I got a rototiller at the dump. The motor is fine, but it wouldn't
shift gears. The "transmission" was a bitch to get apart, but I did it
and found rust, as I expected. I'm undecided between pitching it and
rehabbing it.

Even with the rust removed, the gears will be very rough and wear
quickly, but:
- it would get very little use (maybe an hour or two per year)
- the transmission runs at fairly low speed (900 rpm max input, down to
maybe 50 rpm on the wheels)
- it only handles 5 hp

My feeling is that under these conditions the transmission would last a
long time and perform normally, if noisily.

Finally, I like to rehab machines, but I don't like to waste my time.

A pic of one of the gears after HCl de-rusting and bead blasting (the
teeth are about 1/4" wide):
http://home.comcast.net/~bobengelhardt/RustedGear.jpg

Waddaya think?

Bob

On Sun, 13 Jan 2008 19:57:28 -0500, Bob Engelhardt wrote:

Even with the rust removed, the gears will be very rough and wear
quickly, but:
- it would get very little use (maybe an hour or two per year)
- the transmission runs at fairly low speed (900 rpm max input, down to
maybe 50 rpm on the wheels)
- it only handles 5 hp
http://home.comcast.net/~bobengelhardt/RustedGear.jpg
Waddaya think?

I'd run it as is. Worst case you're without a machine if it breaks. If
you toss it now, you're out a machine regardless. All you're out is
reassembly time and a few bucks worth of gear lube. The pitting is
pretty fugly but, the high spots will wear off down to the point where
there's enough contact to handle the load. You'll have a bit more lash
in the geartrain than spec but, like you say, low duty cycle, low load.
And it's low risk, it's not like you're fixing an airplane or
something... When it blows, I don't think it'll be from pits on the
gears.

On 14 Jan 2008 01:11:06 GMT, Dave Hinz wrote:

On Sun, 13 Jan 2008 19:57:28 -0500, Bob Engelhardt wrote:

Even with the rust removed, the gears will be very rough and wear
quickly, but:
- it would get very little use (maybe an hour or two per year)
- the transmission runs at fairly low speed (900 rpm max input, down to
maybe 50 rpm on the wheels)
- it only handles 5 hp
http://home.comcast.net/~bobengelhardt/RustedGear.jpg
Waddaya think?

I'd run it as is. Worst case you're without a machine if it breaks. If
you toss it now, you're out a machine regardless. All you're out is
reassembly time and a few bucks worth of gear lube. The pitting is
pretty fugly but, the high spots will wear off down to the point where
there's enough contact to handle the load. You'll have a bit more lash
in the geartrain than spec but, like you say, low duty cycle, low load.
And it's low risk, it's not like you're fixing an airplane or
something... When it blows, I don't think it'll be from pits on the
gears.
Give it some heavy lube and it will outlast you.
Gerry :-)}
London, Canada

I'm with Dave, an hour a year will not give you any problems. I WILL
have excessive backlash but that is not an issue on a tiller.

Dave Hinz wrote:
On Sun, 13 Jan 2008 19:57:28 -0500, Bob Engelhardt wrote:
Even with the rust removed, the gears will be very rough and wear
quickly, but:
- it would get very little use (maybe an hour or two per year)
- the transmission runs at fairly low speed (900 rpm max input, down to
maybe 50 rpm on the wheels)
- it only handles 5 hp
http://home.comcast.net/~bobengelhardt/RustedGear.jpg
Waddaya think?

I'd run it as is. Worst case you're without a machine if it breaks. If
you toss it now, you're out a machine regardless. All you're out is
reassembly time and a few bucks worth of gear lube. The pitting is
pretty fugly but, the high spots will wear off down to the point where
there's enough contact to handle the load. You'll have a bit more lash
in the geartrain than spec but, like you say, low duty cycle, low load.
And it's low risk, it's not like you're fixing an airplane or
something... When it blows, I don't think it'll be from pits on the
gears.

