Sparking motor

Hey all! I have a century brush start induction repulsion motor on my c+p. It started sparking. I opened it up cleaned some grime & grease off it & have been able to keep going. More recently it started sparking & smelling chemically. I checked to see where the Sparks where coming from & it was from the brushes. We took the brushes that had the issue out & wiped them down, put them back. Still sparked so we raised the brushes a little to prevent sparking. It seemed to work. Now the other brushes have started sparking & the motor has slowed down. I’ve tried adjusting how much the brushes make contact & it will work for a little while. One set of brushes is getting worn down. Any suggestions? Is there something I can do to fix it? Is it time for a new one? Of course these issues happen when I’m knee deep in my 4th quarter printing & planning.
Any insight is most appreciated. Thanks!

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First, I’d check that the press is properly lubricated and that nothing is binding. Excessive load will draw more current and cause more arcing.

If the press is running smoothly, I’d take the motor to a shop. The armature may need turning, or there may be more serious issues.

The brushes run in contact with the commutator which transfers current to the armature. If the commutator bars are worn or if the spaces between them have filled with carbon dust from the brushes or copper particles rubbed off the commutator, that can cause both the arcing and the slowing down of the motor. Best to get it to a motor repair shop, as they can often turn the commutator a little and clean out the gaps between the bars and make it like new.

If there is a removable cover over that part of the motor and you can get access to the commutator, you may be able to carefully (with power disconnected!) scrape out the gaps and with a fine emery cloth polish the surface of the bars if they aren’t scored or otherwise damaged, then blow all the residue out, and get by for a while.


Ramblings from Afar. . . If it is not possible or practical to INITIALLY remove the motor for inspection and appraisal, few little pointers to look for, before *Biting the Bullet* may give your Motor factors something to go on.!
The following are just generalisations:- 2 sorts of brush holders , (A) the type that are conductors in their own right and carry the brushes (carbon) without braided Tails into the windings via Paxolin or similar back plates
(B) The brushes are carried in isolated/insulated holders and have Copper braided tails going into the internal windings, The field Coils or the Stator normally.

Again, generally, the brushes are held in contact with the Commutator /Armature with very precise pen steel springs which can usually be observed, have a precise depth limit factored in to stop them (the springs) contacting and damaging the armature if/when the carbon gives out.
Invariably if/when the limit is reached and there is not enough carbon left, arcing begins and apart from the visual there is a quite distinctive smell.!!

If it suspected that either the Armature/Commutator or the Field coils have begun to break down, look in/inspect any other, known to be in good order, Motor and compare the colour of the windings, should be a nice even overall Shellac/Copper colour
If either or both are breaking down, their will be very distinctive *blue* discolouring.
Close inspection of the Armature may well show, where the individual windings terminate on the segements of the commutator and overheating has begun to occur, it shows up as solder being *thrown* from the connections.???

Inspection of the actual commutator may also show that over the course of time, the commutator has worn down with a distinctive *Tram Line*
This can be Turned Down, up to a point, but only to the limits of the width of the brushes.!!!

As the brushes have possibly been removed, have they been replaced in the original orientation,??

Generally new or replacement brushes are square on the approach to the commutator and automatically Bed In.
but in so doing, by default causing feathering off, on the trailing edge, by implication can be reversed 180 degrees, that will cause arcing for a while.!!

Thanks so much, AnonyMouse. The press moves freely & all is well lubricated.

It does seem to have carbon dust AdLibPress. I’ll see if I can carefully remove as much as possible.

And Mick on Momotype, thanks for all the pointers. I definitely have the brushes with the braided tails. I’m going to take a closer look tomorrow with all your info printed & in hand to compare.

Thanks again everyone! I appreciate you taking the time to share.

don’t know your location, but here, we have a good motor re-builder, and access to brushes. if not on the shelf, custom made

Afavorite, Thank You for the *Nod* . . My efforts were only intended as pointers/clues for passing on to your experts, before dismantling and or removal, if it comes to that !!
However if you feel like advancing the situation without going *too deep* and again generally? even when Armatures here have to be turned down to remove the “steps” there is no special purpose tool to clean out the accumulated carbon dust/copper swarf etc.

Even the professional Engineers may specify on the final bill >To Turning, Under cutting Etc Etc< 90% of the time The undercutting/deburring tool, is one of 2 possibility`s (a) an ordinary High Speed hacksaw blade, carefully ground with a small hook configuration, (either like “Grannies” Crochet Needle or a Fish Hook without the Barb.)

Generally the hacksaw blade is virtually a perfect fit to clean out between the segments, INCLUDING & Especially into the Gaps where the copper segments are intersected by the soldered windings.


(b) One other excellent option for this operation is a Traditional Dentists Stainless Steel tooth pick, the type that has a tiny spade at the point, just ground down to the exact width of the gaps on the commutator, the precise width taken from the unadulterated/undamaged section, 1/8” (ish) normally seen beyond the reach of the brushes at the Outer end of the Com.!

One more little device that is employed, if /when the commutator has been cleaned out, it is almost inevitable that tiny whiskers of copper are left proud on the segments.
We just make a tiny linishing tool, i.e. finest grade Wet & Dry stuck to a length of Pica/Wood furniture, held against the commutator whilst the armature is turned by hand, works really well.

We occasionally use a tiny amount of liquid metal polish on the wet and dry, to achieve the best possible finish, but also tiny amount of dried out polish acts as a very, very gentle Lapping agent to re-bed the brushes.

All the foregoing offered as just possibilities, NOT as alternatives to Qualified Expertise, unless we are flying on *A wing and a Prayer*

Good Luck.

ericm I’m in Chicago. Where’s your person?

Good news! I hit two motor places today for brushes. The second had something close but not quite. The guy that helped me was kind & sanded them down to fit. How nice is that!?! Very grateful.
And thank you briar press peeps for all the help!
Especially Mick on Monotype. I was able to clean the old carbon off with the suggested dental pick. Worked like a charm. Thank you, thank you, thank you! I’m thinking next time I head out of town I’ll set up a appointment & drop it off for a good check & make sure all is well. Until then, I best get back to printing.
Thanks again everyone!

Afavorite,,,, BEARS Eh???? well i am up here in PACKER LAND>>> Milwaukee,,,,
contact me offsite, and i will be glad to help if i can….

ericm, i may live in chicago but i ain’t no bears fan.