|
I had to make a new worm gear for an N gauge loco, 5mm dia 1mm pitch in brass, the only issue was it needed a 0.8mm (32 thou) hole for the motor shaft. the first one i made I threaded the outside of some 5mm brass rod, then tried to drill using a standard 0.8mm drill bit. now centering the drill is the main issue, and though it looked good, when mounted on the motor shaft and taken to full speed, there was vibration. so i had another go today, this time using a 0.8mm carbide PCB drill, these have a 3mm shank and a drill section about 1/2" long, being very careful when starting the drill, barely touching and just very gently started the drill- now these drills will break if you breath on them wrong, but i managed to get the drill centred with no apparent wobble, then pushing my luck I drilled to a depth of about 10mm (3/8") this went on the motor nicely, but was a little loose, so I tried again with a 0.7mm PCB drill and that one was too tight (maybe a press fit, i am not sure. needless to say, the n gauge loco is now running smoothly. I do love the precision i can get from my unimat 3. does anyone else have any techniques for drilling similar small bore centre holes? Peter
|
I start with a centre drill, the smallest that I can find. You only really need a dimple, just enough so that the drill won't wobble as it starts. Rather than drill to the finished size I use a smaller drill followed by a chucking reamer, these are straight rather than tapered. Or if you don't have one or don't want to buy one for a one-off job drill undersize and finish with a tapered broach, I've done that when opening out worms. Go steady and keep checking the fit. I also use a collet chuck in the tailstock. I used to use an ER16 one before I found an ER11 replacement ram. Well worth the expense if, like me, you're making small parts for model locos.
Small centre drill:?
Some waffle about tailstock rams:?
Paul B.
On Monday 3 February 2025 at 19:45:45 GMT, Peter ashby via groups.io <aescinga.pgen@...> wrote:
I had to make a new worm gear for an N gauge loco, 5mm dia 1mm pitch in brass, the only issue was it needed a 0.8mm (32 thou) hole for the motor shaft. the first one i made I threaded the outside of some 5mm brass rod, then tried to drill using a standard 0.8mm drill bit. now centering the drill is the main issue, and though it looked good, when mounted on the motor shaft and taken to full speed, there was vibration. so i had another go today, this time using a 0.8mm carbide PCB drill, these have a 3mm shank and a drill section about 1/2" long, being very careful when starting the drill, barely touching and just very gently started the drill- now these drills will break if you breath on them wrong, but i managed to get the drill centred with no apparent wobble, then pushing my luck I drilled to a depth of about 10mm (3/8") this went on the motor nicely, but was a little loose, so I tried again with a 0.7mm PCB drill and that one was too tight (maybe a press fit, i am not sure. needless to say, the n gauge loco is now running smoothly. I do love the precision i can get from my unimat 3. does anyone else have any techniques for drilling similar small bore centre holes? Peter
|
Hi Peter:
Any center
drill will help you start straighter than just the drill. I
might suggest drill the hole first, mount the blank on a
mandrill and then cut the teeth. That way if you bust the drill
in the blank, you don't loose all the gear cutting time.
This is one
way to improve hole accuracy: drill the hole and then grind the
sides to size. I did a punch this way, two 1mm die holes in a
2.5x10mm punch (it made a part like a chain link for a watch
crystal base). It made nice parts, but in the end the whole
project was scraped.
Carl.
On 2/3/2025 2:45 PM, Peter ashby via
groups.io wrote:
toggle quoted message
Show quoted text
I had to make a new worm gear for an N gauge loco, 5mm dia 1mm
pitch in brass, the only issue was it needed a 0.8mm (32 thou)
hole for the motor shaft.
the first one i made I threaded the outside of some 5mm brass
rod, then tried to drill using a standard 0.8mm drill bit. now
centering the drill is the main issue, and though it looked
good, when mounted on the motor shaft and taken to full speed,
there was vibration.
so i had another go today, this time using a 0.8mm carbide
PCB drill, these have a 3mm shank and a drill section about 1/2"
long, being very careful when starting the drill, barely
touching and just very gently started the drill- now these
drills will break if you breath on them wrong, but i managed to
get the drill centred with no apparent wobble, then pushing my
luck I drilled to a depth of about 10mm (3/8") this went on the
motor nicely, but was a little loose, so I tried again with a
0.7mm PCB drill and that one was too tight (maybe a press fit, i
am not sure.
needless to say, the n gauge loco is now running smoothly.