"Bob Engelhardt" wrote in message
. ..
I got a rototiller at the dump. The motor is fine, but it wouldn't shift
gears. The "transmission" was a bitch to get apart, but I did it and found
rust, as I expected. I'm undecided between pitching it and rehabbing it.

Even with the rust removed, the gears will be very rough and wear quickly,
but:
- it would get very little use (maybe an hour or two per year)
- the transmission runs at fairly low speed (900 rpm max input, down to
maybe 50 rpm on the wheels)
- it only handles 5 hp

My feeling is that under these conditions the transmission would last a
long time and perform normally, if noisily.

Finally, I like to rehab machines, but I don't like to waste my time.

A pic of one of the gears after HCl de-rusting and bead blasting (the
teeth are about 1/4" wide):
http://home.comcast.net/~bobengelhardt/RustedGear.jpg

Waddaya think?

Bob



Have you tried the Electrolytic method of de-rusting?

http://woodmangler.com/Derusting/ele...derusting.html

http://www.stovebolt.com/techtips/ru..._derusting.htm

http://www.hobartwelders.com/weldtal...?t=1737&page=1

Works great. Cheap and no acid involved.

mark

On Jan 13, 7:57*pm, Bob Engelhardt wrote:
I got a rototiller at the dump. *The motor is fine, but it wouldn't
shift gears. *The "transmission" was a bitch to get apart, but I did it
and found rust, as I expected. *I'm undecided between pitching it and
rehabbing it.

Even with the rust removed, the gears will be very rough and wear
quickly, but:
- it would get very little use (maybe an hour or two per year)
- the transmission runs at fairly low speed (900 rpm max input, down to
maybe 50 rpm on the wheels)
- it only handles 5 hp

My feeling is that under these conditions the transmission would last a
long time and perform normally, if noisily.

Finally, I like to rehab machines, but I don't like to waste my time.

A pic of one of the gears after HCl de-rusting and bead blasting (the
teeth are about 1/4" wide):http://home.comcast.net/~bobengelhardt/RustedGear.jpg

Waddaya think?

Bob

I've got an old Gravely tractor and several gearboxes for the rotary
plow and rototiller attachments. The gearbox has a ring and pinion
gear setup very like that in an auto rear end. About the same size as
auto ring & pinion gears. Pinion runs at PTO speed which, as I
recall, is at least 1,200 RPM.

The pinion gears are machined steel, but the ring cears are cast iron
- with no machining of the gear teeth. As long as they are kept
lubricated, they work fine. Horsepower is in the 5 - 7.6 range, but
they can handle more.

If those cast iron gears hold up, I'm guessing yours will as well. If
not, well, it's a rototiller. It's not likely to leave you stranded
in downtown Birmingham.

John Martin

RoyJ wrote:

I WILL have excessive backlash...


Can't your doctor do anything? ;-)


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

On 2008-01-14, Dave Hinz wrote:
I'd run it as is. Worst case you're without a machine if it breaks. If
you toss it now, you're out a machine regardless. All you're out is
reassembly time and a few bucks worth of gear lube. The pitting is
pretty fugly but, the high spots will wear off down to the point where
there's enough contact to handle the load. You'll have a bit more lash
in the geartrain than spec but, like you say, low duty cycle, low load.
And it's low risk, it's not like you're fixing an airplane or
something... When it blows, I don't think it'll be from pits on the
gears.


I think that something else will break before the gears. I agree with
Dave.

i

Gotta start proofreading these. Blush.

Michael A. Terrell wrote:
RoyJ wrote:
I WILL have excessive backlash...


Can't your doctor do anything? ;-)

I think the pitting will significantly increase gear noise but won't
significantly change anything else. I might try some hi-tech moly grease
since it's in a gear case.

Grant

Bob Engelhardt wrote:

I got a rototiller at the dump. The motor is fine, but it wouldn't
shift gears. The "transmission" was a bitch to get apart, but I did it
and found rust, as I expected. I'm undecided between pitching it and
rehabbing it.

