Thread: I learned two things today...

I also learned 2 things.

Firstly is - warming up ur 2 pack epoxy resin is a great way to make it more brushable...

Second thing I learned is - epoxy, once warmed, sets rock hard in about 1 minute, & it melts the disposable plastic cup that I had it in!

Originally Posted by grd

My guess of worn brushes was correct, so after a few minutes work cutting down an old pair of washing machine brushes (see, I knew they'd be worth keeping when I replaced them 5 years ago) I now have a new saw to complement the larger 9 1/4" Triton I already have (it's really too big for most of the stuff I do).

Graeme

Hi Graeme,

While there's a chance that the material the brushes are made from is similar, there's more of a chance that it's not. While the saw was free, it would be a shame to damage the commutator for the sake of a few bucks. Just my $0.02 anyway

How did you "cut" the carbon brush to size?

Originally Posted by Anodyne

How did you "cut" the carbon brush to size?

I just scraped/cut it roughly to size with a sharp knife then fine tuned it with a small file. The graphite is harder than your typical pencil lead, but the principle is the same. I've done this a few times over the years as I always seem to need them for motors which nobody stocks brushes for, so I just buy a slightly bigger set, trim them down (brush and lead) and resolder the relevant connector on the other end.

Tools4Me - Yep, that did cross my mind and I had planned on getting the correct brushes, but the saw has clearly been run for a long time with severely worn brushes. When I first tested it there was an impressive display of arcing on the commutator. One of the brushes was worn enough to expose the copper lead and the commutator is pitted and scarred. If I had a lathe I'd shave a little off to smooth it, but as it is I'll stick with the *slightly* harder ex-washing machine brushes and keep an eye on it for the moment (the harder brushes *might* polish out some of the existing damage). The saw will only see a small amount of use, so I don't expect any damage to appear without ample warning if I check it every so often. In the meantime (and that can stretch out for years) I'll probably keep an eye out for the correct brushes whenever I'm in the right place as they should only be a few dollars.


Graeme

With the commutator (bit the brushes run on) , if you can spin this in a battery drill at low speed ,use some fine 600# w&d , to clean the commutator , then reassemble the motor, once the brushes bed in , you should be right,.

Jeff
vk4

Originally Posted by grd

........
The second thing I learned? Well, it seems that sitting on the end of the bed and cutting carbon brushes down to size is not an acceptable practice. Actually, make that three things. Testing the saw in the same place doesn't win you brownie points either.

Graeme

Four things, actually, Graeme.

You broke the Eleventh Commandment!

Cheers

Graeme

Originally Posted by vk4

With the commutator (bit the brushes run on) , if you can spin this in a battery drill at low speed ,use some fine 600# w&d , to clean the commutator , then reassemble the motor, once the brushes bed in , you should be right,.

Jeff
vk4

Cheers Jeff, I'll give that a go. Now, where did I put my battery drill? Oh yes, bedside table. Silly me for forgetting that.

Graeme

Do not be too aggressive cleaning the commutator, just a light clean up.

also if you have a bench grinder , set the rest at right angles to the wheel , and just touch the brush to the moving wheel.

This will radius the brush, and improve the contact area, .

I used to make Carbon Brushes for electrical tools .

.

Jeff
vk4

I've cut brushes to size by rubbing them along a fine hacksaw blade.

And never bring your new chainsaw home in it's box and assemble it on the lounge floor if SWMBO is having a girlfriend over who is delicate and doesn't like sharp things. It was only a 20" bar.