Machining Drums and Discs - any advice

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andyd

andyd

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Trying to turn down rear drum sprockets to fit a 520 and front discs to clean them up.
Anyone have any inputs on tool bits and feed rates? Tried hss and carbide bits and asstd speeds - having issues with chatter and poor cutting. Front disc is also an issue due to chrome finish and chatter. I could try milling but it may not be easier or quicker. I have a brake lathe that has not ben used for many years, but not yet thought of using it as I'm thinking that will not improve matters.
Cheers,
Andy
 
Sorry I'm not a tool maker just a tinkerer so hopefully someone who knows will hopefully chime in
But maybe try a tool post grinder for the sprocket?
I cheat sometimes and use an air die grinder in the tool post on my lathe when I come up against something really hard
 
For the disk, you might want to find an automotive place that does Blanchard grinding. It is also used on flywheels.

www.accessnorton.com

Disc Grinding

Found a shop that does blanchard grinding. What is minimum safe thickness disc can be ground to?
www.accessnorton.com www.accessnorton.com
 
baz said:
Sorry I'm not a tool maker just a tinkerer so hopefully someone who knows will hopefully chime in
But maybe try a tool post grinder for the sprocket?
I cheat sometimes and use an air die grinder in the tool post on my lathe when I come up against something really hard
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Thought about a homemade tool post grinder but cannot use angle grinders as they spin at 10k and normal grinding wheels turn at 3 to 4 k.
Flywheel grinders would work and I may try that out, but it may then be cheaper to buy new parts.
 
Buy a new disc and be done with it, I machined my old disc down years ago and to be honest, not safe, my life is more important than to save a few $$$$, my best investment was to replace my whole front brake system with modern brakes.
As for chains I run the stock size chains, good quality chains and look after them and I get good life out of them without any problems, my last chain I got over 40k miles out of it and replaced it with a new chain from the Chainman, doing regular maintenance on your chain will give it long life all part of my service routine, pull the chain off, soak in kero, give it a good clean, fix any tight spots and soak in hot oil, all takes time but your chain will last a long time, my old chain is still good after all those miles and is hanging as a spare if need it.
 
To machine discs successfully you need to machine both sides from a double sided toolpost, this ensures the thickness is uniform.
 
ashman said:
ashman said:
Buy a new disc and be done with it, I machined my old disc down years ago and to be honest, not safe, my life is more important than to save a few $$$$, my best investment was to replace my whole front brake system with modern brakes.
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Not quite so simple. I have a box of discs that I hate to scrap and several drums. I have a Norton with a Brembo master cylinder, std disc and a Lockheed alloy caliper and it's superb, but I also run a std disc setup with a modified master cyl and that's OK. as well.
As for chains and sprockets since the mid 80's I was amazed how well my o-ring chains lasted on dirt bikes compared to the reynold Norton chains and I just realised on my Africa twin how well the sprockets have lasted. If the sprockets survive on the AT and the Tiger then surely the Norton sprockets must have a fair life span. I have few 520 chains here that I bought for spares and never used so now the plan is to fit 520 o-ring on the 530 chain bikes. Hence the need to machine.
 
I don't know but I have had long life out of my drum/sprockets only on my second one in 46 years and was a everyday ride till 8 years ago, the replacement sprocket was a cast iron one made in India me thinks, the circlip housing broke so ordered a new drum/sprocket from RGM but while waiting was able to machine the circlip housing deeper and put a larger circlip in, so now still on the bike and the new drum/sprocket still under the bench, so can't understand why you not getting long life out of your chains and sprockets, have only replaced my front sprocket once as well, my Norton has well over 160k miles on it since new. The new sprocket from RGM is all steel, but the old sprocket is still hanging in there, but then each bike is different, not sure how you will machine the sprocket down to size without affecting it if you have a decent lathe its easy to mount a Norton drum/sprocket to do some machining on it, I think I had to reverse the jaws to cut the circlip groove deeper but that was over 10 years go when I was working in maintenance workshop and had a larger lathe.
 
ashman said:
I don't know but I have had long life out of my drum/sprockets only on my second one in 46 years and was a everyday ride till 8 years ago, the replacement sprocket was a cast iron one made in India me thinks, the circlip housing broke so ordered a new drum/sprocket from RGM but while waiting was able to machine the circlip housing deeper and put a larger circlip in, so now still on the bike and the new drum/sprocket still under the bench, so can't understand why you not getting long life out of your chains and sprockets,
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Point is that I also think the sprockets should last a fair time, while the Reynold chains did not. Modern 530 non o-ring chains are a tad wide at 21 to23mm with the exception I believe of the Regina classic and Iwis, both hard to locate in N. America, so why not go for the 520.
Have a couple of QC drums here with the bearing loose in the drum. I've inserted a sleeve with a circlip groove, now serviceable, but now trying to make them a 520 drum. When that's sorted I then have a set of sprockets on the Z1 that are 630 that I want to make 530 or 525.
 
andyd said:
Point is that I also think the sprockets should last a fair time, while the Reynold chains did not. Modern 530 non o-ring chains are a tad wide at 21 to23mm with the exception I believe of the Regina classic and Iwis, both hard to locate in N. America, so why not go for the 520.
Have a couple of QC drums here with the bearing loose in the drum. I've inserted a sleeve with a circlip groove, now serviceable, but now trying to make them a 520 drum. When that's sorted I then have a set of sprockets on the Z1 that are 630 that I want to make 530 or 525.
Click to expand...
 
