Sorry, this is a bit longish?
My Bridgy has a rattly head. Its not a Vari-speed, just the common or
garden variety J-head with a 2-speeder on it.
I finally got some time to myself this afternoon, and wired up the
phase converter so I could start it up and see what I had bought. I'd
already noticed a little wear in the slides but nothing to really
worry about, but obviously couldn't check much else without power on.
The DRO worked fine straight away, so that was a plus as I was
expecting the worst. Set the drive up in low range, flicked
everything on to start up the motor, switched to the first speed and
bingo, I had a rotating spindle. Power downfeed worked as well so
that's another plus. There was a wee bit of a rattle, so switched
motor off, changed the belt up two steps and switched on again, still
in low range/backgear. Starts up fine again, but got even more of a
rattle. Changed into high range, switched on, the motor ramped up to
speed rather slowly and then the head produced an almighty clatter
(well maybe not almighty, but you know what I mean?).
Switched off again, let the motor coast to a stop, switched the motor
to high speed and pushed the start button. Well the converter didn't
like this at all, only showing about 230V on the meter (previously the
voltmeter was steady at 415V) and not getting the motor anywhere near
speed. Switched off, set the boost switch on the converter from 2 all
the way up to 8, and tried again. Same thing happened, 230V on the
meter, spindle running dead slow, then the overload on the contactor
tripped out and knocked the motor off. I did notice that the 'boost'
light on the converter didn't come on at any time so I may have a
problem here as well.
Feeling ambitious I thought I'd strip the top of the head down to look
for anything obvious. Took off the motor, then the belt housing, then
the backgear/clutch housing. Took off the sensitive feed handle and
clock spring and was about to drop the spindle but for some reason
decided not to. I couldn't detect any play in the spindle bearings
from pulling the splined drive shaft in all directions, and couldn't
hear or feel any noise or harshness so left this bit well alone.
The motor pulley appeared OK too, again no obvious bearing problems.
The driven (spindle) pulley made a little noise when being spun by
hand, but nothing remotely like I'd heard earlier. The backgear
housing was the same, but I couldn't find my puller to remove the
timing pulley (my little garage is fast approaching the minimal floor
space ethos as promoted by John S ) so I didn't get this apart any
further. However, I have a suspicion that the rattle is originating
Anyway, I cleaned it up a bit and put it all back together and started
the motor up again. I must have done something as the rattle in low
speed backgear is now almost gone, but unfortunately is still bad in
higher backgeared/low range speed and unacceptable in all high range
speeds (still on 1st motor speed setting). I noticed that if I put
some tension into the drive by holding the spindle nose with a rag
whilst it is spinning the rattle disappears completely. It definitely
seems to be coming from the backgear/clutch area.
So, anyone have an idea what this could be, and what I should be
looking for or doing to try and fix it?
And secondly, is the rather slow ramp up on the static phase
converter(3KW) normal, or is the lack of a 'boost' light indicating
that this is faulty too?
My brothers Bridgeport displayed a similar noise until it seized and what he
found was the drive belt had split across the belt in several places and was
trying to pretend it was a toothed belt. £54 pounds later new belt fitted
and problem gone.
Mine made some God awful noise from the head under power when the
splined drive just below the timing belt in the back gear wasn't
engaging/disengaging properly. Can't remember how I fixed it but it
was only time - no money needed.
BTW in my limited experience the timing pulley can be a bugger to get
off without damaging it. And don't damage the timing belt either. It's
non-standard pitch that costs about £40 from Bridgeport.
Also I replaced the main vee belt with a link type and have had no
problems. I know the books say they are uni-directional but it works
just fine for me.
Our Japanese Ashina (built in Hiroshima, glows in the dark....) bench drill does
something similar, it is the quill rattling dry inside the spindle. Not a
problem at low speeds or under load, might be worth trying to get some lubricant
down the splines and seeing if that gives any improvement.
Peter & Rita Forbes
It's the cam at the top .
it has two pegs that come loose
the cam raises and lowers the drive to engage low or high
when these pins work loose .
it's not in either range properly
it will rattle in one speed
and stall in the other.
see my thread here on how to fix the problem if the threads are
Now Mark has given the details that was the same problem that I
suffered - and the same cure.
Of course since I've remotored it and use an inverter back gear
doesn't see much use.
On the convertor front try running a slave motor first and then
switching on the Bridgy. A 1hp motor might be enough. That way you've
just turned it into a rotary convertor.
It might also help to quieten the head down, as you'll be getting
hopefully closer to a true 3-phase supply and thus a smoother running
Traditional & Modern canal craft repairs
Vintage diesel engine service
Thanks for all the information and ideas. I have now found the problem
after the 3rd head strip and fixed one part of it, fixing the second
part will cost a little bit.