Even with the rust removed, the gears will be very rough and wear
quickly, but:
- it would get very little use (maybe an hour or two per year)
- the transmission runs at fairly low speed (900 rpm max input, down to
maybe 50 rpm on the wheels)
- it only handles 5 hp

My feeling is that under these conditions the transmission would last a
long time and perform normally, if noisily.

Finally, I like to rehab machines, but I don't like to waste my time.

A pic of one of the gears after HCl de-rusting and bead blasting (the
teeth are about 1/4" wide):
http://home.comcast.net/~bobengelhardt/RustedGear.jpg

Waddaya think?

Bob



--
Posted via a free Usenet account from http://www.teranews.com

RoyJ wrote:

Gotta start proofreading these. Blush.

Michael A. Terrell wrote:
RoyJ wrote:
I WILL have excessive backlash...


Can't your doctor do anything? ;-)




Sometime I just can't pass up a funny typo.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

On 14 Jan 2008 01:11:06 GMT, Dave Hinz wrote:

On Sun, 13 Jan 2008 19:57:28 -0500, Bob Engelhardt wrote:

Even with the rust removed, the gears will be very rough and wear
quickly, but:
- it would get very little use (maybe an hour or two per year)
- the transmission runs at fairly low speed (900 rpm max input, down to
maybe 50 rpm on the wheels)
- it only handles 5 hp
http://home.comcast.net/~bobengelhardt/RustedGear.jpg
Waddaya think?

I'd run it as is. Worst case you're without a machine if it breaks. If
you toss it now, you're out a machine regardless. All you're out is
reassembly time and a few bucks worth of gear lube. The pitting is
pretty fugly but, the high spots will wear off down to the point where
there's enough contact to handle the load. You'll have a bit more lash
in the geartrain than spec but, like you say, low duty cycle, low load.
And it's low risk, it's not like you're fixing an airplane or
something... When it blows, I don't think it'll be from pits on the
gears.


I just "fixed" an elderly Milwaukee right angle Hole Hawg. Thing had
the power cord amputated at the handle, the trigger switch was cracked
into 2 pieces (JB Weld) and the reduction gears and bearings were
rusted into an amorphous mass. Found head down in a 5 gallon
bucket...under an eve.

I left it soaking head down..in a bucket of diesel for a couple weeks,
then hammered the gear cover off and the gears apart. All them needle
bearings...mass of rust. Wire wheeled the gears until I could see the
teeth again, soaked the head in PBlaster for another week, then
reassembled it. Sounds like a coffee can filled with #3 granite..but
since its only going to drill a few holes a year...I can live with it.
I shudder to think of what Milwaulkee will want for a complete bearing
package..and the armature needs a turning... so when it goes..it goes
into the circular file. But I figure the tired old bitch will smooth
out a little bit and then run for a few more years.

Gunner

Gunner wrote:

I just "fixed" an elderly Milwaukee right angle Hole Hawg. Thing had
the power cord amputated at the handle, the trigger switch was cracked
into 2 pieces (JB Weld) and the reduction gears and bearings were
rusted into an amorphous mass. Found head down in a 5 gallon
bucket...under an eve.

I left it soaking head down..in a bucket of diesel for a couple weeks,
then hammered the gear cover off and the gears apart. All them needle
bearings...mass of rust. Wire wheeled the gears until I could see the
teeth again, soaked the head in PBlaster for another week, then
reassembled it. Sounds like a coffee can filled with #3 granite..but
since its only going to drill a few holes a year...I can live with it.
I shudder to think of what Milwaulkee will want for a complete bearing
package..and the armature needs a turning... so when it goes..it goes
into the circular file. But I figure the tired old bitch will smooth
out a little bit and then run for a few more years.

Gunner


Gunner, have you ever used a variable DC power supply and an ink
eraser to polish a worn commutator? I've done it to hundreds of vacuum
cleaner motors, as well as power tools. I connect the motor to the
power supply, then bring the voltage up slowly till the motor is
turning, slowly. Then I use the ink eraser to polish the copper
segments.