When I bought a new chain off Andy the Chainman he was going away but sent me a chain to Australia before he left, only took 9 days to get here and he sent it before paying for it I had to remind him 2 weeks late to send me the invoice, great bloke to deal with but his son Jason has taken over and also told he is good to deal with as well, Reynold chains are crap and have been for a very long time, my original chain broke while doing a burn out in my miss spent youth, lost about 5 links and shot the chain a 100 yards down the road lol.
 
Have the chrome on the disk stripped in a chrome shop. It is usually quite cheap and it should solve most of your problems, unless the disk is warped.
 
andyd said:
Trying to turn down rear drum sprockets to fit a 520 and front discs to clean them up.
Anyone have any inputs on tool bits and feed rates? Tried hss and carbide bits and asstd speeds - having issues with chatter and poor cutting. Front disc is also an issue due to chrome finish and chatter. I could try milling but it may not be easier or quicker. I have a brake lathe that has not ben used for many years, but not yet thought of using it as I'm thinking that will not improve matters.
Cheers,
Andy
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Sounds like you might, I said you might have a worn lathe.
If any of the Acane threads are worn, or the cross slide nut worn, that can give you chatter no matter how many times you change the lathe speed or the feeds.
I would remove the chrome on the disc completely.
 
I finished cutting the chrome off mine in a rather cheap Chinese tool room lathe, TiN coated carbide. No trouble at all. I would offer your setup is not solid?
 
andyd said:
Not quite so simple. I have a box of discs that I hate to scrap and several drums. I have a Norton with a Brembo master cylinder, std disc and a Lockheed alloy caliper and it's superb, but I also run a std disc setup with a modified master cyl and that's OK. as well.
As for chains and sprockets since the mid 80's I was amazed how well my o-ring chains lasted on dirt bikes compared to the reynold Norton chains and I just realised on my Africa twin how well the sprockets have lasted. If the sprockets survive on the AT and the Tiger then surely the Norton sprockets must have a fair life span. I have few 520 chains here that I bought for spares and never used so now the plan is to fit 520 o-ring on the 530 chain bikes. Hence the need to machine.
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Are you certain that the sprocket needs to be cut down?
Modern x ring 530 is quite a bit narrower than ten year old o ring 530.
I slid an xring 530 on the MK3.
Also on the 650ss and the Vincent.
In order to go to sealed chain, all those bikes would have gotten a 520 " conversion a few years ago.
The sealed chain is the way to go.
You won't be able to make 630 sprockets into 530 or 525.

Glen
 
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Blanchard grinding the rotor +1! You'll chase your tail and waste your day trying to get it flat and true. If you've got a bunch, take 'em all down and get 'em done. Cheaper by the dozen.

For a 520 gearbox sprocket, since the tool post grinder just wouldn't set up right on my lathe (don't remember why), I made a little fixture for my cordless hand drill and held the sprocket against a wide belt sander. Took about 30 minutes of sanding and careful measuring. Came out surprisingly flat for the hack job it was. Same could be done with a drum/rear sprocket just on a bigger scale.
 
I had a company "perform" on my front disc and what a complete disaster the experience was. in the end the disc resembled the thickness of a clutch plate!!
Buy new would be recommendation and you can even get O/E discs drilled from RGM
 
A standard tool room lathe won't be rigid enough for this task. If you have access to a vertical mill it's possible to surface the discs with a face mill (though I personally wouldn't trust it unless I was absolutely certain that the machine was within 0-.0005tir). The rear drum, however, should be easy enough to machine with this setup and a decent rotary table

 
andyd said:
Trying to turn down rear drum sprockets to fit a 520 and front discs to clean them up.
Anyone have any inputs on tool bits and feed rates? Tried hss and carbide bits and asstd speeds - having issues with chatter and poor cutting. Front disc is also an issue due to chrome finish and chatter. I could try milling but it may not be easier or quicker. I have a brake lathe that has not ben used for many years, but not yet thought of using it as I'm thinking that will not improve matters.
Cheers,
Andy
Click to expand...
I routinely install the 520 drum/sprocket from RGM, front sprocket from AN, and DID x-ring 520 chain from Amazon (I have no capability to turn a drum). This guy does a great job inexpensively - not sure if he ships to Canada: https://truedisk.net/ He has done many discs for me.
 
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