be to hand drill? ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of Donald H Locker
Sent: Tuesday, September 25, 2018 3:39 AM
To: [email protected]
Subject: Re: [homebrewpcbs] Small pads breaking off while drilling Jon Titus' Mark-8.? Carbide bits are pretty cheap (at least resharpened bits are) and will be much sharper to start and will last much longer. They also have a larger shank for the drill motor to grip. A carbide bit will break if the drill motor is not extremely good; it needs to have very little runout and absolutely no wobble. High speed steel will dull very quickly in circuit board stock, especially in glass-based (like FR4) but phenolic/paper stock is surprisingly abrasive. Donald.
-- *Plain Text* email -- it's an accessibility issue () no proprietary attachments; no html mail /\ On 25-Sep-2018 00:54, unclefalter via Groups.Io wrote: Thanks Rob.? Yeah, the issue I have is with the holes along the bottom of those boards for the bus.? Everywhere else has been mostly fine.? But the bit sort of goes through them, and then they wrap themselves around the drill bit and pull off. ? I’ve got pics of the board I’ve made and the artwork: ? The bit I am using is a Dremel 1/32” (?) bit.. it comes in a pack of 6 of them, it’s the very smallest one.? Seems pretty sharp to me but maybe not.? I’ve tried different speed settings with the dremel to see if that helps but so far no dice. ? That’s cool re your CP/M system – I just bought a Ferguson Big Board II that was setup that way also.? Unfortunately the previous owner decided to toss the case, keyboard and floppies.? Fortunately they saved the board. ? Brad ? ? Found some pictures of Jon Titus’ Mark-8.
My first computer was a CP/M 8 user system with two 8 inch floppies.
If you are drilling those really tight IC pads you might need sharper drill bits. On 09/25/2018 12:17 AM, Rob via Groups.Io wrote: I use a #60 drill bit and have found that a dull bit makes a mess or breaks.
I like a larger trace and landing size for my home brewed circuits.
I always make a dough nut or cross shape in the artwork so the drill bit
will waltz into the PCB without binding too much with the copper.
?
I often get dozens of PCBs out of one #60? drill bit before it breaks.
I used to use smaller drill bits ..#70.. but concluded that the smaller
hole was not worth breaking 2 bits on each PCB.
?
On 09/24/2018 11:34 PM, unclefalter via Groups.Io wrote: Hi guys, ? So I’m working on a replica of Jon Titus’ Mark-8.? I’ve made a set of boards using his plans, and also using some 1973 vintage blank PCB stock to etch them on.? So far so good, but I’m running into a problem along the bottom of the board – there are a series of very small holes/pads that have to be drilled through for the bus.? I’m using a dremel with a 1/32” bit and I had the foresight to put holes in each of the pads.? Regardless, the drill is simply wrapping them around the shaft and pulling them off the board.? Not sure what I can do here.. any recommendations?? Should I have done the drilling before I etched? ? Brad ?
?
?
?
|
Drill bits are available down to 0.3mm easily on Aliexpress etc.
On Thu, Sep 27, 2018 at 2:04 PM unclefalter via Groups.Io <unclefalter= [email protected]> wrote: The bit I’m using is brand new, so I don’t think it’s a sharpness issue.? I had to buy a new one after my old one snapped while doing some other work.? I’m feeling like these pads are just too small in diameter, as mentioned.? I’m wondering if there is a smaller than 1/32” bit I could use to drill pilot holes first?? Going to take a lot longer unfortunately.? ? Another option might be to hand drill? ? ? Carbide bits are pretty cheap (at least resharpened bits are) and will be much sharper to start and will last much longer. They also have a larger shank for the drill motor to grip. A carbide bit will break if the drill motor is not extremely good; it needs to have very little runout and absolutely no wobble. High speed steel will dull very quickly in circuit board stock, especially in glass-based (like FR4) but phenolic/paper stock is surprisingly abrasive. Donald.
