ET: Engine (Twin) oil holes in Crank pin?
- Thread starter Vincent Brake
- Start date
You don´t talk about hours in projects like I do. The reconstruction started in 1988 or so and I did not note hours certainly. Since there were more projects in between that set times back for many years.
And as to calculating weights of components with a button press on the computer: In 1988 we had no computer in the company, never seen the like at that time. Company means boss and myself, and a Deckel FP 42 NC for programming on the machine , no CAD for decades and myself a complete idiot on CAD still - will never change I believe. All design of my conrods was a matter of paper and pen, some schoolboy trigonometry and pocket calculator for getting coordinates to feed into the CNC milling machine.
The job was started with milling a very oversize rough conrod - well, four of them - out of fat rounds of high tensile case hardening steel and have them carbonized but NOT hardened first. Then I did all final machining of shapes and polishing before having the conrods heat treated. This strategy produces a hard bigend bore and tensile strength for all other faces as all carbon loaded oversize material was machined off . So no need to protect most of any component just for carbonizing small areas that are going to have bearing hardness.
After heat treatment I did final polishing and having big end bearing sizes ground and lapped on the lathe. There are not a lot of places in engines where utmost precision is required but I am very attentive to bigend finish and clearances, so all diameters are diamond-lapped.
Vic
Lapping a Horex conrod for crowded needle bearing with cast iron plus diamond paste:
Lapped HRD conrods:
And as to calculating weights of components with a button press on the computer: In 1988 we had no computer in the company, never seen the like at that time. Company means boss and myself, and a Deckel FP 42 NC for programming on the machine , no CAD for decades and myself a complete idiot on CAD still - will never change I believe. All design of my conrods was a matter of paper and pen, some schoolboy trigonometry and pocket calculator for getting coordinates to feed into the CNC milling machine.
The job was started with milling a very oversize rough conrod - well, four of them - out of fat rounds of high tensile case hardening steel and have them carbonized but NOT hardened first. Then I did all final machining of shapes and polishing before having the conrods heat treated. This strategy produces a hard bigend bore and tensile strength for all other faces as all carbon loaded oversize material was machined off . So no need to protect most of any component just for carbonizing small areas that are going to have bearing hardness.
After heat treatment I did final polishing and having big end bearing sizes ground and lapped on the lathe. There are not a lot of places in engines where utmost precision is required but I am very attentive to bigend finish and clearances, so all diameters are diamond-lapped.
Vic
Lapping a Horex conrod for crowded needle bearing with cast iron plus diamond paste:
Lapped HRD conrods:
my bad, thought they were made within the last decade with CAD being used everywhere. hence: press of a button (age gap is becoming more apparent I believe).
have you run any of these in an engine yet?
have you run any of these in an engine yet?
Victor, you run narrower bigend as stndrd, (24,5mm, No not 25,4) so two rings to centralize the "INA" bearing. in my case.
I will run this crank with my X rotary oil pump, + a mechanical seal on the outside of the timing mainshaft, so oil and presure plenty,
maybe do the diameters of 1,2mm down to 1 mm (can always make bigger). To get rid of oilways where no oil runs, I will change for normal 12.9 inbus bolts all the way down to the crossing hole. No mains and flywheels in one part, as hardend flywheels 1000N/mm2 will hold on to 30 mm bore hardend main axles, and readily available (Neal Videan).
Today I did photos of original NOS R 69 S 36 mm o.d. crankpins, these are for one conrod each, with the boxer crank. Anyway, I did same with the extra long 40 mm o.d. crankpins for the HRDs. The BMW oil feed end you see gets plugged with a hardened plug and is 20 mm but I only wanted 16 mm for the Vincent modded pin. So the two small holes resp. 4 holes in the Vincent special will be set at 90 degrees after passing TDC as written above. My thinking is the oil level in the 20mm resp. 16mm bore will be exactly level to the 4 holes at crank speed even when the oil feed into that 16 mm bore is just from one side. So I expect to have oil suppy into the bearings quite evenly - or not so ??
