Bridgeport drive belt size?

[Taris JewellParticipant @tarisjewell61133]

Hi so I’m after some advice i am trying to replace the belts in my Bridgeport but I’m not sure what size the belt should be.
the issue I was having is the speed adjuster felt like I had to take up the backlash in it before changing speed, so I thought it would need a new belt. so I stripped it down and found the belt didn’t look bad but a load of belt dust so I ordered a drive belt and timing belt.
my machine
Its an Adcock Shipley Bridgeport (UK-built) with a 2J head and a 2 hp motor. I believe it was built in the late 60s to early 70s like 68-71 but not too sure.
the problem I have is the old belt is marked 1-18-2120 2j668 flexten so I ordered a belt with that number, but when it turned up it was too short. so I took some measurements. The OG belt is 36mm wide by 900mm long, the new belt is 38mm wide by 875 long, which seems to be the US size that I have found online. I believe that the change in thickness is down to where but I don’t believe it would stretch that much and still look usable.
the company that sold me the belt said that it might be because it is a UK machine and that might be different from the US size.
they have sent me another belt that is 38 by 900 that they have listed for a 3 Hp machine but I’m not sure what to do?

[Andrew JohnstonParticipant @andrewjohnston13878]

Could try these people:

Bridgeport spares

Andrew

[Clive FosterParticipant @clivefoster55965]

The “take up the backlash before changing speed” issue isn’t a belt problem.

Its mechanical. Something interfering with the fee movement of the sliding varidrive pulleys.

Due to the design with the adjuster on the front pulley and strong spring on the motor pulley the drive is largely self compensating for any belt wear. Worn belt means the speeds will be out. But the dial is more indicative than accurate. The speed error will be too much to accept long before the belt is worn past driving.

But everything must move freely. You’d think that the monster spring would easily overcome any stiction in the pulley movement but in fact it doesn’t take much to interfere with things.

Check that the key in the motor pulley is still correctly screwed on. Mine came unscrewed leading to interesting noises and iffy speed selection. But it still ran sort of OK despite only driving via one side of the motor pulley.

Something similar with mine when I first tried to put it into service. Bushes in the front pulleys were pretty much toasted and the motor pulley didn’t seem to move well when shifting by hand after removing the spring.

Mine had the old style formed in place turquoise coloured bushes on the front pulley so I couldn’t just buy new bushes. Boring out the old bush material and making replacements was an education in thin wall turning of delrin. Second try was the charm!

If 20 year old memory is correct I found some drive key issues with the motor pulley as well as the usual corrosion and crap in the sliding surfaces to be expected from something that apparently hadn’t been touched for 20 years. Not helped by previous owner leaving the machine out in the rain. Head was seized so I had words with the dealer who sold it to me and managed to get my parts paid for. Pretty sure he never tested it, just turned it round cheap on E-Bay. Properly lubricated and re-assembled its run fine ever since except for when the key on the motor pullet came loose, as mentioned above. That key is held in place by two small screws. Loctite advised.

Clive

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