-- *Plain Text* email -- it's an accessibility issue () no proprietary attachments; no html mail /\ On 25-Sep-2018 00:54, unclefalter via Groups.Io wrote: Thanks Rob.? Yeah, the issue I have is with the holes along the bottom of those boards for the bus.? Everywhere else has been mostly fine.? But the bit sort of goes through them, and then they wrap themselves around the drill bit and pull off. ? I’ve got pics of the board I’ve made and the artwork: ? The bit I am using is a Dremel 1/32” (?) bit.. it comes in a pack of 6 of them, it’s the very smallest one.? Seems pretty sharp to me but maybe not.? I’ve tried different speed settings with the dremel to see if that helps but so far no dice. ? That’s cool re your CP/M system – I just bought a Ferguson Big Board II that was setup that way also.? Unfortunately the previous owner decided to toss the case, keyboard and floppies.? Fortunately they saved the board. ? Brad ? ? Found some pictures of Jon Titus’ Mark-8.
My first computer was a CP/M 8 user system with two 8 inch floppies.
If you are drilling those really tight IC pads you might need sharper drill bits. On 09/25/2018 12:17 AM, Rob via Groups.Io wrote: I use a #60 drill bit and have found that a dull bit makes a mess or breaks.
I like a larger trace and landing size for my home brewed circuits.
I always make a dough nut or cross shape in the artwork so the drill bit
will waltz into the PCB without binding too much with the copper.
?
I often get dozens of PCBs out of one #60? drill bit before it breaks.
I used to use smaller drill bits ..#70.. but concluded that the smaller
hole was not worth breaking 2 bits on each PCB.
?
On 09/24/2018 11:34 PM, unclefalter via Groups.Io wrote: Hi guys, ? So I’m working on a replica of Jon Titus’ Mark-8.? I’ve made a set of boards using his plans, and also using some 1973 vintage blank PCB stock to etch them on.? So far so good, but I’m running into a problem along the bottom of the board – there are a series of very small holes/pads that have to be drilled through for the bus.? I’m using a dremel with a 1/32” bit and I had the foresight to put holes in each of the pads.? Regardless, the drill is simply wrapping them around the shaft and pulling them off the board.? Not sure what I can do here.. any recommendations?? Should I have done the drilling before I etched? ? Brad ?
?
?
?
|
Brad,
I seem to recall from my dark distant past that when drilling
stacks of boards, the bottom board was not copper clad at all, it
was aluminum. I was told that this was to protect the integrity of
the drill holes on the last board in the stack. The purpose was to
support the board and keep the drill bit from breaking out into
free space and lifting and tearing the bottom layer of the last
board. You might try tightly clamping the board to another board
and drilling through both. It would be better if that board was
not FR-4, but something less abrasive.
Sharp carbide drill bits are a must. I buy them from China on
ebay in packages of 10 of a size at a time. I buy several sizes.
It is wise to have several bits in stock, as they always seem to
break when you have many more holes to drill. Drilling by hand is
a non starter with carbide bits. They are guaranteed to break.
Harvey
On 9/26/2018 7:04 PM, unclefalter via
Groups.Io wrote:
toggle quoted message
Show quoted text
The bit I’m
using is brand new, so I don’t think it’s a sharpness
issue.? I had to buy a new one after my old one snapped
while doing some other work.? I’m feeling like these pads
are just too small in diameter, as mentioned.? I’m wondering
if there is a smaller than 1/32” bit I could use to drill
pilot holes first?? Going to take a lot longer
unfortunately.?
?
Another option
might be to hand drill?
?
?
Carbide bits are pretty cheap (at least resharpened bits are)
and will be much sharper to start and will last much longer.
They also have a larger shank for the drill motor to grip. A
carbide bit will break if the drill motor is not extremely
good; it needs to have very little runout and absolutely no
wobble.
High speed steel will dull very quickly in circuit board
stock, especially in glass-based (like FR4) but phenolic/paper
stock is surprisingly abrasive.
Donald.
--
*Plain Text* email -- it's an accessibility issue
() no proprietary attachments; no html mail
/\
On 25-Sep-2018 00:54, unclefalter via
Groups.Io wrote:
Thanks Rob.?
Yeah, the issue I have is with the holes along the bottom
of those boards for the bus.? Everywhere else has been
mostly fine.? But the bit sort of goes through them, and
then they wrap themselves around the drill bit and pull
off.
?
