For those who have ordered the modified steering head stems; just a note to say that the numbers for the new batch are now up to ten so that the unit price should be reasonable and delivery in January is forecast.
Comet suspension
- Thread starter redbloke1956
- Start date
Hello All. Thank you for your patience; the new batch of modified steering heads is now finished and the stems pressed into the lower blocks. I have just been out and collected a bunch of cardboard boxes for packing and went to the Post Office for prices. Clearly they do not want the business as they want £60 to send one steering head to Australia. Fortunately there are competitors and the best price for Oz is£11 and for the USA £20. I still have to fit the shims and do the paperwork but it means that delivery is on the horizon. Below is a list of names of those who are due to get one. If your name is not on the list then please contact me as you have slipped out of the chaotic Walker filing system. Total cost, including postage is going to be about £300 to Oz and £310 to the USA.
Paul Morse, Greg Brillus, Peter Le Gros, Jan Freymuth, Paul (Highbury), Norman Lord, Chris Launders, Chris Walker, George Charleton, Dick Wheeldon, Paul Norman, Garth Robinson. For those who are based near to me in the UK or who are likely to attend either the next GCM in Coventry or Dick Sherwin's barbecue then I can hand deliver at no cost. I will notify all those above by personal email once everything is completely assembled.
Paul Morse, Greg Brillus, Peter Le Gros, Jan Freymuth, Paul (Highbury), Norman Lord, Chris Launders, Chris Walker, George Charleton, Dick Wheeldon, Paul Norman, Garth Robinson. For those who are based near to me in the UK or who are likely to attend either the next GCM in Coventry or Dick Sherwin's barbecue then I can hand deliver at no cost. I will notify all those above by personal email once everything is completely assembled.
Would Highbury please contact me with a PM as I cannot find your contact details? Cheers
Following information appeared in 2014 in an Australian section newsletter:
The fork blades, part FF40 are made from L40 alloy material which is an old British specification superseded by HE15 which is similar to AS1866-1977 grade 2014.
For straightening or welding first anneal at 360 to 400 degrees centigrade. Solution heat treat at 505 to 515 degrees centigrade for 2 hours. Quench in boiling water then straighten within 30 minutes.
Precipitation harden at 155 to 185 degrees centigrade for 5 hours and furnace cool. This will restore the original hardness of 72 Rockwell B.”
In case anyone is interested in what the above steps are designed to do, first, "solution heat treating" doesn't involve putting the Girdraulic in a bubbling cauldron of some solution. It refers to holding the Al (aluminium) at a high enough temperature to allow all of the alloying element(s) responsible for hardening it -- primarily Cu (copper) in this case -- to go into solid solution in the Al. If the Girduraulics are made of L40 the Cu content is <4.0%, and if they are RR56 it's 2.1%. This is the same as putting so much salt in a cup of room temperature water that some is still left as a solid at the bottom of the cup after as much salt as possible has dissolved. This is a "saturated solution" at that temperature. Heating the Al (or salt water) to a higher temperature and holding it there long enough allows additional Cu (or salt) to go into solution.
Since Cu diffuses fairly slowly in the Al, quenching it doesn't give the excess Cu time to precipitate, resulting in a "supersaturated solution" of the Cu once the Al is back at room temperature. However, since the solution is supersaturated, even at room temperature the Cu atoms would (very) slowly diffuse through the Al, bump into other Cu atoms, and precipitate as microscopic Cu inclusions. These Cu inclusions pin the movement of dislocations in the Al. A soft metal is one in which dislocations move easily, and a hard metal is one in which they move with difficulty, so L40 and RR56 are "precipitate hardened" alloys.
Martyn,
This was I love about this forum, you can learn so much here.
Now I've got a question about the above process you've outlined. When I anneal a metal that has been hardened such as steel I would heat it to the prescribed temp and allow to cool from there at ambient room temp. In the case of a copper head gasket I would heat till cherry red then quench in water, aluminum sheet that has been work hardened I would rub soap on one side and heat from the other side till the soap turns brown, then allow to cool. In the process above would I heat to between 360 and 400 degrees C then allow to cool at ambient room temp then reheat to between 505 and 515 degrees C fro 2 hours and proceed from there as outlined or?
Thanks
Steven
This was I love about this forum, you can learn so much here.
Now I've got a question about the above process you've outlined. When I anneal a metal that has been hardened such as steel I would heat it to the prescribed temp and allow to cool from there at ambient room temp. In the case of a copper head gasket I would heat till cherry red then quench in water, aluminum sheet that has been work hardened I would rub soap on one side and heat from the other side till the soap turns brown, then allow to cool. In the process above would I heat to between 360 and 400 degrees C then allow to cool at ambient room temp then reheat to between 505 and 515 degrees C fro 2 hours and proceed from there as outlined or?
Thanks
Steven
Sorry Mate, can not help you - I was quoting from a section newsletter . But my experience is that what you describe works. To anneal a ferous metal heat it then let it slowley cool, for non ferous, its the reverse, heat it then quickly cool.