--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

On Mon, 14 Jan 2008 02:40:36 -0500, "Michael A. Terrell"
wrote:

Gunner wrote:

I just "fixed" an elderly Milwaukee right angle Hole Hawg. Thing had
the power cord amputated at the handle, the trigger switch was cracked
into 2 pieces (JB Weld) and the reduction gears and bearings were
rusted into an amorphous mass. Found head down in a 5 gallon
bucket...under an eve.

I left it soaking head down..in a bucket of diesel for a couple weeks,
then hammered the gear cover off and the gears apart. All them needle
bearings...mass of rust. Wire wheeled the gears until I could see the
teeth again, soaked the head in PBlaster for another week, then
reassembled it. Sounds like a coffee can filled with #3 granite..but
since its only going to drill a few holes a year...I can live with it.
I shudder to think of what Milwaulkee will want for a complete bearing
package..and the armature needs a turning... so when it goes..it goes
into the circular file. But I figure the tired old bitch will smooth
out a little bit and then run for a few more years.

Gunner


Gunner, have you ever used a variable DC power supply and an ink
eraser to polish a worn commutator? I've done it to hundreds of vacuum
cleaner motors, as well as power tools. I connect the motor to the
power supply, then bring the voltage up slowly till the motor is
turning, slowly. Then I use the ink eraser to polish the copper
segments.

No, Ive not. Works well I take it?

Gunner

On Mon, 14 Jan 2008 01:00:49 -0800, with neither quill nor qualm,
Gunner quickly quoth:

On Mon, 14 Jan 2008 02:40:36 -0500, "Michael A. Terrell"
wrote:
Gunner, have you ever used a variable DC power supply and an ink
eraser to polish a worn commutator? I've done it to hundreds of vacuum
cleaner motors, as well as power tools. I connect the motor to the
power supply, then bring the voltage up slowly till the motor is
turning, slowly. Then I use the ink eraser to polish the copper
segments.

No, Ive not. Works well I take it?

If you don't have a power eraser handy, don't worry. The back end of
any #2 pencil will polish that commutator just as well and nearly as
quickly. Sand smooth with crocus or fine sandpaper, clean between the
segments with an ice pick, then polish with the eraser. Works like a
charm.

That old Wilton 4x6 bandsaw locked up on me the last time I tried to
use it. I guess I'll have to find a gearset for it after all. sigh

---
Chaos, panic, and disorder--my work here is done.

On Jan 13, 4:57 pm, Bob Engelhardt wrote:
I got a rototiller at the dump. The motor is fine, but it wouldn't
shift gears. The "transmission" was a bitch to get apart, but I did it
and found rust, as I expected. I'm undecided between pitching it and
rehabbing it.

Even with the rust removed, the gears will be very rough and wear
quickly, but:
- it would get very little use (maybe an hour or two per year)
- the transmission runs at fairly low speed (900 rpm max input, down to
maybe 50 rpm on the wheels)
- it only handles 5 hp

My feeling is that under these conditions the transmission would last a
long time and perform normally, if noisily.

Finally, I like to rehab machines, but I don't like to waste my time.

A pic of one of the gears after HCl de-rusting and bead blasting (the
teeth are about 1/4" wide):http://home.comcast.net/~bobengelhardt/RustedGear.jpg

Waddaya think?

Bob

By the picture, there appears to be pitting only on the non-pressure
side of the gears. The tiller only works in one direction, so the pit-
to-pit side of the teeth will probably never actually get together.
The old cast gears were never made to mesh like machine cut gears. I
would reassemble it, fill with heavy gear lube and be sure there is a
vent on top so the hot oil vapors can escape. Go for it!

Paul

"Ignoramus24964" wrote in message
...
On 2008-01-14, Dave Hinz wrote:
I'd run it as is. Worst case you're without a machine if it breaks. If
you toss it now, you're out a machine regardless. All you're out is
reassembly time and a few bucks worth of gear lube. The pitting is
pretty fugly but, the high spots will wear off down to the point where
there's enough contact to handle the load. You'll have a bit more lash
in the geartrain than spec but, like you say, low duty cycle, low load.
And it's low risk, it's not like you're fixing an airplane or
something... When it blows, I don't think it'll be from pits on the
gears.