I’ve got pics
of the board I’ve made and the artwork:
?
The bit I am
using is a Dremel 1/32” (?) bit.. it comes in a pack of 6
of them, it’s the very smallest one.? Seems pretty sharp
to me but maybe not.? I’ve tried different speed settings
with the dremel to see if that helps but so far no dice.
?
That’s cool
re your CP/M system – I just bought a Ferguson Big Board
II that was setup that way also.? Unfortunately the
previous owner decided to toss the case, keyboard and
floppies.? Fortunately they saved the board.
?
Brad
?
?
Found some
pictures of Jon Titus’ Mark-8.
My first computer was a CP/M 8 user system with two 8 inch
floppies.
If you are drilling those really tight IC pads you might
need sharper drill bits.
On 09/25/2018 12:17 AM, Rob via
Groups.Io wrote:
I use a #60 drill bit and have
found that a dull bit makes a mess or breaks.
I like a larger trace and landing size for my home
brewed circuits.
I always make a dough nut or cross shape in the artwork
so the drill bit
will waltz into the PCB without binding too much with
the copper.
?
I often get dozens of PCBs out of one #60? drill bit
before it breaks.
I used to use smaller drill bits ..#70.. but concluded
that the smaller
hole was not worth breaking 2 bits on each PCB.
?
On 09/24/2018 11:34 PM, unclefalter
via Groups.Io wrote:
Hi guys,
?
So I’m working on a replica of Jon
Titus’ Mark-8.? I’ve made a set of boards using his
plans, and also using some 1973 vintage blank PCB stock
to etch them on.? So far so good, but I’m running into a
problem along the bottom of the board – there are a
series of very small holes/pads that have to be drilled
through for the bus.? I’m using a dremel with a 1/32”
bit and I had the foresight to put holes in each of the
pads.? Regardless, the drill is simply wrapping them
around the shaft and pulling them off the board.? Not
sure what I can do here.. any recommendations?? Should I
have done the drilling before I etched?
?
Brad
?
?
?
?
|
This is just an out of the box thought that may or may not work.? But can you put the board on a light table or something similar and mark where to drill on the opposite side of the pads and then drill from that side?? If the board is simultaneously held down tight against a board that might help keeping the pads from being ripped off. Just a thought. Mike K5ESS ?
toggle quoted message
Show quoted text
From: [email protected] [mailto:[email protected]] On Behalf Of unclefalter via Groups.Io
Sent: Wednesday, September 26, 2018 9:04 PM
To: [email protected]
Subject: Re: [homebrewpcbs] Small pads breaking off while drilling Jon Titus' Mark-8.? The bit I’m using is brand new, so I don’t think it’s a sharpness issue.? I had to buy a new one after my old one snapped while doing some other work.? I’m feeling like these pads are just too small in diameter, as mentioned.? I’m wondering if there is a smaller than 1/32” bit I could use to drill pilot holes first?? Going to take a lot longer unfortunately.? ? Another option might be to hand drill? ? ? Carbide bits are pretty cheap (at least resharpened bits are) and will be much sharper to start and will last much longer. They also have a larger shank for the drill motor to grip. A carbide bit will break if the drill motor is not extremely good; it needs to have very little runout and absolutely no wobble. High speed steel will dull very quickly in circuit board stock, especially in glass-based (like FR4) but phenolic/paper stock is surprisingly abrasive. Donald.
-- *Plain Text* email -- it's an accessibility issue () no proprietary attachments; no html mail /\ On 25-Sep-2018 00:54, unclefalter via Groups.Io wrote: Thanks Rob.? Yeah, the issue I have is with the holes along the bottom of those boards for the bus.? Everywhere else has been mostly fine.? But the bit sort of goes through them, and then they wrap themselves around the drill bit and pull off. ? I’ve got pics of the board I’ve made and the artwork: ? The bit I am using is a Dremel 1/32” (?) bit.. it comes in a pack of 6 of them, it’s the very smallest one.? Seems pretty sharp to me but maybe not.? I’ve tried different speed settings with the dremel to see if that helps but so far no dice. ? That’s cool re your CP/M system – I just bought a Ferguson Big Board II that was setup that way also.? Unfortunately the previous owner decided to toss the case, keyboard and floppies.? Fortunately they saved the board. ? Brad ? ? Found some pictures of Jon Titus’ Mark-8.
