Bakelite pulley disaster...ideas wanted.

Dranreb said:
Hi Paul, the pulley is 4 1/4" diameter.

Will look into getting bakelite, didn't know it was still available.

Great idea the Tufnol, just remembered I've got a piece of stuff that might be just right, it is a coppery colour with a linen looking surface is that Tufnel?

Dug it out and its big enough get two centers out of, and two smaller bits fro the boss in the middle, I could screw it all together and turn it to shape.

What's wrong with the dust?

Bernard
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The dust is carcenogenic as far as I am aware. Tufnol is the coppery stuff and is a good material to work with if you control the dust. Just keep it wet as you use it and it will mitigate the dust. It's pretty common practice to to use a tufnol gear in the gear train of lathes and mills. This creates a weak link if you crash the machine, sacrificing the tufnol gear instead of all the gears. My Emco Maximat also had tufnol gears in the headstock and was extremely quiet while operating. It's great stuff and will likely be a good option for the centers and boss you need to make.

Paul.
 
I think 6 brass round spokes would look realy cool. Not sure if that is an option cause it wouldn't look original at all.
Thread in to the center flats ...tread opposite end and made custom spoke nipples that match contour of the pully.
 
Get a phenolic from McMaster-Carr supply a little bit bigger then what required
Machined the center of the phenolic to fit your hub. Epoxy the hub in place.
Put the repaired pulley up in the lathe ,turn true on a spud or on centers to the same profile as the damage sample.
Robbie
 
Wow, so many alternatives to consider, many thanks chaps, you've been a real help, spokes had briefly flickered across my mind too.....hmmm :think1:

Will let you know what I go for and post some pics of my progress.

Bernard
 
It is very nasty and If I were you I would rig up a shop-vac to the compound and suck up as much as the dust as you can and wear a respirator used for spray painting or at least a dust mask and as always wear some safety glasses or goggles. I learned early on that it makes your skin itch like fiberglass insulation does. Ventilate the area as it smells like burnt rubber and makes me sneeze. I never tried cutting it wet.
 
Well folks, it's done! grin.gif

I turned a thread on an unknownium arbor to match the 3/8" shaft thread, BSB, 26 tpi, this was my first go at threading, I nearly crashed it on the last pass, must have relaxed and forgot to pull the half-nuts at the shoulder! Just caught and scratched the top of the thread, phew...EMOASsweating001.gif a little filing and re-face the shoulder fixed it, not the best thread tool grinding in the world but OK for the need.

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Well after messing about with turning the Tufnol to fit the brass hub, which went well and was good practice until I realized that I had got oil soaked into it so the adhesive wouldn't stick, I gave up on that and went with Acetol.

First problem was the very old BSP tap I that luckily came with a load of clutter I scrounged years ago, it was actually 25.5 tpi and jammed in the brass center! Very shoddy manufacturing, and can't blame the Chinese for this one, probably 60 yrs old! No way I was attempting internal threading, and neither of my retired machinists neighbors had one in there vast tap collections, so I used it and as only half the tap length was needed I hoped the Acetol would be flexible enough, and it is.

Got hold of some black Acetol, a little more flexible that Delrin apparently, but lovely to machine, got a bit tricky trying to turn the crown in between the flanges and I took a little too much off so effective diameter is a wee little bit smaller.

Had a few problems with chatter marks (this was quite pretty, and I noticed the original pulley suffered the same problem) when hogging out and finishing each side of the thinner part, I cured this by placing the old pulley rim against the chuck jaws behind the new one, it stayed in place without fixing.

Learned a lot about grinding special tools and also learned to quite dislike my lantern and four way tool holders because of the constant hieght re-setting.

Ordered a QCTP that arrives tomorrow, decided a wedge type would be a waste of money due to the limitations of my Atlas compound and cross slide,

http://www.arceurotrade.co.uk/reviews/MEW176_p022_25.pdf

http://www.arceurotrade.co.uk/Catalogue/Machines-Accessories/Lathe-Accessories/Tool-Posts I got the model 100

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Thanks for all your guidance, which is much appreciated. :thumbzup:

Bernard

EMOASsweating001.gif DSCF7697.JPG DSCF7699.JPG grin.gif
 
OldMachinist said:
Looks good.

Sounds like that tap has a 1 mm pitch which would be 25.4 TPI.
Click to expand...

I can see why you would think that OM, and it makes sense but 1mm thread gauge does not fit either....

As you can see in this pic both taps are stamped 26, yet the 3/8" one is approx 26.5 ish or somewhere thereabouts, while although the pic can't show the difference the 1/2" one is correct, BSB http://www.britishfasteners.com/threads/bsb.html .

The collective conclusion here (one machinist, one design engineer, one toolmaker and me, all retired) is that the tap is of shoddy manufacture..

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Gotta go...new QCTP just arrived..:ups:

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