Boss 6 Z-Axis Pulley Identification / Problem

[snakebit95]

Hey Guys,
I am getting further into my Boss retrofit, and noticed my Z-Axis pulley looked much different than the X & Y axes. I think this is a hack-job by the previous owner. The teeth actually look like they were machined, instead of cast like the others. Take a look at the photos and see if they look anything like your Z-Axis pulley. If yours is different than the photos, perhaps you could share a photo of yours??

Forgot to mention......the entire pulley is aluminum with the exception of the thin steel ring that is screwed in-place.

Thanks in advance,
Wayne

[Hood]

Wayne
The teeth on yours look like they are very very worn, apart from that it looks to be the right pulley. If I remember I will take a pic of mine today and post tonight.

Hood

[snakebit95]

Hey Hood,
So you actually think this could be wear? Wow!! If it had been modified / machined, I was wondering how the last hacker machined into the corners of the teeth. Wear certainly expains it much better; but I would have never imagined it wearing that much. What does the small bolt-on stem do on the bottom? I would have thought it provided additional support, but my machine did not have any type of bearing for it to ride-in. It just protruded through the cover housing hole, and seems it was just along for the ride.

On a side note, I searched pretty hard for a replacement yesterday. I called Hardinge/Bridgeport and all the pulley manufacturers I could find (Martin, Browning, Polytech, CMT, e.t.c.). None of them offered an H-type 13-tooth pulley. However, I found (3) different places that offered H-type 13-tooth timing gear stock. I am guessing I will probably end-up machining my own pulley from some stock. Perhaps I will make this pulley from steel this time. What do you think?? Steel or aluminum?? (since I found both).

Thanks again!!

[machintek]

That bolt on stem took a small position dial, like a miniature version of what is on the end of a S1STD mill. The belt cover had a pointer rivited to it.

George

[snakebit95]

That is great to know about the dial. I can't think of a reason why I might need it. If my machine had a digital readout, what was it's use back in the time?

[Hood]

I suppose it was used as a counter, sort of like the counters on X and Y axis.
I forgot to take my cam today but I would say that it is most definitely wear, why so much I dont know but the teeth should be the full width all the way down. I have a pic taken a while back, its not very clear as I had to zoom in, but you can just make out what the teeth are like
I would probably go for the Alu, just because thats what Bridgeport used, but the steel would probably be easier to obtain a finish on.

Hood

[snakebit95]

That picture is good enough for me to know it is time for a new gear - LOL. I am probably going to make it from steel, to keep from making it again some day. Thanks again for the photo!!

On a side note, I finished the X & Y axis adapters and mounted the servos this morning. Now I need to get busy on the Z motor mount.

[Hood]

Did you make up extensions for the motors?


Hood

[snakebit95]

Originally Posted by Hood Did you make up extensions for the motors? Hood

YES, it worked like a charm. I bored the stock pulley's out to 1", and made some 1" O.D. X 1/2" I.D. steel adapter sleeves. I used a couple 1/4" set-screws to attach the sleeve to the motor-shaft, and one 3/8" set screw to attach the pulley to the sleeve. I oriented the set-screws by 180° to offset the small amount of slip-fit clearance. When I was finished, each of the pulley's turn true within .001"-.0015" total. Pretty good, considering what they measured stock. When I indicated the teeth to the stock 5/8" bore during the boring operation, there was .005"-.008" runout; which had to be the way Bridgeport made them in production. Thanks again for the recommendation!!

[Hood]

No problem, was just the easiest way I could see to do it and it works fine for me.
Hope you get the Z pulley sorted soon, was just thinking though if you have not made up the extension for your Z you could maybe buy stock long enough to have the extension as part of the pulley itself, would save a lot of hassle.
Hood

[snakebit95]

I was already thinking about that!! I will machine a 1-piece pulley that fits my 1/2" motor shaft.

I finished assembling the head today, and have a problem with the variable speed adjustment. When I apply air to the cylinder, the air cylinder runs, and the worm-gear turns; but the shaft/dial/chain does not turn. Do you know if there is suppose to be a drive-pin on the dial-shaft? Something has to be there to drive the dial, and I could not find it. It was getting hot outside this morning, so I stopped at that point. I will look closer tomorrow morning. I bet something is sheared-off. Wish I had a shop with A/C in it.

[Hood]

Wayne, have attached a pic out of my manual Bridgeport book. I think the setup is exactly the same on the CNC Bridgeports except for the handwheel. Hope it helps.
Hood