My first computer was a CP/M 8 user system with two 8 inch floppies.
If you are drilling those really tight IC pads you might need sharper drill bits. On 09/25/2018 12:17 AM, Rob via Groups.Io wrote: I use a #60 drill bit and have found that a dull bit makes a mess or breaks.
I like a larger trace and landing size for my home brewed circuits.
I always make a dough nut or cross shape in the artwork so the drill bit
will waltz into the PCB without binding too much with the copper.
?
I often get dozens of PCBs out of one #60? drill bit before it breaks.
I used to use smaller drill bits ..#70.. but concluded that the smaller
hole was not worth breaking 2 bits on each PCB.
?
On 09/24/2018 11:34 PM, unclefalter via Groups.Io wrote: Hi guys, ? So I’m working on a replica of Jon Titus’ Mark-8.? I’ve made a set of boards using his plans, and also using some 1973 vintage blank PCB stock to etch them on.? So far so good, but I’m running into a problem along the bottom of the board – there are a series of very small holes/pads that have to be drilled through for the bus.? I’m using a dremel with a 1/32” bit and I had the foresight to put holes in each of the pads.? Regardless, the drill is simply wrapping them around the shaft and pulling them off the board.? Not sure what I can do here.. any recommendations?? Should I have done the drilling before I etched? ? Brad ?
?
?
?
|
How about drilling all the holes (or the ones in question) first then etching the PCB.
By doing it this way the problem will just go away.?
|
Hello Homebrewpcbs,
Thursday, September 27, 2018
The elegant simplicity of that approach is wonderful, but my only
concern is whether the etchant might leech under the copper around
the newly drilled holes. As it does not at the edges of a board this
may well be a somewhat pessimistic thought :)
Best regards,
Chris mailto:chris@...
bue> How about drilling all the holes (or the ones in question) first then etching the PCB.
bue> By doing it this way the problem will just go away.
|
Do not create new problems by using strange processes.
Zillions of small PCB holes are being drilled commercially and by hobbyists
without a problem.
Use sharp bits
A rigid setup that will accurately move the bit up and down without wobble
or play.
A backing plate
HIGH rpm
It should work just fine.
Bertho
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if you use toner transfer or pre sensitized ones for uv exposure,? pre drilling might disturb the coating due to vibration.
Those who use screen print and cnc drilling? would prefer pre-drilling thro hole deposition etc. ?regards sarma vu3zmv
?
On Thu, Sep 27, 2018 at 5:42 PM < bnf@...> wrote: How about drilling all the holes (or the ones in question) first then etching the PCB.
By doing it this way the problem will just go away.?
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On Thu, 27 Sep 2018 18:46:18 +0530, you wrote: if you use toner transfer or pre sensitized ones for uv exposure, pre
drilling might disturb the coating due to vibration.
Those who use screen print and cnc drilling would prefer pre-drilling thro
hole deposition etc. If the drilling leaves a small ridge around the hole, then toner transfer may not get to all the board around the hole. I can also see the drilling cracking and flaking the photoresist. For CNC etching or screen printing, this does not make as much a difference. For plated through holes, predrilling is required. Use a drill press with carbide drills, and the highest speed possible. Do not attempt to drill by hand. While a dremel tool in a stand will work, the runout (drill bit wobble) is horrible. You'd do better with a proxxon, the 12 volt model works just fine. Again, a stand is required to avoid bit breaking. However, it also seems as if your lands are simply to small in comparison to the hole, and it would be well if you could increase the size of the pad or decrease the size of the hole. Likely these were originally done commercially, which does not have the problems. I checked an old design, and I have a 0.023 drill with a 0.039 pad for a wired via. I have had no problems drilling these, but you must center the pad. I used toner transfer. Harvey regards
sarma vu3zmv
On Thu, Sep 27, 2018 at 5:42 PM <bnf@...> wrote:
How about drilling all the holes (or the ones in question) first then
etching the PCB.
By doing it this way the problem will just go away.
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Bertho