Backgeared low range is now nice & quiet on all speeds, the problem
appeared to be that it wasn't fully clearing the dogs from direct
drive on this range. The cam pins were actually OK, but the linear
movement of the driven pulley back into the housing was a bit
sticky,probably due to a small bit of wear in the housing allowing it
to cock over very slightly.
The fix here was to preload the 4 small springs under the pulley. As
luck would have M4 cap screws are a perfect fit inside the spring. I
turned the heads down to reduce the height to around 0.100" and cut
the threaded length down to leave a short stub inside the spring and
refitted them. The extra preload now lets it move straight back
without cocking and disengage sweetly.
The high range noise is still as bad as ever and this is down to wear
in the dog clutches. The wear is very bad on the backgear dog with a
stepped ridge all the way down to aboout 0.010" off the bottom. The
dogs on the pulley side are not as bad but are rounded over on the
corners on one edge, probably because it wasn't disengaging properly,
and this looks like it has been replaced some time in the past,
perhaps in a half-hearted effort to cure the rattle.
So, new dog clutches and probably bearings whilst I'm at are the order
of the day. Chequebook time again dammit!!, although I can't really
complain considering how little I paid for it.
I've managed to fix both the previous issues on the Bridgy now, and
finally had it all working today.
The noise was cured by fitting new dog clutches for the high-range
drive. As I mentioned before the old ones were pretty severely worn,
and if you think yours may be worn then you can test for this by
grabbing the spindle nose with it set in high range and twisting it
back and forth. If you get a bit of play or backlash, then it is the
engagement of the dog clutch, caused either by wear in the dogs or if
you're lucky the cam pins.
I managed to get a (practically new) spindle pulley hub from DCMT in
Ardleigh for a contribution to the maintenance workers Christmas Party
Fund. Unfortunately I had the buy the other part, the splined gear-key
hub from Bridgeport (££ouch!). For anyone with a similar problem these
are items 20 & 57 in the J-head top housing section of the manual.
Fitting them was even more fun. Whilst I had them out I decided to fit
new bearings in the spindle pulley sleeve as the originals were
notchy. These are held in place by two threaded collars which were so
tight it took a hammer and pin punch to undo them, tapping them round
a faction of a turn at a time. There were no obvious dings anywhere on
the internal or external threads, but even after a quick wiz through
the U/S cleaner they wouldn't go back together more than a few turns.
I bought a rather neat thread restoring file from e-bay to dress them
up. Although I've used these many years ago I hadn't seen one like
this before, and it had a short extra section on the end with the file
teeth perpendicular to the axis so that internal threads can be
cleaned up with it, rather than just external. Made by Sherwood tools
in Leicester, very useful. Anyway, after using the file both sets of
collars screwed in and out without binding.
For reference the large collar is 20 TPI and the small one is 18 TPI,
The bearings are cheap, about a fiver each from BSL, and are SKF 6207
ZZ. The only difference from the original bearings was that these are
sealed on both faces rather than just one. The bearing in the backgear
where the splined gear-key hub fitted was fine, so I just popped the
new hub in and put it all back together.
Now time to fix the converter. I had phoned Power Capacitors at the
beginning of the week and explained what was happening. They didn't
seem surprised and explained that the voltage sensing relay that fits
into a socket on the back of the front panel can sometimes come loose
in transit and just needs plugging back in. If it was plugged in then
the relay was faulty and they could then send out a new one.
I pulled the front panel and lo and behold it was missing from the
socket. What was even more surprising was that it hadn't just fallen
off, it hadn't even been fitted in the first place and was nowhere to
be found! Without this it can't switch the contactor in or out and
pull in the capacitors, so it was a wonder it even ran the Bridgy in
the first place:
A new relay was sent out next day, and I fitted this back into the
convertor after I'd had the head back together.
I set the Bridgy up in high range, pulley speed at 920 rpm and pressed
the start button - hurrah! no nasty rattles anymore and up to speed
immediately. I then tried it at full speed (4600) to see what the
converter would do. With the boost level set at 1 it struggled a bit
to get it going, but upping this to level 5 out of 8 started it
So there it is all done, and I can use it at last. There is still a
very slight tick in the drive somewhere, a small 'single point
catching something' sound, but I want to use it for few jobs first
before I look at it again.
I know this thread dates back a long way, but powering a Bridgeport from
a phase convertor is something I've wondered about doing myself. The
phase convertor is one of my current projects; the Bridgeport is further
off *dream*. Do you know what the output power rating of your convertor
is, and also what size of idler motor it uses (if it has one)?