Any metallurgists on the forum??
Aluminium in itself needs more than one set of rules. First consider the major alloy in the designation.
1_____ Is almost 99% pure
2_____ Copper
3_____ Manganese
4 _____ Silicon
5 _____ Magnesium
6 _____ Magnesium and Silicon
7 _____ Zinc
Each of these has it`s own set of rules.
For the 1 , 5 , series these are classed as work hardening, but non heat treatable. To avoid excessive grain growth, the material must be brought to temp quickly 360 C held there for 30 minutes and then air cooled.
Heat treatable alloys, 2____ $
First a little more detail of aluminium, there are 7 different grades, these being due to the major alloying element.
The numbers are allocated the first number in the set of four tells us what that element is. 1 --- is 99% pure aluminium. 2 --- is copper 3--- Manganese 4 --- Silicon 5 --- Magnesium 6 --- Magnesium and Silicon 7 --- Zinc
The 1 and 5 series are non heat treatable, but work harden. These are annealed by heating to 360 C held at that temperature for 20 minutes and allowed to air cool. Attain that temperature quickly to avoid any grain growth, which will show a goose pimpling after work.
3 series are also non heat treatable, that series is one I`ve used in the past, but do not see around anymore.
The heat treatable, that have not been heat treated, except for the 7 series, alloys are a little more complex, heating to 360 +10 C for 30 minutes and then cooling in the oven down to 250C, then into the air. Any rework should be carried out in 4 - 5 days.
For those parts that have been heat treated, they should be taken to 400-425C for one hour, cooling should be at 15C per hour down to 300C then into the air for final cool.
The 7--- series Heat to 420C then cool in air, then back into the oven at 225C for 2 - 4 hours to become soft enough to work. If only a small amount of rework is required 2 hours at 300C will suffice.
1_____ Is almost 99% pure
2_____ Copper
3_____ Manganese
4 _____ Silicon
5 _____ Magnesium
6 _____ Magnesium and Silicon
7 _____ Zinc
Each of these has it`s own set of rules.
For the 1 , 5 , series these are classed as work hardening, but non heat treatable. To avoid excessive grain growth, the material must be brought to temp quickly 360 C held there for 30 minutes and then air cooled.
Heat treatable alloys, 2____ $
First a little more detail of aluminium, there are 7 different grades, these being due to the major alloying element.
The numbers are allocated the first number in the set of four tells us what that element is. 1 --- is 99% pure aluminium. 2 --- is copper 3--- Manganese 4 --- Silicon 5 --- Magnesium 6 --- Magnesium and Silicon 7 --- Zinc
The 1 and 5 series are non heat treatable, but work harden. These are annealed by heating to 360 C held at that temperature for 20 minutes and allowed to air cool. Attain that temperature quickly to avoid any grain growth, which will show a goose pimpling after work.
3 series are also non heat treatable, that series is one I`ve used in the past, but do not see around anymore.
The heat treatable, that have not been heat treated, except for the 7 series, alloys are a little more complex, heating to 360 +10 C for 30 minutes and then cooling in the oven down to 250C, then into the air. Any rework should be carried out in 4 - 5 days.
For those parts that have been heat treated, they should be taken to 400-425C for one hour, cooling should be at 15C per hour down to 300C then into the air for final cool.
The 7--- series Heat to 420C then cool in air, then back into the oven at 225C for 2 - 4 hours to become soft enough to work. If only a small amount of rework is required 2 hours at 300C will suffice.
At the beginning of this thread it was found that the then owner of that bike had bent fork blades. They were bent enough that the lower front guard stay would hit the magneto cowl with the front jacked off the ground. He went through the exercise of checking with a straight edge through the centerline of the spindles and lower axle hole, and the blades were bent just below the upper spindle boss, pretty normal to bend at this week point. I think he re straightened the blades in a press cold which worked out ok. If I found that a blade was that badly damaged, rather than go to all the trouble of annealing and so on, I would either find a good original replacement or buy a new one from the Voc spares. Not too many people have the facilities or skills to carry out such a detailed procedure.
Greg,
I agree if mine were severely damaged I would be inclined to replace as I'm not sure I would have the confidence to attempt straightening. But I really did find MartynG and Clevtrev's post interesting and informative. Truthfully I would replace a damaged one and experiment on it, but I would be of two minds to use it.
Steven
I agree if mine were severely damaged I would be inclined to replace as I'm not sure I would have the confidence to attempt straightening. But I really did find MartynG and Clevtrev's post interesting and informative. Truthfully I would replace a damaged one and experiment on it, but I would be of two minds to use it.
Steven
Wonder what 'redbloke1966' , the instigator of this thread did in the end regarding his bent blades?
I was just a callow youth at the time and put mine on v blocks in the works hydraulic press and tweaked them straight.
Did polish them a bit and squirt crack detection fluid on them, but it was just my ride to work Comet.
I was just a callow youth at the time and put mine on v blocks in the works hydraulic press and tweaked them straight.
Did polish them a bit and squirt crack detection fluid on them, but it was just my ride to work Comet.