I think that something else will break before the gears. I agree with
Dave.

i

Not if the gears are heat treated. THe HCl treatment would have introduced
hydrogen to the gears, making them subject to breakage (hydrogen
embrittlement). They should receive a roast for a couple hours @ 375
degrees F to eliminate the hydrogen.

Harold

Dave Hinz wrote:
I'd run it as is. ...

Can't do that - it's bound up with rust. Minimum of breaking it down,
cleaning off REALLY heavy grease, removing rust, & reassembly. That's
the time I didn't want to waste if it was a lost cause.

When it blows, I don't think it'll be from pits on the gears.

That seems to be the consensus, so I'm gonna do it.

Thanks,
Bob

Harold and Susan Vordos wrote:
Not if the gears are heat treated. THe HCl treatment would have introduced
hydrogen to the gears, making them subject to breakage (hydrogen
embrittlement). They should receive a roast for a couple hours @ 375
degrees F to eliminate the hydrogen.

Good to know! So far I've only derusted the one in the picture. I'll
check them and use another process if they're heat treated. I assume
that hardness is the indicator of heat treating.

Thanks,
Bob

Gunner wrote:
I just "fixed" an elderly Milwaukee right angle Hole Hawg. ...
the reduction gears and bearings were rusted into an amorphous mass. ...
All them needle bearings...mass of rust. ...

Wow - you didn't rehab that drill, you resurrected it! It was dead and
rotting and now it lives! And who would re-use rusted needle bearings?
You're an inspiration, Gunner. I have a rusted needle bearing in this
rototiller - I guess I'll re-use it. Well, maybe not.

Bob

Mark Dunning wrote:
Have you tried the Electrolytic method of de-rusting?
....

Yes, I have. I prefer acid: it's much faster; electrolytic leaves a
really awful gunky residue; the length of the current path affects the
derusting.

Bob

John Martin wrote:
I've got an old Gravely tractor and several gearboxes for the rotary
plow and rototiller attachments. ...

Hey, me too. A couple of years ago I cleaned out my shed of a bunch of
Gravely stuff that "I might need". Parted out a tractor, or 2.
Whenever I put a wrench to one of those machines, I'm impressed. Built
to last and they do.

The pinion gears are machined steel, but the ring cears are cast iron
- with no machining of the gear teeth. ...

That I haven't seen. Every Gravely gear that I've seen had machined teeth.

Bob

wrote:
By the picture, there appears to be pitting only on the non-pressure
side of the gears. ...

That gear, and all the others that have rust, are only rusted on one
side. But I don't if it's the pressure side or not. I could figure it
out but I really don't need to know.

The tiller only works in one direction, ...

Actually, it does have a reverse gear, but the one pictured always turns
the same way.

Bob

On 2008-01-15, Bob Engelhardt wrote:
Mark Dunning wrote:
Have you tried the Electrolytic method of de-rusting?
...

Yes, I have. I prefer acid: it's much faster; electrolytic leaves a
really awful gunky residue; the length of the current path affects the
derusting.

I also prefer acid.

i

Gunner wrote:

On Mon, 14 Jan 2008 02:40:36 -0500, "Michael A. Terrell"
wrote:

Gunner, have you ever used a variable DC power supply and an ink
eraser to polish a worn commutator? I've done it to hundreds of vacuum
cleaner motors, as well as power tools. I connect the motor to the
power supply, then bring the voltage up slowly till the motor is
turning, slowly. Then I use the ink eraser to polish the copper
segments.

No, I've not. Works well I take it?


I made $5-$10 every time I did it. The vacuum cleaner guy kept
asking to see my "Armature Lathe', so he couldn't tell the difference.


http://www.officedepot.com/a/products/930032/Paper-Pen-Pencil-Eraser/
is the erasers I used to use, but back then, they were only 25 cents.

I used a modified Exacto knife blade to undercut the mica between the
copper armature segments. Part of the point was ground down to let me
hold it at a better angle, without damaging the edges of the copper
segments.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

On Mon, 14 Jan 2008 21:29:50 -0500, Bob Engelhardt
wrote:
Dave Hinz wrote:

I'd run it as is. ...