I do love the precision i can get from my unimat 3.
does anyone else have any techniques for drilling similar
small bore centre holes?
Peter
|
I am in the US.? A center drill for this application is a size 00, which is .025" tip diameter.? Here on Ebay is one that is still made in the US, not China.
132219336138
|
yes a mandrel just isnt going to be strong wnough, as it would have to pass through the 0.8mm (32 thousandths) hole even if you have faced off perfectly, any tiny nub on the part will deflect the drill bit, even the bottom of a centre hole can deflect the bit as it wanders round the inside of the centre hole. the smallest uk centre bit i can find (30.100) has a 1mm point which limits the error, I see the USA has 2 small 0 and 00 sizes that might suit,, but drilling these tiny holes is a trial of patience i think. On Mon, 3 Feb 2025 17:24:43 -0500 "Carl via groups.io" <carl.blum@...> wrote: Hi Peter:
Any center drill will help you start straighter than just the drill. I
might suggest drill the hole first, mount the blank on a mandrill and
then cut the teeth. That way if you bust the drill in the blank, you
don't loose all the gear cutting time.
This is one way to improve hole accuracy: drill the hole and then grind
the sides to size. I did a punch this way, two 1mm die holes in a
2.5x10mm punch (it made a part like a chain link for a watch crystal
base). It made nice parts, but in the end the whole project was scraped.
Carl.
On 2/3/2025 2:45 PM, Peter ashby via groups.io wrote:
I had to make a new worm gear for an N gauge loco, 5mm dia 1mm pitch
in brass, the only issue was it needed a 0.8mm (32 thou) hole for the
motor shaft.
the first one i made I threaded the outside of some 5mm brass rod,
then tried to drill using a standard 0.8mm drill bit. now centering
the drill is the main issue, and though it looked good, when mounted
on the motor shaft and taken to full speed, there was vibration.
so i had another go today, this time using a 0.8mm carbide PCB drill,
these have a 3mm shank and a drill section about 1/2" long, being very
careful when starting the drill, barely touching and just very gently
started the drill- now these drills will break if you breath on them
wrong, but i managed to get the drill centred with no apparent wobble,
then pushing my luck I drilled to a depth of about 10mm (3/8") this
went on the motor nicely, but was a little loose, so I tried again
with a 0.7mm PCB drill and that one was too tight (maybe a press fit,
i am not sure.
needless to say, the n gauge loco is now running smoothly.
I do love the precision i can get from my unimat 3.
does anyone else have any techniques for drilling similar small bore
centre holes?
Peter
-- Peter Ashby <aescinga.pgen@...>
|
The first problem I had just chucking the tiny drill bit .
So look found a junk check it did hold drill bit well.?
?
So look at Jacob and purchased 0 size 0 to 5/32" . It great and was straight.?
Purchased back 1970’s and still tool box just for tiny drill bits only.?
?
I would only by Jacob's?
It not because the could better I just do not know and this a one time purchase and will last a life time.
?
Dave?
?
|
Dave, what is a ‘Junk Check’?
I have never heard of that for drilling.
--
http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
?MINI-LATHE CARRIAGE LOCK PLANS
?SMALL QC TOOL POST PLANS?
?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT MODIFICATION
|
He meant "chuck", but his autocorrect is probably on.
toggle quoted message
Show quoted text
Dave, what is a ‘Junk Check’?
I have never heard of that for drilling.
--
http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL
TURRET TOOL POST PLANS?
?LARGE
TURRET TOOL POST PLANS
?MINI-LATHE
CARRIAGE LOCK PLANS
?SMALL
QC TOOL POST PLANS?
?QUICK
CHANGE LATHE TURRET
?MINI
LATHE COMPOUND PIVOT MODIFICATION
|
Hi Dave:
The chuck for
small drills is an Albrecht:
C15 and C30
are for 1.5 and 3mm drills max.
They also
make a shank with a finger feed ring.
Carl.
On 2/4/2025 4:39 AM, davesmith1800
wrote:
toggle quoted message
Show quoted text
The first problem I had just chucking the tiny drill bit .
So look found a junk check it did hold drill bit well.?
?
So look at Jacob and purchased 0 size 0 to 5/32" . It great
and was straight.?
Purchased back 1970’s and still tool box just for tiny drill
bits only.?