Vic
Vic
Vic can you tell me how you align the heavy press fit pin into the wheel and keep it all square........also the same when aligning the other wheel/mainshaft......what is the best method here......I ask because I have new flywheels, mains, and heavy press fit pin with no nuts and just wondering how to best go about it.......Cheers........Greg.
not to answer on Vic's behalf, but is there any speedway racing going on in your vicinity, with the modern JAWA engine? have a look at how they do it.
the nice thing about JAWA (from Czech Rep) is they (also) use hardened flywheels and pins, same crank construction as the Vin and Enfield (with all parts press fit but without retaining nuts). perhaps YouTube can show some vids?
the nice thing about JAWA (from Czech Rep) is they (also) use hardened flywheels and pins, same crank construction as the Vin and Enfield (with all parts press fit but without retaining nuts). perhaps YouTube can show some vids?
Vincents do not have press fit crankpins for standard, but nice to have a shoulder on the crankpin that gets bolted up by fat nuts. Even so, not the best idea but sort of tradition and home maintenance suitable - within limits.
Hardened flywheels - not really, but very high tensile certainly and heat treated before finishing all sizes.
As to aligned cranks and press fits, yes Greg, good question. My cranks turned out quite tough after heat treatment, well as intended by my steel choice. But I was a bit worried about trueing the lot after all pressed up. So I got two ground steel plates plus guide pins long enough , ca. 20 mm dia., from the toolroom suppliers no problem . So basically you place the two plates together on the mill with parallels below and drill and ream just three holes in one setup. Two reamed bores on one side with 20mm reamer for nice push fit - plus another bore with nice push fit for mainshaft diameters , like 1 " or in my case 30 mm . That way the lot will end up with mainshafts within say 0.06mm offset like I got on both cranks. The crankpin will find into the matching bores anyway so no more extras to have in the two plates.
In the end I was unable to hit the pressed up cranks for close to zero runout checked on mainshat ends and had to place the lot under the hydraulic press with rounds stuck in balancing holes somehow for twisting them to have like zero runout. Remember 40 mm crankpin and very high tensile webs and press fit at ca. 15 tons or more. Somebody younger may have hit the lot harder than myself possibly for common trueing.
See photos for getting the idea below.
For a friend we modded the Vincent version for the SR 500/XT cranks and bored the mainshaft position to 35 mm , one side. So still you could have an adapter return the jig to Vincent sizes - or other brands. Good enough anyway and quite useful , not just checks by eye and square in the press.
Vic
crank check
timing side
timing side oil holes 90 degrees past TDC:
Hardened flywheels - not really, but very high tensile certainly and heat treated before finishing all sizes.
As to aligned cranks and press fits, yes Greg, good question. My cranks turned out quite tough after heat treatment, well as intended by my steel choice. But I was a bit worried about trueing the lot after all pressed up. So I got two ground steel plates plus guide pins long enough , ca. 20 mm dia., from the toolroom suppliers no problem . So basically you place the two plates together on the mill with parallels below and drill and ream just three holes in one setup. Two reamed bores on one side with 20mm reamer for nice push fit - plus another bore with nice push fit for mainshaft diameters , like 1 " or in my case 30 mm . That way the lot will end up with mainshafts within say 0.06mm offset like I got on both cranks. The crankpin will find into the matching bores anyway so no more extras to have in the two plates.
In the end I was unable to hit the pressed up cranks for close to zero runout checked on mainshat ends and had to place the lot under the hydraulic press with rounds stuck in balancing holes somehow for twisting them to have like zero runout. Remember 40 mm crankpin and very high tensile webs and press fit at ca. 15 tons or more. Somebody younger may have hit the lot harder than myself possibly for common trueing.
See photos for getting the idea below.
For a friend we modded the Vincent version for the SR 500/XT cranks and bored the mainshaft position to 35 mm , one side. So still you could have an adapter return the jig to Vincent sizes - or other brands. Good enough anyway and quite useful , not just checks by eye and square in the press.
Vic
crank check
timing side
timing side oil holes 90 degrees past TDC:
I don't know if Roy the racer will have the time to do a full reply to all this but with his design (lamb chop) you do not need all the holes and the sides of the flywheels are parallel not sculpted, recessed or whatever. One or two ground holes were made in each flywheel in the opposite side to the crankpin hole. These holes were ground to about 0.0001" as were two rods which were inserted to ensure that the flywheels went together parallel. The main shafts were slightly oversized and then ground back to size to ensure that everything was in line to about 0.0001". My engineering knowledge is insufficient to give you a technical description of the equipment used so it would be better if Roy explains it himself.