Can't do that - it's bound up with rust. Minimum of breaking it down,
cleaning off REALLY heavy grease, removing rust, & reassembly. That's
the time I didn't want to waste if it was a lost cause.

Get it all broken down and cleaned up before you make your Final
Decision. Or go buy any replacement parts. You don't want to be
putting it back together and THEN find the cracked Pinkney Flange.

When it blows, I don't think it'll be from pits on the gears.

That seems to be the consensus, so I'm gonna do it.

The gears are one thing, they'll run and bed in with each other if a
bit rough if kept well greased. After the 'second break in' clean the
gearbox out thoroughly and regrease.

But the bearings are quite another matter - that can cause a self-
destruct that wrecks the gearbox housing and lunches all the remaining
good bits. Take it all apart and clean it up, then go find some
replacement bearings. Don't spend a wad on ultra-precision ABEC Class
4 Zillion tailstock class bearings, just get something that works.
Then put it back together and use it.

-- Bruce --

On Mon, 14 Jan 2008 21:41:37 -0500, Bob Engelhardt
wrote:

Gunner wrote:
I just "fixed" an elderly Milwaukee right angle Hole Hawg. ...
the reduction gears and bearings were rusted into an amorphous mass. ...
All them needle bearings...mass of rust. ...

Wow - you didn't rehab that drill, you resurrected it! It was dead and
rotting and now it lives! And who would re-use rusted needle bearings?
You're an inspiration, Gunner. I have a rusted needle bearing in this
rototiller - I guess I'll re-use it. Well, maybe not.

Bob


Chuckle..with the PBlaster...some heat, some pressure, some
vibration..the bearings will either wipe out totally and not even act
as bushings..or start to turn.

Ive got $0 in it.

The drill was designed to hog screwtipped auger bits through headers
and 2x4s and beams at slow speeds. Its a beast. Now instead of a dead
piece of ****..its a noisy but running piece of ****.

Good enough.

I do industrial electrical among many other things. Not a lot of beams
and whatnot in tilt up buildings. So if I use it 2x a year...2
holes...its...

Good enough


Gunner

"Michael A. Terrell" wrote in message
...
Gunner wrote:

On Mon, 14 Jan 2008 02:40:36 -0500, "Michael A. Terrell"
wrote:

Gunner, have you ever used a variable DC power supply and an ink
eraser to polish a worn commutator? I've done it to hundreds of vacuum
cleaner motors, as well as power tools. I connect the motor to the
power supply, then bring the voltage up slowly till the motor is
turning, slowly. Then I use the ink eraser to polish the copper
segments.

No, I've not. Works well I take it?


I made $5-$10 every time I did it. The vacuum cleaner guy kept
asking to see my "Armature Lathe', so he couldn't tell the difference.


http://www.officedepot.com/a/products/930032/Paper-Pen-Pencil-Eraser/
is the erasers I used to use, but back then, they were only 25 cents.

I used a modified Exacto knife blade to undercut the mica between the
copper armature segments. Part of the point was ground down to let me
hold it at a better angle, without damaging the edges of the copper
segments.

Turning down armatures and overhauling DC motors is the one paying job I've
ever done on my lathe. It was a real specialty -- old high-speed Mitchell
16mm movie cameras. I did one for a guy as a favor, he told his
camera-collector friends, and pretty soon I was getting mail from around the
country asking me to do them.

--
Ed Huntress

On Jan 14, 9:55*pm, Bob Engelhardt wrote:
John Martin wrote:
I've got an old Gravely tractor and several gearboxes for the rotary
plow and rototiller attachments. *...

Hey, me too. *A couple of years ago I cleaned out my shed of a bunch of
Gravely stuff that "I might need". *Parted out a tractor, or 2.
Whenever I put a wrench to one of those machines, I'm impressed. *Built
to last and they do.

The pinion gears are machined steel, but the ring cears are cast iron
- with no machining of the gear teeth. *...