?
I would only by Jacob's?
It not because the could better I just do not know and this a
one time purchase and will last a life time.
?
Dave?
?
|
I would not use an Albrecht chuck on a Unimat.?
First, it costs more than the lathe and second, it is physically too big and will eat up some of the work envelope of the lathe.?
There are plenty of good Jacob's or Rohm standard chucks that can accommodate any size drill that is suitable for a Unimat.
toggle quoted message
Show quoted text
Hi Dave:
The chuck for small drills is an Albrecht:
C15 and C30 are for 1.5 and 3mm drills max.
They also make a shank with a finger feed ring.
Carl.
On 2/4/2025 4:39 AM, davesmith1800 wrote:
The first problem I had just chucking the tiny drill bit .
So look found a junk check it did hold drill bit well.?
?
So look at Jacob and purchased 0 size 0 to 5/32" . It great and was straight.?
Purchased back 1970’s and still tool box just for tiny drill bits only.?
?
I would only by Jacob's?
It not because the could better I just do not know and this a one time purchase and will last a life time.
?
Dave?
?
|
Paul,
Can I ask if you are in the UK did you have any problems importing the ER11 tailstock shaft and collets from Germany?
?
Phill?
?
|
I did a lot of small hole drilling on my SL, and then on the U3, including small flywheels for model railway use. First I used collets both on the spindle and in the tailstock. Concentricity was good and I started with good quality brass bar, which is round and accurate to better than 0.02 mm.. I had to drill it 1.0 mm, to be a good fit on a 0.995 mm shaft. I found drilling to the "correct" size never worked - drills usually cut oversize in metal. I tried slightly smaller drills - 0.97 & 0.98 mm - but the size hole it made depended on the bit of bar I was cutting. The bars were all hard drawn but it was noticeable that the centre of a 10 mm bar was a lot softer then 7 mm, so in 10 mm the holes were bigger.
?
What worked was to drill 0.9 mm, then with 1.0 mm. When a drill opens up an existing hole it cuts undersize. this gave me a hole about 0.99 mm diameter. When checked with a bit of shafting the test shaft was a bit tight in the hole, fitting but squeaking. A final cut with a 1 mm reamer gave a good fit on the shaft. With the collet and the good quality bar they flywheels ran true and balanced without turning the outside diameter - I just gave that a quick spin with very fine wet & dry, and a bit of a polish.
?
If you check the actual diameter of a 1.0 mm drill is a bit less to compensate for the tip wandering. Better quality drills are nearer to the correct size as they wander less. The one I was using was 0.99 mm according to the micrometer. Small hole drilling can be tricky.
?
It is unlikely that the worm pitch is 1.0 mm. It is probably 0.3 Mod, which is 0.3 × π, IE 0.942 mm, but the helix angle will increase the linear pitch to about 0.95 mm. You might well get away with it. Make sure that all the machining is done in one setup to make sure everything is concentric.
|
Hi,
I use a pin vice in a chuck or a collet, depending on what accuracy I? need, to hold the drill.
Before the drill bit I will use a centre drill.
It works for me.
I have used the "drill 0.95m and then 1.00mm" technique and it worked for 8.00mm brass flywheels.
Cheers,
James
On Tue, 4 Feb 2025, 14:39 Keith S. Angus via , <keithsangus= [email protected]> wrote: I did a lot of small hole drilling on my SL, and then on the U3, including small flywheels for model railway use. First I used collets both on the spindle and in the tailstock. Concentricity was good and I started with good quality brass bar, which is round and accurate to better than 0.02 mm.. I had to drill it 1.0 mm, to be a good fit on a 0.995 mm shaft. I found drilling to the "correct" size never worked - drills usually cut oversize in metal. I tried slightly smaller drills - 0.97 & 0.98 mm - but the size hole it made depended on the bit of bar I was cutting. The bars were all hard drawn but it was noticeable that the centre of a 10 mm bar was a lot softer then 7 mm, so in 10 mm the holes were bigger.
?
What worked was to drill 0.9 mm, then with 1.0 mm. When a drill opens up an existing hole it cuts undersize. this gave me a hole about 0.99 mm diameter. When checked with a bit of shafting the test shaft was a bit tight in the hole, fitting but squeaking. A final cut with a 1 mm reamer gave a good fit on the shaft. With the collet and the good quality bar they flywheels ran true and balanced without turning the outside diameter - I just gave that a quick spin with very fine wet & dry, and a bit of a polish.
