On Sat, 3 Dec 2005 22:45:37 +0000 (UTC), Christopher Tidy
wrote:

I spent more time testing the drill today. As the brushes won't come
out, I removed the plastic caps and connected a multimeter to the
brushes. With the magnet energised a voltage of 80-140 V AC appears
across the motor. The voltage varies with the position of the speed
control knob as one one expect. So there is clearly a problem with the
brushes as Wayne suggested, but whether the armature and field coils are
okay, I don't know. All I can say is that they don't smell or look burnt.

One possibility is that the brushes got so short that they cocked in
the housing some. I've also seen them wear a little lip on the end
when worn down pretty far.

The magnet still seems weak. Although it isn't really weak, I wouldn't
have great confidence using the machine for vertical or overhead work. I
arranged a test to give me some idea of the magnet's holding strength. I
attached it to a piece of 1" thick steel, with the magnetic base
vertical and the drill body just above the ground, and stacked some
weights on the side. Then I took moments to figure out the holding
strength. It is about 1/4 to 1/3 the 1740 lb quoted on the Hougen
website for a 1" thick plate. I think there could be a problem here, but
I'm not absolutely sure. What do people think?

Well the strength quoted is on absolutely smooth and clean metal. In
other words a piece of precision ground stock. Any imperfections
reduce this number and in a hurry. I just got through using my
Milwaukee mag drill and since it was on about 1/4" stock with paint
the magnet didn't hold much at all. But it has a nice ledge that's
easy to c-clamp which I did use. On the other hand if I have it on a
nice thick piece that's really clean I do have to lean into it a good
bit before pushing it over side ways. Mine is rated at 1640lbs drill
point pressure for a comparison. You can find it here.

http://www.milwaukeeconnect.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=27&catalogId=40027&langId=-1&productId=284338&mainHeader=Tools&categoryId=189 341&mainCategoryId=362&parentProd=281164


I've not looked at there site but it's possible they're quoting
straight pull of strength and peeling off side ways like that isn't a
good test. Yes you can calculate it somewhat but also be aware that
only a small portion of the magnet is holding for that type of
peeling. The main portion doesn't have the leverage.


I had a response from the seller this morning. He said he had the drill
tested for him using an appropriate transformer. I didn't mention
transformers in my e-mail to him. He seemed puzzled but not indignant. I
will tell him what I discovered today.


Sounds like a good move.

Wayne Cook
Shamrock, TX
http://members.dslextreme.com/users/waynecook/index.htm