That I haven't seen. *Every Gravely gear that I've seen had machined teeth.

Bob

The only non-machined Gravely gear I've seen is that large ring gear
in the rotary plow/tiller banjo housing. Normally the machining is
pretty good on their parts, and they do last.

They are impressive. Used mine this morning to clear 15" of snow off
the driveway with the plow blade. Plenty of power, and runs out of
traction first. Think I'll try to find a set of dual wheel adapters.

John Martin

Bob Engelhardt wrote:
I got a rototiller at the dump. The motor is fine, but it wouldn't
shift gears. The "transmission" was a bitch to get apart, but I did it
and found rust, as I expected. I'm undecided between pitching it and
rehabbing it.

I reassembled a "gear within" hydraulic pump showing a little bit less
pitting than that, and it works just fine. You should be okay.

Best wishes,

Chris

Ignoramus5390 wrote:
On 2008-01-15, Bob Engelhardt wrote:

Mark Dunning wrote:

Have you tried the Electrolytic method of de-rusting?

...

Yes, I have. I prefer acid: it's much faster; electrolytic leaves a
really awful gunky residue; the length of the current path affects the
derusting.


I also prefer acid.

What acid do you use, Igor? I've read that the black oxide layer left by
electrolytic derusting actually sucks for painting on because it has a
significantly different coefficient of thermal expansion to that of the
steel, causing it to flake off. But I haven't put it to the test yet.

Best wishes,

Chris

Ignoramus5390 wrote:
On 2008-01-15, Bob Engelhardt wrote:

Mark Dunning wrote:

Have you tried the Electrolytic method of de-rusting?

...

Yes, I have. I prefer acid: it's much faster; electrolytic leaves a
really awful gunky residue; the length of the current path affects the
derusting.


I also prefer acid.

Also, does it dissolve the un-rusted metal too?

Chris

Michael A. Terrell wrote:
Gunner wrote:

I just "fixed" an elderly Milwaukee right angle Hole Hawg. Thing had
the power cord amputated at the handle, the trigger switch was cracked
into 2 pieces (JB Weld) and the reduction gears and bearings were
rusted into an amorphous mass. Found head down in a 5 gallon
bucket...under an eve.

I left it soaking head down..in a bucket of diesel for a couple weeks,
then hammered the gear cover off and the gears apart. All them needle
bearings...mass of rust. Wire wheeled the gears until I could see the
teeth again, soaked the head in PBlaster for another week, then
reassembled it. Sounds like a coffee can filled with #3 granite..but
since its only going to drill a few holes a year...I can live with it.
I shudder to think of what Milwaulkee will want for a complete bearing
package..and the armature needs a turning... so when it goes..it goes
into the circular file. But I figure the tired old bitch will smooth
out a little bit and then run for a few more years.

Gunner



Gunner, have you ever used a variable DC power supply and an ink
eraser to polish a worn commutator? I've done it to hundreds of vacuum
cleaner motors, as well as power tools. I connect the motor to the
power supply, then bring the voltage up slowly till the motor is
turning, slowly. Then I use the ink eraser to polish the copper
segments.

That sounds cool. Does the ink eraser just work as an abrasive, or is
there some chemical action. What chemical is in an ink eraser?

Best wishes,

Chris

On 2008-01-15, Christopher Tidy wrote:

What acid do you use, Igor?

Muriatic.

I have a jar with muriatic acid and I just put stuff into that jar to
derust.

After it is derusted, I would take the piece out, wash it with hot
water, dry it quickly (I like to put small things on the electric
kitchen range to boil water off, but no more). Then, after they cool,
I put some oil on them to prevent further rusting.

I've read that the black oxide layer left by electrolytic derusting
actually sucks for painting on because it has a significantly
different coefficient of thermal expansion to that of the steel,
causing it to flake off. But I haven't put it to the test yet.

I did not like the electrolytic derusting process, too much. Acid is
more straightforward.

i

On 2008-01-15, Christopher Tidy wrote:
Ignoramus5390 wrote:
On 2008-01-15, Bob Engelhardt wrote:

Mark Dunning wrote:

Have you tried the Electrolytic method of de-rusting?