?
If you check the actual diameter of a 1.0 mm drill is a bit less to compensate for the tip wandering. Better quality drills are nearer to the correct size as they wander less. The one I was using was 0.99 mm according to the micrometer. Small hole drilling can be tricky.
?
It is unlikely that the worm pitch is 1.0 mm. It is probably 0.3 Mod, which is 0.3 × π, IE 0.942 mm, but the helix angle will increase the linear pitch to about 0.95 mm. You might well get away with it. Make sure that all the machining is done in one setup to make sure everything is concentric.
--
James Batchelor?
Dunfermline, Fife, UK.?
07805 207238
|
No problems Phil, I bought mine through ebay;?
I didn't even get the dreaded extra charges when it arrived, but that will be down to luck.
Paul B. In the UK.
On Tuesday 4 February 2025 at 14:23:06 GMT, phill005 via groups.io <phill05@...> wrote:
Paul,
Can I ask if you are in the UK did you have any problems importing the ER11 tailstock shaft and collets from Germany?
?
Phill?
?
|
Many thanks for that Paul, I will give it a try.
?
I did contact two companies in the EU and they did not want to bother with all the paperwork.
?
Thanks Phill
|
Ebay or aliexpress is your friend here. Can't beat 30 bucks for a set of collets. If you find one that is bad, buy a replacement online. Even amazon sells them.
toggle quoted message
Show quoted text
Many thanks for that Paul, I will give it a try.
?
I did contact two companies in the EU and they did not want to bother with all the paperwork.
?
Thanks Phill
|
Beware you might get a picture of what you ordered. That's been in the news for aliexpress recently.
William R. Meyers, MSgt, USAF(Ret.)
Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY!
Expect in one hand, expectorate in the other. See which one gets full first.
On Tuesday, February 4, 2025 at 12:12:13 PM CST, Andrei via groups.io <calciu1@...> wrote:
Ebay or aliexpress is your friend here. Can't beat 30 bucks for a set of collets. If you find one that is bad, buy a replacement online. Even amazon sells them.
Many thanks for that Paul, I will give it a try.
?
I did contact two companies in the EU and they did not want to bother with all the paperwork.
?
Thanks Phill
|
Oh, might also try Amazon.com or the various national versions. I've bought a few things from amazon.co.uk, for example. Also, Arc EuroTrade in Europe, and littlemachineshop.com in the US sell some stuff that will fit Unimats, and several sizes of collets.?
William R. Meyers, MSgt, USAF(Ret.)
Aphorisms to live by: Good judgement comes from experience. Experience comes from bad judgement.? SEMPER GUMBY!
Expect in one hand, expectorate in the other. See which one gets full first.
On Tuesday, February 4, 2025 at 12:12:13 PM CST, Andrei via groups.io <calciu1@...> wrote:
Ebay or aliexpress is your friend here. Can't beat 30 bucks for a set of collets. If you find one that is bad, buy a replacement online. Even amazon sells them.
Many thanks for that Paul, I will give it a try.
?
I did contact two companies in the EU and they did not want to bother with all the paperwork.
?
Thanks Phill
|
Hi Gang:
I've ordered
from ArcEuroTrade several times and they have always delivered
good products. Fair price and shipping too.
Carl.
On 2/4/2025 1:36 PM, Bill in OKC too
via groups.io wrote:
toggle quoted message
Show quoted text
Oh, might also try Amazon.com or the various national
versions. I've bought a few things from amazon.co.uk, for
example. Also, Arc EuroTrade in Europe, and
littlemachineshop.com in the US sell some stuff that will
fit Unimats, and several sizes of collets.?
William R.
Meyers, MSgt, USAF(Ret.)
|
Andre, What size collets are you talking about?
--
http://www.homemadetools.net/forum/?OFF-SET-tailstock-center-65965#post105972
?SMALL TURRET TOOL POST PLANS?
?LARGE TURRET TOOL POST PLANS
?MINI-LATHE CARRIAGE LOCK PLANS
?SMALL QC TOOL POST PLANS?
?QUICK CHANGE LATHE TURRET
?MINI LATHE COMPOUND PIVOT MODIFICATION
|
Carl
davesmith1800
OldToolmaker
James Batchelor
Bill in OKC too