...

Yes, I have. I prefer acid: it's much faster; electrolytic leaves a
really awful gunky residue; the length of the current path affects the
derusting.


I also prefer acid.

Also, does it dissolve the un-rusted metal too?

Chris


Yes, it does, but very slowly compared to dissolving rust. Just do not
forget to take the piece out in time.

I tried both methods (electrolytic and acid). For smaller pieces,
acid is much more straightforward. Wear eye protection etc.

i

Ignoramus25819 wrote:
On 2008-01-15, Christopher Tidy wrote:

What acid do you use, Igor?


Muriatic.

Thanks. I think that will dissolve the unrusted metal, but perhaps only
slowly. I'll have to try it sometime.

Best wishes,

Chris

Christopher Tidy wrote:

Michael A. Terrell wrote:

Gunner, have you ever used a variable DC power supply and an ink
eraser to polish a worn commutator? I've done it to hundreds of vacuum
cleaner motors, as well as power tools. I connect the motor to the
power supply, then bring the voltage up slowly till the motor is
turning, slowly. Then I use the ink eraser to polish the copper
segments.

That sounds cool. Does the ink eraser just work as an abrasive, or is
there some chemical action. What chemical is in an ink eraser?


The ink eraser is very abrasive, compared to a normal eraser. It
will even remove minor scratches from the copper. try it sometime.
Most 120 VAC universal motors will run slowly on 8-14 VDC, and the
eraser is under a buck. Keep the speed as low as possible, to keep from
getting the eraser dust between the armature and the brushes.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

Michael A. Terrell wrote:
Christopher Tidy wrote:

Michael A. Terrell wrote:

Gunner, have you ever used a variable DC power supply and an ink
eraser to polish a worn commutator? I've done it to hundreds of vacuum
cleaner motors, as well as power tools. I connect the motor to the
power supply, then bring the voltage up slowly till the motor is
turning, slowly. Then I use the ink eraser to polish the copper
segments.

That sounds cool. Does the ink eraser just work as an abrasive, or is
there some chemical action. What chemical is in an ink eraser?



The ink eraser is very abrasive, compared to a normal eraser. It
will even remove minor scratches from the copper. try it sometime.
Most 120 VAC universal motors will run slowly on 8-14 VDC, and the
eraser is under a buck. Keep the speed as low as possible, to keep from
getting the eraser dust between the armature and the brushes.

Cool idea. Sounds like you could also use Brasso, except for the shock
risk and the inconvenience of getting it inside the motor!

Chris

Christopher Tidy wrote:
What acid do you use, Igor? ...

As Iggy said - use muriatic acid, which is a low grade hydrochloric acid
(HCl). There is LOTS of info in the Google NG archives. Search RCM for
"muriatic rust".

Briefly:
- do NOT use it in the shop. The vapors WILL rust every exposed steel
surface!!!
- it is not particularly dangerous, except to the eyes. And the fumes
are very irritating to breathe.
- after derusting, rinse very well, in HOT water, and IMMEDIATELY oil.
The acid cleaned steel is very clean and will rust before your eyes
unless protected. I like to use wax - I keep a gallon can of paste wax
dissolved in paint thinner. I just dunk small parts & paint it on others.
- the acid will dissolve aluminum and zinc (galvanizing).

Bob

Bob Engelhardt wrote:
Christopher Tidy wrote:

What acid do you use, Igor? ...


As Iggy said - use muriatic acid, which is a low grade hydrochloric acid
(HCl). There is LOTS of info in the Google NG archives. Search RCM for
"muriatic rust".

Briefly:
- do NOT use it in the shop. The vapors WILL rust every exposed steel
surface!!!
- it is not particularly dangerous, except to the eyes. And the fumes
are very irritating to breathe.

Second That!
Please stay upwind of your project. If you don't, you will very much wish you had.
DAMHIKT

The acid I used for removing galvanize liberated heat and bubbles in use. I was pleased
to be wearing eye protection at the time.

--Winston